Claims
- 1. A process for producing a coated steel sheet having excellent corrosion resistance and surface brightness, comprising performing electro-plating in an acidic Zn plating bath containing Cr ions and cation polymer, with the ratio of Cr.sup.6+ ions/Cr.sup.3+ ions being not more than 0.1.
- 2. A process according to claim 1, in which the acidic bath contains at least one member selected from the group consisting of Ni.sup.2+, Fe.sup.2+ and Co.sup.2+.
- 3. A process according to claim 1, in which the acidic bath further contains at least one oxide selected from the group consisting of oxides of Si, Al, Zr, Ti, Cr, Mo and W.
- 4. A process according to claim 1, in which the cation polymer is a quaternary amine polymer.
- 5. A process according to claim 2, in which the acidic bath further contains at least one oxide selected from the group consisting of oxides of Si, Al, Zr, Ti, Cr, Mo and W.
- 6. A process according to claim 2, in which the cation polymer is a quaternary amine polymer.
- 7. A process according to claim 3, in which the cation polymer is a quaternary amine polymer.
- 8. A process according to claim 5, in which the cation polymer is a quaternary amine polymer.
- 9. A process for producing a coated steel sheet having a primer coating and an upper coating, and having excellent corrosion resistance, comprising: a step of electroplating a steel sheet in a plating bath containing Zn.sup.2+ ions, Cr.sup.3+ ions and an organic polymer under a controlled current density so as to differentiate a composition of the primer coating from a composition of the upper coating.
- 10. A process according to claim 9 wherein the primer coating is a complex zinc coating containing 5-30% by weight of Cr, and 0.001 to 5% by weight of the organic polymer, and the upper coating is a complex zinc coating containing 0.01 to less than 5% by weight of Cr and not more than 1% by weight of the organic polymer.
- 11. A process according to claim 9 wherein the plating bath further contains ions of an iron group metal.
- 12. A process according to claim 11 wherein the primer coating is a complex zinc coating containing 5 to 30% by weight of Cr, 1 to 10% by weight of the iron group metal and 0.001 to 5% by weight of the organic polymer, and the upper coating is a complex zinc coating containing 0.001 to less than 5% by weight of Cr, 1 to 10% by weight of the iron group metal, and not more than 1% by weight of the organic polymer.
Priority Claims (6)
Number |
Date |
Country |
Kind |
63-118118 |
May 1988 |
JPX |
|
63-118119 |
May 1988 |
JPX |
|
63-138319 |
Jun 1988 |
JPX |
|
63-191521 |
Jul 1988 |
JPX |
|
63-232265 |
Sep 1988 |
JPX |
|
63-232266 |
Sep 1988 |
JPX |
|
Parent Case Info
This application is a continuation-in-part of Ser. No. 07/642,541 filed Jan. 29, 1991, now allowed, which is a continuation of Ser. No. 07/350,032 filed May 10, 1989, now abandoned.
US Referenced Citations (4)
Foreign Referenced Citations (5)
Number |
Date |
Country |
182964 |
Jun 1986 |
EPX |
2145818 |
Feb 1973 |
FRX |
270799 |
Nov 1987 |
JPX |
14890 |
Jan 1988 |
JPX |
195296 |
Aug 1988 |
JPX |
Non-Patent Literature Citations (1)
Entry |
Chemical Abstracts 101: 119424k. |
Continuations (1)
|
Number |
Date |
Country |
Parent |
350032 |
May 1989 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
642541 |
Jan 1991 |
|