不锈钢表面电镀锡银钎料的润湿特性

Aiming at revealing the wetting characteristic of Sn-electroplated Ag brazing alloys on the surface of 304 stainless steel, wetting test furnace, imaging-type sintering point tester, scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectrometer (EDS) were applied to analyze the wetting behavior, dynamic spreading process, interfacial microstructure, phase composition and element distribution. And the chemical elements of the interface was analyzed by line scan. The results suggested that the improved wettability of the Sn-electroplated Ag brazing alloy on stainless steel surface is intrinsically caused by the prior spreading of the wetting precursor, which is mainly induced by the B₂O₃ in FB102 flux employed during wetting experiment. Cu₄₁Sn₁₁ compound phase, which appears at the interface of Sn-electroplated Ag brazing alloys and stainless steel, is perpendicular to the wetting interface and grow inward the brazing seam form a "column" shape. With the increase of Sn content, the wetting area of Sn-electroplated Ag brazing alloys exhibited an expanding trend on the surface of stainless steel. Compared with the traditional brazing filler metals, under the same Sn content, the wetting area of Sn-electroplated Ag brazing alloys increased about 8.1%-12.5%. When Sn content is 7.2 wt%, the wetting area of Sn-electroplated Ag brazing alloys reached the maximum value of about 481 mm². Our research also implied the diffusion-compound-type bonding form of the interface between Sn-electroplated Ag brazing alloys and 304 stainless steel.