Heavy Phosphate Coating Specification Review

DOD-P-16232-F, Heavy Phosphate Coating

Heavy Phosphate Coating is a coating for medium and low alloy steels. Gray to black in color. Intended uses: The "heavy" phosphate coatings covered by this specification are intended as a base for holding/retaining supplemental coatings which provide the major portion of the corrosion resistance.

• Heavy Type Z can be used up to 200 F, to prevent galling in extrusion and deep drawing.
• Class 2 is good for corrosion resistance. 
• Note: This specification lists a type M also
• Type Z   .0002" Zinc phosphate base coating
• Class 1   .0005" Supplementary preservative treatment or coating, as specified.
• Class 2  Supplementary treatment with preservative conforming to MIL-C-16173, Grade 3 or MIL-L-3150  as alternate for very small parts.
• Class 3  No supplementary treatment.
• Class 4  Chemically converted.

Download: DOD-P-16232, Heavy Phosphate Coating