Nova Patents
EP0753603A2

Coated cutting insert

Abstract

The present invention discloses a coated cutting insert particularly useful for intermittent cutting in low alloyed steel. The insert is characterised by a WC-Co-based cemented carbide body having a highly W-alloyed Co-binder phase and a coating including an innermost layer of TiCxNyOz with columnar grains and a top coating of a fine grained, textured α-Al2O3-layer.

EP0753603A2, drawing sheet 1
Sheet 1 of 4

Term

Term ended

Projected expiry passed 4 July 2016, 10.2 years ago.

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6 claims: 4 independent, 2 dependent

  1. 1
    A cutting tool insert for machining of low alloyed steel comprising a cemented carbide body and a coating characterised in that said cemented carbide body consists of WC, 5 - 11 wt-% Co and 0 - 10 wt-% cubic carbides of metals from groups IVb, Vb or VIb of the periodic table and a highly W-alloyed binder phase with a CW-ratio of 0.76 - 0.93 and in that said coating comprises - a first (innermost) layer of TiC x N y O z with a thickness of 0.1 - 2 µm, and with equiaxed grains with size 0.5 µm - a layer of TiC x N y O z with a thickness of 2-15 µm with columnar grains with a diameter of about 5 µm - a layer of TiC x N y O z with a thickness of 0.1 - 2 µm and with equiaxed or needle like grains with size ≤0.5 µm - an outer layer of a smooth, textured, fine-grained (0.5 - 2 um) α-Al 2 O 3 -layer with a thickness of 2 - 10 µm
  2. 2
    Cutting insert according to the preceding claim characterised in that the α-Al 2 O 3 -layer has a texture in (012)-direction and with a texture coefficient TC(012) larger than 1.3.
  3. 5
    Cutting insert according to the preceding claims characterised in an outermost coating of a thin 0.1 - 1 µm TiN-layer.
  4. 6
    Method of making a cutting insert comprising a cemented carbide body and a coating characterised in that WC-Co-based cemented carbide body is coated with - a first (innermost) layer of TiC x N y O z with a thickness of 0.1 - 2 µm, with equiaxed grains with size 0.5 µm using known CVD-methods - a layer of TiC x N y O z with a thickness of 2 - 15 µm with columnar grains and with a diameter of about 5 µm deposited by MTCVD-technique, using acetonitrile as the carbon and nitrogen source for forming the layer in a preferred temperature range of 850 - 900 °C. - a layer of TiC x N y O z with a thickness of 0.1-2 µm with equiaxed or needle like grains with size ≤0.5 µm, using known CVD-methods - an outer layer of a smooth textured α-Al 2 O 3 -layer textured in the direction (012), (104) or (110) with a thickness of 2 - 10 µm.
Independent claims4