GB/T 6465-2008 in English

GB/T 6465:2008 Metallic and other non-organic coatings - Corrodkote corrosion test (CORR test) English

1 Scope

This standard specifies the reagent, the apparatus and the procedure for assessment of the quality of metallic and other non-organic coatings.

The method is primarily applicable to copper-nickel-chromium or nickel-chromium electroplated parts.

2 Normative references

The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the latest editions of the standards indicated below. For undated references, the latest edition of the document referred to applies.

GB/T 6461 Methods for corrosion testing of metallic and other inorganic coatings on metallic substrates - Rating of test specimens and manufactured articles subjected to corrosion tests (GB/T 6461-2002, ISO 10289: 1999, IDT)
GB/T 10125 Corrosion tests in artificial atmospheres - Salt spray tests (GB/T 10125-1997, eqv ISO 9227: 1990)

3 Principle

Application of a slurry containing corrosive salts to test specimens, allowing the slurry to dry, and exposure of the coated specimens to a high relative humidity for a specified period of time.

4 Preparation of Corrodkote slurry

Prepare the Corrodkote slurry in a glass beaker by dissolving 0.035 g of reagent grade copper (II) nitrate trihydrate [Cu (NO)3)2·3H2O], 0.165 g of reagent grade iron (III) chloride hexahydrate [FeCl]3·6H2O] and 1.0 g of reagent grade ammonium chloride [NH4Cl] in 50.0 mL of distilled water, stirring into the solution 30.0 g of water-washed ceramic grade kaolin. Mix the slurry thoroughly with a glass stirring rod and allow it to stand for 2 min so that the kaolin becomes saturated. Mix the slurry thoroughly with a glass stirring rod just before using.

Note 1: An alternative method of preparing Corrodkote slurry is as follows: Weigh 2.50 g of copper (II) nitrate trihydrate [Cu (NO)3)2·3H2O] and dilute with distilled water to the mark in a 500 mL one-mark volumetric flask. Weigh 2.50 g of iron (III) chloride hexahydrate [FeCl3·6H2O], and dilute with distilled water to the mark in a 500 mL one-mark volumetric flask. Weigh 50.0 g of ammonium chloride [NH4Cl] and dilute with distilled water to the mark in a 500 mL one-mark volumetric flask. Then transfer exactly 7.0 mL of the copper (II) nitrate solution, 33.0 mL of the iron (III) chloride solution and 10.1 mL of ammonium chloride solution to a beaker and add 30.0 g of kaolin. Stir with a glass stirring rod.

Note 2: Keep the iron (III) chloride solution in the dark in a flask fitted with a rubber or glass stopper. The iron (III) chloride solution shall not be more than two weeks old, since older solutions become unstable.

5 Apparatus

5.1 The apparatus shall consist of a humidity chamber, specimen supports, heating device and air circulating device.

5.2 The chamber shall be designed such that drops of moisture which might accumulate on the roof or walls of the chamber, or on the specimen supports, do not fall on the test specimens.

5.3 The materials of construction shall be such as not to affect the test.

6 Test specimens

6.1 Type and number of test specimens to be used, as well as the criteria for evaluation of the test results are determined according to the specification for the coating or products being tested.

6.2 Prior to test, the test specimens may be cleaned using a suitable solvent such as ethanol, diethyl ether, acetone or light petroleum. Do not use solvents that are corrosive or that deposit protective films.

6.3 Apply the Corrodkote slurry to the test specimens using a clean (paint) brush. Dip the brush in the Corrodkote slurry and, with a circular motion, completely cover the test specimen. Then smooth out the coating by brushing lightly in one direction. The wet film thickness shall be not less than 0.08 mm and not greater than 0.2 mm. Allow the test specimens to dry at ambient temperature and at a relative humidity less than 50% for 1 h before placing them in the humidity chamber.

Foreword i
Introduction ii
1 Scope
2 Normative references
3 Principle
4 Preparation of Corrodkote slurry
5 Apparatus
6 Test specimens
7 Position of test specimens during test
8 Conditions in the humidity chamber
9 Test cycle
10 Period of test
11 Treatment of test specimens after test
12 Evaluation of results
13 Test report