| 摘要 |
In a process for producing protective coatings on metals of the iron group and their alloys, by immersion in a fused saline bath at temperatures of 475-710 DEG C., the bath consists of potassium dichromate having a proportion of monochromate which is at least as great as that prescribed by the equilibrium ratio set up between the dichromate and monochromate at the temperature at which the bath is to be used, while at the same time not being so great that the bath ceases to be in a completely fused condition. The desired proportion of monochromate may be added to the bath or may be produced by the addition by corresponding additions of salts, such as potassium nitrate, which are capable of transforming the dichromate into the monochromate. The potassium salts may be replaced wholly or partially by the sodium salts. Specification 477,836 is referred to. |
