The words “gilded”, “silver-plated”, “chrome-plated”, “chrome-plated” or “nickel-plated”, familiar to all, have already firmly entered the vocabulary of modern man and are perceived by him almost automatically. No one even thinks that behind all these words is a technology that has allowed a person to reach the modern level of civilization - electroplating.
Electroplating - what is this process?
An electrochemical process in which, under the influence of an electric current, metals are deposited on a selected surface, is called electroplating. Such a process can be applied to any subject, even non-metal. This is what became decisive for the widespread use of electroplating in various industries. Using it, you can gild, silver, nickel and chromium-plated any objects, ennobling their appearance for decorative purposes or changing the physical and chemical properties of the surface for purely practical purposes (to increase wear resistance, increase resistance to aggressive environments, etc.). The equipment is a galvanic bath.
Types of Electroplating
There are two types of this technology that are widely used not only in many sectors of modern industry, but also at home. The first - electroforming - has as its goal the creation of exact copies of the surfaces of an object from the metal deposited on them. The second, the most common in everyday life and in production, consists in creating a thin - no thicker than a human hair - covering the entire surface of an object and is called electroplating.
What is a plating bath?
Since galvanic processes occur due to electrolysis, it is natural that electrolytic solutions and special mechanical and electrical equipment are used. Galvanic baths are a combination of all of the above components of the process, but the main components to which increased demands are made are a solution (electrolyte) and a container for it. This is especially important when it comes to the use of electroplating or electroplating at home.
Elevated general requirements are imposed on containers for electroforming, which, despite the fact that there are a lot of types of these containers, all of them must strictly comply. They must be sealed and chemically neutral to the solution used, able to maintain the required thermal conditions (heating of galvanic baths and their cooling must be controlled), as well as convenient and safe to maintain. Bathtubs are made of various materials.
Electroplating Bath Analysis Methods
Thanks to modern developments, new possibilities have appeared for the analysis of the electrolyte used in the galvanic process. This is necessary for a high-quality result of the process, obtaining a more uniform and durable coating. Analysis of galvanic baths in modern conditions can be carried out using chemical and physico-chemical methods. In the second case, photometric studies, polarographic, ampereo, and potentiometric methods are used, which give better results in determining the composition of the electrolyte.
Protection of galvanic tanks
One of the problems of galvanic processes is the protection of electrolyte containers from the destructive effects of a solution (acidic or alkaline) in which electrolysis proceeds. If the bathtub is made of a neutral material, such as plastic, then there is no problem. But this is only possible in cases with small volumes. If we take industrial plants, then in galvanic plants, solution tanks are made of metal. In this case, there is a need to protect them from:
- contact with the solution, which ensures a longer service life;
- corrosion of the metal, creating unnecessary impurities in the solution;
- distortions and changes in the electric field.
Such protection can provide the lining of galvanic baths, carried out by sheet polymer materials using hot air welding.
The manufacture of plating baths at home
There are a lot of people who want to have electroplating in their home or garage. But it should be noted that this process is unsafe. Harmful and explosive vapors, caustic and even poisonous solutions, the use of electricity make it difficult from a safety standpoint. But for simple works, such as copper plating, chromium plating, nickel plating of small objects, a plating bath can be assembled from improvised means. And even in this case, it is necessary to observe several important requirements:
- the capacity for the solution must be rigid, chemically neutral and dielectric;
- mandatory exhaust ventilation;
- the presence of a sufficient amount of clean water - the simplest process requires the use of about five washes;
- the availability of tanks and means to neutralize waste solutions and wastewater.
The simplest version of a galvanic bath can be made of a plastic canister by cutting off the lid with the neck and reinforcing the sides with reinforcing material. Then, window or car seals must be put on the walls of the tank along the cut line. The next step is to fasten the lid with the help of
piano loops to one side of the canister and fasten the latches to the lid and the wall of the container on the opposite side. The neck in the lid is connected to the hose to remove the vapors out - the simplest exhaust ventilation.
Now it remains to make three holes for the contact rods in the upper part of the tank along the cut line. It is desirable to make rods from a copper tube with a diameter of 10–20 mm, preferably thick-walled. The ends of the tubes are flattened and holes are drilled in them for connecting the poles from the power source. Anode plates are hung on rods placed at the edges and connected to the plus of the source. A cathode component suspended from a negative wire is suspended on a central rod. Current
and voltage are selected depending on the
volume of the bath.Schemes of homemade plating baths
The simplest scheme of a galvanic bath includes only three operations: preparatory, the actual process of galvanization and finishing. The first is to clean, degrease, etch and polish the item or part - preparation. The third operation allows you to bring the part already covered with a layer of metal to a "salable" appearance by passivation, polishing, etc. Each operation must end with washing in clean and cold water. And if the parts were treated with alkaline solutions, then it is necessary to rinse first with hot and then with cold water.
The part to be coated is connected to the negative wire of the device (cathode) and lowered into the electrolyte. The positive wire is connected to the electrode of the covering metal (anode), which also falls into the solution. Electrolysis will cause the anode (+) to dissolve and the metal to deposit on the cathode part (-).
The importance of electroplating for modern production
The galvanic bath in which the process of electroplating or electroplating takes place, on an industrial scale is both the brainchild of progress and its mover. Because, thanks to galvanic coatings, the characteristics of parts and mechanisms are improved, their production is cheaper, the highest accuracy of mating is achieved, wear resistance is increased and anticorrosion properties are increased.