Abnormal wetting behavior transformation in RB-SiC composite induced by laser irradiation and annealing treatment

Multifunctional reaction-bonded silicon carbide (RB-SiC) surfaces with tailored wetting behaviors have garnered notable interest due to their potential applications across various fields. However, the inherent hard-brittle nature of RB-SiC ceramics poses substantial challenges for the facile and controllable preparation of homogeneous and heterogeneous wetting surfaces via conventional techniques. Herein, taking advantage of the fact that laser irradiation of RB-SiC can induce the formation of SiO₂ phase and that SiO₂ with high surface energy can inhibit the adsorption of organic matter, the surface wetting characteristics of RB-SiC ceramics are flexibly tuned through a hybrid processing technique combining laser irradiation and annealing treatment. The SiO₂ content of the laser-irradiated surface can be regulated by varying the laser processing parameters. In the subsequent annealing process, the laser-irradiated surface with low SiO₂ content achieves a wettability transition from superhydrophilicity to superhydrophobicity, whereas the laser-irradiated surface with high SiO₂ content remains superhydrophilic. Inspired by annealing-induced significant difference in wettability, gradient wetting and extreme wettability contrast surfaces are prepared, enabling the directional transport of droplets. The homogeneous superhydrophobic surfaces produced at different annealing temperatures exhibit distinct anti-icing capabilities and adhesion properties. Importantly, the prepared superhydrophobic surfaces with varying adhesion forces can achieve no-loss droplet transport. This study provides a straightforward, high-efficient, and low-cost method for fabricating RB-SiC surfaces with diverse wetting behaviors, thereby promising to expand their utility spectrum and practical applicability.