Low temperature mechanical behavior of 1D-Cf/SiO2 composite

Unidirectional carbon fiber reinforced fused silica (1D-Cf/SiO2) composite was prepared by slurry infiltration and hot-pressing. The flexural strength and the coefficient of thermal expansion (CTE) at room and liquid nitrogen temperature (77 K) were investigated. The flexural strength of the composite tested at 77 K was 878 MPa, higher than that 667 MPa at room temperature. Moreover, the CTE of the composite at 77 K was higher than that at room temperature. Due to the difference of CTE between the matrix and fiber, gaps appeared at the fiber/matrix interface of as-prepared specimens. However, they may be healed up because of the thermal expansion of carbon fiber at 77 K. It led to a higher interfacial sliding resistance and changed the weak fiber/matrix interfacial bonding. Thus, it was helpful for the load transfer from matrix to fiber.