Chromium hydroxide, method for producing the same, trivalent chromium-containing solution using the same, and chromium plating method

A technology for chromium hydroxide, manufacturing methods, applications in chromium oxide/hydrate, nanotechnology for materials and surface science, transportation and packaging, etc.

Inactive Publication Date: 2010-08-04
NIPPON CHECMICAL IND CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, there is no description of the solubility of the obtained chromium hydroxide
[0013] Unlike the above production methods, Patent Document 7 discloses chromium (III) salts of various inorganic acids, but there is no description about chromium hydroxide

Method used

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  • Chromium hydroxide, method for producing the same, trivalent chromium-containing solution using the same, and chromium plating method
  • Chromium hydroxide, method for producing the same, trivalent chromium-containing solution using the same, and chromium plating method
  • Chromium hydroxide, method for producing the same, trivalent chromium-containing solution using the same, and chromium plating method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1～6

[0080] 140 g of 10% sodium hydroxide aqueous solution and 52 g of 35% chromium chloride aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd.) were added to the container and diluted with 208 g of water to obtain a 7% chromium chloride aqueous solution for preparation. Next, the aqueous sodium hydroxide solution and the aqueous chromium chloride solution were adjusted to the temperatures shown in Table 1. While stirring the sodium hydroxide aqueous solution at the speed shown in Table 1, the chromium chloride aqueous solution was added thereto at the speed shown in Table 1. Addition was performed until the pH of the reaction system reached the value shown in the same table. The generated precipitate was filtered and washed with water at 30° C. until the conductivity of the filtrate reached 1 mS / cm to obtain about 12 g of chromium hydroxide. This chromium hydroxide was suspended in pure water to obtain a slurry with a concentration of 8%. The solubility and deg...

Embodiment 7～9 and comparative example 14～17

[0093] Except having set the stirring rate at the time of adding the chromium chloride aqueous solution to the conditions shown in Table 4, the same operation as Examples 1-6 was performed, and the slurry containing chromium hydroxide and chromium hydroxide was obtained. The solubility, average particle diameter, and degree of aggregation of the obtained chromium hydroxide were measured in the same manner as in Examples 1 to 6. However, the solubility was measured immediately after generation of chromium hydroxide, and was measured after storage for 7 days. The results are shown in Table 4. In these comparative examples, since the stirring speed was lower than that of the examples, the amount of trivalent chromium was locally excessive relative to the amount of the alkali, and the obtained chromium hydroxide had poor solubility in acidic solutions.

[0094] [Table 4]

[0095]

Embodiment 10

[0097] Except having used 195 g of 10% potassium hydroxide aqueous solution instead of sodium hydroxide aqueous solution, the same operation as Example 3 was performed, and the slurry containing chromium hydroxide and chromium hydroxide was obtained. The solubility, average particle diameter, and degree of aggregation of the obtained chromium hydroxide were measured in the same manner as in Examples 1 to 6. The results are shown in Table 5.

[0098] [table 5]

[0099]

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Abstract

Disclosed is a chromium hydroxide which is characterized by having an average particle diameter D of 40-200 nm and an aggregation degree, which is represented by the ratio D50 / D between the volume average particle diameter D50 measured by a particle size distribution measuring instrument and the average particle diameter D determined by a scanning electron microscopic image, of not less than 10 but less than 70. This chromium hydroxide is suitably obtained by adding an aqueous solution containing trivalent chromium into an inorganic aqueous alkaline solution under such a condition that the temperature of the reaction liquid is not less than 0 DEG C but less than 50 DEG C. A hydroxide of an alkali metal is preferably used as the inorganic alkali.

Description

technical field [0001] The present invention relates to chromium hydroxide and its preparation method. The present invention also relates to a trivalent chromium-containing liquid and a chromium plating method using the chromium hydroxide. Background technique [0002] Chromium plating is used in various industrial fields for decoration and industry. Because chrome plating is not corroded in the atmosphere and does not lose its luster, it is widely used as a decorative plating. In addition, due to its high hardness and low coefficient of friction, it is widely used in mechanical parts and the like that require wear resistance. The plating solution used in this electroplating method uses a large amount of hexavalent chromium. Since hexavalent chromium may have an impact on the human body, it cannot be discharged into the environment when the electroplating waste solution is disposed of, and it must be reduced to trivalent chromium under very strict conditions. Therefore, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/02C25D21/14C25D3/06
CPCC25D21/14C01P2004/64C01P2004/03C01P2004/04C01P2004/51C01P2004/62C25D3/06C01G37/02B82Y30/00C01P2006/80Y10T428/2982
Inventor 星野重夫真保良吉田中保之
Owner NIPPON CHECMICAL IND CO LTD
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