Nanoindentation hardness of hot-pressed boron suboxide

The existence of the indentation size effect implies the absence of a single hardness value for the material under investigation especially at low applied loads. In this paper we present an investigation of the indentation size dependence behaviour of nanoindentation hardness in boron suboxide ceramic compacts prepared by uniaxial hot-pressing. Berkovich nanohardness indentations were conducted and analyzed accordingly. In addition to the ordinary Oliver and Pharr method of nanoindentation data analysis, a quantitative approach for the loading curve analysis is proposed. Using the proposed approach, the description and characterization of the observed indentation size effect through the application of the Meyer’s law, and the classical and the modified proportional specimen resistance models as well as the multi-fractal scaling law was conducted and is reported. The load-independent hardness values deduced from our quantitative approach are comparable to the results calculated with conventional methods, especially with the multi-fractal scaling law.

► The load-displacement indentation response of hot-pressed B6O is measured and analysed. ► The nanoindentation hardness of hot-pressed boron suboxide is reported. ► An approach is developed to simulate multi-cycling loading load-displacement curves. ► A comprehensive model inter-comparison study of the ISE in hot-pressed B6O is also presented. ► The fractal dimension is a better measure of ISE than the Meyer’s index.