GB/T 8013.1-2018Anodic oxide coatings and organic polymer coatings on aluminium and its alloys—Part 1: Anodic oxide coatings (English PDF)

3.1 Dyed anodic coating

Anodic coating colored by adsorption of dyes or pigments in the pore structure.

3.2 Bright anodizing

Anodic oxidation characterized by high specular reflectivity.

3.3 Protective anodizing

Anodic oxidation characterized by corrosion resistance and wear resistance, while appearance is a secondary or unimportant feature.

3.4 Decorative anodic coating

Anodic oxidation characterized by uniform and beautiful appearance.

5.12.2 Accelerated weather resistance

When the purchaser has requirements for xenon lamp accelerated weather resistance and ultraviolet light resistance, the performance requirements shall be indicated in the order form (or contract).

6.1 Appearance

It is performed in accordance with the provisions of GB/T 12967.6.

6.2 Color difference

It is performed in accordance with the provisions of GB/T 12967.6.

6.3 Film thickness

It is performed according to the provisions of GB/T 8014.1. The measurement instructions of average film thickness and local film thickness are shown in Appendix A.

6.4 Surface density

It is performed according to the provisions of the mass loss method in GB/T 8014.2.

6.5 Sealing quality

6.5.1 The test method of sodium molybdate phosphate without nitric acid pre-immersion shall be carried out in accordance with the provisions of Appendix B; the others shall be carried out in accordance with the provisions of the acid etching weight loss method in GB/T 8753.1. GB/T 8753.1 shall be used for arbitration.

6.5.2 The admittance test shall be carried out in accordance with the provisions of GB/T 8753.3.

6.5.3 The dye spot test shall be carried out in accordance with the provisions of GB/T 8753.4.

6.5.4 For the sealing pen test, use a black pen to draw a circle on the specimen; wipe the specimen with a soft cloth dipped in water within 5 s ~ 10 s; visually inspect it.

6.6 Hardness

It is performed according to the provisions of GB/T 9790.

6.7 Wear resistance

6.7.1 Abrasive blasting method

It is performed according to the provisions of GB/T 12967.1.

6.7.2 Sand falling method

It is performed according to the provisions of GB/T 12967.7.

6.7.3 Wheel grinding method

It is performed according to the provisions of GB/T 12967.2.

6.7.4 TABER's wear resistance method

It is performed according to GB/T 12967.1 or the method agreed upon by the supplier and the buyer.

6.7.5 Vibration grinding method

It is performed according to GB/T 12967.1 or the method agreed upon by the supplier and the buyer.

6.7.6 Sandpaper grinding method

It is performed according to GB/T 12967.1 or the method agreed upon by the supplier and the buyer.

6.8 Deformation and crack resistance

It is performed according to the provisions of GB/T 12967.5.

6.9 Environmental corrosion resistance

6.9.1 Salt spray corrosion resistance

NSS test and AASS test shall be carried out in accordance with GB/T 10125; CASS test shall be carried out in accordance with GB/T 12967.3. The rating of corrosion results shall be carried out in accordance with GB/T 6461.

6.9.2 Resistance to sulfur dioxide humid atmosphere corrosion

It is performed in accordance with GB/T 9789. The rating of corrosion results shall be carried out in accordance with GB/T 6461.

6.9.3 Salt solution corrosion resistance

At 23 °C ± 3 °C, immerse the specimen in a salt solution. The composition of the salt solution is shown in Table 9. The test time is 500 h. The rating of corrosion results shall be carried out in accordance with GB/T 6461.

6.10.3 Alcohol resistance

At room temperature, wrap a 500 g wipe head with at least six layers of medical gauze; absorb ethanol (mass fraction 95%); wipe back and forth 100 times on the surface of the specimen, along the same straight line path at a rate of 1 round trip per second (one round trip is counted as 1 time); the wiping stroke is about 100 mm. The gauze shall be kept moist during the test. After the test, visually inspect the surface of the film layer after the test.

6.10.4 Cleaner resistance

At room temperature, immerse the specimen in a 5% neutral detergent solution for 24 hours; take it out and rinse it with tap water; blow dry the specimen; observe the surface of the film.

6.11 Temperature and humidity resistance

6.11.1 Thermal cracking test

Place the specimen in a constant temperature box at 46 °C ± 2 °C; keep it warm for 30 minutes; take out the specimen; visually check whether there are cracks on the surface.

If there are no cracks, increase the temperature by 6 °C and repeat the test until it reaches 82 °C, or a higher temperature agreed upon by the supplier and the buyer.

6.11.2 Thermal aging test

Place the specimen in a constant temperature box at 120 °C ± 3 °C; keep it warm for 30 minutes; take out the specimen; compare the specimen with the original specimen; compare the color change of the specimen with the gray scale card for color change assessment in accordance with GB/T 250. If the color change does not reach level 4, increase the temperature by 20 °C until 200 °C. The heat resistance of the specimen is expressed by the temperature, at which the color change reaches level 4 or exceeds the previous level of level 4.

6.11.3 Low temperature test

Place the specimen in a constant temperature box at -40 °C ± 3 °C; keep warm for 240 h; take out the specimen and let it stand at room temperature for 2 h; observe the surface of the film layer.

6.11.4 High and low temperature cycle test

Perform in accordance with the provisions of 10.11 of GB/T 18911-2002.

6.11.5 Constant temperature and humidity test

6.11.5.1 High humidity method

Place the specimen in a constant temperature and humidity box at 50 °C ± 3 °C and relative humidity of 95% ± 5%; keep warm for 72 h; take out the specimen and let it stand at room temperature for 2 h; observe the surface of the film layer.

6.11.5.2 Medium humidity method

Place the specimen in a constant temperature and humidity chamber at 85 °C ± 3 °C and relative humidity of 85% ± 5% for 1000 hours. After taking out the specimen, let it stand at room temperature for 2 hours and observe the surface of the film.

6.11.5.3 Low humidity method

Place the specimen in a constant temperature and humidity chamber at 80 °C ± 3 °C and relative humidity of 50% ± 5% for 240 hours. After taking out the specimen, let it stand at room temperature for 2 hours and observe the surface of the film.

6.11.6 Temperature and humidity cycle test

Perform according to the provisions of 10.12 in GB/T 18911-2002.

6.12 Weather resistance

6.12.1 Natural weather resistance

Perform according to the provisions of GB/T 11112.

Note: Many countries choose Florida atmospheric corrosion test station for natural weather resistance test. Among the atmospheric corrosion test stations in China, the one with atmospheric conditions closest to Florida is the Qionghai atmospheric corrosion test station in Hainan Province, but the test results of the Qionghai atmospheric corrosion test station in Hainan Province will be different from those of Florida.

6.12.2 Accelerated weather resistance

6.12.2.1 Xenon lamp accelerated weather resistance

Perform according to the provisions of Method 1 Cycle A in GB/T 1865-2009.

6.12.2.2 Ultraviolet light resistance

Perform according to the provisions of GB/T 12967.4.

B.1 Method overview

The specimen is etched by sodium molybdate phosphate solution; the mass loss of the specimen is measured to evaluate the sealing quality of the oxide film.

B.2 Reagents

B.2.1 Unless otherwise specified, the reagents used in this Part are analytically pure; the water used is grade 3 or above distilled water or deionized water specified in GB/T 6682.

B.2.2 Phosphoric acid (rho20 = 1.7 g/mL, H3PO4 content w%. not less than 85.0).

B.2.3 Sodium molybdate (Na2MoO4·2H2O).

B.2.4 Sodium molybdate phosphate solution. Dissolve 1 g of sodium molybdate and 35 mL of phosphoric acid in 500 mL water; transfer to a 1000 mL volumetric flask; dilute to the mark with water; mix well.

B.3 Instruments

B.3.1 Analytical balance, sensitivity 0.1 mg.

B.3.2 Constant temperature water bath, temperature fluctuation not greater than ±1 °C.

B.3.3 Vernier caliper, resolution not greater than 0.05 mm.

B.4 Specimens

B.4.1 For hot-sealed materials, samples can be taken at any time after sealing; for medium-temperature sealed and cold-sealed materials, samples can be taken after standing for more than 24 hours.

B.4.2 Cut the specimen from the material to be tested; the anodized area is about 1 dm² (minimum 0.5 dm²); the specimen weight is usually not more than 200 g.

B.4.3 For hollow extrusions, the specimen shall be cut from the end of the profile with an anodic oxide film on both the inner and outer surfaces of the sample. If the anodic oxide film on the inner surface of the specimen needs to be removed, the anodic oxide film on the inner surface can be removed by mechanical grinding or chemical dissolution, when testing on the outer surface.

B.4.4 After cutting the specimen, the burrs on the cutting edge of the specimen shall be removed.

B.5 Test steps

B.5.1 Measurement of the area of the specimen anodic oxide film

Measure the size of the specimen with a vernier caliper; calculate the area A of the sample anodic oxide film (keep 2 decimal places).

B.5.2 Degreasing

Stir the specimen in an appropriate organic solvent (such as acetone or ethanol) for 30 seconds or scrub to degrease at room temperature. When using chlorinated solvents for degreasing, such as perchloroethylene, pre-drying shall be carried out in a good fume hood to prevent inhalation of solvent vapor.

B.5.3 Drying

First, air dry the specimen at room temperature (pre-drying) for 5 minutes; then place it upright in a drying oven preheated to 60 °C ± 3 °C; dry it for 15 minutes; then place the specimen on top of silica gel in a sealed desiccator to cool for 30 minutes.

B.5.4 Weighing

Weigh the mass of the specimen (m1) immediately to an accuracy of 0.1 mg.

B.5.5 Etching

B.5.5.1 Immerse the specimen upright and completely in the preheated sodium molybdate phosphate solution for 15 minutes, at a test temperature of 38 °C ± 1 °C.

B.5.5.2 Remove the specimen from the test solution; wash it with tap water first, then with deionized water or distilled water. Weigh the mass of the specimen (m2) immediately after drying according to B.5.3, with an accuracy of 0.1 mg.

B.5.5.3 During the operation, do not touch the specimen directly with hands; the drying temperature shall not be higher than 63 °C.

B.5.5.4 The test solution can be reused, but it shall not be used after dissolving more than 4.5 g of material per liter of test solution or treating 10 dm² of oxide film. The solution must not be contaminated by other materials.

B.5.5.5 A water bath and continuous stirring shall be used during the test to ensure uniform solution temperature.

B.6 Result calculation

C.3 Instruments

C.3.1 The test instrument uses a potentiometer, the structure of which is shown in Figure C.1.

C.3.2 The contact surface diameter between the test solution and the specimen is 5 mm.

C.4 Specimen

Specimen size. The test surface width is 75 mm and the length is 150 mm.

C.5 Measurement

C.5.1 Three positions are measured on each specimen; the distance between two positions is not less than 20 mm.

C.5.2 Specimen preparation. Wipe the surface of the specimen film with anhydrous ethanol dipped in a cotton ball; then rinse with pure water; blow dry with a hair dryer; or put the specimen in a drying oven preheated to 60 °C; dry for 15min; cool in a dryer for 20 min.

C.5.3 Specimen loading and heating. Place the dry specimen on a constant temperature test bench; place an insulating pad and a metal electrolytic cell on the surface of the specimen; press and seal it; start heating. At the same time, connect the aluminum alloy substrate and the metal electrolytic cell through a wire. The test temperature is required to be 35 °C ± 1 °C.

C.5.4 Test start. After the temperature reaches the set value and stabilizes for 15 minutes, 3 mL of NaOH solution is injected into the metal electrolytic cell; the time and potential are recorded at the same time.

C.5.5 Test stop. When the potential reaches 1 mV, the test is stopped and the test time is recorded; at the same time, the waste liquid in the electrolytic cell is discharged.

C.5.6 Specimen treatment. Remove the specimen; quickly rinse it with distilled water or deionized water; blow dry the water; dry it for use.

C.5.7 Test device cleaning. Rinse the electrolytic cell with distilled water or deionized water; wipe it dry with filter paper.

C.5.8 Repeat steps C.5.2 ~ C.5.7 to measure other positions.

C.6 Result expression

Take the average value of the measurement results of the five positions as the alkali corrosion resistance breakdown time (min) of the specimen; round it off to one decimal place according to GB/T 8170. […]