| 摘要 |
<p>A cutting tool insert for turning steel comprises a cemented carbide body and a coating. The body consists of WC, 5-11 wt.% Co and 2-10 wt.% cubic carbides of Ti, Ta and/or Nb and a highly W-alloyed binder phase with a CW-ratio of 0.76-0.92. The coating comprises: (a) a first (innermost) layer of TiCxNyOz with a thickness of 0.1-2 ~mm and with equiaxed grains having a size of less than 0.5 ~mm; (b) a layer of TiCxNyOz with a thickness of 3-15 ~mm with columnar grains having a dia. of less than 5 ~mm; and (c) an outer layer of a smooth, fine-grained (0.5-2 ~mm) kappa-Al2O3 layer having a thickness of 1-9 ~mm. The layer of TiCxNyOz with a thickness of 3-15 ~mm with columnar grains is pref. deposited by a MT-CVD technique, using acetonitrile as the C and N source for forming the layer in a preferred temp. range of 850-900 deg C. The cemented carbide pref. has 6.5-8.0 wt.% Co and a CW ratio of 0.8-0.9. The cemented carbide body has a surface zone 15-35 ~mm thick depleted from cubic carbides. The outermost layer is pref. a thin 0.1-1 ~mm TiN layer, where the outermost TiN layer has been removed along the cutting edge.</p> |
