Effect of pre-treatment and annealing temperature on the strength of SiC-Ni monofilament composites

Abstract

Monofilament composites were prepared by plating nickel on Nicalon, a commercial SiC fibre obtained from a precursor of polycarbosilane. The surface condition of the fibre was controlled by pre-treatments prior to the nickel plating. The tensile strength of the monofilament composite decreased with increasing annealing temperature, especially above 973 K, where reaction between the fibre and nickel begins. The extent of degradation of the composite caused by the reaction was different for different pre-treatment and annealing temperatures. The degradation was explained by the Griffith theory. The calculated strength of annealed composites agreed fairly well with the measured values. SEM observations showed that the strength is closely related to the morphology of the reaction products.