采用Ni-Cr-Nb焊料连接再结晶SiC陶瓷

Joining of Recrystallized SiC Ceramic Using Ni-Cr-Nb Powders as Filler

采用Ni-Cr-Nb(Ni-Cr-Nb的质量比为47.5:49.5:3)焊料连接再结晶SiC陶瓷。正交试验的结果表明,连接温度对接头强度的影响最大,保温时间的影响次之,焊料理论厚度对接头强度的影响最小。最佳工艺参数为:连接温度1400℃、保温时间10min、焊料理论厚度为480μm。在此工艺条件下进行连接试验,接头的三点抗弯强度为75.1MPa,为再结晶SiC陶瓷母材强度的57.8%。断口类型为混合断口,一部分位于连接层,一部分位于SiC陶瓷母材。微观结构研究表明,Ni、Cr和Nb元素与SiC陶瓷母材中的Si和C元素发生了互扩散,形成了反应层和中间层,中间层主要由NbC、Ni2Si和Cr5Si3等组成。

Joining of recrystallized SiC ceramic has been realized using Ni-Cr-Nb powders （consisting of Ni, Cr and Nb powders） as filler. The optimized technological parameters have been obtained by orthogonal experiment, which are joining temperature of 1400 ℃, holding time of 10 min and theoretical thickness of filler of 480 μm. The most effective factor to influence the weld strength is joining temperature within the range of testing. Under the optimized conditions, the maximum relative bending strength of joint, 57.8%, is achieved. The microstructure and phase composition of the weld zone were examined by SEM, EDX and XRD. The results show that interdiffusions and chemical reactions take place in the joining process. A reaction layer and an interlayer are formed in the interracial area of the joints. The interlayer is mainly composed ofNbC, Ni2Si and CrsSi3 .