Effects of nano-ZrSi2 on thermal stability of phenolic resin and thermal reusability of quartz–phenolic composites

In this article, nano-ZrSi 2 -modified phenolic (Ph) resin and nano-ZrSi 2 -modified quartz–phenolic (Q–Ph) composites are, respectively, prepared by resin casting and compression molding. The effect of nano-ZrSi 2 on the thermal stability of Ph resin and the role of nano-ZrSi 2 on the thermal reusability of Q–Ph composites are investigated by multiple thermal gravimetric analyses and mechanical tests. The strengthening mechanism of nano-ZrSi 2 modification is investigated by the evolution of microstructure. The results show that the addition of nano-ZrSi 2 enhances the thermal stability of Ph resin under repeated heating at 1,200°C in air. The enhancement in thermal stability of resin exhibits a positive effect on improving the thermal reusability of composites. Within the range of 20 repeated heating times, the flexural strength of nano-ZrSi 2 -modified composites is above 16.01 MPa, which is 163.8% higher than that of unmodified composites. The strengthening mechanism of nano-ZrSi 2 is mainly in the inhibition of thermal oxidation and the reduction of microstructural defects during the repeated thermal environment.