Processing and characterization of lithium aluminosilicate glass parts fabricated by selective laser melting

Abstract

This thesis investigates the densification mechanism and phase transformation occurring during selective laser melting of lithium aluminosilicate glass powder. The particle size, laser power and scan speed were varied to study the densification process. Continuous scan tracks can only be formed when there is complete melting of the powder bed. This requires the use of a small particle size and a slow laser scan speed. However, this results in vapourization of material under the laser, with melting caused by the heat-affected zone (HAZ). Single layer coupons show that good bonding is possible between the scan tracks. When fabricating a bulk part, the densification regime changes from viscous coalescence to total melting of the powder particles as the laser intensity increases. The bulk parts fabricated at lower laser intensities are amorphous, while those fabricated at higher laser intensities are crystalline. Exposure of the glass to intense laser irradiation results in loss of ions from the glass structure.