EFFECT OF TEMPERATURE ON THE TENSILE BEHAVIOUR OF A CAS/SiC CMC

摘要

A set of low strain rate tensile tests have been carried out on test pieces of a continuous fibre ceramic matrix composite (C AS/SiC) at temperatures ranging from room temperature to 900°C. A correlation is established between the more significant tensile properties and the deformation and fracture mechanisms observed in these high temperature tests. A substantial decrease of the fracture stress is observed at 700°C and 900°C. However, up to 500°C, the mechanical behaviour is similar to that observed at room temperature. On the other hand, the fracture strain and strain energy density have a maximum at 500°C. This behaviour is explained as the combined action of two processes: oxidation of the Nicalon fibres and the carbon interface and residual stress relaxation, both induced by the temperature increment.