High hardness/high compressive stress multilayer coated tool
AssigneesKennametal Inc., Balzers Aktiengesellschaft
InventorsDennis T. Quinto, Helmut J. Kaufmann
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Abstract
A cutting tool is provided composed of a hard substrate having a PVD coating thereon having three layers. The innermost or first layer is composed of a group IVB (titanium, hafnium or zirconium) metal nitride. The middle or second layer is composed of a group IVB carbonitride. The outermost or third layer is also composed of a group IVB metal nitride. The PVD coating is characterized by high hardness and high residual compressive stresses.
Claims18
A cutting tool comprising:
- a body having a first face and a second face;
- a cutting edge located at the junction of said first face and said second face;
- said body composed of a substrate and a coating adherently bonded to said substrate;
- said substrate composed of a hard material selected from the group consisting of tool steels, cemented carbides and cermets;
- said coating having a first layer composed of a group IVB metal nitride deposited by physical vapor deposition and adherently bonded to said substrate;
- said coating have a second layer composed of a group IVB metal carbonitride deposited by physical vapor deposition and adherently bonded to the outside of said first layer;
- said coating having a third layer composed of a group IVB metal nitride deposited by physical vapor deposition and adherently bonded to the outside of said second layer;
- wherein said coating contains an average compressive residual stress exceeding about 350 Kg/mm.sup.2 ;
- wherein said coating has an average Vickers Hardness Number (50 gm/load) between about 2600 to 3100 kg/mm.sup.2 ;
- and wherein said first layer has a thickness exceeding 1 micrometer but which is less than 3 micrometers.
The cutting tool according to claim 8 wherein said second layer is composed of titanium carbonitride and said first layer is composed of titanium nitride.
A cutting tool comprising:
- a body having a first face and a second face;
- a cutting edge located at the junction of said first face and said second face;
- said body composed of a substrate and a coating adherently bonded to said substrate;
- said substrate composed of a hard material selected from the group consisting of tool steels, cemented carbides and cermets;
- said coating having a first layer composed of a group IVB metal nitride deposited by physical vapor deposition and adherently bonded to said substrate;
- said coating having a second layer composed of a group IVB metal carbonitride deposited by physical vapor deposition and adherently bonded to the outside of said first layer;
- said coating having a third layer composed of a group IVB metal nitride deposited by physical vapor deposition and adherently bonded to the outside of said second layer;
- wherein said coating has an average Vickers Hardness Number (50 gm/load) between about 2600 and 3100 Kg/mm.sup.2 ;
- wherein said coating contains an average compression residual stress exceeding about 350 Kg/mm.sup.2 ;
- wherein the compositions of the metal carbonitride in the second layer varies with distance from the substrate, such that as the second layer extends away from the substrate there is a first maximum and then a second maximum in the carbon content of the metal carbonitride and wherein between said first and second maximum, the carbon content of said metal carbonitride reaches a value which is less than the first maximum in carbon content.
Dependencies are inferred from the claim text.