Polydicyclopentadiene (PDCPD) was prepared in a simulating reaction injection molding system. Dry friction behaviors of the PDCPD under elevated sliding velocity (5m/s, 10m/s, 15m/s, and 20m/s) against GCr15steel were investigated on a high-speed pin-on-disc tribometer. Their microstructure changes on sliding surface were examined by using scanning electron microscopy (SEM). The results showed that the wear mass loss of PDCPD increased with the increase of sliding velocities. The friction coefficients of PDCPD under a sliding velocity of 5m/s were the most stable, and the friction coefficients were irregular with the further increasing the velocity. The results of SEM analysis showed that the wear mode is typical abrasive wear at a sliding velocity of 5m/s and the wear mode had transformed into typical adhesive wear at a velocity of 20m/s

The compression test of self-healing SiC/SiC was carried out, and acoustic emission (AE) signals were simultaneously collected. Using the AE signal pattern recognition and the sentry function based on AE, the mechanical property and damage evolution process were studied. Combined with the SEM observation of the fracture surface, four damage modes, namely, matrix cracking, interface debonding, interface friction, and fiber shear breakage, were identified, and their typical AE characteristics were obtained. According to the pattern recognition result and the trend of the sentry function, it is found that although the loading curve is approximately linear, the failure process can actually be divided into four stages. The sentry function provides an early warning before the catastrophic failure of SiC/SiC. The ultimate strength, lower than the maximum stress, can be defined from the damage evolution identified by AE.