Chrome is one of the transition metals and cannot be found naturally in its purest form. That's why it is mined as chromite or chrome iron ore. Chrome is a corrosion and tarnish-resistant metal with a high degree of hardness. Its properties and blue shimmering sheen make it a popular surface in the automotive sector as well as in the furniture industry and many other sectors of industry. It is normally used here for decoration or as an eye-catching feature.
It is possible to deposit chrome layers with a higher hardness than with polished chrome in modified and chromic-acid solutions when using insoluble anodes and high current densities. This process is called hard chrome in electroplating. Three properties are improved with this type of chrome plating: wear resistance is improved, corrosion resistance is strengthened and good chemical resistance is generated. Areas of application for hard chrome include heavy-duty workpieces like brake disks or transflow balls in pipelines.
The third process at Rieger is the deposition of chrome at very high current densities. The oxygen saturation is very strong, creating a ratio of approx. 60% chromium(VI) and 40% chromium(III) oxide. A deep black layer, the black chrome, is deposited on the base metal from this reaction. This layer has similar properties to polished chrome, namely good corrosion resistance and hardness. Areas of application for black chrome can often be found in laser technology or also in the automotive industry. Black chrome is rarely offered in electroplating workshops and is therefore a special feature in our portfolio.
Each of the above-mentioned metal finishing processes is included in the Rieger portfolio and can be realised in small batches as well as in large-scale production thanks to our flexible systems. The upstream processes, such as pickling, etching, polishing or grinding, are also available in-house and are carried out by competent personnel. We can realise these surfaces on the following metals: iron, stainless steel, copper, brass, nickel, aluminium.