Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 13, 2020 - September 16, 2020
The environmental barrier coating (EBC) is applied to SiC-matrix composite materials, which are promising candidates for next-generation turbine blades of airplanes, so as to prevent wall-thinning by reaction with high-temperature water-vapor. As EBC comprises a multi-layer structure consisting of several layers of dissimilar materials with different material properties, EBC is expected to exhibit complex, severe thermal stress conditions. This study calculates energy release rate (ERR) for interface crack initiation and propagation by the finite element method (FEM) calculations with the aim to estimate conditions to prevent fracture by interface cracks under thermal stress due to cooling after fabrication at 1673 K. Our calculations suggested that the SiAlON layer be relatively thin while the mullite layer be thick to suppress crack initiation. It was also predicted that, with the thicknesses of the SiAlON and mullite layers of 5 and 20 μm, respectively, no crack propagation is expected as long as no initial cracks longer than 1200 μm exist.
