New metal matrixes for cobalt-free diamond tools

摘要

A study of titanium alloys, as matrixes for diamond tools, is presented with the aim of finding new binders without cobalt. In fact even if cobalt is classified as toxic, it is a common binder for diamond tools. Moreover the exposure to a mixture of cobalt and WC powders presents an excess risk of cancer. Titanium was selected as base element of the innovative matrix because of its atoxicity and low elastic modulus. Furthermore it presents high wettability respect to diamond. Copper was added to the alloys in order to lower the sintering temperature and to increase the mechanical performances. A pressure-less sintering technique was employed and optimized for the preparation of the diamond composites. The diamond retention capability and the metal-diamond interface were evaluated by SEM on the fracture surfaces of composites. The structure of the metal matrixes was studied by XRD. Crack free composites, presenting high relative density, were obtained. They show a strong diamond-metal interface. No graphitization evidence on diamond particles was observed. The mechanical performances (hardness, flexural strength) of some metal matrixes are compatible with the commercial ones. The abrasion resistance of some metal matrixes respect to quartzite slurry is higher than that of pure cobalt.