from the conferences organized by TANGER Ltd.
Diamond coatings provide outstanding hardness and wear resistance for cutting tools, however, their application on cemented tungsten carbide (WC–Co) is often limited by insufficient adhesion. This study addresses this challenge by introducing a thin nanocrystalline-diamond (NCD) buffer layer to enhance the adhesion of subsequently deposited microcrystalline-diamond (MCD) coatings. Two types of interlayers routinely employed in industrial applications, TiAlSiN and a SiC-based interlayer, were deposited on commercially available WC-Co inserts using magnetron sputtering.The NCD buffer, with a thickness of 750 nm, was prepared in a linear-antenna microwave plasma chemical vapour deposition (MWCVD) system at substrate temperature as low as 550 °C. After that, the MCD coatings with a thickness of 11.5 µm were deposited in focused MWCVD at 700 °C on both interlayers (TiAlSiN and SiC-based), with or without an NCD buffer layer. Scanning electron microscopy and Raman spectroscopy (sp³ diamond peak near 1331-1338 cm-1) confirmed the diamond crystalline quality and film continuity across all investigated conditions. Samples with SiC-based interlayer exhibited significantly less peeling than TiAlSiN under otherwise comparable diamond deposition conditions. Overall, the incorporation of an NCD buffer layer markedly improves adhesion, and interlayer selection is critical: the SiC-based interlayer combined with NCD consistently yields more homogeneous coverage with minimal delamination compared to TiAlSiN. These results provide a robust, industrially relevant pathway towards adherent, uniform MCD coatings on carbide tools.
Keywords: Diamond coatings adhesion, WC–Co cutting tools, nanocrystalline-diamond (NCD) buffer layer, microcrystalline-diamond (MCD) coating, high-temperature interlayers© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.