Basic properties and development of zirconia ceramics

Basic performance of zirconia ceramics , is gradually being adopted by decorative ceramics, such as colored zirconia ceramics, ceramic jewelry, etc.

Zirconia ceramics is an inorganic non-metallic material with high temperature resistance, corrosion resistance, wear resistance and excellent electrical conductivity. It was used in the field of refractory materials in the early 1920s until the mid-1970s. Japan’s advanced countries have invested in the research and development of zirconia ceramic production technology and the production of zirconia ceramic series products, and further expanded the application field of zirconia ceramics to structural materials and functional materials. At the same time, zirconia ceramics are also encouraged by the national industrial policy. One of the high-performance new materials, is currently widely used in various industries.

Basic properties of zirconia ceramics There are three crystal forms of pure zirconia under normal pressure, monoclinic at low temperature with a density of 5.65g/cm3, tetragonal at high temperature with a density of 6.10g/cm3, and cubic at higher temperatures , the density is 6.27g/cm3, and the transformation relationship between them is as follows: tetragonal and cubic zirconia ceramics can also exist in stable or metastable forms at room temperature, forming stable zirconia ceramics with cubic and tetragonal crystal forms without abnormal expansion and contraction (FSZ) and partially stabilized zirconia (PSZ). With the different amount of stabilizer added in zirconia ceramics, zirconia ceramics with different crystal forms will be produced. Due to the change of volume and shape during the phase transformation process, it can absorb energy, reduce stress concentration at the crack tip, prevent crack propagation, and improve ceramics. The toughness of the material, since then, the research and application of zirconia phase transformation toughened ceramics have been rapidly developed. There are mainly three types: partially stabilized zirconia ceramics; tetragonal zirconia polycrystalline ceramics; zirconia toughened ceramics.

Pure zirconia ceramic is white, yellow or gray when it contains impurities, generally contains HfO2, and is not easy to separate. The world’s proven zirconium resources are about 19 million tons, and zirconia ceramics are usually obtained by purifying zirconium ore. There are three crystal states of pure ZrO2 under normal pressure: monoclinic (Monoclinic) zirconia (m-ZrO2), tetragonal (Tetragonal) zirconia (t-ZrO2) and cubic (Cubic) zirconia (c-ZrO2). Three crystal forms exist in different temperature ranges and can be interconverted:

Temperature Density

• Monoclinic zirconia (m-ZrO2) <950℃ 5.65g/cc
• Tetragonal zirconia (t-ZrO2) 1200-2370℃ 6.10g/cc
• Cubic Zirconia (c-ZrO2) >2370℃ 6.27g/cc

The above three crystal states of zirconia ceramics have different physical and chemical properties. In practical applications, in order to obtain the required crystal form and performance, different types of stabilizers are usually added to make different types of zirconia ceramics, such as partially stabilized zirconia (partially stabilized zirconia). Stabilized zirconia, PSZ), when the stabilizer is CaO, MgO, Y2O3, respectively expressed as Ca-PSZ, Mg-PSZ, Y-PSZ, etc. The tetragonal zirconia composed of metastable t-ZrO2 is called tetragonal zirconia polycrystal (TZP). When the added stabilizers are Y2O3 and CeO2, they are expressed as Y-TZP, Ce-TZP, etc. respectively.

The development prospect of zirconia ceramics

With the development of modern science and technology and testing technology, human’s understanding of zirconia ceramics will be further deepened, and zirconia ceramics will appear with a new look. In recent years, some china companies have been able to produce high-quality ultra-fine oxide ceramics. Zirconium ceramic powder, and most of the products are exported, but the powder preparation is still at a relatively backward level. The future development should be in the direction of ultra-fine and high-purity, and product manufacturing should be directed towards new functions and new applications. Direction development, and constantly expand the application field of zirconia ceramics. At present, the application field of zirconia ceramic materials is gradually developing into the field of decorative ceramics, jewelry, and high-end luxury consumption, which is developing along the trend of diversification of types and functions.