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Treating solution for forming black hexavalent chromium-free chemical coating on zinc or zinc alloy plated substrate, and method for forming black hexavalent chromium-free chemical coating on zinc or

A technology for treating solution and zinc alloy, applied in the field of treating solution of black conversion film, can solve the problems such as the inability to guarantee the corrosion resistance of the finished film and the difficulty in forming a dense film, etc.

Inactive Publication Date: 2006-02-01
DISPOL CHEMICALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method has problems in that it is difficult to stably form a dense film and this method cannot guarantee stable corrosion resistance of the finished film
However, these methods fail to ensure sufficient corrosion resistance of the obtained film compared to conventional hexavalent chromizing treatments.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～6

[0060] The steel plate was galvanized with NZ-98 solution supplied by Dipsol Chemical Co., Ltd. to form a galvanized layer with a thickness of 8 μm, which was immersed in a treatment solution containing trivalent chromium. The composition of the solution is shown in Table 1 below.

[0061] Example number

[0062] In Table 1, the Cr 3+ Source is CrCl 3 (in Examples 1, 2, 3 and 5), CrPO 4 (in Examples 4 and 6) and Cr(NO 3 ) 3 (in Example 5). NO 3 - The concentration of Cr(NO 3 ) 3 (in Example 5) or by adding HNO 3 (in Examples 1, 2 and 3) or NaNO 3 (in Examples 4 and 6) adjustments were made. Again, the SO 4 2- source is Na 2 SO 4 , while the PO 4 3- Source is NaH 2 PO 4 . The balance of each treatment solution was water. The metal salts used, such as Co and Ni, were their sulfates (in Examples 1, 4 and 6) and chlorides (in Examples 2, 3 and 5). The source of Si used was colloidal silica and the source of Ti used was titanium trichloride. The conc...

Embodiment 7～10

[0064] The steel plate is plated with basic zinc-nickel alloy (Ni%: 5-15%) or zinc-iron alloy (Fe%: 0.3-2.0%), with a thickness of 8 μm, and then soaked in a treatment solution containing trivalent chromium. The composition is shown in Table 2 below.

[0065] Example number

7

8

9

10

Cr 3+ (g / L)

4.5

4.5

4.5

4.5

NO 3 · (g / L)

0.6

0.4

0.2

0.4

NO 3 · / Cr 3+ The molar ratio of

0.11 / 1

0.07 / 1

0.04 / 1

0.07 / 1

PO 4 3· (g / L)

12

12

12

15

SO 4 2· (g / L)

10

0

15

2

Cl · (g / L)

0

10

0

0

Oxalic acid (g / L)

15

7

15

15

Malonic acid(g / L)

0

7

0

0

Succinic acid (g / L)

10

0

0

0

Adipic acid(g / L)

0

0

0

20

Chelating agent / Cr 3+ The molar rati...

Embodiment 11-14

[0069] After the trivalent chromizing treatment in Examples 1, 8 and 9, the steel panels were subjected to an overcoat treatment. The conditions of the overcoat treatment used here are summarized in Table 3 below.

[0070] Example number

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Abstract

It is an object of the present invention to provide a processing solution used for forming a hexavalent chromium free, black conversion film, which is applied onto the surface of zinc or zinc alloy plating layers, and which has corrosion resistance identical to or higher than that achieved by the conventional hexavalent chromium-containing conversion film. <??>According to an aspect of the present invention, there is provided a processing solution for forming a hexavalent chromium free, black conversion film on zinc or zinc alloy plating layers, the processing solution comprising: nitrate ions and trivalent chromium in a mole ratio (NO<3-> / Cr<3+>) of less than 0.5 / 1, wherein the trivalent chromium is present in the form of a water-soluble complex with a chelating agent; and cobalt ions and / or nickel ions, wherein the cobalt ions and / or nickel ions are stably present in the processing solution without causing any precipitation by forming a hardly soluble metal salt with the chelating agent; wherein the solution reacts with zinc when it is brought into contact with the zinc or zinc alloy plating to form a hexavalent chromium free, black conversion film containing zinc, chromium, cobalt and / or nickel, and the chelating agent on the plating.

Description

technical field [0001] The invention relates to a treatment solution for forming a black conversion film without hexavalent chromium on a zinc or zinc alloy coating, and a method for forming a black conversion film without hexavalent chromium on the zinc or zinc alloy coating. Background technique [0002] As a metal surface antirust method, a method of galvanizing or zinc alloy plating is known. However, it is impossible to ensure sufficient corrosion resistance of the metal by this plating alone. Therefore, treatment with hexavalent chromium-containing chromic acid or so-called chromate treatment after plating is widely used in this industrial field. Nevertheless, it has recently been pointed out that hexavalent chromium may have negative effects on human body and the environment, and correspondingly there has been a strong and positive trend to demand control of the use of hexavalent chromium. [0003] Therefore, as one of alternative techniques, a method of forming a c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/53C23C22/13C23C22/10C23C22/46C23C22/47C23C28/00
CPCC23C28/3225C23C22/74C23C28/345C23C22/10C23C28/023C23C22/47C23C2222/10C23C22/53C23C22/46C23C28/025
Inventor 井上学中岛亮渡边和宏渡边公隆
Owner DISPOL CHEMICALS CO LTD
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