Silicon nitride ceramic classifying wheel
Aluminum oxide ceramics, silicon nitride ceramics, zirconia ceramics
Silicon nitride ceramics have good chemical stability. Except for hydrofluoric acid and concentrated NaOH corrosion, they can resist the corrosion of all inorganic acids and some alkali solutions, molten alkalis and salts. The metal is stable and will not be wetted or corroded. Silicon nitride has good oxidation resistance. The oxidation resistance temperature can be as high as 1400 ° C. It is stable in a dry oxidizing atmosphere below 1400 ° C. Its service temperature can generally be as high as 1300 ° C. It can even be successfully applied to 1800°C in a neutral or reducing atmosphere. In humid air at 200°C or dry air at 800°C, silicon nitride reacts with oxygen to form a protective film on the surface of SiO2, which hinders the continued oxidation of Si 3N 4 .
If silicon nitride ceramics with high temperature resistance and low heat transfer are used to make the heating surface of high temperature wear-resistant parts, it can not only reduce the weight of the product itself, save fuel, but also improve thermal efficiency. Silicon nitride ceramic is an inorganic material ceramic that does not shrink during sintering.
Silicon nitride has high strength, especially hot-pressed silicon nitride pipe fittings, which have high strength, low density, high temperature resistance and other properties.
First of all, the reason why silicon nitride ceramic bushings can work in certain environments and conditions is due to the function of silicon nitride ceramics. Friends who know something about silicon nitride ceramics know that the elastic modulus of silicon nitride is much higher than that of metal, and elastic deformation after stress can reduce the vibration of machine tools to a certain extent, so there are many ultra-fine machine tools Silicon nitride ceramic materials are used for the main shaft and the very high-precision aerospace bushing.
The second advantage is: because silicon nitride ceramics have high hardness, the bushing made of silicon nitride ceramics has very good wear resistance. In addition to these, the mechanical strength of silicon nitride ceramics is also very high. Its tensile strength and bending strength are similar to metals, and its compression resistance is very strong, especially under high temperature conditions. Silicon nitride ceramic bushings It can still maintain high strength and hardness. Compared with bushings made of other materials, silicon nitride ceramic bushings are longer.
We all know that the friction coefficient of silicon nitride ceramics is very small, and the silicon nitride ceramic bushing has low heat generation performance. Compared with metal materials, the thermal conductivity of silicon nitride ceramics is very poor, resulting in the silicon nitride ceramic shaft There is very little heat generated during operation. Therefore, silicon nitride ceramic bushings have been favored by many industries.