Processing of composite diamond coating-based drawing die

In this paper, the drawing die of cemented carbide wolfram carbide–cobalt (WC–Co) was taken as the substrate. It was preprocessed by metallographic sandpaper, acetone, deionized water, Murakami solution and aqua regia. Direct current magnetron sputtering was adopted to sputter a tantalum (Ta) interlayer in the bore of the drawing die. By using electron-assisted chemical vapor deposition, a micro/nanocomposite coating was deposited. The specimens were characterized by applying methods such as three-dimensional profilometry, Rockwell hardness tester, scanning electron microscopy and Raman spectroscopy. The results indicated that the drawing die showed a very smooth coating surface and a compact, uniform structure; the grain size was <50 nm and the surface roughness was <10 nm. It can be inferred from the indentation tests that there was smaller internal stress in the coating and satisfactory adhesion force between the coating and the substrate. So the drawing die can satisfy the working requirement of drawing wires.