# US 5,705,263 A · Coated cutting tool

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- Number: US 5,705,263 A
- Document ID: US5705263A
- Status: Granted
- Kind: A
- Application number: 08/407,657
- Filed: 1995-03-21
- Granted: 1998-01-06
- Earliest claimed: 1994-03-22
- Assignees: Sandvik AB
- Inventors: Anders Lenander; Leif kesson
- Web page: https://patentgrep.com/patent/US5705263A

## CPC

- C23C 28/044: {coatings specially adapted for cutting tools or wear applications}
- C23C 16/30: Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C 16/32: Carbides
- C23C 16/34: Nitrides {(C23C16/303 takes precedence)}
- C23C 16/36: Carbonitrides
- C23C 28/048: {with layers graded in composition or physical properties}
- C23C 30/005: {on hard metal substrates}
- Y10T 428/24975: No layer or component greater than 5 mils thick
- Y10T 428/265: 1 mil or less
- Y10T 428/31678: Of metal
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention relates to CVD-coated cemented carbide tool used for chip forming machining. More particularly, it relates to a coating with an intermediate layer acting as a diffusion barrier thus influencing the coating structure and coating adhesion of the following layer.

## Claims

### Claim 1

In an alumina coated cemented carbide body, the improvement wherein said coating consists essentially of a first layer adjacent to the substrate comprising MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) followed by a second layer of MetC.sub.x O.sub.y N.sub.z, where 0.7.ltoreq.x+y+z.ltoreq.1.3 and 0.2<y<0.8 which is further followed by a third layer of MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) where Met is selected from the group of Ti, Zr, Hf, V, Nb and Ta and where the thickness of the first layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) is 0.5-5 .mu.m and an outer layer of alumina.

### Claim 2 (depends on 1)

In the coated body of claim 1 wherein in the third layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) has a coating thickness exceeding the total thickness of the first and second layers.

### Claim 3 (depends on 1)

In the coated body of claim 1 wherein the second layer is 0.1-5 .mu.m thick.

### Claim 4 (depends on 3)

In the coated body of claim 3 wherein the second layer is 0.2-1.0 .mu.m thick.

### Claim 5 (depends on 1)

In the coated body of claim 1 wherein the thickness of the first layer or set of layers MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) adjacent to the substrate is up to 2.0 .mu.m.

### Claim 6 (depends on 5)

In the coated body of claim 5 wherein the thickness of the first layer or set of layers MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) adjacent to the substrate is 0.5-2.0 .mu.m when the substrate is essentially free from surface cobalt.

### Claim 7 (depends on 3)

In the coated body of claim 3 wherein the thickness of the wear resistant third layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) is less than 20 .mu.m.

### Claim 8 (depends on 7)

In the coated body of claim 7 wherein the thickness of the wear resistant third layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) is 5-12 .mu.m.

### Claim 9 (depends on 1)

In the coated body of claim 1 wherein the wear resistant third layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) is TiC.sub.x N.sub.1-x where 0.05.ltoreq.x.ltoreq.0.95.

### Claim 10 (depends on 9)

In the coated body of claim 9 wherein the wear resistant third layer MetC.sub.x N.sub.1-x (0.ltoreq.x.ltoreq.1) is TiC.sub.x N.sub.1-x where 0.3.ltoreq.x.ltoreq.0.7.

### Claim 11 (depends on 1)

In the coated body of claim 1 wherein in the second layer y is 0.4<y<0.6.

### Claim 12 (depends on 9)

In the coated body of claim 9 wherein the wear resistant third layer has a preferred crystallographic growth orientation in the (220)-direction with a texture coefficient TC greater than 1.3, TC being defined as ##EQU2## where I(hkl)=measured intensity of the (hkl) reflection
I.sub.o (hkl)=standard intensity of the ASTM standard powder pattern diffraction data
n=number of reflections used in the calculation, (hkl)
reflections used are: (111), (200), (220).

### Claim 13 (depends on 12)

In the coated body of claim 12 wherein the wear resistant third layer has a preferred crystallographic growth orientation in the (220)-direction with a texture coefficient TC greater than 1.5.

### Claim 14 (depends on 12)

In the coated body of claim 12 wherein the wear resistant third layer has a preferred crystallographic growth orientation in the (220)-direction with a texture coefficient TC greater than 1.8.

### Claim 15 (depends on 1)

In the coated body of claim 1 wherein the alumina layer consists of a single phase .alpha.-alumina having a grain size s:
0.5 .mu.m<s<3 .mu.m.

### Claim 16 (depends on 1)

In the coated body of claim 1 wherein said body comprises a TiN outermost layer.

### Claim 17 (depends on 16)

In the coated body of claim 16 wherein the outermost TiN-layer is 0.01-1 .mu.m thick.