Effect of brazing material pretreatment and sintering atmosphere on sinter-brazing of iron based powder metallurgy parts

The iron-based powder metallurgy materials were sintered and brazed with the water atomized Ancorbraze 72 (AB72) powders. The wettability and penetration depth of the brazing materials were studied by brazing material pretreatment and changing sintering atmosphere. The results show that, with the increase of pretreatment temperature, the maximum diameter of brazing residue on the matrix surface decreases obviously, and the diffusion range of brazing material at 1000 μm away from the wetting surface decreases gradually. When the pretreatment temperature is 800 ℃, the brazing residue is the least, the diffusion range is the least at 1000 μm away from the wetting surface, and the pretreatment effect is the best. When the pretreatment temperature is 800 ℃, the treatment time is 2 h, and the treatment atmosphere is 75%N₂+25%H₂ (volume fraction), the residue on the brazing surface is less, and the diffusion range of the brazing materials is the smallest at 1000 μm away from the wetting surface. A certain amount of endothermic atmosphere during the sintering brazing can obviously improve the penetration of brazing materials in the matrix. When the flow rate of endothermic atmosphere is 20 m³∙h⁻¹, the improvement of wetting angle and penetration depth is the best.