Study on self-heating metallic powder for the selective laser sintering process

Abstract

Fabricating metallic functional parts directly using the selective laser sintering (SLS) process is a promising technique which is engaging many researchers. Existing problems during direct fabrication of a metallic part using SLS are analysed. To solve the problems, a new self-heating metallic powder material for SLS direct rapid fabrication is developed. This new material can release a controllable amount of heat during its interaction with laser beam energy, resulting in a reduction of the requirement to use laser power during direct sintering of the metallic part, prolonging the time in the metallic liquid phase and improving the strength and precision of the SLS part. A self-propagating high-temperature synthesis (SHS) material is selected as a self-heating component. For this reason, interaction of the SHS material with CO2 laser beam energy is researched, which proves that CO2 laser beam energy can instantly ignite the SHS reaction. On the basis of these investigations, the effect of sintering the metallic powder material mixed with SHS material using a CO2 laser is also researched. The results show that there is an optimal blending ratio of various materials in the new metallic powder material. Under the optimal blending ratio and SLS process parameters, this new metallic powder material can release a large amount of heat and the SHS reaction can be controlled within the laser sintering. This work shows that it is possible for the metallic part to be directly sintered using a small CO2 laser power (less than 50 W), thus greatly reducing the dimensions, price and running expenditure of an SLS machine and making it suitable for many applications.