Friction reduced and wear resistant coating, preparation method thereof and piston ring

Abstract

Provided are a friction reduced and wear resistant coating, a preparation method thereof and a piston ring. The coating includes an adhesive layer, a transition layer, a gradient layer and a function layer in sequence. The gradient layer is a CrMo.sub.xN layer in which Mo content progressively increases. The function layer includes at least one cyclical layer. Each cyclical layer includes a first CrMo.sub.xN layer and a second CrMo.sub.xN layer in sequence from bottom to top. The Mo content of the first CrMo.sub.xN layer is lower than the Mo content of the second CrMo.sub.xN layer. The coating provided by the present invention has a friction coefficient of 0.3 to 0.45, 10% to 30% lower than a CrN coating, and has an overall hardness of up to 1400 HV to 2600 HV and a thickness of 80 μm, satisfying the required durability for the full lifecycle of the piston ring. The preparation process of the coating is simple and highly operable, and thus is convenient for industrialization.

Claims

1. A coating able to reduce friction and wear, wherein the coating is located on a surface of a substrate and the coating comprises an adhesive layer, a transition layer, a gradient layer and a function layer in sequence in a direction away from the surface of the substrate, wherein the gradient layer is a CrMo.sub.xN layer in which Mo content progressively increases from 2.0-3.0 wt % to 3.0-6.0 wt %; and the function layer comprises at least one cyclical layer, each cyclical layer comprises a first CrMo.sub.xN layer and a second CrMo.sub.xN layer in sequence from bottom to top, and a Mo content of the first CrMo.sub.xN layer is lower than a Mo content of the second CrMo.sub.xN layer.

2. The coating of claim 1, wherein the first CrMo.sub.xN layer has a Mo content of 3.0 wt % to 6.0 wt %; and the second CrMo.sub.xN layer has a Mo content of 10.0 wt % to 15.0 wt %.

3. The coating of claim 1, wherein the function layer comprises 4 to 20 cyclical layers.

4. The coating of any one of claim 1, wherein the adhesive layer is a Cr layer.

5. The coating of claim 1, wherein the transition layer is a CrN layer and/or a Cr2N layer.

6. The coating of claim 1, wherein the substrate is a piston ring made of steel and/or cast iron.

7. The coating of any one of claim 1, wherein the coating has a thickness of 10 μm to 80 μm.

8. The coating of claim 1, wherein the function layer has a thickness of 7.5 μm to 55 μm.

9. The coating of claim 1, wherein a ratio of the thickness of the second CrMo.sub.xN layer to that of the first CrMo.sub.xN layer is (2-3):1.

10. The coating of claim 1, wherein the adhesive layer has a thickness of 0.5 μm to 3 μm.

11. The coating of claim 1, wherein the transition layer has a thickness of 1 μm to 11 μm.

12. The coating of claim 1, wherein the gradient layer has a thickness of 1 μm to 11 μm.

13. A piston ring provided with the coating of claim 1.

14. A preparation method of the coating of claim 1, comprising the following steps: (1) cleaning the surface of the substrate to obtain a cleaned substrate; (2) depositing the adhesive layer on the surface of the substrate by using a multi-arc ion plating device; (3) depositing the transition layer on a surface of the adhesive layer by using the multi-arc ion plating device; (4) depositing the gradient layer on a surface of the transition layer by using the multi-arc ion plating device; and (5) depositing the at least one cyclical layer on a surface of the gradient layer by using the multi-arc ion plating device to form the function layer and obtain the coating.

15. The preparation method of claim 14, wherein the cleaning in the step (1) comprises the following steps: (a) degreasing the surface of the substrate, subjecting the surface of the substrate to ultrasonic cleaning, drying the substrate, loading the substrate into the multi-arc ion plating device, heating the substrate to 380° C. to 450° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; and (b) passing 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding and cleaning the surface of the substrate at a negative bias voltage of −800 V to −1200 V.

16. The preparation method of claim 14, wherein process conditions for the depositing the adhesive layer in the step (2) comprise: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 1 Pa to 2 Pa, and a negative bias voltage of −17 V to −23 V applied to the substrate; process conditions for the depositing the transition layer in the step (3) comprise: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 4 Pa to 6 Pa, and a negative bias voltage of −30 V to −40 V applied to the substrate; process conditions for the depositing the gradient layer in the step (4) comprise a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a progressively increased CrMo cathode current from 30 A to 45 A to 40 A to 55 A; and process conditions for the depositing the at least one cyclical layer in the step (5) comprise: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a CrMo cathode current of 40 A to 55 A, for depositing the first CrMoxN layer; and then a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a CrMo cathode current of 80 A to 95 A, for depositing the second CrMoxN layer.

17. The preparation method of claim 14, wherein the step (5) comprises depositing 4 to 20 cyclical layers.

18. The preparation method of claim 14, wherein total duration of deposition process of the step (2) to the step (5) is 8 h to 39 h.

19. The preparation method of claim 14, comprising the following steps: (1) cleaning the surface of the substrate to obtain the cleaned substrate, wherein the cleaning comprises: (a) degreasing the surface of the substrate, subjecting the surface of the substrate to ultrasonic cleaning, drying the substrate, loading the substrate into the multi-arc ion plating device, heating the substrate to 380° C. to 450° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; and (b) passing the 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding and cleaning the surface of the substrate at the negative bias voltage of −800 V to −1200 V; (2) depositing the adhesive layer, a Cr layer, on the surface of the substrate under the following process conditions: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 1 Pa to 2 Pa, and a negative bias voltage of −17 V to −23 V applied to the substrate; (3) depositing the transition layer, a CrN layer and/or a Cr.sub.2N layer, on the Cr layer under the following process conditions: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 4 Pa to 6 Pa, and a negative bias voltage of −30 V to −40 V applied to the substrate; (4) depositing the CrMo.sub.xN layer in which Mo content progressively increases under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a progressively increased CrMo cathode current from 30 A to 45 A to 40 A to 55A; (5) depositing the first CrMo.sub.xN layer under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a CrMo cathode current of 40 A to 55 A; and then depositing the second CrMo.sub.xN layer under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate, and a CrMo cathode current of 80 A to 95 A; and (6) repeating the step (5) for 4 to 20 cycles until the end of a process duration, and taking out the substrate after a furnace temperature is lower than 150° C., to obtain the coating on the surface of the substrate, wherein total duration of deposition process from the step (2) to the step (5) is 8 h to 39 h.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a structure diagram of a coating on the surface of a substrate according to an embodiment of the present disclosure. In FIG. 1, 1—substrate; 2—adhesive layer; 3—transition layer; 4—gradient layer; 5—first CrMo.sub.xN layer; 6—second CrMo.sub.xN layer; and 7—function layer.

(2) FIG. 2 is a graph showing the Cr content and the Mo content of each layer in a coating according to an embodiment of the present disclosure. In FIG. 2, the dashed line indicates the Cr content and the solid line indicates the Mo content.

DETAILED DESCRIPTION

(3) The present disclosure is further described below through embodiments with reference to drawings.

(4) In one embodiment, as shown in FIG. 1, the present disclosure provides a coating having a thickness of 10 μm to 80 μm, the coating includes an adhesive layer 2, a transition layer 3, a gradient layer 4 and a function layer 7 in sequence, and the adhesive layer 2 is in direct contact with the surface of a substrate 1.

(5) The adhesive layer 2 is a Cr layer and has a thickness of 0.5 μm to 3 μm.

(6) The transition layer 3 is a CrN layer and/or a Cr.sub.2N layer and has a thickness of 1 μm to 11 μm.

(7) The gradient layer 4 is a CrMo.sub.xN layer in which Mo content progressively increases. The gradient layer 4 has a thickness of 1 μm to 11 μm.

(8) The function layer 7 includes at least one cyclical layer (for example, 2, 3, 4, 5, 8, 10, 15, 20, 25, 30, 35 or 40 cyclical layers). FIG. 1 shows 4 cyclical layers. Each cyclical layer includes a first CrMo.sub.xN layer 5 and a second CrMo.sub.xN layer 6 coating on the surface of the first CrMo.sub.xN layer 5. The function layer 7 has a thickness of 7.5 μm to 55 μm. The ratio of the thickness of the second CrMo.sub.xN layer 6 to that of the first CrMo.sub.xN layer 5 is (2-3):1.

(9) The Mo content of the first CrMo.sub.xN layer 5 is lower than the Mo content of the second CrMo.sub.xN layer 6. The first CrMo.sub.xN layer 5 has Mo content of 3.0 wt % to 6.0 wt %. The second CrMo.sub.xN layer 6 has Mo content of 10.0 wt % to 15.0 wt %. The Cr content and the Mo content of the bonding layer 2, the transition layer 3, the gradient layer 4 and the function layer 7 vary as shown in FIG. 2.

(10) In another embodiment, the present disclosure provides a preparation method of the coating. The preparation method includes the steps described below:

(11) (1) cleaning the surface of the substrate 1 to obtain a cleaned substrate 1; the cleaning specifically comprising:

(12) (a) degreasing the surface of the substrate 1 and subjecting the surface of the substrate 1 to ultrasonic cleaning, drying the substrate 1 and loading the substrate 1 into a multi-arc ion plating device, heating the substrate 1 to 380° C. to 450° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; the substrate 1 may be a piston ring; and (b) passing 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding cleaning the surface of the piston ring at a negative bias voltage of 800 V to 1200 V;
(2) depositing the adhesive layer, a Cr layer on the surface of the substrate 1 under the following process conditions: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 1 Pa to 2 Pa, and a negative bias voltage of 17 V to 23 V applied to the substrate 1;
(3) depositing the transition layer, a CrN layer and/or a Cr.sub.2N layer on the Cr layer under the following process conditions: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 80 A to 120 A, a pressure of 4 Pa to 6 Pa, and a negative bias voltage of −30 V to −40 V applied to the substrate 1;
(4) depositing the CrMo.sub.xN layer in which Mo content progressively increases under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate 1, and a progressively increased CrMo cathode current from 30 A to 45 A to 40 A to 55 A;
(5) depositing the first CrMo.sub.xN layer 5 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate 1, and a CrMo cathode current of 40 A to 55 A; and then depositing the second CrMo.sub.xN layer 6 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4 Pa to 6 Pa, a negative bias voltage of −30 V to −40 V applied to the substrate 1, and a CrMo cathode current of 80 A to 95 A; and
(6) repeating the step (5) for 4 to 20 cycles until the end of the process duration, and taking the substrate 1 out after the furnace temperature is lower than 150° C. to obtain the coating on the surface of the substrate 1.

(13) Total duration of deposition process of the step (2) to the step (5) is 8 h to 39 h.

Embodiment One

(14) A coating on the surface of a piston ring is provided. The coating has a thickness of 10 μm. The coating includes an adhesive layer 2, a transition layer 3, a gradient layer 4 and a function layer 7 in sequence. The adhesive layer 2 is located on the surface of the piston ring.

(15) The adhesive layer 2 is a Cr layer and has a thickness of 0.5 μm.

(16) The transition layer 3 is a CrN layer and has a thickness of 1 μm.

(17) The gradient layer 4 is a CrMo.sub.xN layer in which Mo content progressively increases.

(18) The gradient layer 4 has a thickness of 1 μm.

(19) The function layer 7 (modulation structure) includes one cyclical layer. The cyclical layer includes a first CrMo.sub.xN layer 5 and a second CrMo.sub.xN layer 6 overlaying the surface of the first CrMo.sub.xN layer 5. The Mo content of the first CrMo.sub.xN layer 5 is lower than the Mo content of the second CrMo.sub.xN layer 6. The Mo content of the first CrMo.sub.xN layer 5 is 3.0 wt %. The Mo content of the second CrMo.sub.xN layer 6 is 10.0 wt %. The function layer 7 has a thickness of 7.5 μm. The ration of the thickness of the second CrMo.sub.xN layer 6 to that of the first CrMo.sub.xN layer 5 is 2:1.

(20) The preparation method of the coating includes the steps described below:

(21) (1) cleaning the surface of the substrate 1 to obtain a cleaned substrate 1; the cleaning specifically comprising:

(22) (a) degreasing the surface of the substrate 1 and subjecting the surface of the substrate 1 to ultrasonic cleaning, drying the substrate 1 and loading the substrate 1 into a multi-arc ion plating device, heating the substrate 1 to 390° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; wherein the substrate 1 is a piston ring; and (b) passing 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding and cleaning the surface of the piston ring at a negative bias voltage of 900 V;
(2) depositing the adhesive layer, a Cr layer, on the surface of the substrate 1 under the following process conditions: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 85 A, a pressure of 1.2 Pa, and a negative bias voltage of −19 V applied to the substrate 1;
(3) depositing the transition layer, a CrN layer, on the Cr layer under the following process conditions: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 85 A, a pressure of 4.2 Pa, and a negative bias voltage of 38 V applied to the substrate 1;
(4) depositing the CrMo.sub.xN layer in which Mo content progressively increases under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4.2 Pa, a negative bias voltage of 38 V applied to the substrate 1, and a progressively increased CrMo cathode current from 32 A to 42 A;
(5) depositing the first CrMo.sub.xN layer 5 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4.2 Pa, a negative bias voltage of −38 V applied to the substrate 1, and a CrMo cathode current of 43 A; and then depositing the second CrMo.sub.xN layer 6 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 4.2 Pa, a negative bias voltage of −38 V applied to the substrate 1, and a CrMo cathode current of 82 A; and
(6) taking the substrate 1 out after the furnace temperature is lower than 150° C. to obtain the coating on the surface of the substrate.

(23) Total duration of deposition process of the step (2) to the step (5) is 8.6 h.

(24) It is obtained from the testing of the hardness and friction coefficient of the prepared coating that the prepared coating has a friction coefficient of 0.35 and a hardness of 1800 to 1900.

Embodiment Two

(25) A coating on the surface of a piston ring is provided. The coating has a thickness of 80 μm. The coating includes an adhesive layer 2, a transition layer 3, a gradient layer 4 and a function layer 7 in sequence. The adhesive layer 2 is located on the surface of the piston ring.

(26) The adhesive layer 2 is a Cr layer and has a thickness of 3 μm.

(27) The transition layer 3 is a Cr.sub.2N layer and has a thickness of 11 μm.

(28) The gradient layer 4 is a CrMo.sub.xN layer in which Mo content progressively increases.

(29) The gradient layer 4 has a thickness of 11 μm.

(30) The function layer 7 (modulation structure) includes 20 cyclical layers. Each cyclical layer includes a first CrMo.sub.xN layer 5 and a second CrMo.sub.xN layer 6 overlaying the surface of the first CrMo.sub.xN layer 5. The Mo content of the first CrMo.sub.xN layer 5 is lower than the Mo content of the second CrMo.sub.xN layer 6. The Mo content of the first CrMo.sub.xN layer 5 is 6.0 wt %. The Mo content of the second CrMo.sub.xN layer 6 is 15.0 wt %. The function layer 7 has a thickness of 55 μm. The thickness ratio of the second CrMo.sub.xN layer 6 to the first CrMo.sub.xN layer 5 is 3:1.

(31) The preparation method of the coating includes the steps described below:

(32) (1) cleaning the surface of the substrate 1 to obtain a cleaned substrate 1; the cleaning specifically comprising:

(33) (a) degreasing the surface of the substrate 1 and subjecting the surface of the substrate 1 to ultrasonic cleaning, drying the substrate 1 and loading the substrate 1 into a multi-arc ion plating device, heating the substrate 1 to 435° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; wherein the substrate 1 is a piston ring. (b) passing 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding and cleaning the surface of the piston ring at a negative bias voltage of −1100V.
(2) depositing the adhesive layer, a Cr layer, on the surface of the substrate 1 under the following process conditions: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 110 A, a pressure of 1.5 Pa, and a negative bias voltage of −22 V applied to the substrate 1.
(3) depositing the transition layer, a Cr.sub.2N layer, on the Cr layer under the following process conditions: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 110 A, a pressure of 5 Pa, and a negative bias voltage of 38 V applied to the substrate 1.
(4) depositing the CrMo.sub.xN layer in which Mo content progressively increases under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5 Pa, a negative bias voltage of −38 V applied to the substrate 1, and a progressively increased CrMo cathode current from 35 A to 53 A.
(5) depositing the first CrMo.sub.xN layer 5 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5 Pa, a negative bias voltage of −38 V applied to the substrate 1, and a CrMo cathode current of 53 A; and then depositing the second CrMo.sub.xN layer 6 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5 Pa, a negative bias voltage of −38 V applied to the substrate 1, and a CrMo cathode current of 93 A.
(6) repeating the step (5) for 20 cycles until the end of the process duration, and taking the substrate 1 out after the furnace temperature is lower than 150° C. to obtain the coating on the surface of the substrate 1.

(34) Total duration of deposition process of the step (2) to the step (5) is 38 h.

(35) It is obtained from the testing of the hardness and friction coefficient of the prepared coating that the prepared coating has a friction coefficient of 0.4 and a hardness of 1800 to 1900.

Embodiment Three

(36) A coating on the surface of a piston ring is provided. The coating has a thickness of 60 μm. The coating includes an adhesive layer 2, a transition layer 3, a gradient layer 4 and a function layer 7 in sequence. The adhesive layer 2 is in direct contact with the surface of the substrate 1.

(37) The adhesive layer 2 is a Cr layer and has a thickness of 2 μm.

(38) The transition layer 3 is a CrN layer and has a thickness of 5 μm.

(39) The gradient layer 4 is a CrMo.sub.xN layer in which Mo content progressively increases. The gradient layer 4 has a thickness of 5 μm.

(40) The function layer 7 (modulation structure) includes 4 cyclical layers. Each cyclical layer includes a first CrMo.sub.xN layer 5 and a second CrMo.sub.xN layer 6 overlaying the surface of the first CrMo.sub.xN layer 5. The Mo content of the first CrMo.sub.xN layer 5 is lower than the Mo content of the second CrMo.sub.xN layer 6. The Mo content of the first CrMo.sub.xN layer 5 is 5.0 wt %. The Mo content of the second CrMo.sub.xN layer 6 is 12.0 wt %. The function layer 7 has a thickness of 48 μm. The thickness ratio of the second CrMo.sub.xN layer 6 to the first CrMo.sub.xN layer 5 is 2.5:1.

(41) The preparation method of the coating includes the steps described below:

(42) (1) cleaning the surface of the substrate 1 is cleaned to obtain a cleaned substrate 1; the clean specifically comprising:

(43) (a) degreasing the surface of the substrate 1 and subjecting the surface of the substrate 1 to ultrasonic cleaning, drying the substrate 1 and loading the substrate 1 into a multi-arc ion plating device, heating the substrate 1 to 420° C., and then vacuumizing the multi-arc ion plating device to below 5.0×10.sup.−3 Pa; wherein the substrate 1 is a piston ring; and (b) passing 99.99% pure Ar to the multi-arc ion plating device, letting Ar ions bombarding and cleaning the surface of the piston ring at a negative bias voltage of −1,000 V;
(2) depositing the adhesive layer, a Cr layer, on the surface of the substrate 1 under the following process conditions: a metal Cr target as a cathode, Ar as a working reactant gas, a cathode current of 100 A, a pressure of 1.7 Pa, and a negative bias voltage of −20 V applied to the substrate 1;
(3) depositing the transition layer, a CrN layer, on the Cr layer under the following process conditions: a metal Cr target as a cathode, N.sub.2 as a working reactant gas, a cathode current of 100 A, a pressure of 5.2 Pa, and a negative bias voltage of −35V applied to the substrate 1;
(4) depositing the CrMo.sub.xN layer in which Mo content progressively increases under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5.2 Pa, a negative bias voltage of −35 V applied to the substrate 1, and a progressively increased CrMo cathode current from 33 A to 49 A;
(5) depositing the first CrMo.sub.xN layer 5 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5.2 Pa, a negative bias voltage of 35 V applied to the substrate 1, and a CrMo cathode current of 50 A; and then depositing the second CrMo.sub.xN layer 6 under the following process conditions: a metal Cr target and a metal CrMo target as a cathode, N.sub.2 as a working reactant gas, a pressure of 5.2 Pa, a negative bias voltage of −35 V applied to the substrate 1, and a CrMo cathode current of 89 A; and
(6) repeating the step (5) for 4 cycles until the end of the process duration, and taking the substrate 1 out after the furnace temperature is lower than 150° C. to obtain the coating on the surface of the substrate 1.

(44) Total duration of deposition process of the step (2) to the step (5) is 30 h.

(45) It is obtained from the testing of the hardness and friction coefficient of the prepared coating that the prepared coating has a friction coefficient of 0.32 and a hardness of 1800 to 1900.

(46) Applicants state that the above are only embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto. Those skilled in the art will appreciate that any variation or substitution that is easily conceivable within the technical scope of the present disclosure by those skilled in the art falls within the scope of the present disclosure.