Abstract

Diamond is an established engineering material and displays a range of exceptional mechanical properties, depending on the particular class of sample [1, 2]. If a complete understanding of the relationships between extended and point defect structures in diamond and the subsequent macroscopic mechanical properties can be developed, then it will enable material properties such as hardness, fracture strength and fracture toughness to be engineered, to optimise the material for particular applications. One of the first steps in the process is to determine relationships between microscopic structural parameters and macroscopic material properties.

Many standard mechanical characterisation tests are challenging to carry out on diamond. For example, indentation tests require diamond indenters, themselves of unknown hardness, and even then are likely to be damaged after a relatively small number of measurements. Hence, developing alternative measurement methods is of considerable interest. Here, we describe an approach for determining the hardness, H, and fracture toughness, KIC , of diamond from solid particle erosion, by measurement of the erosion rate. Specifically, for materials that undergo brittle fracture, the erosion rate, ε, has been shown to be proportional to E / H1/3K2IC [3,4]. The method is used to study samples of CVD and HPHT diamond samples and to examine the correlation between known defect classes and concentrations and material characteristics.

[1] J. E. Field. Rep. Prog. Phys., 75(12):126505 [2] C. Yan. Phys. Status Solidi, 201(4):R25-R27 [3] F. Ericson. Mater. Sci. Eng. A, 105-106:131-141 [4] F. Ericson. Wear, 115:107-120