Effect Of Adding Ag Or Cu On Properties Of Zn-Al Brazing Filler Metal

Effect of adding Ag or Cu on the microstructure of Zn-Al brazing filler metal,melting temperature, spread ability, corrosion resistance and the mechanical propertyof brazed joint were studied respectively. Meanwhile effect of adding rare earthelement La and Ce on the microstructure of85Zn15Al5.6Cu brazing filler metal,melting temperature, spread ability and corrosion resistance were studied respectively.Results show that with the addition of Ag in85Zn15Al brazing filler metal, themicrostructure is improved significantly, the melting temperature increase slightly, thespread ability and the mechanical property of the brazed joint are improved, andcorrosion resistance performance are enhanced. When the Ag content is up to3.5%,the filler metal shows the best spread ability. If continue to increase the Ag content,the spreading area will remain stable. The mechanical property of the brazed joint isaffected by solid solubility of the Ag. When the Ag content is up to3.5%, the fillermetal shows the best mechanical property of the brazed joint. With the addition of Cuin85Zn15Al brazing filler metal, the microstructure is improved significantly, themelting temperature decrease slightly, the spread ability and the mechanical propertyof the brazed joint are improved, and corrosion resistance performance are enhanced.The spreading area is affected by the solubility of Cu in Al, when the Cu content isbelow its solubility in Al, with the increase of Cu content, the spreading area increases.When the Cu content is up to5.6%, the filler metal shows the best spread ability. Ifcontinue to increase the Cu content, the spreading area will remain stable. Themechanical property of the brazed joint is affected by the diffusion of the CuAl2phase.When the Cu content is up to5.6%, the addition of Cu can refine the CuAl2phase, thefiller metal shows the best mechanical property of the brazed joint. With the additionof rare earth element La and Ce in85Zn15Al5.6Cu brazing filler metal, themicrostructure is improved significantly, the melting temperature almost remain thesame, corrosion resistance performance are enhanced. When the rare earth element isup to0.3%, the filler metal shows the biggest spreading area.