Effect of Paste Flux Concentration on Adhesion Behavior

Abstract

In view of the problem that paste flux is difficult to spread uniformly on the surface of filler metal, the adhesion behavior of the different concentrations of paste flux on the surface of filler metal was studied by the equipment of OM, wetting angle tester and surface tensiometer. The results show that adhesive layer is gradually thickened with the increase of the concentration of paste flux. A small amount of shrinkage appears in the thin adhesive layer. however, mass paste flux slides off filler metal when adhesive layer is thicker, accompanying by severe aggregation and shrinkage. For the ideal surface, the adhesive tension of paste flux with different concentrations of paste flux is the same. For the actual surface, the stripe groove additional pressure is formed when paste flux wets stripe groove, and the additional pressure is the main reason for the lagging phenomenon of the shrinkage of the adhesive layer. With the increase of paste flux concentration, the additional pressure decreases, the hysteresis resistance decreases, and the shrinkage increases. A relationship is satisfied when the shrinkage takes place in thin adhesive layer, this is ΔWC ≥ A+ΔP. Whether the shrinkage occurs mainly depends on the adhesion tension and the additional pressure.

Keywords

• flux
• surface tension
• cohesion force
• apparent contact angle