The structure and properties of a hard alloy coating deposited by high-velocity pulsed plasma jet onto a copper substrate

Using a plasmatron operating in specially calculated regimes, tungsten carb ide (WC) based coatings were deposited onto a copper crystallizer plate. It was found that a local hardness of the WC-Co coating may reach up to 1.3 x 10(4) N/mm(2) and the coating adhesion to substrate may be as high as 270 MPa. The elemental and phase compositions of coatings were studied by Ruthe rford backscattering spectroscopy, X-ray diffraction, and transmission elec tron microscopy with electron diffraction. The surface morphology and depth -composition profiles of the coatings were studied by optical and scanning electron microscopy. The coating is composed of WC crystal grains with hexa gonal close packed (hcp) lattice, alpha- and beta -Co grains, and cubic WC grains. The average size of the hcp WC grains is 0.15 mum and that of the c obalt particles is about 25 nm. In addition, the grain boundaries contain W 3Co3C particles with an average size of 15 nm. (C) 2001 MAIK "Nauka/Interpe riodica".