Titanium alloy surface wide-temperature-range self-lubricating coating and preparation method thereof

Abstract

The invention provides a titanium alloy surface wide-temperature-range self-lubricating coating and a preparation method thereof.The preparation method comprises the steps that a micro-arc oxidation coating is prepared on the titanium alloy surface; an emulsion is sprayed on the surface of the micro-arc oxidation coating and cured, the self-lubricating coating is obtained, the emulsion is a mixed solution of polyvinyl alcohol, molybdenum disulfide particles and deionized water, the mass percentage content of the polyvinyl alcohol is 1-3%, and the concentration of the molybdenum disulfide particles is 3-9 g / L. The titanium alloy surface wide-temperature-range self-lubricating coating prepared by the preparation method provided by the invention shows excellent high-temperature-resistant self-lubricating performance.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and specifically provides a wide-temperature-range self-lubricating coating on a titanium alloy surface and a preparation method thereof. Background Art

[0002] Titanium and its alloys have excellent properties such as low density, high specific strength, corrosion resistance, and good biocompatibility. They are widely used in aerospace, automotive, electronics, chemical, and medical fields. However, the wear resistance of titanium and its alloys is relatively poor, which limits their application to a certain extent. Therefore, surface modification technology is usually used to improve the wear resistance of titanium and titanium alloys. Currently, the main surface modification methods for improving the wear resistance of titanium and titanium alloys include mechanical methods, physical methods, and chemical methods. Among them, mechanical methods mainly use methods such as grinding, polishing and sandblasting to obtain an acceptable surface with a specific morphology or a certain roughness. Since mechanical methods have poor ability to improve surface properties, they are always used as an auxiliary method to obtain a better and clearer surface; physical methods mainly include thermal spraying, plasma spraying and laser surface modification technologies. Whether thermal spraying, plasma spraying or laser surface modification technology, they all improve the surface properties of the metal by combining certain specific materials with the metal surface to form a surface coating with specific properties; chemical methods mainly include chemical treatment technology and electrochemical treatment technology. They use the chemical reaction of certain elements with the substrate to generate oxides or compounds with certain high performance on the substrate surface, thereby greatly improving the surface properties of the metal. Micro-arc oxidation technology is a more advanced chemical surface modification technology. It is a technology developed on the basis of anodic oxidation. Its working principle relies on the matching and adjustment of electrolyte and electrical parameters. Under the instantaneous high temperature and high pressure generated by arc discharge, a modified ceramic coating composed mainly of matrix metal oxide and supplemented by electrolyte components grows on the surface of metals such as aluminum, magnesium, titanium and their alloys. This coating can be thick, reaching hundreds of microns, and its corrosion and wear resistance often surpasses traditional anodic oxidation coatings. Spray coating technology typically involves applying a custom-made spray emulsion manually or mechanically to create a coating with specific functionalities. However, spray coating often suffers from drawbacks such as poor adhesion to the substrate surface.

[0003] Therefore, how to combine micro-arc oxidation technology with spraying technology to prepare a functional coating with self-lubricating effect is of great significance in the field of material friction and wear. Summary of the Invention

[0004] In view of this, the present invention provides a wide temperature range self-lubricating coating on the surface of titanium alloy and a preparation method thereof to solve the problems of poor self-lubricating effect, poor wear resistance, and high friction coefficient of titanium alloy.

[0005] In one aspect, the present invention provides a method for preparing a wide-temperature-range self-lubricating coating on a titanium alloy surface, comprising:

[0006] Step 1: Prepare a base layer: prepare a micro-arc oxidation coating on the surface of the titanium alloy;

[0007] Step 2, preparing a self-lubricating coating: spraying an emulsion on the surface of the micro-arc oxidation coating and curing it to obtain a self-lubricating coating, wherein the emulsion is a mixture of polyvinyl alcohol, molybdenum disulfide particles and deionized water, the mass percentage of the polyvinyl alcohol is 1-3%, and the concentration of the molybdenum disulfide particles is 3-9 g / L.

[0008] Preferably, the specific steps of step 1 are as follows:

[0009] Step 1.1: Grind the surface of the titanium alloy to remove rust and make the surface of the titanium alloy smooth;

[0010] Step 1.2: After cleaning and drying the polished titanium alloy, the alloy is placed in an electrolyte for micro-arc oxidation treatment to obtain the micro-arc oxidation coating, wherein the micro-arc oxidation treatment adopts a bidirectional pulsed AC voltage with a forward voltage of 300-380V, a negative voltage of 60-140V, a pulse frequency of 100-500Hz, a duty cycle of 10-30%, and an oxidation time of 10-50min.

[0011] Further preferably, in step 1.2, the electrolyte composition of micro-arc oxidation is as follows: Na2SiO3·9H2O: 10-30 g / L; (NaPO3)6: 5-15 g / L; Na2MoO4: 2-6 g / L; KOH: 2-6 g / L.

[0012] More preferably, the thickness of the micro-arc oxidation coating is 23.4-33.8 μm.

[0013] Further preferably, before spraying the emulsion, the method further includes a step of cleaning the surface of the micro-arc oxidation coating.

[0014] More preferably, in step 2, the emulsion is sprayed 1-5 times, and curing is performed after each spraying.

[0015] More preferably, in step 2, the curing method is air-drying under natural conditions.

[0016] The present invention also provides a wide-temperature-range self-lubricating coating on the surface of a titanium alloy, which is prepared by the above-mentioned method for preparing the wide-temperature-range self-lubricating coating on the surface of a titanium alloy.

[0017] The present invention provides a method for preparing a wide-temperature-range self-lubricating coating on a titanium alloy surface. By preparing a layer of micro-arc oxidation coating on the titanium alloy surface, a space for attachment of molybdenum disulfide particles can be provided, which is beneficial to improving the bonding strength between the molybdenum disulfide particles and the substrate, making it difficult for the molybdenum disulfide particles to fall off, thereby ensuring the self-lubricating effect of the titanium alloy surface. The self-lubricating coating provided by the present invention can still maintain an excellent self-lubricating effect when rubbed at 400°C, greatly improving the application range of the titanium alloy. Taking into account the construction problems on the surfaces of certain complex-shaped parts, the present invention adopts spraying technology to prepare the self-lubricating coating, which can be conveniently operated in various environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is a graph showing the friction coefficient of the samples prepared in Examples 1-3 and Comparative Examples 1-4 at room temperature;

[0019] Figure 2 1 is a graph showing the friction coefficient of the samples prepared in Examples 1-3 and Comparative Examples 1-4 at a high temperature of 300°C;

[0020] Figure 3 1 is a graph showing the friction coefficient of the samples prepared in Examples 1-3 and Comparative Examples 1-4 at a high temperature of 400°C;

[0021] Figure 4 3 are macromorphological photographs of the self-lubricating coatings of Examples 1-3 at different stages. In the figure, (a1), (b1) and (c1) are macromorphological photographs of the base layer in Example 1, Example 2 and Example 3, respectively; (a2), (b2) and (c2) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3, respectively; (a3), (b3) and (c3) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after room temperature friction test, respectively; (a4), (b4) and (c4) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after 300°C friction test, respectively; (a5), (b5) and (c5) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after 400°C friction test, respectively;

[0022] Figure 5These are macromorphological photographs of the final samples of Comparative Examples 1-4 at different stages. In the figures, (a1), (b1), (c1) and (d1) are respectively macromorphological photographs of the surfaces of the samples of Comparative Examples 1-4, (a2), (b2), (c2) and (d2) are respectively macromorphological photographs of the surfaces of the samples of Comparative Examples 1-4 after room temperature friction tests, (a3), (b3), (c3) and (d3) are respectively macromorphological photographs of the surfaces of the samples of Comparative Examples 1-4 after 300°C friction tests, (a4), (b4), (c4) and (d4) are respectively macromorphological photographs of the surfaces of the samples of Comparative Examples 1-4 after 400°C friction tests. DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to specific embodiments.

[0024] The present invention provides a method for preparing a wide-temperature-range self-lubricating coating on a titanium alloy surface, comprising the following steps:

[0025] Step 1: Prepare a base layer: Prepare a micro-arc oxidation coating on the surface of the titanium alloy. The specific steps are as follows:

[0026] Step 1.1: Grind the surface of the titanium alloy to remove rust and make the surface smooth. Grind with 180#, 320#, 600#, 800#, and 1000# sandpaper in sequence.

[0027] Grinding can remove surface defects of titanium alloy and thoroughly clean its surface, which is beneficial to improving the flatness and molding quality of the subsequent base layer;

[0028] Step 1.2: After cleaning and drying the polished titanium alloy, the polished titanium alloy is placed in an electrolyte for micro-arc oxidation treatment to obtain the micro-arc oxidation coating, wherein the micro-arc oxidation treatment uses a bidirectional pulsed AC voltage with a forward voltage of 300-380V, a negative voltage of 60-140V, a pulse frequency of 100-500Hz, a duty cycle of 10-30%, and an oxidation time of 10-50min. The titanium alloy can be cleaned by ultrasonic cleaning with an anhydrous ethanol solution;

[0029] The micro-arc oxidation coating is beneficial to the protection of the titanium alloy surface and can also effectively provide attachment space for molybdenum disulfide particles;

[0030] The micro-arc oxidation electrolyte composition is as follows: Na2SiO3·9H2O: 10-30 g / L; (NaPO3)6: 5-15 g / L; Na2MoO4: 2-6 g / L; KOH: 2-6 g / L;

[0031] Preferably, the thickness of the micro-arc oxidation coating is 23.4-33.8 μm;

[0032] Step 2, preparing a self-lubricating coating: spraying an emulsion on the surface of the micro-arc oxidation coating and curing it to obtain a self-lubricating coating, wherein the emulsion is a mixture of polyvinyl alcohol, molybdenum disulfide particles and deionized water, the mass percentage of the polyvinyl alcohol is 1-3%, and the concentration of the molybdenum disulfide particles is 3-9 g / L;

[0033] Preferably, before spraying the emulsion, the surface of the micro-arc oxidation coating is cleaned, wherein the cleaning includes deionized water cleaning, anhydrous ethanol cleaning, etc. Preferably, the titanium alloy primer coating is cleaned by ultrasonic vibration using a cleaning solvent. Ultrasonic vibration cleaning has a better cleaning effect than other cleaning methods. It mainly uses a cleaning solvent and water as a medium and relies on the oscillation generated by ultrasonic waves in the liquid to remove dirt to achieve the purpose of cleaning. It is conducive to achieving a thorough cleaning of the surface of the titanium alloy micro-arc oxidation coating, thereby improving the film-forming quality of the subsequent self-lubricating coating;

[0034] The emulsion is sprayed for 1-5 times, and solidified after each spraying. Preferably, each spraying takes 2 seconds.

[0035] Among them, the curing method is to air-dry under natural conditions for 4-8 hours. Among them, air-drying under natural conditions is conducive to the gradual evaporation of water in the emulsion, and will not cause cracks on the surface of the self-lubricating coating due to the dispersant, thereby ensuring the flatness of the coating. In addition, it is also conducive to achieving a close combination of the self-lubricating coating and the micro-arc oxidation coating to form an integrated coating with self-lubricating properties.

[0036] The method for preparing a wide-temperature-range self-lubricating coating on a titanium alloy surface prepares a layer of micro-arc oxidation coating on the titanium alloy surface, which can provide adhesion space for molybdenum disulfide particles, thereby improving the bonding strength between the molybdenum disulfide particles and the substrate, making it difficult for the molybdenum disulfide particles to fall off, and thus ensuring the self-lubricating effect of the titanium alloy surface. The effect of the self-lubricating coating is mainly to reduce the wear phenomenon occurring during the friction process. Considering the construction problems on the surfaces of some complex-shaped parts, the present invention adopts spraying technology to prepare the self-lubricating coating, which can be conveniently operated in various environments.

[0037] The present invention also provides a wide-temperature-range self-lubricating coating on the surface of a titanium alloy, which is prepared by the above-mentioned method for preparing the wide-temperature-range self-lubricating coating on the surface of a titanium alloy.

[0038] Example 1

[0039] A method for preparing a wide-temperature range self-lubricating coating on a titanium alloy surface, comprising the following steps:

[0040] (1) Preparation of base layer:

[0041] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0042] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0043] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0044] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0045] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate nonahydrate Na2SiO3·9H2O (10 g / L), sodium hexametaphosphate (NaPO3)6 (5 g / L), sodium molybdate Na2MoO4 (6 g / L), and potassium hydroxide KOH (6 g / L) as electrolyte, place in electrolytic cell and set aside;

[0046] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 300V positive voltage, 100V negative voltage, 100Hz frequency, 10% duty cycle, and 50min oxidation time. After checking that everything is correct, start oxidation;

[0047] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0048] 8) The thickness of the generated base layer (micro-arc oxidation coating) is 24.8 μm, the weight gain is 0.0351 g, and the unit weight gain is 10.97×10 3 g·m -3 ;

[0049] (2) Preparation of self-lubricating coating:

[0050] 1) Spraying: The substrate after the primer layer is placed on a laboratory bench for spraying, with each spraying lasting 2 seconds. The spraying emulsion is a mixture of polyvinyl alcohol, molybdenum disulfide particles, and deionized water, wherein the mass percentage of the polyvinyl alcohol is 1% and the concentration of the molybdenum disulfide particles is 6g / L.

[0051] 2) Drying: Place the sprayed substrate in a fume hood and allow it to dry naturally;

[0052] 3) Repeat 1) and 2) 4 times (5 cycles in total);

[0053] 4) Weighing: Weigh the sample using an analytical balance and set aside;

[0054] 5) The weight gain of the self-lubricating coating is 0.0191 g, and the unit weight gain is 11.94 g·m -2 ;

[0055] (3) Friction and wear test:

[0056] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0057] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0058] The experimental results show that after applying the self-lubricating coating, the TC4 alloy sample exhibits excellent tribological properties: at room temperature, the friction coefficient of the coating is 0.09 and the wear loss is 0.0022g; at 300°C, the friction coefficient of the coating is 0.09 and the wear loss is 0.0169g; at 400°C, the friction coefficient of the coating is 0.07 and the wear loss is 0.0122g;

[0059] Example 2

[0060] A method for preparing a titanium alloy wide temperature range self-lubricating coating:

[0061] (1) Preparation of base layer:

[0062] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0063] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0064] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0065] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0066] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate nonahydrate Na2SiO3·9H2O (20 g / L), sodium hexametaphosphate (NaPO3)6 (10 g / L), sodium molybdate Na2MoO4 (4 g / L), and potassium hydroxide KOH (4 g / L) as electrolyte, place in electrolytic cell and set aside;

[0067] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 340V positive voltage, 140V negative voltage, 500Hz frequency, 20% duty cycle, and 30min oxidation time. After checking that everything is correct, start oxidation;

[0068] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0069] 8) The thickness of the generated base layer is 33.8 μm, the weight gain is 0.0603 g, and the unit weight gain is 18.84×10 3 g·m -3 ;

[0070] (2) Preparation of self-lubricating coating:

[0071] 1) Spraying: The substrate after the primer layer was placed on a laboratory bench and sprayed using a homemade sprayer for 2 seconds each time. The spray emulsion was a mixture of polyvinyl alcohol, molybdenum disulfide particles, and deionized water, wherein the mass percentage of the polyvinyl alcohol was 2% and the concentration of the molybdenum disulfide particles was 3g / L.

[0072] 2) Drying: Place the sprayed substrate in a fume hood and allow it to dry naturally;

[0073] 3) Repeat 1) and 2) twice (a total of 3 cycles);

[0074] 4) Weighing: Weigh the sample using an analytical balance and set aside;

[0075] 5) The weight gain of the generated self-lubricating coating is 0.0251 g, and the unit weight gain is 15.69 g·m -2 ;

[0076] (3) Friction and wear test:

[0077] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0078] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0079] The experimental results show that after applying the self-lubricating coating, the TC4 alloy sample exhibits excellent tribological properties: at room temperature, the friction coefficient of the coating is 0.07 and the wear loss is 0.0027g; at 300°C, the friction coefficient of the coating is 0.08 and the wear loss is 0.0158g; at 400°C, the friction coefficient of the coating is 0.15 and the wear loss is 0.0100g;

[0080] Example 3

[0081] A method for preparing a titanium alloy wide temperature range self-lubricating coating:

[0082] (1) Preparation of base layer:

[0083] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0084] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0085] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0086] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0087] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate Na2SiO3·9H2O (30 g / L), sodium hexametaphosphate (NaPO3)6 (15 g / L), sodium molybdate Na2MoO4 (2 g / L), and potassium hydroxide KOH (2 g / L) as electrolyte, place in electrolytic cell and set aside;

[0088] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 380V positive voltage, 60V negative voltage, 300Hz frequency, 30% duty cycle, and 10min oxidation time. After checking that everything is correct, start oxidation;

[0089] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0090] 8) The thickness of the generated base layer is 33.6 μm, the weight gain is 0.0566 g, and the unit weight gain is 17.69×10 3 g·m -3 ;

[0091] (2) Preparation of self-lubricating coating:

[0092] 1) Spraying: The substrate after the primer layer was placed on a laboratory bench and sprayed using a homemade sprayer for 2 seconds each time. The spray emulsion was a mixture of polyvinyl alcohol, molybdenum disulfide particles, and deionized water, wherein the mass percentage of the polyvinyl alcohol was 3% and the concentration of the molybdenum disulfide particles was 9 g / L.

[0093] 2) Drying: Place the sprayed substrate in a fume hood and allow it to dry naturally;

[0094] 3) Weighing: Weigh the sample using an analytical balance and set aside;

[0095] 4) The weight gain of the generated self-lubricating coating is 0.0241 g, and the unit weight gain is 15.06 g·m -2 ;

[0096] (3) Friction and wear test:

[0097] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0098] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0099] The experimental results show that after applying the self-lubricating coating, the TC4 alloy sample exhibits excellent tribological properties: at room temperature, the friction coefficient of the coating is 0.06 and the wear amount is 0.0005g; at 300°C, the friction coefficient of the coating is 0.07 and the wear amount is 0.0106g; at 400°C, the friction coefficient of the coating is 0.19 and the wear amount is 0.0145g; Comparative Example 1

[0100] A method for preparing a micro-arc oxidation coating on a titanium alloy surface:

[0101] (1) Preparation of base layer:

[0102] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0103] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0104] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0105] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0106] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate nonahydrate Na2SiO3·9H2O (10 g / L), sodium hexametaphosphate (NaPO3)6 (5 g / L), sodium molybdate Na2MoO4 (6 g / L), and potassium hydroxide KOH (6 g / L) as electrolyte, place in electrolytic cell and set aside;

[0107] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 300V positive voltage, 100V negative voltage, 100Hz frequency, 10% duty cycle, and 50min oxidation time. After checking that everything is correct, start oxidation;

[0108] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0109] 8) The weight gain of the generated base layer is 0.0362 g, and the unit weight gain is 11.31×10 3 g·m -3 ;

[0110] (2) Friction and wear test:

[0111] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0112] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0113] The experimental results show that the tribological properties of the TC4 alloy sample with only micro-arc oxidation coating as the base layer are as follows: at room temperature, the friction coefficient of the coating is about 0.30 and the wear amount is 0.0224g; at 300℃, the friction coefficient of the coating is about 0.35 and the wear amount is 0.0127g; at 400℃, the friction coefficient of the coating is about 0.27 and the wear amount is 0.0101g;

[0114] Comparative Example 2

[0115] A method for preparing a micro-arc oxidation coating on a titanium alloy surface:

[0116] (1) Preparation of the base layer, the process flow is as follows:

[0117] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0118] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0119] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0120] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0121] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate nonahydrate Na2SiO3·9H2O (20 g / L), sodium hexametaphosphate (NaPO3)6 (10 g / L), sodium molybdate Na2MoO4 (4 g / L), and potassium hydroxide KOH (4 g / L) as electrolyte, place in electrolytic cell and set aside;

[0122] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 340V positive voltage, 140V negative voltage, 500Hz frequency, 20% duty cycle, and 30min oxidation time. After checking that everything is correct, start oxidation;

[0123] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0124] 8) The weight gain of the generated base layer is 0.0597 g, and the unit weight gain is 18.66×10 3 g·m -3 ;

[0125] (2) Friction and wear test:

[0126] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0127] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0128] The experimental results show that the tribological properties of the TC4 alloy sample with only micro-arc oxidation coating as the base layer are as follows: at room temperature, the friction coefficient of the coating is about 0.22, and the wear amount is 0.0203g; at 300℃, the friction coefficient of the coating is about 0.30, and the wear amount is 0.0169g; at 400℃, the friction coefficient of the coating is about 0.32, and the wear amount is 0.0169g;

[0129] Comparative Example 3

[0130] A method for preparing a micro-arc oxidation coating on a titanium alloy surface:

[0131] (1) Preparation of base layer:

[0132] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40mm×40mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0133] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0134] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0135] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0136] 5) Prepare electrolyte: Prepare electrolyte with sodium silicate Na2SiO3·9H2O (30 g / L), sodium hexametaphosphate (NaPO3)6 (15 g / L), sodium molybdate Na2MoO4 (2 g / L), and potassium hydroxide KOH (2 g / L) as electrolyte, place in electrolytic cell and set aside;

[0137] 6) Micro-arc oxidation: Place the polished substrate in the prepared electrolyte, connect the substrate to the positive pole of the power supply, and connect the electrolytic cell to the negative pole of the power supply; adjust the oxidation power supply parameters to 380V positive voltage, 60V negative voltage, 300Hz frequency, 30% duty cycle, and 10min oxidation time. After checking that everything is correct, start oxidation;

[0138] 7) Weighing and measuring after cleaning: Rinse the oxidized substrate with deionized water and then ultrasonically clean it in alcohol for 5 minutes. After weighing it using an analytical balance, measure the sample thickness and film thickness at five different points using a micrometer and eddy current thickness gauge, and take the average value. Set the sample aside for later use.

[0139] 8) The resulting base layer gained 0.0571 g, with a unit weight gain of 17.84 × 10 3 g·m -3 ;

[0140] (2) Friction and wear test:

[0141] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0142] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh;

[0143] The experimental results show that the tribological properties of the TC4 alloy specimen with only micro-arc oxidation coating as the base layer are as follows: at room temperature, the friction coefficient of the coating is about 0.32, and the wear amount is 0.0209g; at 300℃, the friction coefficient of the coating is about 0.38, and the wear amount is 0.0175g; at 400℃, the friction coefficient of the coating is about 0.55, and the wear amount is 0.0137g.

[0144] Comparative Example 4

[0145] Friction and wear test of TC4 substrate:

[0146] (1) TC4 pretreatment steps are:

[0147] 1) Inspection and drilling of incoming parts: Check whether there are cracks or other defects on the surface of the substrate, make the substrate into a 40×40×2mm square plate and drill holes on the top of the substrate to prepare for subsequent processing;

[0148] 2) Grinding the substrate: Grind the substrate with 180#, 320#, 600#, 800#, or 1000# sandpaper;

[0149] 3) Cleaning: Place the polished substrate in alcohol and ultrasonically clean it for 5 minutes to remove surface dirt;

[0150] 4) Weighing: Weigh the substrate using an analytical balance and set aside;

[0151] (2) Friction and wear test:

[0152] 1) Using ball-on-disc friction, the friction pair is GCR15 bearing steel ball. The sample is rubbed for 30 minutes at room temperature, a load of 20N, and a rotation speed of 150rad / min.

[0153] 2) Weighing after cleaning: Place the sample in deionized water and ultrasonicate for 5 minutes, blow dry with cold air, and then weigh it.

[0154] The experimental results show that the tribological properties of the TC4 substrate are as follows: at room temperature, the friction coefficient of the coating is about 0.45, and the wear amount is 0.0146g; at 300°C, the friction coefficient of the coating is about 0.60, and the wear amount is 0.0108g; at 400°C, the friction coefficient of the coating is about 0.30, and the wear amount is -0.0006g.

[0155] Table 1 is a comparison table of average friction coefficients of the samples of Examples 1-3 and Comparative Examples 1-4 in friction and wear tests at room temperature, 300°C and 400°C.

[0156] Table 1

[0157]

[0158] The wear performance of Examples 1-3 and Comparative Examples 1-4 was evaluated using the weight loss method. Figure 1 The friction coefficient curves of the self-lubricating coatings prepared in Examples 1-3 and Comparative Examples 1-4 at room temperature are given. Figure 2 The friction coefficient curves of the self-lubricating coatings prepared in Examples 1-3 and Comparative Examples 1-4 at a high temperature of 300°C are given. Figure 3 The friction coefficient curves of the self-lubricating coatings prepared in Examples 1-3 and Comparative Examples 1-4 at a high temperature of 400°C are given. Table 1 shows the average friction coefficient and wear data of Examples 1-3 and Comparative Examples 1-4. Figure 1 As can be seen from Table 1, under normal temperature, the friction curve of the coating prepared by the method proposed by the present invention is smooth, and the friction coefficient is 0.06-0.09, which is about 13.3%-20.0% of the substrate, showing excellent self-lubricating properties. The friction curves of the coatings prepared by Comparative Examples 1-3 are extremely uneven, the average friction coefficient is increased, and the self-lubricating effect is poor. Figure 2 As can be seen from Table 1, under high temperature of 300°C, the friction curve of the coating prepared by the present invention is smooth, and the friction coefficient is 0.07-0.09, which is about 11.7%-15.0% of the substrate, showing excellent self-lubricating properties. The friction curves of the coatings prepared by Comparative Examples 1-3 are extremely uneven, the average friction coefficient is increased, and the self-lubricating effect is poor. Figure 3 As can be seen from Table 1, under high temperature of 400°C, the friction curve of the coating prepared by the present invention is smooth, and the friction coefficient is 0.07-0.19, which is about 23.3%-63.3% of the substrate, showing excellent self-lubricating properties. The friction curves of the coatings prepared in Comparative Examples 1-3 are extremely uneven, the average friction coefficient is increased, and the self-lubricating effect is poor.

[0159] Figure 41-3 are macromorphological photographs of the self-lubricating coatings in different stages. In the figure, (a1), (b1) and (c1) are macromorphological photographs of the base layer in Example 1, Example 2 and Example 3, respectively; (a2), (b2) and (c2) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3, respectively; (a3), (b3) and (c3) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after room temperature friction test, (a4), (b4) and (c4) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after 300°C friction test, (a5), (b5) and (c5) are macromorphological photographs of the self-lubricating coatings in Example 1, Example 2 and Example 3 after 400°C friction test, respectively; Figure 4 It can be seen that the surface of the ceramic coating is relatively rough. After adding the self-lubricating coating, the surface micropores are filled, the surface is glossy, and the flatness is improved. After the friction and wear test, there are slight wear marks on the surface, indicating that its self-lubricating effect is good under the conditions of room temperature to 400℃.

[0160] Figure 5 The macromorphology photos of the final samples of Comparative Examples 1-4 at different stages are shown in the figure. In the figure, (a1), (b1), (c1) and (d1) are respectively macromorphology photos of the sample surfaces of Comparative Examples 1-4, (a2), (b2), (c2) and (d2) are respectively macromorphology photos of the surfaces of the samples of Comparative Examples 1-4 after room temperature friction test, (a3), (b3), (c3) and (d3) are respectively macromorphology photos of the surfaces of the samples of Comparative Examples 1-4 after 300°C friction test, (a4), (b4), (c4) and (d4) are respectively macromorphology photos of the surfaces of the samples of Comparative Examples 1-4 after 400°C friction test. Figure 5 It can be seen that the wear scar depth of the TC4 substrate and the ceramic coating surface without the self-lubricating coating was higher when rubbed at room temperature to 400°C, and the ceramic coating surface without the self-lubricating coating was worn through, indicating that its self-lubricating performance was poor.

Claims

1. A method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface, characterized in that: The steps include: Step 1: preparing a base layer: preparing a micro-arc oxidation coating on the surface of the titanium alloy; Step 2, preparing a self-lubricating coating: spraying an emulsion on the surface of the micro-arc oxidation coating and curing it to obtain a self-lubricating coating, wherein the emulsion is a mixture of polyvinyl alcohol, molybdenum disulfide particles and deionized water, the mass percentage of the polyvinyl alcohol is 1-3%, and the concentration of the molybdenum disulfide particles is 3-9 g / L.

2. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The specific steps of step 1 are as follows: Step 1.1: Grind the surface of the titanium alloy to remove rust and make the surface of the titanium alloy smooth; Step 1.2: After cleaning and drying the polished titanium alloy, the alloy is placed in an electrolyte for micro-arc oxidation treatment to obtain the micro-arc oxidation coating, wherein the micro-arc oxidation treatment adopts a bidirectional pulsed AC voltage with a forward voltage of 300-380V, a negative voltage of 60-140V, a pulse frequency of 100-500Hz, a duty cycle of 10-30%, and an oxidation time of 10-50min.

3. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 2, characterized in that: In step 1.2, the electrolyte composition of micro-arc oxidation is as follows: Na2SiO3·9H2O: 10-30 g / L; (NaPO3)6: 5-15 g / L; Na2MoO4: 2-6 g / L; KOH: 2-6 g / L.

4. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: The thickness of the micro-arc oxidation coating is 23.4-33.8 μm.

5. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: Before spraying the emulsion, the method also includes a step of cleaning the surface of the micro-arc oxidation coating.

6. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: In step 2, the emulsion is sprayed 1-5 times, and is cured after each spraying.

7. The method for preparing a wide temperature range self-lubricating coating on a titanium alloy surface according to claim 1, characterized in that: In step 2, the curing method is to air-dry under natural conditions.

8. A wide temperature range self-lubricating coating on titanium alloy surface, characterized in that: The titanium alloy surface self-lubricating coating is prepared by the method for preparing a wide temperature range self-lubricating coating on the titanium alloy surface according to any one of claims 1 to 7.

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