Structure and properties of fine diameter continuous SiC ceramic fiber reinforced Al matrix composites

The polymer-derived-SiC ceramic fibers reinforced 7075 aluminum alloy composites were prepared by hot pressing method. The effect of an in-situ carbon coating on the fiber surface was investigated. The results showed that the uncoated SiC fibers reacted with the Al matrix after hot pressing at 630 °C for 6h. The interfacial bonding was too strong to deflect micro-cracks, leading to a pseudo-brittle fracture with a flexural strength of only 170.7 MPa. When an in-situ carbon coating of 400 nm was prepared on each SiC fiber, the carbon coating reacted with the Al matrix instead of the SiC fiber to form a complex multi-layer interface of 160 nm. The composite had an enhanced strength of 879 MPa. When heat treatment in air, the interfacial bonding strength of the two composites both gradually decreased, making the fracture mode and mechanical properties change finally.