How is the Zirconia Industry Laid Out?

Globally, zirconia producers are mainly concentrated in a few countries, mainly including China, Japan, France, the United Kingdom, the United States, and Australia. Companies with comprehensive zirconia industrial layout include Saint-Gobain, Japan’s Tosoh, Japan’s First Element, Showa Denko, France’s Suvi, and Japan’s Sumitomo Osaka Cement. Among them, the main business of First Element is zirconium-based, and most of the other companies are large-scale integrated enterprises.

With zirconia as the main component, after adding rare earth elements (mainly cerium oxide) and other oxides, composite zirconia powders with different performance characteristics can be formed. The nature of the composite zirconia depends on the type of material or crystal structure to which it is combined. Depending on the specific needs of the application, different formulations of composite zirconia materials with different properties can be prepared using different formulations.

zirconia

In general, zirconia ceramics are divided into three categories: PSZ partially stabilized zirconia, also known as ceramic steel (with superior impact resistance); TZP tetragonal polycrystalline zirconia (better mechanical strength and fracture toughness); FSZ fully stabilized zirconia, crystalline phase cubic phase, with high temperature conductivity, but high thermal expansion coefficient and poor thermal shock resistance.

Catalyst

Since zirconia is the only metal oxide that has both acidic and basic and oxidizing and reducing properties and is also a p-type semiconductor, it is easy to generate oxygen vacancies. As a catalyst carrier, it can interact with the active component, so its supported catalyst has more excellent properties than other materials supported catalysts.

Precise ceramic parts

Zirconia ceramics can have excellent mechanical properties and fracture toughness, chemical resistance, and biocompatibility, so you can see the back of zirconia ceramic materials in industry and life.

Typical applications for zirconia ceramics: tools, dentures, bearings, etc.
Typical applications

Battery material

Solid oxide fuel cells (SOFC) are a new type of green energy that developed rapidly in the 1980s. Due to its high energy conversion efficiency (up to 65%) and the use of various fuels such as hydrogen, carbon monoxide, methane, etc., the system design is simple, and the pollution-free emission is low, which will be applied to the power generation system. The solid electrolyte is the core component of SOFC.

Schematic diagram of a solid fuel cell
Schematic diagram of a solid fuel cell

Zirconium oxide ceramics have become the most researched and widely used solid electrolyte materials because of their high ionic conductivity, good chemical stability, and structural stability.

Refractory

Zirconium oxide is an excellent special oxide refractory material and used at a high temperature (2300 ℃ – 2400 ℃). It has good chemical stability and is not easy to decompose, and is highly corrosive and resistant to acid and alkali slag. The industry uses zirconia-based refractories to produce refractory materials with excellent thermal shock resistance, corrosion resistance and wears resistance, which can make refractories have better performance and longer service life. It has been applied to the manufacturing process of industrial continuous casting steel and alloy materials and has important significance for improving the quality and cost of metal materials such as steel.

Zirconia foam ceramics for steel water filtration
Zirconia foam ceramics for steel water filtration

Optical material

Zirconium dioxide ZrO2 is a high refractive index, low absorptive material that can be used in coatings in the near-ultraviolet (<300 nm) to infrared (~8 μm) spectral regions. Nano-zirconia is added to the special coating material to increase the refractive index of the coating without changing the light transmittance. In the field of optical materials, in addition to being used as a coating, nano zirconia can also be used as a polishing material for optical lenses.

Electronic materials

For engines that use three-way catalytic converters to reduce pollution emissions, oxygen sensors are essential in the automotive industry. It uses the ceramic sensitive component to measure the oxygen potential in the exhaust pipe of the automobile, and calculates the corresponding oxygen concentration by the principle of chemical balance, and achieves the measuring component that monitors and controls the combustion air-fuel ratio to ensure the product quality and the exhaust gas emission standard. There are two types of oxygen sensors currently in use: titanium oxide and zirconium oxide. The core component is a porous zirconia ceramic tube, which is a solid electrolyte with sintered porous platinum (Pt) electrodes on both sides.

Plumbum zirconate titanate (PbZrxTi1-xO3, PZT) ceramics are a commercially important class of piezoelectric materials. Compared with other piezoelectric ceramics, PZT ceramics not only have high Curie temperature and piezoelectric coefficient, but also are easy to be doped and modified, and have good stability, so they have an important position in the electronic machinery manufacturing industry. They are the basic material for the preparation of most electromechanical devices such as sonar, hydrophone, ultrasonic generator, volt generator, and position trimmer.

Brake material

Ceramic materials have high heat resistance, thermal stability, and hardness. As an important member of advanced ceramics, zirconia ceramics certainly have similar characteristics. In view of the excellent quality of advanced ceramics, researchers have introduced it into friction materials to obtain longer-lasting and more durable friction materials under the most extreme working conditions. Today, more and more composite formulations for brake pads and clutch linings contain ceramic materials.

Many ceramic materials can be added to the brake material, including the zirconia ceramics we introduce today, in addition to silicon carbide, alumina, silica, and magnesia

Example of the microstructure of the brake pad material
Example of the microstructure of the brake pad material

Thermal spray material

Using thermal spraying technology, the ceramic coating is deposited on the metal collective, and the characteristics of high-temperature resistance, heat insulation, wear resistance, corrosion resistance and insulation of the ceramic are combined with the toughness, workability, the electrical and thermal conductivity of the metal material. The ideal composite coating product has become an important development direction in the field of composite materials and product development.

Aviation surface protection technology is a hotspot of thermal spraying for many years. The key components of aero-engines are high-temperature alloy turbine blades and turbine disks. The current engine turbine inlet temperature is close to or exceeds the melting point of the alloy, and such high temperatures will affect the function of the engine and dye. Therefore, an important development trend of superalloys is to coat the surface of the alloy with a high-melting ceramic coating (Thermal Barrier Coatings – TBCS) with good thermal insulation properties. At present, the most widely used TBCS is yttria-stabilized zirconia materials.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit http://www.samaterials.com for more information.

What Are the Uses of Advanced Composite Ceramic Substrates in Missiles?

In the mid-1980s, the United States developed an aerospace aircraft program that required both high-temperature tolerance and light mass. For this purpose, a variety of new high-temperature materials were developed, including advanced resin matrix composites, metal matrix composites, ceramic matrix composites, and carbon/carbon composites. Ceramic material is the preferred material for missile radome because of its excellent mechanical, thermal and electrical properties. The radome is the most widely used ceramic matrix composite material in missile structure.

Missile radome

The missile radome is located at the front end of the missile. Its function is to protect the navigation antenna from damage so that the missile can effectively hit the target. It is not only an important part of the aerodynamic shape of the missile but also the protection device of the antenna. During the flight of the missile, the radome should not only withstand aerodynamic heating and mechanical overload, resist the erosion of rain, sand, and other adverse working conditions, but also meet the stringent requirements of electrical performance proposed by the missile control loop. Therefore, the missile radome material should have the following properties:

Missile-radome

  • Excellent dielectric properties

In the guidance system, the transmission efficiency and aiming error of the radome are very sensitive to the dielectric properties of the material and its relationship with temperature and frequency. It is required that the material has low dielectric constant (10) and dielectric loss, and the dielectric properties do not change obviously with temperature and frequency.

  • Good heat resistance and thermal shock resistance

The high Mach number of missile can make the radome of instantaneous heating rate is as high as above 120 ℃ / s, so the material is required to have good thermal shock resistance, and the molecular structure of the material is required to be stable when the temperature is raised, and the material properties (such as dielectric properties and mechanical properties) change little to ensure that the radome can work normally when the temperature is raised.

  • High strength structural properties

The strength of the radome material should be high and rigid enough to satisfy the mechanical stress and bending moment caused by the longitudinal or transverse acceleration of the aerodynamic forces in the spacetime of the missile flying at high speed.

  • Resistance to rain erosion

It plays a decisive role in the design allowable range of impact Angle and the sensitivity of aircraft in rain erosion.

  • Low-temperature sensitivity

The dielectric properties and strength properties of general materials change obviously when they work at high temperature. Therefore, the properties of the radome material, especially the dielectric properties and strength, are affected by the temperature change as little as possible.

Ceramic-based missile radome

Ceramic-based missile radome materials mainly include silicon nitride based, a silicon oxide based and phosphate-based materials. Silicon nitride ceramics have not only excellent mechanical properties and high thermal stability but also low dielectric constant. Its decomposition temperature is 1900 ℃, and its erosion resistance is better than fused silica, and it can withstand 6 ~ 7 Ma rating of flight conditions. Silicon nitride ceramic composite radome is one of the main research targets in various countries, which has been identified as the most promising radome material by the test of the Georgia Institute of Technology. Yttria Stabilized Zirconia (YTZ), also known as yttria-zirconia, is the strongest ceramic material. This material offers the highest flexural strength of all zirconia-based materials, and the research on zirconia-based materials as missile radome is in progress.

Ceramic-based-missile-radome

  • Silica-based material

Because of the high flying Mach number of the missile and the relatively long heating time, if the radome of the medium-range missile is made of a single quartz ceramic material, it cannot meet the bearing requirement of thermal stress. In order to meet the requirements of medium and long-range ground-to-ground tactical and strategic missile radome, quartz glass, high-silica puncture fabric and orthogonal tri-directional quartz fabric reinforced silica matrix composites have been developed and successfully applied.

  • Phosphate-based materials

Phosphate matrix composite material is a kind of Russian characteristic permeable material, which is made by impregnating cloth or fabric with a phosphate solution and then curing under pressure. Aluminum phosphate has stable performance in 1500 ~ 1800 ℃. At present, such materials have been used in cruise missiles, anti-missile missiles, tactical missiles and space shuttles. The most obvious disadvantage of phosphate is that it is highly hygroscopic, so the surface of the composite material needs to be coated with an organic coating for moisture-proof treatment.

  • Silicon carbide ceramic matrix composites

Silicon carbide ceramic matrix composites have a series of excellent properties, such as low density, high-temperature resistance, ablation resistance, erosion resistance, and oxidation resistance, and it has a wide application prospect in the field of aerospace. Since the late 1980s, the United States has successfully developed a series of C/SiC, SiC/SiC ceramic matrix composites, which can be applied to the re-entry nose cone of missiles, the front end of wings and other heat-resistant structures.

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Why Is There a Soaring Market Growth for Nanocomposite Zirconia?

Zirconium dioxide (ZrO2) is a kind of metal oxide materials with many excellent properties such as high melting point (2700 ℃) and high boiling point, small coefficient of thermal conductivity, thermal expansion coefficient, high-temperature resistance, good wear resistance, corrosion resistance. Nano zirconia powders have many important applications because of their nanometer properties. Fine ceramics made of nano zirconia have some special properties under different conditions, such as insulator at room temperature, conductivity, sensitivity, and toughness at high temperature.

In the zirconium industry chain, the most widely used composite zirconia is the stable/partially stable zirconia formed by doping the corresponding rare earth elements according to different uses. The variety and content of the added rare earth elements can be adjusted to produce composite zirconia that meets the requirements of different uses, such as yttrium stabilized zirconia used as structural parts and zirconium and cerium eutectic used as catalysts. Compared with common zirconia, nano-scale composite zirconia has a smaller particle size and reaches the nanometer level. Its higher additional use value and the market scale of over ten billion is being rapidly developed.

Here are 10 applications of nanocomposite zirconia.

Nano-Composite-Zirconia

Denture material

Nano ZrO2 can obviously improve the room temperature strength and stress strength factor of ceramics, thus doubling the toughness of ceramics. The composite bioceramics prepared with nanometer ZrO2 has good mechanical properties, chemical stability, and biocompatibility. It is a promising composite bioceramics material, especially in the field of dental materials and artificial joints. Biomaterials refer to materials with natural organ tissue function or partial function, and they are the latest branch of biomedical science and have broad application prospects. Bioceramics have been widely used in the field of oral prosthodontics because of its excellent biocompatibility, stability, and aesthetics.

Zirconia toughened ceramic, as a new fine ceramic, has good mechanical properties (fracture toughness, strength, hardness, etc.), biocompatibility and stability, aesthetics, thermal conductivity and formability, which can well solve the problem of insufficient strength and toughness of conventional all-ceramic crown materials. Secondly, as an excellent bioinert ceramic, it has excellent chemical stability both as an oral prosthesis and an implant, which fully meets the standard as an oral prosthesis material.

Joint prosthesis

The initial ceramic artificial joint is not perfect and has undergone four generations of process improvement so far, gradually becoming perfect. The fourth generation of the artificial ceramic joint is composed of several kinds of oxidized crystal materials such as zirconia, with good toughness and strength its performance is much better than that of the third generation of the ceramic joint. When zirconia is compounded, the crystal particles become smaller. More importantly, zirconia disperses and absorbs the energy of the fracture, inhibiting crack growth. Zirconia is the best prosthesis material currently used in clinical hip replacement, the ceramic material with the best wear resistance is the most ideal especially for middle-aged and young patients with high exercise.

Joint-prosthesis
Joint-prosthesis

Oxygen sensor

The sensor made of zirconia has good electrical conductivity, which plays an important role in controlling automobile exhaust and boiler combustion in power plant. In the automotive industry, oxygen sensors are essential for the use of three-way catalytic converters in engines to reduce emissions and pollution. Zirconia oxygen sensor is one of the most mature oxygen sensors with the largest output. It is one of the key components in automobile emission control system, and its signal output characteristics directly affect the engine fuel economy and emission control.

The catalyst for automobile exhaust purification

The catalyst for automobile exhaust purification: carrier (alumina), co-catalyst (nano-coating to increase the specific surface area, as a hydrogen storage material), catalyst (general gasoline parking space platinum, palladium, rhodium, etc., diesel vehicles for vanadium, tungsten, titanium, etc.). Zirconium-cerium solid solution composite oxide is used as cocatalyst and important coating material. In addition, zirconium-cerium solid solution is also widely used in sensor materials, polishing materials, fuel cells, structural materials, high strength ceramics, and other fields.

Catalysts for chemical synthesis of aromatic hydrocarbons

Zirconia has long been used in the study of isomeric synthesis. Isomeric synthesis is a process in which syngas is converted into isobutene and isobutane (i-C4) in high selectivity, and it is mainly composed of metal oxides such as zirconia, thorium oxide and cerium oxide. Since Pichler et al. studied isomeric synthesis for the first time, zirconia has become the core of isomeric synthesis catalysis research due to its high i-C4 selectivity and non-radioactivity. This highly selective formation of i-C4 has been attributed to the fact that zirconia surfaces are both acidic, alkaline, oxidizing and reductive. If a single zirconia catalyst can convert syngas into aromatics or high-octane products in one step, the problem of mismatching of active centers in the catalytic system doped by metal and molecular sieve can be avoided, which has far-reaching significance for future energy development.

Ceramic core for fiber optic connector

Due to the excellent mechanical properties, chemical stability and extremely high precision of nano-yttrium oxide stabilize zirconia (nano-YSZ) powders, it can be used to prepare rare earth structure ceramic fiber core (precision needle) and sleeve for optical fiber connectors. It is the optical fiber passive device with the widest application range and the largest demand in the optical fiber network and an important part of the information network infrastructure construction.

zirconia-ceramic-cores-for-fiber-optic-connectors
zirconia-ceramic-cores-for-fiber-optic-connectors

Mobile terminal products

As 5G, wireless charging and other new transmission methods approach, wireless frequency band becomes more and more complex, and metal case shielding will become a major bottleneck. The strict layout of 5G antenna requires the transformation of the existing metal housing material, and both ceramic and glass will be optional. Metal is also unfriendly to wireless charging. Most of the previous wireless charging technologies used electromagnetic wave raw materials, and metal would cause interference to the electromagnetic wave, which greatly reduced the charging efficiency. There are alternative materials such as plastics, glass, and ceramics. Plastic surfaces are prone to scratches, while glass is brittle, so ceramic materials, with their excellent physical properties, are gradually penetrating the appearance of smartphones.

The mi MIX is equipped with an all-ceramic body, and the microcrystalline zirconium ceramics, second only to sapphire hardness, is selected as the blank. It has a Mohs hardness of 8.5. Keys, knives and so on do not cause any wear and tear.

Fingerprint-identification
Fingerprint identification

In fingerprint unlock applications, zirconia’s dielectric constant is three times that of sapphire, making the signal more sensitive. Compared with the 0.3mm sapphire cover plate used in iPhone Touch ID, the zirconia has higher recognition when the same thickness is used. It is expected that the fingerprint recognition will become the standard of smartphones in the next 5-10 years.

Zirconia ceramic crucible

In the smelting of rare and refractory precious metals and alloys, the general materials are difficult to meet the requirements due to the need to heat to a higher temperature. Crucible made of zirconium oxide can be heated to 2430 ℃, the zirconium oxide thus become the first choice under the condition of high-temperature crucible pot zirconia materials.

Zirconia ceramic cutter

Ceramic cutters were used in the early 20th century, but their brittleness limited their range of use. However, its toughness has been greatly improved with the development of nanocomposite zirconia composite in recent years. Zirconia can be processed into various cutting tools, while the zirconia ceramic blades are made of special ceramic materials belonging to non-metallic materials. Zirconia ceramic tool not only has the advantages of traditional metal tools but also has the characteristics of no rust, health, wear resistance and so on, so it is known as ceramic steel.

Refractory material

Zirconia is often used as refractory due to its high melting point, low thermal conductivity, and stable chemical properties. The advantages of refractory materials prepared with nano zirconia are more obvious, such as high-temperature resistance, high strength, good thermal insulation performance, and excellent chemical stability.

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