Industrial grade, 99.7% Feed grade, 99.9% Cosmetic grade, 99.9% Food additive, 99.9%Zinc oxide CAS 1314-13-2

 What is Zinc Oxide? How does it work?

Zinc oxide (ZnO) is the most important industrial compound of zinc, a white powder. It is the vulcanizing activator in car tires, the soft magnetic ferrite material in transformers of mobile phone chargers, the core material of varistors in surge protectors, the white pigment in latex paint, and the friction material in brake pads—from the cars we drive every day to mobile phone chargers, from latex paint on walls to batteries in remote controls, industrial-grade zinc oxide contributes to all of them.

Basic information: Molecular formula ZnO, molecular weight 81.38, CAS number 1314-13-2, EC number 215-222-5; It exists naturally as zincite, and is industrially produced by indirect methods (French method, high-temperature evaporation and oxidation of zinc ingots, purity ≥99.7%) or direct methods (US method, reduction and oxidation of zinc ore/zinc-containing materials).

Physically, it is a white powder (turns yellow upon heating and returns to its original color upon cooling), odorless; density 5.606 g/cm³; melting point approximately 1975℃, boiling point approximately 2360℃ (sublimes at high temperatures); almost insoluble in water, soluble in dilute acids and alkalis (amphoteric oxide); refractive index approximately 2.0 (strong hiding power); high thermal conductivity and high specific heat capacity; belongs to the hexagonal crystal system of wurtzite.

Chemically, zinc oxide is an amphoteric oxide: it reacts with acids to form zinc salts (with hydrochloric acid to form zinc chloride) and with bases to form zincates (with sodium hydroxide to form sodium zincate); at high temperatures, it reacts with organic acids such as stearic acid to form zinc soaps; and it reacts with high-temperature solid-state substances such as iron oxide to form zinc ferrites. It exhibits semiconductor properties with a band gap of approximately 3.37 eV, making it one of the most piezoelectric materials. Storage must be moisture-proof and avoid direct mixing with strong acids.

Grade Definition: This article discusses industrial-grade zinc oxide—specifications used in industrial applications such as rubber, coatings, ceramics, electronics, batteries, and catalysts. It is categorized by production method into indirect method (for electronics and rubber) and direct method (for ceramics, coatings, and chemicals). Other grades include cosmetic grade (UV filters in sunscreens), feed grade (for animal zinc nutrition), food grade (for nutritional fortification), and reagent grade (for analytical chemistry). This article focuses on industrial-grade applications.

From the perspective of its mechanism of action, industrial-grade zinc oxide plays an irreplaceable role due to its "zinc ion coordination activation + semiconductor/piezoelectric electronic properties + high refractive index scattering". The mechanisms of action in different applications are as follows:

1.Rubber vulcanization activation mechanism

Zinc oxide reacts with stearic acid to form zinc soap, which then reacts with an accelerator to form a zinc vulcanization intermediate. This intermediate is a key medium for the cross-linking of sulfur with diene rubber to form sulfur bonds, thereby accelerating vulcanization, increasing cross-linking density, and improving wear resistance and thermal conductivity.

2.Nonlinear mechanism of varistors

The grain boundaries of ZnO form a potential barrier. Under normal voltage, the resistance is extremely high and the current is extremely small. When the voltage is over-voltage, the grain boundary barrier breaks down, the resistance drops sharply, and the current is discharged, thereby absorbing surge energy and protecting electronic equipment.

3.Piezoelectricity and surface acoustic wave mechanism

The non-centrosymmetric structure of wurtzite makes ZnO one of the most piezoelectric materials. Mechanical deformation generates electric charge, and electrical signals excite mechanical vibrations, which can be used to make surface acoustic wave (SAW) filters and piezoelectric transducers.

4.Soft magnetic ferrite mechanism

Zinc oxide reacts with iron oxide and manganese oxide in a high-temperature solid-state reaction to form a Mn-Zn ferrite spinel structure, which has high magnetic permeability and low loss characteristics, making it the core magnetic core material for switching power supply transformers, inductors and EMI filters.

5.Semiconductors and the mechanism of transparent conductivity

A wide bandgap semiconductor with a bandgap of approximately 3.37 eV, when doped with aluminum (AZO), achieves both conductivity and light transmittance, making it suitable for use as a transparent conductive film; its photoconductivity is used in photoconductive coatings for electrostatic copying, and its ultraviolet response is used in detection devices.

6.Pigments and Rust Prevention Mechanism

With a refractive index of approximately 2.0, it exhibits strong visible light scattering and high hiding power, providing whiteness and coverage when used as a white pigment. It is weakly alkaline, which can neutralize acidic components in coatings, thus inhibiting corrosion and preventing rust, while also suppressing mold growth and preventing yellowing.

7.Photocatalysis and antibacterial mechanism

Excited by ultraviolet light to generate electron-hole pairs, they react with water and oxygen to generate reactive oxygen species to degrade organic matter, and the slow release of zinc ions to destroy microbial cells, thereby achieving photocatalytic purification and long-term antibacterial effect.

To summarise, industrial zinc oxide is the “king of multifunctional inorganic materials”. Its zinc ion coordination activation, semiconductor/piezoelectric electronic properties, and high refractive index scattering, are used in many fields including tyre rubber, varistors, soft magnetic ferrites, latex paints, brake pads and photocatalytic coatings, covering the fields of rubber, electronics, magnets, coatings, ceramics, chemicals and batteries.

 What are the applications of industrial-grade Zinc Oxide?

Industrial-grade zinc oxide has applications in rubber, magnetic materials, electronic components, semiconductors and optoelectronics, coatings and pigments, ceramics and enamels, glass, batteries, chemical catalysis, plastics, flame retardants, textiles, environmental protection, and friction lubrication, among other fields.

1. Vulcanisation and reinforcement activators of rubber (important applications in rubber industry)

Uses: Tires, rubber products.

Related Products: Tires for cars and bicycles, conveyor belts and gearbox belts, hoses, seals and O-rings, rubber shoe soles, latex products (gloves, balloons, condoms), rubber adhesives, rubber gaskets, etc.

Why it works for this purpose: Zinc oxide reacts with stearic acid to form zinc soap, and then forms a zinc vulcanisation intermediate with an accelerator. This intermediate is an important medium for sulphur cross-linked diene rubber, which promotes vulcanisation, increases the cross-linking density, and enhances wear resistance, thermal conductivity, and ageing resistance. It is an important vulcanisation activator for rubber formulations.

2. Soft magnetic ferrite materials (core application in magnetic material industry)

Areas of application: Magnetic materials and electronic power supplies.

Corresponding products: Mn-Zn soft ferrite cores, switching power supply transformer cores, inductor cores, EMI filter rings, broadband transformer cores, antenna cores, ferrite beads, etc.

Why suitable for this application: At high temperatures, zinc oxide reacts with iron oxide and manganese oxide to form a Mn-Zn ferrite spinel structure which has high permeability, high saturation magnetic induction and low loss. It is the basic raw material for transformer and filter cores in switch power supplies, chargers, and variable frequency appliances.

3. Varistors and surge arresters (main applications in the electronic components industry)

Application fields: Electronic protection devices, power protection.

Related Products: ZnO varistors (MOVs), surge protectors (SPDs), power surge protectors, surge arrestor valves, power system surge arresters, communication equipment surge protection modules, over-voltage protection components for household appliances, etc.

Reason why it is suitable for this application: The nonlinear current-voltage characteristics are due to the grain boundary barrier of ZnO. It gives high resistance insulation at normal voltage and low resistance conduction during overvoltage to discharge surge current and clamp voltage. It has the advantages of fast response, large current carrying capacity and long life, and it is the core component for surge protection and overvoltage protection of electronic equipment.

4. Piezoelectric and surface acoustic wave devices (electronics sector)

Application areas: Acoustic devices, radio frequency communication.

Other Related Products: Surface acoustic wave (SAW) filters, RF front-end filters, piezoelectric transducers, ultrasonic transducers, piezoelectric sensors, SAW resonators, microelectromechanical systems (MEMS) piezoelectric devices, etc.

Why it fits this application: Zinc oxide wurtzite is a non-centrosymmetric material and is one of the most piezoelectric materials. Electrical signals can excite mechanical vibrations and produce surface acoustic waves. This allows for the selection of frequencies and signal processing. It is an important material for RF filters of mobile phones and ultrasonic transducers.

5. Semiconductor and optoelectronic device material (semiconductor and optoelectronic industry area)

Application areas: Optoelectronics, semiconductor devices.

Corresponding products: Transparent conductive films of AZO (aluminium doped zinc oxide), Active layers for thin film transistors (TFTs), LED and OLED related materials, Thin film solar cells, Ultraviolet detectors, Gas sensors, Photoconductive coated paper for electrostatic copying, Photosensitive materials for electrophotography, etc.

What is good about it for this application: Aluminium-doped ZnO is a wide bandgap semiconductor with a bandgap of ~3.37 eV, which also has high light transmittance and conductivity, so it is a good alternative to ITO. It is used for electrostatic copying because of its photoconductivity, and its ultraviolet response is used for detection, so it is an important functional material for transparent electronic and optoelectronic devices.

6. White pigments and anti-rust primers (pigment and coatings industries)

Application: Coatings, papermaking, and pigment industry.

Matching products: Zinc white pigment, latex paint and water-based paint, anti-rust primer, marine and container coating, metal anti-corrosion coating, papermaking filler, printing and dyeing colouring material, match industry filler, anti-mildew and anti-yellowing coating, etc.

Why it works for this purpose: It has a refractive index of about 2.0, has strong scattering, good hiding power, long lasting whiteness, and does not turn yellow or grow mould; it is weakly alkaline, can inhibit corrosion and prevent rust, so it is a multi-functional component in coating systems that combines pigment, rust prevention and mildew prevention functions.

7. Ceramic glazes and enamels (ceramic industry)

Application fields: Architectural ceramics and enamel ware for daily use.

Related products: Glazes for tiles, glazes for sanitary ware, artistic ceramic glazes, glazes and enamels for porcelain, enamel cookware and enamel products, ceramic colourant fluxes, etc.

Why it works for this purpose: Zinc oxide acts as a flux in glazes and enamels, reducing firing temperature, increasing whiteness and opacity, improving glaze gloss and thermal expansion matching, and can be blended with metal oxides to produce colour. It is a common ingredient in ceramic and enamel formulations.

8. Raw materials for the glass industry (subsector of the glass industry)

Application Areas: Glass Manufacturing.

Related Products: Optical glass, special functional glass, microcrystalline glass, glass clarifying and decolorising agents, electronic glass, lighting glass, etc.

Why it works for this purpose: Zinc ions have a medium radius and high polarisability. Their incorporation into the glass network can change the refractive index, lower the thermal expansion, and improve the melting property and chemical stability. It is a constituent in the composition of optical and special glasses.

9. Battery and energy storage materials (battery industry sector)

Application fields: Battery and energy storage.

Related products: zinc-air battery negative material, nickel-zinc (Ni-Zn) battery, zinc electrode additive in alkaline battery, lithium-ion battery negative material, zinc flow battery, energy storage electrode active material, etc.

Why it works for this purpose: ZnO can be converted into porous zinc electrode active materials, thus increasing the specific surface area and cycle stability of the electrode. Zinc-air and nickel-zinc batteries are important directions of mercury-free and environmentally friendly batteries, and ZnO is also used as anode modifiers in lithium batteries.

10. Catalysts and desulfurizing agents (industry of chemical catalysis)

Applications: Petrochemical and syngas industries.

Related products: Methanol synthesis catalysts (Cu/ZnO/Al₂O₃), carbon monoxide shift catalysts, desulfurizing and dechlorinating agents, hydrogenation catalyst supports, syngas conversion catalysts, etc.

Why it is suitable for this application: Zinc oxide can provide active sites and support structure, and synergistically catalyse the hydrogenation of CO/CO₂ to methanol with copper, and can absorb hydrogen sulphide as a highly efficient desulfurizing agent, making it a key catalytic material in the coal chemical and syngas industries.

11. Functional fillers for plastics (plastic industry)

Application fields: Plastics and polymer materials.

Applicable products: UV-shielding plastics, antibacterial plastic products, plastic films and agricultural films, engineering plastics modified fillers, transparent plastic additives, synergistic components for plastic heat stabilisers, etc.

How it works for this purpose: Zinc oxide absorbs and shields against ultraviolet rays, which prevents plastic ageing and degradation; zinc ions are slowly released, giving antibacterial properties; and nano-zinc oxide can also strengthen plastics. It is a very common filler for anti-ageing and functionalised plastics.

12. Synergists of flame retardants (in the context of flame retardant materials)

Uses: Flame retardant materials, Cables.

Corresponding products: Flame retardant wire and cable sheathing materials, flame retardant plastics and rubbers, flame retardant coatings, flame retardant conveyor belts, fireproof sealing materials, etc.

Why does it work for this purpose: Zinc oxide synergises with halogenated flame retardants and metal hydroxide flame retardant systems to promote char formation and inhibit the release of toxic smoke, while improving the oxygen index and flame retardant rating. It is an important synergist in the formulation of wires, cables and flame retardant materials.

13. Antibacterial finishing of textiles and functional fibres (textile industry)

Application areas: Functional textiles and fabrics.

Matching products: Antibacterial socks, pants, sports functional fabrics, nano-antibacterial fibre, UV-protection textiles, smart textiles, etc.

How it works for this purpose: Zinc oxide ions are slowly released and destroy microbial cells; under ultraviolet light, it produces reactive oxygen species to enhance its antibacterial properties; nano-zinc oxide can be attached to fibres to create durable antibacterial, deodorising and UV-protective functions, thus becoming a core finishing material for functional textiles.

14. Photocatalysis and environmental purification materials (Environmental protection field)

Applications: Environmental remediation and surface modification applications.

Other products: photocatalytic air purifier filters, photocatalytic degradation coatings, self-cleaning exterior wall coatings, interior wall coatings with antibacterial properties, wastewater treatment photocatalysts, deodorising materials, etc.

How it works for this purpose: Ultraviolet light excites zinc oxide to create electron-hole pairs that react with water and oxygen to form reactive oxygen species that degrade organic pollutants and bacteria, achieving air purification, self-cleaning and antibacterial properties. It is an important photocatalyst for eco-friendly purification materials.

15. Friction materials and grease additives (in the area of friction and lubrication)

Applications: Automotive parts, lubricating grease.

Other products: Automotive brake pad friction materials, clutch friction plates, high temperature greases, anti-seize lubricants, gear lubrication additives, friction modifiers, etc.

Why it is suitable for this application: Zinc oxide is resistant to high temperatures and wear and has good thermal conductivity. In friction materials it acts as a filler for stabilising the coefficient of friction and minimising wear. For lubricating greases it serves as an extreme pressure wear-resistant additive to ensure reliable operation of braking and lubrication systems.

To summarise, the “king of multifunctional inorganic materials” industrial-grade zinc oxide (ZnO, CAS 1314-13-2) is known for its zinc ion coordination activation, semiconductor/piezoelectric electronic properties, and high refractive index scattering to mature applications in 15 major sectors such as, but not limited to, rubber vulcanisation activation, soft magnetic ferrites, varistors, piezoelectric surface acoustic waves, semiconductor optoelectronics, white pigments and rust prevention, ceramic glazes and enamels, glass, battery energy storage, catalysts and desulfurization, functional fillers for plastics, flame retardant synergy, textile antibacterial properties, photocatalytic purification, and friction lubrication. The main consumption area is rubber vulcanisation activators and the fastest growing electronic applications are soft magnetic ferrites, varistors and battery materials. They also do well with tires, power supply equipment, surge protectors and batteries—all common items. Note: Prolonged breathing of large quantities of zinc oxide dust may cause “metal fume fever.” Avoid contact with skin. Applications in cosmetics, animal feed and food are subject to the relevant grade specifications and are outside the scope of this industrial grade description.