Preparation Of SiC Ceramic Materials By Reaction Melt Infiltration On Low Tempertation And Study On Microstructrue And Performances Of The Materials

Reaction-bonded Silicon Carbide(RBSC) is a multiple phase ceramic composed with SiC and free Silicon,and in some situation it contains free Carbon as well. RBSC has excellent performance,such as high temperature strength,corrosion resistance,thermal shock resistance and high temperature anti-oxidation properties.In theory,the breaking strength of ceramic materials increase with the grain size to reduce.We explore this issue by lowering the sintering temperature to control the generation of the SiC grain size,In this paper,the purpose of this subject study is to explore the possiblity to prepare RBSC materials which get high-density or high-performance at low temperacture,and to discuss the influencing factors to the microstructure and performance of materials and there regularity.Another purpose of this study is to generalize the relationship between microstructure and performance of the RBSC ceramic materials.The results showed that we can get prepared RBSC ceramics at the point which is more than in the silicon melting point 30～60℃by Reaction sintering.In this paper,The RBSC ceramics had been prepared by dry pressing with 3.5μm SiC,which tonerdensity of 0.91g/cm³ and exhibit density of 3.16g/cm³;The RBSC materials get the fracture strength 594MPa by In-situ solidification forming.The influence of processing parameter to microstructure of green body and density of the ceramics were discussed.In situ coagulation molding process,in order to obtain high solid slurry of low viscosity,the experiments carried out on the surface of SiC powder coated modification.By analyzing the different capability between modified-coated and uncoated SiC powder,such as the infrared spectrum,Zeta Potential and solid content. The solid content of slurry which contain 1.2μm coated SiC and toner powder is 59.04vo1%,higher than uncoated SiC 41%.Results of the experiment show that:The strength is not up to the density,and the material which density is highest doesn't have the biggest fracture strength..There is lettle f_Si in this sintered body of RBSC,but silicon plaque accumulation.There is clearly improved performance between Initial powder and pretreatment, by the same formula and process of preparation of the sintered bodies.Replace part of graphite carbon black to increase the density of sintered bodies,but it can not improve the mechanical properties.The micro-hardness of RBSC ceramics sintered is influenced by density,With the molding pressure increases,material microhardness increased.When sintered keep a certain density,thesmaller grain size the sintered has,the greater the material's micro-hardness.