Anti-ablation wear-resistant antifriction coating piston ring, preparation method and engine

Abstract

The invention belongs to the technical field of piston ring coatings, and discloses an anti-ablation wear-resistant antifriction coating piston ring, a preparation method and an engine. The outer circle face of the piston ring base body comprises a wear-resisting and friction-reducing layer and a protective layer from bottom to top, and the protective layer is a single nitride layer or a multi-element nitride layer. The wear-resistant antifriction layer and the protective layer are applied to the piston ring from bottom to top, the piston ring is installed in an engine and makes contact with the protective layer on the surface when high-temperature and high-pressure airflow impacts the piston ring, the internal DLC functional layer is completely wrapped and protected by the protective layer on the outer layer, and the protective layer has higher ablation resistance than the DLC layer; and phase transformation of the internal DLC layer is effectively avoided. Chromium nitride can be oxidized in a high-temperature environment of 600 DEG C or above generally, and the physical characteristics of chromium nitride cannot be changed at the temperature lower than the high-temperature environment; elements are doped in the doped multi-element nitride, so that the mechanical property is improved, and the high temperature resistance is also achieved.

Description

Technical Field

[0001] The invention relates to the technical field of piston ring coatings, and in particular to an ablation-resistant, wear-resistant, and friction-reducing coating piston ring, a preparation method thereof, and an engine. Background Art

[0002] The cylinder liner-piston ring friction pair is one of the most important friction pairs in the internal combustion engine. Its lubrication and friction performance directly affects the fuel economy, thermal efficiency, durability and even the life of the whole engine. The main functions of the piston ring include sealing, oil control, heat transfer and support, which directly affect the performance, working reliability, oil consumption rate and service life of the engine. Among them, the piston is directly subjected to the impact of high-temperature and high-pressure airflow when working, and 60-75% of the heat absorbed by the engine piston group is dissipated by the ring belt.

[0003] As internal combustion engines develop towards high power density, the explosion pressure, temperature in the combustion chamber and the back pressure on the piston ring also increase accordingly, causing the lubrication conditions of the cylinder liner-piston ring friction pair to become more stringent than before. The piston ring operates in high-temperature and high-pressure gas, the temperature rises, and the quality of the engine oil decreases, which greatly reduces the original lubrication effect and accelerates the wear process.

[0004] There are currently a number of technologies that can improve the tribological properties of piston rings. The most effective surface treatment method is to deposit a diamond-like carbon-based coating (DLC coating) on ​​the outer cylindrical surface. The high hardness and self-lubricating properties of the DLC coating make the piston ring exhibit excellent wear resistance, low friction performance, and low attack performance on the wear cylinder liner. On the other hand, the DLC coating is a metastable amorphous material containing a diamond structure (sp3 bond) and a graphite structure (sp2 bond). The carbon atoms are mainly combined with sp3 and sp2 hybrid bonds. Under high temperature and high pressure conditions, it is very easy to undergo irreversible changes (ordering), that is, gradually changing from a diamond-like structure to a graphite-like structure. The corresponding performance of the coating will be greatly reduced or even fail. In particular, the area near the opening of the first piston ring is subjected to the highest temperature airflow impact. Therefore, the DLC coating at its opening is very likely to undergo structural changes under the impact of high temperature and high pressure airflow, and "ablation" occurs.

[0005] Patent CN101680078A discloses a chromium nitride ion plating coating used on a piston ring of a diesel engine, the main components of which are chromium, nitrogen and carbon, and the carbon concentration is 4 to 8 weight % relative to the sum of the concentrations of these components, the orientation of the CrN (111) surface is 0.4 to 0.8 according to the CrN (111) structure coefficient, and the Vickers hardness is HV1600 to HV2000. Although the coating also exhibits good wear resistance and ablation resistance, it mainly suppresses the formation of a coarse columnar crystal structure by adding carbon, solving the problem of defective peeling of the chromium nitride coating. However, it is a consensus that the chromium nitride ion plating coating is not as good as the DLC coating in terms of wear resistance and low friction performance.

[0006] Therefore, how to make the coating have anti-ablation performance, wear resistance and low friction performance at the same time is an urgent problem to be solved. Summary of the invention

[0007] The purpose of the present invention is to provide an anti-ablation wear-resistant and friction-reducing coating piston ring and a preparation method and an engine, so as to solve the problem that the existing piston ring coating cannot take into account both anti-ablation performance and wear resistance and low friction performance.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides an anti-ablation wear-resistant and friction-reducing coating piston ring, wherein the outer circumferential surface of the piston ring substrate comprises a wear-resistant and friction-reducing layer and a protective layer from bottom to top;

[0010] The wear-resistant and friction-reducing layers are, from bottom to top, a first primer layer, a second primer layer, a gradient DLC layer, and a DLC functional layer;

[0011] The protective layer is a single nitride layer or a multi-nitride layer.

[0012] Preferably, the thickness of the wear-resistant and friction-reducing layer is 10 to 23 μm; and the thickness of the protective layer is 1 to 5 μm.

[0013] Preferably, the single nitride layer is a chromium nitride layer; the multi-nitride layer is a Cr(Me)N layer, wherein Me is one or more of Al, Mo, W, B, Si, and Ti.

[0014] Preferably, the first primer layer is a chromium layer; and the second primer layer is a titanium layer.

[0015] The present invention also provides a method for preparing an ablation-resistant wear-resistant and friction-reducing coating piston ring, comprising the following steps:

[0016] (1) placing the piston ring substrate in a vacuum coating device, heating and evacuating the cavity of the vacuum coating device; then introducing argon gas, using the outer cylindrical surface of the piston ring substrate as the coating surface, and performing ion cleaning on the outer cylindrical surface;

[0017] (2) using a chromium target as a cathode and argon as a reaction gas to deposit a first primer layer on the outer cylindrical surface after ion cleaning;

[0018] (3) turning off the chromium target, using the titanium target as a magnetron sputtering target and argon as a reaction gas to deposit a second base layer on the first base layer;

[0019] (4) Turn off the titanium target, use the graphite target as the cathode, use argon as the reaction gas, gradually increase the negative bias voltage during the deposition process, and deposit a gradient DLC layer on the second base layer;

[0020] (5) Using the graphite target as the cathode, applying a high / low negative bias voltage that changes periodically during the deposition process to deposit a DLC functional layer on the gradient DLC layer;

[0021] (6) The graphite target is turned off, and a chromium target or a multi-element alloy target is used as a cathode and nitrogen is used as a reaction gas to deposit a protective layer on the DLC functional layer, thereby obtaining the ablation-resistant, wear-resistant and friction-reducing coating piston ring.

[0022] Preferably, the parameters for depositing the first bottom layer in step (2) are: vacuum degree is 1×10 -3 Pa; cathode current is 80~120A; negative bias voltage is -17~-23V; gas pressure is 1~2Pa; deposition time is 55~75min;

[0023] The parameters for depositing the second bottom layer in step (3) are: vacuum degree is 1×10 -3 Pa; the power of magnetron sputtering is 5 to 10 kW; the negative bias voltage is -100 to -200 V; the gas pressure is 0.2 to 2 Pa; and the deposition time is 55 to 75 min.

[0024] Preferably, the parameters of the gradient DLC layer deposited in step (4) are: vacuum degree is 1×10 -3 Pa; cathode current is 80~180A; negative bias voltage is uniformly increased from -800V to -2000V during deposition time; deposition time is 50~80min.

[0025] Preferably, the parameters for depositing the DLC functional layer in step (5) are: vacuum degree is 1×10 -3Pa; cathode current is 80-180A; high / low negative bias voltage is applied alternatingly in a period of 2-3s; the high negative bias voltage in the high / low negative bias voltage is -1600-2500V; the low negative bias voltage in the high / low negative bias voltage is -600-1000V; the deposition time is 5-30h.

[0026] Preferably, the parameters for depositing the protective layer in step (6) are: nitrogen flow rate of 35 to 45 sccm; cathode current of 100 to 120 A; negative bias voltage of -20 to -25 V; and deposition time of 30 to 120 min.

[0027] The present invention also provides an engine, in which the erosion-resistant wear-resistant and friction-reducing coating piston ring or the erosion-resistant wear-resistant and friction-reducing coating piston ring prepared by the preparation method of the erosion-resistant wear-resistant and friction-reducing coating piston ring is adopted.

[0028] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0029] The piston ring of the present invention is applied with a wear-resistant and friction-reducing layer and a protective layer from bottom to top. When the high-temperature and high-pressure airflow inside the engine impacts the piston ring, the piston ring contacts the protective layer on the surface, while the internal DLC functional layer is completely "wrapped" and protected by the outer protective layer. The protective layer has higher ablation resistance than the DLC layer, and effectively avoids the phase transformation of the internal DLC layer. The chromium nitride used in the protective layer of the present invention will generally be oxidized in a high-temperature environment above 600°C, and its physical properties will not change below this temperature; and the doped elements in the multi-component nitride after doping improve the mechanical properties and also have high temperature resistance. Even if the piston ring of the present invention is worn on the surface after working for a period of time, the common biased barrel surface structure design of the piston ring means that the wear only occurs at the high point of the barrel surface of the outer circle of the piston ring. Even if the protective layer at the high point of the barrel surface is worn or even worn through (such as Figure 2 As shown in the figure, the protective layer at non-high point position (upper barrel surface and lower barrel surface of piston ring outer circle) can still withstand the impact of high temperature and high pressure airflow, effectively protect the internal DLC functional layer, and avoid "ablation" of wear-resistant and friction-reducing DLC ​​coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0031] Figure 1 It is a cross-sectional schematic diagram of the piston ring with ablation-resistant, wear-resistant and friction-reducing coating of the present invention;

[0032] Figure 2 It is a schematic cross-sectional view of the piston ring with the anti-ablation wear-resistant and anti-friction coating of the present invention after being worn;

[0033] Figure 3 The morphology of the wear-resistant and friction-reducing coating piston ring of Comparative Example 1 before and after the heat resistance test; wherein a is the morphology before the test, b is the morphology after the 300°C test, c is the morphology after the 350°C test, and d is the morphology after the 400°C test;

[0034] Figure 4 The morphology of the ablation-resistant wear-resistant and friction-reducing coating piston ring of Example 1 before and after the heat resistance test; wherein, a is the morphology before the test, b is the morphology after the 300°C test, c is the morphology after the 350°C test, and d is the morphology after the 400°C test;

[0035] Figure 5 The morphology of the ablation-resistant wear-resistant and friction-reducing coating piston ring of Example 2 before and after the heat resistance test; wherein, a is the morphology before the test, b is the morphology after the 300°C test, c is the morphology after the 350°C test, and d is the morphology after the 400°C test;

[0036] Figure 6 The morphology of the anti-ablation, wear-resistant and friction-reducing coating piston ring of Example 3 before and after the heat resistance test; wherein, a is the morphology before the test, b is the morphology after the 300°C test, c is the morphology after the 350°C test, and d is the morphology after the 400°C test. DETAILED DESCRIPTION

[0037] The present invention provides a piston ring with an anti-ablation wear-resistant and anti-friction coating, the cross-sectional schematic diagram of which is shown in FIG. Figure 1 As shown, the outer circumferential surface of the piston ring substrate includes a wear-resistant and friction-reducing layer and a protective layer from bottom to top;

[0038] The wear-resistant and friction-reducing layers are, from bottom to top, a first primer layer, a second primer layer, a gradient DLC layer, and a DLC functional layer;

[0039] The protective layer is a single nitride layer or a multi-nitride layer.

[0040] In the present invention, the thickness of the wear-resistant and friction-reducing layer is preferably 10 to 23 μm, more preferably 15 to 22 μm, and even more preferably 20 μm.

[0041] In the present invention, the thickness of the protective layer is preferably 1 to 5 μm, more preferably 2.5 to 4 μm, and even more preferably 3 μm.

[0042] In the present invention, the single nitride layer is preferably a chromium nitride layer; the multi-nitride layer is preferably a Cr(Me)N layer, wherein Me is preferably one or more of Al, Mo, W, B, Si, and Ti, further preferably one or more of Al, Mo, and Ti, and more preferably Mo.

[0043] In the present invention, the first primer layer is preferably a chromium layer; the second primer layer is preferably a titanium layer.

[0044] In the present invention, the DLC functional layer is a low-hardness DLC layer and a high-hardness DLC layer arranged alternately in sequence; the low-hardness DLC layer is adjacent to the gradient DLC layer.

[0045] In the present invention, the material of the piston ring substrate is preferably stainless steel.

[0046] The present invention also provides a method for preparing an ablation-resistant wear-resistant and friction-reducing coating piston ring, comprising the following steps:

[0047] (1) placing the piston ring substrate in a vacuum coating device, heating and evacuating the cavity of the vacuum coating device; then introducing argon gas, using the outer cylindrical surface of the piston ring substrate as the coating surface, and performing ion cleaning on the outer cylindrical surface;

[0048] (2) using a chromium target as a cathode and argon as a reaction gas to deposit a first primer layer on the outer cylindrical surface after ion cleaning;

[0049] (3) turning off the chromium target, using the titanium target as a magnetron sputtering target and argon as a reaction gas to deposit a second base layer on the first base layer;

[0050] (4) Turn off the titanium target, use the graphite target as the cathode, use argon as the reaction gas, gradually increase the negative bias voltage during the deposition process, and deposit a gradient DLC layer on the second base layer;

[0051] (5) Using the graphite target as the cathode, applying a high / low negative bias voltage that changes periodically during the deposition process to deposit a DLC functional layer on the gradient DLC layer;

[0052] (6) The graphite target is turned off, and a chromium target or a multi-element alloy target is used as a cathode and nitrogen is used as a reaction gas to deposit a protective layer on the DLC functional layer, thereby obtaining the ablation-resistant, wear-resistant and friction-reducing coating piston ring.

[0053] In the present invention, the piston ring matrix also includes pretreatment before use; the pretreatment is ultrasonic cleaning to remove impurities such as grease and dirt on the surface of the piston ring matrix. The present invention does not limit the conditions of ultrasonic cleaning, and conventional methods in the art can be used.

[0054] In the present invention, the vacuum coating equipment in step (1) is a conventional equipment in the art, and has a vacuum arc ion plating deposition function and a magnetron sputtering deposition function, and the present invention does not limit this.

[0055] In the present invention, the heating temperature in step (1) is preferably 100-150°C, more preferably 130-150°C, and more preferably 150°C.

[0056] In the present invention, the vacuum degree of the vacuum pumping in step (1) is preferably 5×10 -3 Pa.

[0057] In the present invention, the parameters of the ion cleaning in step (1) are: the negative bias voltage is preferably -800 to -1200 V, more preferably -900 to -1100 V, and more preferably -1000 V; the ion cleaning time is preferably 90 to 120 min, more preferably 95 to 110 min, and more preferably 110 min.

[0058] In the present invention, the parameters of the first bottom layer deposition in step (2) are: the vacuum degree is preferably 1×10 -3 Pa; the cathode current is preferably 80-120A, further preferably 90-115A, more preferably 100A; the negative bias voltage is preferably -17-23V, further preferably -19-22V, more preferably -21V; the gas pressure is preferably 1-2Pa, further preferably 1-1.7Pa, more preferably 1Pa; the deposition time is preferably 55-75min, further preferably 60-72min, more preferably 65min.

[0059] In the present invention, the parameters for depositing the second bottom layer in step (3) are: the vacuum degree is preferably 1×10 -3 Pa; the power of magnetron sputtering is preferably 5-10kW, more preferably 6-9kW, more preferably 8kW; the negative bias voltage is preferably -100-200V, more preferably -150-200V, more preferably -200V; the gas pressure is preferably 0.2-2Pa, more preferably 0.6-1.5Pa, more preferably 1Pa; the deposition time is preferably 55-75min, more preferably 58-72min, more preferably 60min.

[0060] In the present invention, the parameters of the step (4) for depositing the gradient DLC layer are: the vacuum degree is preferably 1×10 -3 Pa; the cathode current is preferably 80-180A, further preferably 85-140A, and more preferably 130A; the negative bias voltage is preferably increased uniformly from -800V to -2000V during the deposition time; the deposition time is preferably 50-80min, further preferably 55-70min, and more preferably 60min.

[0061] In the present invention, the parameters for depositing the DLC functional layer in step (5) are: the vacuum degree is preferably 1×10 -3Pa; the cathode current is preferably 80-180A, further preferably 100-170A, and more preferably 145A; the period is preferably 2-3s, and more preferably 2s; the high negative bias in the high / low negative bias is preferably -1600-2500V, further preferably -1800-2200V, and more preferably -2100V; the low negative bias in the high / low negative bias is preferably -600-1000V, further preferably -650-900V, and more preferably -800V; the deposition time is preferably 5-30h, further preferably 10-20h, and more preferably 17h.

[0062] In the present invention, the parameters of the deposited protective layer in step (6) are: the nitrogen flow rate is preferably 35-45sccm, more preferably 37-42sccm, and more preferably 40sccm; the cathode current is preferably 100-120A, more preferably 100-110A, and more preferably 100A; the negative bias voltage is preferably -20-25V, more preferably -21-24V, and more preferably -22V; the deposition time is preferably 30-120min, more preferably 40-60min, and more preferably 45min.

[0063] The present invention also provides an engine, in which the erosion-resistant wear-resistant and friction-reducing coating piston ring or the erosion-resistant wear-resistant and friction-reducing coating piston ring prepared by the preparation method of the erosion-resistant wear-resistant and friction-reducing coating piston ring is adopted.

[0064] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Example 1

[0066] This embodiment provides an anti-ablation wear-resistant and friction-reducing coating piston ring, which includes a 20 μm wear-resistant and friction-reducing layer and a 2.5 μm CrN layer from bottom to top on the outer circumferential surface of the piston ring substrate;

[0067] The wear-resistant and friction-reducing layers are, from bottom to top, a chromium layer, a titanium layer, a gradient DLC layer, and a DLC functional layer.

[0068] The method for preparing the ablation-resistant wear-resistant and friction-reducing coating piston ring comprises the following steps:

[0069] (1) The piston ring substrate after ultrasonic cleaning and drying is placed in a vacuum coating device, and the cavity of the vacuum coating device is heated and vacuumized; when the temperature reaches 150°C and the vacuum degree reaches 5×10 -3Pa, 99.99% pure argon gas was introduced, the outer cylindrical surface of the piston ring substrate was used as the plated surface, a negative bias voltage of -1000 V was applied, and the outer cylindrical surface was ion cleaned for 110 minutes;

[0070] (2) When the vacuum degree is reduced to 1×10 -3 After 1000 Pa, a chromium layer was deposited on the outer cylindrical surface after ion cleaning, with a chromium target as the cathode, argon as the reaction gas, a cathode current of 100A, a gas pressure of 1Pa, and a negative bias of -20V. The deposition time was 65min.

[0071] (3) Turn off the chromium target and when the vacuum drops to 1×10 -3 After Pa, a titanium target was used as a magnetron sputtering target, argon was used as a reaction gas, the sputtering power was set to 8 kW, the gas pressure was 1 Pa, a negative bias voltage of -200 V was applied, and a titanium layer was deposited on the chromium layer for 60 min.

[0072] (4) Turn off the titanium target and when the vacuum drops to 1×10 -3 After Pa, the graphite target was used as the cathode, the cathode current was 130A, and the negative bias voltage was uniformly increased from -800V to -2000V within 60min, and the gradient DLC layer was deposited on the titanium layer for 60min.

[0073] (5) When the vacuum degree is reduced to 1×10 -3 After Pa, the graphite target was used as the cathode, the cathode current was 145A, and a high / low negative bias voltage was applied in a 2s cycle during the deposition process. The high negative bias voltage was -2100V and the low negative bias voltage was -800V. The DLC functional layer was deposited on the gradient DLC layer for 17h.

[0074] (6) The graphite target is turned off, and the chromium target is used as the cathode, nitrogen is used as the reaction gas, the nitrogen flow rate is 40 sccm, the cathode current is 100 A, the negative bias voltage is -22 V, and a CrN layer is deposited on the DLC functional layer for 45 min to obtain the ablation-resistant, wear-resistant and friction-reducing coating piston ring.

[0075] Example 2

[0076] This embodiment provides an anti-ablation wear-resistant and friction-reducing coating piston ring, which includes a 20 μm wear-resistant and friction-reducing layer and a 3 μm CrAlN layer on the outer circumferential surface of the piston ring substrate from bottom to top;

[0077] The wear-resistant and friction-reducing layers are, from bottom to top, a chromium layer, a titanium layer, a gradient DLC layer, and a DLC functional layer.

[0078] The preparation method of the anti-ablation wear-resistant and anti-friction coating piston ring is specifically described in Example 1, except that in step (6), the CrAl target material is used as the cathode, the nitrogen flow rate is 35 sccm, the cathode current is 100 A, the negative bias voltage is -25 V, and the deposition time is 58 min.

[0079] Example 3

[0080] This embodiment provides an anti-ablation wear-resistant and friction-reducing coating piston ring, which includes a 20 μm wear-resistant and friction-reducing layer and a 3 μm CrMoN layer on the outer circumferential surface of the piston ring substrate from bottom to top;

[0081] The wear-resistant and friction-reducing layers are, from bottom to top, a chromium layer, a titanium layer, a gradient DLC layer, and a DLC functional layer.

[0082] The preparation method of the anti-ablation wear-resistant and friction-reducing coating piston ring is specifically described in Example 1, except that in step (6), the CrMo target material is used as the cathode, the nitrogen flow rate is 45 sccm, the cathode current is 120A, the negative bias voltage is -20V, and the deposition time is 55min.

[0083] Comparative Example 1

[0084] The comparative example is a wear-resistant and friction-reducing coating piston ring, which includes a 23 μm wear-resistant and friction-reducing layer from bottom to top on the outer circumferential surface of the piston ring substrate. The preparation method of the wear-resistant and friction-reducing coating piston ring is specifically referred to Example 2, except that the deposition time in step (5) is 19.5 hours, and step (6) is not performed.

[0085] The piston rings prepared in Examples 1 to 3 and Comparative Example 1 were subjected to a heat resistance test. The specific method was as follows: the piston rings were placed in a muffle furnace, heated to temperature T and kept warm for 24 hours, then the piston rings were taken out, cooled to room temperature, and then the coating integrity and appearance before and after the test were observed. Figure 3 to Figure 6 The evaluation results of the morphology after the test are shown in Table 1.

[0086] Table 1 Evaluation of morphology results after heat resistance test

[0087]

[0088] From Table 1 and Figure 3 to Figure 6 It can be seen that the piston ring coating with a protective layer of the present invention can ensure the integrity of the coating after the heat resistance test at 300°C or even 400°C, without peeling and obvious color difference, indicating that the coating of the present invention has good anti-ablation performance, and the protective layer is continuously deposited in the same equipment after the DLC functional layer is deposited, so that the protective layer can be well combined with the DLC wear-resistant and friction-reducing coating. However, the coating of Comparative Example 1 has peeling at the edge after the heat resistance test at 400°C (such as Figure 3As shown in (d), it means that the anti-ablation performance is obviously deteriorated without the protective layer.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A piston ring with a wear-resistant and friction-reducing coating having an anti-ablation property, characterized in that: The outer circumferential surface of the piston ring substrate comprises a wear-resistant and friction-reducing layer and a protective layer from bottom to top; The wear-resistant and friction-reducing layers are, from bottom to top, a first primer layer, a second primer layer, a gradient DLC layer, and a DLC functional layer; The protective layer is a single nitride layer or a multi-nitride layer.

2. The ablation-resistant, wear-resistant, and friction-reducing coating piston ring according to claim 1, characterized in that: The thickness of the wear-resistant and friction-reducing layer is 10 to 23 μm; the thickness of the protective layer is 1 to 5 μm.

3. The ablation-resistant, wear-resistant and friction-reducing coating piston ring according to claim 2, characterized in that: The single nitride layer is a chromium nitride layer; the multi-component nitride layer is a Cr(Me)N layer, wherein Me is one or more of Al, Mo, W, B, Si, and Ti.

4. The ablation-resistant, wear-resistant and friction-reducing coating piston ring according to claim 1 or 3, characterized in that: The first primer layer is a chromium layer; the second primer layer is a titanium layer.

5. The method for preparing a piston ring with an ablation-resistant wear-resistant and friction-reducing coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) placing the piston ring substrate in a vacuum coating device, heating and evacuating the cavity of the vacuum coating device; then introducing argon gas, using the outer cylindrical surface of the piston ring substrate as the coating surface, and performing ion cleaning on the outer cylindrical surface; (2) using a chromium target as a cathode and argon as a reaction gas to deposit a first primer layer on the outer cylindrical surface after ion cleaning; (3) turning off the chromium target, using the titanium target as a magnetron sputtering target and argon as a reaction gas to deposit a second base layer on the first base layer; (4) Turn off the titanium target, use the graphite target as the cathode, use argon as the reaction gas, gradually increase the negative bias voltage during the deposition process, and deposit a gradient DLC layer on the second base layer; (5) Using the graphite target as the cathode, applying a high / low negative bias voltage that changes periodically during the deposition process to deposit a DLC functional layer on the gradient DLC layer; (6) The graphite target is turned off, and a chromium target or a multi-element alloy target is used as a cathode and nitrogen is used as a reaction gas to deposit a protective layer on the DLC functional layer, thereby obtaining the ablation-resistant, wear-resistant and friction-reducing coating piston ring.

6. The method for preparing a piston ring with an anti-ablation wear-resistant and anti-friction coating according to claim 5, characterized in that: The parameters for depositing the first bottom layer in step (2) are: vacuum degree is 1×10 -3 Pa; cathode current is 80~120A; negative bias voltage is -17~-23V; gas pressure is 1~2Pa; deposition time is 55~75min; The parameters for depositing the second bottom layer in step (3) are: vacuum degree is 1×10 -3 Pa; the power of magnetron sputtering is 5 to 10 kW; the negative bias voltage is -100 to -200 V; the gas pressure is 0.2 to 2 Pa; and the deposition time is 55 to 75 min.

7. The method for preparing a piston ring with an ablation-resistant wear-resistant and friction-reducing coating according to claim 6, characterized in that: The parameters for depositing the gradient DLC layer in step (4) are: vacuum degree is 1×10 -3 Pa; cathode current is 80~180A; negative bias voltage is uniformly increased from -800V to -2000V during deposition time; deposition time is 50~80min.

8. The method for preparing a piston ring with an ablation-resistant wear-resistant and friction-reducing coating according to claim 5 or 7, characterized in that: The parameters for depositing the DLC functional layer in step (5) are: vacuum degree is 1×10 -3 Pa; cathode current is 80-180A; high / low negative bias voltage is applied alternatingly in a period of 2-3s; the high negative bias voltage in the high / low negative bias voltage is -1600-2500V; the low negative bias voltage in the high / low negative bias voltage is -600-1000V; the deposition time is 5-30h.

9. The method for preparing a piston ring with an ablation-resistant wear-resistant and friction-reducing coating according to claim 8, characterized in that: The parameters for depositing the protective layer in step (6) are: nitrogen flow rate of 35 to 45 sccm; cathode current of 100 to 120 A; negative bias voltage of -20 to -25 V; and deposition time of 30 to 120 min.

10. An engine, characterized in that: The engine uses the erosion-resistant wear-resistant and friction-reducing coated piston ring described in any one of claims 1 to 4 or the erosion-resistant wear-resistant and friction-reducing coated piston ring prepared by the preparation method of the erosion-resistant wear-resistant and friction-reducing coated piston ring described in any one of claims 5 to 9.

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