Existing selective laser sintering (SLS) processes for rapid prototyping are based on the sintering of loosely laid powders using an Nd-YAG (1.06μm wavelength) or a CO2 laser (10.6μm wavelength). High proportions of porosity and part shrinkage are the typical features of the green part produced. This paper reports on the characteristics of liquid phase sintering of a compacted metallic powder blend (50Cu/50Sn with 5% ZnCl2 flux) using a 60W (CW) diode laser of 810nm±2nm wavelength. By mechanically compacting the metallic powders layer by layer, porosity and surface roughness of the green part were reduced. Up to 100% increase in green density was achieved. Part shrinkage was avoided. In addition, layer thickness was reduced to 0.2mm. The effects of laser processing parameters (power, scan speed and line spacing) on sintering depth, surface roughness, Vickers hardness and microstructure characteristics are described. Also the effects of particle geometry and powder mixing ratio are reported.

Topics
Laser materials processing, 3D printing, Sintering
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© 1998 Laser Institute of America.
1998
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