Effect of braze flux on direct laser sintering Cu-based metal powder

Influence of braze flux on the wettability and densification in direct laser sintering Cu-based metallic powder has been investigated. The 0.3 ∼ 3 wt% braze flux mainly consisting of KF (Potassium Fluoride) was added as an additive in the Cu-based metallic powder. The addition of the braze flux has dramatically improved the wettability and hence the density of the sintered samples. It has demonstrated that a small amount of flux increases the densification and sinterability while a large amount of flux additive shows negative effect in densification and sinterability. The relative density of the sample with 0.3 wt% braze flux additive increased about 7.1% compared to that of the sample without additive. Balling phenomenon was observed when higher percentage flux (1.2, 3 wt%) was used. However, the additive might cause residues covering on the surface leading to a deterioration of adhesion between the sintering layers.