LAMINATED HARD COATING AND MOLDING DIE

Abstract

A laminated hard film is obtained by laminating a layer A and a layer B. The layer A has a composition different from that of the layer B. The layer A is formed of (Ti.sub.aCr.sub.bAl.sub.cSi.sub.d)(C.sub.xN.sub.1-x) and satisifies the relationship of 0≦a≦0.10, 0.10≦b≦0.50, 0.50≦c≦0.90, 0≦d≦0.05, a+b+c+d=1 and 0≦x≦0.5. The layer B is formed of (Cr.sub.eSi.sub.1-e)(C.sub.yN.sub.1-y) and satisfies the relationship of 0.90≦e≦1.0 and 0≦y≦0.5, or is formed of (Al.sub.fSi.sub.1-f)(C.sub.2N.sub.1-z) and satisfies the relationship of 0.90≦f≦1.0 and 0≦x≦0.5. Each of the layer A and the layer B has a thickness of 2 to 100 nm, and the layer A and the layer B are each alternately laminated.

Claims

1. A laminated hard film obtained by laminating a layer A and a layer B, the layer A having a composition different from that of the layer B, wherein the layer A is formed of (Ti.sub.aCr.sub.bAl.sub.cSi.sub.d)(C.sub.xN.sub.1-x) and satisfies the relationship of 0≦a≦0.10, 0.10≦b≦0.50, 0.50≦c≦0.90, 0≦d≦0.05, a+b+c+d=1 and 0≦x≦0.5, when atomic ratios of Ti, Cr, Al, Si and C are defined as a, b, c, d and x, respectively, the layer B is formed of (Cr.sub.eSi.sub.1-e) (C.sub.yN.sub.1-y) and satisfies the relationship of 0.90≦e≦1.0 and 0≦y≦0.5, when atomic ratios of Cr and C are defined as e and y, respectively, or is formed of (Al.sub.fSi.sub.1-f)(C.sub.zN.sub.1-z) and satisfies the relationship of 0.90≦f≦1.0 and 0≦y≦0.5, when atomic ratios of Al and C are defined as f and z, respectively, and each of the layer A and the layer B has a thickness of 2 to 100 nm, and the layer A and the layer B are each alternately laminated.

2. The laminated hard film according to claim 1, wherein the atomic ratio of Al to a total of Ti, Cr, Al and Si in the layer A and the layer B falls within a range of 020 to 0.60.

3. The laminated hard film according to claim 1, wherein Ti in the layer A is at least partially substituted with Zr.

4. A molding die comprising the laminated hard film according to claim 1, a substrate surface.

5. A molding die comprising the laminated hard film according to claim 3, a substrate surface.

6. The molding die according to claim 4, comprising an intermediate layer of CrN having a thickness of 3 to 10 μm between the laminated hard film and the substrate.

7. The molding die according to claim 5, comprising an intermediate layer of CrN having a thickness of 3 to 10 μm between the laminated hard film and the substrate.

8. The molding die according to claim 6, which is suitable for hot forming of a steel material.

9. The molding die according to claim 7, which is suitable for hot forming of a steel material.

10. The laminated hard film according to claim 2, wherein Ti in the layer A is at least partially substituted with Zr.

11. A molding die comprising the laminated hard film according to claim 2 on a substrate surface.

12. A molding die comprising the laminated hard film according to claim 10 on a substrate surface.

13. The molding die according to claim 11, comprising an intermediate layer of CrN having a thickness of 3 to 10 μm between the laminated hard film and the substrate.

14. The molding die according to claim 12, comprising an intermediate layer of CrN having a thickness of 3 to 10 μm between the laminated hard film and the substrate.

15. The molding die according to claim 13, which is suitable for hot forming of a steel material.

16. The molding die according to claim 14, which is suitable for hot forming of a steel material.

Description

EXAMPLES

[0055] The present invention is described more specifically below with reference to examples. However, it should be construed that the present invention is in no way limited by the following examples, and appropriate changes may be made without departing from the spirit and scope of the present invention described above and later. All of those are also included in the technical scope of the present invention.

Example 1

[0056] Monolayer or laminated films having compositions shown in the following Table 1 were formed by an ATP system. At this time, targets corresponding to respective metal parts of layers A and layers B were used as targets. In addition, a fine particle WC—Co—based cemented carbide ball with a diameter of 10 mm, which had the same composition as a fine particle cemented carbide HTi10 manufactured by Mitsubishi Materials Corporation was used, after a surface thereof was mirror-finished. As for test Nos. 1 to 31 in the following Table 1, CrN films having a thickness of 5 μm were formed as intermediate layers prior to the formation of the films. Further, as for test No. 32, the film was directly formed on a substrate surface without forming an intermediate layer.

TABLE-US-00001 TABLE 1 Number of Layer A Layer B Times Compo- Compo- of sition Thick- sition Thick- lami- Test (Atomic ness (Atomic ness nating No. Ratio) (nm) Ratio) (nm) (times) 1 TiN 5000 — — — 7 CrN 5000 — — — 3 (Ti.sub.0.5Al.sub.0.5)N 5000 — — — 4 (Al.sub.0.5Cr.sub.0.5)N 5000 — — — 5 (Al.sub.0.5Cr.sub.0.5)N 1 CrN 1 2500 6 (Al.sub.0.5Cr.sub.0.5)N 3 CrN 3 833 7 (Al.sub.0.5Cr.sub.0.5)N 10 CrN 10 250 8 (Al.sub.0.5Cr.sub.0.5)N 15 CrN 15 125 9 (Al.sub.0.5Cr.sub.0.5)N 30 CrN 30 83 10 (Al.sub.0.5Cr.sub.0.5)N 50 CrN 50 50 11 (Al.sub.0.5Cr.sub.0.5)N 100 CrN 100 25 12 (Al.sub.0.5Cr.sub.0.5)N 300 CrN 300 8 13 (Al.sub.0.3Cr.sub.0.7)N 10 CrN 10 250 14 (Al.sub.0.7Cr.sub.0.3)N 10 CrN 10 250 15 (Al.sub.0.9Cr.sub.0.1)N 10 CrN 10 250 16 (Al.sub.0.5Cr.sub.0.5)(C.sub.0.1N.sub.0.9) 10 Cr(C.sub.0.1N.sub.0.9) 10 250 17 AlN 10 CrN 10 250 18 (Al.sub.0.5Cr.sub.0.45Si.sub.0.05)N 10 CrN 10 250 19 (Al.sub.0.45Cr.sub.0.45Si.sub.0.1)N 10 CrN 10 750 20 (Ti.sub.0.05Al.sub.0.5Cr.sub.0.45)N 10 CrN 10 250 21 (Ti.sub.0.2Al.sub.0.4Cr.sub.0.4)N 10 CrN 10 250 22 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.4 10 CrN 10 250 Si.sub.0.05)N 23 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.4 10 (Cr.sub.0.95Si.sub.0.05)N 10 250 Si.sub.0.05)N 24 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.4 10 (Al.sub.0.95Si.sub.0.05)N 10 250 Si.sub.0.05)N 25 (Al.sub.0.5Cr.sub.0.5)N 10 (Cr.sub.0.95Si.sub.0.05)N 10 250 26 (Al.sub.0.5Cr.sub.0.5)N 10 (Cr.sub.0.8Si.sub.0.2)N 10 250 27 (Ti.sub.0.03Zr.sub.0.02Al.sub.0.5 10 CrN 10 250 Cr.sub.0.45)N 28 (Zr.sub.0.05Al.sub.0.5Cr.sub.0.45)N 10 CrN 10 750 29 (Al.sub.0.5Cr.sub.0.5)N 10 AIN 10 250 30 (Al.sub.0.5Cr.sub.0.5)N 10 (Al.sub.0.95Si.sub.0.05)N 10 250 31 (Al.sub.0.5Cr.sub.0.5)N 10 (Al.sub.0.85Si.sub.0.15)N 10 250 32 (Al.sub.0.5Cr.sub.0.5)N 10 CrN 10 250

[0057] Specifically, the substrate as a body to be treated was heated to a temperature of 400° C. by a heater mounted in a chamber of the above ATP system, and cleaning of the substrate surface by Ar ion was performed. The cleaning conditions were atmosphere: Ar, pressure: 0.6 Pa, voltage: 500 V and time: 5 min

[0058] Thereafter, in a nitrogen atmosphere or an atmosphere of nitrogen+methane in the case of a C-containing film, the pressure in the chamber was adjusted to 4 Pa, and an arc discharge was started at a discharge current of 150 A to form a film having a total thickness of about 5 μm (about 5,000 nm) on the substrate. During the deposition, a bias voltage of 50 V was applied to the substrate so that the substrate has a minus potential to an earth potential.

[0059] When laminated hard films were formed as shown in test Nos. 5 to 32 in the above Table 1, the targets having compositions of the layers A and the layers B were attached to separate evaporation sources, respectively, and a table on which the substrate was mounted was rotated in the AlP system. First, only the target of the layers A was independently discharged in the nitrogen atmosphere or the nitrogen-methane atmosphere for a short period of time to form the layer A on a surface of the above intermediate layer or the substrate surface. Then, the target of the layers B was discharged, and thereafter, the table was rotated while concurrently discharging the layers A and the layers B, thereby forming a multilayer film.

[0060] In the above example, after the layer A was formed on the surface of the intermediate layer or the substrate surface, the layer B was formed. However, whichever of the layer A and the layer B may be present on the substrate side, there is slight difference in the properties therebetween.

[0061] The thickness of the layer A, the thickness of the layer B and the number of times of laminating in the multilayer film were adjusted by varying the rotation speed of the table. That is, when the rotation speed is increased, the thickness of the layer A and the thickness of the layer B are decreased, and the number of times of laminating is increased. When the rotation speed is decreased, the thickness of the layer A and the thickness of the layer B are increased, and the number of times of laminating is decreased. As shown in test Nos. 1 to 4 in Table 1 as comparative examples, various monolayer films were also formed in accordance with ordinary procedures.

[0062] As for the resulting cemented carbide balls coated with various films, a sliding test was performed under the following conditions to evaluate the wear resistance of the films. At this time, an alumina plate was used as the following plate in place of a steel plate having scales. The diameter of a worn pan of the ball was measured, and the area corresponding to the diameter was evaluated as the wear amount. The case where the wear amount was 0.4 μm.sup.2 or less was evaluated as excellent in the wear resistance.

Sliding Test Conditions

[0063] Test Method: ball-on-plate type reciprocating sliding

[0064] Ball: cemented carbide balls coated with various films

[0065] Plate: an alumina plate

[0066] Vertical Load: 5N

[0067] Sliding Speed: 0.1 m/sec

[0068] Sliding Amplitude: 30 mm

[0069] Sliding Distance: 72 m

[0070] Temperature: room temperature

[0071] Also, as for respective hard film coating members, a scratch test was performed under the following conditions to evaluate the toughness of the films. At this time, the critical load at which chipping occurred in the film was measured, while increasing the pressing load of an indenter from a load of 0 N to a load of 100 N at the following load increase rate. The case where the critical load measured value was 70 N or more was evaluated as excellent in the toughness.

Scratch Test Conditions

[0072] Indenter: a diamond indenter whose tip has a radius of curvature of 200 μm

[0073] Load Increase Rate: 100 N/min

[0074] Maximum Load: 100 N

[0075] Indenter Moving Speed: 10 mm/min

[0076] Temperature: room temperature

[0077] These evaluation results are shown in the following Table 2.

TABLE-US-00002 TABLE 2 Test Scratch Critical Wear Amount No. Load (N) (μm.sup.2) 1 60 1.00 2 100 0.70 3 60 1.00 4 60 0.60 5 80 0.60 6 80 0.30 7 100 0.10 8 100 0.12 9 100 0.15 10 100 0.15 11 70 0.40 12 70 0.70 13 80 0.60 14 100 0.07 15 80 0.10 16 90 0.15 17 50 0.30 18 80 0.08 19 80 0.60 20 100 0.08 71 100 0.70 22 100 0.08 93 100 0.06 74 100 0.09 25 100 0.06 26 70 0.60 27 80 0.08 28 100 0.05 29 100 0.12 30 100 0.08 31 70 0.70 32 90 0.10

[0078] From these results, consideration can be made as follows. In test Nos. 6 to 11, 14 to 16, 18, 20, 22 to 25, 27 to 30 and 32, the compositions of the layers A and the layers B satisfy the range specified in the present invention. Therefore, it is found that good wear resistance and toughness are exerted.

[0079] In contrast, test Nos. Ito 5, 12, 13, 17, 19, 21, 26 and 31 do not satisfy any one of the requirements specified in the present invention, and at least either of the wear resistance and the toughness is deteriorated. That is, test No. I is a conventional TiN monolayer film, and both the wear resistance and the toughness are deteriorated. Test No. 2 is a conventional CrN monolayer film, and the wear resistance is deteriorated.

[0080] Test Nos. 3 and 4 are examples of forming a monolayer type film formed of only the layer A, and both the wear resistance and the toughness are deteriorated. Test No. 5 is an example in which the layer A and the layer B are thin in thickness, and the wear resistance is deteriorated.

[0081] Test No. 12 is an example in which the layer A and the layer B are thick in thickness, and the wear resistance is deteriorated. Test No. 13 is an example in which the Al amount in the layers A is insufficient, and the wear resistance is deteriorated. Test No. 17 is an example in which the Al amount in the layers A is excessive, and the toughness is deteriorated. Test No. 19 is an example in which the Al amount in the layers A is insufficient and the Si amount is excessive, and the wear resistance is deteriorated.

[0082] Test No. 21 is an example in which the Ti amount in the layers A is excessive and the Al amount is insufficient, and the wear resistance is deteriorated. Test No. 26 is an example in which the Cr amount in the layers B is small and the Si amount is excessive, and the wear resistance is deteriorated. Test No. 31 is an example in which the Al amount in the layers B is small and the Si amount is excessive, and the wear resistance is deteriorated.

[0083] In this example, the sliding test and the scratch test were performed at room temperature to evaluate the wear resistance and the toughness of the films. However, it is considered that even when the temperature is increased, for example, to such a high temperature as about 400 to 500° C., the results are hardly influenced thereby. Therefore, the film of the present invention is excellent also in the properties at the above high temperature.

Example 2

[0084] Laminated films having compositions shown in the following Table 3 were formed in the same manner as in Example 1. In all examples of the following Table 3, CrN films having a thickness of 5 .sub.lam were formed as intermediate layers prior to the formation of the films. The film of No. 7 in Table 3 is the same as the film of No. 22 in Table 1. Further, the film of No. 10 in Table 3 is the same as the film of No. 27 in Table 1, the film of No. 12 in Table 3 is the same as the film of No. 28 in Table 1, the film of No. 14 in Table 3 is the same as the film of No. 25 in Table 1, and the film of No, 16 in Table 3 is the same as the film of No. 30 in Table 1.

[0085] The total Al atomic ratios of the resulting various films were determined from the compositions of the respective layers, lattice constants shown in Table 3 and thicknesses of the respective layers by the method described above. The total Al atomic ratios are shown in Table 3. In addition, as for the resulting cemented carbide balls coated with various films, the sliding test was performed in the same manner as in Example 1 to evaluate the wear resistance of the films. Furthermore, as for respective hard film coating members, the scratch test was performed in the same manner as in Example 1 to evaluate the toughness of the films. These results are shown in Table 4.

TABLE-US-00003 TABLE 3 Number of Layer A Layer B Times Layer Compo- Lattice Layer Total of Lattice Thick- sition Con- Thick- Al Lami- Test Composition Constant ness (Atomic stant ness Atomic nating No. (Atomic Ratio) (nm) (nm) Ratio) (nm) (nm) Ratio (times) 1 (Al.sub.0.7Cr.sub.0.3)N 0.4126 70 CrN 0.414 5 0.56 200 2 (Al.sub.0.7Cr.sub.0.3)N 0.4126 20 CrN 0.414 10 0.47 167 3 (Al.sub.0.7Cr.sub.0.3)N 0.4126 20 CrN 0.414 20 0.35 125 4 (Al.sub.0.7Cr.sub.0.3)N 0.4126 20 CrN 0.414 40 0.23 83 5 (Al.sub.0.5Cr.sub.0.5)N 0.413 20 CrN 0.414 10 0.33 167 6 (Al.sub.0.5Cr.sub.0.5)N 0.413 10 CrN 0.414 5 0.33 333 7 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.40 0.43386 10 CrN 0.414 10 0.24 250 Si.sub.0.05)N 8 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.40 0.43386 10 CrN 0.414 5 0.33 333 Si.sub.0.05)N 9 (Ti.sub.0.03Al.sub.0.52Cr.sub.0.40 0.43386 20 CrN 0.414 5 0.40 200 Si.sub.0.05)N 10 (Ti.sub.0.03Zr.sub.0.02Al.sub.0.5 0.41416 10 CrN 0.414 10 0.25 250 Cr.sub.0.45)N 11 (Ti.sub.0.03Zr.sub.0.02Al.sub.0.5 0.41416 20 CrN 0.414 10 0.33 167 Cr.sub.0.45)N 12 (Zr.sub.0.05Al.sub.0.5Cr.sub.0.45)N 0.41515 10 CrN 0.414 10 0.25 250 13 (Zr.sub.0.05Al.sub.0.5Cr.sub.0.45)N 0.41515 20 CrN 0.414 5 0.40 200 14 (Al.sub.0.5Cr.sub.0.5)N 0.413 10 (Cr.sub.0.95Si.sub.0.05)N 0.414 10 0.25 250 15 (Al.sub.0.5Cr.sub.0.5)N 0.413 20 (Cr.sub.0.9Si.sub.0.1N 0.414 10 0.33 167 16 (Al.sub.0.5Cr.sub.0.5)N 0.413 10 (Al.sub.0.95Si.sub.0.05)N 0.412 10 0.25 250 17 (Al.sub.0.5Cr.sub.0.5)N 0.413 10 (Al.sub.0.95Si.sub.0.05)N 0.412 5 0.33 333

TABLE-US-00004 TABLE 4 Test Scratch Critical Wear Amount No. Load (N) (μm.sup.2) 1 90 0.15 2 100 0.05 3 100 0.04 4 80 0.2 5 90 0.05 6 90 0.05 7 100 0.08 8 100 0.05 9 100 0.04 10 80 0.12 11 80 0.06 12 100 0.13 13 100 0.05 14 100 0.14 15 100 0.04 16 100 0.08 17 100 0.05

[0086] From the results of Table 3 and Table 4, consideration can be made as follows. As for all of Nos. 1 to 17 in Table 3, the ratios of the elements in each layer of the layers A and the layers B are within the specified ranges, and the total Al atomic ratio is within the preferred range. As a result, it is found that good wear resistance and toughness are exerted. The total Al atomic ratio is within the preferred range as described above, so that it is found that the wear amount is 0.20 μm.sup.2 or less, which shows good toughness. In particular, it is found that in the examples in which the total Al atomic ratio is within the range of 0.35 to 0.55, a wear amount of 0.10 μm.sup.2 or less can be achieved to show sufficiently excellent toughness.

[0087] Although the present invention has been described in detail with reference to the specific embodiments, it will be apparent to those skilled in the art that various variations and modifications can be made without departing from the spirit and scope of the present invention.

[0088] The present application is based on Japanese Patent Application No. 2014-193885 filed on Sep. 24, 2014 and Japanese Patent Application No. 2014-266487 filed on Dec. 26, 2014, the contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

[0089] A laminated hard film of the present invention is more enhanced in wear resistance and toughness, and is useful for a .sub.jig and tool or a molding die having an cemented carbide, a cermet, a high-speed tool steel, an alloy tool steel or the like as a substrate.