Abstract

Up to 1955, the only form of diamond was natural diamond. However, since then it has been possible to grow diamond using High Pressure and High Temperature (HPHT techniques) as well as low pressure Chemical Vapour Deposition (CVD) methods. It is also possible to produce Polycrystalline Diamond composites (PCDs). All of these products have exceptional properties and there are a large number of potential applications. It is important to know the fracture, cleavage, strength, erosion, friction and polishing properties of all these various materials. Basic strength properties are often difficult to obtain. For example, natural diamonds are invariably small, irregular, may have internal strains and information on the impurities they contain usually requires separate investigation. To these disadvantages, can be added the one of cost; strength testing invariably involves breaking the sample! This talk reviews the current state of knowledge of the mechanical properties of all the various types of diamond and the techniques to measure them.