The Function and Properties of Zirconia Ceramics

The role of zirconia ceramic materials:

Zirconia ceramic materials have excellent physical and chemical properties such as high hardness, high strength, high toughness, extremely high wear resistance, and chemical corrosion resistance. It has been widely used in refractory, machinery, electronics, optics, aerospace, biology, chemistry and other fields.

Performance of zirconia ceramic materials:

Zirconia ceramic materials have excellent properties such as high melting and boiling points, high hardness, insulation at room temperature, and conductivity at high temperatures. Zirconia ceramic materials have three crystal forms and belong to the polycrystalline phase transformation material. The stable low-temperature phase is a monoclinic phase; Above 1000 °, the tetragonal phase gradually forms; Above 2370 ° C, it transforms into a cubic crystalline phase.

Zirconia ceramics have a melting point of 2700 ℃ and a Mohs hardness of 7. There are two variants. Below 1000 ℃, there is a monoclinic crystal system system (with a density of 5.68g/cm3). At 1000 ℃, a tetragonal system (with a density of 6.10g/cm3) is generated. This crystal transformation is reversible. During cooling, the crystal transformation is accompanied by 7% volume expansion, which can lead to product cracking. Adding stabilizer and Zr02 to form cubic solid solution can eliminate the volume expansion caused by the above crystal transformation. Zirconia has low thermal conductivity (1000 ℃, 2.09W/(m • K)) and a large linear expansion coefficient (9.4 at 25-1500 ℃) × 10-6/℃), with high high-temperature structural strength, and a compressive strength of 1200-1400MPa at 1000 ℃. Good conductivity, with a negative resistance temperature coefficient, with a resistivity of 104 Ω• cm at 1000 ℃ and 6-7 Ω• cm at 1700 ℃. Chemical stability is good, below 2000 ℃, it has no effect on a variety of molten metals, silicates, glass, etc. Solutions of caustic soda, carbonates, and various acids (excluding concentrated sulfuric acid and hydrofluoric acid) have no effect on zirconia.

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