Familiar to all the words "gold-plated", "silver-plated", "chrome-plated" or "nickel-plated" have already firmly entered the lexicon of a modern person and are perceived by him almost automatically. No one even thinks that behind all these words lies a technology that 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. This process can be applied to any object, even non-metal. This is what became decisive for the widespread use of electroplating in various industries. With it, you can gild, silver, nickel and chrome plating 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, increaseresistance to aggressive environments, etc.). The equipment in this case is a galvanic bath.
Types of electroplating
There are two types of this technology, which are widely used not only in many branches of modern industry, but also at home. The first - electroplating - 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 both in everyday life and in production, is to create a thin - no thicker than a human hair - coating of the entire surface of the object and is called electroplating.
What is a plating bath?
Since galvanic processes occur as a result of electrolysis, it is natural that electrolytic solutions and special mechanical and electrical equipment are used. Electroplating baths are a combination of all the above components of the process, but the main components that are subject to increased requirements are the solution (electrolyte) and the container for it. This is especially important when it comes to using electroplating or electroforming at home.
Greater general requirements are imposed on containers for electroforming, which, despite the fact that there are quite a lot of types of these containers, all of them must strictly comply. They must be hermetic and chemically neutral to the solution used, capable of maintaining the required thermal conditions.(heating of plating baths and their cooling must be controlled), as well as convenient and safe maintenance. Bathtubs are made from a variety of materials.
Methods for analysis of electroplating baths
Thanks to modern developments, new possibilities have emerged for the analysis of the electrolyte used in the electroplating process. This is necessary for the qualitative 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, ampero- and potentiometric methods are used, which give better results in determining the composition of the electrolyte.
Protection of galvanic capacities
One of the problems of galvanic processes is the protection of electrolyte containers from the damaging effects of the solution (acidic or alkaline) in which electrolysis takes place. If the bath is made of a neutral material, such as plastic, then there is no problem. But this is possible only in cases with small volumes. If we take industrial installations, then in galvanic production, containers for the solution are made of metal. In this case, it becomes necessary 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 be provided by the lining of galvanic baths,carried out by sheet polymer materials using air hot welding.
Making electroplating 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 not safe. Harmful and explosive vapors, caustic and even poisonous solutions, the use of electricity make it difficult from a safety standpoint. But for simple work, such as copper plating, chrome plating, nickel plating of small objects, a plating bath can be assembled from improvised means. And even in this case, several important requirements must be observed:
– the container for the solution must be rigid, chemically neutral and dielectric;
– exhaust ventilation required;
– availability of sufficient clean water – the simplest process requires about five flushes;
- availability of containers and means for neutralizing waste solutions and wastewater.
The simplest version of a galvanic bath can be made from a plastic canister by cutting off the lid with a neck and reinforcing the sides with reinforcing material. Then, window or car seals must be put on the walls of the container along the cut line. The next step is to fasten the lid with piano hinges to one side of the canister and fasten the latches to the lid and container wall on the opposite side. The neck in the lid is connected to a hose to remove vapors to the outside - the simplest exhaust ventilation.
Now it remains to make three holes for the contact rods in the upper part of the container along the cut line. It is desirable to make rods from a copper tube with a diameter of 10–20 mm, preferably a thick-walled one. The ends of the tubes are flattened and holes are drilled in them to connect the poles from the power source. Anode plates are hung on the rods located at the edges and connected to the plus of the source. A part, which is the cathode, connected to the negative wire, is suspended on the central rod. Current
and voltage are selected depending on the volume of the bath.
Schemes of homemade galvanic baths
The simplest scheme of a galvanic bath includes only three operations: preparatory, the actual galvanization process and finishing. The first is cleaning, degreasing, etching and polishing an object or part - preparation. The third operation allows you to bring the part already covered with a layer of metal to a “tradeable” 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 imperative to flush first with hot and then cold water.
The part to be coated is connected to the device's negative wire (cathode) and immersed in the electrolyte. The positive wire is connected to a covering metal electrode (anode) which is also lowered into the solution. Electrolysis will cause the anode (+) to dissolve anddeposit metal on the cathode part (–).
The Importance of Electroplating for Modern Manufacturing
The electroplating bath, in which the electroforming or electroplating process takes place, is both the brainchild of progress and its mover on an industrial scale. Because thanks to galvanic coatings, the characteristics of parts and mechanisms are improved, their production is cheaper, the highest mating accuracy is achieved, wear resistance increases and anti-corrosion properties increase.
