ASTM-B201 › Standard Practice for Testing Chromate Coatings on Zinc and Cadmium Surfaces
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1.1 This practice covers a procedure for evaluating the protective value of chemical and electrochemical conversion coatings produced by chromate treatments of zinc and cadmium surfaces.
1.2 The protective value of a chromate coating is usually determined by salt-spray test and by determining whether or not the coating possesses adequate abrasion resistance.
1.3 Other methods, such as exposure to a humidity environment, can be used, but are generally of too long a duration to be of practical value. “Steam Tests” using pressure cookers have also been used for testing chromate films on hot-dip galvanized surfaces.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Significance and Use
4.1 This practice is applicable to chromate coatings of the colorless (both one and two-dip), iridescent yellow or bronze, olive drab, black, colorless anodic, yellow or black anodic types, and of the dyed variety, when applied to surfaces of electrodeposited zinc, mechanically deposited zinc, hot-dipped zinc, rolled zinc, electrodeposited cadmium, mechanically deposited cadmium, and zinc die castings.
Note 1: Colorless coatings are also referred to as clear-bright or blue-bright coatings.
4.2 Because of variables inherent in the salt-spray test, which may differ from one test cabinet to another, interpretation of test results for compliance with expected performance should be specified by the purchaser.
4.3 Properties such as thickness, color, luster, and ability to provide good paint adhesion are not covered in this practice, nor are the chemical composition and the method of application of these finishes.
ICS Number Code 25.220.40 (Metallic coatings)
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1980 R19 EDITION
April 1, 2019