How Many Oxide Structural Ceramics Do You Know? (2)
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Magnesium Oxide (MgO) Ceramic
Magnesium oxide ceramics are ceramic with magnesium oxide as the main component. It belongs to the cubic crystal system and the melting point of which is 2800 ℃. Magnesium oxide is volatile in temperature of higher than 2300 ℃, therefore, magnesium oxide products are generally restricted to use below 2200 ℃.
Magnesium oxide ceramics can be used as weakly alkaline materials, crucibles for smelting metals, the mold for casting metals, protective tubes for high-temperature thermocouples, and furnace lining materials for high-temperature furnaces.
Transparent magnesium oxide ceramics can be used as radar cover, infrared detector cover, chemical window material, etc. However, thermal shock resistance of which is so poor that difficult to be sealed by ceramic metal, and it is easy to evaporate in the air, so it is not suitable for high-pressure sodium lamp.
Mullite ceramic refers to the ceramic of the main crystal phase for mullite.
Due to the excellent thermal properties and mechanical properties while the not outstanding room temperature performance of mullite, high-purity mullite ceramics are mainly used in the high-temperature environment:
High-temperature insulation parts, such as used as cylinder head floor in the advanced ceramic engine;
Used as heat exchanger components, such as core tube, thermocouple tube furnace, and crucible, used for sintering ceramic element at more than 1000 ℃ instead of stainless steel;
Mullite ceramics have good corrosion resistance of gases and airtightness, which is suitable for the production of protective tubes.
High-temperature pads and nozzles.
Zirconia Toughened Alumina (ZTA) Ceramics
Zirconia toughened alumina ceramics is a kind of compound material that is used to induce phase change with the toughening of zirconiaand to inhibit the growth of the grain of alumina body. Compared with a single alumina ceramic, it has a higher flexural strength and fracture toughness.
ZTA Composite ceramics can be made of ceramic tools or used for the processing of cast iron and alloy
ZTA ceramics can be used to make the interface structure of engineering ceramics to extend the service life of engineering materials.
Used to make wear-resistant porcelain ball.
Used as a biomedical material for the reconstruction and repair of hard tissue (teeth).
Zirconia Toughened Mullite (ZTM) Ceramics
Zirconia toughened mullite ceramic is a kind of zirconia phase change toughened ceramics with mullite as the matrix.
Mullite has a high temperature, high strength, good fracture toughness, chemical stability and thermal shock resistance. Adding zirconium dioxide toughened mullite, there are two toughening mechanisms of stress-induced phase change and microcrack toughening.
Zirconia toughened mullite ceramics can be used to make tools and some parts of an adiabatic engine.