Micromechanical characterization of electrophoretic-deposited green films

Low-load indentation experiments have been performed on electrophoretic-deposited films of SiC particles on a graphite substrate. Films with thicknesses between 60 and 300 mu m prepared at two current intensities and subsequently dried under different humidities were indented with spherical indenters with nominal radii of 10, 50, and 150 mu m Force-displacement data were analyzed to,determine contact pressure and elastic modulus versus depth results. The modulus and contact pressure behavior with depth exhibited opposite trends with indenter radius: the modulus increase was least for the 10 pm and greatest for the 150 mu m, whereas the contact pressure was the inverse. The results may be rationalized by plotting modulus normalized to the ratio "contact radius/film thickness" (a/t), whereas the contact pressure results at small a/t could be normalized when plotted versus contact strain, i.e,, contact radius divided by indenter radius (a/R). These approaches enabled the properties of the variously deposited films to be compared. Additional interesting microstructural and cracking behavior patterns are also reported.