Coated body and method for production of the body

Abstract

A coated body having a substrate and a wear-resistant coating applied to the substrate by physical vapor deposition, the coating comprising a main layer applied to the substrate in a thickness of 1 to 10 μm, wherein said main layer is formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and a cover layer adjacent to the main layer at a thickness of 0.1 to 5 μm, wherein the cover layer comprises at least one alternating layer consisting of an oxynitride layer and a nitride layer arranged over the oxynitride layer, wherein the oxynitride layer is formed from an oxynitride of aluminum and optionally further metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof, and the nitride layer is formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof.

Claims

1. Coated body having a substrate and a wear-resistant coating applied to the substrate by physical vapor deposition, the coating comprising: a main layer applied to the substrate in a thickness of 1 to 10 μm, wherein said main layer is formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and a cover layer adjacent to the main layer in a thickness of 0.1 to 5 μm, wherein the cover layer comprises at least one alternating layer consisting of an oxynitride layer, an intermediate layer formed from an oxynitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof, and a nitride layer arranged over the oxynitride layer and the intermediate layer, wherein the oxynitride layer is formed from an oxynitride of aluminum and optionally further metals from the group consisting of chromium, hafnium, zirconium, yttrium, silicon and combinations thereof, and the nitride layer is formed from a nitride of aluminum and at least one other metal from the group consisting of Ti, Cr, Si, Zr and combinations thereof; and wherein the oxynitride layer has a nitrogen component of less than 50 atomic percent with respect to the proportion of nitrogen and oxygen in the oxynitride layer.

2. The coated body according to claim 1, characterized in that the main layer of the coating consists of aluminum titanium nitride.

3. The coated body according to claim 1, wherein the main layer has an Al:Ti atomic ratio in a range from 60:40 to 70:30.

4. The coated body according to claim 3, characterized in that the main layer has an Al:Ti ratio in a range of 62:38 to 65:35.

5. The coated body according to claim 1, characterized in that the cover layer adjoining the main layer in the coating has 1 to 10 iterations of the at least one alternating layer.

6. The coated body according to claim 1, characterized in that the thickness of an alternating layer consisting of the oxynitride layer, the intermediate layer and the nitride layer is in a range from 0.1 μm to 1 μm.

7. The coated body according to claim 1, characterized in that the oxynitride layer in the at least one alternating layer is formed from an oxynitride of aluminum or oxynitride of aluminum and chromium.

8. The coated body according to claim 7, characterized in that the at least one alternating layer is formed from AlO.sub.xN.sub.1-x with 0.5<x≤0.99.

9. The coated body according to claim 7, characterized in that the at least one alternating layer is formed from (Al,Cr)O.sub.xN.sub.1-x with 0.5<x≤0.99.

10. The coated body according to claim 1, characterized in that the oxynitride layer in each case consists of 1 to 30 atomic % nitrogen.

11. The coated body according to claim 10, characterized in that the oxynitride layer consists of 2 to 15 atomic % nitrogen.

12. The coated body according to claim 1, characterized in that the intermediate layer consists of an oxynitride of aluminum and titanium.

13. The coated body according to claim 1, characterized in that the intermediate layer is further arranged between the main layer and the at least one intermediate layer adjacent thereto.

14. The coated body according to claim 1, characterized in that the coating comprises an outermost layer of TiN, ZrN, CrN and/or AlCrN overlying the cover layer.

15. The coated body according to claim 1, characterized in that the intermediate layer consists of (Al,Ti)O.sub.xN.sub.1-x with 0<x<1.

Description

(1) Further features and advantages of the present invention will become apparent from the following description of a preferred embodiment. However, the following examples only serve to illustrate the invention and are not to be construed in a restrictive sense.

PRODUCTION EXAMPLE 1

(2) In a PVD coating system of the Innova™ type from the company Oerlikon Balzers, a substrate for a cutting tool made of tungsten carbide hard metal with about 10% by weight Co was provided by arc vapor deposition with a main layer consisting of AlTiN and a cover layer consisting of three successive alternating layers, each having an oxynitride layer consisting of AlO.sub.xN.sub.1-x and a nitride layer consisting of AlTiN.

(3) An intermediate layer of AlTiO.sub.xN.sub.1-x having an oxygen gradient was deposited between the main layer and the oxynitride layer of the first alternating layer, between the oxynitride layer and the nitride layer of each alternating layer, and between the adjacent alternating layers in each case.

(4) A cathode having a composition of Al67Ti33 (atomic %) was used to deposit the titanium-containing layers. For the total duration of coating the nitrogen partial pressure was controlled in a range from 3.0 to 3.5 Pa. Oxygen was supplied at a volume flow of 30 to 50 sccm during deposition of the oxynitride layers and the intermediate layers.

(5) The AlTiN main layer had a thickness of 3.7 μm. The total thickness of the cover layer was 1.9 μm which resulted in a total thickness of the coating of 5.6 μm.

(6) Further parameters of the coating deposited on the substrate are given in Table 1 below:

(7) TABLE-US-00001 TABLE 1 PVD coating system Layer Composition Cathodes Main layer AlTiN AlTi Cover layer Intermediate layer AlTiO.sub.xN.sub.i−x AlTi/Al Oxynitride layer AlO.sub.xN.sub.i−x Al Intermediate layer AlTiO.sub.xN.sub.i−x AlTi/Al Nitride layer AlTiN AlTi Intermediate layer AlTiO.sub.xN.sub.i_x AlTi/Al Oxynitride layer AlO.sub.xN.sub.i−x Al Intermediate layer AlTiO.sub.xN.sub.i−x AlTi/Al Nitride layer AlTiN AlTi Intermediate layer AlTiO.sub.xN.sub.i−x AlTi/Al Oxynitride layer AlO.sub.xN.sub.i−x Al Intermediate layer AlTiO.sub.xN.sub.i−x AlTi/Al Nitride layer AlTiN AlTi

PRODUCTION EXAMPLE 2

(8) A substrate for a tungsten carbide hard-metal cutting tool having about 10% by weight Co was provided in a PVD coating system by arc vapor deposition with a main layer of AlTiN and a cover layer consisting of a single alternating layer with an oxynitride layer of (Al,Cr)O.sub.xN.sub.1-x and a nitride layer of AlTiN.

(9) An intermediate layer of (Al,Cr)TiO.sub.xN.sub.1-x with an oxygen gradient was deposited in each case between the main layer and the oxynitride layer of the intermediate layer, and between the oxynitride layer and the nitride layer in the intermediate layer.

(10) The layers were in each case deposited according to the parameters specified in Production Example 1. To deposit the oxynitride layer as well as the intermediate layer, a cathode with a composition Al70Cr30 (atomic %) was used instead of the aluminum cathode. The main layer and the nitride layer were each deposited using an AlTi cathode.

(11) The AlTiN main layer had a thickness of 3.6 μm. The total thickness of the cover layer was 0.8 μm which resulted in a total thickness of the coating of 4.4 μm.

PRODUCTION EXAMPLE 3

(12) In a PVD coating system, a hard metal substrate for a cutting tool was produced consisting of 85.5% by weight tungsten carbide, 2.5% by weight mixed carbides and 12% by weight Co having a main layer of AlTiN and a cover layer of three successive intermediate layers, each having an oxynitride layer of AlO.sub.xN.sub.1-x and a nitride layer of AlTiN.

(13) An intermediate layer of AlTiO.sub.xN.sub.1-x having an oxygen gradient was deposited between the main layer and the oxynitride layer of the first alternating layer, between the oxynitride layer and the nitride layer of each alternating layer, and between the adjacent alternating layers in each case. The further coating parameters corresponded to those of Production Example 1.

(14) The AlTiN main layer had a thickness of 3.5 μm. The total thickness of the cover layer was 1.8 μm, so that a total thickness of the coating of 5.3 μm resulted.

PRODUCTION EXAMPLE 4

(15) A hard metal substrate was provided in a PVD coating system for a cutting tool consisting of 81.5% by weight tungsten carbide, 10.5% by weight cubic mixed carbides and 8% by weight Co with a main layer of AlTiN and a cover layer of three successive alternating layers, each with an oxynitride layer of (Al,Cr)O.sub.xN.sub.1-x and a nitride layer of AlTiN.

(16) Between the main layer and the oxynitride layer of the alternating layer, as well as between the oxynitride layer and the nitride layer in the alternating layer in each case, an intermediate layer was deposited of (Al,Cr)TiO.sub.xN.sub.1-x having an oxygen gradient.

(17) The layers were deposited according to the parameters specified in Production Example 1. To deposit the oxynitride layers as well as the intermediate layers, a cathode with a composition Al85Cr15 (atomic %) was used in place of the aluminum cathode.

(18) The AlTiN main layer had a thickness of 3.1 μm. The total thickness of the cover layer was 1.8 μm, so that a total thickness of the coating of 4.9 μm resulted.

COMPARATIVE EXAMPLE 1

(19) For comparison, the hard metal substrates of Production Examples 1 to 4 were provided with an AlTiN coating by arc vapor deposition in a PVD coating system of the Innova™ type from the company Oerlikon Balzers. The Al:Ti atomic ratio was about 67:33. The AlTiN coating had a thickness in the range of about 3.3 to 4.1 μm.

COMPARATIVE EXAMPLE 2

(20) In a PVD coating system, a hard metal substrate was provided for a cutting tool of 85.5% by weight tungsten carbide, 2.5% by weight mixed carbides and 12% by weight Co with a main layer of AlTiN and a cover layer of a single alternating layer with an oxynitride layer of (Al,Cr).sub.2O.sub.3 and a nitride layer of AlTiN. To deposit the oxynitride layer, a cathode was used with an atomic ratio of Al:Cr of 70:30.

(21) The AlTiN main layer had a thickness of 2.8 μm. The total thickness of the cover layer was 2.0 μm, so that a total thickness of the coating of 4.8 μm resulted.

(22) Cutting Test 1

(23) Cutting tools according to Production Example 1 with a cutting plate geometry of HNGJ0905ANSN-GD were used in milling tests using a 6-tooth face milling cutter on a workpiece made of steel of type 1.4301, and compared with corresponding cutting tools coated according to Comparative Example 1.

(24) The milling cutter was operated in a single-tooth test with a cutting speed vc of 120 m/min and a cutting depth ap of 1 mm at a contact width of 55 mm. The tooth feed was 0.25 mm. The milling was carried out dry without cooling.

(25) The end of service life was defined by a flank wear>0.2 mm, or fracture of the cutting edge.

(26) A service life of 7.5 m milling length was achieved with the coated cutting tools according to the invention. The service life of the coated cutting tools according to Comparative Example 1 was only 4.5 m.

(27) Cutting Test 2

(28) Cutting tools according to Production Example 1 with a cutting plate geometry of HNGJ0905ANSN-GD were used in milling tests using a 6-tooth face milling cutter on a workpiece made of steel of type 1.4301, and compared with corresponding cutting tools coated according to Comparative Example 2.

(29) The milling cutter was operated in a single-tooth test with a cutting speed vc of 100 m/min and a cutting depth ap of 1 mm at a contact width of 55 mm. The tooth feed was 0.25 mm. Milling was carried out with emulsion cooling.

(30) The end of service life was defined by a flank wear>0.2 mm, or fracture of the cutting edge.

(31) A service life of 2.4 m milling length was achieved with the coated cutting tools according to the invention. The service life of the cutting tools coated according to Comparative Example 1 was only 1.8 m.

(32) Cutting Test 3

(33) Cutting tools according to Production Example 3 with a cutting plate geometry of XPHT160412 were used in milling tests using a 6-tooth face milling cutter on a workpiece made of steel of type 1.4301, and compared with corresponding cutting tools coated according to Comparative Examples 1 and 2.

(34) The milling cutter was operated in a single-tooth test with a cutting speed vc of 250 m/min and a cutting depth ap of 2.5 mm at a contact width of 24 mm. The tooth feed was 0.15 mm. The milling was carried out without cooling.

(35) The end of service life was defined by a flank wear>0.3 mm, or fracture of the cutting edge.

(36) A service life of 2.1 m milling length was achieved with the coated cutting tools according to the invention. The service life of the cutting tools coated according to Comparative Examples 1 and 2 was only 1.2 m in each case.

(37) Cutting Test 4

(38) Cutting tools according to Production Example 4 with a cutting plate geometry of XPHT160412 were used in milling tests using a 6-tooth face milling cutter on a workpiece made of spheroidal graphite of type EN-GJS-700, and compared with corresponding cutting tools according to Comparative Example 1.

(39) The milling cutter was operated in a single-tooth test with a cutting speed vc of 250 m/min and a cutting depth ap of 1 mm at a contact width of 20 mm. The tooth feed was 0.25 mm. The milling was carried out without cooling.

(40) The end of service life was defined by a flank wear>0.1 mm, or fracture of the cutting edge.

(41) A service life of 12.8 m milling length was achieved with the coated cutting tools according to the invention. The service life of the cutting tools coated according to Comparative Example 1 was only 9.0 m.

(42) The coating according to the invention thus enables an extension of the service life of the cutting tools by more than 30%, sometimes considerably more than 70%.