Copper plating is the process of applying a layer of copper to the surface of various metals (aluminum, steel, nickel, brass). Copper plating gives metals a visual appeal that can be used in a variety of design projects. Also, the copper layer is able to improve the electrical conductivity of metal products, which significantly increases the possibility of further surface treatment.
Any person who is at least a little familiar with the basics of chemical reactions can master the technology of aluminum copper plating at home.
History of the discovery of copper
Copper is the first metal that conquered man and played the greatest role in the history of the development of civilization. This event took place several millennia BC, and the exact date of the beginning of the use of this unique metal could not be established.
In ancient times, copper nuggets were mainly used to create weapons and household tools. Red-green nuggets of metal were initially used in the same way as ordinary stones. In the future, empirically, people noticed that the processing of this material with a hammer gives it special properties. This is how cold forging metal was born.
Even later it was discovered that the metal melts and after cooling it acquires other forms and properties. This stage was the initial in the development of hot forming of metals.
Characteristics and composition of copper
Copper is a rose-red heavy metal that is highly soft and melts at over 1080℃. The electrical conductivity of copper coating is 1.7 times higher than that of aluminum. Copper also has a high thermal conductivity.
Many specific properties of a metal are due to the presence of various impurities in its composition. So, according to oxygen, which is in the composition of copper, the metal is divided as follows:
- copper without oxygen contains less than 0.001% impurities;
- refined copper contains 0.001–0.01% oxygen;
- pure copper contains about 0.03–0.05% oxygen;
- General purpose copper has 0.05-0.08% oxygen.
The presence of lead or bismuth in copper reduces the plasticity properties of the material. Slightly soluble impurities (sulfur, lead, bismuth) increase the fragility of the metal.
In the process of electrolysis, in addition to oxygen, hydrogen can enter the composition of copper alloys.
Physical properties
The main quality of copper is low resistivity and, as a result, high electrical conductivity. An increase in various metal impurities in a copper alloy significantly reduces the electrical conductivity of the material.
The high thermal conductivity of pure copper is significantly reduced when a variety of alloying substances are added to its composition.
Also often used in the industry are copper products that are highly resistant to corrosion in various environments, except for organic acids, ammonia and ammonium s alts. An increase in the amount of impurities in the composition of copper leads to a significant decrease in the corrosion resistance of alloys.
Practical application of copper plating of metals
The procedure for copper plating of aluminum and other metals has a fairly wide practical application not only in domestic use, but also on an industrial scale. On many metals, a copper coating can be applied both as a main independent layer and as a sublayer for effective adhesion of the next main coating to the base metal of the product.
In most cases, copper plating of aluminum in home workshops is done for the following purposes:
- decorating jewelry;
- protection of metal parts from corrosion and carburization;
- elimination of damage and surface defects of products with complex shape and relief;
- production of copies of products made of various materials;
- creating pads for soldering aluminum without using an acid composition;
- preliminary surface preparation of parts before chrome plating,silver plating, nickel plating.
Types of copper plating of metal surface
The procedure for copper plating aluminum at home is not difficult to do on your own. It is not necessary to use special equipment and active chemicals. High-quality coating is ensured by strict adherence to aluminum copper plating technology and knowledge of ongoing processes.
There are two main types of copper plating for metal surfaces:
- With the immersion of the workpiece in the electrolyte, in which the product is partially or completely immersed in a bath with a chemical reagent. The use of this method is justified in the case when it is required to apply a layer of copper evenly over the entire product.
- Copper plating without immersing the part in a chemical solution. This method is more difficult to perform. Its use is very effective if it is required to make copper plating of a certain area of the product.
In both of these cases, the activation of the aluminum chemical copper plating agent is carried out electrically, which requires the use of a constant voltage source.
Dip Copper Equipment
For the high-quality performance of technological operations of aluminum copper plating, it is necessary to prepare simple equipment. Appropriate tools and materials can be either purchased from the distribution network or made independently.
To complete the work you will need the following materialsand fixtures:
- A 6-8 volt DC power supply with a smooth current adjustment device and an ammeter. If there is no adjustment, then it is desirable to include a rheostat and an ammeter in the circuit. They will be needed to control the process. If there is no stationary power supply, then a Krona-type battery can be used.
- Special bath made of a material that is not subject to electrolytic attack (glass, plastic). The dimensions of the container are selected in accordance with the dimensions of the workpiece.
- Copper electrodes, which serve to supply electric current to the electrolyte during copper plating of aluminum, and also make up for the loss of metal during the reaction.
- An electrolyte whose composition depends on the material of the original workpiece.
Preparation of copper plating solution
Finding a ready-made solution for aluminum copper plating in the distribution network is difficult. Usually, manufacturers allow the sale of the finished substance after presentation of the relevant documents. Therefore, most people make their own aluminum copper plating solution at home from copper sulfate.
For these purposes you will need:
- blue vitriol;
- distilled water;
- hydrochloric acid.
You can prepare a solution only if the recipe is followed correctly. To do this, copper sulfate (20 g) must be dissolved in 1 liter of water. Then add 2-3 ml of acid in a thin stream. The composition is thoroughly mixed until all crystals are completely dissolved.
The finished electrolyte for copper plating of aluminum with copper sulfate should be odorless and have a bright blue color.
Dip copper plating technology
Copper plating of aluminum metal by the method of complete immersion of the workpiece in the electrolyte is carried out according to the following technology:
- The surface of the workpiece is cleaned with sandpaper or a brush, then degreased in a hot soda solution and washed under running water.
- Two electrodes are suspended in the prepared container, which are connected to the positive terminal of the power source.
- A blank is placed between the electrodes, which is connected to the negative terminal of the power supply.
- The prepared electrolyte is poured into the working container. The solution level must be above the top of the electrodes.
- Using the adjustment device, the operating current value is set. The value of the parameter is based on the calculation of 10-15 mA per 1 cm2 of the area of the processed workpiece.
- After 20 minutes, the power is turned off and the workpiece is removed from the bath.
- Electrolyte residue is washed off with water and the part is dried.
The process execution time is approximate, it can be controlled visually by the color of the coating and the uniformity of its distribution. The longer the power is connected, the thicker the aluminum copper layer will be.
Dipless Copper Plating Tools
Copper plating worksmetal blanks without immersion in the electrolyte are carried out on large products that cannot be completely immersed in the bath. Also, this method is more efficient when processing individual parts of the product.
To perform technological operations for copper plating without immersion in electrolyte, the following devices will be needed:
- The chemical brush is made of stranded copper wire. For this purpose, you need to strip the insulation at one end of the wire, then separate the individual conductors a little. To make it convenient to hold the brush, it is better to tie it to a wooden stick or pencil.
- It is better to put the blank for work in any container without high sides. It is convenient to use an ordinary porcelain or glass plate. Additionally, you will need a container for the electrolyte, into which the brush will constantly be dipped. A glass can be used for this purpose.
- The power supply does not differ in parameters from the power supply used in immersion technology.
Dipless copper coating
The technology for performing work on aluminum copper plating without immersing the workpiece in the electrolyte is as follows:
- The brush, prepared in advance, is connected to the positive terminal of the power supply.
- Electrolyte solution, which is similar in formulation to the composition used in the part dipping case, is poured into the brush wetting container.
- Blank,previously cleaned and degreased, placed in an empty container. Using the connector, the part is connected to the minus of the power source.
- The brush is dipped into the electrolyte and driven over the place where the copper layer is to be applied. It is very important that the brush does not touch the surface of the part.
- After applying a layer of copper, the workpiece is washed under running water and dried.
In the process of doing the work, you need to make sure that there is always an electrolyte layer between the workpiece and the brush. To do this, the brush must be constantly dipped into a container with a solution.
Safety during work
All work with chemicals and the electrical source must be carried out with the necessary precautions.
Copper plating of aluminum in a residential area is strictly prohibited. For these purposes, it is better to use a utility room, garage or workshop. Electrical equipment must be grounded.
To protect human he alth, the following recommendations should be followed:
- respiratory protection must be used;
- so that chemicals do not get into the eyes, it is necessary to work in goggles;
- all work should be carried out in special clothing (rubber gloves, oilcloth apron, special shoes).
The process of coating aluminum products with a layer of copper is not particularly difficult even for a person who is little familiar with the course of chemical reactions. Buy ormaking the appropriate equipment will also not cause any special problems. But many products that seem to have lost their attractive appearance will acquire a second life.
