Joining Of SiC Ceramic By Spark Plasma Sintering Technology

SiC ceramic has many properties such as high hardness, good thermalconductivity, high temperature resistance, high strength at high temperature, goodcorrosion resistance and anti-oxidation, etc. But the inherent properties of siliconcarbide such as low ductility and high brittleness make it difficult to machining. Inactual using, we often need to connect small or simple shapes of silicon carbide to alarge and complex component. Therefore, reliable connection technology is thepremise of making good use of the excellent properties of SiC ceramic. At present,using inorganic nonmetallic materials as interlayer to connect SiC ceramic has greatprospects for development.Ti₃SiC₂has the properties of metal and ceramic simultaneously. It has goodthermal conductivity, electrical conductivity like a metal, and it has ductility at roomtemperature and plastic under high temperature. Meanwhile, it has high melting point,anti-oxidation, corrosion resistance, good thermal shock resistance and other physicaland chemical properties like a ceramic. Thererore, using Ti₃SiC₂as interlayer toconnect SiC ceramic can satisfy the application under high temperature. Moreimportant, it can relieve the residual thermal stress caused by high temperaturereduced to room temperature through its plastic deformation, thereby it can furtherimprove the high temperature strength.In this paper, we research the effect of adding appropriate Si and Al to fabricatepure Ti₃SiC₂material through SPS method. And the impact of sintering temperatureon the purity of Ti₃SiC₂was investigated. Through the study we found that adding0.2mole excess Si into3Ti/Si/2C to offset the loss of Si is in favor of the synthesis ofTi₃SiC₂and increasing the Ti₃SiC₂purity of products. The addition of0.2mole Al canalso increase the purity of Ti₃SiC₂. Finally the high purity of Ti₃SiC₂was preparedfrom3Ti/1.2Si/2C/0.2Al at1300℃by SPS. The purity of Ti₃SiC₂is about99wt%.And the Ti₃SiC₂grains grow equally and well develop, the average grain size is15²0μm.We connect SiC ceramic with different interlayer through SPS technique, studythe influence of different temperature to the strength of connections and do three point bending test to the connection at room and high temperature. The room temperatureresults show that the SiC ceramic connected with3Ti+1.2Si+2C+0.2Al at1600℃have the highest strength at room temperature, the value is133.3MPa. The hightemperature results show that the samples connected with Ti₃SiC₂have lower strength,but the strength of samples connected with3Ti+1.2Si+2C+0.2Al and TiC+Si aremuch higher, the value got at1200℃is118.9MPa and84.6MPa respectively. Bycomparing we can get that the bending strength of samples connected with Ti₃SiC₂arelower under room and high temperature; the samples connected with TiC+Si have thelowest strength at room temperature, but it have better strength at high temperature;the samples connected with3Ti+1.2Si+2C+0.2Al both have high bending strengthunder room and high temperature, and the effect is good.