What Are the Nano Zirconia Composite Ceramic Powders?

Zirconia is a new structural ceramic material developed in the 1970s. It is widely used in metallurgy, electronics, chemical industry, machinery and other fields due to its abrasion resistance, corrosion resistance, high strength, and high melting point.

Zirconia ceramic material, as the most important material in advanced ceramics, is an important basic material for the development of modern high-tech industry. In particular, nano-oxide ceramics with its special structure and performance has become the focus of the industry. The following is a brief introduction of the powder materials needed to prepare nano zirconia ceramics.

Ni-P coated nano zirconia composite powders

The preparation process of Ni-P coated nano zirconia (ZrO2) composite powders is firstly to prepare nano-ZrO2 powders by the chemical precipitation method, and then to prepare Ni-P nano-ZrO2 powders by an electroless plating method. Since ZrO2 has no autocatalytic activity in the electroless nickel plating solution, it is necessary to pretreat ZrO2 nanoparticles. Generally, Pd2+ is directly adsorbed on the surface of ZrO2 powder by one-step palladium catalysis method, and then Pd2+ is reduced to palladium in reducing solution so that the surface of nanopowder has the catalytic activity of electroless nickel plating. The two-step sensitization-activation method is usually used in the pretreatment of non – conductive powders. However, it is difficult to remove the residual nickel ions in the powder after two-step treatment, which often brings adverse effects on the activity of the powder. At present, one-step palladium catalysis and in-situ palladium pretreatment are used.

At present, Ni-P coated nano zirconia composite powders have been widely used and studied in semiconductor nanomaterials.

SEM images of Ni-P coated nano zirconia composite powders
SEM images of Ni-P coated nano zirconia composite powders

Zirconia toughened alumina ceramic composite powder

Zirconia toughened alumina ceramic is one of the most widely studied structural ceramic materials. The toughening mechanism of zirconia toughening alumina ceramics is the refinement of matrix grain, the toughening of phase change, the toughening of microcrack, the turning and bifurcation of crack. The properties of zirconia toughened alumina ceramics are mainly determined by the microstructure formed during sintering, and the microstructure is mainly determined by the powder state of raw materials. Therefore, the preparation of high-quality Al2O3/ZrO2 nanocomposite ceramic powders is the prerequisite for the preparation of zirconia toughened alumina ceramics with excellent properties. The preparation methods of Al2O3/ZrO2 nanocomposite ceramic powders mainly include mechanical mixing method, multi-phase suspension mixing method, the sol-gel method, chemical precipitation method, etc.

Alumina is a kind of high-strength matrix in the composite ceramic system of zirconia toughening alumina, and the zirconia in the intercalation provides a phase change toughening mechanism. The use of ZrO2 phase change properties to toughen ceramic materials is still one of the main research topics of ceramic toughening in the future.

Zirconia toughened alumina composite ceramics have excellent corrosion resistance, thermal shock resistance, high strength, and toughness, as well as wide application prospects. Zirconia toughened alumina composite ceramics can be used to make ceramic cutters for the processing of cast iron and alloy, and the interface structure of engineering ceramics can be made to extend the service life of engineering materials. Alumina toughened with zirconia can be used to make wear-resistant ceramic balls. Due to its good biocompatibility, alumina can also be used as a biomedical material for the reconstruction and repair of hard tissues (teeth).

Boron nitride-zirconia composite powder

Boron nitride-zirconia composite powders were prepared by mechanical mixing method. Boron nitride, zirconia, and additives were used as the main raw materials. After mixing, the powders were ball-ground and mixed in an alcohol medium, and then the zirconia composite ceramics were sintered in a hot press sintering furnace. Due to the poor sintering capacity of pure boron nitride and its difficulty in sintering densification, CaO, B2O3, Al2O3, and ZnO are generally added as sintering AIDS.

Boron nitride-zirconia composite ceramics are characterized by high strength, high toughness, high thermal conductivity, low expansion, and excellent physical and chemical properties, such as chemical inertness and chemical corrosion, which are present in molten metals. In addition, it also has excellent thermal shock resistance, erosion resistance, wear resistance and easy processing and other properties, which make the material suitable for thin strip continuous casting side seal plate, jet forming liquid guide pipe, the nozzle for metal spinneret, continuous casting functional refractories and other fields.

Boron nitride - zirconia composite powder
Boron nitride-zirconia composite powder

Nano cerium-zirconium composite oxide powder

The preparation methods of nano cerium-zirconium composite oxide powders include high-temperature roasting, the sol-gel method, coprecipitation method, hydrothermal method, and solid phase reaction method. High-temperature roasting was carried out in a water-ethanol solvent, and the suspension consisting of dry Al (NO3) 3•9H2 O•Ce (NO3) 3•6H2O and monocline phase zirconia nano-powder was pyrolyzed by high-temperature, Al2O3 doped CeO2 coated monoclinal zirconia powders with a particle size less than 100 m were prepared.

Nano cerium - zirconium composite oxide powder
Nano cerium-zirconium composite oxide powder

Nano cerium-zirconium composite oxide materials are used as auxiliary catalysts, mainly used in automobile exhaust treatment, with good high-temperature stability, high REDOX ability, high oxygen storage, and release capacity.

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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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