With the increasing demand for long-term oxidation resistance and reusable high-temperature materials in aerospace, SiC/SiC composites are becoming a research hotspot. This paper summarizes the progress in fatigue and creep properties of SiC/SiC composites in recent years, comprehensively analyzes the effects of temperature, load, frequency and gas environment on fatigue properties, as well as the effects of fiber type, temperature and load, frequency and matrix type on creep properties.

As one of the key performance indicators of composites, thermal shock performance may be related to sample size. In order to explore the thermal shock performance of SiC_f/SiC composites, high temperature water quenching experiments at 1,200℃ were conducted with SiC_f/SiC rectangle composite samples prepared by polymer infiltration pyrolysis (PIP) process. In addition, the above water quenching experiments were simulated by ABAQUS finite element software. In this study, three samples (i.e., S4, S8, S12) from SiC_f/SiC composites with bending strength and interlaminar tensile strength of 553 MPa and 19.2 MPa, respectively were taken as the subjects of water quenching experiments. During the water quenching experiments, the samples started to form microcracks after 3 cycles, which expanded with the increase of the number of cycles. After 8 cycles, matrix cracks started to appear in S8 and S12 while a crack was observed extending along the 0° fiber direction in 5/6 layer at one end of S12. According to the finite element analysis results, the cracks in the 6/7 layers of S4 and S8 were firstly cracked and then closed, which might be due to space occupation of the secondary cracks caused by main cracks's propagation. The outcomes of stress calculation demonstrated that the thermal stress of the samples in this study increased with the increase of sample size due to the temperature gradient. The thermal stresses in S8 and S12 reached 40 MPa, resulting matrix cracks and extension.

The poor toughness of liquid molding bismaleimide resin (BMI) had hampered its application in the aeronautics and space field before core-shell particles with double-layer structure were introduced to toughen BMI. The fracture morphology of BMI was studied by scanning electron microscopy (SEM) showing that the fracture surfaces of the toughened BMI were ductile fracture morphology owing to crack propagation blocked. In addition, the content of core-shell particles was adjusted to perfectly improve the comprehensive performance of BMI. Compared to the neat BMI, toughened BMI exhibits excellent mechanical performance with a tensile strength of 108.8 MPa, increased by 13.1%, an elongation at break of 3.12%, increased by 16.8%, a flexural strength of 190 MPa, increased by 12.4%, a K_Ic of 2.83 MPa/m^1/2, increased by 20.9%, and a G_Ic of 1619 J/m², increased by 54.6%. Moreover, the toughened BMI can maintain heat resistance and thermal stability, with glass transition temperature of 292.3°C and 5% weight loss temperature of 401.0°C.

To explore the application universality and prospect of carbon nanotube film (CNTF) in curing of resin-matrix composites via resistance heating, CCF800H/EC120A carbon fiber reinforced resin matrix composites were treated by CNTF electric heating cure. To optimize the electrothermal curing process, effects of electricthermal cure processes assisted with vacuum and with press mould on internal quality, glass transition temperature, mechanical properties and microstructure of composites were compared, thus identifying the roles of vacuum degree and external pressure in the electrothermal curing process. The results show that the CNTF can achieve rapid and uniform heating. Compared with press-moulded composite laminates cured by CNTF, composite laminates cured by CNTF within vacuum sealed bag own better internal quality, higher Tg and higher mechanical property, indicating that during the cure process of such prepreg, vacuum degree plays a more significant role than the external pressure in controlling internal quality and performance of obtained laminates. Bending strength of laminates cured by CNTF within vacuum sealed bag maintains at 90% of that cured by traditional oven cure，bending moduli of both cure methods are similar and laminar shear properties also show minor differences.

The curing process and cure kinetics of a high-temperature cured adhesive foam have been investigated by dynamic differential scanning calorimetry (DSC) experiments. In the DSC measurements，heating rates of 1, 2.718, 7.389 and 20 K·min^-1 were used such that lnβ would be 0, 1, 2 and 3, therefore, values of T₁ and ΔT could be easily and quickly determined so as to estimate the apparent activation energy more easily. Linear relationships have been proven to frequently exist between T_p with lnβ by means of a series of reference data from papers about heating cure, thermal decomposition and crystallization of some polymers. The obtained linear equation of T_p versus lnβ can be used to explain some laws for higher or lower of apparent activation energies (E_a), and the apparent activation energy (E_a) can be quickly determined.

With the application of composites in the main load-bearing structure, composite repair technology has become an important part of the service life of composites. The riveting repair method has an important application in rapid repair technology. In this study damage of carbon fiber composite materials was simulated by the central digging runway-shaped hole method, then the stainless steel plate and titanium alloy plate were used to rivet the damaged parts of the composites. The axial tensile tests of the damaged specimen and the two repair parts were carried out, in which a strain gauge was used to monitor the strains of the hole edge and the metal plate center. The test results show that the maximum loads of the repaired parts obtained by riveting the damaged parts of stainless steel, titanium alloy, and composite are the same, which are increased by 65.2% the unrepaired specimen, indicating that the use of metal materials riveting repair has a certain enhancement effect on the bearing capacity of the damaged composite plates and that the repair effects of stainless steel and titanium alloy materials are comparable. In the tensiling process of the repair specimen, the carbon fiber reinforced composite fails before the metal material; the failure strains of the two metal riveted repair parts are only slightly increased as compared to those of the unrepaired ones.