Electrolytic coppering is a process carried out in electrolytic baths in which the part to be coppered acts as a cathode, while the anode consists of cathodes in pure copper. Even though most of the times a coating is not an end in itself, the coppering represents the middle layer being the background for further processes , like nickel-plating, silvering, gilding, brass plating, chroming, etc.
The electrolytic coppering is divided into two categories: ALKALINE COPPERING and ACID COPPERING.
In the alkaline bath the electrolyte is made up of a complex cyanide solution Na₃Cu(CN)4, while in the acid one of a concentrated copper sulphate added to sulphuric acid to increase the electrical conductivity and improve the attachment of the anodes;
The cyanide baths are characterized by a high penetrating and may be applied directly to zamak, brass, iron and zinc alloys which differs them from the acids who need a protective layer of alkaline copper to avoid the typical effect of cementing of the metal.
Characteristics of the alkaline coppering:
Characteristics of the acid coppering:
Electrolytic nickel-plating is maybe one of the most important and extended process in electroplating, it can be applied by unlimited fields of application: from the ones in which nickel is used as base layer before applying precious metals as preparation for jewelry and crockery, as protection to bumpers of cars, motorcycles, bikes, bathroom accessories, kitchen equipment, etc. In the process of electrolytic plating, the articles are positioned at the negative pole, while the positive pole is made out of a nickel cathode, the main characteristic of this process is to fuse a single layer deposit both decorative /esthetic as well as the technical/function aspects, and to provide a protective barrier against corrosion. Almost all the nickel-plating baths are composed of nickel sulfate, nickel chloride and boric acid, from this mix arises a stable solution with values contained in a rather large range, according to their aesthetic appeal they can be divided in glossy- or matt baths. Through the adding shining agents and tensioactives to the base formula one can obtain a shiny surface without need of further polishing at the end, which means a significant saving of time, material and manpower.
Main characteristics of nickel deposit:
Gold is the chemical element and atomic number 79. It’s symbol is Au, has always been considered symbol of wealth, health and prestige. It is a metal that is soft, flexible, and malleable of a yellow color that is not attacked by air and not by most of chemical reagents, having the characteristic to be resistant against corrosion and oxidation, gold is mainly applied in decorative fields
Electrolytic gilding is an electrolytic process in which a less noble metal is covered with a precious metal, both to avoid corrosion as well as a decorative/aesthetic value.
The electrolytic deposit of gold is mainly done in hydrocyanic baths both for technical as well as decorative use, these baths are divided in three categories according to their PH value:
Normally this type of electrolytes use a composition of gold cyanide and potassium KAu(CN)2 , with a content of Au 68%, this allows deposits of gold layers of 24k.
Silver is a noble metal with a more white color, it is a soft metal and the best heat conductor among all metals, even more than copper.
Electrolytic silvering consists of depositing a layer of silver metal on articles that are made out of a different material and can be distinguished in glossy and matt both for decorating as well as for technical/functional use.
The articles to be covered are normally immersed in a bath containing silver cyanide and sodium and potassium cyanide, with pure silver plates as anodes. By adding shining agents, one can obtain a shiny surface without need of further polishing.
The main characteristics of such deposit are:
COLOR: milky white
HARDNESS: 110 HV
SPECIFIC WEIGHT: 10,5 g/cm³