Polishing solution for additive manufacturing high-temperature alloy surface polishing and using method thereof

Abstract

The invention discloses preparation and application methods of an electrolyte plasma polishing solution for additive manufacturing of a high-temperature alloy, and belongs to the technical field of surface treatment. The polishing solution comprises the following components in percentage by weight: 1-4% of sulfate, 1-5% of complexing agent and the balance of deionized water. Wherein the sulfate is selected from one or more of ammonium sulfate, potassium sulfate and sodium sulfate, and the complexing agent is selected from one or more of ethylene diamine tetraacetic acid tetrasodium salt, potassium sodium tartrate, tartaric acid or sodium citrate. The preparation method comprises the following steps: uniformly mixing the components, and heating to 75-85 DEG C. The polishing method comprises the steps that a pretreated high-temperature alloy workpiece is immersed in an electrolyte at the temperature of 75-85 DEG C under the constant voltage condition of 250-350 V to be treated for 5-10 min. According to the technology, the surface roughness can be reduced from Ra6.741 [mu] m to Ra0.942 [mu] m, and the technology has the advantages of being high in polishing efficiency, good in quality and the like. The polishing solution provided by the invention is a neutral or weakly acidic polishing solution, the electrolyte in the polishing solution is environment-friendly and pollution-free, the surface of the polished additive manufacturing high-temperature alloy is bright and glossy, and the polishing solution has a good application prospect in the field of metal additive manufacturing surface post-treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolyte plasma polishing, and in particular relates to a polishing liquid preparation method and a use method thereof for additive manufacturing of high-temperature alloys. Background Art

[0002] Additive manufacturing technology is an advanced manufacturing process that manufactures parts of complex shapes by stacking materials layer by layer. It is widely used in aerospace, automotive, medical and other fields. High-temperature alloys are often used to manufacture high-performance parts due to their excellent high-temperature strength, corrosion resistance and fatigue resistance. However, the surface of additively manufactured high-temperature alloy parts usually has defects such as step effect, spheroidization and microscopic defects, which may affect the corrosion resistance, fatigue life and overall performance of the parts. Surface polishing post-treatment is crucial to improving the quality and reliability of additively manufactured high-temperature alloy parts. It can not only effectively reduce surface roughness, reduce stress concentration points, and improve the fatigue resistance and corrosion resistance of parts, but also extend their service life and ensure reliable operation under extreme conditions. In addition, the improvement of surface quality is of great significance to the widespread application of high-temperature alloy parts in high-end manufacturing industries such as aerospace and automobiles, and is a key link in meeting high-performance requirements.

[0003] Although additive manufacturing technology can quickly manufacture high-temperature alloy parts with complex shapes, its surface quality is often difficult to directly meet the needs of high-performance applications. Although existing polishing methods (such as mechanical polishing, chemical polishing, electrolytic polishing and laser polishing) have certain effects, they have problems such as low efficiency, high cost, environmental pollution or poor adaptability to complex shapes. For example, mechanical polishing is prone to introduce work hardening and surface scratches; chemical polishing and electrolytic polishing have the risk of strong acid and alkali corrosion and environmental pollution; laser polishing equipment is expensive, complicated to operate and has strict requirements on process parameters. These methods are difficult to meet the polishing requirements of complex shapes of additively manufactured high-temperature alloy parts while taking into account efficiency, cost and environmental friendliness.

[0004] Electrolyte plasma polishing technology is an emerging advanced polishing process. Its core principle is to use the gas layer formed between the workpiece and the polishing liquid to remove the microscopic protrusions on the surface of the workpiece through plasma discharge, thereby achieving high-precision and efficient polishing effects. Compared with traditional polishing methods, this technology has significant advantages: its polishing liquid is usually a low-concentration neutral or weakly acidic polishing liquid, and the electrolyte in it is environmentally friendly and pollution-free, and can be recycled by replenishing salt solution. This not only solves the limitations of mechanical polishing in workpiece processing, such as work hardening and surface scratches, but also overcomes the environmental pollution problems faced by chemical polishing and electrochemical polishing. Electrolyte plasma polishing technology is widely used in a variety of application scenarios such as metal surface polishing, deburring, passivation, removal of oxide layers, stains and degreasing. It has the following advantages: high polishing efficiency, high polishing quality, short polishing time, environmental protection and pollution-free, corrosion-resistant and low-stress surface after polishing, and has broad application prospects. However, this technology also faces challenges in the polishing application of metal workpieces of different materials. Different metal materials require different polishing liquids and their process parameter combinations; even for parts of the same material manufactured by different processing methods, using the same polishing liquid and process parameters, there will be some differences in the polishing effect. Taking high-temperature alloys as an example, it is often difficult to achieve ideal results by directly using existing solutions and process parameters suitable for polishing other metal materials. For example, when polishing stainless steel, the use of ammonium sulfate solution can achieve good polishing effects, but when only sulfate or other inorganic salts are used as electrolytes to polish high-temperature alloys, the surface of the workpiece will appear black, severely corroded, and even a large number of molten pits will appear, and it is often difficult to achieve ideal surface quality. Therefore, in view of the particularity of high-temperature alloys, it is necessary to develop a polishing liquid suitable for additive manufacturing of high-temperature alloys. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing and using a polishing liquid for additive manufacturing of high-temperature alloys, so as to overcome the shortcomings of the prior art.

[0006] An electrolyte plasma polishing liquid for high-temperature alloys comprises, by weight percentage, 1% to 4% sulfate, 1% to 5% complexing agent, and the balance is deionized water.

[0007] Preferably, the sulfate is a mixture of one or more of ammonium sulfate, potassium sulfate and sodium sulfate.

[0008] Preferably, the complexing agent is a mixture of one or more of tetrasodium ethylenediaminetetraacetate, potassium sodium tartrate, tartaric acid, and sodium citrate.

[0009] Sulfate is an inorganic salt composed of sulfate ions and metal ions or ammonium ions. Ammonium sulfate and potassium sulfate are both soluble in water and can be used as electrolytes by dissociating ions in water. In the electrolyte plasma polishing process, it is used as the preferred electrolyte for polishing stainless steel and other alloy steels. In the experiment of electrolyte plasma polishing high-temperature alloys, it was found that the use of sulfate as an electrolyte can significantly improve the polishing efficiency and polishing effect. Its effect is to increase the oxidation rate of the workpiece surface during the oxidation stage, thereby improving the overall polishing efficiency. If sulfate is not added, the polishing rate and current efficiency are slow, and the best polishing effect cannot be achieved. If sulfate is replaced with hydrochloride or nitrate, severe corrosion will occur on the surface or edge of the workpiece.

[0010] Complexing agent is an organic compound that can react with metal ions to form a complex and is soluble in water. In the present invention, potassium sodium tartrate and tartaric acid are used as electrolytes. In the experiment, it was found that the use of complexing agent as an electrolyte material can effectively improve the glossiness of the workpiece surface and obtain a lower surface roughness. When only sulfate is used as an electrolyte without adding a complexing agent, a passivation layer is generated on the workpiece surface, and the generated oxide is difficult to remove, the workpiece surface is blackened and serious corrosion occurs. After adding the complexing agent, the compound generated on the workpiece surface is easily removed by plasma bombardment to obtain a smooth surface.

[0011] A method for preparing a high-temperature alloy polishing liquid comprises the following steps:

[0012] (1) 1% to 4% sulfate, 1% to 5% complexing agent, and the balance deionized water are taken by weight percentage;

[0013] (2) Add the weighed sulfate and complexing agent into water and stir thoroughly. After mixing evenly, heat to 75-85° C. to obtain the electrolyte plasma polishing liquid for high-temperature alloys.

[0014] Preferably, the sulfate is a mixture of one or more of ammonium sulfate, potassium sulfate and sodium sulfate.

[0015] Preferably, the complexing agent is a mixture of one or more of potassium sodium tartrate, tartaric acid, tetrasodium ethylenediaminetetraacetate, and sodium citrate.

[0016] A high temperature alloy polishing method comprises the following steps:

[0017] (1) After cleaning the high-temperature alloy workpiece to be polished, clamp it on a special fixture and connect the anode of the power supply to the fixture.

[0018] (2) Add the prepared electrolyte plasma polishing liquid into the polishing tank, stir thoroughly until mixed evenly, heat to 75-85°C, and connect the cathode of the power supply to the electrolyte.

[0019] (3) Connect the DC power supply, constant voltage mode control, output voltage 250V ~ 350V.

[0020] (4) After the output voltage is stabilized, the high-temperature alloy workpiece to be polished is slowly immersed in the polishing liquid for polishing, with an immersion depth of 10 to 50 mm.

[0021] (5) The polishing time is 5 to 10 minutes. During the polishing period, the electrolyte temperature is maintained at 75 to 85°C through a temperature control device.

[0022] (6) After polishing, the workpiece is taken out, cleaned and dried to obtain a polished high-temperature alloy product.

[0023] The technical effects of the present invention are:

[0024] (1) The electrolyte plasma polishing liquid for high-temperature alloys prepared by the present invention has a simple preparation process, safe operation, and will not cause harm to the environment. The surface roughness of the high-temperature alloy after polishing can be reduced from Ra6.741μm to Ra0.942μm within 5 to 10 minutes. The surface of the workpiece after polishing is bright and shiny, and excellent surface quality can be obtained. The polishing time is short, and it is efficient and environmentally friendly. When the electrolyte plasma polishing liquid of other metal materials is used to polish high-temperature alloys, defects such as surface blackening and corrosion will appear on the surface of the workpiece. Other electrolytes with polishing effects will have defects such as low efficiency, severe energy consumption and long polishing time.

[0025] (2) The electrolyte plasma polishing liquid of a high-temperature alloy prepared by the present invention contains sulfate and a chelating agent. The sulfate can increase the oxidation rate of the workpiece surface in the oxidation stage and significantly improve the material removal efficiency. The chelating agent can react with metal ions to form a complex, thereby reducing the concentration of free metal ions. It can reduce the hydrolysis reaction of metal ions and prevent the natural decomposition of the plating solution, thereby enhancing the stability of the electrolyte. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the polishing material in an embodiment of the present invention.

[0027] Figure 2 This is a comparison of the surface morphology of sample No. 5 and the original sample. DETAILED DESCRIPTION

[0028] The present invention is described in detail with reference to the following drawings.

[0029] Examples 1-6

[0030] The components of the electrolyte plasma polishing electrolyte provided in Examples 1-6 are shown in Table 1 below. The solvent used in each example is deionized water, and the percentages shown in the table are all weight percentages in the aqueous solution.

[0031] The specific polishing method comprises the following steps:

[0032] (1) After cleaning the high-temperature alloy workpiece to be polished, clamp it on a special fixture and connect the anode of the power supply to the fixture.

[0033] (2) Add the prepared electrolyte plasma polishing liquid into the polishing tank, stir thoroughly until mixed evenly, heat to 75-85°C, and connect the cathode of the power supply to the electrolyte.

[0034] (3) Connect the DC power supply, constant voltage mode control, output voltage 250V ~ 350V.

[0035] (4) After the output voltage is stabilized, the high-temperature alloy workpiece to be polished is slowly immersed in the polishing liquid for polishing, with an immersion depth of 10 to 50 mm.

[0036] (5) The polishing time is 5 to 10 minutes. During the polishing period, the electrolyte temperature is maintained at 75 to 85°C through a temperature control device.

[0037] (6) After polishing, the workpiece is taken out, cleaned and dried to obtain a polished high-temperature alloy product.

[0038] The polishing part numbers corresponding to each embodiment are detailed in Table 1.

[0039] As shown in the table, the surface conditions of the workpieces after electrolyte plasma polishing using different electrolytes in Examples 1-6 are compared, and the evaluation indicators mainly include: polishing effect and surface roughness.

[0040] like Figure 1 It can be obtained that the polishing effects in Examples 3-5 of the present application are significantly improved, and the additively manufactured GH4169 workpiece polished by the polishing liquid of Example 5 has the best effect. After polishing, the surface of workpiece sample No. 5 obtains good surface gloss and the roughness is significantly reduced.

[0041] Example 1 investigated the polishing situation of using only inorganic salt ammonium sulfate solution without adding complexing agent. The results show that when only sulfate or other inorganic salts are used as electrolyte, the surface of the workpiece will turn black and be accompanied by severe corrosion and even a large number of melting pits. Figure 1 .

[0042] Example 2 investigated the polishing condition of adding complexing agent. The results showed that the surface roughness of the sample decreased when adding complexing agent potassium sodium tartrate, but corrosion still existed. Figure 1 .

[0043] Example 3 investigated the polishing conditions after increasing the concentration of the complexing agent. The results showed that the surface roughness of the workpiece decreased significantly and the surface gloss was good after increasing the concentration of potassium sodium tartrate. Figure 1 .

[0044] Example 4 investigated the polishing conditions after further increasing the concentration of the complexing agent. The results showed that after further increasing the concentration of potassium sodium tartrate, the roughness of the workpiece surface decreased and the surface gloss was good. Figure 1 .

[0045] Example 5 investigated the polishing after adding tartaric acid. The results showed that after adding potassium sodium tartrate and then adding a small amount of tartaric acid, the polishing effect was improved. The roughness of the workpiece surface after polishing decreased and the surface gloss was good. The surface quality was significantly improved compared with the sample before polishing. Figure 1 , Figure 2 .

[0046] Example 6 investigated the polishing conditions after further increasing the sulfate concentration. The results showed that the roughness of the workpiece surface did not decrease significantly after further increasing the sulfate concentration, and corrosion occurred on the surface. Figure 1 .

[0047] By comparing the above phenomena, it can be seen that by adjusting the content of sulfate and chelating agent, the polishing effect of electrolyte plasma polishing additively manufactured high-temperature alloys can be significantly improved, so that the workpiece surface can obtain good gloss and surface roughness.

[0048] It should be noted that the above embodiments are only for describing the preferred embodiments of the present invention and are not intended to limit the present invention. Any modification of the form, equivalent replacement of technical features or partial adjustment of the technical solution made by any person skilled in the art to the embodiments under the premise of following the technical concept of the present invention shall be deemed to fall within the protection scope of the claims of the present invention as long as it does not deviate from the essential content of the present invention.

Claims

1. An electrolyte plasma polishing liquid for additive manufacturing of high-temperature alloys, characterized in that: The composition comprises, by weight percentage, 1% to 4% sulfate, 1% to 5% complexing agent, and the balance is deionized water.

2. The electrolyte plasma polishing electrolyte for additive manufacturing of high-temperature alloys according to claim 1, characterized in that: The sulfate is a mixture of one or more of ammonium sulfate, potassium sulfate and sodium sulfate.

3. The electrolyte plasma polishing electrolyte for additive manufacturing of high-temperature alloys according to claim 1, characterized in that: The complexing agent is a mixture of one or more of tetrasodium ethylenediaminetetraacetate, potassium sodium tartrate, tartaric acid and sodium citrate.

4. A method for preparing a polishing liquid for additive manufacturing of high-temperature alloys, characterized in that: The following steps are involved: (1) 1% to 4% sulfate, 1% to 5% complexing agent, and the balance deionized water are taken by weight percentage; (2) Add the weighed sulfate and complexing agent into water and stir them thoroughly. After mixing evenly, heat them to 75-85° C. to obtain the electrolyte plasma polishing liquid for additive manufacturing of high-temperature alloys.

5. The method for preparing a polishing liquid for additive manufacturing of a high-temperature alloy according to claim 4, characterized in that: The sulfate is a mixture of one or more of ammonium sulfate, potassium sulfate and sodium sulfate.

6. The method for preparing a polishing liquid for additive manufacturing of a high-temperature alloy according to claim 4, characterized in that: The complexing agent is a mixture of one or more of potassium sodium tartrate, tartaric acid, tetrasodium ethylenediaminetetraacetate, and sodium citrate.

7. A method for polishing a high-temperature alloy by additive manufacturing, characterized in that: The following steps are involved: (1) After cleaning the high-temperature alloy workpiece to be polished, clamp it on a special fixture and connect the power anode to the fixture; (2) Add the prepared electrolyte plasma polishing liquid into the polishing tank, stir thoroughly until the mixture is uniform, heat to 75-85° C., and connect the cathode of the power supply to the polishing liquid; (3) Connect the DC power supply, constant voltage mode control, output voltage 250V ~ 350V; (4) After the output voltage is stable, slowly immerse the high-temperature alloy workpiece to be polished into the polishing liquid for polishing, with an immersion depth of 10 to 50 mm; (5) The polishing time is 5 to 10 minutes. During the polishing period, the temperature of the polishing liquid is maintained at 75 to 85°C by a temperature control device; (6) After polishing, the workpiece is taken out, cleaned and dried to obtain a polished additively manufactured high-temperature alloy product.

Images