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.

1 . A process for making a corrosion-resistant metal building component comprising the following steps, regardless of order, of:
 providing a steel sheet, said sheet having a surface comprising zinc or a zinc alloy, suitable for use in making metal building components having an initial thickness,   rolling the steel sheet by at least 10% to form a thinner steel sheet,   forming said rolled steel sheet into at least one metal 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  wherein said building component is selected from the group consisting of galvanized, galvalumed or galvannealed. 
     
     
         3 . The process of  claim 2  where further comprises a step of
 adding a valence stabilizer to said permanganate composition. 
 
     
     
         4 . The process of  claim 1  where the percent rolling is at least 20%. 
     
     
         5 . The process of  claim 4  where the percent rolling is at least 25%. 
     
     
         6 . The process of  claim 1  which further comprises the step of
 adding a surface activator prior to said step of adding a permanganate composition. 
 
     
     
         7 . The process of  claim 1  wherein said inorganic silicate coating is a potassium silicate. 
     
     
         8 . A process for making a corrosion-resistant galvanized light gauge metal building stud comprising the following steps, regardless of order, of:
 providing a galvanized steel sheet having an initial thickness of approximately 0.0295 inches or less;   rolling the steel sheet by at least 10% to form a thinner galvanized steel sheet;   forming said rolled steel sheet into at least one light gauge metal stud;   applying a permanganate conversion coating composition containing essentially no trivalent or hexavalent chromium to said building component, said permanganate composition applied 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 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.   
     
     
         9 . The process of  claim 8  where the percent rolling is at least 20%. 
     
     
         10 . The process of  claim 9  where the percent rolling is at least 25%. 
     
     
         11 . The process of  claim 8  where said permanganate composition is applied at a concentration diluted to up to about 50% of an undiluted composition. 
     
     
         12 . The process of  claim 8  wherein said coating is a potassium silicate. 
     
     
         13 . A process for making a corrosion-resistant building component comprising the following steps, regardless of order, 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,   applying a first coating composition comprising an alkali metal permanganate composition containing essentially no chromium to said building component, 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 building component;   reducing a thickness of said steel sheet by at least 10%;   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.   
     
     
         14 . The process of  claim 13  where building component is a non-structural light gauge galvanized metal building stud. 
     
     
         15 . The process of  claim 13  where said permanganate composition is applied at a concentration diluted to up to about 50% of an undiluted composition. 
     
     
         16 . The process of  claim 13  wherein said alkali metal is K in both said alkali metal permanganate and said alkali metal silicate.