MoSi2含量对MoSi2/Al2O3复合涂层介电与力学性能的影响

摘要

Molybdenum disilicide (MoSi2) sheath and aluminum oxide (A12O3) core blended powders were fabricated by spray drying.A derived coating material was produced for the application as microwave absorbers using the as prepared powders by atmospheric plasma spray (APS) technology.The effects of MoSi2/Al2O3 mass ratio on the dielectric and physical mechanical properties of the composite coatings were investigated.When the MoSi2 content of the composites increases from 0 to 45％,the flexure strength and fracture toughness improve from 198 to 324 MPa and 3.05 to 4.82 MPa·m1/2 then decline to 310 MPa and 4.67MPa·m1/2,respectively.The dielectric loss tangent increases with increasing MoSi2 content,and the real part of permittivity decreases conversely over the frequency range of 8.2-12.4 GHz.These effects are due to the agglomeration of early molten MoSi2 particles and the increase of the electrical conductivity with increasing MoSi2 content.%通过喷雾干燥法制备MoSi2包覆A12O3的壳核结构混合粉,利用该混合粉以等离子喷涂技术制备MoSi2/Al2O3复合涂层材料.研究MoSi2/Al2O3质量比涂层材料的力学和介电性能的影响.结果表明:随着MoSi2含量从0增加到45％,复合材料的抗弯强度和断裂韧性分别从198MPa和3.05 MPa·m1/2增加到324MPa和4.82MPa·m1/2,随后又降到310 MPa和4.67 MPa·m1/2.在8.2-12.4 GHz微波频率波段内,随着MoSi2含量的增加,复合材料的介电损耗增加,而介电常数的实部却呈减小趋势.这主要是由于MoSi2颗粒熔化后的凝聚及导电网络结构的形成导致电导率的增加引起的.