Wettability enhancement of Al-Si brazing filler on stainless steel using plasma Al ion implantation

MEVVA ion source was used to implant Al directly into stainless steel to improve the wettability of the filler metal. The surface chemical composition of the implanted layer was characterized by X-ray photoelectron spectroscopy(XPS). The wettability of BAl88Si on stainless steels was investigated by metallographic microscope and scanning electron microscope(SEM). Aluminum was observed within the top surface of stainless steel after ion implantation. BAl88Si did not wet on unmodified stainless steel at 600℃ and 610℃. If the temperature was elevated to 650℃,the BAl88Si solder demonstrated some wettability on unmodified stainless steel with the wetting angle of over 40°. Al ion implantation plays an important role on the improvement of wettability. With implantation dose of 9×10¹⁷ ions/cm² and the extraction voltage of 40 kV,BAl88Si exhibits good wettability on implanted samples,even at 600℃. A wetting angle of about 20° was achieved and satisfied the brazing demand of aluminum onto stainless steel.