摘要
探讨了氧化时间对MoSi_2-RSiC复合材料组成、微观形貌、力学性能和导电性能的影响.结果表明:复合材料氧化主要在外表面生成致密的SiO_2层;材料的力学性能随氧化时间的延长先增大后减小,MS-2.62的抗弯强度和弹性模量在氧化40h后达到最大值,分别为146.03 MPa和239.49GPa,氧化100h后,三种材料的力学性能数据仍高于氧化前;随氧化时间的延长,材料的体积电阻率先减小后趋于平缓,MS-2.62氧化100h后的体积电阻率约为50mΩ·cm,比氧化前减小42%,影响因子的计算表明这种变化可能源于MoSi_2发生塑性变形而减少了复合材料中MoSi_2和RSiC相界面处的微裂纹数量,在一定程度上有利于MoSi_2材料导电性能的充分发挥.
The influence of high-temperature oxidation time on the composition, microstructure, andmechanical and electrical properties of MoSi2-RSiC composites was discussed. The experimental results show that the oxidation of composites mainly formed a dense cristobalite-SiO2 film on the external surface. The mechanical properties of the composites increased and then decreased with the increase of oxidation time, and MS-2.62 oxidized for 40 h achieved the maximal flexural strength and elastic modulus of 146.03 MPa and 239.49 GPa, respectively. Meanwhile, the mechanical properties o{ composites were still greater than those of samples without any oxidation even after 100 h oxidation. With the increase of oxidation time, the volume resistivity of MoSi2-RSiC composites decreased and then reached a flat, while the volume resistivity of MS-2.62 was about 50 m· cm after 100 h oxidation, which was about 42% lower than its o-riginal values. Additionally, the calculated influence factor I indicated that this variety might be caused by the healing of micro-crack at the interface between RSiC and MoSi2 induced by the plastic deformation of MoSi2, resulting in the decrease of the volume resistivity of composites.
出处
《湖南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2017年第6期45-51,共7页
Journal of Hunan University:Natural Sciences
基金
国家自然科学基金资助项目(51372078
51302076)
湖南省自然科学基金资助项目(12JJ4054)
浙江省自然科学基金资助项目(LY14E020009)~~
关键词
MoSi2-RSiC复合材料
高温氧化
力学性能
电性能
MoSiz-RSiC composites
high-temperature oxidation~ mechanical propertieselectrica｜ properties
