Influence of ZrB2 Nanoparticles on the Mechanical and Thermal Behaviors of Carbon Nanotube Reinforced Resol Composite

•Ability to combine ZrB2 nanoparticles and multiwalled carbon nanotubes within resol resin•Use of ZrB2 particles at nanoscale dimensions•Dramatic improvement in the linear ablation rate of phenolic resin by 76% by adding these nanostructures•Dramatic improvement in the mass loss rates of phenolic resin by adding these nanostructures

The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes and zirconium diboride (ZrB2), were used in a new design of mixture to produce the heat-resistant ablative composite system. The CNT/ZrB2/carbon/phenolic nanocomposite (Z/NT-CR) system corresponding to CNT/carbon/phenolic nanocomposite (NT-CR) showed a reasonable decrease in mass loss and the ablation rate as compared to carbon/phenolic composite (CR). However, substantial drop in two factors was found for Z/NT-CR as compared to carbon/phenolic and NT-CR. Ablation mechanisms for all three composites were investigated by thermal gravimetric analysis in conjunction with microstructural studies using a field emission scanning electron microscope. The microstructural studies revealed that CNTs acted as an ablation resistant phase for protection against 2000 °C, and the conversion from ZrB2 to ZrO2 played an important role as an insulator in the performance of char layer in the ablation resistance.