GB/T 14952.2-1994 Aluminum and aluminum alloy anodic oxidation anodic oxide film sealing quality assessment acid leaching method GB/T14952.2-1994 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Anodizing of aluminium and its alloys-Assessment of sealing quality by measurement ofthe loss of mass after immersion in acid solutionGB/T 14952.2---94
This standard is equivalent to the international standard ISO2932--1981 "Anodizing of aluminium and its alloys-Assessment of sealing quality by measurement ofthe loss of mass after immersion in acid solution".
Subject content and scope of application
This standard specifies the method for assessing the sealing quality of anodic oxide films of aluminium and aluminium alloys by the mass loss after immersion in acetic acid-sodium acetate or acidified sodium sulfite solution.
This standard is applicable to anodic oxide films that are exposed to the atmosphere, play a protective role in corrosive media and are more resistant to pollution. This standard is not applicable to anodic oxide films treated by the following processes: a. a. Hard anodized film that is usually not sealed; b. Anodized film that is treated with hydrophobicity;
c. Anodized film that is treated only in dichromate solution. This method is a destructive test.
2 Principle of the method
Anodized films that are not sealed will quickly dissolve in a specific acidic medium, while well-sealed films can withstand long-term immersion without obvious corrosion.
Pre-immersion in nitric acid can improve the reproducibility of the results. 3 Reagents
Analytical pure reagents should be used for reagents; distilled water or deionized water should be used for water. 3.1 Nitric acid (1+1).
3.2 Acetic acid-sodium acetate solution (pH2.3-2.5): Dissolve 0.5g of sodium acetate in 100mL of glacial acetic acid solution and dilute to 1000mL with water. Use a new solution after each test. 3.3 Acidified sodium sulfite solution (pH 2.5): Dissolve 10g of anhydrous sodium sulfite in water and dilute to 1000mL. Add glacial acetic acid to make the solution reach pH 3.6-3.8, then add 25% (m/m) sulfuric acid to make the solution pH 2.5 at room temperature. Use new solution after each test. 4 Instruments
Analytical balance sensitivity is 0.1 mg.
Approved by the State Administration of Technical Supervision on March 11, 1994 and implemented on June 1, 1994
5 Preparation of samples
GB/T 14952.2.--- 94
Materials sealed with heat can be sampled at any time after sealing; materials sealed at room temperature should be left for 24 hours before sampling. Cut a sample from the material to be tested, with an effective surface area of ​​about 1dm2 (minimum 0.5dm2). Usually its mass does not exceed 200g. 6 Operation steps
6.1 Measure the total effective surface area S of the sample, excluding the cut edge and other surfaces not covered with oxide film (the surface not covered with oxide film should not exceed 5% of the total surface area of ​​the sample). 6.2 Wipe off the frost on the surface of the sample with a dry cloth (if there are heavy finger marks or grease on the surface of the sample, use an appropriate organic solvent to clean it. For cleaning and drying, refer to A1 and A2 in Appendix A). 6.3 Weigh the sample (m) to the nearest 1mg
6.4 Soak the sample in nitric acid solution (3.1) at 18~22℃ for 10min. Rinse thoroughly with tap water, then rinse in water, refer to A3 in Appendix A for drying, and re-weigh (m2) after complete drying, and weigh to the nearest 0.1mg. 6.5 The sample is treated by the following two methods. 6.5.1 Etching method of acetic acid-sodium acetate solution 6.5.1.1 Soak the specimen in boiling acetic acid-sodium acetate solution (3.2) for 15 minutes. 6.5.1.2 Rinse the specimen in water and dry it according to A3 in Appendix A. After it is completely dried, reweigh it (m:) with an accuracy of 0.1 mg
6.5.1.3 The total effective surface area of ​​several specimens immersed in each liter of solution shall not exceed 3 dm. 6.5.2 Etching method of acidified sodium sulfite solution 6.5.2.1 Soak the specimen in acidified sodium sulfite solution (3.3) for 20 minutes, and keep the temperature at 90~~92℃. Ensure that the solution temperature does not exceed 92℃ and that the sulfur dioxide dissolved in the solution does not precipitate. 6.5.2.2 Rinse the specimen in water and dry it according to A3 in Appendix A. After it is completely dry, re-weigh it (ma) and weigh it to the nearest 0. J mg.
6.5.2.3 The total effective surface area of ​​several specimens immersed in each liter of solution shall not exceed 3 dm7. The result is expressed as
The mass loss per unit area is calculated by the following formula: mz-m:
Am, =
Where: Am. Mass loss per unit area. mg/dm\; m2--mass of the specimen weighed for the first time, mg; m3--mass of the specimen weighed for the third time, mg; S--total effective surface area of ​​the specimen, dm.
The mass loss of nitric acid pre-immersion is obtained by the difference between the first and second weighings. This value is only a reference value. The mass loss of high-quality anodized films in nitric acid pre-immersion is very small (usually less than 10 mg/dm\). The mass loss is significantly higher than 10 mg/dm\, indicating that the anodized film is too soft or porous. bzxz.net
8 Test report
The test report shall include the following contents:
a. Type and identification mark of the inspected product;
This standard number;
GB/T14952.2-94
Test results and the method used (acetic acid-sodium acetate solution or acidified sodium sulfite solution); any differences from the contents specified in this standard (whether agreed or not); test date.
GB/T 14952.2—94
Appendix A
Sample Drying Method Before and After Acid Treatment
(Reference)
A1 At room temperature, slowly stir the sample in an appropriate organic solvent for 30 seconds or scrub and degrease, then place it in an airtight container (pre-drying) for 5 minutes, and then place the sample upright in a drying oven preheated to 60°C and dry it for 15 minutes (when using chlorinated solvents for degreasing, such as perchloroethylene, pre-drying should be carried out in a good fume hood to prevent inhalation of solvent vapor). A2 In a sealed desiccator, place the sample on top of silica gel and cool it for 30 minutes. Repeat the operations of A1 and A2 except that the use of organic solvents is omitted. A3
Additional Notes:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by the Standard and Metrology Institute of China Nonferrous Metals Industry Corporation and the Beijing Nonferrous Metals Research Institute. The main drafters of this standard are Gong Qi, Yao Chuan and Zhu Zufang.
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