保护气氛下反应烧结MoSi_2/Al_2O_3复合陶瓷

以金属Mo粉、Si粉和Al粉为原料,采用反应烧结法制备MoSi_2/Al_2O_3陶瓷复合材料,有效增强其室温韧性和强度,并揭示其电阻率随烧结温度变化规律。利用XRD和SEM分析不同温度烧结后MoSi_2/Al_2O_3复合材料试样的物相组成和微观结构;研究不同烧结温度下试样的力学和电学性能。结果表明:在氩气保护气氛下1 200℃时,MoSi_2/Al_2O_3陶瓷复合材料的各项性能较好,其显气孔率为20.7%,体积密度为4.8g/cm~3,断裂韧性值为9.72MPa·m1/2,电阻率为6.0×10~(-2)Ω·cm。所制备的MoSi_2/Al_2O_3陶瓷复合材料物相结构主要由Al_2O_3包覆MoSi_2形成的连续包覆相组成,组织结构均匀。烧结温度为1 200℃时,MoSi2导电相由弥散分布变成相互连接的网络状分布,且Al_2O_3包覆MoSi_2导电相的包覆层变薄,包裹的MoSi_2颗粒之间易于突破包覆相而互相连通,有助于降低电阻率。

Fabrication of MoSi2/Al2O3 composites with reaction sintering method under protective atmosphere

The MoSi2/Al2O3 ceramic composites were prepared by the reaction sintering process,in which the metal Mo,Si and Al powder as the raw material in order to effectively enhance the room temperature toughness and strength of MoSi/Al2O3 composite,and to reveal the resistivity with the purpose of sintering temperature variation.The samples' phase composition and microstructure,sintered at different temperatures,were investigated by SEM and XRD,and the mechanical properties and resistivity were investigated.The experimental results indicate that the MoSi2/Al2O3 ceramic composite shows good performance in the argon protect atmosphere at 1200℃.The apparent porosity is 20.7%,the volume density is 4.8 g/cm3,the fracture toughness value is 9.72 MPa·m1/2,and the resistivity is 6.0×10-2 Ω·cm.MoSi2/Al2O3 composite structure is mainly formed by Al2O3 cladding and MoSi2 continuous cladding phase composition.The organizational structure is symmetrical.When the sintering temperature is 1200℃,MoSi2 conductive phase connects each other to shape interconnected network distribution,and the cladding layer of Al2O3 coated MoSi2 conductive phase become thinner,MoSi2 phase can easy to break the Al2O3 cladding phase to communicate with each other,which is contribute to reduce the resistivity.