Al_2O_3/Ni金属陶瓷力学性能和介电性能的研究

Mechanical and dielectric properties of Al_2O_3/Ni cermet

以热压烧结的方法制备了Al2O3/Ni金属陶瓷,探讨了Al2O3/Ni金属陶瓷显微结构、力学性能及微波介电性能随Ni粒子含量变化的规律。结果表明,在垂直于压力方向上,Ni粒子有明显的受压拉伸现象;当Ni粒子含量从5%（体积分数）增加至20%（体积分数）时,金属陶瓷中Ni粒子的分布由孤立向部分桥连方式转变。随Ni粒子含量的增加,金属陶瓷致密度略有下降,抗弯强度明显降低。与纯氧化铝陶瓷相比,含20%（体积分数）Ni粒子Al2O3/Ni金属陶瓷的断裂韧性提高了50%左右,达到6.4MPa.m1/2。复介电常数测试结果表明,在8.2-12.4GHz频率范围内,金属陶瓷复介电常数的实部和损耗随Ni粒子含量的增加逐渐上升。当Ni粒子含量达到20%（体积分数）时,由于Ni粒子之间的部分桥连现象而使介电常数虚部在一定频段出现负值。

Al2O3/Ni cermet were prepared by hot pressing, and the relationship between their microstructure, mechanical and dielectric properties with Ni particle content were investigated. The results show that some Ni particles are slightly elongated in the direction perpendicular to the pressing direction and are arranged in such away to form large but finite interconnected clusters which do not span the entire specimen up to a volume fraction higher than 20vol%. By increasing the amount of metal in the cermet, the relative density and the bending strength decreased gradually. For cermet, maximum fracture toughness values were 6. 4MPa· m1/2 which increase 50% of the value for alumina. The complex dielectric constant measurements indicate that the real part and the loss increase greatly with the Ni content in the frequency of 8.2-12.4GHz. The imaginary part of dielectric constant of Al2O3-20vol%Ni is negative in value within specific frequency because a properly formed, wellbonded network of Nickel actually occurs.