Properties of zirconia ceramics

Properties of zirconia ceramics
Zirconia ceramic (ZrO2) has high melting point, high hardness, excellent wear resistance, and is an insulator at room temperature, while it has conductivity at high temperatures. Pure ZrO2 is white, yellow or gray when containing impurities, and generally contains HfO2, making it difficult to separate. Zirconium oxide is usually obtained by purifying zirconium ore.
There are three crystal forms of zirconia: low-temperature monoclinic (m-ZrO2), moderate temperature tetragonal (t-ZrO2), and high-temperature cubic (c-ZrO2). These three crystal forms exist in different temperature ranges and can be transformed into each other.
Zirconia ceramic is a new type of high-tech ceramic, which not only has high strength, hardness, high temperature resistance, acid and alkali corrosion resistance, and high chemical stability, but also has characteristics such as scratch resistance, wear resistance, no signal shielding, and excellent heat dissipation performance. At the same time, it has strong machinability, good appearance effect, and is suitable for mass production.
1. High melting point
The melting point of zirconia is 2715 ℃, and its high melting point and chemical inertness make it a good refractory material.
2. High hardness and good wear resistance
Zirconia ceramics have high hardness and good wear resistance. From the specific data, the Mohs scale hardness of zirconia ceramics is about 8.5, very close to the Mohs scale hardness of sapphire 9.
3. Relatively high strength and toughness
Zirconia ceramics have high strength (up to 1500MPa).
4. Low thermal conductivity, low coefficient of expansion
The thermal conductivity of zirconia is the lowest among common ceramic materials (1.6-2.03W/(m.k)), and its thermal expansion coefficient is close to that of metals. Therefore, zirconia ceramics are suitable as structural ceramic materials.
5. Good electrical performance
The dielectric constant of zirconia is three times that of sapphire, making it more sensitive and suitable for fingerprint recognition patches. From the perspective of shielding effectiveness, zirconia ceramics, as a non-metallic material, have no shielding effect on electromagnetic signals and will not affect the internal antenna layout at all. They can be conveniently integrated and formed to adapt to the 5G era.