The Research Of Zn-Al Flux Core Wire

This paper designs five different composition kinds of Zn-Al flux cored wire. Using EDS to determine the actual composition of brazing filler metal, using DTA to study the melting characteristics of brazing filler metal; using both furnace brazing and flame brazing methods to braze the Al/Cu joints, studied the effects of solder composition and processing factors to the wettability of solder、shearing strength and decay resistance of joints, it provides experimental and theoretical basis for optimizing the composition and process of Zn-Al flux cored wire.The composition of Zn-Al solder has an obvious effect on the manufacture of Zn-Al flux cored wire. The brazing filler metals of Zn72A128and Zn80A120have bad production process, but the Zn-Al flux cored wire which made by Zn80A115Ag5、Zn92A18and Zn95A15has better quality.Five kinds of Zn-Al flux cored wire have good spreadability in6063aluminum alloy; The contents of aluminum element in Zn-Al flux cored wire has great effect on the spreadability in copper, with the increase of aluminum in the solder, the solder’s spreading areas in the copper will increase rapidly. Zn72A128can get the largest spreading areas in the copper which can be up to86mm2.The shear strength of the Al/Cu joint which brazed by Zn-Al flux cored wire will increased in the first and then drop with the increase of Al, the strength of Zn80A120flux cored wire is highest (flame brazing81MPa, furnace brazing62MPa); To the different composition of the Zn-Al flux cored wire, the shear strength of Al/Cu joint which brazed by flame brazing is higher than the furnace brazing, duing to rapidly heating ways of flame brazing, which makes joint’s organization become tinier and denser than the furnace brazing, and rapidly heating can lighten the corrosion effect of base metal’s caused by Zn-Al brazing filler metal; Al/Cu joint brazed by Zn-Al flux cored wire always cracked in interface between brazing seam and copper base metal, so the interface between brazing seam and copper base metal is the most fragile area in the Al/Cu joint; In the Zn-Al flux cored wire,when Al content is low, the interface organizations between brazing seam and copper base metal will present layer structure;With the increase of Al element, the interface organizations is from layer structure to Bamboo shoots structure. The compositions of Zn-Al flux cored wire have a great influence on the corrosion resistance of the Al/Cu joint. With the decrease of Al element, the joint’s corrosion resistance becomes bad. Corrosion tests shows that the joint which brazed by Zn72A128flux cored wire has the best corrosion resistant, and its strength loss rate is the lowest that is probably10%. Brazing process methods also have effects on the corrosion resistance of Al/Cu joints. The corrosion resistance of Al/Cu joints which is using flame brazing with Zn-Al flux cored wire is better than the furnace brazing’s.Summarized the manufacturing process、the brazing Al/Cu joint nature、the strength of the joint and the corrosion resistance of the five Zn-Al flux cored wire, using the Zn80A115Ag5flux cored wire which added Ag elements has the best comprehensive property when brazing Al/Cu joint.