LCVD repair of step surfaces with various rotation angles in additively manufactured SiC ceramics: nanomechanics and interfacial bonding

During laser powder bed fusion (LPBF) of complex structures, different inclined angles are unavoidable to form the curved surfaces or overhangs, which results in step textures and degraded surface performance. Therefore, this study proposes an innovative method based on laser chemical vapor deposition (LCVD) that achieves effective filling of the step gaps in the LPBF-fabricated silicon carbide (SiC) substrates. The effects of deposition temperature and substrate rotation angles on coating morphology, mechanical properties and bonding strength are studied in depth. With the increase of deposition temperature, grains in the step grooves grow faster and the grain size becomes more uniform. As the rotation angle increases, the step gaps decrease, which promotes grain merging to fill the gaps and the growth of (111)-oriented grains. The nanomechanical properties are significantly enhanced, with an elastic modulus of 404 GPa and a hardness of 48.7 GPa. In addition, the critical interfacial adhesion increases from 19.4 N for the 0° substrate to 27.4 N for the 90° substrate, indicating a 41% enhancement with increasing surface step orientation. This study provides a practical solution for improving surface quality in additively manufactured SiC components for high-end applications.