Cadmium is a soft, bluish-white metal with an atomic number of 48 and the chemical symbol Cd. It is part of group 12 on the periodic table and is one of the three, along with zinc and mercury, stable metals in this section. It has a low melting point compared to the transition metals and is mainly found as part of zinc ores. Cadmium was discovered in 1817 by two German scientists, Stromeyer and Hermann. In certain forms this element is toxic causing death at high levels. Due to this fact, the uses of cadmium are gradually decreasing as new and safer materials are found. This article will detail how cadmium is used in the world today.
Uses of cadmium
- The main use of cadmium was in batteries, in particular rechargeable nickel plated batteries. Nickel-cadmium batteries have a charge of 1.2 V. The use of cadmium in batteries and other electronics has been banned by the European Union due to its toxicity and it is expected they will eventually be banned worldwide.
- Cadmium is also used in electroplating in the aircraft industry. Cadmium is able to resist corrosion when applied to steel plating.
- Cadmium is used in the nuclear fission process as a barrier to control neutrons. It is used as part of an alloy with silver and indium and makes up 5% of the total alloy.
- Cadmium oxide is used in the production of televisions. It is used in black and white phosphors and also in blue and green phosphors in television tubes.
- The coating of photocopier drums is made from cadmium sulphide.
- Cadmium sulphite is also used as a yellow pigment in paints. Cadmium selenide is used as a red pigment in paints. Cadmium salts create bright, brilliant colours that last for long periods of time before showing any signs of fading. It is recommended that gloves or a barrier cream be used when painting with these pigments as cadmium is toxic. This paint is commonly used on brightly coloured buses and trains.
- Cadmium is used in solder and bearing alloys. It has the ability to resist fatigue and friction.
- When combined with helium, cadmium makes an effective laser emitting blue-ultraviolet laser light. These lasers are used in fluorescence microscopes.
- Colloidal solutions with cadmium are used in the imaging of biological tissue and solutions under a fluorescence microscope.
- Cadmium is sensitive to infrared light and is used in applications such as infrared detectors and switches like those found in remote controls. It is also used in solar cells.