纳米Ni粉填料对聚硅氮烷连接SiC陶瓷接头性能的影响

Effect of Nickel Nanopowders Addition on Joining Property of Silicon Carbide to Itself by Polysilazane

研究了活性填料纳米Ni粉对陶瓷先驱体聚硅氮烷连接反应烧结SiC陶瓷接头性能的影响,同时与惰性填料纳米SiC粉及活性填料微米Ni粉进行了对比,指出填料的种类及颗粒度对连接强度均有较大影响。活性填料纳米Ni粉的加入可减少连接层内的孔隙和裂纹,同时还可以与聚硅氮烷的裂解产物及母材发生反应,促进聚硅氮烷的裂解,从而降低连接温度,提高连接强度。当连接温度为1200℃时,其最大抗弯强度达到251.6MPa。微观研究表明,连接层结构较为均匀致密,且与母材间界面结合良好。惰性填料纳米SiC粉对连接强度没有明显改善。微米Ni粉因不能与先驱体形成均匀的连接层而导致连接强度降低。

Joining of reaction-bonded silicon carbide （RBSiC） to itself has been realized using polysilazane with nickel nanopowders, silicon carbide nanopowders and nickel micropowders being taken, as joining materials respectively. The joining strength of the joints is strongly affected by the kind and granularity of the additions. Adding nickel nanopowders, as an active addition, can effectively reduce holes and cracks in the joining interlayer and accelerate pyrolysis of polysilazane, therefore it can enhance the joining strength and lower joining temperature. The maximum bending strength of the joints is 251.6 MPa, which is 75.6% of the strength of silicon carbide. This value is obtained at the joining temperature of 1200℃ and after the reinforcement for 3 times. Microstructural studies reveal that the joining interlayer is uniform and densified. Good contact at the interfaces is visible on the SEM photograph. Silicon carbide nanopowdes, as an inert addition, have little improvement for joining strength, nickel micropowders addition can not form an uniform joining interlayer with polysilazane, causing the low joining strength.