Gas steel cylinder inner wall treatment method

Abstract

The invention discloses a gas steel cylinder inner wall treatment method, and belongs to the field of gas steel cylinder inner wall machining. A gas steel cylinder inner wall treatment method comprises the following steps that S1, the inner wall of a steel cylinder is subjected to pretreatment and cleaning before plating; s2, depositing a metal coating on the inner wall of the steel cylinder, and plating the metal coating on the inner wall of the gas steel cylinder through a chemical electroplating method; s3, post-processing the plating layer on the inner wall of the steel cylinder; the method comprises the following steps: washing and cleaning an electroplated layer on the inner wall of the steel cylinder by adopting deionized water; after cleaning is completed, the bottle body is subjected to vacuum drying; s4, after cleaning and airing, the steel cylinder is connected to a vacuum system in a sealed mode, the steel cylinder is placed in a heating furnace to be treated while vacuumizing treatment is conducted on the steel cylinder, and heating densification treatment is conducted on the steel cylinder; according to the method, the flatness of the inner wall of the steel cylinder can be improved, particularly the surface flatness of the cylinder shoulder and the cylinder bottom is improved, the steel cylinder has better corrosion resistance and hydrogen embrittlement resistance, the gas cleanliness is improved, the service life of the steel cylinder is prolonged, and the safety of the steel cylinder is improved.

Description

Technical Field

[0001] The invention belongs to the field of gas cylinder inner wall processing, and more specifically, relates to a gas cylinder inner wall processing method. Background Art

[0002] High-purity specialty gases are widely used in chip manufacturing and wafer manufacturing processes. During storage and transportation, high-quality gas packaging and storage containers are required. Various materials in direct contact with high-purity gases must meet cleanliness standards and be resistant to corrosion and hydrogen embrittlement by various gases. Seamless high-pressure gas cylinders are the most important packaging for high-purity specialty gases, and have very stringent quality requirements for corrosion resistance, inner wall roughness, internal cleanliness, and safety. 6N or 7N electronic specialty gas cylinders used in high-end semiconductors and integrated circuits require inner wall roughness less than 0.15μm, internal moisture content less than 0.1ppm, oil content less than 5mg / m2, and particulate matter content less than 5Pcs / ft3 (0.1μm). my country's cylinder production technology cannot meet the above standards, and high-purity specialty gas cylinders used in the semiconductor industry have long been controlled by Japan's Showa Koatsu. Showa and other companies have a monopoly, with high prices and long delivery cycles, which have seriously affected the supply chain of domestic high-end electronic special gas manufacturers; the main reason for the substandard quality of my country's steel cylinders is the backward technology for treating the inner wall of the steel cylinders. The existing domestic steel cylinder inner wall treatment process is mostly achieved by powder grinding and polishing. The resulting inner wall roughness is relatively high, resulting in a high content of residual moisture, oil and particulate matter adsorbed on the inner wall of the steel cylinder. These residues will contaminate the high-purity special gas; in addition, the traditional powder polishing process does not have enough grinding force on the top shoulder and bottom corners of the steel cylinder, and it is difficult to meet the polishing quality requirements; in addition, there are more than 60 kinds of pure electronic gases and more than 80 kinds of mixed gases required for semiconductor process technology alone. Many gases are corrosive, such as some acidic gases such as H2S. The corrosion process will not only pollute the gas, but also bring safety problems such as hydrogen embrittlement of the bottle body, so the corrosion resistance of the inner wall of the bottle is also very important. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for treating the inner wall of a gas cylinder, which can improve the flatness of the inner wall of the cylinder, especially improve the surface flatness of the bottle shoulder and the bottom of the bottle, so that the cylinder has better corrosion resistance and hydrogen embrittlement resistance, and improve the gas cleanliness and the service life and safety of the cylinder.

[0004] A method for treating the inner wall of a gas cylinder of the present invention comprises the following steps: S1: Pre-treat and clean the inner wall of the cylinder before plating; Abrasive sand is used for grinding. By controlling the movement trajectory and speed of the abrasive sand in the cylinder, the residue with low adhesion and protrusions with poor flatness on the inner wall of the cylinder are ground. After the grinding process is completed, the attachments on the inner wall of the cylinder are cleaned by blasting. S2: After the inner wall of the cylinder is pretreated and cleaned, the electroplating solution is placed in the cylinder, and a consumable metal electrode is installed in the cylinder. The consumable metal electrode and the cylinder are electrically connected to the electroplating power supply, with the consumable metal electrode serving as the anode and the cylinder serving as the cathode. After the electroplating power supply is powered on, the inner wall of the cylinder is electroplated. A metal coating is deposited on the inner wall of the cylinder, and a metal coating is plated onto the inner wall of the gas cylinder by chemical electroplating. After the plating is completed, the electroplating solution is poured out and the consumable metal electrode is removed. S3: Post-processing the coating on the inner wall of the cylinder; first, rinse and clean the electroplated coating on the inner wall of the cylinder using deionized water; after cleaning, vacuum dry the cylinder; S4: After cleaning and drying, the cylinder is sealed and connected to the vacuum system. While the cylinder is being vacuumed, the cylinder is placed in a heating furnace for heating and densification.

[0005] As a further improvement of the present invention, the spray cleaning in step S1 is to use clean high-pressure air equipment to blow away the attachments in the cylinder, and use vacuum equipment to perform dust removal to clean the attachments cleaned from the inside of the cylinder to achieve preliminary surface cleaning.

[0006] As a further improvement of the present invention, in step S2, the thickness of the metal coating is adjusted by controlling the deposition time, electroplating current, electroplating temperature, and electroplating solution concentration.

[0007] As a further improvement of the present invention, the electroplating solution in step S2 includes a solution of the metal to be plated and an additive; the additive is benzenesulfonic acid and sodium lauryl sulfate.

[0008] As a further improvement of the present invention, in step S3, during the flushing and cleaning process, high-pressure pure air is used to assist deionized water in cleaning the residual plating solution of the cylinder coating.

[0009] As a further improvement of the present invention, the vacuum degree of the vacuuming in step S4 is 10Pa-0.00001Pa.

[0010] As a further improvement of the present invention, the heating temperature in step S4 is 100-900 degrees Celsius, and the heating time is 20-120 minutes.

[0011] As a further improvement of the present invention, in step S2, the composition of the metal coating on the inner wall of the cylinder includes one or more of nickel, chromium, silver, copper, titanium, tin, zinc, lead, gold, and silver.

[0012] As a further improvement of the present invention, the metal coating is a single layer or a multilayer coating.

[0013] As a further improvement of the present invention, the inner wall of the steel cylinder is plated with two or more layers; the initial plated layer of the inner wall of the steel cylinder is a copper plated layer; the second plated layer is a nickel plated layer; In step S2 , the metal plating layer is deposited using a cyanide solution to deposit an initial copper plating layer; the thickness of the copper plating layer is 5-15 μm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Through the electroplating deposition process on the inner wall of the cylinder, the inner wall roughness of the cylinder is extremely low, which reduces the adsorption of various impurity particles, moisture and gas on the inner wall of the cylinder, reduces the contamination of the inner wall of the gas cylinder by high-purity gas, meets the requirements of 6N or 7N electronic high-purity special gas, and the coating improves the corrosion resistance and hydrogen embrittlement resistance of the cylinder, and improves the intrinsic safety of the cylinder. (2) The cylinder body is used as the cathode, and the consumable metal electrode inserted into the electrolyte in the cylinder is used as the anode; the coating is obtained by electroplating; the electroplating liquid is placed in the cylinder, so that the cylinder can be filled, so that the shoulder and bottom of the cylinder can be completely covered. During electroplating, the connection between the shoulder and the bottom can be plated with a metal coating, thereby improving the flatness and having better corrosion resistance and hydrogen embrittlement resistance, thereby improving the gas cleanliness and the service life and safety of the cylinder.

[0015] (3) Different from the traditional powder grinding and polishing method of the inner wall of the bottle, the metal plating method can not only reduce the roughness of the inner wall, but also improve the ability of high-pressure seamless steel cylinders to resist hydrogen-induced embrittlement and corrosion to a certain extent; and can select the corresponding electroplating solution for electroplating according to the specific gas characteristics of different gases to obtain different coatings; thereby further improving the service life and safety of the cylinder.

[0016] (4) The metal plating method can adjust the thickness of the coating on the inner wall of the cylinder by controlling technical parameters such as deposition time, current, temperature, and plating solution concentration, so as to meet the needs of different scenarios and different performance requirements, making the application more flexible, thereby further improving the service life and safety of the cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the cross-sectional structure of a typical coating sample of the present invention under a scanning electron microscope; Figure 2 Schematic diagram of the surface structure of a typical coating sample of the present invention under a scanning electron microscope.

[0018] Figure 3 Schematic diagram of a typical gas cylinder structure of the present invention.

[0019] Description of the numbers in the figure: 1. Consumable metal electrode; 2. Electroplating solution; 3. Steel cylinder. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0021] Specific embodiment 1: Please refer to Figure 1-3 A method for treating the inner wall of a gas cylinder, The following steps are involved: Step S1: pre-treating and cleaning the inner wall of the cylinder before plating; Abrasive sand is used for grinding, and the movement trajectory and speed of the abrasive sand in the cylinder 3 are controlled to grind away the residue with low adhesion and the protrusion with poor flatness on the inner wall of the cylinder; After the inner wall of the cylinder is polished and ground, the attachments in the cylinder 3 are blown away by the clean high-pressure air equipment installed externally, and the dust is removed by the vacuum negative pressure equipment installed externally to clean the attachments cleaned from the inside of the cylinder 3 and achieve preliminary surface cleanliness.

[0022] The attached matter is sand and dust, etc.

[0023] Step S2: After the inner wall of the steel cylinder is pretreated and cleaned, a nickel-containing electroplating solution is placed inside the steel cylinder, and a nickel consumable metal electrode is simultaneously installed in the steel cylinder 3. The nickel consumable metal electrode is used as the anode, and the steel cylinder 3 is connected to the cathode of the electroplating power supply. After the electroplating power supply is powered on, the inner wall of the steel cylinder is electroplated. The technical parameters of the electroplating operation are shown in Table 1. A metal coating is deposited on the inner wall of the cylinder by chemical electroplating. After the electroplating is completed, the nickel electroplating solution is poured out and the nickel consumable metal electrode serving as the anode is taken out.

[0024] The thickness and quality of the metal coating on the inner wall of the cylinder are adjusted by controlling technical parameters such as deposition time, electroplating current, electroplating temperature, and electroplating solution concentration. The composition of the nickel electroplating solution and the technical parameters of the operation are shown in Table 1, and a nickel coating with a thickness of 6-12 microns is finally obtained.

[0025] .

[0026] The additives may be benzenesulfonic acid and sodium lauryl sulfate, or other single components or a combination of two or more components.

[0027] Step S3: Clean the electroplating surface of the inner wall of the cylinder with deionized water; rinse and clean the residual plating solution of the cylinder coating with deionized water; use high-pressure pure air to assist the deionized water in cleaning the residual plating solution of the cylinder coating during the rinsing and cleaning process; after cleaning, vacuum dry the bottle body.

[0028] Preferably, the residue on the inner wall of the cylinder is cleaned 3 times with deionized water.

[0029] Step S4: After cleaning and drying, the steel cylinder 3 is sealed and connected to the vacuum system. While the steel cylinder 3 is being vacuumed, the steel cylinder 3 is placed in a heating furnace for heating and densification. During the heat treatment, the steel cylinder 3 is maintained in a high vacuum state, and a high-density nickel plating with a thickness of 6-12 microns is obtained through heat treatment.

[0030] Preferably, the vacuum degree of the vacuuming in step S4 is 10Pa-0.00001Pa.

[0031] Preferably, the heating temperature in step S4 is 100-900 degrees Celsius, and the heating time is 20-120 minutes.

[0032] The nickel coating inside the steel cylinder 3 finally obtained was observed: the coating cross section and surface morphology were observed as follows: Figure 1 and Figure 2 As shown, the coating thickness is about 11 microns, and the coating flatness is higher than the original inner wall flatness of the bottle body.

[0033] The hydrogen sulfide stress corrosion resistance test was carried out on the uncoated samples and the nickel-plated samples with different thicknesses; the test data are shown in Table 2.

[0034]

[0035] From the data in Table 2, it can be clearly seen that the samples with the coating on the inner wall of the cylinder have greatly improved the stress corrosion resistance.

[0036] Specific embodiment 2: Different from specific embodiment 1, in step S2, according to the different gases contained in the cylinder 3, a suitable metal alloy coating is selected according to the gas characteristics corresponding to different gases; for different coatings, corresponding coating anodes, plating solutions and process parameters are selected.

[0037] In step S2, the metal coating on the inner wall of the cylinder may be composed of metals or alloys other than nickel, such as chromium, silver, copper, titanium, tin, zinc, lead, gold, silver and other metal elements or alloys containing the above metal elements.

[0038] The copper plating layer can fill the tiny unevenness on the metal surface, making the surface smoother and flatter, thereby reducing the roughness of the inner wall; and increase the flatness and conductivity of the subsequent plating layer.

[0039] Nickel plating has good ductility and toughness, and can form a uniform and dense coating on surfaces of different shapes and materials, improving corrosion resistance.

[0040] The chrome plating layer has fine crystals and low porosity, which can give the plated surface a good appearance and a low friction coefficient, and improve corrosion resistance.

[0041] In step S3, for different metal coatings, a suitable heat treatment temperature is selected between 200-900° C., and a heat treatment time is selected between 10-120 minutes, which is suitable for the corresponding metal coating.

[0042] The metal coating can be a single layer or a multi-layer coating, and the thickness of each layer can be freely selected according to the needs, with the goal of obtaining the lowest inner wall roughness and the best corrosion resistance.

[0043] Specific embodiment 3: Different from specific embodiment 1 and specific embodiment 2, the inner wall of the cylinder is plated with more than two layers; the initial plated layer of the inner wall of the cylinder is a copper plated layer; the second plated layer is a nickel plated layer; and the third layer is a chromium plated layer; In step S2, the metal plating is deposited using a cyanide solution to deposit an initial copper plating layer. This prevents poor adhesion of the subsequent nickel plating layer, and the copper plating layer also serves to level the inner wall of the cylinder. The copper plating layer has a thickness of 5-15 microns, and the chromium plating layer has better corrosion resistance.

[0044] Specific embodiment 4: Different from specific embodiment 1, specific embodiment 2 and specific embodiment 3, the method for producing the metal coating on the inner wall of the cylinder is not limited to the electrochemical plating method. For example, the metal coating can also be achieved by physical methods.

[0045] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto; any technician familiar with this technical field within the technical scope disclosed in the present application; any equivalent replacement or change based on the technical solution and its improved conception of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for treating the inner wall of a gas cylinder, characterized by: The following steps are involved: S1: Pre-treat and clean the inner wall of the cylinder before plating; Abrasive sand is used for grinding. By controlling the movement trajectory and speed of the abrasive sand in the cylinder, the residue with low adhesion and protrusions with poor flatness on the inner wall of the cylinder are ground. After the grinding process is completed, the attachments on the inner wall of the cylinder are cleaned by blasting. S2: After the inner wall of the cylinder is pretreated and cleaned, the electroplating solution is placed in the cylinder, and a consumable metal electrode is installed in the cylinder simultaneously. The consumable metal electrode and the cylinder are electrically connected to the electroplating power supply, with the consumable metal electrode in the bottle serving as the anode and the cylinder serving as the cathode. After the electroplating power supply is powered on, the inner wall of the cylinder is electroplated; a metal coating is deposited on the inner wall of the cylinder, and the metal coating is plated onto the inner wall of the gas cylinder by chemical electroplating. After the electroplating is completed, the electroplating solution is poured out and the consumable metal electrode is removed. S3: Post-processing the coating on the inner wall of the cylinder; first, rinse and clean the electroplated coating on the inner wall of the cylinder using deionized water; after cleaning, vacuum dry the cylinder; S4: After cleaning and drying, the cylinder is sealed and connected to the vacuum system. While the cylinder is being vacuumed, the cylinder is placed in a heating furnace for heating and densification.

2. A method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The spray cleaning in step S1 is to use clean high-pressure air equipment to blow away the attachments in the cylinder, and use vacuum negative pressure equipment to perform dust removal to clean the attachments cleaned from the inside of the cylinder to achieve preliminary surface cleaning.

3. A method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: In step S2 , the thickness and quality of the metal coating are adjusted by controlling the deposition time, electroplating current, electroplating temperature, and electroplating solution concentration.

4. A method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The electroplating solution in step S2 includes a solution of the metal to be plated and an additive; the additive is benzenesulfonic acid and sodium lauryl sulfate.

5. The method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: In step S3, during the flushing and cleaning process, high-pressure pure air is used to assist deionized water in cleaning the residual plating solution of the cylinder coating.

6. A method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The vacuum degree of the vacuuming in step S4 is 10Pa-0.00001Pa.

7. The method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The heating temperature in step S4 is 100-900 degrees Celsius, and the heating time is 20-120 minutes.

8. The method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: In step S2, the metal coating on the inner wall of the cylinder comprises one or more of nickel, chromium, silver, copper, titanium, tin, zinc, lead, gold, and silver.

9. The method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The metal coating is a single layer or a multi-layer coating.

10. The method for treating the inner wall of a gas cylinder according to claim 1, characterized in that: The inner wall of the cylinder is plated with two or more layers; the initial plating layer of the inner wall of the cylinder is copper plating; the second plating layer is nickel plating; In step S2 , the metal plating layer is deposited using a cyanide solution to deposit an initial copper plating layer; the thickness of the copper plating layer is 5-15 μm.

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