High-pressure sintered polycrystals from Ti-coated cBN powders: microstructure, mechanical properties and thermo-electrical characteristics

Gubernat, A ORCID: https://orcid.org/0000-0002-8815-2943, Klimczyk, P ORCID: https://orcid.org/0000-0002-8060-1388, Pasierb, P, Rutkowski, P ORCID: https://orcid.org/0000-0001-6181-5981, Kornaus, K ORCID: https://orcid.org/0000-0001-5762-7742, Lach, R ORCID: https://orcid.org/0000-0001-8513-6780, Kulczyk-Malecka, J ORCID: https://orcid.org/0000-0002-4905-3635 and Morgiel, J (2025) High-pressure sintered polycrystals from Ti-coated cBN powders: microstructure, mechanical properties and thermo-electrical characteristics. Journal of the European Ceramic Society, 45 (11). 117393. ISSN 0955-2219

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Abstract

Three grades of Ti-coated cubic boron nitride (cBN) powders, varying in grain size and coating thickness, were used to create high-pressure, high-temperature (HPHT) sintered polycrystalline materials (PcBN) without addition of bonding phases. The resulting pore-free composites exhibited a Young's modulus of 620–850 GPa and Knoop hardness between 22 and 29 GPa. The composites consist of cBN grains uniformly surrounded by titanium compounds, mainly TiN and TiB2, initially formed during the coating process and then crystalized during HPHT sintering, due to due to the high reactivity of titanium with cBN. Impedance spectroscopy and laser flash analysis indicated that microstructure of composites significantly influences their electrical and thermal conductivities, with notable temperature-dependent changes. These composites can be considered promising for advanced cutting tools, particularly in developing smart tools that can self-diagnose wear based on electrical property changes during cutting.