Inspired Square Micro-Texture Structures Designed by Nanosecond Laser Sculpture for Enhancing Adhesion Strength of Plasma Spraying Si-Hfo2 Bond Coat on Sic Substrates

Abstract

The laser surface texture (LST) SiC substrates with square micro-textures inspired by straw checkered sand fixation are fabricated using nanosecond laser sculpture. The Si-HfO2 bond coat is prepared using atmospheric plasma spraying. The adhesion strength of the LST sample is up to 27.31±3.34 MPa, which is more than 200% higher than the conventional grit-blasted one (8.12±0.70 MPa). The promoted interface bonding is attributed to the following three aspects: First, the mechanical anchoring established by micro-texture positively improves the adhesion strength. Second, the LST diminishes the contact angle to 16.5±1.7°, improving the wetting of the SiC substrate. Third, the high-pressure plasma is implemented to produce enormous compressive stress (205.6±14.6 MPa) on the SiC substrate surface, greatly aiding substrate/coating adhesion. The above three mechanisms work synergistically to enable the LST treatment to exhibit better adhesion than the conventional grit-blasted treatment on SiC substrate.

Keywords: Laser surface texture, mechanical anchoring, residual stress, adhesion strength