大气等离子喷涂MoSi2-30Al2O3电热涂层的组织结构及性能

Microstructure and Property of MoSi2-30Al2O3 Electrothermal Coating Prepared by Atmospheric Plasma Spraying

以MoSi2-30Al2O3混合粉末为原料,利用大气等离子喷涂技术制备MoSi2-Al2O3体系电热涂层。采用XRD、SEM、通电测试、热重-差热分析等对涂层的相组成、组织形貌和热稳定性进行表征。结果表明:MoSi2-30Al2O3电热涂层体系组织均匀致密,添加Al2O3能改善MoSi2的电阻率及低温抗氧化性;MoSi2-30Al2O3涂层电热性能优异,在循环加热测试中,能稳定地加热到320℃并长时间保温,辊面温度分布均匀,中部温差控制在25℃之内;循环加热过程中的氧化及热应力的弛豫会导致涂层产生裂纹及孔隙进而导致涂层电阻率升高。

With MoSi2-30Al2O3 mixed powders as the raw material, MoSi2-30Al2O3 electrothermal coating was sprayed by atmospheric plasma spraying technology. The phase composition, microstructure and thermal stability of the coating were systematically studied by XRD, SEM, electrical test and differential thermal gravity analysis. The results show that MoSi2-30Al2O3 electrothermal coating shows dense microstructure. Al2O3 can improve the electrical resistivity and oxidation resistance of MoSi2 materials in low temperature. The coating exhibits an excellent electrical-heating performance. In the heating cycle test, it could be heated to 320 ℃ stably and exhibit uniform thermal distribution in the surface area. The temperature variation in roll’s central area can be controlled within 25 ℃;Oxidation and thermal stress relaxation during heating cycle would generate cracks and pores in the coating which would increase electrical resistivity.