JPS6010115B2 - Black chrome plating method - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in black chrome plating methods.

Black chrome plating has traditionally been widely used for decorative purposes, and recently it has been applied particularly to car parts for fenders, opto-mechanical parts such as cameras, guns, fishing gear, and various equipment and accessories for Oyama Tobai. There is.

By the way, black chrome plating hardens over time after plating, but its hardness is low in the early stages after plating, so black chrome plating is applied to automobile exterior parts, various motorcycle equipment, and accessories. When assembling and installing items, if they hit other equipment or devices, they may get scratched and their decorative quality will deteriorate.

In addition, black chrome plating is used for decorative plating because there is a small amount of powder on the surface, so it does not make any noise, so after plating, you can apply transparent lacquer or oil to achieve a uniform luster and shine. Because it produces oil, when the oil runs out, the luster and luster deteriorate. Furthermore, black chrome plating discolors due to heat, so for example, the blackness of black chrome plating applied to various equipment near the engine of a motorcycle deteriorates due to the heat transferred from the engine, and its heat resistance decreases, making it less effective as a decoration. is lost. The present invention has been made to eliminate such drawbacks, and it increases the initial hardness after black chrome plating to prevent scratches, and also achieves blackness and gloss without applying transparent lacquer or wiping with oil. The object of the present invention is to provide a method for plating black chrome that can produce a rich black color that changes color due to heat.

The black chrome plating method of the present invention involves applying any one of nickel plating, copper nickel plating, copper nickel chrome plating, nickel chrome plating, etc. to the object to be plated as a base, and then applying black chrome plating. , 0.001 to 1 on top of that
．． It is characterized by a glossy chrome plating with a thickness of 0 french.

When nickel plating is applied as a base, two-layer nickel plating or three-layer nickel plating may be used. In the black chrome plating method of the present invention, the first reason for applying glossy chrome plating of 0.001 to 1.0 mm on top of the black chrome plating is that This is to form a protective film to increase hardness, give a black gloss, and suppress discoloration due to heat. If the thickness is less than 0.001r, hardness and coverage of the entire part will be insufficient, and discoloration due to heat. It is difficult to suppress this, and if the temperature exceeds 1.0r, the black color will be lost and it will be difficult to say that it is black chrome plating.

The second point is that the thickness of the glossy chrome plating after black chrome plating is 0.0M to 1. By arbitrarily controlling the Q finish within the range, it is possible to obtain a blackish silver plating that cannot be obtained by conventional plating methods. A comparison between a specific example of the black chrome plating method according to the present invention and a conventional example will be described below.

[Example] After polishing the outer surface of the part connected to the motorcycle engine, which is the object to be plated, degreasing, acid washing, and neutralizing.
After activation and pre-treatment such as washing with water, nickel plating is applied as a base (rich composition: nickel sulfate 300 times a day; nickel chloride 50 times a day, boric acid 45 times a day; operating conditions: 3.5 to 4 days. 5. Temperature 55℃, current density 4A nod force,
Voltage 4 to 7 V) was applied for 20 hours, and then black chrome plating was applied on top (bath composition: chromic anhydride 300 hours/day, 9 days hydrogen silicofluoride, 1 day potassium nitrate 3 hours/evening, operating conditions temperature 1000, current density 40 A). /d phosphorus, anode lead-tin alloy, voltage 5V), and then bright chrome plating (
Composition: chromic anhydride 250 tanom, sulfuric acid 2.59/meth, trivalent chromium 3 tanom, liquid temperature 5 pu0, current density 4 ships/
d) was applied 0.02 times.

[Conventional example]

After polishing the outer surface of the parts connected to the motorcycle engine, pre-treatments such as degreasing, pickling, neutralizing and activating, and washing with water are carried out. 20 coats of nickel plating were applied, followed by 2 coats of black chrome plating with the same bath composition under the same operating conditions as in the example.

However, after inspecting the appearance of the plating for each of the 10 parts connected to the engine of the example and the conventional example, it was found that the black chrome plating of the example had the intended blackish tone. In contrast to conventional black chrome plating, which has a black tinge, there is fine powder attached to the surface.If it is not oily, there will be less koji and the surface will be dull. It was.

In addition, a comparative test was conducted on wear resistance (P) and discoloration due to heating on each of the parts connected to the engine of the example and the conventional example, and the results shown in the table below were obtained.

As is clear from the table above, the black chrome plating of the example is ``more abrasion resistant and stable with less variation than the conventional black chrome plating,'' and has less discoloration and better heat resistance. It turns out to be excellent.

In contrast to the details described above, by using the black chrome plating method of the present invention, black chrome plating with high initial hardness after plating can be applied to a plated object. It won't get scratched even if you touch it with other parts when installing or installing it.Also, this black chrome plating is smooth and has a black tinge and gloss, so there is no need to apply transparent lacquer or oil. Furthermore, this black chrome plating has excellent heat resistance as it is less likely to change color due to heat.

Claims (1)

[Claims] 1. Apply any of the following to the plated object as a base: nickel plating, copper nickel plating, copper nickel chrome plating, nickel chrome plating, etc., and then apply black chrome plating,
A black chrome plating method characterized by applying glossy chrome plating with a thickness of 0.001 to 1.0 μm thereon.