Anodic oxidation method of ZL104 aluminum alloy
By adopting a borosilicate anodizing process and controlling the Al3+ concentration, the film quality problem of ZL104 aluminum alloy parts was solved, achieving a continuous and corrosion-resistant oxide film, eliminating environmental pollution, and meeting the usage requirements of liquid rocket engine parts.
Patent Information
- Application Number
- CN202511003432.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-11-21
AI Technical Summary
The chromic acid anodizing process for ZL104 aluminum alloy parts results in discontinuous film quality, poor corrosion resistance, and easy cracking and peeling. Furthermore, the oxide film on parts from later batches is darker in color and thinner, posing an environmental pollution problem.
Boron-sulfuric acid anodizing was used to replace chromic acid anodizing. The Al3+ concentration in the anodizing solution was controlled to be <20g/L. Chemical degreasing, alkaline washing, descaling and sealing treatments were used to ensure that the film performance met the requirements.
The prepared oxide film is continuous, has good corrosion resistance, does not crack or peel off, has uniform film thickness, eliminates environmental pollution, and meets the requirements for use.
Smart Images
Figure CN120989689A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of anodizing technology, and specifically relates to an anodizing method for ZL104 aluminum alloy. Background Technology
[0002] The surface treatment for aluminum alloy parts used in liquid rocket engines is chromic acid anodizing. However, the chromic acid anodizing process for ZL104 aluminum alloy affects the reliability of the film quality. After anodizing, a discontinuous anodic oxide film is formed, exhibiting poor corrosion resistance, easy cracking and peeling, and a tendency to produce corrosion spots. Furthermore, after continuous anodizing of aluminum alloy parts on the production line, it was found that later batches of aluminum alloy parts had a darker oxide film color and insufficient oxide film thickness. Summary of the Invention
[0003] To overcome the shortcomings of existing technologies, the inventors have conducted intensive research and provided an anodizing method for ZL104 aluminum alloy, which replaces the ZL104 chromic acid anodizing process. This eliminates the quality risks caused by the limited use of the process (forming discontinuous anodized films, poor corrosion resistance, easy cracking and peeling, and easy generation of corrosion black spots), ensuring that the performance of the film prepared by anodizing meets the requirements. At the same time, it also eliminates the problems of dark oxide film color and insufficient oxide film thickness caused by continuous aluminum alloy anodizing.
[0004] The technical solution provided by this invention is as follows:
[0005] An anodizing method for ZL104 aluminum alloy includes the following steps:
[0006] Chemical degreasing of ZL104 aluminum alloy was performed using a chemical degreasing solution.
[0007] ZL104 aluminum alloy was subjected to alkaline washing using an etching solution;
[0008] Ash removal solution was used to remove ash from ZL104 aluminum alloy;
[0009] Anodizing of ZL104 aluminum alloy using anodizing solution;
[0010] The anodic oxide film is sealed using a sealing solution;
[0011] The composition of the anodic oxidation solution is: sulfuric acid 50-60 g / L, boric acid 5-11 g / L, Al 3+ Concentration < 20 g / L, the remainder is water; the anodizing process conditions are: oxidation voltage of 14-16 V, solution temperature of 23-29 °C, and oxidation time of 19-21 min.
[0012] The anodizing method for ZL104 aluminum alloy provided by the present invention has the following beneficial effects:
[0013] (1) The present invention provides an anodizing method for ZL104 aluminum alloy, which uses borosilicate anodizing process to replace chromic acid anodizing process, ensuring that the film prepared by borosilicate anodizing meets the requirements, and at the same time eliminating the environmental pollution caused by CrO3 used in chromic acid anodizing.
[0014] (2) The present invention provides an anodizing method for ZL104 aluminum alloy, which determines the Al content in the anodizing solution. 3+ Al concentration has a significant impact on the quality of the oxide anolyte film. 3+ Excessive concentration affects the color of the oxide film (Al) 3+ Excessive concentration can darken the oxide film and reduce its thickness. This can be addressed by controlling the Al concentration in the anodic oxidation solution. 3+ Concentration <20 g / L, and monitoring of Al in solution during continuous anodizing. 3+ The increased concentration improves the quality of the anodic oxide film, which is beneficial for continuous operation of the anodic oxide production line. Attached Figure Description
[0015] Figure 1 This is a morphology image of the anodic oxide film on the ZL104 aluminum alloy part after anodizing in Example 1;
[0016] Figure 2 This is a morphology diagram of the anodic oxide film on the ZL104 aluminum alloy part after anodizing in Comparative Example 1. Detailed Implementation
[0017] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.
[0018] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.
[0019] This invention provides an anodizing method for ZL104 aluminum alloy, comprising the following steps:
[0020] (1) Chemical degreasing of ZL104 aluminum alloy parts
[0021] When chemically degreasing, the parts are soaked in an alkaline solution. The components of the chemical degreasing solution are: sodium carbonate (Na2CO3, industrial purity) 40-60 g / L, sodium phosphate (Na3PO4, industrial purity) 40-60 g / L, sodium silicate (Na2SiO3·nH2O, industrial purity) 20-30 g / L, and the remainder is water.
[0022] The conditions for the chemical degreasing process are: solution temperature of 50-70℃ and time of 3-15 minutes.
[0023] (2) Etching of ZL104 aluminum alloy parts
[0024] During etching, the parts are immersed in a sodium hydroxide solution. The etching solution consists of 300-500 g / L of sodium hydroxide (NaOH, industrial pure) and the remainder is water.
[0025] The etching process conditions are: the solution temperature is room temperature, and the time is 20-30 seconds.
[0026] (3) Dust removal from ZL104 aluminum alloy parts
[0027] When removing ash, the parts are soaked in nitric acid solution. The composition of the ash removal solution is: nitric acid (HNO3) 300-500g / L, and the remainder is water.
[0028] The conditions for the ash removal process are: the solution temperature is room temperature, and the time is 1 to 5 minutes.
[0029] (4) Anodizing of ZL104 aluminum alloy parts
[0030] The parts undergo an oxidation reaction in a mixed solution of sulfuric acid and boric acid to form an aluminum oxide film. The composition of the anodizing solution is: sulfuric acid (H2SO4) 50-60 g / L, boric acid (H3BO3, chemically pure) 5-11 g / L, Al 3+ Concentration <20g / L, the remainder is water.
[0031] The conditions for the anodizing process are: oxidation voltage of 14-16V, solution temperature of 23-29℃, and oxidation time of 19-21min.
[0032] During the production process, it was discovered that the silicon content of ZL104 aluminum alloy is 8%–10.5%. The chromic acid anodizing process for ZL104 aluminum alloy can affect the reliability of the film quality, such as forming discontinuous anodic oxide films, poor corrosion resistance, easy cracking and peeling, and easy formation of corrosion black spots. Therefore, this invention uses borosilicate anodizing to replace the chromic acid anodizing process, ensuring that the film prepared by borosilicate anodizing meets the performance requirements, while also eliminating the environmental pollution caused by CrO3 used in chromic acid anodizing.
[0033] However, during continuous anodizing of ZL104 aluminum alloy parts on a borosilicate anodizing production line, it was found that later batches of aluminum alloy parts exhibited a darker oxide film color and insufficient oxide film thickness. Extensive research determined that the Al content in the anodizing solution... 3+ Al concentration has a significant impact on the quality of the oxide anolyte film. 3+When the concentration exceeds 20 g / L, a satisfactory anodic oxide film cannot be obtained under the defined process parameters. Therefore, the concentration of Al in the anodic oxide solution needs to be determined. 3+ Concentration <20 g / L, and monitoring of Al in solution during continuous anodizing. 3+ The concentration is adjusted to meet the usage requirements.
[0034] (5) Sealing of ZL104 aluminum alloy parts
[0035] The sealing process involves immersion in a potassium dichromate solution. The sealing solution consists of 5–8 g / L of potassium dichromate (K2Cr2O7, industrial purity) and the remainder is water.
[0036] The sealing process conditions are: solution temperature of 80-100℃ and oxidation time of 20-30 min.
[0037] Between the above adjacent processes, the ZL104 aluminum alloy parts are washed with water to remove the surface treatment liquid and avoid affecting the next process.
[0038] Example
[0039] Example 1
[0040] Step (1) Chemical degreasing of ZL104 aluminum alloy parts
[0041] During chemical degreasing, the parts are immersed in an alkaline solution. The composition and parameters of the chemical degreasing solution are as follows: sodium carbonate (Na2CO3, industrial purity) 45g / L, sodium phosphate (Na3PO4, industrial purity) 43g / L, sodium silicate (Na2SiO3·nH2O, industrial purity) 24g / L, and the remainder is water; the solution temperature is 57℃ and the time is 5min.
[0042] Step (2) Etching of ZL104 aluminum alloy parts
[0043] The parts were immersed in a sodium hydroxide solution during etching. The composition and parameters of the etching solution were: 350 g / L sodium hydroxide (NaOH, industrial pure), and the remainder was water; the solution temperature was room temperature, and the etching time was 23 s.
[0044] Step (3) Desiccation of ZL104 aluminum alloy parts
[0045] The parts were soaked in nitric acid solution during the ash removal process. The composition and parameters of the ash removal solution were: nitric acid (HNO3) 360g / L, the remainder being water; the solution temperature was room temperature, and the time was 2min.
[0046] Step (4) Anodizing of ZL104 aluminum alloy parts
[0047] The parts undergo an oxidation reaction in a mixed solution of sulfuric acid and boric acid to form an aluminum oxide film. The composition and parameters of the anodizing solution are: sulfuric acid (H2SO4) 52 g / L, boric acid (H3BO3, chemically pure) 6 g / L, Al 3+ The concentration was 5 g / L, with the remainder being water; the oxidation voltage was 14 V, the solution temperature was 24 °C, and the oxidation time was 20 min.
[0048] Step (5) Sealing of ZL104 aluminum alloy parts
[0049] The sealing process involved immersion in a potassium dichromate solution. The composition and parameters of the sealing solution were as follows: 8 g / L of potassium dichromate (K2Cr2O7, industrial purity), with the remainder being water; the solution temperature was 85℃, and the oxidation time was 26 min.
[0050] The prepared oxide film was continuous, with a thickness of 3.1–4.2 μm, see [reference needed]. Figure 1 The salt spray test was passed, with no cracking or peeling, and no corrosion spots, meeting the usage requirements.
[0051] Example 2
[0052] Step (1) Chemical degreasing of ZL104 aluminum alloy parts
[0053] During chemical degreasing, the parts are immersed in an alkaline solution. The composition and parameters of the chemical degreasing solution are as follows: sodium carbonate (Na2CO3, industrial purity) 57 g / L, sodium phosphate (Na3PO4, industrial purity) 49 g / L, sodium silicate (Na2SiO3·nH2O, industrial purity) 24 g / L, and the remainder is water; the solution temperature is 56℃ and the time is 7 min.
[0054] Step (2) Etching of ZL104 aluminum alloy parts
[0055] The parts were immersed in a sodium hydroxide solution during etching. The composition and parameters of the etching solution were: sodium hydroxide (NaOH, industrial purity) 460g / L, the remainder being water; the solution temperature was room temperature, and the etching time was 22s.
[0056] Step (3) Desiccation of ZL104 aluminum alloy parts
[0057] The parts were soaked in nitric acid solution during the ash removal process. The composition and parameters of the ash removal solution were: nitric acid (HNO3) 390g / L, the remainder being water; the solution temperature was room temperature, and the time was 4min.
[0058] Step (4) Anodizing of ZL104 aluminum alloy parts
[0059] The parts undergo an oxidation reaction in a mixed solution of sulfuric acid and boric acid to form an aluminum oxide film. The composition and parameters of the anodizing solution are: sulfuric acid (H2SO4) 58 g / L, boric acid (H3BO3, chemically pure) 8 g / L, Al 3+ The concentration was 11 g / L, with the remainder being water; the oxidation voltage was 15 V, the solution temperature was 28 °C, and the oxidation time was 21 min.
[0060] Step (5) Sealing of ZL104 aluminum alloy parts
[0061] The sealing process involved immersion in a potassium dichromate solution. The composition and parameters of the sealing solution were as follows: 6 g / L of potassium dichromate (K2Cr2O7, industrial purity), with the remainder being water; the solution temperature was 87℃, and the oxidation time was 25 min.
[0062] The prepared oxide film is continuous with a thickness of 3.3–4.1 μm. It passed the salt spray test, with no cracking or peeling, and no corrosion spots, thus meeting the usage requirements.
[0063] Example 3
[0064] Step (1) Chemical degreasing of ZL104 aluminum alloy parts
[0065] During chemical degreasing, the parts are immersed in an alkaline solution. The composition and parameters of the chemical degreasing solution are as follows: sodium carbonate (Na2CO3, industrial purity) 56g / L, sodium phosphate (Na3PO4, industrial purity) 45g / L, sodium silicate (Na2SiO3·nH2O, industrial purity) 25g / L, and the remainder is water; the solution temperature is 60℃ and the time is 5min.
[0066] Step (2) Etching of ZL104 aluminum alloy parts
[0067] The parts were immersed in a sodium hydroxide solution during etching. The composition and parameters of the etching solution were: sodium hydroxide (NaOH, industrial pure) 400g / L, the remainder being water; the solution temperature was room temperature, and the etching time was 25s.
[0068] Step (3) Desiccation of ZL104 aluminum alloy parts
[0069] The parts were soaked in nitric acid solution during the ash removal process. The composition and parameters of the ash removal solution were: 450 g / L of nitric acid (HNO3) and the remainder was water; the solution temperature was room temperature and the time was 2 min.
[0070] Step (4) Anodizing of ZL104 aluminum alloy parts
[0071] The parts undergo an oxidation reaction in a mixed solution of sulfuric acid and boric acid to form an aluminum oxide film. The composition and parameters of the anodizing solution are: sulfuric acid (H2SO4) 55 g / L, boric acid (H3BO3, chemically pure) 8 g / L, Al3+ The concentration was 8 g / L, with the remainder being water; the oxidation voltage was 15 V, the solution temperature was 25 °C, and the oxidation time was 20 min.
[0072] Step (5) Sealing of ZL104 aluminum alloy parts
[0073] The sealing process involved immersion in a potassium dichromate solution. The composition and parameters of the sealing solution were as follows: 8 g / L of potassium dichromate (K2Cr2O7, industrial purity), with the remainder being water; the solution temperature was 92℃, and the oxidation time was 25 min.
[0074] The prepared oxide film is continuous with a thickness of 3.0–4.1 μm. It passed the salt spray test, with no cracking or peeling, and no corrosion spots, thus meeting the usage requirements.
[0075] Comparative Example 1
[0076] Comparative Example 1 is identical to Example 1, except that in the anodizing step of the ZL104 aluminum alloy parts, the Al content in the anodizing solution is different. 3+ Concentration > 20 g / L.
[0077] Step (1) Chemical degreasing of ZL104 aluminum alloy parts
[0078] During chemical degreasing, the parts are immersed in an alkaline solution. The composition and parameters of the chemical degreasing solution are as follows: sodium carbonate (Na2CO3, industrial purity) 45g / L, sodium phosphate (Na3PO4, industrial purity) 43g / L, sodium silicate (Na2SiO3·nH2O, industrial purity) 24g / L, and the remainder is water; the solution temperature is 57℃ and the time is 5min.
[0079] Step (2) Etching of ZL104 aluminum alloy parts
[0080] The parts were immersed in a sodium hydroxide solution during etching. The composition and parameters of the etching solution were: 350 g / L sodium hydroxide (NaOH, industrial pure), and the remainder was water; the solution temperature was room temperature, and the etching time was 23 s.
[0081] Step (3) Desiccation of ZL104 aluminum alloy parts
[0082] The parts were soaked in nitric acid solution during the ash removal process. The composition and parameters of the ash removal solution were: nitric acid (HNO3) 360g / L, the remainder being water; the solution temperature was room temperature, and the time was 2min.
[0083] Step (4) Anodizing of ZL104 aluminum alloy parts
[0084] The parts undergo an oxidation reaction in a mixed solution of sulfuric acid and boric acid to form an aluminum oxide film. The composition and parameters of the anodizing solution are: sulfuric acid (H2SO4) 52 g / L, boric acid (H3BO3, chemically pure) 6 g / L, Al 3+ The concentration was 30 g / L, with the remainder being water; the oxidation voltage was 14 V, the solution temperature was 24 °C, and the oxidation time was 20 min.
[0085] Step (5) Sealing of ZL104 aluminum alloy parts
[0086] The sealing process involved immersion in a potassium dichromate solution. The composition and parameters of the sealing solution were as follows: 8 g / L of potassium dichromate (K2Cr2O7, industrial purity), with the remainder being water; the solution temperature was 85℃, and the oxidation time was 26 min.
[0087] The prepared oxide film became darker in color and thinner, with a thickness of 2.4–3.2 μm. (See...) Figure 2 The film layer showed numerous corrosion spots after the salt spray test, indicating that the salt spray test was unsuccessful.
[0088] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
[0089] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. A method for anodizing ZL104 aluminum alloy, characterized in that, Includes the following steps: Chemical degreasing of ZL104 aluminum alloy was performed using a chemical degreasing solution. ZL104 aluminum alloy was subjected to alkaline washing using an etching solution; Ash removal solution was used to remove ash from ZL104 aluminum alloy; Anodizing of ZL104 aluminum alloy using anodizing solution; The anodic oxide film is sealed using a sealing solution; The composition of the anodic oxidation solution is: sulfuric acid 50-60 g / L, boric acid 5-11 g / L, Al 3+ Concentration <20g / L, the remainder is water.
2. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The chemical degreasing solution consists of: sodium carbonate 40-60 g / L, sodium phosphate 40-60 g / L, sodium silicate 20-30 g / L, and the remainder is water.
3. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The conditions for the chemical degreasing process are: solution temperature of 50-70℃ and time of 3-15 minutes.
4. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The etching solution consists of 300-500 g / L sodium hydroxide and the remainder is water.
5. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The etching process conditions are: the solution temperature is room temperature, and the time is 20-30 seconds.
6. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The composition of the ash removal solution is: nitric acid 300-500 g / L, with the remainder being water.
7. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The conditions for the ash removal process are: the solution temperature is room temperature, and the time is 1 to 5 minutes.
8. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The conditions for the anodizing process are as follows: oxidation voltage of 14–16V, solution temperature of 23–29℃, and oxidation time of 19–21min.
9. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The composition of the sealing solution is: 5-8 g / L potassium dichromate, with the remainder being water.
10. The anodizing method for ZL104 aluminum alloy according to claim 1, characterized in that, The sealing process conditions are: solution temperature of 80-100℃ and oxidation time of 20-30 min.
Citation Information
Patent Citations
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