SiO2f/SiO2复合材料自身及其与铜、不锈钢的钎焊

采用AgCuTi活性钎料,在880℃/10min规范下成功实现了SiO2f/SiO2自身、SiO2f/SiO2与Cu和SiO2f/SiO2与1Cr18Ni9Ti三种接头的连接。实验结果表明,三种接头中靠近SiO2f/SiO2母材的界面处均形成了一层薄薄的扩散反应层组织,反应层中出现了Ti和O的富集,根据两者的原子比例推断生成了TiO2相;另外,三种接头中心区都形成了由灰色相和白色相共同组成的Ag-Cu共晶组织,其中灰色相为Cu基固溶体,白色相为Ag基固溶体。接头剪切强度结果显示,SiO2f/SiO2/Cu接头剪切强度为12.4MPa,SiO2f/SiO2/1Cr18Ni9Ti接头剪切强度为18.4MPa,接头中的残余应力是决定接头强度大小的重要因素之一。

Brazing of SiO2f/SiO2 , SiO2f/SiO2/Cu and SiO2f/SiO2/stainless steel joints

Brazing of SiO2f/SiO2,SiO2f/SiO2/Cu and SiO2f/SiO2/1Cr18Ni9Ti joints was carried out at 880℃ for 10 min using Ag-Cu-Ti brazing foils and sound joints were achieved.The results showed that a thin diffusion layer was formed close to the interface of SiO2f/SiO2 matrixes in the three kinds of joints.Elements Ti and O were enriched and TiO2 phase was formed in the diffusion layer.Additionally,in the three brazing seams,Ag-Cu eutectic structures were formed,being made up of white Ag-based solid solution and grey Cu-based solid solution.The shear strengths of SiO2f/SiO2/Cu and SiO2f/SiO2/1Cr18Ni9Ti joints were 12.4 MPa and 18.4 MPa respectively.One of the key reasons for the low joint strengths is the large residual thermal stress caused by the mismatch of thermal expansion coefficient between the SiO2f/SiO2 composite and the metals to be joined.