Experimental and numerical investigation on SiC coating delamination from C/SiC composites

The delamination of SiC coating on C/SiC composites leads to severe oxidation of the carbon fibers and causes reliability problems of these composites during service. In this study, flexural test was conducted at room temperature to analyze the delamination behavior of SiC coating deposited on C/SiC substrate and finite element method (FEM) was adopted to simulate the interfacial crack between the SiC coating and the C/SiC substrate based on the experimental results. Results show that the fiber orientation has significant influence on the delamination of surface SiC coating. When the SiC coating is deposited parallel to the fiber orientation and interfacial delamination direction is along fiber direction, once delamination occurs, it inclines to propagate. However, when coating is prepared in other directions, the delamination inclines to be crested. The present analyses show that a proper combination of different fiber orientations can decrease the delamination of coating for better service of the materials in applications.