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What Are The Advantages Of Vacuum Sintered Materials?

As an important structural ceramic material, silicon carbide is used in high-temperature kiln furniture and combustion nozzles due to its excellent high-temperature mechanical strength, high hardness, high elastic modulus, high wear resistance, high thermal conductivity, corrosion resistance and other properties. , heat exchangers, sealing rings, sliding bearings and other traditional industrial fields.
Silicon carbide ceramic sintering technology
Silicon carbide reaction sintering
Reaction-sintered silicon carbide was first proposed by P. Popper in the 1950s. The process is to mix carbon source and silicon carbide powder, prepare a green body through slip molding, dry pressing or cold isostatic pressing, and then siliconize it. Reaction, that is, heating the green body to above 1500°C under vacuum or inert atmosphere, solid silicon melts into liquid silicon, and penetrates into the green body containing pores through capillary action. A chemical reaction occurs between liquid silicon or silicon vapor and C in the green body, and the β-SiC generated in situ combines with the original SiC particles in the green body to form a reaction-sintered silicon carbide ceramic material.
In order to obtain reaction-sintered silicon carbide with better performance, methods such as changing the size and type of carbon source, particle size of silicon carbide raw material, porosity of the green body, sintering temperature and holding time are often used.

The advantages of reaction-sintered silicon carbide are low sintering temperature, low production cost, and high degree of material densification. In particular, there is almost no volume shrinkage during the reaction sintering process, and it is especially suitable for the preparation of large-sized and complex-shaped structural parts. High-temperature kiln furniture materials, radiant tubes, heat exchangers, desulfurization nozzles, etc. are all typical applications of reaction-sintered silicon carbide ceramics.
Resistance heating vacuum hot press sintering
The mechanical pressure provided during the hot-press sintering process increases the driving force for densification by enhancing the rearrangement of particles in the early stages of sintering. After reaching a relatively high density, the mechanical pressure effect can reduce porosity while inhibiting grain coarsening.
Compared with normal pressure sintering, hot press sintering can achieve densified sintering at a relatively lower temperature, thereby forming a good microstructure and improving its mechanical properties. When sintering aids and hot pressing are used at the same time, the sintering time and sintering temperature of silicon carbide can be significantly shortened.