Currently, the problems of chrome plating at home are quite acute. The reason for this is the rather high price tag for such services from specialized workshops. Chrome plating of parts and components of mechanisms not only gives them a very spectacular and attractive appearance, but also improves a number of technical and operational indicators. Thus, a layer of chromium applied by one method or another prevents corrosion of steel, which means it prolongs the useful life of the product. According to metallurgists, chromium plating also increases frictional wear resistance, and even increases the fatigue strength of metal structures.
General provisions
The technology of the process is quite simple, it can be easily recreated at home. Chrome plating is the application of a surface or diffusion layer to a steel or plastic product.
You can apply a layer by several fundamentally different methods:
- plating bath;
- galvanic brush;
- flame spraying;
- ionic-plasma technology.
The last two methods are very energy intensive and require expensive equipment. Not suitable for processing parts at home. Chrome plating obtained using flame spraying is much better. But the best result is obtained by ion-plasma treatment in the glow discharge of a vacuum chamber, since in this case the atoms penetrate deep into the product, and the layer has very good adhesive properties.
Advantages and disadvantages of electroplating brush
The main advantage of the so-called galvanic brush is the lack of restrictions on the overall dimensions of the workpiece. The possibilities of galvanic processing are limited by the size of the bathroom itself. Chrome plating at home for large and heavy items is difficult to implement in practice: you will need a large tank, a beam crane to lift heavy items, a large volume of solution, etc.
Apply a layer of high quality and evenly, so that the surface is uniform and shiny, not every layman can. Only professionals who have been doing such work for a long time and on an ongoing basis can cope with such a task. This is the main disadvantage of this method.
For chrome plating of parts at home, the simplest galvanic bath is most often equipped.
Rules and safety requirements for electroplating work
It is forbidden to operate the unit in a room where people live. An ideal place for organizing production is a garage or a shed on the street.
In the summer, when it's warm outside, you can set up a mini electroplating area right outside under the roof of the veranda. In the conditions of the city in high-rise buildings for chrome plating at home, it is permissible to use the balcony area. In this case, the frame, if any, should be wide open, and the doors and windows to the apartment should be closed.
It is mandatory to work in industrial rubberized gloves for electricians in order to prevent electric shock and avoid the harmful effects of chemically active elements. To minimize the harmful effects of toxic fumes, wear an industrial gas mask or respirator. Goggles and an apron made of dense rubberized fabric are used to protect against splashes.
Required tools and supplies
To implement chrome plating at home, you will need to buy or find the following items to assemble the installation:
- glass tank (at home, an ideal substitute is a regular three-liter can for seaming);
- bath made of non-metallic material (a plastic basin is well suited for this purpose);
- thermal insulation materials;
- heater (usually a boiler coil is used);
- anode (an alloy of lead with antimony with a mass fraction of the first 93% is ideal for the manufacture of this element, the material is rather scarce,therefore, in chemical chromium plating at home, technical grade lead is most often used);
- the cathode is a kind of terminal that closes on the workpiece being processed);
- mercury laboratory thermometer;
- rigging that allows you to hang the item in the bathroom;
- bathtub lid (wood and plywood material is good);
- AC-to-DC converter with adjustable resistance; to ensure the flow of physical and chemical processes throughout the volume of the jar, the minimum current strength should be 18 amperes.
If desired and with appropriate qualifications, you can implement a controlled chromium plating process at home. The technology involves galvanic processes at a certain temperature (depending on the surface area of the product, the volume of liquid, etc.) in order to obtain the maximum beneficial effect and layer quality.
The above is a simple installation diagram. The numbers on it mean: 1 - glass container (jar), 2 - anode (or anodes), 3 - chrome-plated part (cathode), 4 - electrolyte solution.
To control the temperature, you will need a simple thermocouple and a potentiometer. Similar equipment can be easily found at flea markets.
Do I need to clean the surface of products?
The result of the process depends on many factors. But the biggest influence is, of course, the quality and cleanliness of the surface on which it will be applied.chrome layer. In order to rationally use time, it is recommended to carry out all work on the preparation of parts during the preparation and heating of the electrolyte. Heating the electrolyte to operating temperature takes no more than three hours.
Therefore, we can say that cleaning the surface of products is a very important step in the technological process. And if you neglect it, then the quality of the chrome layer will be very poor, and soon such a coating will begin to swell and peel off.
How to properly clean surfaces
The best way to clean the surface of grease stains and dirt is to immerse them in an ultrasonic bath. That's what they do in a production environment. This is a very effective method. Currently, you can relatively inexpensively purchase a small bath. But such costs will justify themselves only if you plan to regularly and often set chrome plating modes.
Usually people clean parts by hand. Yes, this method is less productive, and the cleaning quality is sometimes not as good either, but still it is a good alternative to purchasing an ultrasonic cleaning bath.
It is believed that it is best to chrome surfaces with a slight roughness. This ensures good and reliable adhesive interaction of materials. Therefore, it is recommended to go over the part with fine-grained sandpaper.
Washing operation
When washing the product, the first step is to rinse it in water (preferably running water). This will eliminate coarse foreign particles. The next step is to degrease the part. Alcohol and acetone leave a slight streak when dry. Therefore, it is recommended to prepare a special solution: add 150 grams of caustic soda, 50 grams of soda (calcined) and 5 grams of silicate glue to one liter of water.
The prepared solution is heated to a temperature of at least 90 degrees Celsius, and parts are placed in it for 20 minutes. After being removed from the cleaning solution container, the products are removed and dried, then further technological operations can be carried out.
Electrolyte preparation
You can easily prepare an electrolyte solution at home. Chromium plating takes place in a solution of sulfuric acid and chromic anhydrite in water. This solution is called an electrolyte. The concentration of sulfuric acid is approximately 3 grams per liter of water, chromic anhydride is about 300 grams.
Special requirements are also imposed on the purity of water. Ordinary tap water is unsuitable here: due to the high concentration of impurities, the process will proceed unpredictably, and the result will be of very poor quality. Thus, to prepare the solution, you need to buy distilled water in sufficient quantities.
Before adding the solution component, the water must be heated to 60 degrees Celsius. This guarantees the complete dissolution of all components and the production of high-quality electrolyte for chrome plating at home. Electroplating is that branch of science and technology that requires utmost attention andaccuracy from the performer and work manager. Chromic anhydride is a very toxic and dangerous compound. Therefore, it can only be used in well-ventilated areas. It is best to use a chemical reagent cabinet with a powerful exhaust hood. If you take the matter seriously, then such a cabinet can and should be made with your own hands. Chrome plating at home must be carried out in strict accordance with all safety requirements and regulations.
Preparation of electrolyte for work
Before immersion in the electrolyte of the product, it is necessary to pass the current through the solution "idle". In the event that all system parameters were calculated correctly, and the current was selected to the desired value, the solution should acquire a dark brown hue. The general recommendation is as follows: to ensure the flow of the process throughout the entire volume of the electrolyte, a current of six and a half amperes per liter of liquid is required. Current is passed for 4 hours.
After the liquid has darkened, it needs to settle. Therefore, for at least one day, the bath should not be touched.
Electrochrome plating
It is first necessary to report the temperature of the working medium (electrolyte) 53 degrees Celsius. This will provide the most favorable conditions for the flow of all processes.
Then it is necessary to hang the products on the support so that it is completely immersed in the electrolyte. It is necessary to wait some time (5-10 minutes) for the temperature between the electrolyte and the product to equalize.
It is not recommended to immediately carry out the mode on a real part. First you need to test the technology on some kind of prototype. Even if it is spoiled, it's not a pity.
As soon as the patterns of layer formation and its dependence on the voltage supply time, electrolyte composition, etc. are revealed, it is possible to start mass production of products.
Features of do-it-yourself plastic chrome plating at home
It is not possible to use a galvanic bath when coating plastic products due to the fact that plastic is a dielectric (except for special materials designed for specific tasks) and does not conduct current, which means it cannot act as a cathode in the wiring diagram.
Therefore, plastic products are covered with a decorative layer of chromium using a completely different technology: initially, two or three layers of a protective auxiliary coating are applied to the product, and only then a layer of chromium. And despite the small thickness of such a layer, it serves well and copes well with the tasks that were assigned to it.
Preparation of plastic items for chrome plating
As well as products made of steels and metal alloys, plastic structural elements must also be well washed and degreased before chromium plating. It will not be superfluous to treat all surfaces with fine-grained sandpaper. Such a set of operations will ensure reliable contact between the plastic and the deposited metal layers.
Treatment in sulfuric acid solution
Mandatory stepPreparation for metallization of plastic products is the etching operation. The essence of this operation is as follows. A special solution is being prepared (60 grams of chromic anhydride, 150 grams of phosphoric acid (rust converter), 560 grams of sulfuric acid per liter of distilled water). Products are immersed in the solution for a certain time. It's hard to say exactly how long it will take. It is determined empirically and depends on many factors. Thus, plastic chrome plating at home does not differ in repeatability and constancy, and each new mode can take place with its own characteristics. An important point: before immersing plastic products in the bath, the temperature of the environment must reach at least 50 degrees Celsius.
Only after carrying out all of the above operations, you can start applying a metal coating.
