Defining the true hardness of materials harder than single crystal diamond

Abstract With the development of new synthesis methods and chemistries, a number of new superhard materials have been reported to be harder than diamond. While such materials are highly desirable due to their wide-ranging applications, there are some inherent uncertainties in the methods utilized to determine and define the hardness of such materials. In this paper, we employed the Vickers Hardness Tester to measure the hardness of nine ceramic and superhard materials within a well-defined criteria and methodology, for the reliable assessment of the hardness of these new superhard materials. These findings and the developed testing method have broad implications in the characterizing of new and emerging superhard materials, leading to new discoveries.