Surface treatment method for titanium alloy 3D printed part

Abstract

The application provides a surface treatment method of a titanium alloy 3D printed part, and belongs to the technical field of surface treatment of 3D printed parts. The method comprises the following steps: sequentially performing first treatment and chemical polishing on the titanium alloy 3D printed part to obtain the printed part after surface treatment; the first treatment comprises sequentially performing chemical corrosion and micro-arc oxidation; the micro-arc oxidation adopts an electrolyte comprising the following concentration components: one or more of alkali metal hydroxide 1.5-50 g / L and zincate 0.5-8 g / L, phosphate 0.2-15 g / L and aluminate 0.5-5 g / L. The surface treatment method of the titanium alloy 3D printed part provided by the application can reduce the surface roughness of the titanium alloy 3D printed part.

Description

Technical Field

[0001] This application belongs to the field of 3D printed parts surface treatment technology, and more specifically, relates to a surface treatment method for titanium alloy 3D printed parts. Background Technology

[0002] Titanium alloys, due to their high specific strength, excellent corrosion resistance, and biocompatibility, have become the primary materials in aerospace, medical implants, and other fields. 3D printing technology can directly manufacture complex, lightweight titanium alloy components and achieve internal flow path structures that are impossible to form using traditional machining, thus broadening the application range of titanium alloys. However, the stacking effect and powder adhesion that occur during the 3D printing process result in significant surface roughness in 3D printed parts, especially in internal flow paths.

[0003] High surface roughness in 3D printed parts, especially those with internal flow paths, not only affects appearance but also negatively impacts properties such as fatigue strength, corrosion resistance, and biocompatibility. For example, a rough surface can induce stress concentration, becoming a source of fatigue crack initiation and weakening the fatigue strength of the 3D printed part; a rough surface can also disrupt the continuity of the passivation film, leading to decreased corrosion resistance; and for medical implants, semi-sintered powder is prone to bacterial growth, jeopardizing safety during use.

[0004] Currently, in order to improve the surface quality and reduce the surface roughness of 3D printed parts, the commonly used treatment methods are sandblasting and chemical etching. However, when these two methods are applied to titanium alloy 3D printed parts, there are the following shortcomings: (1) Sandblasting has limited effect on the internal flow path and may introduce residual stress; (2) The uniformity and etching rate of chemical etching are difficult to control, which can easily lead to a reduction in the dimensional accuracy of 3D printed parts, and the effect on improving surfaces with large surface roughness is not ideal, making it difficult to achieve higher surface quality requirements. Summary of the Invention

[0005] In view of the above problems, this application provides a surface treatment method for titanium alloy 3D printed parts, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0006] A first aspect of this application provides a surface treatment method for a titanium alloy 3D printed part, comprising the following steps: sequentially performing a first treatment and chemical polishing on the titanium alloy 3D printed part to obtain a surface-treated printed part; the first treatment includes sequential chemical etching and micro-arc oxidation; the micro-arc oxidation uses an electrolyte comprising the following concentration components:

[0007] Alkali metal hydroxides: 1.5~50 g / L;

[0008] One or more of the following: zincate 0.5~8 g / L, phosphate 0.2~15 g / L, and aluminate 0.5~5 g / L.

[0009] In this embodiment, the first process is performed at least twice.

[0010] In this embodiment, the electrolyte further includes 0.5~3.5 g / L of anionic water-soluble resin.

[0011] In this embodiment, the anionic water-soluble resin includes one or more of anionic water-soluble polyacrylic acid resin, anionic water-soluble polyurethane resin, and anionic water-soluble epoxy resin.

[0012] In this embodiment, the chemical etching uses an etching solution composed of the following weight percentage components: 10%~30% nitric acid, 3%~7% hydrofluoric acid, 0.02%~0.05% p-nitroaniline, and the balance being water.

[0013] In this embodiment, the chemical polishing uses a polishing solution composed of the following components by weight percentage: sulfuric acid 15%~30%, hydrogen peroxide 6%~12%, fluoride 0.5%~5%, with the balance being water.

[0014] In this embodiment, the temperature of the chemical etching is 10~50℃ and the time is 5~30min.

[0015] In this embodiment, the voltage of the micro-arc oxidation is 150~450V and the time is 5~30min.

[0016] In this embodiment, the chemical polishing temperature is 10~45℃ and the time is 5~20min.

[0017] In this embodiment, after the chemical polishing, micro-arc oxidation is further performed using an electrolyte containing alkali metal hydroxide and titanate components.

[0018] The beneficial effects of the embodiments of this application are as follows:

[0019] Compared to traditional sandblasting and chemical etching, the surface treatment method of this application can significantly reduce the surface roughness of titanium alloy 3D printed parts and is also applicable to the surface treatment of internal flow paths. In the prior art, micro-arc oxidation improves the surface properties of the substrate by generating a porous ceramic coating. However, in this process, micro-arc oxidation leads to an increase in the surface roughness of the substrate. This application overcomes the technical bias that micro-arc oxidation will increase the surface roughness of the substrate by using a combination of chemical etching, micro-arc oxidation, and chemical polishing to effectively reduce the surface roughness of titanium alloy 3D printed parts. Specifically:

[0020] (1) In this application, chemical etching, micro-arc oxidation and chemical polishing have a synergistic effect. Chemical etching first can avoid the problem that the high current is difficult to achieve spark discharge during micro-arc oxidation due to the high surface roughness of the titanium alloy 3D printed parts. The subsequent micro-arc oxidation can use its high voltage characteristics to dissolve the metal on the surface of the titanium alloy 3D printed parts, especially the protruding metal, such as the support of the internal flow path, the semi-sintered particles on the surface, etc., and form a loose oxide film. Finally, chemical polishing can dissolve the oxide formed by micro-arc oxidation, thereby achieving surface finishing of the titanium alloy 3D printed parts and reducing the surface roughness of the titanium alloy 3D printed parts.

[0021] (2) The electrolyte used in micro-arc oxidation contains at least one of zincate, phosphate, and aluminate. These components can dissolve in alkaline electrolytes for micro-arc oxidation and can also accumulate on the surface of titanium alloy 3D printed parts during micro-arc oxidation to form a transitional conversion film that is easily dissolved in subsequent acidic chemical polishing solutions. This application achieves pretreatment of rough titanium alloy 3D printed parts by micro-arc oxidation by adjusting the composition of the electrolyte, making it easier to be chemically polished and reducing the surface roughness of titanium alloy 3D printed parts. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a shape drawing of a titanium alloy 3D printed part provided in an embodiment of this application;

[0024] Figure 2 Microscopic morphology of a titanium alloy 3D printed part provided in an embodiment of this application;

[0025] Figure 3 This is a microscopic morphology image of the printed part after surface treatment in Embodiment 1 of this application;

[0026] Figure 4 This is a microscopic morphology image of the printed part after surface treatment, as shown in Comparative Example 4 of this application.

[0027] Figure 5 This is a microscopic morphology image of the printed part after surface treatment, which is Comparative Example 5 of this application. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation of this application should fall within the protection scope of the embodiments of this application.

[0029] It should be understood that, unless the context clearly states otherwise, the terms "comprising," "including," or "having" as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, "comprising" and / or "including" as used herein specify the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof. Some embodiments of this application are described in detail below with reference to the accompanying drawings. Where there is no conflict between the embodiments, the following embodiments and features can be combined with each other. The steps in the following method embodiments are for illustrative purposes only and are not intended to limit this application.

[0030] In this application, the numerical range indicated by "~" refers to the range of values ​​specified as the lower and upper limits, respectively, before or after the term. When multiple values ​​for the upper or lower limit of any numerical range are mentioned, the range disclosed herein can be understood as a range with any one of the mentioned upper limits as its upper limit and any one of the mentioned lower limits as its lower limit.

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the surface treatment method for titanium alloy 3D printed parts will be described below through specific embodiments.

[0032] In one embodiment of this application, a surface treatment method for titanium alloy 3D printed parts is provided, comprising the following steps: sequentially performing a first treatment and chemical polishing on the titanium alloy 3D printed parts to obtain surface-treated printed parts; the first treatment includes sequential chemical etching and micro-arc oxidation; the micro-arc oxidation uses an electrolyte comprising the following concentration components:

[0033] Alkali metal hydroxides: 1.5~50 g / L;

[0034] One or more of the following: zincate 0.5~8 g / L, phosphate 0.2~15 g / L, and aluminate 0.5~5 g / L.

[0035] In this application, the grades of titanium alloy 3D printed parts include, but are not limited to, TC4 alloy, TC11 alloy, TA15 alloy, and pure titanium. Titanium alloy 3D printed parts can be formed using additive manufacturing technologies such as selective laser melting and electron beam melting. The surface treatment method of this application is particularly suitable for titanium alloy 3D printed parts with internal flow channels, where a pump can circulate the liquid agent into the internal flow channels during processing. The structures and applications of the 3D printed parts include, but are not limited to: cooling channels in engine fuel nozzles in the aerospace field; trabecular bone structures and porous structures that promote bone ingrowth in implanted artificial knee joints in the biomedical field; and valve bodies with flow channels in hydraulic systems in the industrial manufacturing field.

[0036] In this application, the alkali metal hydroxide in the micro-arc oxidation electrolyte can be any alkali metal hydroxide or a combination of alkali metal hydroxides, preferably one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide. For example, it can be a combination of sodium hydroxide, potassium hydroxide, lithium hydroxide, a combination of sodium hydroxide and lithium hydroxide, a combination of sodium hydroxide and potassium hydroxide, a combination of potassium hydroxide and lithium hydroxide, or a combination of sodium hydroxide, potassium hydroxide, and lithium hydroxide. The concentration of the alkali metal hydroxide can be 1.5~50 g / L, for example, including but not limited to the following values: 1.5 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, and 50 g / L.

[0037] The zincate can be any zincate or a combination of zincates, preferably one or two of sodium metazincate and sodium tetrahydroxyzincate, for example, it can be a combination of sodium metazincate, sodium tetrahydroxyzincate, sodium metazincate and sodium tetrahydroxyzincate. The concentration of the zincate can be 0.5~8 g / L, for example, including but not limited to the following values: 0.5 g / L, 2 g / L, 4 g / L, 6 g / L, 8 g / L.

[0038] The phosphate can be any phosphate or a combination of phosphates, preferably one or two of sodium phosphate and sodium hexametaphosphate, for example, a combination of sodium phosphate, sodium hexametaphosphate, sodium phosphate, and sodium hexametaphosphate. The concentration of the phosphate can be 0.2 to 15 g / L, for example, including but not limited to the following values: 0.2 g / L, 5 g / L, 10 g / L, and 15 g / L.

[0039] The aluminate can be any aluminate or a composition of aluminates, preferably one or two of sodium tetrahydroxyaluminate and potassium tetrahydroxyaluminate, for example, a composition of sodium tetrahydroxyaluminate, potassium tetrahydroxyaluminate, sodium tetrahydroxyaluminate, and potassium tetrahydroxyaluminate. The concentration of the aluminate can be 0.5~5 g / L, for example, including but not limited to the following values: 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L.

[0040] In this application, the temperature of chemical etching is 10~50℃ and the time is 5~30min, preferably the temperature is 25℃ and the time is 10min; the voltage of micro-arc oxidation is 150~450V and the time is 5~30min, preferably the voltage is 300V and the time is 10min.

[0041] The temperature for chemical polishing is 10~45℃ and the time is 5~20min, preferably 25℃ and 8min.

[0042] In this embodiment, the first process is performed at least twice.

[0043] In this application, for titanium alloy 3D printed parts with high surface roughness (Ra > 20 μm) or deep holes and complex internal flow paths, at least two first treatments consisting of chemical etching and micro-arc oxidation can be performed. The number of treatments can be determined by the surface roughness requirements of the printed part after surface treatment. Specifically, the first chemical etching and micro-arc oxidation primarily remove semi-sintered powder and the largest contour peak. In each subsequent cycle, chemical etching dissolves the loose oxide film generated by the previous micro-arc oxidation, thereby reducing the height difference between the contour peaks and valleys, and ultimately lowering the surface roughness of the titanium alloy 3D printed part to the target level. By performing multiple chemical etching and micro-arc oxidation processes, this application effectively avoids the decrease in dimensional accuracy and surface overheating of titanium alloy 3D printed parts caused by excessively strong single treatments.

[0044] In this embodiment, the electrolyte also includes 0.5~3.5 g / L of anionic water-soluble resin.

[0045] In this application, the anionic water-soluble resin readily precipitates at the micro-protrusions on the surface of the titanium alloy 3D printed part, which serves as the anode, during the micro-arc oxidation process. This increases the surface resistance of the micro-protrusions, making it easier for micro-arc discharge to occur at the micro-recesses. This regulation of micro-arc discharge at the micro-protrusions and recesses can prevent excessive growth of the oxide film at the protrusions and promote more uniform growth of the oxide film, thereby further reducing the surface roughness after chemical polishing. In addition, the anionic water-soluble resin can also improve the wettability of the electrolyte, which ensures that the electrolyte can cover all areas to be treated, including the internal flow path of the titanium alloy 3D printed part, thereby improving the overall surface quality of the titanium alloy 3D printed part. The anionic water-soluble resin can be any anionic water-soluble resin or a composition of anionic water-soluble resins, preferably one or more of anionic water-soluble polyacrylic acid resin, anionic water-soluble polyurethane resin, and anionic water-soluble epoxy resin, more preferably anionic water-soluble polyurethane resin. The concentration of anionic water-soluble resin can be 0.5~3.5 g / L, for example, including but not limited to the following values: 0.5 g / L, 1.0 g / L, 3.5 g / L.

[0046] In this embodiment, the chemical etching uses an etching solution composed of the following components by weight percentage: 10%~30% nitric acid, 3%~7% hydrofluoric acid, 0.02%~0.05% p-nitroaniline, and the balance being water.

[0047] In this application, nitric acid and hydrofluoric acid in the etching solution can synergistically dissolve unmelted powder and printing marks adhering to the surface of the titanium alloy 3D printed parts. p-Nitroaniline, as a corrosion inhibitor, prevents excessive corrosion of the titanium alloy 3D printed parts by the etching solution, reducing surface roughness while ensuring the geometric morphology and dimensional accuracy of the titanium alloy 3D printed parts, especially the internal flow paths. In the etching solution, the weight percentage of nitric acid is expressed as HNO3, and the weight percentage of hydrofluoric acid is expressed as HF.

[0048] In this embodiment, the chemical polishing uses a polishing solution composed of the following components by weight percentage: 15%~30% sulfuric acid, 6%~12% hydrogen peroxide, 0.5%~5% fluoride, and the balance being water.

[0049] In this application, the polishing slurry, through the synergistic effect of sulfuric acid and hydrogen peroxide, can rapidly dissolve the oxide film on the surface after micro-arc oxidation. Fluorides can form stable complexes with titanium ions, promoting further dissolution of the oxide film, thereby reducing the surface roughness of the titanium alloy 3D printed parts, especially the surface roughness of the internal flow paths. In the polishing slurry, the weight percentage of sulfuric acid is calculated as H2SO4, the weight percentage of hydrogen peroxide is calculated as H2O2, and the fluoride is any water-soluble fluoride or a composition of water-soluble fluorides, preferably one or two of sodium fluoride and ammonium fluoride, for example, a composition of sodium fluoride, ammonium fluoride, or sodium fluoride and ammonium fluoride.

[0050] In this embodiment, after chemical polishing, micro-arc oxidation is performed using an electrolyte containing alkali metal hydroxide and titanate. The voltage for micro-arc oxidation is 200-300V, and the time is 5-15 minutes. In the electrolyte, the concentration of alkali metal hydroxide is 1.5-50 g / L, and the concentration of titanate is 0.5-8 g / L. The titanate is any titanate or a combination of titanates, preferably one or two of sodium titanate and potassium titanate, for example, it can be a combination of sodium titanate, potassium titanate, sodium titanate, and potassium titanate.

[0051] In this application, micro-arc oxidation is performed using an electrolyte containing alkali metal hydroxides and titanates after chemical polishing, which can further improve the wear resistance and corrosion resistance of titanium alloy 3D printed parts. This micro-arc oxidation can grow a dense titanium dioxide ceramic layer in situ on the surface of the chemically polished titanium alloy 3D printed parts. Compared with directly forming a coating on the original surface of the titanium alloy 3D printed parts, this titanium dioxide ceramic layer can significantly improve the wear resistance and corrosion resistance of the titanium alloy 3D printed parts.

[0052] The present application will be described in detail below with reference to examples. The embodiments described below according to the present application can be modified in various forms, therefore the scope of the present application should not be construed as limited to the embodiments described in detail below. Examples are provided to help those skilled in the art to more easily understand the present application.

[0053] In the following examples and comparative examples, the titanium alloy 3D printed parts are pure titanium samples, made from pure titanium powder with a diameter of 38~45μm by selective laser melting, and their shapes are as follows. Figure 1 As shown in the figure. The sample has five regions with thicknesses of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm, respectively, and each region contains holes with diameters of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm. The microstructure of the sample is shown in the figure. Figure 2 As shown in the figure, the surface morphology of the sample is irregular and rough.

[0054] Example 1

[0055] A surface treatment method for titanium alloy 3D printed parts includes the following steps: chemical etching, micro-arc oxidation, and chemical polishing are sequentially applied to the titanium alloy 3D printed parts to obtain the surface-treated printed parts, the microstructure of which is shown in the image below. Figure 3 As shown in the figure, the printed parts after surface treatment have a regular shape.

[0056] Chemical etching was performed using an etching solution composed of the following weight percentages: 25% nitric acid (as HNO3), 5% hydrofluoric acid (as HF), 0.05% p-nitroaniline, with the balance being water. The chemical etching temperature was 25°C, and the time was 10 min.

[0057] The micro-arc oxidation uses an electrolyte containing the following components at the following concentrations: sodium hydroxide 12 g / L, sodium zincate 3.5 g / L, sodium phosphate 6 g / L, and sodium tetrahydroxyaluminate 3 g / L. The voltage for micro-arc oxidation is 300 V, and the time is 10 min.

[0058] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 25% sulfuric acid (as H2SO4), 8% hydrogen peroxide (as H2O2), 2.5% sodium fluoride, with the balance being water. The chemical polishing temperature is 20℃ and the time is 8 minutes.

[0059] Example 2

[0060] A surface treatment method for titanium alloy 3D printed parts includes the following steps: sequentially performing a first chemical etching, a first micro-arc oxidation, a second chemical etching, a second micro-arc oxidation, and chemical polishing on the titanium alloy 3D printed parts to obtain the surface-treated printed parts;

[0061] The first and second chemical etchings were both carried out using an etching solution composed of the following weight percentages: 25% nitric acid (as HNO3), 5% hydrofluoric acid (as HF), 0.05% p-nitroaniline, with the balance being water. The temperature for both chemical etchings was 25°C, and the time was 10 min.

[0062] The first and second micro-arc oxidation processes both used an electrolyte containing the following components: sodium hydroxide 12 g / L, sodium zincate 3.5 g / L, sodium phosphate 6 g / L, and sodium tetrahydroxyaluminate 3 g / L. The voltage for both micro-arc oxidation processes was 300 V, and the time was 10 min.

[0063] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 25% sulfuric acid (as H2SO4), 8% hydrogen peroxide (as H2O2), 2.5% ammonium fluoride, with the balance being water. The chemical polishing temperature is 20℃ and the time is 8 minutes.

[0064] Example 3

[0065] The only difference between this embodiment and Embodiment 2 is that in this embodiment, both the first and second micro-arc oxidation processes use an electrolyte containing the following components at the following concentrations: sodium hydroxide 12g / L, sodium zincate 3.5g / L, sodium phosphate 6g / L, sodium tetrahydroxyaluminate 3g / L, and anionic water-soluble polyurethane resin (model WL-312) 3.5g / L.

[0066] Example 4

[0067] The only difference between this embodiment and Embodiment 2 is that in this embodiment, both the first and second micro-arc oxidation processes use an electrolyte containing the following components at the following concentrations: sodium hydroxide 50 g / L, sodium zincate 8 g / L, sodium phosphate 15 g / L, sodium tetrahydroxyaluminate 5 g / L, and anionic water-soluble polyacrylic acid resin (model BASF 678) 2.5 g / L.

[0068] Example 5

[0069] A surface treatment method for titanium alloy 3D printed parts includes the following steps: chemical etching, micro-arc oxidation and chemical polishing are performed on the titanium alloy 3D printed parts in sequence to obtain the surface-treated printed parts;

[0070] Chemical etching uses an etching solution composed of the following weight percentages: 10% nitric acid (as HNO3), 3% hydrofluoric acid (as HF), 0.02% p-nitroaniline, with the balance being water. The temperature for chemical etching is 10°C, and the time is 30 min.

[0071] The micro-arc oxidation uses an electrolyte containing the following components at the following concentrations: sodium hydroxide 1.5 g / L, sodium zincate 0.5 g / L, sodium phosphate 0.2 g / L, and sodium tetrahydroxyaluminate 0.5 g / L. The voltage for micro-arc oxidation is 150 V, and the time is 30 min.

[0072] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 15% sulfuric acid (as H2SO4), 6% hydrogen peroxide (as H2O2), 0.5% sodium fluoride, with the balance being water. The chemical polishing temperature is 10℃ and the time is 20 min.

[0073] Example 6

[0074] A surface treatment method for titanium alloy 3D printed parts includes the following steps: sequentially performing a first chemical etching, a first micro-arc oxidation, a second chemical etching, a second micro-arc oxidation, and chemical polishing on the titanium alloy 3D printed parts to obtain the surface-treated printed parts;

[0075] The first and second chemical etchings were performed using an etching solution composed of the following weight percentages: 30% nitric acid (as HNO3), 7% hydrofluoric acid (as HF), 0.05% p-nitroaniline, with the balance being water. The temperature for both chemical etchings was 50°C, and the time was 5 minutes.

[0076] The first micro-arc oxidation used an electrolyte containing the following components: sodium hydroxide 50 g / L, sodium zincate 8 g / L, and sodium phosphate 15 g / L. The voltage for the first micro-arc oxidation was 450 V, and the time was 5 min.

[0077] The second micro-arc oxidation uses an electrolyte containing the following components: 50 g / L sodium hydroxide and 5 g / L sodium tetrahydroxyaluminate. The voltage for the second micro-arc oxidation is 450 V and the time is 5 min.

[0078] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 30% sulfuric acid (calculated as H2SO4), 12% hydrogen peroxide (calculated as H2O2), 5% ammonium fluoride, with the balance being water. The temperature for chemical polishing is 45℃, and the time is 5 minutes.

[0079] Example 7

[0080] The only difference between this embodiment and Embodiment 6 is that, after chemical polishing, this embodiment also includes micro-arc oxidation (the electrolyte for micro-arc oxidation includes the following components at the following concentrations: sodium hydroxide 22g / L, sodium titanate 6.5g / L), the voltage for micro-arc oxidation is 250V, and the time is 10min.

[0081] Comparative Example 1

[0082] A surface treatment method for titanium alloy 3D printed parts includes the following steps: micro-arc oxidation and chemical polishing are performed on the titanium alloy 3D printed parts in sequence to obtain the surface-treated printed parts;

[0083] The micro-arc oxidation uses an electrolyte containing the following components at the following concentrations: sodium hydroxide 12 g / L, sodium zincate 3.5 g / L, sodium phosphate 6 g / L, and sodium tetrahydroxyaluminate 3 g / L. The voltage for micro-arc oxidation is 300 V, and the time is 10 min.

[0084] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 25% sulfuric acid (as H2SO4), 8% hydrogen peroxide (as H2O2), 2.5% sodium fluoride, with the balance being water. The chemical polishing temperature is 20℃ and the time is 8 minutes.

[0085] Comparative Example 2

[0086] A surface treatment method for titanium alloy 3D printed parts includes the following steps: chemically etching and chemically polishing the titanium alloy 3D printed parts sequentially to obtain the surface-treated printed parts;

[0087] Chemical etching was performed using an etching solution composed of the following weight percentages: 25% nitric acid (as HNO3), 5% hydrofluoric acid (as HF), 0.05% p-nitroaniline, with the balance being water. The chemical etching temperature was 25°C, and the time was 10 min.

[0088] Chemical polishing uses a polishing solution composed of the following components by weight percentage: 25% sulfuric acid (as H2SO4), 8% hydrogen peroxide (as H2O2), 2.5% sodium fluoride, with the balance being water. The chemical polishing temperature is 20℃ and the time is 8 minutes.

[0089] Comparative Example 3

[0090] A surface treatment method for titanium alloy 3D printed parts includes the following steps: chemically etching and micro-arc oxidation are performed on the titanium alloy 3D printed parts in sequence to obtain the surface-treated printed parts;

[0091] Chemical etching was performed using an etching solution composed of the following weight percentages: 25% nitric acid (as HNO3), 5% hydrofluoric acid (as HF), 0.05% p-nitroaniline, with the balance being water. The chemical etching temperature was 25°C, and the time was 10 min.

[0092] The micro-arc oxidation uses an electrolyte containing the following components at the following concentrations: sodium hydroxide 12 g / L, sodium zincate 3.5 g / L, sodium phosphate 6 g / L, and sodium tetrahydroxyaluminate 3 g / L. The voltage for micro-arc oxidation is 300 V, and the time is 10 min.

[0093] Comparative Example 4

[0094] The titanium alloy 3D printed parts were sandblasted. During sandblasting, the steel shot particle size was 0.5mm, the compressed air pressure was 0.4MPa, and the spray distance from the spray gun to the titanium alloy 3D printed parts was 7.5cm.

[0095] Its microscopic morphology diagram is as follows Figure 4 As shown in the figure, the printed part after surface treatment has an irregular shape and cracks appear in some areas.

[0096] Comparative Example 5

[0097] The titanium alloy 3D printed parts were chemically etched. The etching solution consisted of the following components by weight percentage: 60% nitric acid (as HNO3), 10% hydrofluoric acid (as HF), and the balance was water. The etching temperature was 25℃ and the time was 10 min.

[0098] Its microscopic morphology diagram is as follows Figure 5 As shown in the figure, the printed parts after surface treatment have irregular shapes and pits caused by excessive burning.

[0099] Experimental Example 1: Surface Roughness Test

[0100] The surface roughness Ra of the printed parts after surface treatment in Examples 1-6 and Comparative Examples 1-5 was measured using a VK-8700 color 3D laser microscope. The test results are shown in Table 1 below.

[0101] Table 1 Surface roughness test results

[0102]

[0103] The surface roughness of Examples 1-6 is less than that of Comparative Examples 1-5, demonstrating that the surface treatment method in this application can significantly reduce the surface roughness of titanium alloy 3D printed parts. The surface roughness of Examples 3 and 4 is less than that of Example 2, demonstrating that by adding anionic water-soluble resin to the micro-arc oxidation electrolyte, the surface roughness of titanium alloy 3D printed parts can be further reduced.

[0104] Experiment Example 2: Wear Resistance Test

[0105] The friction coefficients of the surface-treated printed parts from Examples 1-7 were tested using a TriboGear friction and wear testing machine. The parameters were set as follows: reciprocating friction test with a TC4 sphere, load 200g, reciprocating stroke 6mm, speed 600mm / s, stroke time 1200s, and no lubrication treatment throughout the test. The test results are shown in Table 2 below.

[0106] Table 2. Friction coefficient test results

[0107]

[0108] As shown in Table 2, the surface treatment method of this application can give titanium alloy 3D printed parts a smaller coefficient of friction and better wear resistance.

[0109] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A surface treatment method for a titanium alloy 3D printed piece, characterized in that, Includes the following steps: The titanium alloy 3D printed part is subjected to a first treatment and chemical polishing in sequence to obtain a surface-treated printed part; the first treatment includes sequential chemical etching and micro-arc oxidation; the micro-arc oxidation uses an electrolyte containing the following concentration components: Alkali metal hydroxides: 1.5~50 g / L; One or more of the following: zincate 0.5~8 g / L, phosphate 0.2~15 g / L, and aluminate 0.5~5 g / L.

2. The surface treatment method for titanium alloy 3D printed parts as described in claim 1, characterized in that, The first process is performed at least twice.

3. The surface treatment method for titanium alloy 3D printed parts as described in claim 1, characterized in that, The electrolyte also includes 0.5~3.5 g / L of anionic water-soluble resin.

4. The surface treatment method for titanium alloy 3D printed parts as described in claim 3, characterized in that, The anionic water-soluble resin includes one or more of anionic water-soluble polyacrylic acid resin, anionic water-soluble polyurethane resin, and anionic water-soluble epoxy resin.

5. The surface treatment method for titanium alloy 3D printed parts as described in any one of claims 1 to 4, characterized in that, The chemical etching process uses an etching solution composed of the following components by weight percentage: 10%~30% nitric acid, 3%~7% hydrofluoric acid, 0.02%~0.05% p-nitroaniline, with the balance being water.

6. The surface treatment method for titanium alloy 3D printed parts as described in any one of claims 1 to 4, characterized in that, The chemical polishing uses a polishing solution composed of the following components by weight percentage: sulfuric acid 15%~30%, hydrogen peroxide 6%~12%, fluoride 0.5%~5%, with the balance being water.

7. The surface treatment method for titanium alloy 3D printed parts as described in any one of claims 1 to 4, characterized in that, The chemical etching is carried out at a temperature of 10~50℃ for a time of 5~30 minutes.

8. The surface treatment method for titanium alloy 3D printed parts as described in any one of claims 1 to 4, characterized in that, The voltage for the micro-arc oxidation is 150~450V, and the time is 5~30min.

9. The surface treatment method for titanium alloy 3D printed parts as described in any one of claims 1 to 4, characterized in that, The chemical polishing temperature is 10~45℃ and the time is 5~20min.

10. The surface treatment method for titanium alloy 3D printed parts according to any one of claims 1 to 4, characterized in that, Following the chemical polishing, the process also includes micro-arc oxidation using an electrolyte containing alkali metal hydroxides and titanates.

Images