Experimental and FEM based investigation of the influence of the deposition temperature on the mechanical properties of SiC coatings

Scanning electron microscopy shows that the microstructure, in particular the overall grain size, of chemical vapor deposited silicon carbide coatings depends on the deposition temperature. So far, the influence of the microstructure on the mechanical properties of such coatings is not well described in literature. To investigate the influence of the deposition temperature on the mechanical properties of the coating, nanoindentation is used in this work. Since the measurement results of nanoindentation can be affected by the substrate material, the contribution of the substrate material is taken into account utilizing a finite element model. The model is then employed to generate information about elastic and plastic properties of the coating by inverse simulation. To evaluate the fracture toughness of the coating, the generated material model is used in a cohesive-zone based formulation of the fracture process during indentation at higher loads. The results of this model allow determining the fracture toughness of silicon carbide coatings deposited at different temperatures.