GB/T 8753.4-2005Anodizing of aluminium and aluminium alloys -- Assessment of quality of sealed anodic oxide coatings -- Part 4: Dye spot test with prior acid treatment (English PDF)

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 4 of GB/T 8753.

This part modifies and adopts ISO 2143:1981 "Anodizing of aluminum and its

alloys - Estimation of loss of absorptive power of anodic oxide coatings after

sealing - Dye spot test with prior acid treatment" (English version). It is re-

drafted according to ISO 2143:1981. The difference between this part and ISO

2143:1981 is reflected in the compilation format. For the convenience of

comparison, a comparison of clause numbers BETWEEN this part AND the

corresponding international standard, is listed in the informative Appendix A.

This part replaces GB/T 8753-1988 "Anodizing of aluminum and aluminum

alloys - Estimation of loss of absorptive power of anodic oxide coatings after

sealing - Dye spot test with prior acid treatment". The difference between this

part and GB/T 8753-1988 is mainly reflected in the compilation format.

This part is suitable for the production control inspection of anodic oxidation,

which is a non-destructive testing method.

For the the methods specified in this part, although they can be graded based

on dye spots, the quantitative data is not accurate. It is not suitable to be an

arbitration test.

Appendix A of this part is an informative Appendix.

This part was proposed by the China Nonferrous Metals Industry Association.

Anodizing of aluminum and its alloys - Assessment of

quality of sealed anodic oxidation coatings - Part 4:

Dye spot test with prior acid treatment

1 Scope

This part specifies the method for assessing the quality of sealed anodic

oxidation coatings, by the anti-dying adsorption ability, after acid treatment.

This part is applicable to the production control inspection of anodic oxidation

coating, with anti-pollution ability, which is subject to atmospheric sun-exposure

or corrosive environment.

This part does not apply to the anodic oxidation coating, which is produced by

the following aluminum alloys:

a) Anodic oxidation coating, which has a copper content > 2% AND silicon

content > 4%;

b) Oxidation coating which is sealed by potassium dichromate;

c) Oxidation coating which is treated by oiling, waxing, painting;

d) Dark oxidation coating;

e) Oxidation coating, which has a thickness of less than 3 µm.

When the sealing solution contains nickel, cobalt or other organic additives, this

method is not effective enough.

2 Principle of method

In this method, the degreased surface of the specimen is first subject to acid

treatment; then it is colored by a dye, to observe the dyeing condition. According

to the loss of the dyeing adsorption capacity of the oxidation coating, assess

the anti-dyeing absorption capacity of the anodic oxidation coating.

The anti-dyeing adsorption capacity of the anodic oxidation coating is one of

the methods to assess the sealing quality. Under normal circumstances, the

strong anti-dyeing adsorption capacity indicates good sealing quality. However,

a slight decrease in the anti-dyeing adsorption capacity, does not mean that the

sealing quality of the oxidation coating is deteriorated, because the anti-dyeing

adsorption capacity is sometimes related to other factors.

3 Solution

The test solution shall be prepared by analytical reagents and distilled water (or

deionized water). The acid solutions, which are listed in 3.1 and 3.2, can be

equivalently applied to any kind of dye spot test. However, the solution which is

specified in 3.4 is safer. When using the container, which is made of anti-fluoric

acid material, to store the acid solution, it must be careful during operation.

4 Specimen

The specimen is generally cut directly from the product. If a specially prepared

specimen is used, even if its production process is the same as the product, it

will produce some erroneous results.

5 Test procedure