Design and optimization of oxidation resistant coating for C/C aircraft brake materials

Abstract A SiCN/borosilicate glass anti-oxidation coating with double-layer structure was designed for C/C aircraft brake materials. The SiCN layer was introduced as transition layer to improve the wettability between borosilicate glass and C/C composites, and the microstructure results indicated that the coating with SiCN inner layer was dense and uniform. The oxidation resistance evaluation of the coated samples was conducted at 800 °C in air for 10 h. The weight loss of SiCN/borosilicate glass coated samples valued ~ 5.66% indicated that the oxidation resistant property of the simple SiCN/borosilicate glass coating was not good, which was mainly due to the relative large viscosity of borosilicate glass at 800 °C. B 4 C was introduced to add into the outer glass coating to improve the self-healing ability of the coating. After oxidized at 800 °C in air for 10 h, the weight loss of the SiCN/borosilicate glass-B 4 C coated samples was ~ 2.48%. B 4 C could consume the oxygen diffused into the coating and the reacted product B 2 O 3 with a better fluidity at 800 °C could effectively heal cracks and pores in the coating to improve the oxidation resistance property. The reaction of B 4 C oxidized to B 2 O 3 was accompanied with ~ 1.5 times volume expansion, which was also beneficial for the healing of defects.