The Technology And Performance Of Soldering Wire During Hot-dipping Aluminum

The main subject of this thesis tried to aluminize soldering wire during hot-dipping aluminum to replace the traditional copper wire. According to the flux method, the pretreated aluminum wire was immersed in molten liquid mainly. Fe-Al alloy layer formed by the diffusion reaction gave substrate metallurgical bonding to prepare aluminum wire.In this thesis, the process, structure and performance and formation mechanism of coating have been investigated. The effects of hot-dipping process parameter(such as temperature and time ) on the structure, thickness and morphology were studied by SEM and XRD, in order to analyze the growth kinetics of the coating. The experimental results showed that, the coating composed of outer Al layer and inner alloy layer ,which was metallurgical bonded with substrate, and the alloy layer consisted major Fe₂Al₅ and minor FeAl₃, from outer to inner .The thickness of coating increased by dipping time's and temperature increasing. Aluminum layer was mainly affected by temperature and its thickness decreased with temperature's increasing. Micro-hardness test results showed that, the surface layer hardness reached to 100²00 HV while the alloy layer hardness reached to 500⁶00 HV, and was more brittle.Also the corrosion resistance of aluminized wire was studied using three-electrode system by measuring polarization curves and electrochemical impedance spectroscopy. The open potential and current of aluminized wire and copperized wire were significantly decreased, and open current of aluminized wire was the minimum of three. EIS of aluminized wire in 0.5mol/L NaCl environment showed double capacitance arcs. Polarization curves and EIS results completely proved, under the same conditions, aluminized wire can replace the traditional copper wire to protect the substrate. The resistance of aluminized wire was much better than traditional copperized wire.