Young's modulus measurements of SiC coatings on spherical particles by using nanoindentation

Spherical silicon carbide coatings are deposited by fluidised bed chemical vapour deposition for the application to Tristructural Isotropic (TRISO) coated fuel particles. The silicon carbide exhibits columnar structure and grows along the radial direction during deposition. In this work, two measurements are made with nanoindentation, one is measured vertically to the grain growth direction, which gives a Young's modulus of 391.1 ± 12.9 GPa, and the other is measured along the grain growth direction which gives a Young's modulus of 442.5 ± 13.3 GPa. Finite element analysis and a theoretical effort are introduced to estimate the bending contribution when the indentation is carried out on the external surface of SiC. The relationship between grain orientation of SiC and its Young's modulus has been examined.