An analysis of spalling in the microscratch test

An analysis of the microscratch test is presented for the case when extensi ve spalling occurs ahead of the scratch. In contrast to earlier models, att ention is not focused on modeling the loads exerted on the film during a sc ratch test. Rather, the analysis relies on using the geometry of the spall to deduce the critical in-plane load for delamination and, hence, the inter facial toughness. It is shown that the extent of the spall is inversely pro portional to the fourth root of the toughness. The model is used to compute the interfacial toughness between a Pt film and a NiO substrate using expe rimental data given in the literature. The predicted toughness is very cons istent with the expected value. (C) 1998 Elsevier Science Ltd. All rights r eserved.