Preparation of polyamide 6 and its titanium dioxide photocatalytic composite powders for laser powder bed fusion

Abstract

Laser powder bed fusion (LPBF) additive manufacturing is an effective method to prepare three-dimensional ordered network titanium dioxide (TiO2) photocatalytic materials, therefore enhancing the absorption intensity of incident light and improving the photocatalytic efficiency. However, TiO2 is difficult to be directly sintered by LPBF due to the high melting point and brittleness. In this study, we prepared a polyamide 6 (PA6)-coated TiO2 photocatalytic composite powder for LPBF based on the dissolution precipitation polymer coating (DPPC) method and evaluated its LPBF processability. In the precipitation process of PA6, there was a significant crystallization exotherm with temperature recovery. Effective temperature control of this precipitation process had a significant effect on the morphology and particle size distribution of the precipitated powder. The increase of the dissolved concentration of PA6 to 150 g/L produced an obvious temperature gradient of the reactor, resulting in a wide particle size distribution and a powder with a characteristic porous surface. The prepared PA6/TiO2 composite powder presents a near-spherical porous-surfaced morphology, a high specific surface area of 240.5 m2/kg, an appropriate Dv(50) of 48.8 μm, and a wide sintering window of 26.6°C, indicating a good LPBF processability and potential of the photocatalytic application.