Form-Modulation Composite Treatment Method for Friction Reduction and Wear Resistance of Titanium Alloy Surface

Abstract

This invention discloses a form-property composite treatment method for reducing friction and improving wear resistance on titanium alloy surfaces, specifically implemented according to the following steps: Step 1, using photosensitive blue oil as an etchant, a microtexture is processed on the titanium alloy surface using wet etching technology; Step 2, the textured titanium alloy obtained in Step 1 is subjected to thermal oxidation treatment to obtain a form-property composite treated titanium alloy. This invention can achieve the synergistic effect of microtexturing and thermal oxidation, simultaneously improving the friction reduction and wear resistance properties of the titanium alloy surface, which helps to expand the application range of titanium alloys and extend the service life of titanium alloy parts under friction conditions.

Description

Technical Field

[0001] This invention belongs to the technical field of metal surface treatment methods, specifically relating to a composite treatment method for reducing friction and increasing wear resistance on titanium alloy surfaces. Background Technology

[0002] Titanium alloys are widely used in aerospace, weaponry, and biomedicine due to their low density, high specific strength, and excellent corrosion resistance. However, their low surface hardness, high coefficient of friction, and poor wear resistance severely limit their use under friction conditions. Therefore, improving the friction-reducing and wear-resistant properties of titanium alloy surfaces is of great significance for expanding their application range and extending the service life of titanium alloy components. Surface microtextures have a friction-reducing effect, but the stress concentration at the texture edges is high, leading to severe wear. While thermal oxidation is a simple and economical method to improve the wear resistance of titanium alloys, the oxide layer has a high coefficient of friction and is prone to peeling, delamination, and even cracking. Combining surface microtextures with thermal oxidation technology allows the presence of texture to improve the depth and adhesion of the oxide layer, reducing oxide film peeling and delamination. The presence of the oxide film, in turn, can increase surface hardness and extend the service life of the texture.

[0003] Studies have shown that while surface microtexturing and thermal oxidation combined treatment can significantly improve the wear resistance of titanium alloys, it may not necessarily reduce the coefficient of friction at the same time. Achieving both friction reduction and wear resistance simultaneously through the combination of microtexturing and thermal oxidation is quite difficult, mainly depending on whether microtexturing and thermal oxidation can achieve synergistic effects. This involves many important parameters, such as the diameter, areal density, and depth of the microtexture, as well as the temperature and time of thermal oxidation.

[0004] In addition, current methods for processing microtextures on titanium alloy surfaces mainly rely on laser processing technology. However, when the material is ablated at high temperatures, it is easy to generate protrusions, slag, and other material accumulations at the edges of the micro-pits, resulting in unevenness and extremely high roughness at the bottom of the micro-pits. Furthermore, it can introduce significant thermal stress and thermal damage into the processing area. Moreover, it is inefficient and costly in the processing of large-area, large-scale microtextures. Summary of the Invention

[0005] The purpose of this invention is to provide a composite treatment method for reducing friction and improving wear resistance on titanium alloy surfaces, thereby solving the problem that existing technologies cannot simultaneously improve the friction reduction and wear resistance of titanium alloys through a combination of microtexturing and thermal oxidation treatments.

[0006] The technical solution of this invention is a composite treatment method for reducing friction and increasing wear resistance on titanium alloy surfaces, specifically implemented according to the following steps:

[0007] Step 1: Using photosensitive blue oil as an etchant, microtextures are fabricated on the surface of the titanium alloy using wet etching technology;

[0008] Step 2: Perform hot oxidation treatment on the textured titanium alloy obtained in Step 1 to obtain a titanium alloy with composite shape and properties.

[0009] The invention is further characterized by:

[0010] Step 1 is implemented in the following steps:

[0011] Step 1.1: Pre-treat the workpiece surface and coat it with blue oil;

[0012] Step 1.2: Perform pre-baking and prepare a homemade mask;

[0013] Step 1.3: Expose and develop the mask from Step 1.2;

[0014] Step 1.4: Perform post-baking and etching.

[0015] Step 1.5: Demold the etched workpiece.

[0016] Step 1.1 is as follows: Mechanically polish the titanium alloy workpiece, clean it, and blow it dry for later use. Then, use a scraping or spraying method to evenly coat the surface of the dried titanium alloy workpiece with photosensitive blue oil. The thickness of the blue oil is 0.2mm to 0.6mm. After coating, let it stand in a cool place for no less than 30 minutes.

[0017] Step 1.2 specifically involves: transferring the titanium alloy workpiece coated with photosensitive blue oil to a drying oven at a temperature of 50℃~60℃ and keeping it at that temperature for 24~48h until the photosensitive blue oil dries; then drawing a two-dimensional microtexture pattern according to the required microtexture parameters; and then using a printer to make a film mask, with the textured part being a black light-absorbing layer and the rest being a light-transmitting layer.

[0018] Step 1.3 is as follows: Place the prepared mask on the pre-baked workpiece and press it firmly with plexiglass. Then expose it with two or more ultraviolet lamps for 4 to 8 minutes at an exposure distance of 10 to 20 cm. After exposure, immerse the workpiece in the developer for 1 minute, then remove it and use a soft brush dipped in the developer to brush the surface of the photosensitive blue oil until the desired microtexture shape is fully revealed and there is no developer residue. After development, rinse the workpiece twice with deionized water.

[0019] Step 1.4 is as follows: Place the developed workpiece in a drying oven at a temperature of 50℃~60℃ for 20min~30min, then place the dried workpiece in a titanium alloy etching solution for etching. After etching, rinse the workpiece twice with deionized water.

[0020] Step 1.5 is as follows: After etching, the workpiece is immersed in the release solution for 5 to 10 minutes, and then the surface is gently brushed with a soft brush to remove the blue oil. After demolding, the workpiece is rinsed twice with deionized water and dried. The release solution is a sodium hydroxide solution prepared by mixing NaOH and deionized water at a weight ratio of 1:20, and the operating temperature is 38℃ to 45℃.

[0021] The developer is a sodium carbonate solution prepared by mixing NaCO3 and deionized water at a weight ratio of 1:100, and the operating temperature is 25℃~30℃.

[0022] Step 2 specifically involves placing the textured titanium alloy workpiece in a heating furnace and holding it at 700°C for 7 hours, then cooling it to room temperature with the furnace.

[0023] The present invention has the following beneficial effects:

[0024] 1) This invention can achieve the synergistic effect of microtexture and thermal oxidation, which can simultaneously improve the friction reduction and wear resistance of titanium alloy surfaces, and help expand the application range of titanium alloys and extend the service life of titanium alloy parts under friction conditions.

[0025] 2) This invention uses an etching microtexturing method based on photosensitive blue oil to process microtextures on the surface of titanium alloys. Especially in the processing of large surface areas and large scale microtextures, it has great advantages of low cost and high efficiency. Moreover, the bottom of the texture pits is flat and there is no thermal stress or thermal damage.

[0026] 3) This invention combines a low-cost microtexturing processing method based on photosensitive blue oil with a simple and economical thermal oxidation treatment to achieve a composite treatment of the shape and properties of titanium alloy surfaces. It has the advantages of simple equipment and low cost, and is suitable for mass production. Attached Figure Description

[0027] Figure 1 This is a surface morphology diagram of the composite treatment of etched microtexture and thermal oxidation according to the present invention;

[0028] Figure 2 This is a schematic diagram of the surface hardness after the composite treatment according to the present invention;

[0029] Figure 3 This is a graph showing the friction coefficient after the composite treatment according to the present invention;

[0030] Figure 4 This shows the wear mark morphology after composite treatment according to the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0032] The method for combined surface treatment of titanium alloys to reduce friction and improve wear resistance is implemented according to the following steps:

[0033] Step 1: Using photosensitive blue oil as an etchant, microtextures are fabricated on the surface of the titanium alloy using wet etching technology;

[0034] Step 1 is implemented in the following steps:

[0035] Step 1.1: Pre-treat the workpiece surface and coat it with blue oil;

[0036] Step 1.1 is as follows: Mechanically polish the titanium alloy workpiece, clean it and blow it dry for later use. Then, use a scraping or spraying method to evenly coat the surface of the dried titanium alloy workpiece with photosensitive blue oil. The thickness of the blue oil is 0.2mm to 0.6mm. After coating, let it stand in a cool place for no less than 30 minutes.

[0037] Step 1.2: Perform pre-baking and prepare a homemade mask;

[0038] Step 1.2 specifically involves: transferring the titanium alloy workpiece coated with photosensitive blue oil to a drying oven at a temperature of 50℃~60℃ and keeping it at that temperature for 24~48h until the photosensitive blue oil dries; then drawing a two-dimensional microtexture pattern according to the microtexture parameters to be prepared; and then using a printer to make a film mask, with the textured part being a black light-absorbing layer and the rest being a light-transmitting layer.

[0039] Step 1.3: Expose and develop the mask from Step 1.2;

[0040] Step 1.3 is as follows: Place the mask on the pre-baked workpiece and press it with plexiglass. Expose it with two or more UV lamps for 4 to 8 minutes at a distance of 10 to 20 cm. Then immerse the exposed workpiece in the developer for 1 minute. Remove it and use a soft brush dipped in the developer to brush the surface of the photosensitive blue oil until the desired microtexture shape is fully revealed and there is no developer residue. After development, rinse the workpiece twice with deionized water.

[0041] The developing solution is a sodium carbonate solution prepared by mixing NaCO3 and deionized water at a weight ratio of 1:100, and the operating temperature is 25℃~30℃.

[0042] Step 1.4: Perform post-baking and etching.

[0043] Step 1.4 is as follows: Place the developed workpiece in a drying oven at a temperature of 50℃~60℃ for 20min~30min, then place the dried workpiece in a titanium alloy etching solution for etching, and after etching, rinse the workpiece twice with deionized water.

[0044] The etching solution for titanium alloys is prepared by weight ratio of hydrofluoric acid: nitric acid: sodium dodecylbenzenesulfonate: deionized water = 32:55:0.1:413, and the operating temperature is within 25℃~30℃.

[0045] Step 1.5: Demold the etched workpiece;

[0046] Step 1.5 is as follows: After etching, the workpiece is immersed in the release solution for 5 to 10 minutes, and then the surface is gently brushed with a soft brush to remove the blue oil. After demolding, the workpiece is rinsed twice with deionized water and dried. The release solution is a sodium hydroxide solution prepared by mixing NaOH and deionized water at a weight ratio of 1:20, and the operating temperature is 38℃ to 45℃.

[0047] The release solution is a sodium hydroxide solution prepared by mixing NaOH and deionized water at a weight ratio of 1:20, and the operating temperature is 38℃~45℃.

[0048] Step 2: Perform hot oxidation treatment on the textured titanium alloy obtained in Step 1 to obtain a titanium alloy with composite shape and properties.

[0049] Step 2 is as follows: The textured titanium alloy workpiece is placed in a heating furnace and heated from room temperature to 500°C at a heating rate of 10°C / min. It is then held at 500°C for ten minutes, then heated to 700°C at a heating rate of 5°C / min. It is then held at 700°C for 7 hours and then cooled to room temperature with the furnace.

[0050] Example 1

[0051] The surface of the TC4 titanium alloy disc sample (size Φ30×8mm) was subjected to morphological composite treatment, specifically implemented according to the following steps:

[0052] Step 1: Using photosensitive blue oil as an etchant, microtextures are fabricated on the surface of the titanium alloy using wet etching technology;

[0053] Step 1.1, Pre-treatment of workpiece surface and application of blue oil: Mechanically polish the TC4 titanium alloy workpiece, clean it with acetone and alcohol in sequence using ultrasonic cleaning, and dry it with air blowing for later use; then use the scraping method to evenly apply photosensitive blue oil to the polished TC4 titanium alloy workpiece surface, with a blue oil thickness of 0.2mm, and let it stand in a cool place for 30 minutes after application.

[0054] Step 1.2, Pre-baking and self-made mask: Transfer the TC4 titanium alloy workpiece coated with photosensitive blue oil to a drying oven at 55℃ for 24 hours until the photosensitive blue oil is dry; then use CAD software to draw a two-dimensional micro-texture pattern with a diameter of 300μm and an area density of 26%; then use a regular printer to make a film mask, with the textured part being a black light-absorbing layer and the rest being a light-transmitting layer;

[0055] Step 1.3, Exposure and Development: Place the prepared mask on the pre-baked TC4 workpiece and press it firmly with plexiglass. Then expose it with two UV lamps for 4 minutes at a distance of 16 cm. After exposure, immerse the TC4 workpiece in the developer for 1 minute. Then remove it and use a soft brush dipped in the developer to brush the surface of the photosensitive blue oil until the desired microtexture shape is fully revealed and there is no developer residue. After development, rinse the workpiece twice with deionized water.

[0056] The developing solution is a sodium carbonate solution prepared by mixing NaCO3 and deionized water at a weight ratio of 1:100, and the operating temperature is 25℃.

[0057] Step 1.4, Post-baking and etching: Place the developed TC4 workpiece in a drying oven at 55℃ for 20 minutes; place the dried TC4 workpiece in a titanium alloy etching solution for 6 minutes; after etching, rinse the workpiece twice with deionized water.

[0058] Titanium alloy etching solution: by weight ratio, hydrofluoric acid: nitric acid: sodium dodecylbenzenesulfonate: deionized water = 32:55:0.1:413; operating temperature is 25℃, and the etching rate of TC4 titanium alloy is approximately 3.5 μm / min.

[0059] Step 1.5 Demolding: Immerse the etched workpiece in the demolding solution for 5 minutes, then gently brush the surface with a soft brush to remove the blue oil. After demolding, rinse the workpiece twice with deionized water and blow dry.

[0060] The release agent is a sodium hydroxide solution prepared by mixing NaOH and deionized water at a weight ratio of 1:20, and the operating temperature is 38℃.

[0061] Step 2: Perform hot oxidation treatment on the textured TC4 titanium alloy obtained in Step 1 to obtain a TC4 titanium alloy with composite shape and properties treatment.

[0062] Step 2 is as follows: The textured TC4 titanium alloy workpiece obtained in Step 1 is placed in a box-type resistance furnace. It is first heated from room temperature to 500°C at a heating rate of 10°C / min and held at 500°C for ten minutes. Then it is heated to 700°C at a heating rate of 5°C / min and held at 700°C for 7 hours. After that, it is cooled to room temperature with the furnace.

[0063] The shape-property composite treatment in this embodiment specifically involves "microtexture with an areal density of 26% + thermal oxidation," and its microstructure is shown in the attached figure. Figure 1 As shown in d; Vickers hardness test results (attached) Figure 2 The results show that the surface hardness after composite treatment is 2.69 times that of the TC4 substrate and 1.24 times that of the single thermal oxide layer, respectively; wear test results show (see attached...). Figure 3 The coefficient of friction after composite treatment (0.21) was reduced by 61.1% and 44.8% compared to TC4 substrate (0.54) and single thermal oxidation treatment (0.38), respectively; (Attached) Figure 4 The results show that during grinding with GCr15 steel balls, the TC4 substrate experienced severe abrasive wear, while the surfaces with a single thermal oxide layer and those after composite treatment showed almost no wear. Adhesive transfer between the grinding surfaces was the primary characteristic, accompanied by oxidative wear. Furthermore, compared to the single thermal oxide layer, the adhesive wear on the composite-treated surface was significantly reduced.

[0064] Example 2

[0065] The surface of the TC4 titanium alloy disc sample (size Φ30×8mm) underwent a shape-composite treatment, the specific steps of which were the same as in Example 1, with the following differences:

[0066] In step 1.2, a film mask with an areal density of 20% is prepared.

[0067] The shape-property composite treatment in this embodiment specifically involves "microtexturing with an areal density of 20% + thermal oxidation," and its microstructure is shown in the attached figure. Figure 1 As shown in c; Vickers hardness test results (attached) Figure 2 The results show that the surface hardness after composite treatment is 2.65 times that of the TC4 substrate and 1.22 times that of the single thermal oxide layer, respectively; wear test results show (see attached...). Figure 3 The coefficient of friction after composite treatment (0.46) was 14.8% lower than that of TC4 substrate (0.54), and 21.1% higher than that of single thermal oxidation treatment (0.38); (Attached) Figure 4 c indicates that when rubbing against GCr15 steel balls, the surface after composite treatment showed almost no wear, with adhesive transfer between the rubbing surfaces being the primary mode of wear, accompanied by oxidative wear. The degree of adhesive wear after composite treatment is comparable to that of a single thermal oxide layer.

[0068] Example 3

[0069] The surface of the TC4 titanium alloy disc sample (size Φ30×8mm) underwent a shape-composite treatment, the specific steps of which were the same as in Example 1, with the following differences:

[0070] In step 1.2, a film mask with an areal density of 15% is prepared.

[0071] The shape-property composite treatment in this embodiment specifically involves "microtexturing with an areal density of 15% + thermal oxidation," and its microstructure is shown in the attached figure. Figure 1 As shown in b; Vickers hardness test results (attached) Figure 2 The results show that the surface hardness after composite treatment is 2.52 times that of the TC4 substrate and 1.17 times that of the single thermal oxide layer, respectively; wear test results show (see attached...). Figure 3The coefficient of friction (0.30) after composite treatment was reduced by 44.4% and 21.1% compared to TC4 substrate (0.54) and single thermal oxidation treatment (0.38), respectively; (Attached) Figure 4 b indicates that when grinding against GCr15 steel balls, the surface after composite treatment is almost not worn. The wear mechanism is mainly the adhesive transfer of the grinding pair, accompanied by oxidative wear, but its adhesive wear is significantly reduced compared to a single thermal oxide layer.

[0072] Example 4

[0073] The surface of the TC4 titanium alloy disc sample (size Φ30×8mm) underwent a shape-composite treatment, the specific steps of which were the same as in Example 1, with the following differences:

[0074] In step 1.2, a film mask with an area density of 8% is prepared.

[0075] The shape-property composite treatment in this embodiment is specifically "microtexture with an area density of 8% + thermal oxidation", and its microstructure is shown in the attached figure. Figure 1 As shown in a; Vickers hardness test results (attached) Figure 2 The results show that the surface hardness after composite treatment is 2.51 times that of the TC4 substrate and 1.16 times that of the single thermal oxide layer, respectively; wear test results show (see attached...). Figure 3 The coefficient of friction (0.35) after composite treatment was reduced by 35.2% and 7.9% compared to TC4 substrate (0.54) and single thermal oxidation treatment (0.38), respectively; (Attached) Figure 4 The results show that when grinding against GCr15 steel balls, the surface after composite treatment is almost not worn. The wear mechanism is mainly the adhesive transfer of the grinding pair, accompanied by oxidative wear. The degree of adhesive wear is slightly reduced compared to that of a single thermal oxide layer.

[0076] As can be seen from the above examples, the reduction in the coefficient of friction of the substrate after the composite treatment of etched microtextures with different areal densities and thermal oxidation is significantly different. In particular, the microtexture with an areal density of 26% combined with thermal oxidation has the best friction reduction and wear resistance, which greatly reduces the abrasive wear and adhesive wear of the titanium alloy substrate and the single thermal oxidation layer.

Claims

1. A method for combined surface treatment of titanium alloys to reduce friction and improve wear resistance, characterized in that... The specific steps are as follows: Step 1: Using photosensitive blue oil as an etchant, microtextures are fabricated on the surface of the titanium alloy using wet etching technology; Step 2: Perform hot oxidation treatment on the textured titanium alloy obtained in Step 1 to obtain a titanium alloy with composite shape and properties. Step 1 is implemented in the following steps: Step 1.1: Pre-treat the workpiece surface and coat it with blue oil; Step 1.2: Perform pre-baking and prepare a homemade mask; Step 1.3: Expose and develop the mask from Step 1.2; Step 1.4: Perform post-baking and etching. Step 1.5: Demold the etched workpiece; Step 1.1 specifically involves: mechanically polishing the titanium alloy workpiece, cleaning it, and drying it for later use. Then, using a scraping or spraying method, uniformly apply photosensitive blue oil to the surface of the dried titanium alloy workpiece. The thickness of the blue oil is 0.2 mm to 0.6 mm. After application, allow it to stand in a cool place for no less than 30 minutes. Step 1.2 specifically involves: transferring the titanium alloy workpiece coated with photosensitive blue oil to a drying oven at a temperature of 50℃~60℃ and keeping it at that temperature for 24~48h until the photosensitive blue oil dries; then drawing a two-dimensional microtexture pattern according to the microtexture parameters to be prepared; and then using a printer to make a film mask, with the textured part being a black light-absorbing layer and the rest being a light-transmitting layer. Step 1.3 specifically involves: placing the fabricated mask on the pre-baked workpiece and pressing it with plexiglass, then exposing it with two or more ultraviolet lamps for 4 to 8 minutes at an exposure distance of 10 to 20 cm. After exposure, the workpiece is immersed in the developing solution for 1 minute, then removed and brushed with a soft brush dipped in the developing solution on the surface of the photosensitive blue oil until the desired microtexture shape is fully revealed and there is no developing residue. After development, the workpiece is rinsed twice with deionized water. Step 1.4 specifically involves: placing the developed workpiece in a drying oven at a temperature of 50℃~60℃ for 20min~30min, then placing the dried workpiece in a titanium alloy etching solution for etching, and rinsing the workpiece twice with deionized water after etching. Step 1.5 specifically involves: immersing the etched workpiece in the release solution for 5-10 minutes, then gently brushing the surface with a soft brush to remove the blue oil. After demolding, rinse the workpiece twice with deionized water and blow dry. The release solution is a sodium hydroxide solution prepared by mixing NaOH and deionized water at a weight ratio of 1:20, and the operating temperature is 38℃-45℃. The developing solution is a sodium carbonate solution prepared by mixing NaCO3 and deionized water at a weight ratio of 1:100, and the operating temperature is 25℃~30℃. The titanium alloy etching solution is prepared by weight ratio of hydrofluoric acid: nitric acid: sodium dodecylbenzenesulfonate: deionized water = 32:55:0.1:413, and the operating temperature is within 25℃~30℃. Step 2 specifically involves placing the textured titanium alloy workpiece in a heating furnace and holding it at 700°C for 7 hours, then cooling it to room temperature with the furnace. The areal density of the microtexture is 26%.

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