Trivalent chromium chemical conversion treatment liquid for zinc or zinc alloy base and chemical conversion treatment method using the same

Inactive Publication Date: 2019-03-14
DISPOL CHEMICALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a chemical treatment liquid for zinc or zinc alloy that is environmentally friendly, resistant to corrosion, and has a uniform appearance without any white haze. This liquid contains no hexavalent chromium or cobalt. Its use results in a silver-white coating that is effective in protecting against corrosion.

Problems solved by technology

However, the coating of chemical conversion treatment represented by the chromic acid, chromate chemical conversion treatment partly contains harmful hexavalent chromium.

Method used

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  • Trivalent chromium chemical conversion treatment liquid for zinc or zinc alloy base and chemical conversion treatment method using the same

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0039]A chemical conversion treatment liquid was prepared as specified below, and the pH of the liquid was adjusted to 3.7 with ammonia water. Thereafter, the above test specimen was dipped in the chemical conversion treatment liquid at 35° C. for 60 seconds.

(A) 40% chromium nitrate: 5.4 g / L (9 mmol / L in terms of Cr3+ ions and 27 mmol / L in terms of NO3− ions)

(B) Potassium fluorozirconate: 2.0 g / L (7 mmol / L in terms of Zr ions)

(C) Ammonium nitrate: 4.8 g / L (60 mmol / L in terms of NO3− ions)

(D) Chain colloidal silica (diameter of 40-100 nm): 20.0 g / L (50 mmol / L)

The residue is water.

example 2

[0040]A chemical conversion treatment liquid was prepared as specified below, and the pH of the liquid was adjusted to 3.5 with ammonia water. Thereafter, the above test specimen was dipped in the chemical conversion treatment liquid at 45° C. for 40 seconds.

(A) 35% chromium chloride: 9.0 g / L (20 mmol / L in terms of Cr3+ ions)

(B) 40% zirconium fluoride: 7.8 g / L (15 mmol / L in terms of Zr ions)

(C) Sodium nitrate: 7.2 g / L (85 mmol / L in terms of NO3− ions)

[0041]Zinc nitrate hexahydrate: 0.75 g / L (5 mmol / L in terms of NO3− ions)

(D) Chain colloidal silica (diameter of 40-100 nm): 40.0 g / L (100 mmol / L)

The residue is water.

example 3

[0042]A chemical conversion treatment liquid was prepared as specified below, and the pH of the liquid was adjusted to 3.5 with ammonia water. Thereafter, the above test specimen was dipped in the chemical conversion treatment liquid at 40° C. for 30 seconds.

(A) 40% chromium sulfate: 8.8 g / L (18 mmol / L in terms of Cr3+ ions)

(B) Ammonium hexafluorozirconate: 2.4 g / L (10 mmol / L in terms of Zr ions)

(C) Ammonium nitrate: 12.0 g / L (150 mmol / L in terms of NO3− ions)

(D) Chain colloidal silica (diameter of 40-100 nm): 64.0 g / L (160 mmol / L)

The residue is water.

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Abstract

An object is to provide a trivalent chromium chemical conversion treatment liquid for a zinc or zinc alloy base capable of forming an environmentally-friendly chemical conversion coating with high corrosion resistance. The present invention provides a hexavalent chromium-free trivalent chromium chemical conversion treatment liquid for zinc or zinc alloy, the liquid comprising trivalent chromium ions, zirconium ions, nitrate ions, and chain colloidal silica, in which the pH of the treatment liquid is 2.5 to 5.0.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of and priority to Japanese Patent Application No. 2017-177016, filed on Sep. 14, 2017, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD[0002]The present invention relates to a novel chemical conversion treatment liquid for forming a silver-white chemical coating finished with uniform and haze-free (white haze-free) appearance and having excellent corrosion resistance on the surface of a zinc or zinc alloy metal, and relates to a chemical conversion treatment method using the same.BACKGROUND ART[0003]Chemical conversion treatment is a technique that has been used from old times to impart corrosion resistance to metal surfaces, and is also currently used for surface treatment for aircraft, construction materials, automobile parts, and the like. However, the coating of chemical conversion treatment represented by the chromic acid, chromate chemical conversion treatment partly conta...

Claims

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Application Information

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IPC IPC(8): C23C22/53
CPCC23C22/53C23C2222/10C23C22/34C23C22/06B82Y30/00
Inventor IWANAGA, RYOUJIINOUE, MANABUYAMAMOTO, TOMITAKAFUJINO, TAKAHIRO
Owner DISPOL CHEMICALS CO LTD
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