接触反应法解决铝/不锈钢钎焊的缺陷及脆性

Resolve of fragile and defect problem for a new contact reaction brazing aluminum to stainless steel

为满足不锈钢电加热餐具生产的需要,提出采用接触反应钎焊的方法实现复合电热餐具的铝热管与铝板、铝板与不锈钢板结构的高致密连接.研究表明:Si中间层介质与铝基体之间的共晶反应所产生的Al-Si共晶液相,能够将铝加热管与铝板、铝板与不锈钢板大面积结构致密地连接在一起;接触反应钎焊初期存在Al/Si固相扩散反应的液相反应萌生,该过程与加热阶段Si的固态扩散、液相层扩展和成分均匀化共同构成接触反应钎焊接头成缝过程;接触反应钎焊初期液相反应萌生以Al/Si固相界面的扩散为主要控制过程,其受控干Si向Al基体内的固相扩散速率,液相层的扩展和成分均匀化受控于Al在Al-Si液相中的扩散速率,是液相产生的主要阶段;接触反应钎焊依靠反应液相层的阻隔延迟效应,限制了铝/不锈钢异种材料间脆性化合物的生成,使得反应层薄,钎缝强度高.

For the sake of the manufacture of stainless steel composite electro-thermal cooker, a new idea u-sing contact reactive brazing for the close joining of aluminum electro-thermal tube to aluminum sheet and aluminum sheet to stainless steel sheet in composite electro-thermal cooker was put forward. Microstructure analysis of the joint showed that, aluminum electro-thermal tube to aluminum sheet and aluminum sheet to stainless steel sheet were fully joined by Al - Si eutectic phase engendered by eutectic reaction between the interlayer Si and base Al. The CRB process was divided four part: solid state diffusion, reaction generation of liquid, expanding of liquid and homogenization of liquid. The diffusion of Si during heating was really a kind of diffusion lapse of interlayer, which related to heating rate. The reaction generation of liquid was time-consuming because it was subject to the solid-state diffusion rate of Si into Al. The expanding and homogenization of liquid were controlled by the diffusion of Al into Al - Si liquid, so there were lots of liquid produced in these two stages. Rely on the preventative and retardant effect of the reaction liquid between the brazing paste and the base, the Al13Fe4、AlFe、AlFe3fragile compounds between aluminum and stainless steel were restrained, which result in thinner reaction layer Al13Fe4and more big strength of the joint.