Method for eliminating carburizing and oxygen permeation layer of high-entropy alloy

Abstract

The invention provides a method for eliminating a carburizing and oxygen permeation layer of a high-entropy alloy, which comprises the following steps: putting the high-entropy alloy without greasy dirt on the surface into a mixed acid solution, reacting for 14-16 minutes until no reddish brown gas and small white bubbles are generated in the mixed acid solution, and finishing the pickling reaction; after the pickling reaction is finished, pouring out a waste mixed acid solution generated by pickling, flushing the high-entropy alloy with water, and immediately putting the high-entropy alloy in water with the water surface higher than the high-entropy alloy material to be subjected to alloy surface deacidification treatment; the mixed acid solution is formed by mixing HF, HNO3 and H2O according to the volume ratio of (6-8): (27-33): (61-65), the volume of the mixed acid solution is 100 parts, the concentration of HF is 40%, the concentration of HNO3 is 65%-68%, and a solvent used by HF and HNO3 is pure water or tap water. According to the method, the carburizing and oxygen permeation layer of the high-entropy alloy can be effectively eliminated, and damage to an alloy body is small.

Description

Technical Field

[0001] The invention belongs to the technical field of eliminating carburized and oxygenated layers of high entropy alloys, and in particular relates to a method for eliminating carburized and oxygenated layers of high entropy alloys. Background Art

[0002] A high entropy alloy is an alloy composed of five or more equal or approximately equal amounts of metallic elements, which is characterized by its high entropy properties and the synergistic effect of multiple elements.

[0003] Carburization and oxygen permeation are product defects in the heat treatment process of high entropy alloy preparation. The reason for carburization and oxygen permeation in high entropy alloy products is that the annealing equipment used is a graphite screen quenching furnace, and this high entropy alloy contains a certain proportion of highly active materials, which causes carburization and oxygen permeation on the surface of the high entropy alloy during the heat treatment process. In addition, the position of the carburized and oxygen permeated layer of the high entropy alloy product is similar to the state of impurity defects, which will affect the mechanical properties of the high entropy alloy and show that it is non-plastic (it can be easily broken when cut into 1mm thin slices). Therefore, in order to recycle and reuse the carburized high entropy alloy material, most of the carburized and oxygen permeated layers must be eliminated; During the heat treatment process, there are generally three methods to prevent carburization: 1) Reserve cutting allowance: The machining allowance value is 1.2 to 1.5 times the depth of the carburized layer. After carburizing, the furnace is cooled, and the part is cut to remove the carburized layer, and then heated and quenched; 2) Copper plating method: Copper plating is performed on the parts that do not need carburizing, with a thickness of 0.035 to 0.055 mm; 3) Paint anti-seepage method: First clean the entire workpiece, and then apply the anti-seepage part to increase the adhesion of the paint. Keep the parts that do not need anti-seepage clean and do not let the paint splash on these surfaces. Generally, the paint (natural or drying) is required to be carburized after drying. However, the above methods 2) and 3) have been heat treated, and the effect of preventing carburization is general. The method of reserving cutting allowance in the first place is still mainly used. However, in the later cutting allowance, a large amount of alloy material waste is caused, so it is urgent to eliminate most of the carburized and oxygenated layers of high entropy alloys and improve their alloy material utilization.

[0004] Pickling is commonly used to treat other alloys for surface carburization or oxygen permeation, such as: Patent publication CN117702119A discloses a metallographic etching solution for a high entropy alloy, a preparation method thereof, and a metallographic etching method. The metallographic etching solution for a high entropy alloy provided by the method comprises: nitric acid, hydrochloric acid, hydrofluoric acid, sulfuric acid, and a solvent, wherein the solvent comprises anhydrous ethanol. The addition of hydrofluoric acid increases the corrosion strength of the etching solution, and can better corrode the high entropy alloy; the addition of sulfuric acid can make the grain boundaries and grains of the corroded high entropy alloy clearer, and the precipitate has a high contrast. However, the introduction of hydrochloric acid and sulfuric acid will cause the alloy body to be corroded to a higher degree, and a new oxide layer will be produced. Specifically, sulfuric acid is the most active binary inorganic strong acid, which will corrode the alloy surface. On the other hand, sulfuric acid has strong oxidizing properties and can oxidize elements on the surface of the high entropy alloy to form an oxide film. In addition, if the pickling reaction time in sulfuric acid is too long, the tensile strength, fracture resistance and other properties of the high entropy alloy will also decrease. Although the corrosion performance of hydrochloric acid is weaker than that of sulfuric acid, it will also affect the alloy body.

[0005] Patent publication KR1020210059548A discloses a low-temperature vacuum carburizing pretreatment solution, wherein the pretreatment solution is nitric acid (HNO 3 ) 30% to 60%, hydrofluoric acid (HF) 20% to 35% and distilled water 20% to 35% are mixed to form a 100% mixed acid by volume, but this solution contains too much nitric acid and is not suitable for high entropy alloys.

[0006] It can be seen that the above method disclosed in the prior art will cause corrosion of the high entropy alloy body after being used on the high entropy alloy, and is therefore not suitable for high entropy alloys. Summary of the invention

[0007] The technical problem to be solved by the present invention is that the existing technology has a poor effect on eliminating the carburized and oxygenated layer of high entropy alloys, and the existing mixed acid solution will cause serious corrosion of the high entropy alloy body after being applied to the high entropy alloy.

[0008] In order to solve the above problems, the present invention provides a method for eliminating the carburized and oxygen-permeated layer of a high entropy alloy, the method comprising: Put the high entropy alloy without oil stain on the surface into the mixed acid solution and react for 14-16 minutes until no red-brown gas and small white bubbles are produced in the mixed acid solution, and the pickling reaction is completed; After the pickling reaction is completed, the waste mixed acid solution produced by pickling is poured out, and the high entropy alloy is rinsed with water and then placed in water with the water surface higher than the high entropy alloy material, waiting for the alloy surface to be deacidified; The mixed acid solution is composed of HF (hydrofluoric acid), HNO 3 (nitric acid), H 2O (water) is mixed in a volume ratio of 6-8:27-33:61-65 to form a mixed acid solution with a volume of 100 parts, the concentration of HF is 40%, and the concentration of HNO 3 The concentration of HF and HNO is 65%~68%. 3 The solvent used is pure water or tap water.

[0009] Preferably, the mixed acid solution is composed of HF (hydrofluoric acid), HNO 3 (nitric acid), H 2 O (water) is mixed in a volume ratio of 7:30:63.

[0010] In order to improve the oil removal effect, preferably, the high entropy alloy with no oil on the surface is treated by placing the high entropy alloy on a roller or placing it in a magnetic polishing to assist in removing part of the oxide scale and treating the surface oil.

[0011] In order to improve the oil removal effect, preferably, the alloy surface deacidification treatment process is: the high entropy alloy is subjected to drum cleaning, ultrasonic water washing, ultrasonic alcohol washing, and drying processes in sequence to treat the surface acid solution.

[0012] Preferably, during the deacidification treatment of the alloy surface, the duration of ultrasonic water washing and ultrasonic alcohol washing is 15 minutes, and the liquid levels of water and alcohol used in the ultrasonic wave are both higher than the alloy surface.

[0013] Preferably, during the deacidification treatment of the alloy surface, the drying treatment temperature is 75° C. to 85° C., and the temperature is kept for 2 to 4 hours, and the alloy is cooled with the furnace and taken out of the furnace.

[0014] Preferably, in the drum cleaning step, 10g to 20g of cleaning agent and detergent, and sufficient tap water or pure water are added, the drum process time is 1 hour, and 20 to 30kg of high entropy alloy can be processed.

[0015] Preferably, after the surface deacidification treatment, a high temperature gas quenching furnace is used to evaporate the residual acid solution. Through this method, the residual solution such as the acid solution, the cleaning agent and the detergent in the gap of the high entropy alloy residual material can be treated.

[0016] The technical effects of the present invention are: The present invention uses HF, HNO 3 , H 2 O mixed acid solution, the purpose is to improve the surface brightness and remove the surface oxide layer and carburized layer. 3 It has a good effect of removing the oxide layer. HF is highly corrosive. Since impurity elements such as carbon and oxygen penetrate into the surface of high entropy alloy under basically the same conditions, (HF+HNO 3) During the treatment of the oxide layer, the effect of carbon potential balance will drive the free carbon in the high-carbon area of ​​the alloy to diffuse to the low-carbon area, causing part of the free carbon (black matter) to precipitate or adhere to the surface of the high-entropy alloy residue. A large amount of black matter is deposited at the bottom of the mixed acid solution. In addition, the black matter attached to the surface of the alloy residue is cleaned in the subsequent drum washing process. At the same time, for the residual solutions such as acid solution, cleaning agent and detergent in the gaps of the high-entropy alloy residue, the residual acid solution can be evaporated by subsequent treatment methods such as high-temperature gas quenching furnace.

[0017] Preferably, 7% HF + 30% HNO 3 +63% H 2 O mixed acid solution, pickling time is 15min, during the reaction, the acid temperature is 38℃~45℃, the reaction is not violent, about 95% of the black matter on the surface of the slice is removed, most of the metallic luster is leaked, and after the subsequent overall composition test, it is found that the carburized and oxygenized slices are in 7% HF+30% HNO 3 +63%H 2 The oxygen and carbon contents in O are both low, and the impurity removal effect is good.

[0018] The present invention performs a roller + ultrasonic + drying process on the pickled alloy residue, which can effectively remove the mixed acid solution remaining on the surface of the alloy residue. The method of the present invention eliminates the carburized and oxygen-permeated layer of the alloy, causes less damage to the alloy body, enhances the utilization effect of the alloy, and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a metallographic diagram of the high entropy alloy carburized layer used in the embodiments and comparative examples before eliminating the carburized and oxygenated layers; Figure 2 The carburized and oxygenated slice after the treatment in Example 1; Figure 3 is a metallographic image of the outer surface of the alloy material after being treated in Example 1; Figure 4 This is a carburized and oxygenated slice after the treatment of Comparative Example 1; Figure 5 This is the carburized and oxygenated slice after the treatment of comparative example 3. DETAILED DESCRIPTION

[0020] The following will be described in detail in conjunction with the embodiments of the technical solution of the present invention. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present invention.

[0021] The invention discloses a method for eliminating a carburized and oxygen-permeated layer of a high entropy alloy, the steps comprising: The high entropy alloy without oil stains on the surface is placed in a mixed acid solution and reacted for 14 to 16 minutes until no red-brown gas and white small bubbles are produced in the mixed acid solution, and the pickling reaction is completed; in this step, the treatment method of the high entropy alloy without oil stains on the surface can be selected as placing the high entropy alloy in a drum to treat the surface oil stains; the mixed acid solution is composed of HF, HNO 3 , H 2 O is mixed in a volume ratio of 6-8:27-33:61-65 to form a mixed acid solution with a volume of 100 parts, the concentration of HF is 40%, and the concentration of HNO 3 The concentration of HF and HNO is 65%~68%. 3 The solvent used is pure water or tap water; after the pickling reaction is completed, the waste mixed acid solution produced by the pickling is poured out, and the high entropy alloy is rinsed with water and then placed in water, and the water surface is higher than the high entropy alloy material, waiting for the alloy surface deacidification treatment; it should be noted that although the HNO used in the following embodiments 3 The concentration is 65%, but under the guidance of the present invention, HNO with a concentration of 66%, 67%, 68% can also be used. 3 .

[0022] The surface deacidification treatment process of the alloy is: the high entropy alloy is sequentially subjected to drum cleaning, ultrasonic water washing, ultrasonic alcohol washing, and drying processes to treat the surface acid solution to prevent the residual material after treatment from being oxidized in the air, resulting in the appearance of color and bluing phenomena; in this step, in the drum cleaning step, a cleaning agent and detergent, an appropriate amount of tap water or pure water are added to treat the high entropy alloy; the ultrasonic water washing and ultrasonic alcohol washing treatment time are both 15 minutes, and the liquid levels of the water and alcohol used in the ultrasonic wave are both above the surface of the alloy; the drying treatment temperature is 75°C~85°C, and the temperature is kept for 2~4 hours, and the furnace is cooled and discharged, and the technicians in this field can select appropriate drying treatment conditions.

[0023] The invention is used for eliminating the carburized and oxygenated layer on the surface of a high entropy alloy material. The method firstly uses a mixed acid to perform a pickling reaction treatment, and then uses a drum + ultrasonic + drying process to treat the mixed acid solution remaining on the surface of the high entropy alloy residue to prevent oxidation.

[0024] The ratio of hydrofluoric acid, nitric acid and water plays a role in the pickling process of the present invention. The percentages in the following embodiments of the mixed acid solution of the present invention all refer to the volume percentage of the solution, and the volume percentages of hydrofluoric acid, nitric acid and pure water add up to 100%. The solvent of the mixed acid and the solvent covering the surface of the residual material can be selected from pure water or tap water, which are stable and can be effectively removed. Before the pickling reaction process, the residual material is properly placed to reduce the contact between the residual material and the bottom of the reaction vessel, thereby increasing the contact area with the mixed acid solution to achieve the effect of sufficient reaction of the residual material.

[0025] According to the implementation mode provided by the present invention, some specific tests have been carried out on the present invention. On this basis, some comparative examples are also given. From these embodiments and comparative examples, it can be seen that the scheme provided by the present invention has achieved better results. It should be noted that the following embodiments are only used to illustrate the present invention in detail and do not limit the protection scope of the invention in any way.

[0026] In the following examples and comparative examples, the carburized and oxygenated layer of the high entropy alloy residue with a weight of 10 kg and a carburized and oxygenated layer of 0.9 mm was removed. The phase diagram of the carburized layer of the alloy is shown in Figure 1 The high entropy alloy composition is a high entropy alloy of Ta:Hf:Ti:Fe:Al with an atomic content ratio of 48%:20%:28%:2%:2%. The atomic content ratio refers to the atomic number ratio.

[0027] Embodiment 1: The specific method of eliminating the carburized and oxygen-permeated layer of high entropy alloy is as follows: Step 1: Put 10kg of high entropy alloy residue into the drum, add about 10ml of cleaning agent and detergent, treat for 1 hour, and rinse the foam on the surface of the residue with water to make the surface free of oil stains; Step 2: Place the high entropy alloy residue without oil stain on the surface into 500 ml of mixed acid solution, and the high entropy alloy residue exceeds the liquid level of the mixed acid solution, and pickle for 15 minutes. After the pickling reaction is completed, rinse with water and then store in water to prevent contact with air. The mixed acid solution is composed of HF:HNO 3 :H 2 O mixed acid prepared in a volume ratio of 7:30:63, HF concentration of 40%, HNO 3 The acid concentration was 65% and the solvent used was pure water. The pickling process was carried out in a room temperature laboratory without deliberately controlling the pickling temperature.

[0028] Step 3: Follow up with the drum process → ultrasonic water washing → ultrasonic alcohol washing → drying process, where the ultrasonic water washing and alcohol washing time are both 15 minutes, and then placed in an 80℃ box-type resistance furnace for drying for 3 hours, and cooled to room temperature with the furnace. After drying, the processed high-entropy alloy residues are selected for qualified residues that are not colored or blackened.

[0029] The high entropy alloy residues after the drum degreasing → pickling process → drum + ultrasonic + drying process were randomly selected from the outer surface of the alloy material for component detection and metallographic analysis. The analysis results showed that the carbon content was 80ppm and the oxygen content was 510ppm. The specific metallographic diagram is shown in Figure 3 .

[0030] Embodiment 2~embodiment 3 The difference between Example 2 and Example 3 and Example 1 is that different mixed acid solutions are used, the pickling reaction time is different, and other control steps are the same as Example 1. The pickling reaction control conditions of Comparative Examples 1 to Comparative Examples 5 are detailed in Table 1.

[0031] Comparative Example 1~Comparative Example 5 The difference between Comparative Examples 1 to 5 and Example 1 is that different mixed acid solutions are used, the pickling reaction time is different, and the other control steps are the same as Example 1. The pickling reaction control conditions of Comparative Examples 1 to 5 are detailed in Table 1.

[0032] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that a different mixed acid solution is used, the pickling reaction time is different, and the other control steps are the same as those of Example 1.

[0033] The mixed acid solution is prepared by hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, and anhydrous ethanol in a volume ratio of 50:8:12:5:25, wherein the concentration of hydrochloric acid is 50%, the concentration of nitric acid is 60%, the concentration of sulfuric acid is 55%, the concentration of hydrofluoric acid is 40%, and the pickling reaction time is 15 minutes.

[0034] Table 1 Acid washing reaction control conditions of various embodiments and comparative examples

[0035] The composition detection and metallographic analysis were performed on the outer surface of the high entropy alloy treated in the embodiment and the comparative example. The analysis results are shown in Table 2.

[0036] Table 2 Detection of alloy surface components and corrosion of the alloy body obtained in each embodiment and comparative example

[0037] It can be seen from the above examples and comparative examples that in Example 1, at 7% HF+30% HNO 3 +63% H 2 O acid solution ratio, the pickling time is 15min. During the reaction process, the acid temperature is between 38℃ and 45℃, the reaction is not violent, and about 95% of the black matter on the surface of the slice is removed, and most of the metallic luster is leaked. After the subsequent overall composition test, it is found that the carburized and oxygen-permeated slices are in 7% HF + 30% HNO 3 +63%H 2 The oxygen and carbon contents in O are both low, that is, the pickling and impurity removal effect is better, such as Figure 2 As shown; In Comparative Example 1, carburized and oxygenated slices were heated to 2.5% HF + 20% HNO 3 +77.5%H 2The reaction in the acid solution is slow, a lot of white bubbles are generated on the surface, and black matter is not cleaned up on the surface of the slice. It is determined that this acid solution ratio is not suitable. Figure 4 As shown; the reason for the poor effect of comparative example 1 is that H 2 When the O content is high, the reaction is slower and takes longer, and a large amount of black matter exists on the alloy surface and is not cleaned up.

[0038] In Comparative Example 3, the carburized and oxygenated slices were heated in 10% HF + 20% HNO 3 +70%H 2 O The reaction is fast in acid solution, a lot of white bubbles are produced on the surface, the temperature rises quickly, and the surface of the slice is particularly rough and acid seepage occurs, such as Figure 3 As shown, it is judged that it is not suitable for treating the carburized and oxygen-permeated high entropy alloy. The comparative example 3 has a poor effect. It is speculated that the reason is that the HF content is high, which is more corrosive to the high entropy alloy, and the acid penetration phenomenon causes pollution, and the reaction is violent and uncontrollable, resulting in a negligent reaction.

[0039] In Comparative Example 4, the carburized and oxygenated slices were heated in 20% HF + 60% HNO 3 +20%H 2 A large amount of red-brown gas is produced during the O reaction, and the reaction is violent and uncontrollable. It is judged that it is not suitable for treating the carburized and oxygen-permeated high-entropy alloy.

[0040] In Comparative Examples 4 and 5, HNO 3 When the content is ≥30%, a large amount of red-brown gas is produced during the reaction. After the pickling reaction, the surface of the alloy becomes colorful and yellow, which in turn increases the oxygen content on the surface of the alloy.

[0041] In Comparative Example 6, after the carburizing and oxygenating slice treatment was completed, the outer surface of the alloy material was tested for composition. The analysis results showed that the carbon content was 270ppm and the oxygen content was 1440ppm, and the reaction was violent and uncontrollable, which seriously corroded the alloy, caused a negligent reaction, and the alloy surface roughness was high, indicating that the mixed acid solution of Comparative Example 6 was not suitable for the high entropy alloy to eliminate the carburizing and oxygenating layer. It is speculated that the reason may be that the content of sulfuric acid, nitric acid, and hydrochloric acid is too high. Sulfuric acid is the most active binary inorganic strong acid, which will corrode the alloy surface. On the other hand, sulfuric acid has strong oxidizing properties and can oxidize the elements on the surface of the high entropy alloy to form an oxide film. Although the corrosion performance of hydrochloric acid is weaker than that of sulfuric acid, it will also affect the alloy body.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for eliminating the carburized and oxygenated layer of a high entropy alloy, characterized in that: The method comprises: Put the high entropy alloy without oil stain on the surface into the mixed acid solution and react for 14-16 minutes until no red-brown gas and small white bubbles are produced in the mixed acid solution, and the pickling reaction is completed; After the pickling reaction is completed, the waste mixed acid solution produced by pickling is poured out, and the high entropy alloy is rinsed with water and then placed in water with the water surface higher than the high entropy alloy material, waiting for the alloy surface to be deacidified; The mixed acid solution is a mixed acid solution with a volume of 100 parts by volume, which is formed by mixing HF, HNO3 and H2O in a volume ratio of 6-8:27-33:61-65, the concentration of HF is 40%, the concentration of HNO3 is 65%-68%, and the solvent used for HF and HNO3 is pure water or tap water.

2. The method for eliminating the carburized and oxygenated layer of high entropy alloy according to claim 1, characterized in that: The mixed acid solution is prepared by mixing HF, HNO3 and H2O in a volume ratio of 7:30:63 to form a mixed acid solution with a volume of 100.

3. The method for eliminating the carburized and oxygenated layer of high entropy alloy according to claim 1, characterized in that: The treatment method of high entropy alloy with no oil stain on the surface is: place the high entropy alloy on a roller or place it in a magnetic polishing to assist in removing part of the oxide scale and treating the surface oil stain.

4. The method for eliminating the carburized and oxygenated layer of high entropy alloy according to claim 1, characterized in that: The alloy surface deacidification treatment process is: the high entropy alloy is subjected to drum cleaning, ultrasonic water washing, ultrasonic alcohol washing, and drying processes in sequence to treat the surface acid solution.

5. The method for eliminating the carburized and oxygenated layer of high entropy alloy according to claim 4, characterized in that: During the deacidification treatment of the alloy surface, the ultrasonic water washing and ultrasonic alcohol washing treatment durations are both 15 minutes, and the liquid levels of the water and alcohol used in the ultrasonic wave are both above the alloy surface.

6. The method for eliminating the carburized and oxygen-permeated layer of high entropy alloy according to claim 1, characterized in that: During the deacidification treatment of the alloy surface, the drying treatment temperature is 75° C. to 85° C., and the temperature is kept for 2 to 4 hours. The alloy is cooled along with the furnace and then taken out of the furnace.

7. The method for eliminating the carburized and oxygenated layer of high entropy alloy according to claim 4, characterized in that: After the surface deacidification treatment, the residual acid solution is evaporated using a high-temperature gas quenching furnace.

Images