The Study on the Mechanical Properties of SiC/Si_3N_4 Compound Materials

Abstract: Si_3N_4's pottery and porcelain density is low and hardness is high and the coefficient expanding in heat low and thermal conductivity is good and the oxidation resistance is good, and possesses many fine functions such as good high temperature strength as heat-resisting shake and quality are light etc,but owing to the fact that his toughness shortcoming makes his apply suffering placing restrictions on,therefore often adopting fibre,whisker and anything small and roundish to come to increase pliable but strong(ly).Among them fibre and whisker increase the splitting action that the pliable but strong compound material possesses the similar metal,insensitive to the crack,the reliability is high,but the cost is too high;The anything small and roundish compound material cost is low,and to fibre and metal whisker composite is kind to replenish.In this text,chiefly studied the different SiC content to serve as 5%,15%and 25%,and spreading certainly to burn to compose the mechanics function of compound powder of (SHS)SiC/Si_3N_4 and SiC/Si_3N_4's compound material that the mixed powder of machinery is prepared,and studies content and result as follows:(1)study the different SiC content to serve as 5%,15%and 25%,the compound material that SHS's law is prepared and the mechanics function of mechanical mixed material.The results show that the properties of SiC/Si_3N_4 composite with 15wt%SiC content were significantly superior compared with others;And the mechanics function of mixed material of machinery is superior to that SHS's law is directly synthetis;(2)study the different sintering technology and the different influences to the compound material mechanics function of dry pressing pressure as well as opening or hole in a utensil, etc.and addition agent.The result shows,and these factors all can be given rise to the very big influence to the mechanics function of compound material;(3)study formation mechanism of SiC/Si_3N_4's compound material structure.The original so exists in the brilliant nuclear of Si_3N_4 with two kinds of different structures.One kind is the original so anything small and roundish exists in the brilliant nuclear of Si_3N_4,the original is so-and Si_3N_4's compound material formed the microstructure structure of interior crystalline substance mould;Another kind is the original so anything small and roundish exists in the brilliant nuclear of Si_3N_4 and between brilliant nuclear,the original is so-and Si_3N_4's compound material formed interior crystalline substance mould microstructure structure and interior crystalline substance/grain boundary mould microstructure structure;(4)study the apparent minute structure and mechanics function on SiC/Si_3N_4's compound material.The specially designated or appointed structure was decided the peculiar function of material,and analysing finding,the mechanics function that is apparent minute structure and material of compound material is closely linked;(5)SiC/Si_3N_4's compound material increases pliable but strong mechanism.The discovery chiefly has two-phase to expand in heat in SiC strengthens SiC/Si_3N_4's compound material the coefficient difference that what causes expands in heat increases has suitably between pliable but strong mechanism and the two-phase interface that the strong interface combines intensity causes increases crack bridge antithetical couplet and crack deflection pliable but strong machine-processed as well as that long and thinĪ²-Si_3N_4 causes and increases pliable but strong mechanism,these several kinds increase equal the splittingaction that can influence the material of pliable but strong mechanism,thus influences the mechanical function of material…
Key words: compound material; toughness; bend strength; fracture toughness; mechanical function; microstructural structure

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