Method for coloring a stainless steel
AssigneeNippon Steel Corporation
InventorsTomoo Takahari, Shiyuichi Kondo, Nobumasa Sone, Kengi Hashimoto, Tadashi Ishiguro
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Abstract
A method for coloring a stainless steel using a potential-time curve which comprises seeking for an individual coloring potential difference to be colored by compensating a standard coloring potential difference by difference between a standard inflexion point potential and an individual inflexion point potential, and stopping the coloring when the individual coloring potential changes in an amount corresponding to the individual coloring potential difference from the individual inflexion point potential.
Claims15
In a method for coloring a stainless steel wherein the stainless steel is immersed in a coloring bath for a period of time, the improvement which comprises:
- (a) determining for a given sample of said steel in the bath the difference between the standard inflexion point potential and the potential present when the sample has the desired color, the potentials being determined against a reference electrode immersed in the bath;
- (b) determining the individual inflexion point potential for a sample of the steel to be colored;
- and
- (c) immersing the steel to be colored in the bath for a period of time such that the coloring process is stopped when the potential difference between the individual inflexion point potential and the instantaneous potential is determined by the formula:
- Potential difference
- = potential difference for the standard sample when the sample has the desired color
- .+-. .alpha. (Standard inflexion point potential -- individual inflexion point potential)
- wherein .alpha. is + when a saturated calomel electrode is used and is - when a platinum electrode is used;
- and wherein .alpha. is between 0.23 to 0.36 when the individual inflexion point potential is nobler than the standard inflexion point and is between 0.44 and 0.61 when the individual inflexion point potential is base compared to the standard inflexion point potential.
Dependencies are inferred from the claim text.