Nova Patents
EP0736615A2

Coated cutting insert

Abstract

The present invention discloses a coated cutting insert particularly useful for dry milling of grey cast iron. The insert is characterized by a WC-Co cemented carbide substrate and a coating including an innermost layer of TiCxNyOz with columnar grains and a top coating of a fine-grained α-Al2O3 layer.

EP0736615A2, drawing sheet 1
Sheet 1 of 3

Term

Term ended

Projected expiry passed 19 March 2016, 10.5 years ago.

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6 claims: 4 independent, 2 dependent

  1. 1
    Cutting insert for milling of grey cast iron comprising a substrate and a coating characterised in that said substrate consists of WC, 3-15 weight-% Co and ≤2 weight-% carbides of metals from groups IVb, Vb or VIb of the periodic table and in that said coating comprises - a first (innermost) layer of TiCxNyOz with a thickness of 0.1-2 µm, and with equiaxed grains with size <0.5 µm- a layer of TiCxNyOz with a thickness of 2-10 µm with columnar grains with a diameter of about <5 µm- a layer of TiCxNyOz with a thickness of 0.1-2 µm and with equiaxed or needlelike grains with size ≤0.5 µm- an outer layer of a smooth, textured, fine-grained α-Al2O3 layer with a thickness of 2-10 µm
  2. 2
    Cutting insert according to the preceding claim characterised in that the α-Al2O3 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 substrate and a coating characterised in that WC-Co-based substrate is coated with - a first (innermost) layer of TiCxNyOz with a thickness of 0.1-2 µm, with equiaxed grains with size <0.5 µm using known CVD-methods- a layer of TiCxNyOz with a thickness of 2-10 µm with columnar grains and with a diameter of about <5 µm deposited either by MTCVD-technique, using acetonitrile as the carbon and nitrogen source for forming the layer in the temperature range of 700-900 °C, or by high temperature CVD-technique- a layer of TiCxNyOz with a thickness of 0.1-2 µm with equiaxed or needlelike grains with size ≤0.5 µm, using known CVD-methods- an outer layer of a smooth textured α-Al2O3 layer with a thickness of 2-10 µm according to known CVD-technique.
Independent claims4