Room temperature blackening solution
AssigneeMitchell Bradford International Corp.
InventorPaul Jarvi
Life of this patent
Estimating the term…
Abstract
A room temperature black coating for ferrous metal is formed in a solution based on selenium dioxide, an inorganic copper salt and an organic acid. The solution virtually eliminates the formation of a selenium iron precipitate which results from conventional blackening agents in which an inorganic acid such as phosphoric, sulfuric, nitric or hydrochloric acid is used. Further, the virtual elimination of the precipitate produces the additional benefit that the user needs handle and ultimately dispose of only an insignificant amount of toxic selenium iron or selenium phosphate compound materials.
Claims16
In a room temperature blackening solution comprising a selenium dioxide, inorganic copper salt, acid, and water, the improvement which comprises employing an organic acid as said acid.
In a room temperature blackening solution comprising a selenium dioxide, inorganic copper salt, acid, and water, the improvement wherein said solution contains:
- ______________________________________ selenium dioxide anhydrous 25-35 gram/liter copper sulfate pentadydrate 10-20 gram/liter ammonium nitrate anhydrous 5-15 gram/liter sulfamic acid anhydrous 10-30 gram/liter polyoxyethylene ether alcohol 1 gram/liter. ______________________________________
In a method for forming a black coating on a ferrous metal substrate comprising contacting the substrate with a blackening solution comprised of selenium dioxides, inorganic copper salt, acid, and water, the improvement which comprises employing an organic acid as said acid;
- and immersing said ferrous metal in said solution.
In a method for forming a black coating on a ferrous metal substrate comprising coating the substrate with a blackening solution comprised of selenium dioxides, inorganic copper salt, acid, and water the improvement which comprises employing a sulfamic acid as said acid;
- and immersing said ferrous metal in said solution.
In a method for forming a black coating on a ferrous metal substrate comprising coating the substrate with a blackening solution comprised of selenium dioxides, inorganic copper salt, acid, and water, the improvement which comprises employing an organic acid as said acid;
- immersing said ferrous metal in said solution;
- said blackening solution being a concentrate which is diluted with water and has a concentration in the range of 5% to 20% by volume.
Dependencies are inferred from the claim text.