轴向送粉等离子喷涂Ni/Al_2O_3涂层的力学及微波介电性能

Mechanical and Dielectric Properties of Ni/Al_2O_3 Composite Coatings Prepared by the Axial Plasma Spraying

以轴向送粉等离子喷涂法制备了Ni/Al2O3陶瓷涂层,分析了Ni含量变化对涂层材料的显微结构、力学性能及微波介电性能的影响.结果表明,随着Ni含量增加,涂层中Ni粒子的分布逐渐由孤立向部分桥连方式转变;陶瓷涂层的相对密度、抗弯强度呈下降趋势,这主要是由于在陶瓷涂层中Ni与Al2O3不润湿,Ni与Al2O3热膨胀系数不匹配从而形成空隙引起的.涂层断裂韧性随Ni含量的增加而升高,则是由于材料中Ni粒子发生了延展变形和引起裂纹转向.复介电常数性能测试结果表明,在8.2～12.4GHz微波频率范围内,陶瓷涂层复介电常数的实部值随Ni粒子含量的增加先逐渐上升后逐渐下降,复介电常数的虚部上升.这与Ni粒子形成的桥连结构有关.

The nickel-alumina composite coatings were fabricated by the axial plasma spraying method.The effects of the different content of Ni on the microscopic structure,mechanical and dielectric properties of the composite coat-ings were investigated.The results indicate that with the increase of nickel content,the distribution of Ni particles changes from separated to large but finite interconnected clusters.The relative density and the bending strength de-crease gradually,which is attributed to thermal expansion mismatch and non-wettability between alumina and nickel.The increase in the fracture toughness is caused by the Ni particles＇ extension and deflection of the crack.The com-plex dielectric constant measurements indicate that the real part shows an increase and then decline trend with the Ni content in the frequency of 8.2？12.4GHz,while the imaginary part continues increasing.This is ascribed to the bridge structure of Ni particles.