Investigation of SiC decomposition in laser powder bed fusion: impact of scanning strategies

Abstract SiC is susceptible to decomposition into Silicon and Carbon during. D-LPBF when exposed to temperatures above its decomposition threshold. This study investigates the impact of various laser scanning strategies; linear, concentric in-out, zigzag, and hexagonal patterns. The temperature history effects of these scanning strategies were investigated to observe the SiC degradation and its impact on the phase composition. A thermal simulation model was developed to analyse temperature evolution under each scanning pattern. Results showed that concentric in-out, zigzag, and hexagonal strategies involving frequent changes in laser direction generated localised high-temperature peaks. These peaks enhanced layer bonding but also triggered partial decomposition of SiC. However, the linear strategy lacked sufficient thermal peaks, resulting in poor interlayer adhesion and overlapping defects. Quantitative phase analysis was conducted using Rietveld refinement of X-ray diffraction (XRD) data. The hexagonal strategy resulted in the highest decomposition, yielding 18% Si and 5.66% C, while the zigzag strategy demonstrated the lowest decomposition, with 8.84% Si and 1.07% C. The study highlights the critical role of scanning strategy in balancing layer quality and decomposition, underscoring the need for optimised scanning patterns to mitigate degradation in LPBF of ceramics, such as SiC.