微波烧结制备MoSi2 及SiC/ MoSi2 纳米复合陶瓷

采用微波烧结法制备了MoSi2和10vol%SiC/MoSi2纳米复合陶瓷。通过SiC预加热体的混合式加热法和合理的保温结构设计,实现了MoSi2低温阶段的快速升温,提高了温度均匀性。密度和力学性能测试结果表明,1 450℃保温60 min烧结工艺下,MoSi2试样的相对密度达到93.4%,断裂韧度4.5 MPa.m1/2,维氏硬度为10.53 GPa,弯曲强度为186 MPa。10vol%SiC/MoSi2试样尽管相对密度下降为90.3%,但各项力学性能均优于MoSi2试样。相比1 650℃热压烧结,微波烧结温度降低了200℃,MoSi2和SiC/MoSi2试样致密性有所下降,但力学性能有较大提高,尤其是MoSi2试样。断口扫描分析表明,微波烧结试样相对热压烧结试样基体晶粒更细,孔隙细小且分布均匀;SiC/MoSi2试样微波烧结的晶粒细化效果不如MoSi2明显。

Microwave Sintering of MoSi2 and SiC/ MoSi2 Nanocomposite Ceramics

MoSi2 and SiC/MoSi2 nanocomposite ceramics were prepared by microwave sintering.Hybrid heating using SiC as preheating material and reasonable design of heat preservation system realized the fast elevation of temperature of MoSi2 on the low temperature stage,and enhanced the temperature uniformity of MoSi2.The density and mechanical properties tests showed that under the sintering parameters of 1 400℃ and holding 60 min,the properties of pure MoSi2 sample achieved relative density of 93.4%,fracture toughness 4.5 MPa·m1/2,Vickers hardness 10.53 GPa,and bending strength 186 MPa.All the mechanical properties of 10vol.%SiC-MoSi2 were superior to that of pure MoSi2,though the relative density decreased to 90.3%.The temperature of microwave sintering MoSi2 and SiC/MoSi2 samples decreased 200℃ lower than hot-pressing sintering temperature(1 650℃),but the mechanical properties are actually enhanced greatly,in particular MoSi2 sample.Fracture surfaces indicated that compared to hot-pressing sintered samples,the microwave sintered samples presented refined grain size,fine and uniform pore.However the effect of grain refinement of microwave sintering to SiC/MoSi2 is weaken compared to pure MoSi2 sample.