Laser grinding composite processing preparation method of titanium alloy wear-resistant and friction-reducing surface

Abstract

The application discloses a kind of laser grinding composite processing preparation methods of titanium alloy wear-resistant friction-reducing surface, comprising the following steps: step one: polishing: after polishing treatment, titanium alloy sample is ultrasonic cleaned;Step two: surface modification: titanium alloy sample is placed on ultra-short pulse laser processing platform, and laser modification treatment is carried out to titanium alloy sample surface, so that titanium alloy sample surface material is modified to generate TiO2 Ceramic modification layer in situ under the action of laser;Step three: grinding and polishing: titanium alloy sample is placed on abrasive belt grinding processing platform, and titanium alloy sample is ground and polished, to remove the defects on the surface of TiO2 Ceramic modification layer and obtain a finished surface;Step four: ultrasonic cleaning: titanium alloy sample is ultrasonic cleaned, and titanium alloy sample with wear-resistant friction-reducing surface is obtained.The application can improve the hardness and wear resistance of titanium alloy wear-resistant friction-reducing surface, and reduce the friction coefficient of titanium alloy wear-resistant friction-reducing surface, to improve service life and reliability.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy surface modification technology, specifically a laser grinding composite processing method for preparing wear-resistant and friction-reducing titanium alloy surfaces. Background Technology

[0002] Titanium alloys possess numerous physical and chemical advantages, including low density, high specific strength, corrosion resistance, good biocompatibility, and strong processing properties, making them widely used in important engineering fields such as aerospace, marine, petrochemical, and biomedicine. However, the relatively low hardness and plastic shear resistance of titanium alloys make them prone to adhesive wear and abrasive wear during friction and wear processes. The poor tribological properties of titanium alloys limit their application in extreme service environments such as high loads, high speeds, and high friction. Therefore, improving the hardness of titanium alloy materials and enhancing their tribological properties has significant practical value.

[0003] Various surface coating 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 anodizing. These methods have solved the problem in certain application scenarios. However, the aforementioned methods require stringent preparation conditions and additive control. In addition, the oxide modified layers prepared by the aforementioned methods have disadvantages such as small thickness, easy presence of voids, increased surface roughness, and susceptibility to cracking and detachment between the substrate and the modified layer, which cannot meet the requirements 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 method for preparing wear-resistant and friction-reducing surfaces of titanium alloys, which can improve the hardness and wear resistance of the wear-resistant and friction-reducing surfaces of titanium alloys and reduce the coefficient of friction of the wear-resistant and friction-reducing surfaces of titanium alloys, thereby improving service life and reliability.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

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

[0007] Step 1: Grinding and Polishing

[0008] The titanium alloy sample was 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 a TiO2 ceramic modified layer under the action of laser.

[0011] Step 3: Grinding and Polishing

[0012] The titanium alloy sample was placed on a belt grinding platform and ground and polished to remove defects on the surface of the TiO2 ceramic modified layer and obtain a smooth surface.

[0013] Step 4: Ultrasonic Cleaning

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

[0015] Furthermore, in step one, the method for grinding and polishing the titanium alloy sample using a metallographic polishing machine is as follows:

[0016] 11) The titanium alloy sample was ground sequentially using SiC sandpaper of 400#, 800#, 1200#, 1500# and 2000#.

[0017] 12) Polish the surface of the titanium alloy sample to a surface roughness of less than 0.1 μm using a polishing cloth and diamond polishing paste;

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

[0019] Furthermore, in step two, the method for surface modification of the titanium alloy sample using a picosecond pulsed laser is as follows:

[0020] The laser power is set to 12W, the laser frequency to 700kHz, and the scanning speed to 5mm / s.

[0021] The laser wavelength was set to 1064nm, the pulse width to <15ps, and the spot diameter to 30μm.

[0022] The laser scanning path is set to reciprocating continuous scanning with a path interval of 30μm to achieve laser coverage irradiation of the processing area.

[0023] The surface material of the titanium alloy sample was modified in situ under laser treatment to form a TiO2 ceramic modified layer, and the thickness of the TiO2 ceramic modified layer was greater than or equal to 100 μm, and the hardness of the TiO2 ceramic modified layer was greater than or equal to 30 GPa.

[0024] Furthermore, the method for grinding and polishing titanium alloy samples using alumina pyramid abrasive belts is as follows:

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

[0026] The grinding depth was set to 50 μm to remove surface defects in the TiO2 ceramic modified layer;

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

[0028] The beneficial effects of this invention are as follows:

[0029] This invention discloses a laser grinding composite processing method for preparing wear-resistant and friction-reducing surfaces of titanium alloys. The method involves laser modification of the titanium alloy sample surface using a high energy rate density pulsed beam. The extremely high temperature and intense physicochemical reactions melt, evaporate, and oxidize the material, altering its microstructure, material properties, and mechanical properties, thus significantly improving the surface hardness and wear resistance of the titanium alloy. Under laser modification, a TiO2 ceramic modified layer is formed in situ on the surface of the titanium alloy sample. The TiO2 ceramic modified layer and the titanium alloy sample substrate are metallurgically bonded, avoiding the cracking and detachment problems common in existing technologies where external coatings adhere to the substrate. Furthermore, the thick TiO2 ceramic modified layer provides long-term wear resistance, and the TiO2 ceramic modified layer greatly improves the microhardness of the titanium alloy surface, thereby enhancing its wear resistance. However, as hardness and wear resistance increase, the surface morphology and surface roughness of titanium alloy samples become worse, and the coefficient of friction increases. This invention solves the problems of high surface roughness and high coefficient of friction after laser modification by grinding and polishing the TiO2 ceramic modified layer on the surface of the titanium alloy sample, while removing the defects on the surface of the TiO2 ceramic modified layer, thus improving the service life and reliability of the titanium alloy sample in a wear service environment.

[0030] In summary, the laser grinding composite processing method for preparing wear-resistant and friction-reducing surfaces of titanium alloys of this invention has the advantages of simplicity, environmental friendliness, and low cost, and can be widely used. This method combines the oxidation modification effect of high-energy-density ultrashort pulse lasers with the high-performance polishing effect of belt grinding. When applied to titanium alloys, it solves the problems of low hardness and poor wear resistance of titanium alloys, as well as the problems of high surface roughness, high friction coefficient, and surface defects after laser modification. The titanium alloy surface prepared by this method possesses both wear resistance and friction-reducing properties, expanding the application range of titanium alloys and making their service more reliable. Attached Figure Description

[0031] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration:

[0032] Figure 1 This is a flowchart of the laser grinding composite processing method for preparing wear-resistant and friction-reducing titanium alloy surfaces according to the present invention;

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

[0034] Figure 3 This is a surface morphology image after laser modification treatment;

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

[0036] Figure 5 XPS analysis results of Ti element in the oxide-modified layer;

[0037] Figure 6 The image shows the XRD analysis results of the oxidized modified layer.

[0038] Figure 7 The image shows the microhardness test results for the wear-resistant and friction-reducing surface.

[0039] Figure 8 Figure 1 shows the results of friction and wear tests on the wear-resistant and friction-reducing surface; where (a) is the curve of wear depth as a function of friction length; and (b) is the curve of friction coefficient as a function of friction length.

[0040] Figure 9 The images show the surface and cross-sectional morphology of the wear-resistant and friction-reducing surfaces after friction and wear. Among them, (a) is a SEM image of the wear morphology of a conventional titanium alloy surface; (b) is a SEM image of the wear morphology of the wear-resistant and friction-reducing surface; (c) is a SEM image of the wear cross-sectional morphology of a conventional titanium alloy; and (d) is a SEM image of the wear cross-sectional morphology of the wear-resistant and friction-reducing surface. Detailed Implementation

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

[0042] like Figure 1 As shown in the figure, the laser grinding composite processing method for preparing 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 was polished and then ultrasonically cleaned. In this embodiment, a metallographic polishing machine was used to grind and polish the titanium alloy sample. Specifically, the method and steps for grinding and polishing the titanium alloy sample using a metallographic polishing machine are as follows.

[0045] 11) The titanium alloy sample was ground in sequence using SiC sandpaper of 400#, 800#, 1200#, 1500# and 2000#.

[0046] 12) Polish the surface of the titanium alloy sample to a surface roughness of less than 0.1 μm using a polishing cloth and diamond polishing paste.

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

[0048] Step 2: Surface Modification

[0049] A titanium alloy sample is placed on an ultrashort pulse laser processing platform to perform laser modification treatment on its surface, causing in-situ modification of the surface material to form a TiO2 ceramic modification layer under laser irradiation. In this embodiment, a picosecond pulse laser is used for surface modification treatment of the titanium alloy sample. Specifically, the method for surface modification treatment of the titanium alloy sample using a picosecond pulse laser is as follows:

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

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

[0052] The laser scanning path is set to reciprocating continuous scanning with a path interval of 30μm to achieve comprehensive laser irradiation of the processing area. Figure 2 As shown.

[0053] The surface material of the titanium alloy sample was modified in situ under laser treatment to form a TiO2 ceramic modified layer, and the thickness of the TiO2 ceramic modified layer was greater than or equal to 100 μm, and the hardness of the TiO2 ceramic modified layer was greater than or equal to 30 GPa.

[0054] Step 3: Grinding and Polishing

[0055] The titanium alloy sample was placed on a belt grinding platform and ground and polished to remove defects on the surface of the TiO2 ceramic modified layer and obtain a smooth surface. In this embodiment, an alumina pyramid belt was used to grind and polish the titanium alloy sample. Specifically, 237AA-A65 alumina pyramid belt was used in this embodiment. The specific method for grinding and polishing the titanium alloy sample using the alumina pyramid 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 surface defects in the TiO2 ceramic modified layer.

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

[0059] Step 4: Ultrasonic cleaning

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

[0061] The technical effects of the laser grinding composite processing method for preparing wear-resistant and friction-reducing titanium alloy surfaces of the present invention will be explained below through sample characterization.

[0062] 1. Surface morphology after laser modification

[0063] The surface SEM morphology of the titanium alloy sample after laser modification is shown below. Figure 3 As shown, after laser modification, a large number of deposited particles remain on the surface, resulting in high surface roughness, which fails to meet the requirement for a low coefficient of friction.

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

[0065] SEM morphology of the surface and cross-section after belt grinding is as follows: Figure 4 As shown. From Figure 4 From (a), it can be concluded that after grinding and polishing, the deposits and defects on the surface are removed, the surface roughness is reduced, and the coefficient of friction is decreased. Figure 4 As can be seen in (b), the TiO2 ceramic modified layer generated in situ by laser modification is connected to the substrate through metallurgical transition. After 50μm is removed by belt grinding and polishing, the thickness of the modified layer is still about 50μm.

[0066] 3. Chemical state analysis of the oxidized modified layer

[0067] XPS analysis results of Ti element in the oxide-modified layer are as follows: Figure 5 As shown. From Figure 5 It can be seen that the Ti element in the modified layer has undergone complete oxidation modification and exists in the form of TiO2 metal oxide ceramic.

[0068] 4. Phase analysis of the oxidation-modified layer

[0069] XRD phase diagram of the oxidized modified layer as follows Figure 6 As shown. From Figure 6 It can be seen that TiO2 in the TiO2 ceramic modified layer exists in two forms, namely rutile TiO2 and anatase TiO2.

[0070] 5. Surface hardness analysis

[0071] Nanoindentation test results and microhardness of wear-resistant and friction-reducing surfaces, as shown in... Figure 7 As shown. From Figure 7 It can be seen that the TiO2 ceramic modified layer greatly improves the microhardness of the surface, and 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 Experiment Analysis

[0073] The curves showing the changes in wear depth and friction coefficient with friction length are as follows: Figure 8 As shown. From Figure 8 As can be seen from (a), the wear-resistant and friction-reducing surface exhibits a significantly reduced wear depth compared to the conventional titanium alloy surface, demonstrating stronger wear resistance; from Figure 8 As can be seen from (b), the wear-resistant and friction-reducing surface has a smaller coefficient of friction than the conventional titanium alloy surface, and can maintain its low coefficient of friction and good friction reduction properties during wear.

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

[0075] Figure 9 These are SEM images of the surface and cross-section of a conventional titanium alloy surface and a wear-resistant, friction-reducing surface after wear. (Comparison) Figure 9 (a) and Figure 9 (b) It can be observed that the wear-resistant and friction-reducing surface does not undergo severe plastic deformation and material removal like the conventional titanium alloy surface, exhibiting good wear resistance. (Comparison) Figure 9 (c) and Figure 9 (d) It can be observed that the surface contour of conventional titanium alloys is severely worn and the subsurface structure exhibits significant plastic deformation, while the surface contour of the wear-resistant and friction-reducing sample is straight and can maintain good friction reduction properties for a long time. The oxide ceramic modified layer did not show significant damage, and the wear resistance is good. Therefore, the wear-resistant and friction-reducing surface prepared in this invention has significantly better wear resistance, friction reduction, and service life compared to the conventional titanium alloy surface.

[0076] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a wear-resistant and friction-reducing surface of titanium alloy by laser grinding composite processing, characterized in that: Includes the following steps: Step 1: Grinding and Polishing The titanium alloy sample was polished and then ultrasonically cleaned. Step 2: Surface Modification 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 a TiO2 ceramic modified layer under the action of laser. The TiO2 ceramic modified layer contains rutile and anatase TiO2 crystals and is metallurgically bonded to the titanium alloy matrix. Step 3: Grinding and Polishing The titanium alloy sample was placed on a belt grinding platform, and the surface of the TiO2 ceramic modified layer of the titanium alloy sample was ground and polished to remove defects on the surface of the TiO2 ceramic modified layer and obtain a smooth surface. Step 4: Ultrasonic Cleaning The titanium alloy sample was ultrasonically cleaned to obtain a titanium alloy sample with a wear-resistant and friction-reducing surface.

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

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

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

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