Interfacial microstructure and strengthening mechanisms of LCVD coatings on surface patterned LPBF SiC ceramics

Laser powder bed fusion (LPBF) fabricated silicon carbide (SiC) has great potential for optical mirrors and semiconductor equipment because of its advantages in lightweight design and complex geometry fabrication. However, the resulting substrates still suffer from insufficient densification, limited purity, and poor surface quality. Dense SiC coatings are therefore usually deposited to form a functional surface layer, and the strong interfacial adhesion is essential for reliable service. To address this issue, this study innovatively proposes a surface patterning strategy for additively manufactured SiC substrates. Groove patterns were introduced onto the substrates, and the effects of groove width and spacing on coating adhesion strength, nanomechanical properties, crystallographic orientation, and interfacial fracture behavior were systematically investigated. The results show that decreasing groove width improves both coating adhesion strength and nanomechanical properties, while adhesion strength first increases and then decreases with increasing spacing. The sample with a groove width of 0.4 mm and a spacing of 1.5 mm achieved the highest adhesion strength of 20.7 MPa, which is 4.3 times that of the non-patterned substrate. Its nanomechanical properties were also significantly improved. The groove patterns favored V-shaped coating growth with preferred (111) orientation, whereas the patterned interface induced crack deflection during fracture. These combined effects contributed to the enhanced interfacial adhesion. This study provides a practical and effective strategy for improving coating adhesion in high performance SiC components.