Rhodium electroplating

Miscellaneous. Ruthenium dioxide-based thick-film resistors have been used as secondary thermometers below I K (92). Ruthenium dioxide-coated anodes ate the most widely used anode for chlorine production (93). Ruthenium(IV) oxide and other compounds ate used in the electronics industry as resistor material in apphcations where thick-film technology is used to print electrical circuits (94) (see Electronic materials). Ruthenium electroplate has similar properties to those of rhodium, but is much less expensive. Electrolytes used for mthenium electroplating (95) include [Ru2Clg(OH2)2N] Na2[Ru(N02)4(N0)0H] [13859-66-0] and (NH 2P uds(NO)] [13820-58-1], Several photocatalytic cycles that generate... 

Aqueous Electrodeposition. The theory of electro deposition is well known (see Electroplating). Of the numerous metals used in electro deposition, only 10 have been reduced to large-scale commercial practice. The most commonly plated metals are chromium, nickel, copper, zinc, rhodium, silver, cadmium, tin, and gold, followed by the less frequendy plated metals iron, cesium, platinum, and palladium, and the infrequendy plated metals indium, mthenium, and rhenium. Of these, only platinum, rhodium, iddium, and rhenium are refractory. 

The most widely used methods for the application of coatings of gold, silver and the platinum group metals (platinum, palladium, rhodium, iridium, ruthenium, osmium) to base metals are mechanical cladding and electroplating. 

Rhodium is one of the six platinum transition elements that include Ru, Rh, Pd, Os, Ir, and Pt. Of these metals, rhodium has the highest electrical and thermal conductivity. Although a relatively scarce metal, rhodium makes an excellent electroplated surface that is hard, wears well, and is permanently bright— ideal for plating the reflectors in automobile headlights. 

Uses. Electroplating manufacture of rhodium-platinum alloys manufacture of high-reflectivity mirrors... 

Rhodium is used as an alloy with platinum, and as a catalyst. It is also used as a corrosion-resistant electroplate for protecting silverware from tarnishing, for making high-reflectivity mirrors for cinema projectors, and searchlights. It can be used as a catalyst for chemical reactions, and in jewelry. In fact, rhodium is a very common plating for inexpensive jewelry because it is extremely shiny and tarnish resistant. It is actually a very expensive metal however, only need a microscopically thin layer is needed. 

OTHER COMMENTS soluble rhodium salts may be used in electroplating baths for finishing scientific instruments, radio equipment, jewelry, and camera fittings has been utilized in laboratory research. 

The autocatalyst is the main appheation for rhodium now (Fig. 1) [1, 2]. Electrodeposition of rhodium is also widely used both in corrosion prevention and in the decorative field [46,61,85]. Details about the progress in electroplating baths for rhodium have been summarized elsewhere [56-58, 61, 85]. 

It should be mentioned here that the composition of the electrolyte solution used in these in situ STM studies of the electrochemical deposition of noble metals (platinum, palladium, rhodium and ruthenium) are quite different from those used in the real electroplating industry [56-58]. Although some experimental conditions (temperature, concentration) may be difficult for the in situ STM measurements, electrodeposition in a practical electrolyte bath should provide more information both in application and in fundamental fields. 

Jewelry and eyeglasses are electroplated with rhodium to prevent tarnishing. 

The electroplating baths contain a platinum salt such as the so-called P-salt, the hexachloro-platinic add, or the sodium hexachloroplatinate (IV). The electrocatalytic coating consists of platinum and rhodium present in their metallic forms. However, both rhodium and platinum have high chlorine overvoltage (e.g. 300 mV for Rh and 486 mV for Pt at 10 kA.m" ) and exhibit a slight corrosion with the rate depending on the electrolyte and the nature of bath impurities (e.g., CT, F, organics). 

Two types of specular references are used as standard materials. The first type, called first-surface mirrors, reflect incident radiation off the primary contact surface. These are typically vapor deposited or electroplated metals—gold, silver, rhodium, or aluminium on metallic or nonmetaUic (glass, quartz, or some other material that is thermally and mechanically stable) substrates. An important consideration is the flatness of the surface to be coated. The material must have minimal roughness and the surface must be as flat as possible to avoid measurement error. 

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