In 1840, a Russian physicist of German origin, Moritz Hermann, who, after moving to Russian empire changed his name and surname to Boris Jacobi, writes a work with a long title: "A method of producing, according to the samples, copper products from copper solutions using electricity or electroplating for applied arts." The history of electroplating begins with this scientific work not only in Russia, but also in the world.
In his research, Jacobi relied on more early work Italian physicist Luigi Galvani, and therefore called the process galvanoplasty, and the container in which this miracle takes place is a galvanic bath.
Currently, electroplating is a branch of electrochemistry and studies the deposition of electrolytes on the surface of metals. On the other hand, electroplating divided into two major subdivisions:
- Galvanoplasty: an electrochemical method of copying. With its help, a sufficiently thick layer of metal is applied and, as a result, an exact copy of the copied object is obtained. In particular, vinyl records and laser CDs are made using this method.
- Electroplating: An electrochemical technique for coating a substrate with a layer of metal in order to obtain a stronger or more decorative layer. Often these two tasks are combined.
Through the electroplating process, it is possible to cover with a layer of metal, to chrome almost any surface: metal, plastic, wood, leather. Chrome-plated boots or nickel-plated boots are a very real thing, but not quite practical. The coating of one metal with another is much more in demand in order to increase the anti-corrosion, strength and aesthetic characteristics. Processes such as chromium plating, nickel plating, copper plating, zinc plating have long been a common practice in large-scale industrial production.
Do-it-yourself chemical metallization at home. Electroplating at home is a very real thing, of course, subject to certain requirements. Of all the types of home electroplating, chrome plating is perhaps the most difficult type of electroplating. for two reasons:
- The technical complexity of the process.
- The extreme danger of chemical components for health.
First technical difficulty
The complexity of chromium plating lies in the fact that very stringent requirements are imposed on the mode of operation of the galvanic bath. The slightest deviations from the required current density, temperature and electrolyte concentration lead to a sharp change in the quality of the chromium coating, up to marriage.
The ability of chromium to change greatly in terms of quality, depending on the electrolyte temperature and current strength, is actively used in production to obtain chromium coatings with varying degrees of gloss, color and strength.
- At an electrolyte temperature of 30–60 degrees, the surface finished product will be shiny.
- Above 60 degrees - the chrome coating will have a milky tint.
- Below 30 degrees - the surface is matte.
From the concentration of the composition of the electrolyte, chromium changes color, and along with the color, strength characteristics also change. The color changes from the usual light, to dark blue, agate, blue, and finally to almost black. As the color changes, so does the strength of the chrome plating. The softest chrome has a normal light color and requires room temperature and current strength of the order of 5 A / sq. dm. The most durable chrome finish corresponds to black chrome. But to obtain black chrome, a current of 100 A / sq. dm is required, which is technically impossible to do in home production.
Second technical difficulty
The second difficulty is that chromium cannot bond directly to steel, aluminium, cast iron or iron. Therefore, nickel plating is always carried out before chromium plating. Often, in order to obtain a better result, several consecutive layers are applied: nickel, copper, again nickel, and only at the end a layer of chromium is applied.
It should be borne in mind that the chromium coating itself has enough contradictory characteristics. On the one hand, chromium has a high mechanical strength(much higher than nickel), chemical inertness and very bright luster. But at the same time, it is very fragile and has a porous structure. Therefore, a nickel substrate for the chromium layer is necessary even if chromium plating is carried out on the surface of a metal with which chromium adheres well, such as copper or brass.
Thus, the process of chromium plating at home automatically involves at least two consecutive technological processes: nickel plating and chromium plating.
health hazard
The main component of the electrolyte for chromium plating is chromium oxide (CrO3) or, as it is also called, chromic anhydride. It just so happened that chromic anhydride is the strongest poison and at the same time one of the most powerful carcinogens. The lethal dose for humans when taken orally is approximately 4-6 grams, depending on the weight of the individual. When pure chromium oxide or its solutions come into contact with open areas of the skin, chemical burns occur, which then turn into dermatitis and eczema, followed by degeneration into skin cancer.
When chromium oxide is combined with substances of an organic nature, such as technical solvents, gasoline, kerosene, instantaneous ignition and explosion occurs.
It is clear that such a “beautiful” chemical substance cannot simply be taken and bought in a chemical store. reagents. The turnover of chromic anhydride is strictly regulated by the state and the sale is allowed only legal entities who have a license for the relevant type of activity.
Necessary equipment
Chrome plating in the kitchen of a residential apartment can only be carried out by a potential suicide. In order to start the process of chrome headlight plating, it is necessary to have a special room for this, as far as possible from residential buildings. A spacious workshop or garage is best suited for these purposes. Must have a good forced ventilation. Previously, all containers with gasoline, paints, varnishes and other solvents must be removed from the room. It is mandatory to purchase a good fire extinguisher and work out the option of an emergency exit from the premises in case of an emergency.
For chrome plating, you must have:
- Galvanic bath. Either glass or durable plastic that can withstand temperatures up to 100 degrees.
- Rectifier. Source direct current with adjustable output voltage. Parameters - 12V / 50A. If we are talking about small details, then you can use Charger for car battery.
- Heater. Must withstand long-term exposure to aggressive acidic environments. For example, ceramic heater. A regular tenon will not work.
- Thermometer. With divisions from 0 to 100 degrees. Optimum temperature for the process is 45−55 degrees.
It must be borne in mind that in order to optimize the process, it is necessary to equip at least two such installations, one for chrome plating and the other for nickel plating. Otherwise, you will have to constantly change the reagents in one container, which is extremely inconvenient and costly.
Three components of the electroplating process
Electroplating at home, chrome plating is a galvanic process. Therefore, in order to carry it out three components are required: cathode, anode and electrolytic medium in which the transfer of charged metal particles will occur.
- Cathode. A plate of pure lead or an alloy of lead and tin. It must be remembered that the area of the cathode must be greater than the area of the anode. The cathode is connected to the positive output of the rectifier.
- Anode. This is the chrome part itself. It must hang in the electrolyte environment in such a way that it does not touch the walls and bottom of the container. In addition, the anode must never touch the cathode.
- Electrolyte. Chrome plating requires particularly careful preparation of the electrolyte.
Electrolyte preparation
In a set of electrolytic liquid for chrome plating includes the following components:
- Chromic anhydride: 250 gr/l.
- Sulfuric acid: 2-3 g/l. Chemically pure, concentrated. Technical sulfuric acid is not suitable.
- Distilled water.
Water is heated to a temperature of 60−80 degrees. After that, the anhydride dissolves in it. The solution is slightly cooled and then a thin stream is added to it. required amount sulfuric acid.
Preparation of the surface of the chrome-plated product
Consists of three stages:
- Mechanical cleaning, grinding and polishing.
- Degreasing.
- Nickel plating.
A feature of chrome plating is that it, on the contrary, emphasizes all the existing bumps, chips and cracks on the surface of the product. Therefore, traces must first be removed from the surface of the chrome-plated part. old paint, rust, chips, cracks and other defects. Preparing the chromed surface with consists of the following steps:
- Sandblasting.
- Polished with fine sandpaper.
- Grinding soft materials and polishing paste.
Do not use gasoline or white spirit for degreasing. Otherwise, there will be problems with the quality of chrome plating. The best option — prepare a special solution:
- Caustic soda: 150 gr/l;
- Soda ash: 50 g/l;
- Glue silicate: 5 gr/l.
The solution is heated to 90 degrees. After that, the part is lowered into it and kept for 20-40 minutes, depending on the area and topography of the surface of the part.
Nickel plating is last step preparation of the part for chrome plating. The nickel plating process is carried out in a special electroplating bath. In this case, metallic nickel is the cathode, and a solution of sulfuric acid and nickel salts acts as an electrolyte.
Stages of chrome plating
Direct chrome plating consists of a number of successive steps:
- The process begins with raising the temperature of the electrolyte in the bath to 50-54 degrees.
- A chrome-plated part is placed with a preliminary connection to it of the cathode outlet.
- After that, they stand for some time without applying voltage to the system. During this time, the temperature of the part and the electrolyte should equalize.
- After applying voltage, the workpiece is in the solution for at least 20 minutes. In some cases, chrome plating can last 2-3 hours. Everything is decided on an individual basis, depending on the size of the part and the desired final characteristics of the chrome plating.
- After the end of the process, the part is removed from the solution, washed and placed in drying cabinet for 2-3 hours.
There are a lot of video tutorials on electroplating on the Internet, in particular, on chromium plating of metals. Therefore, all the details of this process can be gleaned there.
Quite often, many craftsmen want to protect some part of a car or motorcycle from corrosion. You can of course do this with a primer and paint. Well, what should the master do if, for example, the seat for the bearing in the crankcase of the engine or gearbox has become loose (worked out) and turns it. How to restore a worn surface and increase its size (diameter)? Paint won't help here.
Everything seems to be quite simple. It is necessary to increase the surface of the part in a galvanic way, that is, by applying a thin layer of some kind of metal, and if you apply several thin layers, you can restore a rather deep wear of the surface of the base metal. For coverage metal surface chromium or nickel, sophisticated factory equipment, as well as a bunch of exhaust and ventilation systems, since the imposition of these shiny metals is very unhealthy.
I propose a much simpler method, which can be done even at home in the kitchen, and besides, it is harmless. Although this method is not as shiny as nickel or chrome, it allows you to perform two important functions. This is the protection against corrosion of the steel part and the restoration of its size (if it is worn out). Anyone can use this method, even a chemistry student.
To implement this coating method, you need to buy a little ordinary electrolyte for batteries in a car shop. Then you need to collect some metal, which will be electroplated. This metal is resistant to corrosion and is very common - it is zinc. Where to get it? Yes, everywhere. Remember how many batteries you and your friends have spent and lying around anywhere. Collect them, and moreover older than a year release of the battery, the better zinc they have and the easier it is to remove it. Using a sharp knife, score the battery case and carefully peel off the zinc like a tangerine peel, then rinse the scraps with water.
Now you can start on your own chemical process. Pour 100-150 grams of electrolyte into a glass or porcelain jar, and then slowly (so that the reaction does not go too violently) pour zinc trimmings into it. You'll see what starts right there chemical reaction, and as a result of this, a solution of zinc sulfate is formed, which you will need, as well as an explosive gas consisting of hydrogen and oxygen. The same gas is released when charging a battery and it is very explosive, so work away from open flames and drive smokers away. If someone is too lazy to mess with the electrolyte, then you can look for ready-made zinc sulfate in chemical stores.
When adding pieces of zinc to the electrolyte, it will dissolve, and zinc will need to be added until it stops reacting with the acid (stops dissolving), that is, the acid is consumed in the reaction completely and completely “saturated” with zinc. Also, you should prepare for coating the metal parts that you are going to cover with zinc. Clean them from dirt and rust, and if the part is decorative, then it is advisable to polish it to a shine, because any electroplated coating exactly repeats the surface relief of the metal being coated. And if there are scratches on the surface, then after coating, no matter what, even with chrome or nickel, all these scratches will be visible on the surface even better.
By the way, all rust can be removed from the metal surface not mechanically, but chemically. To do this, lower the rusty part into the battery electrolyte, hydrochloric acid, or even ordinary vinegar. But in no case not in a rust converter, as local experts can advise, since zinc, and chromium, too, will never stick to the phosphate film formed from the converter. A rust converter should only be used when you just want to prime and paint a part.
Let's continue work. Pour the prepared zinc sulfate solution into a glass or porcelain vessel, the size of which depends on the size of the part that you are going to cover with zinc. But if you have problems with glass or porcelain, then you can use a suitable trough cut from a nylon canister.
The power supply is best used with current regulation (variable resistor) and an ammeter, looking at which it is convenient to adjust the current strength (Amps). Most chargers have both an ammeter and current adjustment, so you can use the charger even to charge motorcycle batteries, since the current required for operation is small.
And how to check the required amount of current? At normal current, a gray zinc coating should be obtained. If a loose black coating is obtained, then immediately reduce the current strength with the regulator. Well, if you get a light gray surface of the part, then you should slightly increase the current strength. From experience I will say that usually only 0.5 - 1 Ampere of current is enough.
As a current indicator and a simple voltage stabilizer, you can use an ordinary 12-volt light bulb, which should not glow too brightly when rubbing the part. The light bulb is connected to a break in the positive wire (this is clearly shown in the video under the article). If the lamp shines too brightly, then the current strength should be slightly weakened.
After applying the galvanized coating, thoroughly rinse the finished part with water. Well, if you used a solution of zinc sulfate not from an electrolyte, but from sulfuric acid, then I advise you to rinse the finished part first with a solution drinking soda to neutralize the sulfuric acid, and then rinse the part in water.
Well, how to restore the dimensions of the mounting hole of the parts? Indeed, often because of this, many people throw away the crankcase, and the crankcase or engine block is a licensed part, and its restoration is extremely important. And if the bearing turned in the block and the mounting hole lost its size (diameter), then it will not be difficult to restore the place of the bearing in the cast-iron block using the method described above using zinc wrapped with gauze.
But gearbox housings were always made of aluminum alloy, and engine blocks of new cars began to be cast from aluminum too (cylinder liners are coated with nikasil), which is not so easy to cover with anything. There are ways, but they are expensive and complex, applicable only in the factory. But this site exists for that, so that any master can do without complex factory equipment. There is always a way out, and I have always said that metal is no worse than plasticine and you can mold anything from it.
With the restoration of mounting holes for bearings in steel or cast iron housings (crankcases), there are no problems, since zinc is applied well to steel or cast iron. And in detail about the restoration of the landing hole in the headstock of his lathe TV-4, I showed in detail in the video below.
Well, it will not be possible to cover the hole in the aluminum crankcase, since zinc will not lie on aluminum, and after all, we do not have a super expensive metal sprayer in our arsenal, or, as I already said, complex galvanic equipment for coating aluminum. We don't need it. But you can easily cover the outer race of the bearing with a layer or layers of zinc. And if you buy a bearing not from some leftist, but from a reputable company (about right choice bearings), then it will survive several overhauls of the motor.
So that the zinc sulfate solution does not get inside the bearing to the balls or the separator, it is necessary to close the bearing on both sides with rubber gaskets and textolite plates superimposed on them (thickness 3 - 5 mm), and then pull this “sandwich” with a bolt and nut, and then bring to the outer race of the bearing minus the DC source.
The plates must be made of a dielectric (textolite, plastic, etc.), and not of metal, otherwise zinc will also be spent on coating metal plates, and you will not have enough zinc metal. I also recommend buying bearings. closed type, so there is more guarantee that the acid does not get inside to the balls.
And then covering the bearing with zinc, before installing it in the motor block, if desired, you can always remove sharp knife sealing washers covering the bearing, and the bearing will eventually become an open type (this is necessary so that it is lubricated with oil from inside the engine block).
And you can not immerse the bearing in the bath, but cover its outer race with a second more in a simple way, by rubbing with a piece of zinc wrapped in gauze and connected to the plus of a DC source.
I also want to note that to restore the size of a part (for example, a bearing cage), you can use a copper coating. Copper cannot be used as an anti-corrosion coating, but it is easy to restore the size. In addition, now in the customization of motorcycles, a fashionable trend called the old school (old school) has gone.
So, to cover all kinds of tubes with oil or gasoline wires, various small parts, it is not only possible, but also necessary to use a copper coating. After polishing such parts, your motorcycle will look not just cool, but super cool!!!
Okay, I digress a little, customizing is a sore subject for me, it’s understandable - there are no creative boundaries. Let's return to the banal restoration of the size of parts. One of the benefits of copper plating is that you don't have to mess around with acid. Since copper sulfate, and who remembers from the school chemistry course, it is also copper sulfate, from which the solution is prepared, it is very easy to find and buy at a hardware store.
Well, the second tangible advantage of copper coating is that you will not need to look for used batteries for the anode. After all, you can use a copper plate, or just a bundle of copper wires coiled into a cable. In water (preferably distilled), you will need to dissolve the maximum amount of powder blue vitriol. Select the current strength in the same way as I described above, when applying a zinc coating.
As you understand, there is nothing complicated in such a science as chemistry and electroplating at home. And now for you there is no problem of restoring a worn part, and you can restore any crankcase, or simply protect many parts from corrosion. And motorcyclists will be able to refresh quite brightly appearance your motorcycle. After all, I agree that chrome is chrome, but it's time to add variety to the design.
By the way, who wants to restore the zinc coating of the galvanized body of their car, then we read about it here, good luck to everyone and creative success!
Electroplating is often done by handmade craftsmen who make souvenirs for the soul or for sale. Copper plating of non-metallic objects is common: ceramic crafts, shells, bird feathers, leaves, twigs from trees, flowers, acorns, etc.
In order to galvanize a non-metallic object, it should be covered with a conductive layer. For living conditions graphite varnish in the form of a spray works best. To create a graphite layer, it is enough to spray the object from all sides, dry for 15-30 minutes and repeat the procedure several times.
To create a double-sided uniform coating, you need to use two anodes, placing the object to be galvanized between the anodes. The thickness of the coating depends on the time during which the object will be in the electrolyte. The longer the galvanization lasts, the thicker the metal layer on the surface will be.
Before galvanizing metal part it must be thoroughly cleaned of dust, small burrs, thoroughly degreased and dried.
After the item is galvanized, it must be washed in clean water, after which you can take it in your hands.
Electrolyte Recipes
For copper plating, sulfur electrolyte is most often used, consisting of copper sulphate and sulfuric acid. Sulfuric acid improves the electrical conductivity of the solution. Additionally, various additives are introduced that stabilize the electrolyte, make the coating more brilliant (if necessary). The introduction of brighteners allows you to get a mirror glossy surface without subsequent mechanical processing of the finished coating. But at the same time, it makes the coating brittle, not elastic.
All reagents used must be of the highest chemical purity, since impurities can impair the galvanizing process and the quality of the resulting coating.
- For a matte elastic coating per 1 liter of solution, you will need:
- 200 g of dry powder of copper sulphate (preferably purified, category h or hch)
- 160 g sulfuric acid
- 1.5 ml ethanol (can be measured with a syringe) or phenol
- 2-4 grains of granulated gelatin
To prepare the electrolyte, first half a liter of distilled water is heated to a temperature of about +80 ° C, copper sulfate is dissolved in the water, the solution is filtered. Sulfuric acid is added to it, then the volume of the solution is brought to 1 liter. All other ingredients are added, then the solution is set to cool and settle for several hours.
Copper plating according to this recipe will be matte, but a feather or a leaf from a tree can be bent or given to it desired shape, heating the product. If you want, then the product can be given a glossy sheen by careful grinding, but sometimes it is difficult to do this, you need special tools, for example, an engraver.
- Recipe for a shiny copper plating. For 1 liter of solution you need:
- 200 g copper sulfate
- 130 g sulfuric acid
- 1 drop unithiol (sold in pharmacies)
- about 0.07 g thiourea
- 0.05 g salt
The coating will turn out shiny, but not suitable for bending objects. This kind of electrolyte can be used to obtain a polished finish coat not only for souvenirs, but also for technical details.
Galvanic etching. safe way
With the electroplating process, it is possible not only to cover the surface of the part with a thin metal film, but also to etch patterns on the metal surface (knife blade, cutlery, anything else). Galvanic etching allows you to get patterns with clear outlines, smooth edges and a depth of the same size. This will require the same equipment as for galvanizing, but in this process the part to be etched will act as the anode. Typically, stainless, acid-resistant steel surfaces, which are difficult or even impossible to chemically etch, are etched in this way.
Pickling process: 
- carefully polish the part, rinse, degrease (for example, with alcohol), heat slightly, apply a layer of wax on it; on wax, perform the desired pattern, scratching the wax to the metal;
- fix the object and the copper plate on the rods in a galvanic bath so that the pattern faces the copper plate; the distance between the part and the plate is about two centimeters;
- pour a saturated solution of sodium chloride into the container (4 tablespoons per 1 liter of distilled water), connect a power source (for example, a charger from mobile phone), positive contact on the part, negative contact on the copper plate;
- wait about 40 minutes;
- remove the part, rinse in water, heat and remove the wax.
Instead of wax, you can use nail polish, bituminous varnish or a special primer. Instead of salt - chemically pure copper sulfate. Instead of a copper plate, you can take an object made of steel or iron, for example, a self-tapping screw, a nail.
This technology is suitable not only for steel surfaces, but also for objects made of zinc, nickel, copper, brass. But they require other chemicals, much more harmful, so they are not used at home.
You can cover almost any object with a layer of copper or other metals, including leaves, branches, shells and bird feathers. In order for electroplating at home to turn out the first time, it is necessary to make the copper plating object electrically conductive. For this, a graphite spray is used, and if electroplating at home is applied to hard objects, you can replace it with a soft one. with a simple pencil. The electrolyte in which copper plating occurs can be purchased from ready-made, but you can cook it yourself. Typically, the electrolyte consists of copper sulfate, sulfuric acid and distilled water. If you calculate the proportions correctly, you can use battery electrolyte instead of sulfuric acid and make the solution yourself.
Depending on the size of objects for copper plating, the container can have different shapes and sizes. After the container is filled with electrolyte, anodes are suspended, fixed on its edges, the role of which is played by copper plates. The cathode - an object for copper plating - is usually hung in the middle between them. For hanging, it is most convenient to use copper wire of medium hardness. If the object is light and constantly floats, it can be additionally fixed from the other end. For a heavy and shape-retaining object, a thin and soft wire is sufficient, which is fixed on the surface of the cathode. Then the electrodes are connected, with the positive end to the anodes, and the negative end to the cathode. Two copper plates ensure even distribution, especially difficult cases can be used large quantity plates.
The power supply is first turned on at a low power of about 0.1 amperes until a layer of copper ions wraps around the cathode. The voltage gradually increases, reaching the required 2 amperes. Excess voltage will damage the coating. It will remain strong, but there will certainly be excessive graininess, roughness and it will be difficult to achieve shine. Such a coating is not considered defective, and some ideas require such execution. Depending on the type of copper-coated surface and the size of the object, the process can take from an hour to a day. In less than an hour, only very small objects can be coppered in a thin layer. The required copper thickness also has great importance for the coppering time, and for a thick layer of time it will take much more than for decorative coating. You can take out an object and evaluate the result an unlimited number of times.
After several hours in the galvanic bath, the object serving as the cathode is completely covered with a thin layer of copper. When the entire surface begins to shine, the electroforming process can be considered complete. Then the copper-plated object is washed in distilled water, which helps to avoid further oxidation. If the process proceeded correctly, then the copper layer will completely repeat the texture of the selected item, up to the smallest details. It takes great skill and practice to copper-plat insects and plants correctly in such a way as to preserve their original appearance. Even upon closer inspection, the fibers or structure of the copper-plated material will be visible. In order for graphite and copper to lay down qualitatively on the surface of an object, it must be cleaned as thoroughly as possible before starting copper plating.
If the parameters of the thing to be coppered allow it, you can clean it before copper plating using sandpaper. This will remove the oxide film from the surface. A hot soda solution degreases any surface well, but after using it, you must definitely rinse the thing running water. In the event that no degreasing agents can be applied, as in the case of leaves, flowers or feathers, it remains to follow all other recommendations and hope for success. There is also a way to copper-plating parts, without lowering them into the electrolyte. This method is especially well suited for products made of zinc and aluminum. To apply this method, you will need a piece of stranded copper wire, or thin copper wire folded several times. The insulation is removed from the wire and it unwinds on one side to make it look like a brush or brush.
For the convenience of work, any solid and convenient object is tied to the other end of this brush as a handle. In this case, the second end of the wire is also stripped and connected to a current source, to the positive terminal. But the voltage for operation should not exceed 6 V. The electrolyte for this method is prepared in the same way as for copper plating in any container. It is recommended to choose a wide container so that it is convenient to dip a wire brush into it. The item that needs copper plating is also placed in a wide container with low sides that exceeds its dimensions. The product is connected to a current source with a negative terminal, the voltage should also not exceed 6 V. Then the end of the wire, turned into a brush, is dipped in an electrolyte solution and carried along the part intended for copper plating.
An important condition is that the brush should not touch the surface of the copper-plated object. In order for copper to cover an object with a thin and even layer, an electrolyte must always be present on it and at the end of the brush. In this case, a negatively charged part can attract copper ions to its surface in the same way as when it is in a container with an electrolyte. The process requires constant human intervention and takes much longer, but if all conditions are met, the surface will be covered with a thin, shiny layer of copper. This method is good for large parts for which it is impossible to find a suitable container for the electrolyte. Such large-sized objects are coppered in parts.
There are two types of galvanization - electroplating and electroplating. In the first case, a non-removable galvanic coating is obtained, which changes the characteristics of parts and objects. Depending on the goals pursued, processed products acquire new properties: decorative effect, good reflectivity, resistance to mechanical impact and corrosion, wear resistance. With the help of electroforming at home or in production, exact copies of samples are created (the deposited metal layer is separated from the matrix).
Galvanization technology: general information
Regardless of whether performed or at home, the treatment is carried out in a container filled with a conductive solution.
The object is placed between two soluble or insoluble anodes and connected to the negative terminal. The anodes are connected to the positive contact. The optimal ratio of cathode/anode areas is 1:1.
The galvanization process starts when the circuit is closed electrical network- from this moment, the transfer of metal ions to the negatively charged product (cathode) begins. As a result, a coating of the desired thickness is formed on the object.
Choice of type of coverage
If the priority is the solution of technical problems (change in electrical conductivity and anti-friction properties, increase in reflectivity, strength, resistance to corrosion), then silver, nickel, copper are used. For decorative purposes, precious metals are commonly used: rhodium, gold, silver, palladium.
This division is very conditional. With the help of silver plating (gilding), it is possible to obtain a high-quality protective coating that is resistant to aggressive environments. Copper plating is also used in the decoration of products (such a coating is subjected to additional oxide treatment).
Practice shows that it is possible to seriously increase the strength of workpieces by galvanizing their surface only in production. It is difficult to achieve the desired result in a home workshop, so the work of the craftsmen is primarily aimed at increasing the attractiveness of the object.
Electroplating Method
Do-it-yourself electroplating at home requires the use of special equipment. It doesn't have to be professional at all. Masters find an affordable replacement.
When preparing a galvanic installation with his own hands, the master will have to find a plastic or glass bath of the required volume. A sufficiently strong, electrically insulating, acid-resistant container is required. It must fit the workpiece and right amount electrolyte and anodes.
The power source must have an output voltage and current regulator - this will allow the master to change the processing parameters during the work. Usually the rectifier becomes the power source.
An important element of a home installation is soluble and insoluble anodes.
For the process to proceed correctly, the masters observe optimal ratio workpiece and anode areas (1:1). Suspension devices provide support to the object and contribute to the correct distribution of current.
Electroplating process
Electroplating at home is carried out using reagents. At this stage, difficulties may arise - many chemical substances available only to those who have previously obtained permits.
Need to take care of proper storage components. Reagents, as well as ready-made electrolytes, are placed in glass or strong plastic containers with lids.
When preparing the composition, it is extremely important to measure all components with great accuracy - it is best to use electronic scales for this.
Preparatory process
The quality (homogeneity, strength) of the finished coating directly depends on the correctness of the preparation of the surface for galvanization. In many cases, removing dirt and degreasing is not enough - sandblasting may be necessary. Sometimes grinding with special pastes or sandpaper is required.
At home, alcohol and other organic solvents are often used to remove greasy film and other contaminants from surfaces. Degreasing solutions may also be used.
In preparation for the galvanization of steel and cast iron products, a solution containing soda ash, caustic, silicate glue is used (based on 1 liter - 50 g, 20 g and 5-15 g, respectively). The temperature of the solution is 70-90°C. To clean items made of non-ferrous metals, a solution of sodium hydrogen phosphate and household solid soap (10-20 g / 1 l) is used. During the procedure, the temperature is 90°C.
Safety
When carrying out galvanic operations, the master is obliged to observe safety precautions. The danger of this technological process is the use of toxic chemicals. The situation is complicated by heating the electrolyte to high temperatures. Harmful fumes are striking respiratory system, there is a risk of chemical burns to the skin and mucous membranes.
Work must be carried out in a non-residential area equipped with good ventilation - in a workshop, annex, garage. Grounding is required.
Eyes must be protected with goggles. Hand gloves should be soft enough, but durable. You will also need an oilcloth apron and rubber shoes.
You can not drink or eat at the workplace - there is a high risk of settling on products harmful substances that lead to poisoning.
Before starting work, it is necessary to study the special literature with accessible description process features.
Precious metals in electroplating
Electroplating gilding (silver) is used to give the product decorative properties. When using the galvanic method, craftsmen receive not only an ennobled precious metal item, but an exact copy of the original product. It can be both simple and complex. The layer of metal deposited on the workpiece is separated from the base.
The surface of objects made of ferrous metals is preliminarily copper plated before silvering. The temperature of the solution depends on the composition used. The anodes are made from 999 purity silver.
The electroplating process requires the use of ready-made electrolytes. The part is pre-cleaned and treated to improve adhesion with electroplated nickel. If the object is made of aluminum and its alloys, it is impossible to apply gilding at home. The gilded object is thoroughly washed and then air-dried.
Nickel in electroplating
A layer of nickel is applied to the workpiece before the gilding procedure. Nickel has good protective properties - it protects the surface of the workpiece from the action of aggressive factors, withstands contact with various media, and prevents oxidation and corrosion.
Nickel plating looks great. The thickness of the layer is different - from 0.8 to 55 microns. When processing objects, sulfuric acid, hydrochloric acid or sulfamic electrolytes are used. Temperature, acidity, current density depend on the composition of the solution.
Copper in electroplating
copper plating:
- protects the workpiece surface from corrosion;
- creates a surface layer with low electrical resistance.
- It should be noted that without preliminary nickel plating cast iron surfaces can only be copper-plated in an alkaline electrolyte. Such a solution is used in industries.
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