Sn含量对银钎料焊接性的影响

Abstract

通过往Ag-Cu-Zn系钎料内添加适量的Sn和Ni元素，利用OM、SEM、XRD研究了钎料内Sn含量对钎料组织与焊接性能的影响。结果表明：Ag-Cu-Zn系钎料内主要成分为：Ag基固溶体；Cu基固溶体；CuZn化合物；当Sn含量达到4 wt%时，出现少量的Ag2Cu2O化合物。在本研究设计的成分范围内，钎料内并未出现Cu-Sn金属间化合物。差热分析表明：随着Sn含量的增加，钎料的固液相线温度均出现不同程度的下降。润湿试验表明：相同的加热温度下，不同Sn含量的银钎料均可对不锈钢形成良好的润湿。此外，采用该系列钎料手工火焰钎焊了不锈钢与不锈钢，得到的接头内母材/钎料界面处形成了致密的连接，无缺陷存在；当Sn含量为3.0 wt%时，得到接头的最高拉伸强度达到了450 MPa；当Sn含量超过3.0 wt%时，由于钎料内少量氧化物的存在使接头性能出现大幅度下降。 Sn and Ni element were introduced into Ag-Cu-Zn filler alloy, and the effect of Sn content on microstructure and brazing properties of Ag based filler alloy was analyzed by OM, SEM and XRD. The results indicated that the Ag-Cu-Zn filler alloy was mainly comprised of Ag based solid solution, Cu based solid solution and CuZn compounds. A trace amount of Ag2Cu2O occurred in the filler alloy while the content of Sn exceeded 4 wt% in the filler. However, the Cu-Sn intermetallics were not detected in the range of composition in the research. By using DSC analysis, the melting temperature of the filler alloy was decreased with increasing Sn content. The wettability test showed that the stainless steel could be wetted by the Ag-Cu-Zn based filler alloy with different Sn content. Besides, this kind of filler alloy was used to join stainless steel by torch brazing, and a compact bonding could be obtained at the substrates/filler alloy interface. The maximum joint strength could reach 450 MPa while the filler contained 3.0 wt% Sn element. While the content of Sn exceeded 3.0 wt% in the filler, the joint strength decreased sharply due to the existence of few oxides.