GB/T 8753.2-2005 PDF in English
GB/T 8753.2-2005 (GB/T8753.2-2005, GBT 8753.2-2005, GBT8753.2-2005)
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| GB/T 8753.2-2005 | English | 90 |
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Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 2: Phosphoric acid/chromic acid test
| Obsolete |
Standards related to (historical): GB/T 8753.2-2005
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GB/T 8753.2-2005: PDF in English (GBT 8753.2-2005) GB/T 8753.2-2005
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.220.20
H 21
Replacing GB/T 14952.2-1994
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
ISSUED ON: JULY 04, 2005
IMPLEMENTED ON: DECEMBER 01, 2005
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Replaced
Table of 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.
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
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 (ρ20 = 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 (ρ20 = 1.7 g/mL), in 500 mL of water.
Transfer it into a 1000 mL volumetric flask. Use water to dilute it to the mark.
Mix it uniformly.
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. In special cases (such as certain types of fixtures,
small hollow profiles, etc.), it shall remove the anodic oxidation coating from the
inner surface; carry out the test on the outer surface.
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.
Note: The predip solution and test solution do not etch the base metal, so there is no
need to consider the surface without oxidation coating.
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.
6.3 Drying the specimen: First, dry the specimen at room temperature (pre-
drying) for 5 minutes. Then place the specimen upright in a drying oven, which
had been preheated to 60 °C, to dry it for 15 minutes. Then place it above the
silica gel in a sealed drying oven, to cool it for 30 min.
6.4 Immediately weigh the specimen mass (m1), accurate to 0.1 mg.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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