Hardness evaluation from a bilayer coating system of Ni-P deposited on carbon steel plates by multicycle indentation tests

Abstract The assessment of mechanical properties of materials by instrumented indentation tests have been widely performed in last years. The objective of this work was to develop a methodology to analyze the mechanical behavior of materials from the data obtained by a continuous multicycle indentation test at the microscale of loads to limit the problems associated with the heterogeneity of the materials and to increase the amount of data for the study of thick coatings that only nanoscale analysis does not provide in the case of heterogeneous coatings. To validate our approach, the hardness behavior of a two-layers coating material (Ni-P) is studied. To corroborate the values obtained by the proposed methodology, continuous stiffness measurement tests at the nanoscale were also performed. The bilayer system was found to bear satisfactorily the loading/unloading cycles and provide an important composite hardness at the surface of the coating.