Flame-retardant aramid felt-reinforced phenolic coatings for carbon fiber-reinforced polymers (CFRPs)

For over fifty years since carbon fiber-reinforced polymers (CFRPs) were introduced to the automotive industry, enhancing their flame-retardant properties has been studied due to their vulnerability to fire. Coating is one method of flame-retardant enhancement, accomplished by modifying surface characteristic to achieve its goal. Phenolic resin-based coatings, as a candidate material, offer advantages such as good chemical compatibility and cost efficiency. However, to meet the necessary specifications for flame-retardant performance, a thick coating layer with higher brittleness is required. In this study, we developed an aramid felt-reinforced coating layer to address the limitations of phenolic coatings. The effectiveness of the flame-retardant coating was demonstrated through various tests, including limiting oxygen index (LOI), micro-combustion calorimetry, heat exposure test with cone shaped heater, and mechanical property tests including surface-burning test. Consequently, the aramid felt-reinforced phenolic coating exhibited superior flame-retardant enhancement using a cost-effective, easy-to-follow, and lightweight method, achieved with a relatively thin coating fabrication.