JPS58224200A - Stripping method of rhodium - Google Patents

Abstract

PURPOSE:To remove thoroughly an Rh coated surface and to make easy the reconditioning and mending of product by immersing article having the Rh surface in a sulfuric acid bath of a specified concn., and subjecting the same to AC electrolysis then washing the deposits stuck on the surface. CONSTITUTION:Article formed with an Rh film by plating, sputtering, vacuum deposition or the like are immersed in a bath of 50-100V% concn. of sulfuric acid and are subjected to AC electrolysis. The black material (oxide of the base metal) adsorbed on the object surface after conduction of electricity for a specified time is washed away ultrasonically, brushing, rubbing or the like, and electricity is conducted again. The operation is repeated until the Rh coating is removed thoroughly from the article surface. The Rh film is stripped easily by the above-mentioned method without damaging the base metal. The method adaptable is to all Rh plated products such as watches, cigarette lighters, decorative products, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing rhodium from an article having a rhodium surface obtained by plating, sputtering vacuum evaporation, etc., and particularly relates to a rhodium removal method using a 50-100% sulfuric acid bath.
It is specially designed to be forcibly removed by 100OH alternating current electrolysis (60 Hg is sufficient for 50 mm).

The purpose and main point of the present invention is to completely remove the rhodium-coated surface of products with rhodium surfaces, allowing the products to be recycled and reworked*! This method eliminates all methods for setting l'.

Conventional methods for peeling off rhodium coatings obtained by rhodium plating, two-batter vacuum evaporation, etc. have generally been impossible. When it is fully plated, it is chemically stable (chemically inert), has a very high hardness of Hr800-1000, and has excellent wear resistance.Rhodium itself is not attacked by ordinary acids or alkalis (VC at 300℃). (Although it is attacked by fuming sulfuric acid, iodine, sodium subzinc oxide, etc., it cannot be used as an industrial stripping method.) In addition, AC corrosion caused by concentrated hydrochloric acid and AC corrosion caused by 20% sulfuric acid cause corrosion of rhodium.
It does not have the ability to corrode the known plating coatings.

The present invention eliminates this drawback, and the present invention makes it possible to peel off the rhodium coating. As a result, it is now possible to completely remove the rhodium-coated surface of products with a rhodium surface and recycle the products.6.

The electrolytic stripping bath using this developed GFI has a nitric acid concentration of 50 to 100.
It is preferably about 70 to 90 inches. If it is less than 50 yen, the peeling speed is extremely slow and is not practical.

The electrolysis method is 1 to 1000 R17 AC (50 strata and 60
(Hg is sufficient), 20 or more F120 k/dm
"The above is desirable. The peeling time naturally depends on the thickness of the rhodium coating, but in the case of general rhodium plating, after 10 minutes of electricity, the black material adsorbed to the surface of the item (
Wash off the oxides of the underlying metal using ultrasonic waves and a brush brush #2, and then turn on the power again. It is best to repeat the method until the rhodium wrinkle coating is completely removed from the surface of the article.

The pass will be explained below through examples.

Example 1 A watch case made of brass (surface area 27α2) plated with xi + Pd - ni + Rh by a predetermined method was immersed in a stripping solution consisting of 700 c6/l of sulfuric acid, and both iK platinum jigs were removed. I used it to hang the case. Using ultrasonic waves, energize at AC 25 A/dm' for 10 minutes,
The black substance adsorbed on the surface was washed off by ultrasonic cleaning and the device was set again. When this one culm was repeated three times, the rhodium plating was completely peeled off. Goods Ni+ yi L p
Since it is protected by D plating, the watch case material did not get rough.

Example 2 Watch case made of nickel silver (surface area 11Crn2) VC
Ni + Ni -pd + R71 by a predetermined method
When the plated article was peeled off using the same peeling method as in Example 1, by repeating the peeling process twice, the plated surface was completely coated with KfIIllF. The watch case material H did not cause any rough skin.This method was explained in accordance with more than 60 examples, but this method relates to a method for removing rhodium from articles having a rhodium surface, 4(7)f,
$S, I! l1Vc50-100% nitric acid, preferably 7
It is characterized by forcibly peeling off by alternating current electrolysis using a 0% dihydric acid bath.

Using this method, the rhodium covering the surface of the product can be easily removed, and the product can be remanufactured or reworked without roughening the base metal.

This method can be applied to all decorative rhodium-plated products such as watches, lighters, and necklaces, so its industrial value is enormous.

that's all Applicant: Tenryu Industries Co., Ltd. Suwa Seikosha Co., Ltd. , 1' 5- Procedural amendment (voluntary) 1.Display of the incident 1981 Patent Application No. 1Q8729 2. Name of the invention Rhodium peeling method 3. Person who makes corrections Relationship to the case: Applicant Procedural amendment (voluntary) 1. The scope of claims is amended as shown in the attached sheet.

2. Specification: 3rd line to 2nd line from the bottom of page 1 [especially 5
1 to 1000 Hf AC electrolysis using a 0 to 100% sulfuric acid bath (at 50 or 60 Hf) is replaced with ``especially 1 to 1000 Hf using a 50 to 100v% sulfuric acid bath.
z AC electrolysis (corrected to 50 or 60H2fl).

5. Book 11, page 2, line 9 ``The size is Hr800J, “The size is also corrected to Hv800J.

4. Details v$5, line 2 to line 6 "50 to 100%, preferably about 70 to 90 inches. If it is more than 50%, the peeling speed is 7.4
Author t, <i<sui-11″・1°7=0゛～゛°°
.

"Hf alternating current (50 or 60 HY is sufficient)" is replaced by "50 to 100 V%, preferably about 70 to 90 V%. If it is less than 50 V%, the peeling speed is extremely slow and impractical. Electrolytic method is an alternating current of 1 to 1000 Hz (50
or 60Hz is sufficient).

5. Mei 11, page 4, lines 6 to 5 from the bottom, “Especially 5.
0-100% sulfuric acid, preferably using a 70% sulfuric acid bath.
The statement has been corrected to "particularly using 50-100v% sulfuric acid, preferably a 7QV% diluted acid bath."

The above-mentioned artist's top claims claim: An article having a rhodium-plated surface in a sulfuric acid bath (
After immersing the article in AC electrolysis and depositing black adsorbate (oxide of the underlying metal) uniformly on the surface of the article, it is rinsed off using ultrasonic waves, scraping, etc., and the rhodium coating is removed from the surface of the article. The above-mentioned steps are repeated until the rhodium is completely removed.

Claims (1)

[Claims] After immersing an article with a rhodium surface in a sulfuric acid bath with a concentration of 50 to 100% and performing AC electrolysis to uniformly deposit black adsorbate (oxide of the underlying metal) on the surface of the article, ultrasound,
Wash it off with a brush, etc. A rhodium removal method that involves repeating the above steps until the rhodium coating is completely removed from the surface of the article.