GB/T 8753.2-2005Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 2: Phosphoric acid/chromic acid test (English PDF)
铝及铝合金阳极氧化 氧化膜封孔质量的评定方法 第2部分：-硝酸预浸的磷铬酸法
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Issued by
General Administration of Quality Supervision, Inspection and Quarantine of PRC
Level / Type
National · Recommended
Issue date
July 4, 2005
Implementation date
December 1, 2005
Scope
GB/T 8753.2-2005 is the English-translated version of 铝及铝合金阳极氧化 氧化膜封孔质量的评定方法 第2部分：-硝酸预浸的磷铬酸法.
GB/T 8753.2-2005 — This part specifies the method for assessing the quality of sealed anodic oxidation coatings of aluminum and aluminum alloy, after nitric acid predip AND etching in phosphoric acid / chromic acid solution, through the loss of mass.
This part applies to both hot-sealed anodic oxidation coating and cold-sealed anodic oxidation coating.
This part does not apply to the anodic oxidation coating, which was treated by the following processes. a) Hard anodic oxidation coating that is usually not sealed; b) Anodic oxidation coating that has been sealed in a dichromate solution; c) Anodic oxidation coating produced in chromic acid solution; d) Anodic oxidation coating after hydrophobic treatment.
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Document preview — GB/T 8753.2-2005
National Standard of the People's Republic of China
- ICS
- 25.220.20
- Classification
- H 21
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of PRC
Contents
- Foreword...3
- 1 Scope...5
- 2 Principle of method...5
- 3 Reagents...5
- 4 Instruments...6
- 5 Specimens...6
- 6 Test procedure...6
- 7 Presentation of results...7
- 8 Test report...7
Foreword
GB/T 8753 "Anodizing of aluminum and its alloys - Assessment of quality of
sealed anodic oxidation coatings" is divided into 4 parts.
- GB/T 8753.1-2005 Anodizing of aluminum and its alloys - Assessment of
quality of sealed anodic oxidation coatings - Part 1.Measurement of the
loss of mass after immersion in acid solution(s);
- GB/T 8753.2-2005 Anodizing of aluminum and its alloys - Assessment of
quality of sealed anodic oxidation coatings - Part 2.Phosphoric
acid/chromic acid test with nitric acid predip;
- GB/T 8753.3-2005 Anodizing of aluminum and its alloys - Assessment of
quality of sealed anodic oxidation coatings - Part 3.Admittance method;
- GB/T 8753.4-2005 Anodizing of aluminum and its alloys - Assessment of
quality of sealed anodic oxidation coatings - Part 4.Dye spot test with prior
acid treatment.
This part is Part 2 of GB/T 8753.
This part is non-equivalent to EN 12373-7.1999 "Aluminum and aluminum
alloys - Anodizing - Assessment of quality of sealed anodic oxidation coatings
by measurement of the loss of mass after immersion in phosphoric acid/chromic
acid solution with prior acid treatment" (English version). Compared with EN
12373-7.1999, the main content changes are as follows.
- In Chapter 5, ADD that "For cold-sealed materials, they shall be placed for
more than 24 hours before sampling."
From the date of implementation of this part, GB/T 14952.2-1994 "Anodizing of
aluminum and its alloys - Assessment of sealing quality by measurement of the
loss of mass after immersion in acid solution" shall be abolished at the same
time.
Because the "acid dipping method" is not as correlated, to actual use, as the
"phosphoric acid / chromic acid method with nitric acid predip", the "acid dipping
method" is rarely used at home and abroad. European countries have also
abolished their corresponding standards. Therefore, this part specifies the
"phosphoric acid / chromic acid method with nitric acid predip"; meanwhile it
abolishes the "acid dipping method".
The phosphoric acid / chromic acid test with nitric acid predip is a destructive
test.
This part is especially applicable to the anodic oxidation coating of aluminum
alloy for construction use.
This part was proposed by the China Nonferrous Metals Industry Association.
This part shall be under the jurisdiction of the National Nonferrous Metals
Standardization Technical Committee.
Responsible drafting organization of this part. Beijing General Research
Institute of Nonferrous Metals.
Participated drafting organizations of this part. Shenzhen Huajiari Aluminum
Co., Ltd., Guangdong Jianmei Aluminum Profile Factory Co., Ltd.
1 Scope
This part specifies the method for assessing the quality of sealed anodic
oxidation coatings of aluminum and aluminum alloy, after nitric acid predip AND
etching in phosphoric acid / chromic acid solution, through the loss of mass.
This part applies to both hot-sealed anodic oxidation coating and cold-sealed
anodic oxidation coating.
This part does not apply to the anodic oxidation coating, which was treated by
the following processes.
a) Hard anodic oxidation coating that is usually not sealed;
b) Anodic oxidation coating that has been sealed in a dichromate solution;
c) Anodic oxidation coating produced in chromic acid solution;
d) Anodic oxidation coating after hydrophobic treatment.
2 Principle of method
For the non-sealed anodic oxidation coating, after predip in nitric acid, it will
quickly dissolve after soaking in the phosphoric acid / chromic acid solution,
whilst the well-sealed oxidation coating will not be etched, even after long time
soaking. For this method, according to this principle, the anodic oxidation
coating is pre-dipped in nitric acid, then etched in a phosphoric acid / chromic
acid solution; the sealing quality is evaluated according to the loss of mass.
3 Reagents
3.1 Pre-dip solution. Pipette 650 mL of nitric acid (rho20 = 1.4 g/mL) into a 1000
mL volumetric flask. Use water to dilute it to the mark.
3.2 Phosphoric acid / chromic acid solution. Dissolve 20 g of chromium trioxide
(CrO3) and 35 mL of phosphoric acid (rho20 = 1.7 g/mL), in 500 mL of water.
4 Instruments
Analytical balance, which has a sensitivity of 0.1 mg.
5 Specimens
5.1 For hot-sealed materials, it may take specimen at any time after sealing.
For cold-sealed materials, it can take specimen after standing for more than 24
hours.
5.2 From the material to be tested, cut a specimen, which has an effective
surface area of about 10000 mm2 (minimum 5000 mm2). Usually, its mass does
not exceed 200 g.
5.3 For hollow extrusions, it shall take specimen from the end of the profile,
which is covered with anodic oxidation coating on both the inner and outer
surface of the test piece.
6 Test procedure
6.1 Measure the effective surface area of the specimen. Use a dry cloth, to wipe
off the frost spots on the surface of the specimen.
6.2 At room temperature, stir the specimen in a suitable organic solvent for 30
seconds OR wipe off the grease. When using a chlorinating agent, such as
perchloroethylene, for degreasing, the pre-drying shall be carried out in a well-
ventilated fume hood, to prevent inhalation of solvent vapor.
6.4 Immediately weigh the specimen mass (m1), accurate to 0.1 mg.
6.5 Fully immerse the specimen upright in the predip solution (3.1), which has
a temperature of 19 °C ± 1 °C. Keep it for 10 minutes.
6.6 Take the specimen out of the predip solution. First use tap water, then
distilled water, to wash it thoroughly clean.
6.7 Put the specimen upright; completely immerse it into the phosphoric acid /
chromic acid solution (3.2), which was preheated to 38 °C ± 1 °C, to soak it for
15 minutes. The solution can be reused; however, each liter of solution, after
processing 1 x 105 mm2 of oxidation coating, shall be discarded. Do not use
solutions, that have been in contact with materials other than the anodic
oxidation coatings of aluminum and aluminum alloy.
6.8 Take out the specimen from the solution. Use tap water, then deionized
water or distilled water, to wash it clean. After drying according to 6.3,
immediately weigh the mass of the specimen (m2), accurate to 0.1 mg.
7 Presentation of results
The mass loss per unit area is calculated by formula (1).
8 Test report
The test report shall include the following.
......
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 7 pages — is available in the English PDF.
Referenced standards
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Related Standards
GB/T 8753.1-2017 — Anodizing of aluminium and its alloys—Assessment of quality of sealed anodic oxidation coatings—Part 1: Measurement of the loss of mass after immersion in acid solution(s)
GB/T 8753.3-2005 — Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 3: Admittance test
GB/T 8753.4-2005 — Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 4: Dye spot test with prior acid treatment
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