放电等离子烧结原位合成MoSi_2-Mo_5Si_3复合材料的组织与性能

Microstructure and properties of MoSi_2-Mo_5Si_3 composites in-situ synthesized by spark plasma sintering

以Mo,Si粉为原料,采用放电等离子烧结(SPS)原位制备MoSi_2-Mo_5Si_3复合材料,研究不同烧结工艺下材料的微观组织和室温力学性能,并探讨Mo_5Si_3含量对复合材料力学性能、高温氧化和高温摩擦磨损性能的影响。结果表明:在1200℃温度以上SPS能够合成MoSi_2-Mo_5Si_3复合材料。随着烧结温度的升高,复合材料的致密化效果明显加强,但其硬度、抗弯强度和断裂韧性都呈现先升高再降低的趋势;随着烧结压力的提高,复合材料的致密度、硬度和抗弯强度增加,断裂韧性先提高后保持不变;保温时间由3 min增加到9 min时,复合材料的力学性能先提高然后基本保持不变。Mo_5Si_3含量为25%时,MoSi_2-Mo_5Si_3复合材料的力学性能最佳,其相对密度为98.72%,硬度、抗弯强度和断裂韧性分别为11.27 GPa、331 MPa和5.33 MPa·m^(1/2)。随着Mo_5Si_3含量增加,MoSi_2-Mo_5Si_3复合材料在1200℃的高温抗氧化性能和1000℃的高温耐磨性能都逐渐降低。

MoSi_2-Mo_5Si_3 composites were prepared by spark plasma sintering（ SPS） using Mo and Si powders as raw materials,and the effects of sintering process on microstructure and mechanical properties of the MoSi_2-Mo_5Si_3 composites were studied,and the effects of the content of Mo_5Si_3 on high temperature oxidation resistance,friction and wear properties of the MoSi_2-Mo_5Si_3 composites were also investigated.The results show that the MoSi_2-Mo_5Si_3 composites can be prepared successfully by SPS process with the sintering temperature above 1200 ℃.With the increasing of the sintering temperature,the relatively density of the MoSi_2-Mo_5Si_3 composites increases,while the hardness,flexure strength and fracture toughness first increase and then decrease.With the increasing of sintering pressure,the density,hardness and flexural strength of the MoSi_2-Mo_5Si_3 composites increase,while the fracture toughness first increases and then remains unchanged.With the increasing of sintering time from 3 min to 9 min,the mechanical properties of the MoSi_2-Mo_5Si_3 composites first increase and then keep constant.The optimal mechanical properties of the MoSi_2-Mo_5Si_3 composites are obtained with25% content of Mo_5Si_3,of which the relatively density,hardness,flexure strength and fracture toughness are 98.72%,11.27 GPa,331 GPa and 5.33 MPa·m^（1/2）,respectively.With the increasing of the Mo_5Si_3 content,the oxidation resistance at 1200 ℃ and the wear resistance at 1000 ℃ of the MoSi_2-Mo_5Si_3 composites decrease.