Obtainment of the alumina polyamide-coated spherical particles

Abstract

The indirect selective laser sintering (SLS) process consists of a powder-based additive manufacturing (AM) technique. Recently, an attempt was carried out using the indirect-SLS method on ceramics to obtain complex geometric parts without the need to fabricate tools or molds. In this context, the ceramic particles employed in indirect-SLS must be coated with a polymer layer and retain spherical format. Currently, several processes of encapsulation and balling up of ceramic particles are available, among which thermally induced phase separation (TIPS) is noteworthy. The present study describes the synthesis, via TIPS, of spherical micrometric alumina particles coated with polyamide 12 to be employed in indirect-SLS. Dimethyl sulfoxide (DMSO) was used as a solvent to obtain these particles. After encapsulation, the agglomerates were characterized according to granulometry, microstructure, thermal behavior, and flowability. The obtained results delineated the ideal conditions to synthesize agglomerates with adequate flowability, particle size profile, and similar thermal behavior to that verified for PA-12, a currently used material in SLS printing. Based on the results of the present study, it is possible to confirm the effectiveness of the TIPS technique in obtaining ceramic polymer-coated spherical particles that are suitable for use in AM processes via indirect-SLS.