| Patents for C23C 22 - Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals (14,001) | |
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| 01/1976 | |
| 01/06/1976 | US3930897 Method of treating an object of silicon steel provided with an insulating protective coating of silicate with a solution of phosphate |