Graphite, as the evaporation source material of early metal deposition, has many excellent properties, such as good high temperature resistance, thermal stability, good electrical conductivity, and good thermal shock resistance. However, the graphite material is easy to oxidize at high temperature and react with the vapor deposited metal, resulting in cracking of the crucible and affecting its service life. Hexagonal BN and graphite have the same crystal structure, very similar thermal expansion coefficient and thermal conductivity, and excellent cold and thermal cycle impact resistance. It is the most ideal thermal matching system. In addition, BN has high corrosion resistance to molten metal
Good, with good high-temperature electrical insulation and mechanical processing performance. If graphite and hexagonal BN are made into C / h-BN laminated composite materials, C / h-BN materials can maintain single-phase properties and have both excellent properties according to the additivity of the composite materials. This provides great possibilities for designing and manufacturing new heat matched evaporation source materials with high thermal shock resistance. In this paper, C / h-BN layered composites were prepared by hot pressing sintering and SPS sintering,
Through the design of the interface layer between graphite layer and BN layer, the effects of sintering mode, sintering temperature, holding time, BN layer thickness, intermediate layer composition and other parameters on the structure and properties of the material were studied. In the hot press sintering study of C / h.bn layered composites, the density of BN increased with the increase of sintering temperature. With the increase of sintering temperature, the bonding state of the material interface gradually improved, and there was a
Crossing area. The higher the sintering temperature, the higher the interlayer bonding strength of the layered composites; The results show that too long holding time is unfavorable to the mechanical properties of the material, and the thermal shock resistance of the material gradually increases with the increase of sintering temperature. C / h.bn layered composites were prepared by SPS sintering technology. It was found that with the increase of sintering temperature
The density of BN also increases gradually. Too long holding time at high temperature is unfavorable to BN densification and material interface bonding. This may be related to the abnormal growth of BN grains. With the increase of sintering temperature, the element diffusion intensifies. The thicker the transition layer, the higher the interfacial bonding strength of the material, and the better the bonding between the graphite layer and the BN layer. The thermal shock resistance of the sample also gradually increases with the increase of sintering temperature in the short holding time. However, the thermal shock resistance of the sample increases first and then decreases in the longer holding time (15 rain)
Small. With the increase of BN thickness, the bonding condition of the interface is gradually deteriorated. The results show that proper interlayer is beneficial to the interlayer bonding of C / h-BN laminated composites. Middle layer
And the material system is a1.bn mixture. The aluminum content of the intermediate layer is 20wt%, 40wt%, 60wt% and 80wt%
Were sintered. It was found that when the aluminum content was low, the main product of the intermediate layer was A1N. With the increase of the aluminum content, the more A1N was generated in the intermediate layer. When the aluminum content reached 80wt%, the polarity
A small amount of a14c3 was generated. Compared with SPS sintering, hot press sintering takes a longer time and has an impact on the material interface