Coated metal strip
AssigneeThe Louis Berkman Company
InventorsJay F. Carey, II, Mehrooz Zamanzadeh
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Abstract
A weather-resistant strip roofing material having improved corrosion-resistant properties includes a strip of stainless steel which is pre-treated by an aggressive pickling process and/or a chemical activating process prior to applying a hot-dip tin coating, The pre-treatment of the stainless steel strip produces superior alloying between the stainless steel and the tin coating which reduces flaking of the tin coating.
Claims7
A weather resistant stainless steel strip comprising a strip of stainless steel having a thickness up to 0.2 inch and a coating of tin up to 0.05 inch thick, said coating applied to said strip by the process of continuously moving said strip through:
- (a) an oxide removal procedure for removing oxides from said strip surface to provide very low level oxides on said strip surface, said oxide removal procedure includes aggressively pickling said strip surface with a solution of 5-25% hydrochloric acid and 1-15% nitric acid at a temperature of between 80.degree.-140.degree. C. for at least 10 seconds, then chemically activating said strip surface and maintaining a low-oxygen environment about said strip surface during said oxide removal, said aggressively pickling includes subjecting said stainless steel strip to a bath of pickling solution containing hydrochloric acid and nitric acid to said strip surface, said chemical activating includes subjecting said strip to a bath of deoxidizing solution containing zinc chloride;
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- (b) a bath of molten tin having a temperature of at least 449.degree. F. and a lead content of less than 0.02 weight percent lead.
A weather resistant stainless steel strip comprising a strip of stainless steel having a thickness up to 0.2 inch and a coating of tin up to 0.05 inch thick, said coating applied to said strip by the process of continuously moving said strip through:
- (a) an oxide removal procedure for removing oxides from said strip surface, said oxide removal procedure includes aggressively pickling said strip surface then chemically activating said strip surface and maintaining a low-oxygen environment about said strip surface during said oxide removal, said aggressively pickling includes subjecting said stainless steel strip to a bath of pickling solution containing hydrochloric acid and nitric acid to said strip surface, said chemical activating includes subjecting said strip to a bath of deoxidizing solution containing zinc chloride;
- (b) a bath of molten tin having a temperature of at least 449.degree. F. and a lead content of less than 0.02 weight percent lead;
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- (c) said tin coating is coated with an asphalt based paint.
Dependencies are inferred from the claim text.