Lubricant system for cold forming, process and composition therefor

Abstract

The invention is directed to a combination of a conditioner bath and a calcium modified zinc phosphating solution optionally containing hydroxylamine which provide an improved phosphate coating on the surface of ferrous metal articles. In a preferred embodiment, the treatment process further comprises coating the workpiece with a second lubricant. The three treatments work together to provide finer grained phosphate coatings, longer life of the second lubricant bath and improved adherence of the second lubricant, as compared to a similar phosphating bath that is used alone or with a similar second lubricant.

1 . A process for lubricating a ferrous-base metal article in preparation for cold forming comprising the steps of contacting a surface of the ferrous-base metal article with a conditioning rinse; thereafter contacting the conditioned surface with a first lubricant which comprises an aqueous acidic lubricating phosphate coating solution containing calcium, and optionally hydroxylamine, thereby forming a phosphate coating comprising less than 0.5 wt % calcium on the surface of the metal article.  
   
   
       2 . The process of  claim 1  wherein the conditioning rinse comprises the reaction product of a titanium compound and a phosphate compound in aqueous dispersion with at least one alkaline builder and a surfactant.  
   
   
       3 . The process of  claim 1  comprising the additional step of applying a second lubricant to the phosphate coated metal article.  
   
   
       4 . The process of  claim 1  wherein the ratio of Ca:Zn ranges from about 0.05 to about 2.  
   
   
       5 . The process of  claim 1  wherein calcium in the phosphating bath is present in amounts ranging between about 0.05-15 weight percent.  
   
   
       6 . The process of  claim 1  wherein the phosphate coating has a platelet-type morphology with crystals ranging in size from about 5-25 microns.  
   
   
       7 . An article of manufacture made according to  claim 1 , wherein the phosphate coating comprises less than 0.2 wt % calcium.  
   
   
       8 . An article of manufacture comprising: 
 a. a ferrous-base metal article having an outer surface,    b. a first lubricant layer deposited on said outer surface, the first lubricant layer comprising a uniform layer of phosphate conversion coating comprising less than 0.5 wt % calcium and having an average grain size of 5-25 microns; and    c. a second lubricant layer adhered to outer surfaces of said first lubricant layer, the second lubricant layer comprising reaction products of at least one metal in the conversion coating and at least one of a reactive soap, fatty acid and fatty acid salt.    
   
   
       9 . The article of manufacture of  claim 8 , wherein the first lubricant layer comprises one or more of zinc phosphate, manganese phosphate, nickel phosphate, iron phosphate, or mixtures thereof.  
   
   
       10 . The article of manufacture of  claim 8  wherein crystals in the phosphate conversion coating have platelet-type morphology.  
   
   
       11 . The article of manufacture of  claim 8  having a coating weight in the range of about 250 to about 6000 milligrams of coating per square foot of metal surface.  
   
   
       12 . The article of manufacture of  claim 8 , wherein the reactive soap, fatty acid or fatty acid salt is selected from the group consisting of a C.sub.8 to C.sub.18 fatty acid, fatty acid salt, fatty acid soap, or mixtures thereof.  
   
   
       13 . The article of manufacture of  claim 12 , wherein the reactive soap, fatty acid or fatty acid salt is selected from the group consisting of sodium stearate, potassium stearate, or mixtures thereof.  
   
   
       14 . A process for cold-forming a ferrous-base metal article comprising the steps of: 
 a. contacting the surface of the ferrous-base metal article with a conditioning rinse;    b. contacting the conditioned surface with an aqueous acidic phosphate coating solution containing effective amounts of calcium, and optionally hydroxylamine, thereby forming a phosphate coating, having a measurable coating weight, on said metal article comprising less than 0.5 wt % calcium and having an average grain size of 5-25 microns;    c. optionally, coating the phosphate coated metal article with an excess of a second lubricant and drying the second lubricant on the phosphate coated metal article, thereby forming a measurable amount of reacted second lubricant on the article; and    d. subjecting the coated article to cold deformation.    
   
   
       15 . The process of  claim 14 , wherein the aqueous acidic phosphate coating solution comprises an aqueous acidic zinc, manganese or zinc/manganese lubricating phosphate coating solution.  
   
   
       16 . The process of  claim 14 , wherein the coated article's reactive lube efficiency prior to step (d) is greater than a similar coated article's reactive lube efficiency, said similar coated article being produced, without a conditioning rinse, under otherwise substantially identical phosphating conditions.  
   
   
       17 . The process of  claim 14 , wherein the second lubricant which contains a fatty acid, fatty acid salt, fatty acid soap, or mixtures thereof.  
   
   
       18 . An article of manufacture made according to  claim 14 , wherein the phosphate coating comprises less than 0.2 wt % calcium.