Laser sintering of cold-pressed Cu powder without binder use

Abstract

In this work, laser sintering (LS) of cold-pressed copper (Cu) powder without using a binder was demonstrated. To promote the densification of the final part, the Cu powder was cold pressed beforehand, thereby forming a densely packed powder bed for the LS. The densification and microstructural evolution study show that the cold-pressed powder led to an increase of up to 11% in the relative density and a decrease of 10 times in the surface roughness. The influence of the scan speed on the densification and sintering quality was studied. A relatively slow scan speed, 25 µm/s, allowed sufficient atomic diffusion during the LS process and ultimately produced dense Cu parts without cracks and open pores. The introduction of the cold-pressing step into the LS process is critical for achieving high-density powder metallurgy parts without using binders.