Evaluation of surface hardness of NiCr coating using Finite Elements Analysis

Abstract

Introduction: To enhance resistance to surface damage of materials due to mechanical actions, there have been created many procedures that allow its modification for different needs. This leads to researches conducted to determine the changes achieved in the properties due to said procedures. One method commonly applied is, for example, physical means of vapor deposition of thin films on a surface. In recent years, many rational and empirical models have been proposed for the study of said properties. One of these models is computational analysis, which allows determining a great number of properties while avoiding applying destructive tests, achieving to reduce experimental time spent and costs of manufacture of test tubes as well as the test itself. In this research, the hardness of a surface coating of Nichrome (NiCr 80-20) was determined with an indentation test modeled in Ansys, based on the finite elements' method. Objective:  To design a computational model that allows determining the surface hardness of material with coating Method: The realization of this project was made with the software for engineering analysis ANSYS, and the model was made based on the Vickers Indentation Test regulation given by the ASTM, which states that the test must be done with a pyramidal diamond indenter, applying forces greater than 1 kgf. Results: By running the respective numerical analysis for both the substrate and the coating, a surface hardness of 197.5073 VH was obtained for NiCr coating and surface hardness of 160.5809 VH for the S235 Steel (hardness of the interface).   Conclusions: It was determined that the model proposed is correct seeing as the values obtained for the Vickers' Hardness is approximately the same as the experimental value with an error of 0.7501% for the coating layer and 0.2605% for the substrate. It was also concluded that it is possible to use this same procedure to obtain the surface hardness for different materials than those treated in this article by using this tool. In this research the hardness of a surface coating of Nichrome (NiCr 80-20) was determined with an indentation test modeled in Ansys, based on the finite elements’ method [1]. Objective:  To design a computational model that allows to determine the surface hardness of a material with coating Method: The realization of this project was made with the software for engineering analysis ANSYS, and the model was made based on the Vickers Indentation Test regulation given by the ASTM [2], which states that the test must be done with a pyramidal diamond indenter, applying forces greater than 1 kgf. Results: By running the respective numerical analysis for both the substratum and the coating, a surface hardness of 197.5073 VH was obtained for the S235 Steel (hardness of the interface) and a surface hardness of 160.5809 VH for the NiCr coating. Conclusions: It was determined that the model proposed is correct seeing as the values obtained for the Vickers’ Hardness is approximately the same as the experimental value with an error or 0.7501% for the substratum and 0.2605% for the coating layer. It was also concluded that it is possible to use this same procedure to obtain the surface hardness for different materials than those treated in this article by using this tool.