A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 2 3 8 iTSSe TSS iTSSe TSS In a nanoindentation test, the size of the residual impression is often only a few micrometers, so direct imaging becomes difficult. Here, the depth of penetration beneath the specimen surface is measured as the load is applied to the indenter. From the known geometry of the indenter, the size of the area of contact is determined. NANOINDENTATION Nanoindentation is mainly used to determine the hardness and elasticmodulus of the coating. Conventional indentation techniques, including standard microhardness tests, involve measurement of the size of a residual plastic impression in the specimen as a function of the indenter load. From the area of contact, the hardness of the material is inferred. Fig. 2 — Microhardness as a function of (a) coating thickness, (b) temperature, and (c) time for an IN625 coating on an AISI steel substrate. (a) (b) (c) FEATURE 8
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