TOOL MADE OF CUBIC BORON NITRIDE POWDER WITH CVD COATING

Abstract

In order to increase the effectiveness of PcBN cutting tools, titanium coatings were deposited to the micropowders used in their sintering. When using the CVD method, metal transport is implemented using the iodine transport reaction, which at high temperatures ensures the formation of titanium reaction products precipitated with N and B on the surfaces of cBN grains. The results of the X-ray phase analysis of the diffractograms of the powders indicate that in addition to cubic boron nitride these samples contain the products of its reaction with titanium (TiN and TiB2 phases), as well as the intermetallic TiAl. The sintering of composites from coated powders at a pressure of 7.7 GPa and a temperature of 2300 °C in a toroid-type high-pressure apparatus does not lead to significant changes in the phase composition, but the crystal lattice parameter of TiN nitride increases from 0.4244 nm to 0.4253 nm. Comparative studies of the new composite effectiveness demonstrated a reduction its wear intensity during high-speed cutting of hardened steel in comparison with a standard PcBN composite.