Effect of gap filler on microstructure of wide gap brazing seam

The influence of gap filler on the microstructure of the brazing seam, especially of boride phase in the brazing seam, was investigated. The role of gap filler in the process of brazing and the methods of filling it in the brazing seam are discussed. It is shown that with gap filler the amount of eutectic and intermetallic compound in the wide gap brazing seam decreased, improving the microstructure. Different methods of gap filling in the brazing seam had different effects on the microstructure of the brazing seam. Of the three methods of filling the gap (mixture, preplacement, presintering), prelacing the presintered gap filler in the brazing seam resulted in the best microstructure. The size of the gap filler also had an effect on the microstructure of the brazing seam.