ELectroplated aluminium parts and process of production thereof

A component, multi-layer electroplating technology, used in the electroplating of currency blanks, electroplated aluminum parts, and coinage products

Inactive Publication Date: 2004-05-19
THE WESTAIM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although aluminum and its alloys have been used in coins, to the inventors' knowledge no pl

Method used

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  • ELectroplated aluminium parts and process of production thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0089] Embodiment 1 has the electroplating currency of copper plating layer

[0090] A 5052 gauge sheet of 4 feet, 8 feet long, and 0.0625 inches thick was purchased from a supplier and cut to 8 inches wide. The 8 inch strips were fed into a Minster PM3-125 punch press to produce cores for plating. The press adopts the picture A series of punches and dies arranged in a pattern to produce a round sheet called a billet. The billet had a diameter of 20.0 mm and a core thickness of 1.5 mm.

[0091]After the stamping operation, the blank is deburred and then edged with a standard EVD type coin beading machine. The machine operates automatically, where the billets are fed into grooved wheels using a vibrating feeder with controlled feed rate into a work zone that reduces the diameter of the billet and forms an edge on the billet. The edge height produced in the edge forming operation was about 1.70 mm. After blanking, deburring and edge formation, the blank is sent to pretreatm...

Embodiment 2

[0105] Embodiment 2 Improved copper electroplating bath

[0106] To obtain a "bright" electroplating bath, this example demonstrates the use of a two-step zincating, copper preplating, and copper electroplating bath. Example 1 was followed unless otherwise stated.

[0107] Edged aluminum blanks were prepared, followed by a zincating process similar to Example 1. After zincating, the blank was immersed in the low pH sodium cyanide preplating solution of Example 1, but with a pH of 9.0, 23 gpl of free cyanide and 30 gpl of copper. The zincate-treated blanks were immersed in the pre-plating bath for 15 minutes.

[0108] The next step is to electroplate the final copper plating on the blank using copper pre-plating. The copper concentration in the electroplating bath was 25.5 gpl. The free potassium cyanide concentration was 10.2 gpl. In addition, the bath contains 0.3% by volume of Atotech TM additive CL-3, and 0.5% Atotech additive CL-4. These additive brighteners were pu...

Embodiment 3

[0110] Example 3 Nickel-plated aluminum blank

[0111] This example demonstrates the method of the invention with a nickel-plated aluminum bill blank. Except for the final electroplating step, the similar blank preparation process is the same as in Example 1. After copper preplating, the blank is dipped into an electroplating bath of nickel sulfamate. The pH value of the nickel plating bath is 2.35, the concentration of boric acid is 42.2gpl, and the surface tension is 37.6 dynes / cm 2 , the nickel concentration is 113gpl.

[0112] The blanks were plated in a nickel sulfamate plating bath for 3 hours. The blanks were then rinsed in two separate rinsing steps, each for 2 minutes, followed by coinmaking in the same manner as in Example 1. The adhesion of the coating was checked with a 90° bend test. The plating cracks along the outside diameter of the bend, but cannot be stripped from the surface with sharp tools. Referring to Example 1, this demonstrates the strong adhesio...

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Abstract

The invention provides a pretreatment process for electroplating aluminum parts or strip, in which the zincating solution is modified to improve the adhesion of the subsequent electroplate to the substrate. The aluminum part or strip, such as an aluminum coin blank or strip for coin blanks, is pretreated with an improved zincate solution which provides hydroxide ions in an amount in the range of 75-175 gpl, zinc ions in an amount in the range of 15-40 gpl, nickel ions in an amount in the range of 2-10 gpl and copper ions in an amount in the range of 1.5-5 gpl. The pretreatment process preferably includes a copper strike applied from a copper cyanide strike bath at a pH in the range of 8.5-11.0, using a current density in the range of 0.1-10 A/dm2. The pretreatment and electroplating steps arc preferably conducted by barrel plating, in accordance with another aspect of the invention. The invention also provides electroplated aluminum parts or strip, such as electroplated coin blanks, including a substrate formed from aluminum or an aluminum alloy and having multiple surfaces, a layer of zincate on at least one of the surfaces of the substrate and preferably completely encasing the substrate, a strike layer of a strike metal covering the layer of zincate, and one or more electroplated layers of one or more metals covering the strike layer, said one or more electroplated layers adhering to the substrate to withstand a deformation process without delamination from the substrate.

Description

field of invention [0001] The present invention relates to a method of electroplating aluminum parts, including the electroplating of currency blanks. The invention also relates to plated aluminum parts, including coinage articles. Background of the invention [0002] The electroplating of aluminum and aluminum alloy substrates is more difficult than electroplating on many other materials, because when aluminum is exposed to air or water, a surface layer of oxide film is formed on aluminum immediately. This oxide film causes uneven deposition of plating and deteriorates the adhesion of the plating layer. Several methods exist for pretreating aluminum and aluminum alloy substrates to be electroplated. These methods include a) etching treatment, in which the substrate is pitted with a corrosive solution; b) anodization treatment, in which the oxide film is thickened by anodization and then roughened by etching; c) electroless plating Nickel treatment, where nickel is deposi...

Claims

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Application Information

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IPC IPC(8): C25D5/44
CPCC25D5/44Y10S428/935Y10T428/1275Y10T428/12736Y10T428/12243Y10T428/12792
Inventor L·C·莫林A·K·莫尔纳
Owner THE WESTAIM CORP
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