Effect of oxygen content on wettability and mechanical property of brazing seam for silver based powdered brazing filler metal

The properties of silver brazing filler metal with different oxygen content were studied by optical microscope, scanning electron microscopy and other analytical tools. The results of the experiment indicate that with the increase of oxygen content,the melting point of the solder alloy rises,which is 56℃ higher than that is casted when oxygen content is 0.6047%. With increase of the oxygen content,the surface layer of the brazing filler metal was covered with much oxide,the wetting ability between the solder and the substrate significantly decreases. When the oxygen content is about 0.02%,the tensile strength of the brazing filler metal is lowered slightly. When the oxygen content increases to more than 0.03%,the tensile strength decreases from over 300 MPa to about 170 MPa. The size of the inclusions in the welded joint increases with the oxygen content increases, while the brazed rate decreases.