Anti-wear lubricating coating and application thereof

Abstract

The invention discloses an anti-wear lubricating coating and application thereof, and relates to the technical field of anti-wear lubricating materials. The anti-wear lubricating coating is composed of a Cr coating and a chromium oxide and chromium phosphate lubricating film formed on the surface of the Cr coating. According to the anti-wear lubricating coating disclosed by the invention, a lubricating film is formed on the surface of the Cr coating by utilizing a friction chemical reaction between a Cr or Cr carbide doped phase and lubricating oil, so that the friction coefficient of the Cr coating under oil lubrication and boundary lubrication conditions can be further reduced, and the wear resistance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of anti-wear lubricating materials, and in particular to an anti-wear lubricating coating and application thereof. Background Art

[0002] High-speed compressors (compressors with speeds above 100Hz) can achieve the same output capacity as low-speed, large-displacement compressors under lower displacement design conditions, and have the characteristics of small size and low cost. They are currently widely used in the refrigeration and air-conditioning industry.

[0003] For the motor of a high-speed compressor, the speed of the high-speed motor is relatively high, and the centrifugal force of the rotor is relatively large. At this time, the crankshaft is subjected to the combined effect of magnetic pull and gas force during operation. Due to the different forces in different positions, the friction between the crankshaft and the main shaft is also different, and deformations of varying degrees will occur. Especially when the speed of the rotor is close to the critical speed, the rotor will experience severe bending vibrations, which may cause damage to the rotor in severe cases. Therefore, the motor shaft system structure and the corresponding bearing system need to adopt a special form. And because the speed is very high, traditional mechanical bearings are difficult to meet this requirement, so bearings that can meet high speed requirements are needed.

[0004] For high-efficiency compressors, the smaller the crankshaft diameter, the more beneficial it is to reducing mechanical friction losses and improving performance. On the one hand, reducing the diameter can increase the contact area of ​​the support surface of the eccentric part of the crankshaft, reduce the contact stress of the friction surface, and reduce the friction power consumption of the support surface. On the other hand, it can reduce the friction torque of the bearing and reduce the friction power consumption of the bearing.

[0005] The development of ultra-high energy-efficiency compressors has resulted in increasingly thicker motors and thinner crankshaft diameters; the development of ultra-high speed compressors has resulted in miniaturization of products using the high frequency of the compressors. However, both of these product development directions have encountered problems such as insufficient crankshaft stiffness, large deflection leading to bending deformation, and reduced reliability. Therefore, how to improve the crankshaft's anti-friction and wear resistance and the deterioration of the crankshaft's deflection is a major problem in this field. Summary of the invention

[0006] One of the purposes of the present invention is to develop an anti-wear lubricating coating that can be used on the crankshaft surface to reduce the friction coefficient and wear rate, thereby improving the anti-friction and anti-wear properties of the crankshaft; another purpose of the present invention is to solve the problem of deflection deterioration of the rotor shaft system of a high-speed compressor and the problem of local contact deterioration caused by a high-rigidity crankshaft (the contact area at the root of the long shaft is small and the oil film is easily broken).

[0007] The invention of the present invention is:

[0008] On the crankshaft surface, a Cr coating and a matching extreme pressure anti-wear agent are used to form an anti-wear lubricating coating to solve the problem of insufficient crankshaft friction performance. At the same time, a high-rigidity crankshaft is used to solve the problem of deflection deterioration of the rotor shaft system of high-speed and small-diameter compressors, thereby improving the reliability of the compressor.

[0009] The objectives of the present invention are achieved through the following technical solutions.

[0010] An anti-wear lubricating coating consists of a Cr coating and a chromium oxide and chromium phosphate lubricating film formed on the surface of the Cr coating.

[0011] Preferably, the lubricating film is formed by friction between an extreme pressure anti-wear agent and a lubricating oil base oil at 50-150°C on the surface of the Cr coating; the extreme pressure anti-wear agent is zinc dialkyl dithiophosphate (ZDDP). The active element P in ZDDP undergoes a tribochemical reaction with the element chromium (Cr) in the Cr coating to generate chromium oxide (CrO) with anti-wear and friction-reducing effects at the friction interface. x ) and chromium phosphate lubricating film prevents direct contact between the friction partners, thereby reducing the friction coefficient and lowering the wear rate.

[0012] Preferably, the mass content of the extreme pressure anti-wear agent accounts for 0.5-1.5% of the total mass of the extreme pressure anti-wear agent and the lubricating oil base oil.

[0013] In some other embodiments, the lubricating oil base oil is a pentaerythritol ester base oil. Preferably, the fatty acid used to prepare the pentaerythritol ester base oil is composed of isooctanoic acid and isononanoic acid, and the molar ratio of isooctanoic acid to isononanoic acid is 42:60-60:42. The lubricating oil base oil has good compatibility with the extreme pressure anti-wear agent and can be well adapted thereto. At low temperatures above -40°C, ZDDP is compatible with the pentaerythritol ester base oil within a content range of 0.5%-1.5%.

[0014] In some other embodiments, the Cr coating is a PVD coating containing Cr elements. PVD coating refers to a process method that uses physical methods to transfer atoms or molecules from a target to the surface of a substrate. Its function is to coat a material with excellent performance (high strength, good wear resistance, strong heat dissipation, and excellent corrosion resistance) on a substrate with lower performance, so that the substrate has better performance. PVD treatment has the advantages of low deposition temperature, almost no deformation of the workpiece, fine coating structure, strong resistance to crack propagation, smooth coating surface, many types of film formation, low requirements on the substrate, etc., and no secondary treatment is required after the coating is deposited, which is very suitable for use on friction moving parts.

[0015] In some other embodiments, the PVD coating is a CrN or TiAlCrN coating.

[0016] The present invention also provides a crankshaft, the surface of which is covered with the above-mentioned anti-wear lubricating coating. The anti-wear lubricating coating can significantly enhance the comprehensive performance of the base material and play a strong role in resisting friction and wear.

[0017] In some other embodiments, the crankshaft is made of 42CrMo, the Cr coating has a thickness of 5-6 μm, and a surface roughness of 0.3-0.5 μm. 42CrMo has a high elastic modulus and has high rigidity as a crankshaft, which can reduce the deflection of the compressor crankshaft and relatively reduce the shaft diameter, thereby improving the compressor performance.

[0018] Preferably, the Cr coating of the anti-wear lubricating coating is formed by coating the Cr-containing material on the crankshaft surface through multi-arc ion plating and magnetron sputtering technology to form a PVD coating; the PVD coating is preferably a CrN or TiAlCrN coating, and the friction chemical reaction between the Cr coating and the lubricating oil (the above-mentioned extreme pressure anti-wear agent and lubricating oil base oil) medium is used to generate a lubricating film, which can further reduce the friction coefficient of the lubricating film under oil lubrication and boundary lubrication conditions, thereby improving the wear resistance and service stability of the crankshaft surface.

[0019] The present invention also provides an air-conditioning compressor, which uses 42CrMo as a crankshaft, forms a Cr coating on the crankshaft surface by multi-arc ion plating and magnetron sputtering technology, mixes an extreme pressure anti-wear agent and a lubricating oil base oil to make a lubricating oil, and then places it in a compressor oil pool. When the compressor is running, the lubricating oil is brought to the crankshaft surface along the compressor oil circuit, and during the operation of the compressor, the lubricating oil forms a lubricating film of chromium oxide and chromium phosphate at the friction interface of the crankshaft, thereby reducing the friction coefficient of the crankshaft and the wear rate. It should be noted that the temperature during the operation of the air-conditioning compressor is 50-150°C.

[0020] The anti-wear lubricating coating of the present invention forms a lubricating film on the surface of the Cr coating by means of the tribochemical reaction between the Cr or Cr carbide doped phase and the lubricating oil, which can further reduce the friction coefficient of the Cr coating under oil lubrication and boundary lubrication conditions and improve the wear resistance.

[0021] The high-rigidity crankshaft with the anti-wear lubricating coating can solve the problems of deterioration of the rotor shaft system deflection and insufficient crankshaft friction performance of high-speed small-diameter compressors, thereby improving the reliability of the compressor. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0023] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0024] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0025] Example 1

[0026] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0027] Base material: 42CrMo;

[0028] PVD coating (Cr coating): CrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0029] Lubricating film: Lubricating oil formed by mixing 0.5% by mass of ZDDP and 99.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0030] Example 2

[0031] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0032] Base material: 42CrMo;

[0033] PVD coating (Cr coating): TiAlCrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0034] Lubricating film: Lubricating oil formed by mixing 0.5% by mass of ZDDP and 99.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0035] Example 3

[0036] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0037] Base material: 42CrMo;

[0038] PVD coating (Cr coating): CrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0039] Lubricating film: Lubricating oil formed by mixing 1.0% by mass of ZDDP and 99.0% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0040] Example 4

[0041] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0042] Base material: 42CrMo;

[0043] PVD coating (Cr coating): TiAlCrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0044] Lubricating film: Lubricating oil formed by mixing 1.0% by mass of ZDDP and 99.0% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0045] Example 5

[0046] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0047] Base material: 42CrMo;

[0048] PVD coating (Cr coating): CrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0049] Lubricating film: Lubricating oil formed by mixing 1.5% by mass of ZDDP and 98.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0050] Example 6

[0051] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0052] Base material: 42CrMo;

[0053] PVD coating (Cr coating): TiAlCrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0054] Lubricating film: Lubricating oil formed by mixing 1.5% by mass of ZDDP and 98.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 100±2°C.

[0055] Example 7

[0056] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0057] Base material: 42CrMo;

[0058] PVD coating (Cr coating): CrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0059] Lubricating film: Lubricating oil formed by mixing 0.5% by mass of ZDDP and 99.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 50±2°C.

[0060] Example 8

[0061] The crankshaft of this embodiment is covered with an anti-wear lubricating coating on its surface. The anti-wear lubricating coating is composed of a PVD coating (Cr coating) and a lubricating film formed on the surface of the PVD coating (Cr coating), as described below.

[0062] Base material: 42CrMo;

[0063] PVD coating (Cr coating): TiAlCrN (thickness 5-6μm, surface roughness 0.3-0.5μm);

[0064] Lubricating film: Lubricating oil formed by mixing 0.5% by mass of ZDDP and 99.5% of pentaerythritol ester base oil is generated by friction on the surface of the PVD coating at 150±2°C.

[0065] In other descriptions, the crankshafts in Examples 1-8 can be used in air-conditioning compressors. Specifically, the lubricating oil in Examples 1-8 is placed in a compressor oil pool, and the lubricating oil is brought to the crankshaft surface along the compressor oil path when the compressor is running, and the lubricating oil forms a lubricating film of chromium oxide and chromium phosphate on the crankshaft friction interface during the operation of the compressor.

[0066] In order to study the performance of the crankshafts of Examples 1-8, the following friction tests were performed according to the base material and base surface PVD coating of the crankshafts of Examples 1-8 shown in Table 1:

[0067] The PVD coatings of the substrates of the above-mentioned embodiments 1-8 were subjected to friction tests by a UMT-5 friction testing machine. The lubricating oil components (the lubricating oil base oil is a polyol ester viscosity grade 68 lubricating oil base oil) and the friction test temperature (i.e., the lubricating oil temperature during the friction process) used in the friction tests of embodiments 1-8 are shown in Table 1; the experiment adopts a reciprocating motion mode, the single stroke is set to 5 mm, the vertical load is 8 N, the frequency is set to 2 Hz, the time is 10 min, the diameter of the dual steel ball is Ф4 mm, the steel ball material is GCr15, the grade is G10 and 25Ep (super light), and the hardness is HRC62-65.

[0068] After the friction test, the crankshaft surface was cleaned to obtain the crankshafts of Examples 1-8 for testing.

[0069] Table 1

[0070]

[0071] The following tests were performed on the crankshafts of Examples 1-8.

[0072] Vickers hardness: GB / T4342.1 "Vickers hardness test for metallic materials - Part 1: Test method".

[0073] Elastic modulus: GB / T3354-2018 "Determination of elastic modulus of metallic materials at room temperature".

[0074] Wear rate and friction coefficient: Detect the friction coefficient (the experiment was repeated three times to take the average value); use white light interferometer to test the wear volume of the crankshaft surface. The calculation formula of the wear rate is as follows:

[0075] WR=V / F·S;WR: wear rate (mm 3 / N·m); V: wear volume (mm 3 );F:load(N);S:range(m).

[0076] Surface element analysis: X-ray photoelectron spectroscopy (XPS) was used to perform elemental analysis on the crankshaft surface after the friction test using the surface-sensitive XPS technique (before XPS analysis, the crankshaft was cleaned with n-heptane to remove residual oil and contaminants); CasaXPS software was used to curve fit the XPS peaks obtained by long scanning, and the peak area sensitivity factor was used to quantitatively analyze the peaks.

[0077] The test results of Vickers hardness, elastic modulus, friction coefficient and wear rate of the crankshafts of Examples 1-8 are shown in Table 2.

[0078] Table 2 Test results of Vickers hardness, elastic modulus, friction coefficient and wear rate of crankshafts of Examples 1-8

[0079] Example Elastic modulus Surface Vickers hardness Friction coefficient Wear rate Example 1 205GPa HV2230 0.11 0.42 Example 2 207GPa HV4513 0.133 0.38 Example 3 205GPa HV2230 0.076 0.06 Example 4 207GPa HV4513 0.081 0.08 Example 5 205GPa HV2230 0.123 0.13 Example 6 207GPa HV4513 0.145 0.14 Example 7 205GPa HV2230 0.088 0.26 Example 8 205GPa HV2230 0.08 0.36

[0080] The surface element analysis results of the crankshafts of Examples 1-8 are shown in Table 3 below.

[0081] Table 3 Surface element analysis results of crankshafts of Examples 1-8

[0082]

[0083] During the research of the present invention, the crankshaft performance of comparative examples 1-9 was also verified. The substrate material and substrate surface PVD coating degree of the crankshafts of comparative examples 1-9 are as follows.

[0084] Comparative Example 1

[0085] Base material: QT700;

[0086] PVD coating: No.

[0087] Comparative Example 2

[0088] Base material: 42CrMo;

[0089] PVD coating: No.

[0090] Comparative Example 3

[0091] Base material: 42CrMo;

[0092] PVD coating: CrN (thickness 5-6μm, surface roughness 0.3-0.5μm).

[0093] Comparative Example 4

[0094] Base material: 42CrMo;

[0095] PVD coating: TiAlCrN (thickness 5-6 μm, surface roughness 0.3-0.5 μm).

[0096] Comparative Example 5

[0097] Base material: 42CrMo;

[0098] PVD coating: No.

[0099] Comparative Example 6

[0100] Base material: 42CrMo;

[0101] PVD coating: CrN (thickness 5-6μm, surface roughness 0.3-0.5μm).

[0102] Comparative Example 7

[0103] Base material: 42CrMo;

[0104] PVD coating: TiN (thickness 5-6 μm, surface roughness 0.3-0.5 μm).

[0105] Comparative Example 8

[0106] Base material: 42CrMo;

[0107] PVD coating: CrN (thickness 5-6μm, surface roughness 0.3-0.5μm).

[0108] Comparative Example 9

[0109] Base material: 42CrMo;

[0110] PVD coating: CrN (thickness 5-6μm, surface roughness 0.3-0.5μm).

[0111] The crankshafts of the above-mentioned comparative examples 1-8 were subjected to friction tests respectively by using a UMT-5 friction tester. The lubricating oil components (the lubricating oil base oil is a polyol ester viscosity grade 68 lubricating oil base oil) and the friction test temperature (i.e., the lubricating oil temperature during the friction process) used in the friction tests of comparative examples 1-8 are shown in Table 4. The conditions for conducting the friction test are the same as those in Example 1.

[0112] After the friction test, the crankshaft surface was cleaned to obtain the crankshafts to be tested of Comparative Examples 1-8.

[0113] The crankshaft of Comparative Example 9 was immersed in the lubricating oil shown in Table 4 at 100° C. for 10 minutes. After the immersion, the surface of the crankshaft was cleaned to obtain the crankshaft to be tested of Comparative Example 9.

[0114] Table 4

[0115]

[0116] The Vickers hardness, elastic modulus, friction coefficient and wear rate of the crankshafts to be tested in Comparative Examples 1-8 were tested, and the test results are shown in Table 5.

[0117] Table 5 Test results of the crankshafts to be tested in comparative examples 1-8

[0118]

[0119]

[0120] Surface element analysis was performed on the crankshafts to be tested in comparative examples 3, 4, 6-9, and the results are shown in Table 6 below.

[0121] Table 6 Surface element analysis results of the crankshafts to be tested in comparative examples 3, 4, 6-9

[0122]

[0123] From the comparison of the test results in Table 2 and Table 5, we can see that:

[0124] The friction coefficient and wear rate of the crankshafts of Examples 1-9 of the present invention are lower than those of the crankshafts of Comparative Examples 1-8.

[0125] The test results of Examples 1-6 reflect the crankshaft friction performance at different ZDDP contents in the lubricating oil, wherein the crankshaft friction performance is optimal when the ZDDP content in the lubricating oil in Examples 3 and 4 is 1.0%.

[0126] Examples 7 and 8 verified the crankshaft friction performance when the friction test temperature was controlled at 50±2°C and 150±2°C, respectively. By comparing the test results of Example 3, it can be seen that the crankshaft friction performance is optimal when the friction test temperature is 100±2°C.

[0127] Further analysis of the test results of Comparative Examples 1-9 shows that, under the condition of no coating and no additives, the crankshaft of Comparative Example 2 using 42CrMo has a higher friction coefficient and a similar wear rate than the QT700 crankshaft used in Comparative Example 1; after adding PVD coating to the crankshafts of Comparative Examples 3 and 4, the friction coefficient and wear rate are greatly reduced; further, after adding ZDDP extreme pressure anti-wear agent to 1-9 of the present invention, the friction coefficient and wear rate of the crankshaft are greatly reduced again, indicating that ZDDP has an excellent effect on improving the friction performance of the crankshaft. At the same time, if the PVD coating is cancelled (Comparative Example 5), the friction coefficient and wear rate of the crankshaft are increased, indicating that the PVD coating and ZDDP have obvious synergistic effects and are indispensable.

[0128] The crankshaft material QT700 of Comparative Example 1 is a commonly used material for existing compressor crankshafts, and has a high wear rate and friction coefficient. The material of Comparative Example 2 is the 42CrMo material used for the crankshaft of the present invention, and has a high wear rate and friction coefficient, but a higher elastic modulus than QT700. Therefore, the 42CrMo material crankshaft has better stiffness and deflection performance, but the wear rate and friction coefficient are also high.

[0129] The test results of comparative examples 3 / 4 are the crankshaft performance of 42CrMo+CrN / TiAlCrN in the absence of lubricating oil anti-wear agent, and its surface Vickers hardness and elastic modulus are higher than those of the crankshaft of comparative example 1; the wear rate and friction coefficient of the crankshaft are also reduced compared with those of comparative examples 1 and 2, but higher than those of the embodiment; the test results of comparative example 5 are the crankshaft performance of 42CrMo+1.0%ZDDP without coating, and its wear rate and friction coefficient are also reduced, but higher than those of the embodiment, indicating that the coating Cr and the ZDDP extreme pressure anti-wear agent in the present invention have obvious synergistic effects and are indispensable.

[0130] The test results of Comparative Example 6 are the crankshaft performance when the friction test temperature is controlled at 30±2°C. Its wear rate and friction coefficient are also reduced, but higher than those of the embodiment.

[0131] The test results of comparative example 7 are the performance of the crankshaft in which the PVD coating is replaced with a Cr-free TiN coating. Its wear rate and friction coefficient are slightly lower than those of comparative example 5, but not as good as the friction performance of the crankshaft of the embodiment.

[0132] The test results of Comparative Example 8 are the crankshaft performance when the anti-wear agent is changed to the anti-wear agent T306 (tricresyl phosphate) which also contains phosphorus. Its friction coefficient is equivalent to that of the embodiment, but the wear rate is higher.

[0133] From the comparison of the test results in Table 3 and Table 6, we can see that:

[0134] Comparison of the test results of Comparative Example 3 / Comparative Example 4 with Example 3 / Example 4 shows that after adding 1% ZDDP to the lubricating oil, the oxygen and phosphorus elements on the friction surface of the crankshaft obtained in Example 3 / Example 4 increased, indicating that a large amount of chromium oxide (CrOx) and chromium phosphate were generated, thereby enhancing the friction performance.

[0135] Compared with the test results of Comparative Example 6, the phosphorus element on the crankshaft friction surface increased to a certain extent, but the oxygen element did not increase, indicating that only a small amount of phosphate and chromium oxide were generated at this temperature.

[0136] Compared with the test results of Comparative Example 7 and Comparative Example 3, there is only a slight amount of phosphorus on the friction surface of the crankshaft, indicating that there is no obvious chemical reaction between ZDDP and the TiN coating.

[0137] Compared with the test results of Comparative Example 8, the phosphorus element on the crankshaft friction surface increased to a certain extent, but the oxygen element did not increase, indicating that only a small amount of phosphate and chromium oxide were generated at this temperature.

[0138] Comparison of the test results of Example 9 with those of Example 3 shows that the oxygen element on the friction surface of the crankshaft in Example 9 did not increase, and there was only a very low phosphorus element, indicating that under the condition of no friction, there was no obvious chemical reaction between the ZDDP and the CrN coating.

[0139] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An anti-wear lubricating coating, characterized in that: It consists of a Cr coating and a chromium oxide and chromium phosphate lubricating film formed on the surface of the Cr coating.

2. The anti-wear lubricating coating according to claim 1, characterized in that: The lubricating film is generated by friction between an extreme pressure anti-wear agent and a lubricating oil base oil on the surface of the Cr coating at 50-150° C.; the extreme pressure anti-wear agent is zinc dialkyl dithiophosphate.

3. The anti-wear lubricating coating according to claim 2, characterized in that: The mass content of the extreme pressure anti-wear agent accounts for 0.5-1.5% of the total mass of the extreme pressure anti-wear agent and the lubricating oil base oil.

4. The anti-wear lubricating coating according to claim 1, characterized in that: The Cr coating is a PVD coating containing Cr element.

5. The anti-wear lubricating coating according to claim 4, characterized in that: The PVD coating is a CrN or TiAlCrN coating.

6. The anti-wear lubricating coating according to claim 2, characterized in that: The lubricating oil base oil is pentaerythritol ester base oil.

7. The anti-wear lubricating coating according to claim 6, characterized in that: The fatty acid used to prepare the pentaerythritol ester base oil consists of isooctanoic acid and isononanoic acid, and the molar ratio of isooctanoic acid to isononanoic acid is 42:60-60:

42.

8. A crankshaft, characterized in that: The surface is covered with an anti-wear lubricating coating as described in any one of claims 1 to 7.

9. The crankshaft according to claim 9, characterized in that: The crankshaft is made of 42CrMo, the Cr coating has a thickness of 5-6 μm, and a surface roughness of 0.3-0.5 μm.

10. An air-conditioning compressor, characterized in that: A crankshaft as claimed in claim 8 or 9 is used.

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