Preparation And Properties Of SiC Particles/Pyroxene-based Glass Ceramic Composites

Combining with SiC secondary phase with high elastic module,high strength and high thermal-mechanical property has been proved to be a feasible method to improve the properties of the traditional glass ceramics.However,such composite materials are normally produced through a hotpress assisted procedure.This feature is the main obstacle restricting the further application of the material.Therefore,it is of great importance to develop a new production procedure without using hot-pressing.In this field,the study is in its primitive stage.As a result,this paper tended to develop a hot-pressing-less procedure to develop SiC particle/Diopside based glass-ceramic composite.Deducing or inert protecting atmosphere that has been widely employed in the conventional fabricating procedure was replaced by graphite powder reducing agent.The hot-pressing assisted sintering was replaced by the convention the convention oxide ceramic procedure.Using the as fabricated composite as the model material,the effects of using graphite powder as the reducing agent and varying ball milling,sintering temperature,nucleating temperature and crystallization temperature,were investigated.The following results were obtained:The three-step procedure that was used to fabricate SiC fiber/Diopside based glass ceramic composite in our research group was successfully adapted to fabricate SiC particle/Diopside based glass ceramic composite.The procedure was consisted of nucleating at 740℃,crystallizing at 870℃and sintering at 1050℃ for 2h respectively.The as fabricated composite has three crystalline phases,i.e.diopside,anorhtite sodium and SiC.The sample containing 10wt%of SiC particle and sintered at 1050℃ shows the optimum properties.It has a density of 2.51 g/cm3,a linear shrinkage of 9.18%,a Vickers hardness of 4.52 GPa and a surface roughness of 82.2.With the further addition of SiC particle,more pores form within the composite sample,thereby deteriorating the overall property of the as fabricated composite materialThe sample without the addition of SiC particle can be fully sintered at temperatures merely above 800℃.Inspired by this phenomenon,three new fabricating processes without the final high temperature sintering procedure were designed:Ⅰ.nucleating at 740℃ for 2 h and crystallizing at 1000℃ for 2h;Ⅱ.nucleating at 740℃ for 2h and crystallizing at 870℃ for 2h;Ⅲ.nucleating at 740℃ for 2h and crystallizing at 840℃ for 2h.The relative results show the process Ⅲ is the optimum one.On the base of the process Ⅳ,the effect of further varying the nucleating temperature within the range of 740-800℃ and the increase of crystallizing temperature from 840 to 880℃ was studied.The result shows the combination of nucleating at 780℃ and crystallizing at 860℃ is the optimum process.Under this condition,the sample with 10wt%SiC particle shows the best over properties.It has a bending strength of 120 MPa,a Vickers hardness of 5.71 GPa,a fracture roughness of 2.22 MPa× m1/2.The composite is a feasible candidate for the application in the structural field.The overall result of this study can be a good reference to fabricating SiC particle/glass ceramic composite at low cost.