Copper coatings are not recommended for protecting iron and steel from corrosion. Copper-plated products can only be protected from atmospheric corrosion! in the case when copper coatings are completely free from pores of even microscopic size. If there are pores, the products will not only not be protected from corrosion, but, on the contrary, in the presence of a corrosive agent, a short-circuited galvanic cell will begin to work between iron and copper, in which the iron will play the role of an anode and its corrosion will proceed more intensely than non-copper-bonded iron .
Copper coatings cannot also be considered as protective and decorative. Although the chemical resistance of copper is greater than that of iron, in an external atmosphere with low relative humidity, copper coatings become dull as a result of oxidation, which proceeds according to a parabolic law. With increased humidity in the pores of copper coatings, rusting of the steel (anode) occurs. On non-porous copper coatings in an outdoor atmosphere with high humidity a green patina gradually forms, which, according to some sources, is basic copper sulfate CuSO 4 3Cu(OH) 2; Basic copper chloride may form on the sea coast. The stability of the patina in different atmospheres is apparently due to the formation of cuprous oxide. By anodic oxidation in appropriate electrolytes, a patina can be artificially obtained.
The process of copper plating of sections of steel parts that are subject to cutting after heat treatment - carburization - is quite widespread. Steel parts are sometimes copper-plated, followed by chemical or electrochemical painting. various colors. However, copper coatings are most widely used as intermediate layers for protective and decorative chrome plating of steel and zinc parts. The widespread use of electrolytic copper deposits as intermediate layers when applying various galvanic coatings is to a certain extent determined by the good adhesion of electrodeposited copper to various metals. Unlike hot application methods metal coatings, in which an intermediate diffusion layer is formed between the base metal and the coating, during electrolytic deposition of copper on steel it is not possible to detect an intermediate diffusion layer. Decisive role to ensure strong adhesion in in this case Careful preparation of the surface of the base metal plays a role - degreasing and etching, and in the case of chemical or electrochemical removal of the deformed layer, continuation of the structure of the base metal in the electrodeposited metal is often observed. The adhesion strength between the base metal and the coating in this case approaches the strength of the bond between individual atoms in the solid metal.
The continuation of the microstructure of the base metal in the electrolytic deposit is apparently ensured in cases where the base metal has a relatively coarse-crystalline structure and electrolysis proceeds under conditions corresponding to the formation of crystals of approximately the same size. When foreign ions, atoms or molecules are included, the deposits become finely crystalline and no continuation of the structure of the base metal is observed (Fig. 82).
Rice. 82. Continuation of the structure of the base metal of electrodeposited copper (from bottom to top): silver (a), nickel (b) (no continuation), c - rolled copper
During protective and decorative chrome plating of steel and zinc parts, the role of the copper layer is reduced to maximum savings of strategic nickel while maintaining the protective properties of the total coatings (Cu+Ni+Cr) and reducing the labor intensity of mechanical preparation of the surface of steel parts.
As you know, copper is much more ductile than steel, and in the process of polishing it, it is possible to obtain a smooth, shiny surface, onto which it is easy to apply shiny nickel coatings. Here it is necessary to stipulate that great progress has recently been made in obtaining shiny coatings that do not require polishing, but this problem has not yet been completely solved. By applying relatively thin layers of cyanide or pyrophosphate electrolytes to steel or zinc parts, shiny or semi-shiny copper coatings can be obtained, over which, after washing, bright nickel coatings can be applied.
In this interesting video tutorial, we will look at how you can make a solution that will act as an electrolyte for copper plating of any metal objects, for example, aluminum using a toilet duck.
What is needed for the process.
For this we need plastic bottle with water, copper wire without insulation. It is advisable to use a wire with a minimum cross-section so that the reaction area is as large as possible. If there is no copper wire, coins containing copper are suitable. yellow color. Instead of wire or coins, you can use absolutely any copper shavings, scraps, or waste that contains copper. You also need to add a small piece of tin.
The object for copper plating in this video tutorial will be a steel knife handle. In addition to toilet duck, another cleaning product that contains hydrochloric acid, which reacts with copper and dissolves it, may be suitable.
Let's prepare the solution composition for copper plating.
So first let's do the following. The contents of the toilet duck must be poured into a bottle of water to obtain a solution in which the copper will be immersed. Now we put a copper wire and a piece of tin into the solution. After this, this solution must be left, preferably in a warm place, for as long as possible. long term. The concentration of hydrochloric acid contained in the loss requires keeping the jar to dissolve the copper for one month. That's the entire composition of the solution.
Processing a workpiece for copper coating.
Preferably metal blank clean from rust and dirt by boiling in an alkali solution or, at worst, with regular sandpaper.
When cleaning and grinding is completed, it is necessary to degrease the workpiece, since human fingers contain fat.
Before using the copper plating solution, it must be shaken well so that the copper salts are mixed with the liquid. Now you can place the workpiece in the copper plating solution. It is advisable to occasionally shake the container with the electrolyte during copper plating and turn the workpiece over to create an influx of fresh solution to it.
An hour and a half has already passed, you can see how the process went. It is clearly visible that the workpiece is coated with copper. It must be washed with water. Copper adheres to it very well. It turned out very nicely, but it is better not to cover the handle of the knife with copper, as it tends to oxidize and, accordingly, stain your hand. you can do and not only this.
The surface treatment of various objects is carried out to give decorative effect or as an intermediate procedure preceding further actions. Many processes are easy to implement and do not require a lot of equipment. One of the most popular processing methods is copper plating, which can also be done at home.
What is the copper plating process?
Copper plating is the process of applying a thin layer of copper to the surface of an object. It is performed by the galvanic method, that is, by transferring copper ions from a positively charged source to a negatively charged surface to be treated. Most often, the process of electroplating copper is a preparatory step before plating with nickel and chromium, but often copper plating of metal becomes an independent species finishing. Electroplating, which requires the creation of a copper coating, is widely used.
Types of copper plating
There are two options for copper plating at home:
- With immersion of the workpiece in electrolyte.
- No immersion.
With immersion of the workpiece in electrolyte. To perform the procedure, you must have a container with electrolyte of sufficient volume. After preliminary preparation consisting of cleaning the surface sandpaper and rinsing in a hot soda solution, the object is connected to the negative electrode and immersed in the electrolyte for a certain time.
No immersion. Can process steel, aluminum, lead, zinc. Processing is carried out without immersion in a container; this option is usually used for large parts.
Both options are quite accessible for self-execution at home.
Equipment and materials required for copper plating
To carry out copper plating of steel or other metals, you will have to stock up on some materials and devices. You will need:
- Copper sulfate (copper sulfate).
- Source direct current, preferably with an adjustable voltage (one of the options is LATR), but a regular 6–12 V transformer will do.
- Container for electrolyte (optimally a glass reservoir).
- Two copper plates that can fit freely into the container.
Of water, copper sulfate and hydrochloric acid it is necessary to make an electrolyte. First, copper sulfate is added to the water until a saturated solution is obtained. It must be thoroughly mixed so that no solid particles remain. Then hydrochloric acid is added to the solution in a thin stream (not vice versa!). In total, to apply the coating you will need:
- - 980 g.
- - 190 g.
- - 40 g.
Now everything is ready, you can start copper plating at home.
Attention! It is necessary to take into account that hydrochloric acid is a chemically active reagent, so you should stock up on protective equipment - gloves, goggles, and prepare the workplace as much as possible.
Copper plating technology
Procedure for applying the coating:
- It is necessary to remove a thin film of oxides from the surface of the part to be processed. Sandpaper, wire brush or other abrasive materials are used. It is necessary to act very carefully, since severe damage to the metal will remain noticeable. Ideally, the surface should be polished.
- Then the product is thoroughly washed in a hot solution of soda ash. This action allows you to degrease the surface.
- The prepared product is connected to the negative electrode from the power source and placed in an electrolyte solution.
- Copper plates with a positive electrode from the power source (anode) attached to them are lowered into the electrolyte solution. It is necessary to ensure that the anode and cathode do not touch. Ideally, the distance between them should be the same in all areas, but in practice this is difficult to achieve.
- Copper plating of metal is carried out in several stages. It is recommended to remove the first layer of coating, obtained within a few minutes, and rinse the part again in a soda solution. This will strengthen the adhesion of the copper plating layer to the base metal. The part is kept in the solution for about 20–30 minutes. The thickness of the coating layer can reach 300 microns.
It is often necessary to remove the coating layer from chrome parts. To do this, a negative charge is applied to the part, and a cloth soaked in a solution of sulfuric acid (5%) is wrapped around the positive electrode. The surface of the part is wiped with it, the chrome plating layer is removed. When performing the procedure, it is necessary to protect the skin, vision and respiratory organs from acid vapors.
Copper plating of parts without immersion in solution
Galvanic copper plating can be performed without immersing the part in a container with electrolyte. To do this, you need to connect a negative electrode to it. A stranded copper wire is taken as a positive contact, the end of which is removed from the insulation by 1–2 cm and kneaded so that it looks like a brush.
To apply a layer of copper coating, the “brush” is dipped in electrolyte, then its end is passed along the surface of the part, without touching it, but trying to ensure that there is a layer between them. Constantly dipping the anode into the electrolyte, cover the entire surface with a layer of copper. The procedure requires skill and time, but the result is worth it.
Electrotype
Copper plating can be done not only on metal objects. Electroplating is widespread, when copper plating is performed on various dried plants, insects and other non-metallic objects.
The coating technology differs little from the usual one, only at the beginning of the process it is necessary to apply an electrically conductive varnish to the surface. After drying varnish coating The usual steps are taken to apply a layer of copper. The resulting products have high decorative or artistic qualities and are highly appreciated by viewers.
In this instruction I will tell you how in a few simple steps cover the metal washer with copper. You will have a wide field for experimentation: you can change the time, voltage and composition of acids. I will only go through the basic steps of electrolytic copper plating, explaining the “how to do it”, but not going into detail about “why it happens.”
Briefly about the experiment at home: its price varies between 50-150 rubles, the experiment will take you 1 - 3 hours, and its complexity, depending on your electroplating skills, varies from easy to medium.
Carefully! Conduct the copper plating experiment in a well-ventilated area, and if you are young, ask an adult to help you.
What you will need:
- Copper - 2 small pieces (in the video I use copper wire, but in principle any copper object will do)
- A metal object that we will coat with copper (I took a washer)
- Glass container with lid
- Alligator Clip Wires x2
- Power supply (preferably regulated voltage)
- Vinegar (which will act as an acid)
- Polishing tool (if you want to polish the object after copper plating)
I recorded a video for this instruction. In it I went through all the steps of copper plating, which are described below.
Step 2: Dissolve the Copper
I'm not sure if "dissolve" is the right word, but it explains exactly what we'll be doing in this step. Start by clamping the copper object with alligators. Then place the object into the container. Check that the crocodiles are not touching. Add vinegar to the container until most of the copper object is covered, but do not allow the crocodiles to come into contact with the vinegar (see photos).
Now it's time to connect the alligator wires to the power source. Do not plug in the power source yet. When both alligator wires are connected to the power supply, set the voltage to 12V. After this, you can connect the unit to the network.
(In the video you can see that the power supply plug is cut off to make it easier to connect crocodile clips).
You will notice that one part of the copper wire is covered in bubbles. Remember this part, it is negative.
I let the whole setup run for about 30 minutes, but you can try playing with the voltage and timing. For safety reasons I recommend you stay in the 0-12V range as everything works very well at these settings.
Step 3: Copper Plating
After 30 minutes I unplugged the power supply and disconnected the negative crocodile (on the side of the copper that was bubbling). Then I connected a metal object (in my case a washer) to this crocodile. Set the power supply voltage to the lowest possible (to start with). My unit's minimum is 3V. Connect the unit to the network again and watch how the metal object is coated with copper. I let my puck sit in the solution for about 30 minutes.
There is an opinion that after the procedure you need to dry the product for 1-2 days. I don't know if this is true or not, but I didn't notice any difference when removing excess material from the washer whether it sat for 2 days or 30 minutes.
To make an item shine, you just need to polish it (using the appropriate tools and materials), but do not overdo it, as the coated item only contains thin layer copper
Be sure to experiment with exposure time and voltage to achieve different results and try to achieve as uniform a copper coating as possible.
IN modern world Copper alloy has become more widespread. It is applied to the surface to give visual appeal to various products. Copper plating at home is often carried out to significantly increase electrical conductivity. In some cases, the process in question is an intermediate operation that allows another substance to be applied to the surface.
Use of copper plating
Copper plating of various workpieces has recently often been carried out at home. In most cases, technology is used to achieve the following goals:
- Decorating metal or plastic. Copper plating of metal at home is often carried out in order to obtain antique-looking products that are very popular. A special aging procedure allows you to create the effect of long-term use of the product. In addition, copper after application resembles gold. That is why a small layer can be applied to obtain a figurine or souvenir.
- Electrotype. Copper plating of steel in a similar way can also be carried out at home. The essence of the technology is to create a wax or plastic base, which is covered with a layer of the alloy in question. Electroforming is often used to produce jewelry or souvenirs, matrices and waveguides. The use of special materials can significantly improve the quality of the coating.
- Obtaining parts used to create various mechanisms. Copper plating of cast iron or other metal is carried out at production sites at various technologies. Coating the workpiece with copper can significantly improve the electrical properties. In a similar way, you can obtain terminals or other similar elements that will be operated under voltage. Products made from pure copper are very expensive. That is why the technology in question is often used.
Copper plating of plastic at home is carried out extremely rarely, since such material does not withstand exposure high temperature. In addition, the plasticity of the base leads to the appearance of structural cracks.
Features of copper plating at home
Copper plating of metal is a special technology for applying a layer of copper with a thickness of 1-300 microns or more. The features of the technologies used determine that the copper coating will adhere firmly to the metal surface. Among the features that the workpiece acquires, we note the following points:
- Plastic.
- High electrical conductivity. Copper products are well known for being able to conduct electricity without getting hot. That is why products are often created that are coated with a similar alloy.
- More attractive look. Copper glitters in the sun, reflections appear on the surface.
- Under atmospheric conditions, the alloy easily oxidizes and becomes coated. This point should be taken into account when considering where and how exactly the product will be used.
- Over time, copper film becomes covered with spots and rainbow stains.
Copper plating at home can be carried out using a special solution. It is worth considering that the process involves the use of special reagents. Therefore, it is necessary to provide for the availability of effective supply ventilation, and individual funds protection. Copper plating of plastic is somewhat different and involves the use of special technology.
Types of copper plating
The procedure in question can be performed even by beginners in the field of metallurgy. To obtain a high-quality surface, you need to know all the features of the process. Copper plating of lead and other metals at home can be carried out using two different technologies:
- Immersed in electrolyte. This technology involves dipping the workpiece into a prepared solution, after which voltage is applied. It is often used when the workpiece is small in size, since a smaller amount of special electrolyte is required. To immerse the workpiece, a bath or other container is required that does not react to the effects of the solution used.
- Without immersion in a pre-prepared container. It is difficult to implement, but also allows you to achieve high quality copper surface film.
In both cases, a supply of electricity is provided, due to which the substance is activated.
Most suitable way processing is selected depending on the result to be achieved. Let's take an example:
- Obtaining a protective and decorative layer. In this case, chromium is often mixed with nickel and copper. Due to this combination of alloys, a reliable surface can be obtained.
- To protect the surface during cementing. Applying a thin layer of copper helps protect the workpiece from cementation. The surface that will be subsequently processed by cutting is covered with the solution.
- Restoration and repair of parts. When restoring chrome parts of cars and motorcycles, the technology in question can be used. When applying a layer of no more than 250 microns, surface defects in the metal can be hidden.
Both processing technologies have their own specific characteristics that must be taken into account.
Copper plating in solution with electrolyte
Electroplating Copper testing at home with immersion is carried out extremely often. This technology allows you to obtain a uniform coating. The features of this processing method include the following points:
- To remove the oxide film before copper plating, the workpiece is treated with sandpaper. After this, the product is washed and degreased with a hot soda mixture. If you don't pay attention preparatory stage, then the process being carried out will not allow obtaining a product resistant to mechanical stress. Metal that is susceptible to corrosion must be well cleaned, since even small chips can make the surface uneven.
- Two plates of the same alloy are lowered into a jar or other container on copper wires. They act as an anode. The container used must be made of glass.
- The workpiece is suspended between two anodes, which is connected to the minus, and the plates to the plus. A battery producing a voltage of 6V can be used as a power source.
- Galvanic copper plating involves the use of a specific solution. It is the connecting element between the part and the anodes. A solution for galvanic copper plating can be prepared by taking 20 grams of copper sulfate and 3 milliliters of sulfuric acid. To dilute and mix these ingredients, you can use 100 milliliters of distilled water. When working with the resulting solution, you need to be extremely careful, since if the substance gets on open areas skin burns may occur.
- Copper plating of aluminum with copper sulfate at home can only be carried out if the electrodes are completely covered with the solution. If they are kept dry, they may heat up and melt. During prolonged processing, the substance may heat up and its volume will decrease.
When using the technology under consideration, the current is set at 15 mA per square centimeter. It usually takes at least 20 minutes to cover the entire surface with a special alloy. As the period increases, the coating becomes thicker.
Copper plating without immersion in solution
A similar method is used to coat steel, zinc or aluminum. Coating a product with copper at home in this case is carried out with a wire, from which the insulation is first removed to obtain a kind of brush. The opposite end of the wire is connected to the positive energy source. Chemical copper plating at home also involves the use of a special solution, which increases the efficiency of the process.
Among the features of creating the required solution, the following points can be noted:
- A solution of copper sulfate is used. It can be purchased in specialized stores. In addition, a special electrolyte is made by mixing various chemical elements.
- The composition is slightly acidified. Due to this, the efficiency of the procedure is significantly increased.
The substance is applied to the surface, after which it is prepared metal surface. It is cleaned of contaminants and then degreased. After this, the plate prepared in advance is placed in the bath and a minus voltage from the current source is supplied to it.
This process requires that there is always a layer of electrolyte between the assembled wires and the plate. This ensures a high degree of conductivity. To cover the product small sizes it only takes a few seconds.
After coating, the product is air dried. Various pollutants must not be allowed to enter. The next step is to rub the copper layer with a woolen rag or other cloth. In most cases, the technology in question is used when the product has big sizes and cannot immerse himself in the bath.
Necessary equipment
Copper plating can be applied at home using even the most ordinary equipment. Installation of a bathtub for the procedure under consideration is carried out in approximately the same way as galvanic ones. It is worth considering that there are two types of active solutions: acidic and alkaline.
When working it can be used:
- Small copper plates as electrodes.
- Wire for supplying current.
- A current source, for example, a battery, which is designed to supply a current of 6 V.
- A rheostat can be installed to regulate the current.
Copper plating of aluminum and other alloys at home does not require much time. Various fabrics can be used to clean the resulting surface.
