A stainless steel oxide layer cleaning liquid and its application

Abstract

The present invention belongs to the field of chemical cleaning technology, and specifically relates to a stainless steel oxide layer cleaning solution and its application. The cleaning solution includes the following components by weight percentage: 10-30% organic acid, 1-3% builder, 0.5-3% dissociation controller, 0.5-4% chelating agent, 0.5-5% inorganic acid, 0.5-3% surfactant, 0.5-3% corrosion inhibitor, and the balance is water. The present invention uses organic acid, builder, dissociation controller, chelating agent, inorganic acid, surfactant, corrosion inhibitor, etc. to degrease, corrode loose, and chelate ablation treatment of the yellow oxide film on the surface of stainless steel. The present invention uses a method of controllable chloride ion hydrolysis to ensure the cleaning efficiency of stainless steel devices and ensure the chloride ion concentration to avoid excessive etching; a stainless steel device with a bright surface is obtained by corroding the yellow oxide coating layer that is difficult to remove on the surface, thereby reducing production costs.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical cleaning, and in particular relates to a stainless steel oxide layer cleaning liquid and application thereof. Background Art

[0002] Stainless steel is often used in the manufacture of various devices in life. Stainless steel is also called stainless acid-resistant steel. Steel that is resistant to weak corrosive media such as air, steam, and water or has stainless properties is called stainless steel; and steel that is resistant to chemical corrosive media is called acid-resistant steel. Due to its special surface element ratio, it is divided into ferritic stainless steel, austenitic stainless steel, austenitic-ferritic duplex stainless steel, etc. according to the different proportions of chromium content. The commonly used stainless steel varieties in industry are 201 type and 304 type stainless steel, which are austenitic stainless steel. During the processing, stainless steel is often subjected to different degrees of stretching, heating and other operations, and a yellow oxide coating that is difficult to remove often appears on the surface. This surface oxidized stainless steel affects the aesthetics of the final device, and the corrosion-resistant nature of the oxide layer affects the practicality of the product. In the mass production process, this type of stainless steel waste appears in large quantities, affecting the yield of the final product. Therefore, it is very necessary to develop a stainless steel cleaning liquid that can effectively remove the yellow oxide on the surface.

[0003] The 201 and 304 stainless steels commonly used in industry are favored for their acid and corrosion resistance. However, in the process of processing this stainless steel, high temperature, bending and other operations are involved, and a layer of oxide film is produced under the influence of various factors. The composition of the oxide film is complex, mainly a mixed oxide of the elements contained in the stainless steel passivation layer. The generation of these oxidized substances reduces the availability and aesthetics of the processed stainless steel devices, affecting the final product quantity.

[0004] At present, there are two commonly used stainless steel cleaning solutions in China:

[0005] 1. Oxidizing strong acid immersion method: This method often uses high-concentration hydrochloric acid, nitric acid, sulfuric acid, and hydrofluoric acid to treat the surface. Because of the high-concentration mixed strong acid, this method is prone to excessive corrosion during the treatment of stainless steel devices, causing the device surface to turn black. In addition, this process requires high operating technology and processing equipment.

[0006] 2. Strong alkali cleaning electroplating method. This method generally uses high concentrations of potassium hydroxide and sodium hydroxide, which are highly alkaline. While removing dirt from the surface of stainless steel, there is a risk of secondary corrosion to the stainless steel if it is not cleaned properly. In addition, the subsequent passivation electroplating operation process is long and the operation is complicated.

[0007] The above cleaning methods not only require a relatively extreme chemical environment, but also use concentrated acid, concentrated alkali or add dangerous substances such as hydrofluoric acid during the cleaning process. These substances are not only harmful to the human body, but also have a bad impact on the environment if the waste liquid is not properly handled. Therefore, an environmentally friendly and easy-to-operate cleaning method is needed.

[0008] In recent years, a new type of stainless steel cleaning method has emerged, which is to use weak acid assisted chloride ion etching method to clean the stainless steel oxide layer. However, this method has the problem that the chloride ion concentration cannot be controlled during the reaction process. Too high chloride ion concentration will cause excessive etching of gaps in the stainless steel, and the stable structure of the metal device cannot be guaranteed. Too low concentration will not produce a good cleaning effect. Summary of the invention

[0009] In order to solve the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a stainless steel oxide layer cleaning liquid, which provides a cleaning liquid with lower industrial equipment and operating technical requirements for the removal of yellow oxide layers on the surfaces of 201 and 304 stainless steels.

[0010] Another object of the present invention is to provide an application of the above-mentioned stainless steel oxide layer cleaning liquid.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] A stainless steel oxide layer cleaning liquid comprises the following components by weight percentage: 10-30% organic acid, 1-3% builder, 0.5-3% dissociation controller, 0.5-4% chelating agent, 0.5-5% inorganic acid, 0.5-3% surfactant, 0.5-3% corrosion inhibitor, and the balance is water.

[0013] Preferably, the organic acid is at least one of citric acid and oxalic acid.

[0014] Preferably, the builder is ammonium chloride.

[0015] Preferably, the dissociation controlling agent is ammonium fluoride.

[0016] Preferably, the chelating agent is at least one of polyacrylic acid, disodium ethylenediaminetetraacetate, hydroxyethylidene diphosphonic acid and aqueous polymaleic anhydride.

[0017] Preferably, the inorganic acid is at least one of nitric acid or hydrochloric acid.

[0018] Preferably, the surfactant is at least one of OP-10, polyvinyl alcohol, and polyoxyethylene ether.

[0019] Preferably, the corrosion inhibitor is at least one of phosphoric acid, rhodium and thiourea.

[0020] Preferably, the stainless steel oxide layer cleaning solution comprises the following components by weight percentage: 10-30% citric acid, 1-3% ammonium chloride, 2-3% ammonium fluoride, 0.5-2% hydroxyethylidene diphosphonic acid, 3% nitric acid, 0.5% polyvinyl alcohol, 1% rhodamine, and the balance is water.

[0021] Preferably, the stainless steel oxide layer cleaning solution comprises the following components by weight percentage: 10-30% oxalic acid, 1.5-2% ammonium chloride, 0.5-1% ammonium fluoride, 0.5-2% hydroxyethylidene diphosphonic acid, 3% nitric acid, 0.5% OP-10, 0.5% thiourea, and the balance is water.

[0022] Preferably, the stainless steel oxide layer cleaning solution comprises the following components by weight percentage: 20-30% oxalic acid, 2.5-3% ammonium chloride, 1-2% ammonium fluoride, 1-3% polyacrylic acid, 2% hydrochloric acid, 2-3% polyoxyethylene ether, 1.5% phosphoric acid, and the balance is water.

[0023] Preferably, the stainless steel oxide layer cleaning solution comprises the following components by weight percentage: 10-20% citric acid, 3% ammonium chloride, 2% ammonium fluoride, 1-3% disodium ethylenediaminetetraacetate, 3% nitric acid, 0.5-2% polyoxyethylene ether, 0.5-1% rhodamine, and the balance is water.

[0024] Preferably, the stainless steel oxide layer cleaning solution comprises the following components by weight percentage: 20-30% citric acid, 1% ammonium chloride, 0.5% ammonium fluoride, 1-3% aqueous polymaleic anhydride, 3% nitric acid, 0.5-2% polyoxyethylene ether, 0.5-1% rhodamine, and the balance is water.

[0025] The application method of the stainless steel oxide layer cleaning liquid comprises: heating the stainless steel oxide layer cleaning liquid to 30-65° C. and placing the stainless steel device to be cleaned therein for cleaning.

[0026] Preferably, during cleaning, one or more of the following methods are used for cleaning:

[0027] (1) After heating the cleaning solution to 40-50°C, put the stainless steel components into the cleaning solution and soak them for 45-55 minutes, then rinse and dry them with hot air;

[0028] (2) After the cleaning solution is heated to 50-60°C, the stainless steel device is placed in the cleaning solution, soaked for 30 minutes, ultrasonically cleaned for 3 minutes, and dried with hot air;

[0029] (3) After the cleaning solution is heated to 60-65°C, the stainless steel device is placed in the cleaning solution, immersed in ultrasound for 10 minutes, and dried with hot air;

[0030] (4) After heating the cleaning solution to 30-60°C, place the stainless steel device in the cleaning solution and soak it for 30 minutes. Use a high-pressure water gun to remove the surface oxide layer.

[0031] In summary, in the above cleaning process, the oxide layer removal on the surface of stainless steel includes the following steps:

[0032] 1. Surface degreasing and dust removal: This step is mainly to remove the dust and industrial grease attached to the stainless steel parts during the processing to avoid affecting the removal efficiency of the stainless steel oxide film. In this step, the surfactant in this product mainly works, such as polyoxyethylene ether, which combines with the surfactant to attach the surface material and remove it.

[0033] 2. Organic acid activation and chelation of surface oxide layer shell: This step mainly loosens the stubborn oxide film structure through the reaction of organic acid with Cr2O3, NiO, FeO, Fe3O4, etc. on the surface film, so that the loose oxide on the surface can be removed during the post-treatment process. At the same time, phosphoric acid solution is added to slow down the reaction rate of organic acid to prevent excessive corrosion.

[0034] 3. Corrosion inhibitors regulate reaction rate: By adding corrosion inhibitors, the excessive reaction of organic acids to the surface sites of the surface oxide layer is prevented, thereby effectively preventing excessive corrosion of stainless steel and affecting the overall surface finish.

[0035] 4. Ultrasonic cleaning process: Use ultrasonic cleaning equipment to remove the loose oxide surface, and then rinse with water to obtain a stainless steel device with a smooth surface.

[0036] 5. Hot air drying process: Place the cleaned stainless steel components in a warm atmosphere to dry the surface moisture and finally obtain a dry and smooth component.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] 1. The stainless steel cleaning agent prepared by the present invention has the advantages of low acidity, chromium-free and environmentally friendly. The present invention abandons the processing steps under extreme conditions such as concentrated acid, concentrated alkali and hydrofluoric acid, and adopts the cleaning conditions of mixing cheap and easily available organic acid with a builder and a low-concentration chloride ion solution, which greatly reduces the requirements for the cleaning environment and also improves the service life of the equipment. At the same time, it reduces the physical harm to the operator and the difficulty of waste liquid treatment; effectively removes the stubborn yellow oxide film on the surface of 201 and 304 stainless steel devices, and obtains stainless steel devices with the same brightness as under extreme conditions.

[0039] 2. The present invention utilizes a method of controlled chloride ion hydrolysis to ensure the cleaning efficiency of stainless steel devices and to ensure chloride ion concentration, thereby avoiding excessive etching; and obtains stainless steel devices with bright surfaces by means of corroding the yellow, difficult-to-remove oxide coating on the surface, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The stainless steel device before and after cleaning according to Application Example 1 is shown in Figure 1. Left: before cleaning; right: after cleaning.

[0041] Figure 2 The following are pictures of a stainless steel device before and after cleaning according to Application Example 2: left: after cleaning; right: before cleaning.

[0042] Figure 3 The following are pictures of a stainless steel device before and after cleaning according to Application Example 3: left: before cleaning; right: after cleaning.

[0043] Figure 4 This is a picture of the stainless steel device after cleaning according to Application Example 4.

[0044] Figure 5 These are pictures of the stainless steel device before and after cleaning according to Application Example 5. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not particularly noted, conventional techniques can be used.

[0046] Example 1 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0047] The preparation method of the stainless steel oxide layer cleaning agent of this embodiment comprises the following steps:

[0048] (1) Weigh the raw materials according to the following mass percentages: 15% citric acid, 1.5% ammonium chloride, 1.5% ammonium fluoride, 3% disodium ethylenediaminetetraacetate, 1% nitric acid, 2% OP-10, 1% rhodamine, 1% phosphoric acid, and the balance is deionized water;

[0049] (2) Dissolve citric acid in deionized water, then add phosphoric acid and stir for 15 minutes, then add disodium ethylenediaminetetraacetate and stir for 5 minutes, and finally add ammonium fluoride, ammonium chloride, nitric acid, OP-10, and rhodamine, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0050] Example 2 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0051] The preparation method of the stainless steel oxide layer cleaning agent of this embodiment comprises the following steps:

[0052] (1) Weigh the raw materials according to the following mass percentages: 30% citric acid, 2% ammonium chloride, 1.5% ammonium fluoride, 1% polyacrylic acid, 1% nitric acid, 1.5% polyoxyethylene ether, 2% rhodamine, and the balance is deionized water;

[0053] (2) Dissolve citric acid in deionized water, then add rhodamine and stir for 10 minutes, then add polyacrylic acid and stir for 5 minutes, finally add ammonium fluoride, ammonium chloride, nitric acid, and polyoxyethylene ether, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0054] Example 3 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0055] The preparation method of the stainless steel oxide layer cleaning agent of this embodiment comprises the following steps:

[0056] (1) Weigh the raw materials according to the following mass percentages: 10% oxalic acid, 3% ammonium chloride, 2.5% ammonium fluoride, 1.5% disodium ethylenediaminetetraacetate, 1% hydroxyethylidene diphosphonic acid, 2.5% nitric acid, 0.5% OP-10, 0.5% polyoxyethylene ether, 1% thiourea, 1% phosphoric acid, and the balance is deionized water;

[0057] (2) Dissolve oxalic acid in deionized water, then add thiourea and phosphoric acid and stir for 15 minutes, then add disodium ethylenediaminetetraacetate and hydroxyethylidene diphosphonic acid and stir for 5 minutes, finally add ammonium fluoride, ammonium chloride, nitric acid, OP-10, and polyoxyethylene ether, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0058] Example 4 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0059] (1) Weigh the raw materials according to the following mass percentages: 15% oxalic acid, 3% ammonium chloride, 1% ammonium fluoride, 2% polyacrylic acid, 1% hydroxyethylidene diphosphonic acid, 0.5% hydrochloric acid, 0.5% OP-10, 0.5% polyvinyl alcohol, 0.5% thiourea, 2% phosphoric acid, and the balance is deionized water;

[0060] (2) Dissolve oxalic acid in deionized water, then add thiourea and phosphoric acid and stir for 15 minutes, then add polyacrylic acid and hydroxyethylidene diphosphonic acid and stir for 5 minutes, finally add ammonium fluoride, ammonium chloride, hydrochloric acid, OP-10, and polyvinyl alcohol, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0061] Example 5 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0062] (1) Weigh the raw materials according to the following mass percentages: 10% oxalic acid, 10% citric acid, 2% rhodamine, 1% phosphoric acid, 1.5% disodium ethylenediaminetetraacetate, 1% hydroxyethylidene diphosphonic acid, 1.5% nitric acid, 3% ammonium chloride, 0.5% polyoxyethylene ether, 0.5% polyvinyl alcohol, and the balance is deionized water;

[0063] (2) Dissolve oxalic acid and citric acid in deionized water, then add thiourea and rhodamine and stir for 15 minutes, then add disodium ethylenediaminetetraacetic acid and hydroxyethylidene diphosphonic acid and stir for 15 minutes, finally add nitric acid, ammonium chloride, polyvinyl alcohol, and polyoxyethylene ether, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0064] Example 6 Preparation of Stainless Steel Oxide Layer Cleaning Agent

[0065] (1) Weigh the raw materials according to the following mass percentages: 30% oxalic acid, 0.7% thiourea, 1.3% phosphoric acid, 1.8% disodium ethylenediaminetetraacetate, 0.1% hydroxyethylidene diphosphonic acid, 5.5% ammonium fluoride, 0.8% nitric acid, 1% ammonium chloride, 2% OP-10, 0.5% polyoxyethylene ether, and the balance is deionized water;

[0066] (2) Dissolve oxalic acid in deionized water, then add thiourea and phosphoric acid and stir for 15 minutes, then add disodium ethylenediaminetetraacetate and hydroxyethylidene diphosphonic acid and stir for 5 minutes, finally add ammonium fluoride, nitric acid, ammonium chloride, OP-10, and polyoxyethylene ether, stir well to evenly disperse the insoluble surfactant, and finally obtain a stainless steel oxide layer cleaning agent.

[0067] Application Example 1

[0068] The stainless steel oxide layer cleaning agent prepared in Example 1 was used to clean the surface oxidized stainless steel components. The specific method was as follows: 1L of stainless steel oxide layer cleaning agent was taken, and the surface oxidized stainless steel was placed in it. The stainless steel was ultrasonically cleaned at 55°C for 15 minutes. The stainless steel components after ultrasonic cleaning were cleaned with water flow and then dried with hot air. The stainless steel components before and after cleaning were as follows: Figure 1 The stainless steel material in the application example is 201 stainless steel. It can be clearly observed that a layer of yellow oxide film is attached to the surface of the stainless steel device before cleaning. After being washed with the cleaning solution, the stainless steel presents a good silvery shiny surface, and the yellow oxide layer on the stainless steel surface is obviously removed.

[0069] Application Example 2

[0070] The stainless steel oxide layer cleaning agent prepared in Example 3 was used to clean the surface oxidized stainless steel components. The specific method was as follows: 100L of the stainless steel oxide layer cleaning agent was taken, and the surface oxidized stainless steel components were placed therein. Ultrasonic cleaning was performed at 60°C for 30 minutes. The stainless steel components after ultrasonic cleaning were cleaned with water flow and then dried with hot air. The stainless steel components before and after cleaning were as follows: Figure 2 The stainless steel material in the application example is 304 stainless steel, and it can be clearly observed that the yellow oxide layer on the stainless steel surface is significantly removed before and after cleaning (the device after cleaning on the left, the device before cleaning on the right).

[0071] Application Example 3

[0072] The stainless steel oxide layer cleaning agent prepared in Example 4 was used to clean the surface oxidized stainless steel components. The specific method was as follows: 50L of stainless steel cleaning agent was taken, and the surface oxidized stainless steel components were placed therein. The stainless steel components were ultrasonically cleaned at 53°C for 20 minutes. The stainless steel components after ultrasonic cleaning were cleaned with water and then dried with hot air. Figure 3 The stainless steel material in the application example is 304 stainless steel, and it can be clearly observed that before and after cleaning (the device before cleaning on the left, the device after cleaning on the right), the yellow oxide layer on the surface of the stainless steel is obviously removed.

[0073] Application Example 4

[0074] Referring to the method of Example 3, the stainless steel oxide layer cleaning agent prepared in Example 5 was used to clean the surface oxidized stainless steel components. Figure 4 As shown in the figure, it can be seen that the stainless steel device is immersed in a cleaning solution containing 3% ammonium chloride. Since the chloride ion concentration cannot be effectively controlled, uneven pitting corrosion of surface oxides occurs on the stainless steel surface. This shows that chloride ions will unevenly clean the surface oxide layer of stainless steel, which will eventually damage the internal structure of the stainless steel device.

[0075] Application Example 5

[0076] Referring to the method of Example 3, the stainless steel oxide layer cleaning agent prepared in Example 6 was used to clean the surface oxidized stainless steel components. Figure 5 As shown in the figure, it can be seen that since the acidity of the overall solution is not enough to clean the oxide layer, although ammonium ions are present as a builder, the overall cleaning effect is not good.

[0077] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A stainless steel oxide layer cleaning liquid, characterized in that: The invention is composed of the following components by weight percentage: 10-30% organic acid, 1-3% builder, 0.5-3% dissociation controller, 0.5-4% chelating agent, 0.5-5% inorganic acid, 0.5-3% surfactant, 0.5-3% corrosion inhibitor, and the balance is water; the builder is ammonium chloride, the dissociation controller is ammonium fluoride; the organic acid is at least one of citric acid and oxalic acid.

2. A stainless steel oxide layer cleaning liquid according to claim 1, characterized in that: The chelating agent is at least one of polyacrylic acid, disodium ethylenediaminetetraacetate, hydroxyethylidene diphosphonic acid and aqueous polymaleic anhydride.

3. A stainless steel oxide layer cleaning liquid according to claim 1, characterized in that: The inorganic acid is at least one of nitric acid and hydrochloric acid.

4. The stainless steel oxide layer cleaning liquid according to claim 1, characterized in that: The surfactant is at least one of OP-10, polyvinyl alcohol and polyoxyethylene ether.

5. The stainless steel oxide layer cleaning liquid according to claim 1, characterized in that: The corrosion inhibitor is at least one of phosphoric acid, rhodium and thiourea.

6. The method for using the stainless steel oxide layer cleaning liquid according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: heating the stainless steel oxide layer cleaning liquid to 30-65° C., placing the stainless steel components to be cleaned therein for cleaning.

7. The method according to claim 6, characterized in that When cleaning, use one or more of the following methods: (1) After heating the stainless steel oxide layer cleaning liquid to 40-50° C., put the stainless steel device into the cleaning liquid, soak it for 45-55 minutes, rinse it, and dry it with hot air; (2) After the stainless steel oxide layer cleaning liquid is heated to 50-60° C., the stainless steel device is placed in the cleaning liquid, soaked for 30 minutes, ultrasonically cleaned for 3 minutes, and dried with hot air; (3) After the stainless steel oxide layer cleaning liquid is heated to 60-65° C., the stainless steel device is placed in the cleaning liquid, immersed in ultrasound for 10 minutes, and dried with hot air; (4) After heating the stainless steel oxide layer cleaning liquid to 30-60° C., put the stainless steel device into the cleaning liquid, soak it for 30 minutes, and use a high-pressure water gun to remove the surface oxide layer.

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