Stripping of Phosphate Coatings
Stripping of Phosphate Coatings
(OP)
Anyone know of a method for stripping phosphate coatings (on steel) that does not use chromic acid as the stripping agent?
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Stripping of Phosphate Coatings
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RE: Stripping of Phosphate Coatings
1) Water rinse at 80 °C
2) Immerse for up to 2 min in 55 to 70% sulfuric acid at 20 °C, using a current density of 1000 A/m2
3) Flowing water rinse for 15 to 30 s at room temperature
4) Repeat step 3 in a second tank
5) Dip in 20% hydrochloric acid for 15 s at room temperature
6) Flowing water rinse for 15 to 30 s at room temperature
Regards,
Cory
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RE: Stripping of Phosphate Coatings
Phosphate coatings can be removed with both acids and bases. Do you need a method for evaluating phosphate coating weight or do you just want to remove the coating? If it is the latter, standard products like Chemetall's Gardoclean® S 5171 are used for removing phosphate coatings from fasteners and formed parts prior to heat treating.
RE: Stripping of Phosphate Coatings
RE: Stripping of Phosphate Coatings
RE: Stripping of Phosphate Coatings
RE: Stripping of Phosphate Coatings
RE: Stripping of Phosphate Coatings
You should be testing salt spray ASTM B117 with ASTM D1654 for results. Your auditor should be ok if you are testing panels on a monthly basis. Your chemical supplier and/or paint supplier should be willing to conduct these test for you. Also TCP is correct as far as an electron microspcope to determine if you are achieving the correct crystal structure and density.
20% NaOH and 5% Sodium Gluconate for about 20 minutes at 160F will strip iron phosphate coatings (with minimal chelation of the iron from the substrate) not sure about zinc phosphate. You will need an analytical balance to weigh to 0.1mg
ck1999
RE: Stripping of Phosphate Coatings
RE: Stripping of Phosphate Coatings
ck1999
RE: Stripping of Phosphate Coatings