Fusion behavior of TrueForm TM/SiO 2 composite powders during selective laser sintering

Abstract

Purpose - This paper aims to study the effects of solid additives and compounding processes on the selective laser sintering (SLS) behavior of composite powders. Design/methodology/approach - Composite powders were prepared from TrueForm™ acrylic-styrene co-polymer and SiO 2 powder. Dry mixing and melt extrusion were used as the blending processes to produce the composite powders. Some SiO 2 powder was ground and treated with silane coupling agent before blending to study the effects of particle size and surface treatment of the filler, respectively. The temperature of the powder bed was monitored using an infrared thermometer. The fusion behaviors of the powders were investigated in situ using an optical microscope and the sintered specimens were examined by scanning electron microscopy. Findings - For a given volume fraction of the filler, reducing its particle size will hinder fusion between the polymer particles and weaken the sintered specimens. Surface treatment of the filler by silane coupling agent had little effect on the morphology of the sintered specimens; however, it slightly improved their strength. The blending method plays an important role in the sintering behavior of the composite powders. Although melt blending improved the polymer-to-polymer contact between the composite powder particles, the high-resultant viscosity of the material adversely affected the densification of the powder bed, leading to a highly porous structure of the sintered specimens. Research limitations/implications - The sintering experiments were conducted in ambient conditions using a laser engraving machine instead of a commercial SLS machine with atmospheric control. The temperature gradient within the powder bed was expected to be higher than that in normal SLS processes. Practical implications - The SLS behavior of a composite powder not only depends on its composition but also on the powder preparation method or powder morphology. Originality/value - This paper provides some useful information for future development of composite powders for SLS applications. © Emerald Group Publishing Limited.