Silver plating is the coating of objects with silver. There are several technical processes for this. The applications of this traditional process are very diverse. What is silver plating?Inelastic materials are coated with silver, which gives them certain properties. This coating is very thin, which is why it could detach from elastic materials. Suitable materials are the metals steel and iron, copper, brass, tin, zinc, lead, nickel and non-metallic materials such as plastics and glass. This makes these materials very good conductors of electricity, better resist corrosion and look better.
Possible processes are:
This simple process works by vaporizing the silver, which then spreads out as a gas in a furnace or vacuum chamber and condenses out on the cooler surface of the item being silver plated.
The objects are immersed in a silver electrolyte. Very often this is potassium silver cyanide with conducting salts. With the help of an electrical voltage, a silver coating can be deposited. This process is even used for objects made of real silver. The coating of fine silver conceals solder joints and colour differences. The electroplating technique was developed as early as the 1830s.
Silver also reaches surfaces through a hot cyanide-containing bath of silver nitrate.
In a cold aqueous solution of silver nitrate, hydrazine sulphate, ammonia and sodium hydroxide, non-metallic objects can be coated with silver (including mirrors and Christmas balls), which would not tolerate too much heat and also do not conduct electricity.
A process no longer used today because of health hazards was fire silver plating.
Fields of application
Silver has the highest electrical conductivity of all metals, and it is also the most lustrous metal. Another important property is its resistance to corrosion. These three properties result in the most important applications. In the electrical industry, a silver layer on conductors serves to improve electrical contact and at the same time to protect against corrosion. Corrosion protection is also important for the chemical industry. As silver looks very decorative due to its strong shine, jewellery as well as art and utility objects such as cutlery are silver-plated. Before the invention of corrosion-resistant steel in the early 20th century, silver was an important corrosion protection on cutlery. The high optical reflectivity leads to its use in mirrors and reflectors. When glass is silver-plated, the process is technically called mirroring.
Examples of silver plating
The most important examples are found in the electrical industry and related areas. Here, contacts and plug connections are usually silver-plated by electroplating. The applying industries are electrical engineering and electronics, precision mechanics, telecommunication technology, the automotive industry as well as mechanical engineering and equipment manufacturing.
Various examples would be:
- Silver plating of small connectors
- silver plating of components for medium and high voltage as well as high frequency technology
- galvanic silver plating of complex geometries
- Hand galvanizing of technical components
The jewellery industry also uses a lot of silver plating.
Furthermore, components of vintage cars are often given a silver coating for restoration purposes. Musical instruments and their accessories can be silver-plated, such as flutes and trumpets or the strings of strings. Due to the high ductility of silver, practically any relatively rigid object can be silver-plated.