Laser grinding combined machining preparation method for wear-resistant and friction-reducing surface of titanium alloy

Abstract

The invention discloses a laser grinding combined machining preparation method for a titanium alloy wear-resisting and friction-reducing surface. The laser grinding combined machining preparation method comprises the following steps that 1, grinding and polishing are conducted, specifically, a titanium alloy sample is subjected to ultrasonic cleaning after being subjected to polishing treatment; the titanium alloy sample is placed on an ultra-short pulse laser machining platform, laser modification treatment is conducted on the surface of the titanium alloy sample, and the titanium alloy sample surface material is subjected to in-situ modification under the laser effect to generate a TiO2 ceramic modified layer; the titanium alloy sample is placed on an abrasive belt grinding machining platform, grinding and polishing are conducted on the titanium alloy sample, defects on the surface of the TiO2 ceramic modified layer are removed, and a smooth surface is obtained; and 4, ultrasonic cleaning is conducted, specifically, the titanium alloy sample is subjected to ultrasonic cleaning, and the titanium alloy sample with the wear-resisting and friction-reducing surface is obtained. The hardness and wear resistance of the titanium alloy wear-resistant and friction-reducing surface can be improved, the friction coefficient of the titanium alloy wear-resistant and friction-reducing surface is reduced, the service life is prolonged, and the reliability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy surface modification, and specifically relates to a laser grinding composite processing preparation method for a titanium alloy wear-resistant and friction-reducing surface. Background Art

[0002] Titanium alloys have many physical and chemical advantages such as low density, high specific strength, corrosion resistance, good biocompatibility and strong process performance. They are widely used in important engineering fields such as aerospace, ocean, petrochemical and biomedicine. However, the low hardness and plastic shear resistance of titanium alloys make them prone to adhesive wear and abrasive wear during friction and wear. The poor friction performance of titanium alloys limits their application in extreme service environments such as high load, high speed and high friction. Therefore, improving the hardness of titanium alloy materials and improving their tribological properties has important practical value.

[0003] A variety of surface coatings and surface modification methods to improve the hardness and wear resistance of titanium alloys have been explored and developed, including thermochemical surface treatment, plasma modification, physical or chemical vapor deposition, magnetron sputtering, thermal oxidation and electrochemical anodization. These methods solve this problem in certain application scenarios. However, the aforementioned methods require the use of strict preparation conditions and additive control. In addition, the oxide modified layer prepared by the aforementioned method has a small thickness and is prone to voids, and is also accompanied by increased surface roughness and the substrate and modified layer are prone to cracking and falling off, which cannot meet the needs of long-term wear service. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a laser grinding composite processing preparation method for the wear-resistant and friction-reducing surface of titanium alloy, which can improve the hardness and wear resistance of the wear-resistant and friction-reducing surface of titanium alloy, and reduce the friction coefficient of the wear-resistant and friction-reducing surface of titanium alloy, so as to improve the service life and reliability.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A laser grinding composite processing preparation method for a wear-resistant and friction-reducing surface of a titanium alloy comprises the following steps:

[0007] Step 1: Grinding and polishing

[0008] The titanium alloy specimens were polished and then ultrasonically cleaned;

[0009] Step 2: Surface modification

[0010] The titanium alloy sample was placed on an ultrashort pulse laser processing platform, and the surface of the titanium alloy sample was laser modified to generate TiO in situ under the action of laser. 2 Ceramic modified layer;

[0011] Step 3: Grinding and polishing

[0012] The titanium alloy sample was placed on the belt grinding platform and ground and polished to remove TiO 2 Defects on the surface of the ceramic modified layer and obtain a smooth surface;

[0013] Step 4: Ultrasonic cleaning

[0014] The titanium alloy sample is ultrasonically cleaned to obtain a titanium alloy sample with a wear-resistant and friction-reducing surface.

[0015] Further, in step 1, the method steps of grinding and polishing the titanium alloy sample using a metallographic polishing machine are as follows:

[0016] 11) Use 400#, 800#, 1200#, 1500# and 2000# SiC sandpaper to grind the titanium alloy specimens in sequence;

[0017] 12) Use polishing cloth and diamond polishing paste to polish the surface of the titanium alloy sample until the surface roughness is less than 0.1 μm;

[0018] 13) Use acetone as a cleaning agent to perform ultrasonic cleaning on the titanium alloy specimens to remove oil, dust and other attachments on the surface of the specimens.

[0019] Furthermore, in step 2, the method of using a picosecond pulse laser to perform surface modification treatment on the titanium alloy sample is:

[0020] Set the laser power to 12 W, the laser frequency to 700 kHz, and the scanning speed to 5 mm / s;

[0021] Set the laser wavelength to 1064nm, pulse width <15ps, and spot diameter to 30μm;

[0022] Set the laser scanning path to reciprocating continuous scanning with a path interval of 30 μm to achieve laser coverage of the processing area;

[0023] In-situ modification of titanium alloy sample surface material under laser action to generate TiO 2 Ceramic modified layer, and TiO 2 The thickness of the ceramic modified layer is greater than or equal to 100 μm, and the TiO 2 The hardness of the ceramic modified layer is greater than or equal to 30 GPa.

[0024] Further, the method of grinding and polishing the titanium alloy sample using the alumina pyramid abrasive belt is as follows:

[0025] Set the belt linear speed to 10m / s and the feed speed to 0.1mm / s;

[0026] The grinding depth was set to 50 μm to remove TiO 2 Surface defects of the ceramic modified layer;

[0027] The surface roughness of the titanium alloy sample after belt grinding and polishing is less than 0.1 μm to reduce the surface friction coefficient and enhance the surface anti-friction property.

[0028] The beneficial effects of the present invention are:

[0029] The laser grinding composite processing preparation method of the wear-resistant and friction-reducing surface of titanium alloy of the present invention performs laser modification treatment on the surface of titanium alloy sample. The surface laser modification treatment utilizes a pulse beam with high energy rate density to melt, evaporate and oxidize the material by means of extremely high temperature and intense physical and chemical action to change the microstructure, material properties and mechanical properties of the material, which can greatly improve the surface hardness and wear resistance of titanium alloy. Under the action of laser modification, a layer of TiO2 is generated in situ on the surface material of the titanium alloy sample. 2 Ceramic modified layer, TiO 2 The ceramic modified layer and the titanium alloy sample substrate are connected by metallurgical bonding, which avoids the problem of easy cracking and falling off of the bonding between the external coating and the substrate in the prior art. 2 The ceramic modified layer has a large thickness and has long-term wear resistance. 2 The ceramic modified layer greatly improves the microhardness of the titanium alloy surface and improves the wear resistance of the titanium alloy. However, as the hardness and wear resistance are improved, the surface morphology and surface roughness of the titanium alloy sample become worse, and the friction coefficient increases. 2 The ceramic modified layer was ground and polished to solve the problems of high surface roughness and high friction coefficient after laser modification, while removing TiO 2 The defects on the surface of the ceramic modified layer improve the service life and reliability of the titanium alloy specimens in a wear service environment.

[0030] In summary, the laser grinding composite processing preparation method of the wear-resistant and friction-reducing surface of titanium alloy of the present invention has the advantages of being simple, environmentally friendly and low-cost, and can be widely used; the laser grinding composite processing preparation method of the wear-resistant and friction-reducing surface of titanium alloy of the present invention combines the oxidation modification of high-energy-density ultrashort pulse laser and the high-performance polishing effect of abrasive belt grinding, and is applied to titanium alloy, which not only solves the problems of low hardness and poor wear resistance of titanium alloy, but also solves the problems of high surface roughness, large friction coefficient and surface defects of titanium alloy after laser modification. The titanium alloy surface prepared by this method has both wear resistance and friction reduction, which expands the application range of titanium alloy and makes it more reliable in service. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0032] Figure 1 It is a flow chart of the laser grinding composite processing preparation method of the wear-resistant and friction-reducing surface of titanium alloy of the present invention;

[0033] Figure 2 is a schematic diagram of the laser scanning path;

[0034] Figure 3 This is the surface morphology after laser modification;

[0035] Figure 4 The surface and cross-sectional morphology images after belt grinding; (a) is the SEM image of the surface morphology of the sample after belt grinding and polishing; (b) is the SEM image of the cross-sectional morphology of the sample after belt grinding and polishing;

[0036] Figure 5 This is the XPS analysis result of Ti element in the oxidation modified layer;

[0037] Figure 6 This is the XRD analysis result of the oxidation modified layer;

[0038] Figure 7 This is the microhardness test result of the wear-resistant and friction-reducing surface;

[0039] Figure 8 The friction and wear test results of the wear-resistant and friction-reducing surface are shown in FIG. 1 , wherein (a) is the curve showing the variation of the wear depth with the friction length; (b) is the curve showing the variation of the friction coefficient with the friction length;

[0040] Fig. 9 The surface and cross-sectional morphologies of the wear-resistant and anti-friction surface after friction and wear; among them, (a) is the wear morphology SEM image of the conventional titanium alloy surface; (b) is the wear morphology SEM image of the wear-resistant and anti-friction surface; (c) is the wear cross-sectional morphology SEM image of the conventional titanium alloy; (d) is the wear cross-sectional morphology SEM image of the wear-resistant and anti-friction surface. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0042] like Figure 1 As shown, the laser grinding composite processing preparation method for the wear-resistant and friction-reducing surface of titanium alloy in this embodiment includes the following steps.

[0043] Step 1: Grinding and polishing

[0044] The titanium alloy sample is polished and then ultrasonically cleaned. In this embodiment, a metallographic polishing machine is used to grind and polish the titanium alloy sample. Specifically, the method steps of grinding and polishing the titanium alloy sample using a metallographic polishing machine are as follows.

[0045] 11) Use 400#, 800#, 1200#, 1500# and 2000# SiC sandpaper to grind the titanium alloy specimens in sequence.

[0046] 12) Use polishing cloth and diamond polishing paste to polish the surface of the titanium alloy sample until the surface roughness is less than 0.1 μm.

[0047] 13) Use acetone as a cleaning agent to perform ultrasonic cleaning on the titanium alloy specimens to remove oil, dust and other attachments on the surface of the specimens.

[0048] Step 2: Surface modification

[0049] The titanium alloy sample was placed on an ultrashort pulse laser processing platform, and the surface of the titanium alloy sample was laser modified to generate TiO in situ under the action of laser. 2 Ceramic modified layer. In this embodiment, a picosecond pulse laser is used to perform surface modification on a titanium alloy sample. Specifically, the method of using a picosecond pulse laser to perform surface modification on a titanium alloy sample is as follows:

[0050] Set the laser power to 12 W, the laser frequency to 700 kHz, and the scanning speed to 5 mm / s.

[0051] The laser wavelength was set to 1064 nm, the pulse width was <15 ps, and the spot diameter was 30 μm.

[0052] Set the laser scanning path to reciprocating continuous scanning, with a path interval of 30 μm, to achieve laser coverage of the processing area. Figure 2 shown.

[0053] In-situ modification of titanium alloy sample surface material under laser action to generate TiO 2 Ceramic modified layer, and TiO 2 The thickness of the ceramic modified layer is greater than or equal to 100 μm, and the TiO 2 The hardness of the ceramic modified layer is greater than or equal to 30 GPa.

[0054] Step 3: Grinding and polishing

[0055] The titanium alloy sample was placed on the belt grinding platform and ground and polished to remove TiO 2The defects on the surface of the ceramic modified layer are removed and a smooth surface is obtained. In this embodiment, an aluminum oxide pyramid abrasive belt is used to grind and polish the titanium alloy sample. Specifically, the aluminum oxide pyramid abrasive belt in this embodiment uses a 237AA-A65 aluminum oxide pyramid abrasive belt. Specifically, the method for grinding and polishing the titanium alloy sample using an aluminum oxide pyramid abrasive belt is as follows:

[0056] Set the belt linear speed to 10 m / s and the feed speed to 0.1 mm / s.

[0057] The grinding depth was set to 50 μm to remove TiO 2 Surface defects of ceramic modified layer.

[0058] The surface roughness of the titanium alloy sample after belt grinding and polishing is less than 0.1 μm to reduce the surface friction coefficient, enhance the surface anti-friction property, and obtain a smooth surface with a low friction coefficient.

[0059] Step 4: Ultrasonic cleaning

[0060] The titanium alloy sample is ultrasonically cleaned to obtain a titanium alloy sample with a wear-resistant and friction-reducing surface.

[0061] The technical effect of the laser grinding composite processing preparation method for the wear-resistant and friction-reducing surface of titanium alloy of the present invention is described below through sample characterization.

[0062] 1. Surface morphology after laser modification

[0063] The surface SEM morphology of titanium alloy samples after laser modification is as follows: Figure 3 After laser modification, there are a lot of sediment particles on the surface, the surface roughness is high, and it cannot meet the requirements of low friction coefficient.

[0064] 2. Surface and cross-sectional morphology after belt grinding

[0065] The surface and cross-section SEM morphology after belt grinding is as follows Figure 4 As shown. Figure 4 It can be concluded from (a) that after grinding and polishing, the deposits and defects on the surface are removed, the surface roughness is reduced, and the friction coefficient is reduced. Figure 4 As can be seen in (b), the TiO generated in situ by laser modification 2 The ceramic modified layer and the substrate are connected through metallurgical transition. After 50 μm is removed by belt grinding and polishing, the thickness of the modified layer is still about 50 μm.

[0066] 3. Chemical state analysis of oxidation modified layer

[0067] The XPS analysis results of Ti element in the oxidized modified layer are as follows: Figure 5 As shown. Figure 5It can be seen that the Ti element in the modified layer is completely oxidized and modified to TiO 2 Metal oxide ceramics exist.

[0068] 4. Phase analysis of oxidation modified layer

[0069] The XRD phase spectrum of the oxidized modified layer is as follows: Figure 6 As shown. Figure 6 It can be obtained that TiO 2 TiO in ceramic modified layer 2 There are two forms, namely rutile TiO 2 (Rutile-TiO 2 ) and anatase TiO 2 (Anatase-TiO 2 ).

[0070] 5. Surface hardness analysis

[0071] Nanoindentation test results and microhardness of wear-resistant and friction-reducing surfaces Figure 7 As shown. Figure 7 It can be obtained that TiO 2 The ceramic modified layer greatly improves the microhardness of the surface. The microhardness of the wear-resistant and friction-reducing surface reaches 35.01 GPa, which is about 10 times higher than that of conventional titanium alloy surfaces.

[0072] 6. Friction and wear experimental analysis

[0073] The variation curves of wear depth and friction coefficient with friction length are shown in Figure 8 As shown. Figure 8 It can be seen from (a) that the wear depth of the wear-resistant and friction-reducing surface is significantly reduced compared with the conventional titanium alloy surface, and it has stronger wear resistance; Figure 8 As can be seen in (b), the wear-resistant and anti-friction surface has a smaller friction coefficient than that of the conventional titanium alloy surface, and can maintain its low friction coefficient and good anti-friction properties during wear.

[0074] 7. Friction and wear surface and cross-sectional morphology

[0075] Fig. 9 The surface and cross-sectional SEM images of the conventional titanium alloy surface and the wear-resistant and anti-friction surface after wear. Fig. 9 (a) and Fig. 9 (b) It can be found that the wear-resistant and friction-reducing surface does not undergo severe plastic deformation and material removal like the conventional titanium alloy surface, and the surface has good wear resistance. Fig. 9 (c) and Fig. 9(d) It can be found that the surface profile of the conventional titanium alloy is severely worn and the subsurface structure has obvious plastic deformation, while the surface profile of the wear-resistant and anti-friction sample is straight, and can maintain good anti-friction properties for a long time. The oxide ceramic modified layer has no obvious damage and has good wear resistance. Therefore, the wear-resistant and anti-friction surface prepared by the present invention has significant wear resistance, anti-friction properties and service life compared with the conventional titanium alloy surface.

[0076] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A laser grinding composite processing method for preparing a wear-resistant and friction-reducing surface of a titanium alloy, characterized in that: The steps include: Step 1: Grinding and polishing The titanium alloy specimens were polished and then ultrasonically cleaned; Step 2: Surface modification The titanium alloy sample is placed on an ultrashort pulse laser processing platform, and the surface of the titanium alloy sample is laser modified, so that the surface material of the titanium alloy sample is in-situ modified under the action of laser to generate a TiO2 ceramic modified layer; Step 3: Grinding and polishing The titanium alloy sample is placed on a belt grinding processing platform, and the titanium alloy sample is ground and polished to remove the defects on the surface of the TiO2 ceramic modified layer and obtain a smooth surface; Step 4: Ultrasonic cleaning The titanium alloy sample is ultrasonically cleaned to obtain a titanium alloy sample with a wear-resistant and friction-reducing surface.

2. The laser grinding composite processing method for preparing the wear-resistant and friction-reducing surface of titanium alloy according to claim 1, characterized in that: In the step 1, the method steps of grinding and polishing the titanium alloy sample using a metallographic polishing machine are as follows: 11) Use 400#, 800#, 1200#, 1500# and 2000# SiC sandpaper to grind the titanium alloy specimens in sequence; 12) Use polishing cloth and diamond polishing paste to polish the surface of the titanium alloy sample until the surface roughness is less than 0.1 μm; 13) Use acetone as a cleaning agent to perform ultrasonic cleaning on the titanium alloy specimens to remove oil, dust and other attachments on the surface of the specimens.

3. The laser grinding composite processing method for preparing the wear-resistant and friction-reducing surface of titanium alloy according to claim 1, characterized in that: In the step 2, the method of using a picosecond pulse laser to perform surface modification on the titanium alloy sample is: Set the laser power to 12 W, the laser frequency to 700 kHz, and the scanning speed to 5 mm / s; Set the laser wavelength to 1064nm, pulse width <15ps, and spot diameter to 30μm; Set the laser scanning path to reciprocating continuous scanning with a path interval of 30 μm to achieve laser coverage of the processing area; The surface material of the titanium alloy sample is in-situ modified under the action of laser to generate a TiO2 ceramic modified layer, and the thickness of the TiO2 ceramic modified layer is greater than or equal to 100 μm, and the hardness of the TiO2 ceramic modified layer is greater than or equal to 30 GPa.

4. The laser grinding composite processing method for preparing the wear-resistant and friction-reducing surface of titanium alloy according to claim 1, characterized in that: The method for grinding and polishing titanium alloy specimens using alumina pyramid abrasive belts is as follows: Set the belt linear speed to 10m / s and the feed speed to 0.1mm / s; The grinding depth was set to 50 μm to remove the surface defects of the TiO2 ceramic modified layer; The surface roughness of the titanium alloy sample after belt grinding and polishing is less than 0.1 μm to reduce the surface friction coefficient and enhance the surface anti-friction property.

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