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

In order to enhance the adhesion strength between the Si-HfO2 bond coat and substrate, square micro-textures inspired by straw-checkered sand fixation are fabricated using nanosecond laser sculpture. The adhesion strength of the laser surface texture (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.