Multilayer multi-element composite hard pvd coating on the surface of a piston ring, a piston ring and a preparation process

Abstract

The invention relates to a multilayer multi-element composite hard PVD coating with low friction coefficient on the surface of a piston ring, a piston ring and a preparation process. The present invention employs vacuum multi-arc ion plating vapor deposition process, which uses multiple multi-arc ion sources, in the combination of equipping with different single metal target material and multi-element target material to deposit multilayer multi-element composite hard PVD coating with low friction coefficient on the surface of a steel or cast iron piston ring. The coating consists of five layers with the total thickness of up to 60 m. The coating has high adhesion with the surface of piston ring, high hardness, low friction coefficient and good abrasion resistance. By controlling the adding amount of additive elements Al, Mo, W, B, Si and Ti, the friction coefficient of the coating can be further reduced 5 to 20% compared with that of a single TiN or CrN deposited layer.

Claims

1. A multilayer multi-element composite hard PVD coating for use on a surface of a piston ring, comprising a low friction coefficient and being applied by physical vapor deposition, wherein the coating consists of, from a bottom to a top, a single metal adhesion underlayer, a single nitride ramping layer that has a nitrogen content that increases from the bottom to the top of the layer, a single nitride deposited layer, a multi-element nitride ramping layer with increasing metal content, and a multi-element nitride deposited layer; wherein: the single metal adhesion underlayer is Cr, the single nitride deposited layer is CrN, the multi-element nitride deposited layer is Cr(Me)N, Me is selected from the group consisting of Mo, W, and B; and the friction coefficient of the coating is further reduced by 5 to 20% compared with the single nitride deposited layer.

2. The coating according to claim 1, wherein the single metal adhesion underlayer has a thickness of 1-4 m; the single nitride ramping layer has a thickness of 1-6 m; the single nitride deposited layer has a thickness of 5-20 m; the multi-element nitride ramping layer has a thickness of 2-10 m; the multi-nitride deposited layer has a thickness of 5-20 m; and a total thickness of the coating is within the range of 14-60 m.

3. A piston ring with the multilayer multi-element composite hard PVD coating according to claim 1 on a surface thereof.

4. The piston ring according to claim 3, wherein the surface of the piston ring is subjected to a nitriding treatment.

5. A process of preparing the multilayer multi-element composite hard PVD coating according to claim 1 on a surface of a piston ring, wherein the process is conducted in a PVD vacuum deposition device having a vacuum chamber and comprises the following steps: (1) subjecting the surface of a piston ring to plasma cleaning or other cleaning treatments; (2) igniting single metal target material cathodes to generate cold field induced arc discharge and depositing the single metal adhesion underlayer on the surface of the piston rings; (3) gradually introducing nitrogen gas; depositing the single nitride ramping layer with increasing nitrogen content on the single metal underlayer; and subsequently depositing the single nitride deposited layer; and (4) igniting multi-element target material cathodes, gradually increasing a current applied to the multi-element target material cathodes, depositing a multi-element nitride ramping layer with increasing metal content on the single nitride deposited layer, and depositing the multi-element nitride deposited layer with such having a constant amount of different elements.

6. The process according to claim 5, wherein during step (2), a vacuum degree in the vacuum chamber is controlled within 1.02-1.38 Pa, and a bias voltage of the piston ring is adjusted to between 17 and 23 V.

7. The process according to claim 5, wherein at the end of step (3) the nitrogen gas is purged, and a bias voltage of the piston ring is adjusted to between 30 and 40V.

8. The process according to claim 5, wherein the single nitride ramping layer is deposited until the single nitride deposited layer begins to be deposited and after a vacuum degree is kept within 4-6 Pa.

9. The process according to claim 5, wherein in step (4), a cathode current of the multi-element target cathodes is increased to 60-80 A, and then the cathode current is maintained and the multi-element nitride deposited layer is deposited.

10. The process according to claim 5, wherein the process is ended after 5-20 hours of deposition.

11. The process according to claim 5, wherein after step 4 the piston ring is cooled to lower than 150 C. and the vacuum chamber is opened to remove the piston ring out of the PVD vacuum deposition device.

12. The process according to claim 5, wherein, before step (1), a nitriding treatment and a subsequent surface grinding treatment are conducted; or a surface grinding treatment is conducted without a nitriding treatment, in order to remove a non-porous microstructure to ensure adhesion of the coating.

13. The process according to claim 5, wherein the multielement target material is selected from CrMo, CrW, and CrB.

14. The process according to claim 13, wherein, the amount of Mo, W, or B in the multi-element target material is 5-50% atm.

15. The process according to claim 5, wherein a number ratio of the single metal target material cathodes to the multi-element target material cathodes is 2:3 or 3:2.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 shows the structure diagram of a multilayer multi-element composite hard PVD coating on the surface of a piston ring according to the present invention.

(2) FIG. 2 shows a top view of the target site distribution of a multi-arc ion deposited layer device.

(3) FIG. 3 shows the SEM morphology of a section of a CrMoN deposited layer.

(4) FIG. 4 is shows the line scanning result of each element (N, Mo, Cr or Fe) of a section of a CrMoN deposited layer.

(5) FIG. 5 shows the friction coefficient curve of a CrMoN deposited layer.

(6) Wherein:

(7) 1single metal underlayer; 2single nitride ramping layer; 3single nitride deposited layer; 4multi-element nitride ramping layer; 5multi-element nitride deposited layer; 6cathode and multi-element alloy target material; 7piston ring; 8cathode and single element target material; 9rotary clamp; 10vacuum chamber.

(8) Hereinafter, the present invention is further described in details. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope claimed by the present invention. The protection scope of the invention prevails in the claims.

DETAILED DESCRIPTION

(9) Hereinafter, the solutions of the present invention are further explained through the specific embodiments referring to the drawings. As used in the description and throughout the claims, the meaning of a, an, and the includes plural reference unless the context clearly dictates otherwise. Also, as used in the description and throughout the claims, the meaning of in includes in and on unless the context clearly dictates otherwise.

(10) To better explain the invention and help the understanding of the solutions of the invention, typical but non-limiting examples are described as follows.

(11) As shown in FIG. 1, a multi-layer multi-element composite hard PVD coating on the surface of a piston ring consists of, from the bottom to the top, a single metal adhesion underlayer 1, a single nitride ramping layer 2, a single nitride deposited layer 3, a multi-element nitride ramping layer 4 and a multi-element nitride deposited layer 5.

(12) As shown in FIG. 2, on the chamber body of the production apparatus for the multilayer multi-element composite hard PVD coating is mounted single metal target material, Cr target material, and binary target material, CrMo target material. The multi-arc ion deposited apparatus comprises a vacuum chamber 10, a rotating clamp 9, a piston ring 7, cathode and multi-element alloy target material 6, cathode and single element target material 8.

Example 1

(13) A multilayer multi-element composite hard PVD coating on the surface of a piston ring, consists of, from the bottom to the top, a Cr metal underlayer, a CrN ramping layer, a CrN deposited layer, a Cr(Mo)N ramping layer and a Cr(Mo)N deposited layer. The Cr metal underlayer has a thickness of 4 m. The CrN ramping layer has a thickness of 6 m. The CrN deposited layer has a thickness of 20 m. The Cr (Mo) N ramping layer has a thickness of 10 m. The Cr (Mo) N deposited layer has a thickness of 20 m. The total thickness of the coating is 60 m.

(14) The present example provides a piston ring with the multilayer multi-element composite hard PVD coating, wherein the surface of the piston ring is not subjected to nitriding treatment.

(15) The preparation process of the multilayer multi-element composite hard PVD coating on the surface of the piston ring is conducted in a PVD vacuum deposited apparatus, and comprises the following steps:

(16) (1) subjecting the surface of a piston ring to plasma cleaning or other cleaning treatments; after the piston ring to be plated is subjected to the degreasing, rinsing, dehydration, wind shear and drying treatments, the piston ring is mounted on the piston ring specific planetary rotating stand, to ensure the work face of the piston ring is the plated face. Vacuum is pumped and the heater in the vacuum chamber is started to heat the chamber to 400-450 C., the planetary rotating system is started at the same time to ensure the gas and vapor etc. remained on the surface of the piston ring to be timely discharged, till the vacuum degree is pumped to 510.sup.3 Pa. Argon is purged and a bias voltage of 900V is applied on the piston ring for ion etching on it, thereby a metal ion flow with high energy density will further sputter down the residual gas contaminants etc. on the surface of the piston ring, sufficiently purifying the plated face of the piston ring;

(17) (2) controlling the vacuum degree in the vacuum chamber at 1.2 Pa, adjusting the bias voltage of the piston ring to 20V, igniting Cr target material cathodes to generate cold field induced arc discharge and depositing a Cr metal underlayer on the surface of the piston ring;

(18) (3) gradually introducing nitrogen gas, adjusting the bias voltage of the piston ring to 35V, depositing a CrN ramping layer with various nitrogen content on the Cr metal underlayer till depositing a uniform CrN deposited layer as the vacuum degree is maintained at 5 Pa;

(19) (4) igniting CrMo target material cathodes, gradually increasing cathode current and depositing a Cr (Mo) N ramping layer with increasing metal content on the CrN deposited layer; when the cathode current is increased to 75 A, maintaining the cathode current and depositing a uniform Cr(Mo)N deposited layer;

(20) (5) ending the process after 20 h deposition; turning off the gas supply system, cathode system, bias voltage system, etc.; after the piston ring is cooled to below 150 C., opening the vacuum chamber and removing the piston ring out of the system.

(21) The adding amount of Mo element in the CrMo target material is 5% atm.

(22) The number ratio of the cathode arc sources of the Cr metal target material to those of the CrMo target material is 2:3.

Example 2

(23) A multilayer multi-element composite hard PVD coating on the surface of a piston ring, consists of, from the bottom to the top, a Cr metal underlayer, a CrN ramping layer, a CrN deposited layer, a Cr(Si)N ramping layer and a Cr(Si)N deposited layer. The Cr metal underlayer has a thickness of 1 m. The CrN ramping layer has a thickness of 1 m. The CrN deposited layer has a thickness of 5 m. The Cr(Si)N ramping layer has a thickness of 2 m. The Cr(Si)N deposited layer has a thickness of 5 m. The total thickness of the coating is 14 m.

(24) The present example provides a piston ring with the multilayer multi-element composite hard PVD coating, wherein the surface of the piston ring is subjected to nitriding treatment.

(25) The preparation process of the multilayer multi-element composite hard PVD coating on the surface of the piston ring is conducted in a PVD vacuum deposited apparatus, and comprises the following steps:

(26) (1) subjecting the as-received surface of a piston ring to nitriding treatment;

(27) (2) conducting purification treatment as described in EXAMPLE 1;

(28) (3) controlling the vacuum degree in the vacuum chamber at 1.02 Pa, adjusting the bias voltage of the piston ring to 17V, igniting Cr target material cathodes to generate cold field induced arc discharge and depositing a Cr metal underlayer on the surface of the piston ring;

(29) (4) gradually introducing nitrogen gas, adjusting the bias voltage of the piston ring to 40V, depositing a CrN ramping layer with various nitrogen content on the Cr metal underlayer till depositing a uniform CrN deposited layer as the vacuum degree is maintained at 4 Pa;

(30) (5) igniting CrSi target material cathodes, gradually increasing cathode current and depositing a Cr(Si)N ramping layer with increasing metal content on the CrN deposited layer; when the cathode current is increased to 60 A, maintaining the cathode current and depositing a uniform Cr(Si)N deposited layer;

(31) (6) ending the process after 5 h deposition; turning off the gas supply system, cathode system, bias voltage system, etc.; after the piston ring is cooled to below 150 C., opening the vacuum chamber and removing the piston ring out of the system.

(32) The adding amount of Si element in the CrSi target material is 50% atm.

(33) The number ratio of the cathode arc sources of the Cr metal target material to those of the CrSi target material is 3:2.

Example 3

(34) A multilayer multi-element composite hard PVD coating on the surface of a piston ring, consists of, from the bottom to the top, a Cr metal underlayer, a CrN ramping layer, a CrN deposited layer, a Cr(Me)N ramping layer and a Cr(Me)N deposited layer. Said Me is the combination of W and B. The Cr metal underlayer has a thickness of 3 m. The CrN ramping layer has a thickness of 4 m. The CrN deposited layer has a thickness of 16 m. The Cr(Me)N ramping layer has a thickness of 8 m. The Cr(Me)N deposited layer has a thickness of 19 m. The total thickness of the coating is 50 m.

(35) The present example provides a piston ring with the multilayer multi-element composite hard PVD coating, wherein the surface of the piston ring is not subjected to nitriding treatment.

(36) The preparation process of the multilayer multi-element composite hard PVD coating on the surface of the piston ring is conducted in a PVD vacuum deposited apparatus, and comprises the following steps:

(37) (1) conducting purification treatment as described in EXAMPLE 1;

(38) (2) controlling the vacuum degree in the vacuum chamber at 1.38 Pa, adjusting the bias voltage of the piston ring to 23V, igniting Cr target material cathodes to generate cold field induced arc discharge and depositing a Cr metal underlayer on the surface of the piston ring;

(39) (3) gradually introducing nitrogen gas, adjusting the bias voltage of the piston ring to 30V, depositing a CrN ramping layer with various nitrogen content on the Cr metal underlayer till depositing a uniform CrN deposited layer as the vacuum degree is maintained at 6 Pa;

(40) (5) igniting CrMe target material cathodes, gradually increasing cathode current and depositing a Cr(Me)N ramping layer with increasing metal content on the CrN deposited layer; when the cathode current is increased to 80 A, maintaining the cathode current and depositing a uniform Cr(Me)N deposited layer;

(41) (6) ending the process after 17 h deposition; turning off the gas supply system, cathode system, bias voltage system, etc.; after the piston ring is cooled to below 150 C., opening the vacuum chamber and removing the piston ring.

(42) The adding amount of W and B elements in the CrMe target material is 30% atm.

(43) The number ratio of the cathode arc sources of the Cr metal target material to those of the CrMe target material is 3:2.

Example 4

(44) A multilayer multi-element composite hard PVD coating on the surface of a piston ring, consists of, from the bottom to the top, a Ti metal underlayer, a TiN ramping layer, a TiN deposited layer, a Ti(Me)N ramping layer and a Ti(Me)N deposited layer. Said Me is the combination of Si and Mo.

(45) The Ti metal underlayer has a thickness of 4 m. The TiN ramping layer has a thickness of 2 m. The TiN deposited layer has a thickness of 12 m. The Ti(Me)N ramping layer has a thickness of 6 m. The Ti(Me)N deposited layer has a thickness of 15 m. The total thickness of the coating is 39 m.

(46) The present example provides a piston ring with the multilayer multi-element composite hard PVD coating, wherein the surface of the piston ring is subjected to nitriding treatment.

(47) The preparation process of the multilayer multi-element composite hard PVD coating on the surface of the piston ring is conducted in a PVD vacuum deposited apparatus, and comprises the following steps:

(48) (1) subjecting the as-received surface of a piston ring to nitriding treatment;

(49) (2) conducting purification treatment as described in EXAMPLE 1;

(50) (3) controlling the vacuum degree in the vacuum chamber at 1.2 Pa, adjusting the bias voltage of the piston ring to 18V, igniting Ti target material cathodes to generate cold field induced arc discharge and depositing a Ti metal underlayer on the surface of the piston ring;

(51) (4) gradually introducing nitrogen gas, adjusting the bias voltage of the piston ring to 33V, depositing a TiN ramping layer with various nitrogen content on the Ti metal underlayer till depositing a uniform TiN deposited layer as the vacuum degree is maintained at 5 Pa;

(52) (5) igniting TiMe target material cathodes, gradually increasing cathode current and depositing a Ti(Me)N ramping layer with increasing metal content on the TiN deposited layer; when the cathode current is increased to 75 A, maintaining the cathode current and depositing a uniform Ti(Me)N deposited layer;

(53) (6) ending the process after 13 h deposition; turning off the gas supply system, cathode system, bias voltage system, etc.; after the piston ring is cooled to below 150 C., opening the vacuum chamber and removing the piston ring.

(54) The adding amount of Si and Mo elements in the TiMe target material is 20% atm.

(55) The number ratio of the cathode arc sources of the Ti metal target material to those of the TiMe target material is 2:3.

(56) The applicant states that the present invention to describe the detailed structure features and preparation method of the present invention via the above examples, but the present invention is not limited to the above detailed structure features and preparation method, i.e. the present invention does not have to rely on the above detailed structure features and preparation method to implement. A person skilled in the art would understand, any modification of the present invention, the equivalent replacement to the elements used in the present invention, the addition of an auxiliary ingredient, the selection of a specific mode, etc. all fall within the protection and disclosure scope of the present invention.

(57) The preferred embodiment of the present invention is described in details in above, but the present invention is not limited to the specific details of the above embodiment. Within the technical conceptive scope of the present invention, various simple changes can be made to the technical solutions of the present invention, and all the simple changes belong to the protection scope of the present invention.

(58) In addition, it should be noted that in the case of not contradictory, each specific technical feature of the above embodiments may be combined in any suitable manner. To avoid unnecessary repetition, the present invention does not provide further description for the various possible combinations.

(59) Moreover, the various embodiments of the present invention can also be combined arbitrarily, as long as the combinations does not deviate from the spirit of the invention and they should also be considered as the disclosure of the present invention.