Indentation-based methods to assess fracture toughness for thin coatings

There are many techniques to determine fracture toughness. Experimental simplicity and amenability to materials evaluation are features of general indentation testing. Sometimes indentation is the only practical means of obtaining fundamental information on critical lifetime-limiting damage modes in some ceramics and coatings. Fracture patterns are dependent on the indenter geometry and material properties. The analysis of interfacial toughness by indentation has been well documented. However, no such comprehensive review is available for the analysis of fracture toughness for thin coatings based on (nano) indentation. Therefore, this paper tends to fill this gap. The mechanisms of various crack patterns and existing models used to determine the fracture toughness have been discussed in this study.