Brass is the generic term for a range of copper-zinc alloys with differing combinations of properties, including strength, machinability, ductility, wear-resistance, hardness, colour, antimicrobial, electrical and thermal conductivity, and corrosion resistance.
Brasses set the standard by which the machinability of other materials is judged and are also available in a very wide variety of product forms and sizes to allow minimum machining to finished dimensions. Brass does not become brittle at low temperatures like mild steel.
Brass also has excellent thermal conductivity, making it a first choice for heat exchangers (radiators). Its electrical conductivity ranges from 23 to 44% that of pure copper.
These silver coloured copper-nickel-zinc alloys containing 10-20% nickel can be regarded as special brasses. In most respects they show similar corrosion characteristics to the brasses, but the higher nickel versions have superior tarnish resistance and resistance to stress corrosion cracking. They are available in all forms and are used for tableware (silver-plated to give EPNS), telecommunication components, food manufacturing equipment, jewellery, model making, tool brush anchor wire and pins, musical instruments, e.g. ‘silver bands’, flutes, test probes and contact springs.
Colours of Brass
Brasses have a range of attractive colours,red, yellow, gold, brown, bronze, silver. Brass with 1% manganese will weather to a chocolate brown colour. Nickel silvers will polish to a brilliant silver colour. Brasses are easy to shape and, with all these colours available, it is not surprising that architects and designers have used brasses to enhance the appearance of new and refurbished buildings, both inside and out.
Brass and Hygiene
Copper and brass are playing a leading role in the fight against hospital-acquired infections such as MRSA and Clostridium difficile. It has been shown that these pathogens, which can be spread by touch, will die in a few hours on copper/brass surfaces. This does not happen on stainless steel or plastic.
The brass industry throughout the world is well organised and equipped to recycle products at the end of their long lives and process scrap (swarf and offcuts). Making brass from new (virgin) copper and zinc would be uneconomical and wasteful of raw materials so new brass products are made from recycled scrap, illustrating the sustainable nature of this material. In the UK brass manufacturers use almost 100% brass scrap.
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