Method for improving light gauge building materials

Abstract

A process is described in which non-structural galvanized steel studs are sequentially chemically treated with a permanganate coating to improve oxidation resistance, followed by treatment with a silicate coating sealant, optionally with zinc surface activation using an acid treatment.

What is claimed is: 
     
         1 . A process for making a corrosion-resistant metal building component comprising the following steps of:
 providing a steel sheet, said sheet having a surface comprising zinc or a zinc alloy selected from the group consisting of galvanized, galvalumed and galvannealed, suitable for use in making metal building components having an initial thickness,   rolling the steel sheet by at least 10% to form a rolled steel sheet in forming a building component,   applying a permanganate coating composition containing essentially no trivalent or hexavalent chromium to said building component, at a pH of about 9.0 to 2.0 inclusive; and   applying an inorganic silicate coating to seal said permanganate composition on said building component, such that the building component meets the ASTM B 117-07a test and provides a corrosion resistance similar to a like building component made of the initial thickness without the rolling step.   
     
     
         2 . The process of  claim 1  where a permanganate coating is applied to the steel sheet. 
     
     
         3 . The process of  claim 1  where the initial thickness is 0.017-0.115 inches. 
     
     
         4 . The process of  claim 1  where the method further comprises a step of adding a valence stabilizer to said permanganate composition. 
     
     
         5 . The process of  claim 1  where the percent rolling is at least 20%. 
     
     
         6 . The process of  claim 1  where the percent rolling is at least 25%. 
     
     
         7 . The process of  claim 1  which further comprises the step of adding a surface activator prior to said step of adding a permanganate composition. 
     
     
         8 . The process of  claim 1  wherein said inorganic silicate coating is a potassium silicate. 
     
     
         9 . A process for making a corrosion-resistant galvanized light gauge metal building stud comprising the following steps of:
 providing a steel sheet having a surface comprising zinc or a zinc alloy and having an initial thickness of 0.017-0.115 inches;   applying a permanganate conversion coating composition containing essentially no trivalent or hexavalent chromium to said galvanized steel sheet, said permanganate composition applied at a pH of about 9.0 to 2.0 inclusive;   rolling the steel sheet by at least 10% to form a thinner galvanized steel sheet in forming at least one light gauge metal stud; and   applying an inorganic silicate coating to seal said permanganate composition on said at least one light gauge metal stud, such that the light gauge metal stud meets the ASTM B 117-07a test and provides a corrosion resistance similar to a metal stud made of the initial thickness without the rolling step.   
     
     
         10 . The process of  claim 9  where the sheet surface is selected from the group consisting of galvanized, galvalumed and galvannealed. 
     
     
         11 . The process of  claim 9  where the initial thickness is approximately 0.0295 inches. inches. 
     
     
         12 . The process of  claim 9  where the percent rolling is at least 20%. 
     
     
         13 . The process of  claim 9  where the percent rolling is at least 25%. 
     
     
         14 . The process of  claim 9  where said permanganate composition is applied at a concentration diluted to up to about 50% of undiluted permanganate composition. 
     
     
         15 . The process of  claim 9  wherein said coating is a potassium silicate. 
     
     
         16 . A process for making a corrosion-resistant building component comprising the following steps of:
 providing a steel sheet suitable for use in making metal building components, said sheet having a surface comprising zinc or a zinc alloy, suitable for use in making metal building components having an initial thickness,   reducing a thickness of said steel sheet by at least 10% to form a reduced thickness steel sheet;   applying a first coating composition comprising an alkali metal permanganate composition containing essentially no chromium to said steel sheet, and wherein said alkali metal of said alkali metal permanganate composition is selected from the group consisting of potassium, sodium, lithium, rubidium and cesium and applied at a pH of about 9.0 to 2.0 inclusive;   applying a second coating composition comprising a silicate sealant composition to the steel sheet;   forming said reduced thickness steel sheet into at least one metal building component and wherein said building material meets the ASTM B 117-07a corrosion-resistance standard at a coating weight which is equal to or less than that specified by ASTM A 1003-G40.   
     
     
         17 . The process of  claim 16  where the first coating is applied before rolling the steel sheet. 
     
     
         18 . The process of  claim 16  where building component is a non-structural light gauge galvanized metal building stud. 
     
     
         19 . The process of  claim 16  where said permanganate composition is applied at a concentration diluted to up to about 50% of undiluted permanganate composition. 
     
     
         20 . The process of  claim 16  wherein said alkali metal is potassium in both said alkali metal permanganate and said silicate.