Nanoindentation of Hard Coatings

Consten, N. (2014) Nanoindentation of Hard Coatings.

Abstract:Nanoindentation measurements were carried out using the coatings CrAlTiN, CrAlSiN (with high Cr/Al ratio), AlCrSiN (with low Cr/Al ratio) and CrAlN deposited by cathodic arc technology on tungsten carbide substrates. For this purposes use is made NanoTest Vantage Platform 4 of Micro Materials with a diamond Berkovich indenter. The maximum depth of penetration in a test is restricted to no more than 10% of the film thickness to avoid unintentional probing of the properties of the substrate. Hardness and reduced Young’s modulus values are extracted from measured load-displacement curves. For statistical purposes, mean values of hardness and reduced Young’s modulus are quoted from a set of indentation curves acquired under the same parameters. The data were strongly scattered due to the surface roughness and morphology as the surface exhibits a lot of droplets and holes typical for low-arc cathodic deposition. The indentation procedure is simulated as a Static Structural Analysis using the Mechanical APDL of ANSYS Workbench 14.0. The indentation procedure is modeled as a 2D axial-symmetric problem. A conical indenter with a semi-angle of is used as this gives the same area to depth ratio as a triangular Berkovich indenter. Young’s modulus from the nanoindentation measurements serves as input for the model. Linear work hardening is assumed and these plastic material parameters are determined by comparing load-displacement curves from nanoindentation measurements and the finite element simulation. Tip rounding of the indenter is found to have a big influence on the load-displacement curves and plastic material properties. The radius value of this rounding is not known. Due to this one cannot draw firm conclusions about the found values.
Item Type:Internship Report (Master)
University of Southampton, United Kingdom
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Keywords:Nanoindentation, young's modulus, hardness, finite element method, ansys, elasticity, plasticity
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