Controllable Preparation and Forming Mechanism of Bamboo-Shaped SiC Nanowires Reinforced SiC Dense Coating

The bamboo-shaped SiC nanowires reinforced SiC dense coating (dense SiCNWbs/SiC coating) was successfully designed on the graphite by polymer pyrolysis chemical vapor deposition (PPCVD) combined with chemical vapor deposition (CVD) method. By analyzing the thermal decomposition of the mixed powder of PCS and activated carbon, it was determined that the porous bamboo-shaped SiC nanowires layer could be grown by the PPCVD technology based on a dual-temperature zone whose optimal temperatures were determined to be 800 celcius + 1200 celcius. SEM results showed that the porous layer prepared by the catalyst solution of 0.1 mol/L and holding time of 2 h was easier for the subsequent SiC densification. As expected, the dense SiCNWbs/SiC coating (SS1 coating) was successfully fabricated. Compared with the loose coating, the SS1 coating showed better performance. SS1 coating possessed better crystallinity. The bonding strength between the coating and the substrate was 11.96 MPa, and the weight loss was just 0.79% after oxidation at 1500 celcius for 60 h, which showed the potential of excellent anti-oxidation protection. Finally, the forming mechanism of the dense coating was revealed, which provided a theoretical basis for the forming and application of the dense anti-oxidation coating of C/C composites.