Silicon nitride protective cover
Aluminum oxide ceramics, silicon nitride ceramics, zirconia ceramics
The main performance of silicon nitride ceramics is as follows: (1) high impact toughness, strength close to corundum, self-wetting and wear resistance; (2) high heat resistance, small linear expansion coefficient, excellent heat transfer Performance; (3) The chemical properties are stable and can withstand strong radiation. The excellent properties of these silicon nitride ceramics have unique products for the high temperature, high speed, and strong corrosive working environment often encountered by modern technology. The very obvious characteristics of its value are: (1) high impact toughness, strength close to that of corundum, self-wetting, wear-resistant and room temperature tensile strength can reach above 980MPa, which can be compared with carbon steel, and is resistant The compressive strength can be maintained until 1200°C without decreasing (2) Good heat resistance, small linear expansion coefficient, and excellent heat transfer performance, so the thermal shock resistance is very good, and the thermal shock resistance from room temperature to 1000°C is not easy split.
Silicon nitride ceramics is an important structural material. It is a superhard substance with low density, lubricity, and wear resistance. Except for hydrofluoric acid, it does not react with other inorganic acids and has excellent corrosion resistance. Strong; anti-oxidation at high temperature. Moreover, it can also resist the shock of cold and heat, and it will not shatter when heated to more than 1000 degrees in the air, and it will not be broken after rapid cooling and then rapid heating. It is silicon nitride that has such good properties that it is often used to make mechanical components such as bearings, steam turbine blades, mechanical seal rings, and permanent molds.
Compared with other ceramic materials, silicon nitride ceramics have many excellent characteristics, such as high theoretical thermal conductivity, good chemical stability, non-toxicity, high flexural strength and fracture toughness, etc. At present, in the research reports on high thermal conductivity silicon nitride ceramics , the thermal conductivity can reach up to 177W·m -1 ·K -1 , and the mechanical properties are relatively excellent (bending strength reaches 460MPa, fracture toughness reaches 11.2MPa m 1/2 ). These characteristics make it considered as a potential heat dissipation and packaging material for high-speed circuits and high-power devices.