Zirconia has been used in the field of refractories since the early 1920s, and it still has a place in the field of refractories.
The melting point of zirconia is as high as 2700 C. Even if it is heated to more than 1900 C, it will not react with molten metals such as aluminum, iron, nickel, platinum, silicate and acid slag. Therefore, the crucible made of zirconia material can successfully melt platinum, palladium, ruthenium, cesium and other precious metals and their alloys, and can also be used to melt potassium, sodium, quartz glass, oxides and salts.
Zirconia refractory fibre
Zirconia fiber is the only kind of ceramic fiber refractory that can be used for a long time in the ultra-high temperature environment above 1600 C. It has higher service temperature and better heat insulation performance than alumina fiber, mullite fiber, aluminum silicate fiber and so on. Moreover, it has stable chemical properties at high temperature, corrosion resistance, oxidation resistance, and non-volatile.
Zirconia kiln materials
As a refractory, zirconia is mainly used in the key parts of large glass tank kiln. The content of zirconia is only 33%~35% in the early use of zirconia refractory. In Japan, the zirconia refractory containing 94%~95% zirconia has been successfully developed. It is used in the top and key parts of the glass tank kiln, greatly improving the life of the glass furnace.
Zirconia hollow spheres of different sizes were obtained by melting and blowing zirconia to prepare various high-grade insulating bricks, which avoided the dust pollution problem after ceramic fiber aging.
Zirconia structural ceramics
In 1975, R.G. Garvie, Australia, prepared partially stabilized zirconia with calcium oxide as the stabilizer. For the first time, the effect of martensitic transformation toughening of zirconia was utilized to improve the toughness and strength, which greatly expanded the application of zirconia in structural ceramics.
ZrO2 toughened ceramics are in fact partially stabilized ZrO2 with different stabilizers. The crystal structure of ZrO2 toughened ceramics is a polycrystalline structure with cubic and monoclinic phases as the main body of the tetragonal phase. It has the characteristics of high toughness, high bending strength, high hardness and wear resistance, and shows its application and universality. It has a wide range of applications in machinery, electronics, petroleum, chemical, aerospace, textile, precision measuring instruments, precision machine tools, biological engineering and medical devices and other industries.
Because of its low thermal conductivity, good strength and toughness, low modulus of elasticity, high thermal shock resistance and high working temperature, partially yttria stabilized zirconia are used to manufacture Diesel engine parts and internal combustion engine parts. It has small volume, lightweight, and high thermal efficiency. It is an effective energy-saving engine. The application of ZrO2 toughened ceramics in internal combustion engines is successful. The goal of the US adiabatic engine program is to cancel the water cooling system, insulate the combustion chamber, utilizing the heat discharged, improve thermal efficiency and reduce engine weight. In adiabatic internal combustion engines, tough zirconia can also be used as cylinder liner, piston head, valve guide, intake and exhaust valve seat, bearing, tappet, cam, cam follower and `piston ring' and other parts. The thermal efficiency of ceramic adiabatic internal combustion engine has reached 48%. Ceramic adiabatic internal combustion engine eliminates 360 parts such as radiators, pumps, cooling pipes, and reduces mass by 191. Toughened ceramics are used as rotors in rotary cylinder engines. Japan, the United States, Germany, and other developed countries use ductile zirconia to make engines. It also manufactures computer driven components, seals, cooling blades for aero engines, etc.
Partially stabilized zirconia has high hardness and wear resistance, so zirconia has a wide range of applications in the field of grinding media and abrasive tools: such as ball mill and ball mill lining and wear-resistant parts, drawing dies and so on. China has more than half of the toughness ceramics in grinding media, and zirconia ball is the absolute advantage.
Because zirconia has no magnetism, no conductivity, no rust, wear resistance, so it is widely used in the field of biomedical instruments and cutting tools. For example, it is used in medical scalpels and cutting tapes and other products with magnetic materials, making artificial bones, artificial joints, artificial teeth and so on. Recently, partially stabilized ZrO2 has been fabricated by powder metallurgy for magnetic shielding watches, corrosion resistant watches, and other instrumentation components. It is used to make choppers, scissors, screwdrivers, hammers, saws, axes, etc. It is more suitable for eating raw food and cooked food. Ceramic tools toughened with high cerium zirconia have recently been developed in Japan. Ce2O3 is used as the stabilizer in the composite to replace cermet. The fracture toughness is three times that of metal and the cutting ability is increased by 1.5 times.
As a new application area of zirconia, structural ceramics have attracted more and more attention. They are mainly optical fiber connectors and bushing, zirconia grinding media, cutting tools, textile and tobacco machinery bearing plates, etc.
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