气相渗硅法修复 SiC 涂层及其抗热震和烧蚀性能

Integrity and denseness of coatings significantly influence their performance. Scrapping and re-preparation of defective or damaged coatings not only lead to material waste but also prolong preparation time. To address the challenge of cost-effectiveness, repairing the coating to restore its protective capability is obviously essential. However, there is rare literature touched effective repairing method for porous SiC ceramic coatings. In this study, a straightforward and cost-effective gaseous silicon infiltration method was employed to repair defects in porous SiC coating prepared by pack cementation. Comparison experiments on thermal shock and ablation resistance of the coating were carried out before and after repair. Results demonstrated that the repaired coating exhibited robust adhesion to its substrate after 15 thermal cycles from room temperature to 1773 K, with a mass loss rate reduction of 97.05% in contrast to the pack cementation SiC coating. After ablation for 30 s, carbon fibers located in the center area of the repaired coating were successfully coated with SiO₂, without naked exposure or damage. The mass and thickness loss rates were reduced by 97.02% and 67.99%, respectively. All above results indicated that thermal shock and ablation resistance of the repaired coating were enhanced, which can be attributed to the increased densification and the reduction of defects in the repaired coating. Therefore, silicon, introduced through gaseous silicon infiltration, is more easily oxidized at elevated temperature to form SiO₂, which effectively heals defects and obstructs oxygen penetration, thereby preventing further oxidative damage to the substrate. This study provides a novel coating repair strategy with good economy and feasibility, constructs a new approach to effectively repair defects and damages of coatings, and enhances their service stability and durability.