PARAMETERS ASSOCIATED WITH ERRORS IN THE NANOINDENTATION AT LOW LOAD

摘要

In the nanoindentation at very low load, various parameters give difficulties in estimating mechanical properties. These parameters are the uncertainties of the indenter geometry and limitations including minimum detectable load and surface roughness. The geometrical deviation in the indenter tip shape and surface roughness are key parameters of errors related to measurement of mechanical properties by nanoindentation at very low load. Therefore, in this work, the effect of surface roughness on the indentation hardness was studied for fused silica wafer, fused silica plate and silicon wafer, which have different roughness values one another. To compare the theoretical values with the measured ones, the effect of the indenter tip geometry was studied using the simulation of the finite element analysis (FEA), neglecting other effects, such as indentation size effect (ISE) and surface roughness. As a result, the geometrical deviation in the indenter tip shape was observed to affect the indentation hardness and the contact area at low load. The roughness of specimens is assumed to be related to the scattering of the evaluated indentation hardness.