1.1 These practices cover two classes of treatment for preparation of magnesium alloy surfaces for painting, as follows:
Class I-Chemical Treatments.
Class II-Anodic Treatments.
In general, the latter treatments are the more protective of the two classes. Mechanical (abrasive) treatments, solvent cleaning, alkaline solution treatments, and acid pickles not resulting in protective conversion coatings are suitable preliminary treatments only for metal to be exposed under mildly corrosive (indoor) exposures. When a high degree of corrosion protection and paint adhesion are desired, as in many outdoor environments, surface preparation by one of the above conversion-coat classes is necessary. The hexavalent chromium based methods given are not recommended as hexavalent chromium is a known carcinogen.
Product Details
- Published:
- 05/01/2013
- Number of Pages:
- 8
- File Size:
- 1 file , 110 KB
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This specification covers chemical treatments and anodic treatments for preparation of magnesium alloy surfaces for printing. The procedure for preliminary treatment of surfaces using alkaline cleaners and acid cleaners are presented. Class I, type I (chrome pickle) surface preparation procedure is applicable to all forms of magnesium except certain special alloys containing silver. Class I, type II (sealed chrome pickle) surface preparation procedure is applicable to all types and forms of magnesium-based alloys, subject only to the limitations of class I, type I treatment. Class I, type III treatment is applicable to all types and forms of magnesium-based alloys except M1 alloy and certain rare-earth alloys similar to EK30A. Class II, type I (galvanic dichromate treatment) produce black coatings of good protective and pain-base qualities, and is applicable to all alloys and forms of magnesium, including M1 alloy. Class II, type II treatment is applicable to all forms and alloys of magnesium. Class II, type III treatment is applicable to all forms and alloys of magnesium, free from attachments or inserts of other metals.
Product Details
- Published:
- 10/01/2018
- Number of Pages:
- 8
- File Size:
- 1 file , 120 KB