The microstructure and cutting performance of diamond-coated cemented carbide

In this study, diamond coatings have been deposited on WC-Co and WC-TiC-Co cemented carbides by hot filament assisted chemical vapour deposition (HFCVD). Diamond coatings deposited at different conditions were characterised by x-ray diffraction, Raman spectroscopy, scanning electron microscopy. The adhesion strength of diamond coatings were quantitatively measured by a scratch test. The cutting performance of the diamond-coated cemented carbide inserts and commercial uncoated cemented carbide inserts with the same grade and type were compared by turning tests. The coated inserts demonstrate a very small steady wear without coating flaking when turning Al-25%Si, Al-22%Si and Cu-10%Sn alloys compared with the large amount of flank wear exhibited by uncoated inserts. The tool life of the coated inserts are over 5 times longer than that of the uncoated substrate inserts. A diamond-coated cemented carbide insert is expected to be superior for cutting tools with AI-Si and Cu-Sn alloys.