Effect of B4C addition on the oxidation behavior of borosilicate glass repairing coating for C/C brake materials

The thermal properties of the borosilicate glass repair coating with B4C as a ceramic additive were analyzed, and the changes of thermal expansion, density, and porosity of the glass materials were investigated to characterize the physical characteristics of the repair coating. The results showed that this repair coating displayed variable oxidation resistance and self-healing property at temperatures from 700 to 900 °C, depending on the B4C content. The B2O3 generated from B4C can be dissolved into the borosilicate glass, which could significantly change the coefficient of thermal expansion and the softening temperature of the glass. When B4C content was 25 wt%, the coating with the lowest porosity and oxygen permeability was formed. A model of structure transition of the oxidation-resistant mechanism of the B4C added borosilicate glass coating was discussed.