Zirconium oxide is a kind of high temperature resistance, corrosion resistance, wear resistance and good electrical conductivity of inorganic non-metallic materials, that should be used for refractory material field in the early 1920 s, until the mid – 1970 – s, Europe and the United States, the advanced countries in the world have had the same person research and development of zirconium oxide production technology and zirconium oxide series products production, further to expand application field of zirconium oxide to structural materials and functional materials, zirconium oxide at the same time also is in the national industrial policy to encourage is one of the focus on the development of high-performance new materials, is widely used in various industries.
Basic properties of zirconia 1
There are three crystal types of pure zirconia under normal pressure, the low temperature is monocline crystal system, the density is 5.65g/cm3, the high temperature is tetrahedral crystal system, the density is 6.10g/cm3, the higher temperature is cubic crystal system, the density is 6.27g/cm\ the relationship between them is as follows:
1170, 2370, 2715 c
Monoclinic Zr02 — quadrate Zr02 — cubic Zr02 — melt
Natural Zr 2 and Zr 2 obtained by chemical method belong to monoclinic crystal system. The transformation between monoclinic and tetragonal forms was associated with a volume change of about 7%. When heated, the monoclinic Zr02 turns into a tetragonal Zr02, with volume contraction; when cooled, the monoclinic Zr02 turns into a tetragonal Zr02, with volume expansion. But this kind of expansion and shrinkage does not occur at the same temperature, the former is about 1200 ℃, which is about 1000 ℃.
Volume change because the changing of the crystal shape, can cause cracking, so pure zirconia ceramics are difficult to produce, through the practice found that adding suitable amount of the crystal type of stabilizers, CaO, MgO style. Y203, Ce and other rare earth oxides such as 2, can reduce Zr02 phase change temperature below room temperature, the high temperature stability of the square and cubic zirconia at room temperature can also exist in stable or metastable form, no abnormal expansion and contraction of cubic and square crystal type of stabilized zirconia (FSZ) and partially stabilized zirconia (PSZ).
Zirconium oxide as the amount of stabilizer and people in different, can produce different crystal forms of zirconium oxide, in the process of phase change due to the change of the size and shape, can absorb energy, reduce the crack tip stress concentration, to prevent crack extension, improve the toughness of ceramic material, from the study and application of zirconium oxide phase transformation toughening ceramics has been the rapid development, there are three main types: partially stabilized zirconia ceramic, sifang polycrystal zirconia ceramic, zirconia toughening ceramics.
Applications of zirconia
2.1 zirconia refractory
Zirconia has been used in the field of refractories since the early 1920s and still has a place in the field of refractories today.
2.2 zirconia structural ceramics
In 1975, r.g. g. vie of Australia prepared partially stabilized zirconia with calcium oxide as the stabilizer. For the first time, the toughening effect of zirconia martensite phase transformation was used to improve the toughness and strength, greatly expanding the application of zirconia in the field of structural ceramics.
2.3 functional zirconia ceramics
2.3.1 zirconia ceramic ball for ballpoint pen
Is pen giants in our country, there are four in every five pen on international from China, market has formed nearly 80 billion yuan/year, under normal circumstances, the ballpoint pen with ball beads are mainly stainless steel and tungsten carbide material, but this kind of ball bead often appear in the broken wires in the writing, drop beads, beads, death dip in the first class phenomenon, at present by the hebei province yong kalumpang dah sing material co., LTD., with tsinghua university state key laboratory of new ceramics and process developed “ball pen with zirconia ceramic ball” to overcome the above defects, filled the domestic blank, The scientific and technological achievements have been listed as the national pen industry “eleventh five-year” national key promotion of new products.
2.3.2 zirconia ceramic cutter
Zirconia ceramic cutting tools with high strength, wear resistance, no oxidation, no rust, acid and alkali resistant, antistatic, won’t react with food, the characteristics of blade glossy jade at the same time, is the world’s ideal high-tech green cutting tools, the market at present main products are: zirconia ceramic knife, scissors, razor, knife, etc., in recent years in places such as Europe, America, Japan and South Korea have begun to pop.
2.3.3 zirconia high-temperature heating material
Zirconia at room temperature for insulating materials, resistivity is as high as 1015 Ω NaN, are conductive temperature to 600 ℃, and in more than 1000 c is a good conductor, can make 1800 c high temperature heating elements, the highest working temperature can reach 2400 c, the current has been successfully applied to 2000 c for the heating element and its equipment under oxidizing atmosphere, MHD power generation electric pole material also in the positive research.
2.4 zirconia decorative materials
Decorative ceramics in the traditional sense are made of ordinary silicate system materials, such as vases in display porcelain, ceramic drawing boards, ceramic wall tiles for indoor and outdoor decoration, etc. Zirconia decorative materials have opened up a new field for human to beautify themselves. At present, they are mainly used in simple accessories and accessories with both application functions.
2.4.1 zirconia gem materials
Zirconia gem materials are divided into natural cubic zirconia and synthetic cubic zirconia.
In the natural state, it is extremely difficult to find natural cubic zirconia, which determines that it has the characteristics of gem material rarity. Naturally formed cubic zirconia is very rich in color, and the price of large high-quality natural zirconia is not lower than that of diamond, which is a very rare precious natural gem.
Cubic zirconia is a cheap and beautiful alternative to diamonds.
2.4.2 zirconia ceramic jewelry
Zirconia ceramic jewelry mainly has the following several types: (1) embedded in the zirconia the silver jewelry, here zirconia scope is broad, including zircon dioxide, industrial zirconium dioxide, stable high purity zirconium dioxide, zirconium dioxide, ultrafine zirconium dioxide, zircon sand, zircon powder, etc., has made the zirconia silver rhodium plated jewelry is very popular with European customers. (2) pure zirconia materials accessories products, is currently the decorative ceramic quietly and the type of product, the market is the domestic existing ceramic production company in research, development and sales of such products in the process of walking in the forefront of the industry, the government also gave the attaches great importance to the industry, in 2006, the Beijing municipal science and technology sme technology innovation fund free sponsorship program is the development of color zirconia structural ceramics, there are nearly 300 kinds of new ceramic accessories products, including both new design also includes a variety of colour and lustre is bright color, Moreover, this kind of product has a good market in Europe, America, Japan, Hong Kong and other regions of China, especially favored by the European market. (3) have the application of functional accessories, typical products are ceramic watch case, watch ring, watchband and other products, international famous brand Chanel/ Chanel, RADO/ RADO watches are all ceramic style, and the price is not cheap.
2.5 other applications of zirconia
2.5.1 forming a composite phase material with zirconia
Composite phase materials formed with other materials, such as zirconia and alumina, mullite and other materials formed by the composite phase materials, got a better performance than the single phase materials of new materials.
2.5.2 common ceramic additives
Ceramic glaze materials: application of zirconia as yellow-green pigments good color aid, to obtain good performance vanadium zirconium yellow pigment, must choose qualitative pure zirconia, in addition, in the glaze manufacturing pure zirconium oxide can improve the high temperature viscosity of glaze and enlarge the temperature range of high temperature viscosity change, has good thermal stability, its content is 2% ~ 3%, can improve the cracking resistance of glaze, also because of zirconium oxide chemical inertness, can improve the stability of glaze is changed to learn and the ability of resistance to acid and alkali erosion, is sometimes used to make opacified glaze.
Development prospect of zirconia
With the development of modern science and technology and testing technology, and human understanding of zirconium oxide will further deep, zirconium oxide will be new guise, in recent years, domestic companies have been able to produce high-quality ultrafine zirconia powder, and most products export, but in terms of powder preparation is still in a relatively backward level, the future development should develop in the direction of ultra fine, high purity, product manufacturing should be toward the new function, new application field direction, zirconium oxide has been expanding its application field.
According to the above findings, the application field of zirconia ceramic materials is gradually developing into the field of decorative ceramics, jewelry and jewelry, and high-end luxury consumption, along with the trend of diversified types and functions