Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘Z’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘Z’
ZAF corrections – It is a quantitative X-ray programme which corrects for atomic number (Z), absorption (A), and fluorescence (F) effects in a matrix.
z-axis – It is the third dimension in a three-dimensional Cartesian coordinate system. It is perpendicular to both the x-axis and y-axis and is used to represent depth or height. In simpler terms, in a 3D space, the x-axis is left-right, the y-axis is up-down, and the z-axis is forward-backward. In composite laminates, z-axis is the reference axis normal to the plane of the laminate.
Zeeman effect – It is a splitting of a degenerate electron energy level into states of slightly different energies in the presence of an external magnetic field. This effect is useful for background correction in atomic absorption spectrometers.
Zener breakdown – It is a type of electrical breakdown in a reverse-biased p-n junction diode, where a strong electric field causes electrons to tunnel from the valence band to the conduction band, leading to a sudden increase in reverse current. It occurs in heavily doped diodes with a narrow depletion region.
Zener diode – It is the nickname for ‘voltage regulator diodes’ which can rely either on the Zener effect or avalanche breakdown to maintain a roughly constant voltage. The two effects have opposite temperature coefficients of voltage.
Zener drag – It also known as Zener pinning. It is the interaction between particles and grain boundaries responsible for a presence of restraining forces affecting grain boundary mobility. It is a phenomenon where second-phase particles (like precipitates) hinder the movement of grain boundaries in a material, hence slowing or even stopping grain boundary migration. This effect is crucial in controlling micro-structure and properties of materials, particularly during processes like grain growth.
Zener effect – It is also known as Zener breakdown. It is a type of electrical breakdown in a reverse-biased p-n junction diode. It occurs when a strong electric field causes electrons to tunnel from the valence band to the conduction band, leading to a sudden increase in reverse current. This effect is normally utilized in Zener diodes for voltage regulation.
Zener–Hollomon parameter – It is typically denoted as ‘Z’. It is used to relate changes in temperature or strain-rate to the stress-strain behaviour of a material. It has been most extensively applied to the forming of steels at increased temperature, when creep is active. It is given by equation Z = e exp(Q/RT)Z=ε˙exp(Q/RT) where ‘e’ε˙ is the strain rate, ‘Q’ is the activation energy, ‘R’ is the gas constant, and ‘T’ is the temperature. The Zener–Hollomon parameter is also known as the temperature compensated strain rate, since the two are inversely proportional in the definition.
Zener pinning – It is the influence of a dispersion of fine particles on the movement of low-angle and high-angle grain boundaries through a polycrystalline material. Small particles act to prevent the motion of such boundaries by exerting a pinning pressure which counteracts the driving force pushing the boundaries. Zener pinning is very important in materials processing as it has a strong influence on recovery, recrystallization and grain growth.
Zener voltage – It is defined as the voltage at which a Zener diode undergoes reverse breakdown, allowing it to regulate voltage within a specified range, typically controlled by the diode’s dimensions and impurities. This breakdown voltage can be adjusted from around 2.4 volts up to hundreds of volts.
Zener-Wert-Avrami (ZWA) function – It is also known as the Avrami equation. It is a mathematical model used to describe the kinetics of phase transformations in materials, particularly in the context of solid-state transformations like precipitation, crystallization, and recrystallization. It is frequently applied to understand and predict how residual stresses relax during heat treatment processes. In essence, the Zener-Wert-Avrami equation describes the fraction of a material transformed as a function of time and temperature. Zener-Wert-Avrami function is a powerful tool for providing a framework for predicting how these processes evolve over time and temperature.
Zeolite – It is a kind of crystalline hydrated alumino-silicate material with a regular pore structure. Its unique physical and chemical properties give it good adsorption, catalytic, shape selectivity, and ion exchange characteristics. Compared with other inorganic materials, zeolites are widely used as catalysts, ion exchangers, and adsorbents because of their adjustable chemical properties, controllable pore structures, and good hydrothermal stability. Zeolites are a class of microporous, crystalline aluminosilicate minerals characterized by their unique honeycomb-like structure, which allows them to act as molecular sieves and shape-selective catalysts. They are composed of silicon, aluminum, and oxygen, with some silicon atoms replaced by aluminum, creating a negatively charged framework that can accommodate cations. This structure enables them to selectively adsorb molecules based on size and shape. Zeolites are of two types namely (i) natural zeolites, and (ii) synthetic zeolites. Natural zeolites are non-porous, e.g., Natrolite (Na2O.Al2O3.4SiO2.2H2O). Synthetic zeolites are porous and prepared by heating together china-clay, feldspar (AlNaO8Si3) and soda ash. Synthetic zeolites possess higher exchange capacity per unit weight than natural zeolites.
Zeolite membrane – It is a thin layer of crystalline alumino-silicate material with a highly ordered porous structure, used for separating gas and liquid mixtures based on molecular size and adsorption properties. These membranes are known for their high chemical and thermal stability, making them suitable for several separation processes like gas separation, pervaporation, and water desalination.
Zeolite process – It is also called Permutit process. It is a process of removing the permanent as well as temporary hardness of the water. It involves the precipitation of calcium and magnesium ions present in water. The exchange of and ions occurs with the help of zeolite and hence, it is known as Zeolite softening process. For softening of water by zeolite process, hard water is percolated at a specified rate through a bed of zeolite, kept in a cylindrical vessel. The hardness causing ions (Ca2+, Mg2+) are retained by the zeolite as CaZe and MgZe, while the outgoing water contains sodium salts. Reactions taking place during the softening process are (i) Na2Ze + Ca(HCO3)2 = CaZe + 2NaHCO3, (ii) Na2Ze + Mg(HCO3)2 = MgZe + 2NaHCO3, (iii) Na2Ze + CaCl2 = CaZe + 2NaCl, and (iv) Na2Ze + MgCl2 = MgZe + 2NaCl. After some time, the zeolite is completely converted into calcium and magnesium zeolites and it ceases to soften water, i.e., it gets exhausted. At this stage, the supply of water is stopped and the exhausted zeolite is reclaimed by treating the bed with brine solution (10 % NaCl solution). The reaction which takes place during regeneration is given by the equation CaZe (or MgZe) + 2NaCl = Na2Ze + CaCl2 (or MgCl2). The washings (waste liquor) containing CaCl2 and MgCl2 are sent to the drain and the regenerated zeolite bed hence obtained is used again for softening purpose.
Zero-based budgeting (ZBB) – It is a concept which came in 1970 to help organizations manage their costs better. Zero-based budgeting, as opposed to traditional budgeting, does not automatically include any item in the next year’s budget. Although the concept became vague and outdated as organizations went back to conventional budgeting techniques, it is gaining back traction as some experts find that annual budget created through Zero-based budgeting is aligned to overall strategy and helps improve operational efficiency by challenging assumptions under conventional budgeting.
Zero bleed – It is a laminate fabrication procedure which does not allow loss of resin during cure. It also describes prepreg made with the quantity of resin desired in the final part, such that no resin has to be removed during cure.
Zero-carbon energy carrier – It is defined as a substance, such as hydrogen or ammonia, which facilitates the transfer of energy without emitting carbon di-oxide, thereby supporting economy-wide decarbonization efforts and addressing technical and economic challenges in energy transport and storage.
Zero crossing rate (ZCR) – It is defined as the measure of how many times a waveform crosses the zero axis, determined by counting instances where the signal transitions from negative to positive and vice versa, while accounting for a threshold to avoid miscounting because of the noise.
Zero current switching (ZCS) – It is defined as a technique in which a switch is turned off when the current through it is zero. It is achieved through resonance between an inductor and a capacitor. This method aims to shape the switch current waveform during conduction to ensure a zero-current condition at the moment of commutation.
Zero defects (ZD) – It is a management-led programme to eliminate defects in industrial production. Although applicable to any type of organization, it has been mainly adopted within supply chains wherever large volumes of components are being purchased (common items such as nuts and bolts are good examples).
Zero-dimension model – It is defined as a simplified model which makes mass and heat balances over an entire system to predict gas composition, without accounting for spatial variations within the system.
Zero ductility temperature (ZDT) – It is the temperature at which a material loses all measurable ductility, meaning it will fracture without any plastic deformation. Essentially, it is the temperature below which a material transitions from showing some ability to deform before breaking (ductile behaviour) to fracturing immediately upon reaching its yield strength (brittle behaviour).
Zero emission – It means the absence of harmful gas or pollutant release into the atmosphere. Specifically, it refers to vehicles or technologies which produce no emissions during operation, such as electric cars and hydrogen fuel cell vehicles. This concept is crucial for reducing pollution and mitigating climate change by eliminating emissions from fossil fuel combustion.
Zero-emission batteries – These batteries refer to those batteries which, during their operation, produce no harmful emissions or pollutants. This means they do not release any greenhouse gases or other toxic substances into the atmosphere. They are a key component in zero-emission vehicles (ZEVs), which rely on these batteries to power electric motors and avoid the use of fossil fuels.
Zero emission building – It is defined as structures which achieve high energy efficiency and produce sufficient emissions-free renewable energy to meet their energy demands over a specific period. It plays a crucial role in reducing dependency on fossil fuels and minimizing greenhouse gas emissions in the building sector.
Zero emission technologies – These refer to energy solutions which produce no carbon di-oxide emissions during operation, hence reducing substantially greenhouse gas emissions. These technologies can include renewable energy sources such as photovoltaics, wind, and fuel cells, as well as advanced nuclear power plants.
Zero energy building – It is defined as the building which achieve zero carbon emissions annually by reducing the energy demand and utilizing renewable energy sources to meet the reduced needs. A zero-energy building can be assessed in different ways, including net zero site energy use, net zero source energy use, and net zero energy emissions.
Zero error – In the context of measuring instruments, it refers to the reading displayed by the instrument when it is ideally to be at zero. It is a type of systematic error which occurs when the instrument’s zero mark does not align with the actual zero point, leading to consistent inaccuracies in measurements.
Zero forcing precoding – It is defined as a linear precoding technique which effectively cancels multiuser interference in high signal-to-noise ratio (SNR) conditions, enabling full spatial multiplexing and multiuser diversity gains, while being limited to serving a number of single antenna users equal to the number of transmit antennas.
Zero frequency – It refers to the substitution of data points as 0 (zero) when there is a lack of observation for a class, leading to inaccurate predictions.
Zero-growth rate – It is also known as no-growth rate. It signifies a situation where there is no increase or decrease in a value or quantity over time. In financial contexts, it means the value of assets or cash flows remains constant.
Zero liquid discharge (ZLD) – It is defined as a treatment process which eliminates liquid effluent discharge into surface waters, hence preventing environmental pollution and promoting waste-water recycling and reuse for water conservation.
Zero-order Laue zone (ZOLZ) – It is a specific plane in reciprocal space which contains the origin (000) and is perpendicular to the incident electron beam in electron diffraction. It essentially represents the intersection of the Ewald sphere with the reciprocal lattice plane passing through the origin. Reflections within the zero-order Laue zone are characterized by their proximity to the transmitted beam and their symmetry, which reflects the crystal structure projected along the incident beam direction.
Zero-pressure accumulating conveyor – It is a conveyor system meticulously engineered to eradicate any pressure or force exerted between closely positioned products.
Zero-sequence circuit – It is defined as an equivalent circuit model where the three zero-sequence voltages are in phase with each other, resulting in a phase shift of zero between input and output voltages. It is influenced by the winding connections of series and shunt transformers and their core construction.
Zero sequence components – These components refer to the equal magnitude and phase components that arise from asymmetrical earth fault conditions and unbalanced loads in a three-phase system. They can only flow where a return path to the neutral exists and are distinct from positive and negative sequence impedances.
Zero sequence voltage – It is defined as one-third of the sum of the phase voltages in a three-phase system It is represented mathematically as Va0 = 1/3 (Va + Vb + Vc). This voltage measurement can be obtained using specific configurations of voltage transformers or balanced impedances connected to the three lines.
Zero strength temperature (ZST) – It refers to the temperature at which a material, typically steel, loses all measurable strength and can no longer support any load. This occurs because of the melting of grain boundaries during heating or solidification, preventing the material from transferring forces perpendicularly to the solidification direction. It is a critical parameter in processes like casting and welding, where understanding zero strength temperature helps to prevent defects.
Zero-time delay – It is defined as the immediate response of a system or instrument when exciting charge carriers, such as in a pump /mid-infrared probe experiment, where the generation of charge carriers occurs instantaneously upon photon absorption.
Zeroth approximation – It is defined as an approach where the energy of an individual atom in a system is determined by the average degree of order prevailing in the entire system, rather than by the fluctuating configurations of neighboring atoms. This approximation is characterized by its insensitivity to the detailed structure or dimensionality of the lattice.
Zeroth law of thermodynamics – It states that if two thermodynamic systems are each in thermal equilibrium with a third one, then they are in thermal equilibrium with each other, i.e., If body ‘A’ is in thermal equilibrium (no heat transfers between them when in contact) with body ‘C’, and body ‘B’ is in thermal equilibrium with body ‘C’, then ‘A’ is in thermal equilibrium with ‘B’. Hence, thermal equilibrium between systems is a transitive relation. Two systems are said to be in the relation of thermal equilibrium if they are linked by a wall permeable only to heat and they do not change over time. As a convenience of language, systems are sometimes also said to be in a relation of thermal equilibrium if they are not linked so as to be able to transfer heat to each other, but are still not to do so (even) if they are connected by a wall permeable only to heat.
Zero time – It is the time when the given loading or constraint conditions are initially obtained in creep or stress-relaxation tests, respectively.
Zero voltage switching (ZVS) – It is defined as a method which allows a power switch and diode to turn on and off at zero voltage, minimizing voltage and current stresses, hence reducing switching losses in converters.
Zeta layer – It is the third layer of zinc-iron alloy growth from the base steel formed during the galvanizing process. The chemical composition of this layer is around 94 % zinc and 6 % iron. The Zeta layer has a DPN (diamond pyramid number) hardness of 179, compared to the base steel’s DPN hardness of 159.
Zeta potential – It is also called electro-kinetic potential. It is a potential difference in the solution caused by residual, unbalanced charge distribution in the adjoining solution, producing a double layer. The Zeta potential is different from the electrode potential in that it occurs exclusively in the solution phase, i.e., it represents the reversible work necessary to bring unit charge from infinity in the solution up to the interface in question but not through the interface.
Zeta potential measurements – These measurements refer to the characterization of the surface charge of nano-materials, which is used to study the effectiveness of capping agents and assess the stability of nano-particles. The zeta potential value can be either positive or negative, depending on the nature of the capping agent.
Ziegler-Natta poly-propylene – It refers to poly-propylene produced using titanium Ziegler–Natta catalysts, which are typically manufactured as magnesium chloride supported solids and activated with aluminum alkyls. This process is normally utilized in several technologies.
Ziegler-Nichols tuning method – It is a widely used heuristic technique for tuning PID (proportional-integral-derivative) controllers. It provides a systematic approach to determine initial values for the proportional-integral-derivative parameters (proportional gain, integral time, and derivative time) based on the behaviour of the controlled system. The method aims to achieve a stable and responsive control system, frequently by finding the gain which produces sustained oscillations and then using those oscillations to calculate the proportional-integral-derivative parameters.
ZigBee protocol – It is defined as a wireless communication standard designed for short-duration, low-energy consumption applications, primarily in the Internet of Things (IoT), utilizing the Institute of Electrical and Electronics Engineers IEEE 802.15.4 base protocol. It supports several device types including coordinators, routers, and end devices, facilitating efficient network management and communication.
Zig-zag configuration – It refers to a method of connecting three single-phase transformers which provides a path for zero sequence load currents, effectively handling unbalanced loads and ground fault conditions by constructing the windings in a zigzag manner.
Zig-zag grounding banks – These banks are used to provide a fourth wire for phase-to-ground loads on distribution systems. They use a zig-zag transformer configuration to step down voltage in a more efficient way than a wye-delta transformer.
Zig-zag transformer – It is a multi-winding three phase transformer which is sometimes used for grounding.
Zig-zag transformer winding – It is a special-purpose transformer winding with a zigzag or ‘inter-connected star’ connection, such that each output is the vector sum of two (2) phases offset by 120-degree. It is used as a grounding transformer, creating a missing neutral connection from an ungrounded 3-phase system to permit the grounding of that neutral to an earth reference point, to perform harmonic mitigation, as they can suppress triplet (3rd, 9th, 15th, and 21st etc.) harmonic currents, to supply 3-phase power as an auto-transformer (serving as the primary and secondary with no isolated circuits), and to supply non-standard, phase-shifted, 3-phase power. Nine-winding, three-phase transformers typically have three primaries and six identical secondary windings, which can be used in zigzag winding connection.
Zinc (Zn) – It is a chemical element having atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. In some respects, zinc is chemically similar to magnesium (Mg) with both elements showing only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size. Zinc is more reactive than iron (the main component of steel). When exposed to moisture and oxygen, zinc forms a protective layer of zinc oxide, zinc hydroxide, and zinc carbonate, which adheres to the surface and blocks further corrosion. Zinc weathers at a very slow rate, so the coating normally has a long life. Zinc has a greater electro-negativity than iron and hence provides cathodic (or sacrificial) protection to the steel. This results in the zinc corroding in preference to the steel if the coating is chipped or damaged to expose the base metal, besides acting as galvanic protector. Zinc has five stable isotopes. The most common zinc ore is sphalerite (zinc blende) which is a zinc sulphide mineral. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity (electro-winning). In its purer form, zinc is available as slabs, ingots, shot, powder, and dust. Slab zinc is produced in three grades. Impurity limits are very important when zinc is used for alloying purposes. Exceeding impurity limits can result in poor mechanical and corrosion properties. Pure zinc shot is used mainly for additions to electro-galvanizing baths, and zinc powder and dust are used in batteries and in improved corrosion-resistant paints.
Zinc-air batteries – These batteries are defined as electro-chemical cells which utilize zinc powder anodes, catalytic cathodes, and an alkaline electrolyte, where atmospheric oxygen serves as the active cathode. They are known for their high energy storage capacity and flat discharge curves, although they typically have a short life-span of 1 month 3 months because of the air leakage.
Zinc alloy castings – Zinc alloys are used extensively in both gravity and pressure die castings. When used as general casting alloys, zinc alloys can be cast using such processes as high-pressure die casting, low-pressure die casting, sand casting, permanent mould casting (iron, graphite, or plaster moulds), spin casting (silicone rubber moulds), investment (lost-wax) casting, continuous or semi-continuous casting, and centrifugal casting. A newer process involves semi-solid casting, of which several techniques can be used. Corrosion is of no concern for majority of applications. However, for castings under moderate-to-severe corrosive attack, some loss of properties is to be expected. Long-term aging also can cause some small loss of properties; the effects vary from alloy to alloy and depend upon the casting method used. All zinc casting alloys have excellent machining properties, with long tool life, low cutting forces, good surface finish, low tool wear, and small chip formation. Common machining operations performed on these alloys include drilling, tapping, reaming, broaching, routing, turning, milling, die threading, and sawing. Zinc alloy castings can be conveniently joined by soldering or brazing, or by certain welding techniques using zinc-base fillers. Cadmium-base, tin-base, or lead-base solders are not recommended since they can promote intergranular corrosion problems unless the castings are plated with heavy coatings of nickel or copper prior to soldering. Newer zinc-base solders are becoming available. Adhesive bonding or mechanical fasteners are also excellent methods for joining castings. Zinc castings can be riveted, staked, and crimped. Threaded fasteners, including self-tapping screws, are not to be over-tightened but rather tightened to recommended torques. Up to 40 % loss of torque is to be incorporated into the design for parts operating at high temperatures of 50 deg C or higher. Substantial torque loss can be avoided by using special fasteners, including cone (spring or Belleville) or star washers of the correct.
Zinc alloy plating – It is a process where a thin layer of a zinc-based alloy is applied to a metal object, typically through electro-deposition, to improve its corrosion resistance, wear resistance, and appearance. This coating provides a sacrificial layer, protecting the underlying metal from rust and other forms of corrosion. Common zinc alloys used in plating include zinc-nickel and zinc-iron.
Zinc ammonium chloride – It is the typical component of the flux solution used in the cleaning phase of the galvanizing process.
Zinc blende – It is a mineral form of zinc sulphide (ZnS) with a cubic crystal structure. It is also known as sphalerite and is a common sulphide ore of zinc. Zinc blende has a 1:1 ratio of zinc and sulphur atoms, with a tetrahedral arrangement of ions.
Zinc-bromine flow battery – It is defined as a type of flow battery which features a high energy density and can charge and discharge with a large capacity and a long life, utilizing an aqueous solution of zinc bromide as the main reactant. It allows for frequent 100 % deep discharge without affecting performance. Its design promotes safety and recyclability.
Zinc calcines – It is the product of the reaction of zinc sulphidic-concentrates, and optionally, other primary or secondary zinc-bearing materials which is roasted in furnace at high temperature or blow with air.
Zinc carbonate patina – It is the relatively insoluble zinc carbonate layer which forms as the galvanized coating weathers, providing added corrosion protection and abrasion resistance.
Zinc-carbon batteries – These are a type of galvanic cell which utilize zinc as the anode, manganese di-oxide as the cathode, and ammonium chloride or zinc chloride as the electrolyte. It offers an economical power source with acceptable performance for several applications.
Zinc casting alloys – Zinc casting alloys have dendritic / eutectic microstructures. The hypoeutectic alloys solidify with zinc-rich (eta) dendrites, whereas the hypereutectic alloys solidify with aluminum-rich dendrites. It is critically important that all zinc-aluminum casting alloys be carefully handled to prevent excessive pickup of harmful impurity elements such as lead, cadmium, tin, and iron, among others. Cross contamination caused by melting the alloys in furnaces used for casting copper and aluminum alloys or iron is particularly troublesome since these alloys contain elements harmful to zinc alloys. Purity concerns have led producers to require that only 100 % virgin material be used in the production of zinc foundry alloys. A maximum 50 % remelt of foundry returns to the melting furnace is acceptable during the making of castings. Zinc alloys have low melting points, need relatively low heat input, do not need fluxing or protective atmospheres, and are non-polluting. The rapid chilling rate inherent in zinc die castings results in minor property and dimensional changes with time, particularly if the casting is quenched from the die rather than air cooled. Although this is rarely a problem, a stabilizing heat treatment can be applied prior to service if rigid dimensional tolerances are to be met. The higher the heat treatment temperature, the shorter the stabilizing time needed with 100 deg C is a practical limit to prevent blistering of the casting or other problems. A common treatment consists of 3 hours to 6 hours at 100 deg C, followed by air cooling. The time extends to 10 hours to 20 hours for a treatment temperature of 70 deg C. Because of their high fluidity, zinc alloys can be cast in much thinner walls than other die castings alloys, and they can be die-cast to tighter dimensional tolerances. Zinc alloys allow the use of very low draft angles. In some cases, a zero draft angle is possible.
Zinc castings – These castings refer to components fabricated through the die-casting process using zinc alloys, characterized by their ability to be produced rapidly, with intricate detail, tight dimensional tolerances, and excellent surface finish. They are known for their thin-wall casting capability, good machinability, and receptiveness to different finishing techniques, making them widely applicable in industries such as automotive and electronics.
Zinc chloride (ZnCl2) – It is a chemical compound composed of zinc and chlorine. It is a white, crystalline, and hygroscopic solid that readily absorbs moisture from the air. It is highly soluble in water and has several industrial applications, including use as a flux, dehydrating agent, and in textile and paper processing.
Zinc coated sheet and strip – In this the sheet and strip are coated with zinc (i) by dipping in a bath of molten zinc with the mass of the zinc varies in general between 100 grams per square meter to 700 grams per square meter total on both the sides and the coating having a spangle, minimized spangle, or without spangle finish, and (ii) by electrolytic deposition with the mass of the zinc varying in general between 7 grams per square meter and 107 grams per square meter on each side corresponding to a coating thickness of 1 micro-meter to 15 micro-meters on each side. After zinc coating, the surfaces can be passivated by chromating or phosphating.
Zinc-coated steel – It is also known as galvanized steel. It is steel that has been coated with a layer of zinc to protect it from corrosion. This coating acts as a barrier, preventing the steel from rusting when exposed to moisture and oxygen. The zinc also provides sacrificial protection, meaning it corrodes preferentially to the steel if the coating is damaged.
Zinc coating – It is a protective layer of zinc applied to a metal surface, typically steel, to prevent corrosion (rusting). This process, frequently called galvanizing, uses zinc’s ability to act as a sacrificial anode, meaning it corrodes preferentially to the underlying metal, hence protecting it from rust. The use of zinc as a coating to protect steel and iron from corrosion is the largest single application for the metal worldwide. Metallic zinc coatings are applied to steels namely (i) from a molten metal bath (hot dip galvanizing), (ii) by electrochemical means (electro-galvanizing), (iii) from a spray of molten metal (metallizing), and (iv) in the form of zinc powder by chemical / mechanical means (mechanical galvanizing). Zinc coatings are applied to several different types of products, ranging in size from small fasteners to continuous strip to large structural shapes and assemblies.
Zinc-cobalt plating – Zinc-cobalt coatings contain 0.6 % to 2 % cobalt. Zinc-cobalt alloys find extensive use for relatively inexpensive components in applications which need improved abrasion resistance and corrosion protection. Typically, an 8 micrometers film with 1 % cobalt lasts up to 500 hours in a neutral salt spray test before red rust appears if the proper chromate is applied. Some reduction in corrosion resistance is experienced after exposure to high temperature, but not as much as with zinc-iron alloys. A unique attribute of zinc-cobalt is its corrosion resistance to sulphur di-oxide in accelerated corrosion tests. This suggests that these coatings can be suitable for use in sulphur-containing corrosive environments. There are two types of zinc-cobalt plating baths namely acid and alkaline. Alkaline baths are preferred for tubes and other configurations with internal unplated areas. Exposure to acidic electrolyte reduces the corrosion resistance of such parts. Available chromates include clear, yellow, iridescent and black.
Zinc concentrate – It is a processed mineral material containing a high concentration of zinc, typically extracted from zinc ore through beneficiation processes like flotation. It is a crucial intermediate product used in the production of metallic zinc and different zinc-containing products.
Zinc deposits – These deposits refer to the different morphological forms of zinc which are plated from aqueous alkaline electrolytes, which can include heavy spongy, dendritic, filamentous mossy, boulder, and layer-like structures, each influenced by factors such as substrate type, surface treatment, electrolyte composition, and current density. For practical applications, well-adherent boulder or layer-like deposits are preferred, while other forms can hinder performance in battery cycling.
Zinc di-alkyl-di-thio-phosphate (ZDDP) – It is a chemical compound widely used as an anti-wear and antioxidant additive in lubricants, particularly in engine oils. It’s a coordination compound consisting of zinc bound to the anion of a di-alkyl-di-thio-phosphoric acid. Zinc di-alkyl-di-thio-phosphates are known for their ability to form protective tribo-films on metal surfaces under friction, which reduces wear and extends the life of engine components.
Zinc dust – It is a fine powder composed of metallic zinc. It is characterized by its bluish-gray colour and is used as a reducing agent, a pigment in corrosion-resistant coatings, and in several industrial applications. It is produced by condensing zinc vapour and is frequently spherical in shape.
Zinc electrode – It is defined as a component in nickel-zinc battery technology, typically composed of zinc oxide mixed with additives like calcium oxide, which improve conductivity and anti-corrosive properties, while also influencing discharge product solubility and cell energy density.
Zinc flake coatings – These are non-electrolytically applied coatings, which provide good protection against corrosion. These coatings consist of a mixture of zinc and aluminium flakes, which are bonded together by an inorganic matrix. The specifications for zinc flake coatings are defined in International Organization for Standardization standard ISO 10683 and also in European standard EN 13858. ISO 10683 sets out the requirements for zinc flake coatings for threaded fasteners and EN 13858 describes the requirements for zinc flake coatings for fasteners with no thread and for other parts as well. There are three groups of zinc flake coatings namely (i) zinc flake coatings containing Cr (VI) (hexavalent chromium) with surfaces containing Cr (VI) provide higher anti-corrosion protection with a thinner coating, but Cr (VI) is carcinogenic and poses a potential risk to the environment, (ii) solvent-based Cr (VI)-free zinc flake coatings, and (iii) water-based Cr (VI)-free zinc flake coatings.
Zinc flake powder – It is made from spherical zinc powder by dry ball milling with lubricants. Zinc flake powder has stronger covering, floating and shielding properties as well as better metallic lustre than spherical zinc powder.
Zinc-ion battery (ZIB) – It is defined as energy storage device which utilizes zinc as the charge carrier, offering advantages such as low cost, environmental friendliness, safety, and a long life cycle compared to lithium-ion batteries. They feature high volumetric energy density and operate with aqueous electrolytes, avoiding issues like dendrite formation.
Zinc hydroxide – It is the corrosion product formed in response to the presence of moisture on galvanized articles.
Zinc-iron alloy layers – These are inner layers of the galvanized coating formed from interdiffusion reactions between iron in the base steel and molten zinc metal, (e.g., delta, gamma, and zeta layers).
Zinc-iron plating – It is a process where a thin layer of zinc alloyed with a small amount of iron is deposited onto a metal substrate, typically steel. This alloy coating provides improved corrosion resistance compared to plain zinc plating and is frequently used as an alternative to cadmium plating. The iron content in the coating is normally between 0.4 % and 1 % by weight. Zinc-iron plating involves depositing a layer of zinc alloyed with iron onto a metal surface. The iron content in the deposit is a key factor in its properties. Zinc-iron plating produces alloys containing 15 % to 25 % iron (Fe) as-plated. Advantages of this alloy are good weldability and ductility. It is electroplated on steel coil and strip for auto bodies. Strip for the manufacture of automotive components is also plated in baths that produce 1 % Fe in the alloy deposit, a special feature of this alloy is its suitability for deep black chromating. The corrosion resistance of zinc-iron is normally lower than that of the other zinc alloys, especially after exposure to high temperatures such as those encountered by under-the-hood automotive components.
Zinc mine – It is defined as a location where zinc ores, which typically contain 5 % to 15 % zinc, are extracted for processing and production of zinc metal. The majority of zinc mines are operated underground, with some utilizing open pit methods.
Zinc nickel (Zn-Ni) – It is an alloy coating, typically composed of 85 % to 88 % zinc and 12 % to 15 % nickel, used to protect metal surfaces from corrosion. This alloy is applied through electro-plating, where a layer of zinc-nickel is deposited onto a base metal, normally steel, using an electric current. This coating offers superior corrosion resistance compared to zinc alone, particularly in demanding environments.
Zinc-nickel alloy – Zinc-nickel alloys produce the highest corrosion resistance of electroplated zinc alloys. These alloys contain from 5 % to 15 % nickel. Corrosion resistance improves with nickel content up to 1 % to 18 %. Beyond this range the alloy becomes more noble than steel and loses its sacrificial protection property. An alloy containing 10 % to 13 % nickel is electro-plated on steel strip and coil as an alternative to zinc-iron or electro-galvanizing. An advantage of this composition is the formability of the steel after coiling. For components, chromatizing is needed. However, best results are achieved on alloys containing 5 % to 10 % nickel Ni. For alloys in this range of nickel content, corrosion resistance to neutral salt spray reaches 1000 hours or more before red rust. An advantage of zinc-nickel alloys is their retention of 60 % to 80 % of their corrosion resistance after forming and after heat treatment of plated components. This attribute makes these alloys suitable for automotive applications such as fasteners, brake and fuel lines, and other under-the-hood components.
Zinc-nickel alloy coated sheet and strip – In this product sheet or strip is coated electrolytically with a zinc-nickel alloy, with a coating thickness normally between 1 micro-meter to 8.5 micro-meters per side.
Zinc-nickel alloys plating – Zinc-nickel alloys plated from alkaline baths have shown potential as substitutes for cadmium coatings. Available chromates are clear, iridescent, bronze, and black. Alkaline formulations are preferred for their ease of operation and since they provide more uniform alloy composition and better overall corrosion resistance, especially on tubing and on internal configurations of parts.
Zinc ore – It is a naturally occurring rock or mineral deposit containing zinc, a metallic element used in several industrial applications. It is not found as a pure metal in the earth, but rather as compounds like zinc sulphide (sphalerite), zinc carbonate (smithsonite), and zinc silicate. These ores are mined and processed to extract the zinc metal.
Zinc oxide – Combined with oxygen, zinc is available as zinc oxide powder. Zinc oxide is used as a pigment in primers and finish paint, as a reducing agent in chemical processes, and as a common additive in the production of rubber products. Zinc oxide is also the basic corrosion product formed almost instantaneously on freshly galvanized articles after withdrawal from the molten zinc metal.
Zinc oxide nano-particles – These nano-particles are defined as nano-structured zinc oxide materials which show unique properties different from their bulk counterpart, and they are utilized in several applications including chemical sensors, photo-catalysis, and opto-electronics because of their excellent structural, electrical, and optical characteristics.
Zinc patina – It is relatively insoluble zinc carbonate layer which forms as the galvanized coating weathers, providing added corrosion protection and abrasion resistance.
Zinc phosphate coating – It is a type of chemical conversion coating used to treat metal surfaces, mainly steel, to improve corrosion resistance and improve the adhesion of subsequent coatings like paint. They are formed by reacting the metal surface with a phosphate solution, resulting in a crystalline layer of zinc phosphate. This layer acts as a barrier to corrosion and provides a good foundation for other finishes. Zinc phosphate coatings are inorganic, crystalline layers formed on metal surfaces through a chemical reaction.
Zinc plating – It is a process in which a thin layer of zinc is electroplated onto a metal substrate, typically steel or iron. The main purpose of zinc plating is to provide corrosion resistance to the underlying metal, helping prevent rust and degradation when exposed to moisture and air. The zinc layer acts as a sacrificial barrier, corroding first before the base metal does, offering protection over time. The plating process is relatively simple and cost-effective, making it widely used in manufacturing. Zinc Plating also provides a smooth, shiny finish which improves the aesthetic appearance of the product. It is frequently used in industries such as automotive, construction, and electronics.
Zinc powder – It refers to a finely divided form of metallic zinc, typically with particles ranging from sub-micron to a few hundred micro-meters in size. This powder is used as a raw material to create several components and products through powder processing techniques. The high surface area of zinc powder makes it reactive and suitable for several applications, including chemical reactions and as a component in batteries.
Zinc refining – It is defined as a process mainly involving electrolysis to recover metallic zinc from ores, with techniques such as electro-winning representing over 80 % of global zinc production. It also includes the recovery of by-products such as indium and other minor metals through electrolytic methods.
Zinc-rich paint – It is also called cold galvanizing. It is the material used to touch-up and or repair hot-dipped galvanized surfaces, providing barrier protection and some cathodic protection (if the concentration of zinc is above 94 % in dry film thickness).
Zinc smelting – It is defined as the process of extracting zinc metal from its ores, mainly through methods such as roasting zinc concentrates to produce zinc oxide, which is then reduced by carbon in furnaces at high temperatures. This process includes various techniques like blast furnace processing and use of vertical retorts to efficiently produce zinc.
Zinc solder – It is the material which is used to touch-up and / or repair hot-dip galvanized surfaces.
Zinc spelter – It typically refers to impure zinc, frequently in the form of slabs, got from the reduction of zinc ores. It is a commercially available form of zinc but contains impurities like lead and sometimes copper. Zinc spelter can also refer to a zinc-lead alloy which resembles bronze in appearance when aged.
Zinc stearate – It is a fine, white powder which acts as a lubricant. It is used to reduce friction during the pressing and compacting of metal powders, which helps prevent die wear and improves the flow of powder into the die cavity. This results in a more consistent and defect-free powder compact, known as a green compact.
Zinc sulphate – It is a chemical compound with the formula ZnSO4, normally known as white vitriol. It is an inorganic compound. It forms hydrates ZnSO4.nH2O, where ‘n’ can range from 0 to 7. All are colourless solids. The most common form includes water of crystallization as the heptahydrate, with the formula ZnSO4·7H2O.
Zinc sulphide (ZnS) – It is a naturally occurring inorganic compound with the chemical formula ZnS. It is a white, crystalline material which is normally found as the mineral sphalerite. Pure zinc sulphide is white, but it can appear black because of the impurities. It has several applications, including use as a pigment, in optics, and as a component in electronic devices because of its luminescent properties.
Zinc sulphide films – These are thin layers of the compound zinc sulphide (ZnS) which are used in several opto-electronic and optical applications because of their unique properties. These films are known for their wide band-gap, high refractive index, and ability to transmit light in the visible and infrared spectrum.
Zinc sulphide nano-particles – These nano-particles are defined as nano-scale structures of zinc sulphide which show unique morphologies, such as one-dimensional nano-wires and three-dimensional micro-spheres, and possess significant opto-electronic properties, making them suitable for applications in solar cells and photo-detectors.
Zinc worms – These are surface imperfections, characteristic of high-zinc brass castings, which occur when zinc vapour condenses at the mould / metal interface, where it is oxidized and then becomes entrapped in the solidifying metals.
Zincrometal – It is a steel coil-coated product consisting of a mixed-oxide underlayer containing zinc particles and a zinc-rich organic (epoxy) topcoat. It is weldable, formable, paintable, and compatible with normally used adhesives. Zincrometal is used to protect outer body door panels in automobiles from corrosion.
Zircon – It is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium (IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1-y, REEy)(SiO4)1-x(OH)4x-y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 % to 4 %. The crystal structure of zircon is tetragonal crystal system. The natural colour of zircon varies between colourless, yellow-golden, red, brown, blue, and green.
Zirconia – It is also known as zirconium dioxide (ZrO2). It is a white crystalline oxide of zirconium. It is a versatile material with applications ranging from jewelry to dental implants and even nuclear reactors. It is also known as a popular diamond simulant called cubic zirconia.
Zirconia grain stabilization – It refers to the process of preventing the phase transformation of zirconium di-oxide (zirconia) from its tetragonal or cubic form to its monoclinic form at lower temperatures by adding a stabilizing agent like yttria. This transformation can cause a substantial volume expansion and lead to cracking and failure of the material. By stabilizing the tetragonal or cubic phase, the material’s strength and toughness are improved, making it more durable and suitable for several applications.
Zirconia refractories – These are refractories mainly composed of zirconium oxide (ZrO2). They are frequently used for glass furnaces since they have low thermal conductivity, are not easily wetted by molten glass and have low reactivity with molten glass. These refractories are also useful for applications in high temperature construction materials.
Zirconia toughened alumina (ZTA) – It is a composite material made from alumina and zirconia. It combines the outstanding characteristics of both materials. Compared to conventional alumina, zirconia toughened alumina possesses superior hardness, higher flexural strength, and similar density. Compared to conventional zirconia, it possesses a lower coefficient of linear thermal expansion and higher thermal conductivity. By leveraging these features, zirconia toughened alumina has been widely adopted in milling parts and wear-resistant parts which need cooling. Zirconia-toughened is frequently used in structural applications, cutting tools, and medical devices.
Zirconium (Zr) – It is a chemical element having atomic number 40. Pure zirconium is a lustrous transition metal with a greyish-white colour that closely resembles hafnium and, to a lesser extent, titanium. It is solid at room temperature, ductile, malleable and corrosion-resistant. The mineral zircon is the most important source of zirconium. Besides zircon, zirconium occurs in over 140 other minerals, including baddeleyite and eudialyte. Majority of zirconium is produced as a byproduct of minerals mined for titanium and tin. Zirconium forms a variety of inorganic compounds, such as zirconium dioxide, and organometallic compounds, such as zirconocene dichloride. Five isotopes occur naturally, four of which are stable. The metal and its alloys are mainly used as a refractory and opacifier. The properties of zirconium indicate that it is ductile and has useful mechanical properties similar to those of titanium and austenitic stainless steel. Zirconium has excellent resistance to several corrosive media, including super-heated water, and it is transparent to thermal energy neutrons. Because of these properties, zirconium is used in water-cooled nuclear reactors as cladding for uranium fuel. In 1958, zirconium became available for industrial use and began to supplant stainless steel as a fuel cladding in commercial power station nuclear reactors. Also, the chemical-processing industries began to use zirconium in several severe corrosion environments. Zirconium also finds uses in flashbulbs, biomedical applications and water purification systems. Zirconium alloys are used to clad nuclear fuel rods because of their low neutron absorption and strong resistance to corrosion, and in space vehicles and turbine blades where high heat resistance is necessary.
Zirconium alloys – These are defined as metallic materials mainly composed of zirconium, frequently alloyed with elements such as tin, niobium, chromium, iron, and hafnium. These alloys are used extensively in the nuclear industry for applications like fuel cladding, fuel channels, and structural components in water-cooled reactors. These alloys, including Zircaloy-1, Zircaloy-2, and Zircaloy-4, are selected for their superior corrosion resistance and mechanical properties under reactor conditions.
Zirconium alloy welding – Zirconium alloys are weldable with procedures and equipment are similar to those used for welding titanium and austenitic stainless steels. Zirconium has a low coefficient of thermal expansion, which contributes to low distortion during welding. Because of the reactivity of zirconium with oxygen, nitrogen, and hydrogen, the metal is to be shielded during welding with high-purity inert gas or a good vacuum. Also, zirconium is to be free of oil, grease, and dirt to avoid the dissolving of carbon-containing and oxygen-containing materials, which can embrittle the metal or create porosity and can reduce the corrosion-resistant properties of the metal. Zirconium and its alloys are available in two general categories namely commercial grade and reactor grade. Commercial-grade zirconium designates zirconium which contains hafnium as an impurity. Reactor-grade zirconium designates zirconium from which majority of the hafnium has been removed to make it suitable for nuclear reactor applications. Since pure zirconium has relatively low mechanical properties, different alloying elements are added to enhance its mechanical properties. Zirconium and its alloys are available in plate, sheet, bar, rod, and tubing form in a variety of material specifications.
Zirconium alloy welding process – Zirconium alloys are highly reactive to oxygen and nitrogen in air at high temperatures. Hence, the selected welding processes and procedures are to be capable of shielding the weldment and heat-affected zones (HAZ) from contamination. The use of fluxes is normally avoided, since reactivity with the chemicals in the fluxes causes brittleness and can reduce the corrosion resistance of zirconium weldments. The welding processes which can be used for welding are (i) gas tungsten arc welding, (ii) gas metal arc welding, (iii) plasma arc welding, (iv) electron beam welding, (v) laser beam welding, (vi) friction welding, (vii) resistance welding, (viii) resistance spot welding, and (ix) resistance seam welding. The selection of a welding process depends on several factors, e.g., weld joint, tensile and corrosion-resistant property requirements, cost, and design configuration. Gas-tungsten arc welding is very widely used process for joining zirconium alloys. It uses techniques similar to those used for welding stainless steel, i.e., the direct current power supply is connected for straight polarity (electrode negative, DCEN). Two desirable features are a contactor for making and breaking the arc and high-frequency arc starting. Plasma arc welding is also commonly used, especially for autogenous welding of butt joint thicknesses from 3 millimeters to 1.5 millimeters. Gas-metal arc welding is occasionally used for joint thicknesses from 3 millimeters or more, because of its more-rapid weld time and the consequent savings in shielding gas and production time. Weld quality is more difficult to maintain, because of weld spatter and arc instability, which result in weld contamination and weld defects. Electron-beam welding is rarely used, because of high equipment operating cost as well as weld chamber size limitations. Laser-beam welding has had very limited use in joining zirconium and has been applied mainly in nuclear reactors. Friction welding is used to join zirconium tubes to zirconium rods, as well as to dissimilar metal alloys (e.g., zirconium to stainless steel) for heat-exchanger applications. Resistance welding is especially useful for the seam or spot welding of thin sheets, since no shielding is needed.
Zirconium carbide (ZrC) – It is a hard, refractory ceramic material known for its high melting point, high thermal and electrical conductivity, and strong chemical resistance. It has a metallic gray colour and a cubic crystal structure. It is frequently used in aerospace and nuclear applications because of its strength and ability to maintain properties at high temperatures.
Zirconium carbide cermets -These are composite materials combining the hardness of zirconium carbide (ZrC) ceramic with the toughness and ductility of a metallic component, typically a metal like nickel, cobalt, or tungsten. These materials are engineered to leverage the beneficial properties of both ceramic and metallic phases, resulting in materials with high temperature strength, wear resistance, and fracture toughness.
Zirconium casting – It refers to the process of creating zirconium or zirconium alloy components by melting the metal and pouring it into a mould to solidify into the desired shape. This technique is similar to titanium casting, but zirconium alloys are more reactive at high temperatures, needing careful process control. Zirconium casting utilizes two melting methods namely vacuum arc skull melting and vacuum induction melting. Both furnace systems are capable of melting all reactive alloys. Castings can be produced with the receiving moulds in a static mode as well as by centrifugal casting. Centrifugal casting is accomplished by mounting the moulds on a turntable. This setup utilizes a centre sprue with a runner system to feed from the outside of the mould in. The mould is filled against the centrifugal forces, allowing a slower fill rate and reducing the potential for entrapped gases in the casting.
Zirconium di-boride (ZrB2) – It is a highly covalent refractory ceramic material with a hexagonal crystal structure. Zirconium di-boride is an ultra-high temperature ceramic (UHTC) with a melting point of 3,246 deg C. This along with its relatively low density of around 6.09 grams per cubic centimeters (measured density can be higher because of hafnium impurities) and good high temperature strength makes it a candidate for high temperature aerospace applications such as hypersonic flight or rocket propulsion systems. It is an unusual ceramic, having relatively high thermal and electrical conductivities, properties it shares with iso-structural titanium di-boride and hafnium di-boride. Zirconium di-boride parts are normally hot pressed (pressure applied to the heated powder) and then machined to shape. Sintering of zirconium di-boride is hindered by the material’s covalent nature and presence of surface oxides which increase grain coarsening before densification during sintering. Pressure-less sintering of zirconium di-boride is possible with sintering additives such as boron carbide and carbon which react with the surface oxides to increase the driving force for sintering but mechanical properties are degraded compared to hot pressed zirconium di-boride. Additions of around 30 volume percent silicon carbide (SiC) to zirconium di-boride is frequently done to improve oxidation resistance through silicon carbide creating a protective oxide layer which is similar to aluminum’s protective alumina layer.
Zirconium oxide based cermets – Zirconia is a ceramic material which can be bonded with metal to give useful refractory products. Even when combined with only small quantities of metal, such as 5 % to 15 % titanium, strong and thermal shock resistant materials suitable for crucibles to melt rare and reactive metals can be produced. If the zirconium oxide is combined with molybdenum, the resulting cermet shows excellent corrosion resistance against molten steel, in addition to high-temperature strength and limited sensitivity to thermal shock, especially when the metal content is around 50 % by volume. Thermocouple sheaths for temperature measurements of metallic melts, extrusion dies used for forming non-ferrous metals, and wear resistant parts made from these cermets with somewhat higher ceramic content, such as 60 % by volume, are some of the applications.
Zirconium oxide refractory – It consists of refractory products consisting substantially of zirconium di-oxide. It is known for their high temperature resistance and chemical stability. Zirconium oxide casting refractories are used in several high-temperature applications, including furnace linings, crucibles, and casting nozzles, because of their exceptional properties.
Zirconium powder – It is a fine, particulate form of the metallic element zirconium. It’s typically a grayish-white or bluish-black powder, depending on its purity and form, and is characterized by its high flammability in its dry state. Zirconium powder can be produced through various methods and is used in a wide range of applications, including pyrotechnics, explosives, and as a component in alloys.
Zirconium oxy-chloride (ZrOCl2) – It is a chemical compound used in textile treatments, particularly in fire retardant applications, frequently combined with citric acid and hydrochloric acid. It is utilized to improve the flame resistance of materials like wool fabric under specified conditions.
Zirconium titanate – It is also called lead zirconate titanate (PZT). It is defined as a ceramic perovskite material. It is known for its significant piezo-electric properties, which enable it to change shape when an electric field is applied. It is widely used in many industrial applications because of its high performance, low loss, and versatility in fabrication into different forms.
Zircon refractory – It consists of refractory products consisting substantially or entirely of crystalline zirconium orthosilicate (ZrSiO4). Zircon refractories are specialized ceramic materials known for their exceptional resistance to high temperatures and chemical corrosion. These materials are widely used in industries like metallurgy, glass manufacturing, and ceramics because of their ability to withstand harsh conditions without substantial degradation.
ZK60 alloy – It refers to a magnesium alloy which is known for its limited precipitation hardening and is improved in strength through the co-addition of minor elements such as calcium (Ca) and erbium (Er), resulting in ultra-high tensile and yield strengths.
Z-mill – It is also known as a Sendzimir mill. It is a type of cold rolling mill known for its ability to produce high-quality, thin-gauge steel sheets and plates with precise tolerances and surface finishes. It achieves this through a unique design featuring multiple small-diameter work rolls backed by a series of larger backup rolls. This configuration allows for high rolling forces and precise control over the rolling process, resulting in minimal surface defects and consistent thickness.
Zonal safety analysis (ZSA) – It is defined as a tool in the system safety process which examines the proximity aspects of individual system installations and assesses the potential for mutual influence between systems installed in close proximity.
Zone – It typically refers to a defined area or region within a system, structure, or process which is distinguished by specific characteristics or functionalities. These zones can be created for different purposes, such as designating different areas within a building for specific uses, defining areas of risk in hazardous environments, or establishing regions with specific regulations or tolerances. In geology, zone is an area of distinct mineralization. Zone is also any group of crystal planes that are all parallel to one line, which is called the zone axis.
Zone axis – In crystallography, it is a crystallographic direction which is parallel to the intersection line of two or more crystal planes. Essentially, it is the direction along which these intersecting planes align.
Zone control – It is a feature in conveyor systems where different zones of the conveyor can be controlled independently, allowing for better energy efficiency and product handling.
Zoned heating – It refers to a system that divides a furnace into multiple temperature-controlled areas (zones) to optimize heating efficiency. Instead of heating the entire furnace to a single temperature, zoned systems allow for different temperatures in different areas, based on needs and preferences. This approach can lead to substantial energy savings.
Zone melting – It means highly localized melting, normally by induction heating, of a small volume of an otherwise solid metal piece, normally a metal rod. By moving the induction coil along the rod, the melted zone can be transferred from one end to the other. In a binary mixture where there is a large difference in composition on the liquidus and solidus lines, high purity can be attained by concentrating one of the constituents in the liquid as it moves along the rod.
Zone of oxidation – It is the upper portion of an ore-body which has been oxidized.
Zone, primary combustion – In this zone of combustion, the primary combustion takes place. It is defined as the region within a combustion chamber where a portion of the air is mixed with fuel at an optimal air / fuel ratio, typically around 15:1, for facilitating efficient burning of the fuel. This zone is characterized by a toroidal vortex that stabilizes the flame and promotes the rapid ignition of fuel droplets.
Zone refining – It is a technique which is used to purify materials, especially metals and semiconductors, by repeatedly melting and solidifying a small zone of the material. Impurities tend to concentrate in the molten zone, leaving behind a purer solid as the zone moves. This process is repeated multiple times to achieve high levels of purity.
Zones concept, sintering – Typical sintering furnaces can be thought of as having three or more interconnected zones (depending on the powder material being sintered), each with a separate function. The sintering process consists of several sequential phases, each needing a unique combination of temperature, time and atmosphere composition, flow, direction, and circulation. Each phase of the sintering process occurs in a specific zone of the furnace. Separating these zones and phases conceptually improves design flexibility. A close match between the temperature and atmosphere of each zone and the function of each phase results in an optimum overall sintering process. In a single system, the base nitrogen can be modified with other gases or active ingredients to produce an appropriate and optimum atmosphere composition for each sintering phase before introduction into proper furnace zone.
Zone segregation – It refers to the separation of different groups or elements into distinct areas or zones. This can apply to different contexts, including social groups, waste management, and even network security.
Zone segregation, steel ingot – It refers to the uneven distribution of chemical elements or phases within the solidified metal, creating distinct zones with varying compositions. This occurs during the solidification process when some elements prefer to remain in the liquid phase while others solidify into the metal structure, leading to localized variations in composition. Zone segregation in the steel ingots cannot be eliminated completely by rolling or forging, though the shape of the segregated zone possibly can be changed, e.g., square-shape segregation frequently appears in the cross section of hot rolled steel. Hence, heat treatment distortion Is intensified because of this segregation.
Zone, sintering – In powder metallurgy, it consists of highly localized, progressive heating during sintering to produce a desired grain structure, such as grain orientation, and directional properties without subsequent working.
Zones, reheating furnace – A reheating furnace, used in steel and metalworking industries, is typically divided into three or more zones to gradually heat metal stock to the desired temperature. These zones are namely preheating zone, heating zone, and soaking zone. Each zone has specific functions and temperature profiles. Some furnaces can have more than one heating zone. In the preheating zone, the charged steel material is preheated. The role of the preheating zone is to increase the temperature of the steel material progressively. Slow heating of the steel surface initially is necessary for the control of the thermal stresses in the steel material. In the heating zone the surface temperature of the steel material is raised rapidly. The majority of heat absorption by steel material is accomplished in this zone. In the soaking zone, the internal temperature of the steel material is controlled so as to have as far as possible a uniform temperature throughout the cross section of the steel material. The temperature of this zone is progressively increased so as to have the target or desired discharging temperature for the steel material. In the reheating furnace, the major amount of heating takes place in the heating zone. The temperature uniformity up to desired limits between the core and the surface of the steel material is achieved in the soaking zone. The flue gases move in a direction opposite to that of the steel material and thus ensures considerable amount of waste heat recovery by convection in the preheating zone. Preheating zone is also sometimes called the recuperative zone. The velocity and the retention time of the exhaust gases in the furnace are important for the effective transfer of its sensible heat to the steel material.
Zoning – It is a device of land use planning. The word is derived from the practice of designating permitted uses of land based on mapped zones which separate one set of land uses from another. Zoning can be use-based (regulating the uses to which land can be put) or it can regulate building height, lot coverage and similar characteristics or some combination of these.
Zoom – In image processing, zoom refers to the geometric transformation which magnifies or reduces the size of an image. It is a way to make an image appear larger or smaller, frequently to reveal details or fit it within a display area. Zooming can be achieved through different methods, including optical zoom (using lens movement) and digital zoom (image processing).
Zoom scope sight – It is an optical device which uses a telescopic lens system to magnify a distant target. The ‘zoom’ aspect refers to the ability to adjust the magnification, typically through a variable power setting, to bring the target closer or further away visually.
Z-phase – It refers to different things depending on the context. In materials science, it typically describes a specific phase in metal alloys, frequently a complex nitride, or a phase formed in sodium-ion battery cathodes. In encoder systems, the Z-phase signal is a reset or origin signal. It can also refer to a phase in zeolites or a concept in photo–catalysis.
Z-pins – These are a type of reinforcement used in composite materials which improve strength in the through-the-thickness direction, improving resistance to delamination and enabling the creation of joints capable of withstanding higher mechanical loads.
Z-section – It is a structural component shaped like the letter ‘Z’. It is used mainly in construction for supporting roofs and walls. It is characterized by a central web and two flanges extending at opposing angles, providing strength and flexibility, especially in metal building framing. Z-sections are frequently used as purlins (for roofs) and girts (for walls) to support cladding and distribute loads evenly. The Z-shape provides a good strength-to-weight ratio and resistance to bending and torsion, making it suitable for spanning between main structural elements like rafters or trusses.
Z-transform – It is a mathematical operation which converts a set of evenly spaced measurements of an analog signal into a series of frequency components. It is a mathematical tool used to convert a discrete-time signal (a sequence of numbers) into a complex frequency-domain representation. It is analogous to the Laplace transform for continuous-time signals and is particularly useful for analyzing discrete-time systems and solving difference equations.
Zwitterion – It is also called an inner salt or dipolar ion. It is a molecule which contains an equal number of positively and negatively charged functional groups. Some zwitterions, such as amino acid zwitterions, are in chemical equilibrium with an uncharged ‘parent’ molecule.
Zwitterionic materials – These materials are defined as – that contain both positively and negatively charged groups, resulting in an overall neutral charge. They show strong hydrophilicity and antifouling properties because of the ionic structuring of water, which creates a hydrated layer which repels foulants.
Zwitterionic surfactant – It is defined as an amphiphilic organic compound which possesses both hydrophobic groups in its tail and hydrophilic groups in its head, which can substantially reduce interfacial tension in oil recovery applications.
Zylon – It is is a trademarked name for a high-performance synthetic polymer material, specifically a range of thermoset liquid-crystalline poly-oxazole. Its IUPAC (International Union of Pure and Applied Chemistry) name is poly (p-phenylene-2,6-benzobisoxazole. In generic usage, the fibre is referred to as PBO. Zylon has 5.8 gigapascals of tensile strength, which is 1.6 times that of Kevlar. Additionally, Zylon has a high Young’s modulus of 270 gigapascals, meaning that it is stiffer than steel. Like Kevlar, Zylon is used in a number of applications which need very high strength with excellent thermal stability.
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