Zinc phosphate coating process
US4053328A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 25, 1975 |
| Grant date | Oct 11, 1977 |
| Priority date | — |
| Expiry date | Aug 25, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C22/13
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Zinc phosphate coating solution contains phosphate ions in an amount of at least 0.5 percent by weight and in the phosphate ion to nitrate ion molar weight ratio of from 1 : 0.7 to 1 : 1.3. This solution also contains zinc ions in an amount, preferably, of at least 0.03 percent by weight and in a ratio of zinc ion to phosphate ion of less than 0.116 to 1. Nickel ions may be added in an amount of at least 0.01 percent by weight and in the nickel ion to zinc ion ratio of less than 1.89 to 1. The pH value of this solution ranges from about pH 3.3 to pH 3.8, whereby the consumption of nitrites employed as accelerators is reduced and sludges are formed in less amounts as in the form easily removable from an apparatus where the phosphating is effected. The zinc phosphate coating solution is preferably employed for an apparatus in which little or no solution is discharged out of the phosphating system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.