In situ synthesis of cBN–Ti3AlC2 composites by high‐pressure and high‐temperature technology

Abstract

In this paper, titanium aluminum carbide (Ti3AlC2) was studied as the binder of polycrystalline cubic boron nitride (PCBN) to overcome the weaknesses of traditional metal binders and ceramic binders. The composites of cubic boron nitride (cBN) and Ti3AlC2 were in situ synthesized from the mixtures of Ti, Al, TiC and cBN powders at high temperature (1050°C–1250°C) and under high pressure (4.5GPa) (HTHP). The Ti3AlC2 proportion in as-prepared composites increased as the processing temperature increased from 1050°C to 1150°C. At 1200°C, part of Ti3AlC2 decomposed to form new TiC. At 1250°C, cBN transformed to hBN and reacted with other materials. The composites processed at 1200°C had the optimal mechanical properties, including friction coefficient, hardness and mass loss of worn Si3N4 ball. From the microstructure of as-prepared composites, agglomeration of cBN particles existed; however, the cBN particles, in general, were evenly distributed in the matrix of Ti3AlC2. The cBN particles strongly bonded with the matrix with a clear interface.