NPFC - TT-C-490
CHEMICAL CONVERSION COATINGS AND PRETREATMENTS FOR FERROUS SURFACES (BASE FOR ORGANIC COATINGS)
| Organization: | NPFC |
| Publication Date: | 31 March 1993 |
| Status: | inactive |
| Page Count: | 19 |
scope:
This specification covers cleaning, surface conditioning, and preconditioning methods for improving the corrosion resistance of ferrous metals. The application of chemical conversion and pretreatment coatings provides uniformly textured substrates for receiving and retaining paint, lacquer, etc. In addition, this specification covers suitable cleaning processes for nonferrous surfaces (see 6.1, 6.1.2).
This specification covers the following cleaning methods and surface pretreatment processes:
Surface cleaning shall be by any of the following methods as specified (see 6.4):
Method I - Mechanical or abrasive cleaning (for ferrous surfaces only). Method II - Solvent (immersion, spray or vapor). Method III - Hot alkaline (immersion, spray or electrolytic, for ferrous surfaces only). Method IV - Emulsion (with or without added water). Method V - Alkaline derusting (for ferrous surfaces only). Method VI - Phosphoric acid (alcoholic, detergent or solvent type with detergent).
Chemical conversion and pretreatment coatings shall be of the following types as specified (see 6.4).
Type I - Zinc phosphate spray application (150 mg/sq ft min - 500 mg/sq ft max)
Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: U.S. Army Research Laboratory, Materials Directorate, Materials Standardization Office, ATTN: AMSRL-MA-S, Watertown, MA 02172-0001 by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.
- Zinc phosphate immersion or dip application (300 mg/sq ft min - 500 mg/sq ft max) Type II - Aqueous iron phosphate (35 mg/sq ft min) Type III - Organic pretreatment coating (unless otherwise specified, MIL-C-8514 or DOD-P-15328) Type IV - Non-aqueous iron phosphate (35 mg/sq ft min) Type V - Zinc phosphate (500 mg/sq ft min - 1100 mg/sq ft max)
New design documents, engineering drawings and ordering data shall indicate the type of coating required and method of application when applicable.
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