Rhodium Plating
Due to its many advantageous properties, rhodium is often utilized in plating processes in order to endow other metals with its beneficial characteristics, most commonly for protective purposes. As a result, rhodium plating is a typical process in many industries including: commercial, where it is widely used for jewelry for plating on materials such as white gold and platinum; medical, in which plating is used to give optical instruments extremely hard surfaces; electronics, used to protect sensitive electrical instruments such as electrical contacts and capacitors; industrial manufacturing, in order to strengthen weak materials for processing (although it is a very expensive option); and telecommunications, for the surface protection of devices such as mobile phones. However, although there are multiple practical applications, rhodium plating is most commonly utilized for decorative purposes.
Not able to maintain plating for a long-duration, rhodium is most commonly plated using an electroplating process. In the jewelry industry, this process is known as rhodium flashing. In rhodium electroplating, the surface of a metal object is coated with a layer of a rhodium through electrochemical means, which means that both a chemical solution and an electric current are utilized in order to enable deposition. However, although it is not as common, rhodium plating may also be performed utilizing an electroless plating process. In electroless rhodium plating, an electrical current is not utilized whatsoever; instead, the process depending entirely upon a chemical reaction. In this chemical reaction, the rhodium is immersed in an aqueous solution that is often referred to as a bath solution. Without an electrical current, the rhodium reacts as a result of the introduction of a reducing agent into the bath solution. The reducing agent, which is typically something like sodium hypophosphite, functions to release hydrogen and causing the rhodium's ions to react and to be produce a negative surface charge that results in deposition. The addition of rhodium to any other metallic surface provides a very hard and reflective, white-colored surface.
