GB/T 12967.3-1991 Copper accelerated acetic acid salt spray test for anodic oxide films of aluminium and aluminium alloys (CASS test) GB/T12967.3-1991 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Anodizing of aluminium and aluminium alloys--Copper accelerated acetic acid salt spray testfor anodic oxide coatings(CASS test)GB/T 12967.3 - 97
This standard is equivalent to the international standard ISO3770--1976 "Copper accelerated acetic acid salt spray test for metal coatings (CASS test)" 1 Subject content and scope of application
This standard specifies the accelerated acetic acid salt spray test method for anodic oxide coatings on aluminum and aluminum alloys. This standard is applicable to the evaluation of the salt spray corrosion resistance of oxide films, and is also applicable to the comparison of the process quality of the same oxide film. Since there are many factors that affect the corrosion of oxide films, this standard is not applicable to the evaluation of the corrosion resistance of the tested oxide film in other environments and the comparison of the corrosion resistance with other oxide films. 2 Reference Standards
GB6461
Rating of Electroplated Samples after Corrosion Test of Metal Covering Layer on Cathodic Substrate 3 Test Solution
3.1 Dissolve analytically pure sodium chloride in distilled water or deionized water to a concentration of 50±5 g/L. 3.2 Add analytically pure copper difluoride (CuC12·2H20) to the sodium chloride solution (3.1.) to a concentration of 0.26±0.02 g/L (or 0205±0.015 g/LCuCl,).
3.3 Adjust the pH value of the solution (3.2) to 3.0~~3.1. The pH value should be measured at 25°C with a pH meter, or tested daily with precision pH test paper. 3.4 The solution must be filtered before use to avoid clogging the nozzle. 4 Test Equipment
4.1 The test equipment should be made of materials resistant to salt spray corrosion. 4.2 The volume of the spray box is not less than 0.2m2, usually greater than 0.4m2. The shape of the top of the box should prevent the droplets condensed on it from falling on the sample. The size and shape of the box should ensure that the amount of liquid collected in the box meets the requirements of Article 7.2. 4.3 The temperature of each arm in the box should meet the requirements of Article 7.1 and maintain a constant temperature. The thermometer and automatic temperature control element should be no less than 100mm away from the inside of the box and can be read from outside the box.
4.4 The spray device consists of a clean air source that can control pressure and humidity, a sprayer, a liquid storage tank and a baffle. Compressed air for spraying: The compressed air for spraying should be pre-filtered to remove oil and impurities, and then humidified by a saturated tower filled with distilled water. The temperature of the saturated tower is 10 to 20°C higher than the humidity in the box. The pressure of the air source should be 70 to 170kPa. Liquid storage tank: There should be a device for constant liquid level. Baffle: used to prevent salt spray from spraying the specimen. Approved by the State Administration of Technical Supervision on June 4, 1991. 458
Implementation on March 1, 1992
GB/T 12967. 3..91
By adjusting the spray pressure, the water temperature in the saturated tower and the position of the baffle, the spray distribution in the box can be uniform, and the salt spray settling speed and the sodium chloride concentration of the collected liquid can reach the requirements of Articles 7 and 2. 4.5 At least two salt spray collectors are placed in the box, one close to the nozzle and one away from the nozzle. The collector consists of a ^i00mm funnel inserted into a graduated container. The collection area of ​​each collector is about 80cm. They are placed in a position to collect only salt spray. 4.6 The test equipment must be cleaned before the test. 5 Specimens
5.1 The type, quantity, shape and size of the specimens shall be determined according to the product standard or the agreement between the two parties. 5.2 The specimens must be cleaned before the test. The cleaning method depends on the degree of contamination on the surface of the sample. The cleaning solvent should not corrode the surface of the sample. After the sample is cleaned, re-contamination should be avoided. 5.3 When cutting the sample, the oxide film near the cutting area must not be damaged. Unless otherwise specified, the cutting area must be protected with paint, paraffin or adhesive tape.
6 Sample placement
6.1 The sample cannot be directly sprayed with salt spray in the test chamber. 6.2 The test surface of the sample faces upward and is at an angle of 15° to 30° to the vertical line, usually 20°. Samples with irregular surfaces should also comply with this regulation as much as possible.
6.3 The samples cannot touch the box or each other. The distance between the samples should ensure that the salt spray falls freely on the test surface of the sample. Droplets on the upper sample or bracket cannot fall on the lower sample. 6.4 The bracket of the sample must be made of non-metallic materials such as glass and plastic. The material for hanging the sample must be made of artificial fiber or other insulating materials.
7 Test conditions
7.1 The temperature of the spray box should be constant at 35±2°C during the test period. 7.2 Salt spray settling rate. After 24 hours of spraying, the solution collected by each collector should be 1~-2mL/80cm·h. The sodium chloride concentration of the collected solution should be 50±10g/L, and the pH value should be 3.1~3.3. 7.3 The spray solution cannot be reused.
7.4 In order to compare the test conditions of different laboratories or different dates, nickel plates can be used for calibration. The calibration method is shown in Appendix A. 8 Test cycle
8.1 The test time should be determined according to the product standard or the agreement between the supply and demand parties. The recommended test time is 4, 8, 16, 21, 32, 40, 48, 5664, 72 h.
8.2 During the specified test period, the spray cannot be interrupted. The salt spray box can be opened for a short time only when observing the sample or when the solution must be replenished in the tank inside the box.
8.3 The sample with the initial corrosion point on the surface needs to be checked frequently, and the sample with the scheduled test cycle cannot be tested together. 8.4 For the test of the scheduled cycle, the box can be opened for inspection according to the test cycle. The test surface must not be damaged during the inspection process. 8.5 After the test, take out the sample and dry it naturally for 0.5 to 1 hour; then gently wash it with clean running water not higher than 40°C. Carefully remove the salt spray solution residue on the surface of the sample, and immediately dry the sample with compressed air or a hair dryer not exceeding 200kPa. Instructions for use:
1) The test time recommended by 1S03770 is 2, 6, 21, 48, 96, 240, 480.720h. +59
9 Evaluation of test results
12967.3-91
In order to meet the needs of different test tools, the test results can be evaluated by a variety of methods, such as quality inspection, microscopic observation, mechanical properties testing, etc. The usual evaluation method is determined by the product label or the requirements of the oxide film being tested. The standard record of general tests should consider the following aspects: a.
Appearance after the test;
Appearance after removing corrosion products;
Time before corrosion begins;
Distribution and quantity of corrosion defects such as pitting, cracks, bubbles, etc. These defects are evaluated according to the relevant provisions of GB6461: Test report
The test report generally includes the following contents:
Stand number of this standard;
Description of the tested sample;
The inclination angle of the sample surface during the test:
Test temperature;
Concentration and pH value of the test solution;
Salt spray settling velocity;
Test cycle;
Evaluation method and results adopted;
The properties of the reference sample placed in the test chamber to check the accuracy of the test conditions and the results obtained. A1 Overview
GB/T12967.3-91
Appendix A
Calibration of test conditions
(reference)
This appendix specifies the method for evaluating the corrosion effect of the spray chamber under given conditions. The results obtained can be compared with the test conditions of different laboratories or the same laboratory at different times. A2 Test specimenbzxZ.net
A2.1 The specimen should be a nickel plate with Ni≥99.0%, C≤0.15%, S≤0.01%, Fe≤0.4%Cu≤0.25%, with a plate thickness of about 1mm and a specimen size of l×b, mm: 100×75.
A2.2 When the specimen is used for the first time, it should be cleaned with a brush dipped in light magnesium oxide slurry, then rinsed in running water, and then immersed in a hydrochloric acid solution (1+4) at a temperature of 21~24℃ for 2min, rinsed with hot water, dried in an oven at 105℃, cooled to room temperature and weighed.
A2.3 After the test, remove the corrosion products to obtain a good surface for the next test. A3 Placement of specimens
In the test chamber, the upward surface of the specimen should face the spray incident direction and be inclined at 30° to the vertical line. The upper edge of the specimen should be on the same horizontal plane as the top of the spray collector. The specimen support should be made of or coated with an inert material. A4 Determination of weight loss
A4.1 After 24 hours of testing, rinse the sample with cold water to remove the residual salt spray, then soak it in a hydrochloric acid solution (1+4) at a temperature of 21-24°C for 2 minutes to remove the corrosion products, then rinse it in water, dry it in an oven at 105°C, cool it to room temperature, and weigh it. A4.2 After 24 hours of spraying, the mass loss of each sample placed at the four corners of the box should be 35-70 mg. Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Southwest Aluminum Processing Plant. The main drafters of this standard are Shi Yufen and Chen Shaokang. 461
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