Finite element analysis study on effect of indenter tip radius to nanoindentation behavior and coatings properties

บทคัดย่อ

This paper mainly focuses on the study of factors that affect the nanoindentation process and the determination of mechanical properties of coating film using computational finite element (FE) analysis. Attempts have been made in order to show the effect of indenter tip radius on the nanoindentation process of both hard and soft coating systems. It has been proved that larger load is required to reach a specific penetration depth when the indenter tip radius increases. Besides, the change in tip radius led to a more severe effect on hard coating system compared to soft coating system. Furthermore, pile- up and sink-in phenomena of the materials have also been proved. They affect the measurement of mechanical properties of coatings/films. The developed nanoindentation FE models were able to simulate the indentation loading-unloading curves of the coating/substrate system. It also can be found that an extraction of intrinsic properties of the thin super-hard coating film, titanium diboride or TiB2, was achieved. If the load-displacement curves of the simulation and experimental results can match with each other well, then the properties used in the simulation should be the actual properties of the coatings. The critical ratio of coating thickness to indentation depth for the property measurement was also presented. Hence, in order to get accurate measurements of properties of the film, it is necessary to know the limitation in which the penetration depth can be indented for the coating/substrate systems.