Heat durability of carbon fiber reinforced nickel composites

Carbon fiber is a highly heat resistive material in an oxygen free atmosphere. Nickel is also a heat resistive metal and an important element for a superalloy. We can expect an excellent heat durable composite when they are combined. Nickel was electroplated on a carbon yarn to form a monofilament composite. When the high strength fiber was tested, the composite started to lose its strength at 600°C. The deterioration was caused by graphitization of the carbon in the fiber. This is caused by the difference of the graphitization degree between crystallites in a fiber. A high modulus carbon fiber has little difference of the graphitization degree in a fiber. The high modulus fiber did not react when tested and the fiber strength was maintained after heat treatment at 1100°C for 9 h. From the results, the high modulus carbon fiber composite is promising to be durable at a high temperature.