My five-year-old son has a neoprene wetsuit with the word ‘titanium’ pasted across the arm. Like so many materials with high-grade properties titanium, when it is applied to consumer facing products, fits into our modern day obsession with ‘advanced materials’, which sometimes goes just a little bit too far. The ‘advanced’ profile of titanium has grown since its commercial introduction in the 1950s due to its use in high-tech applications that exploit its incredibly high strength-to-weight ratio.
Discovered by the British chemist Reverend William Gregor in 1791, titanium is named after the Greek god Titan, ‘the incarnation of natural strength’. It is the ninth most abundant element on earth and has the highest strength-to-weight ratio of any metal – titanium is as strong as most steels and less than half the weight. It has been found in meteorites and it is believed to be present in the sun as well, so it comes as no surprise that titanium has excellent resistance to corrosion, a quality that accounts for its use in the aerospace, automotive and marine industries. Titanium is one of the few metals that is allowed to be used inside the body, a group that includes stainless steel, titanium-aluminium alloy, platinum and cobaltchromium alloy.
Nearly all of the titanium ore extracted is made into white pigment, which is used in a huge range of products from paper to toothpaste.
Image: Leica M9 Titanium
•Exceptional strength-to-weight ratio
•High corrosion resistance
•Biocompatible
•Poor thermal conductivity
•Non-magnetic
•Ductile
•Low electrical conductor
•High temperature resistance, 1660ºC (3020ºF)
•Recyclable
Sources
South Africa and Australia are the two biggest producers.
Cost
£13.40-17.90 ($21-28) per kg. Although titanium is an abundant element, it is costly to process into a metal form.
Sustainability issues
The main issue with extracting titanium is that, like most metals, it is energy intensive, which raises the cost. Although there is no major recycling stream it can be recycled. Estimates by the US Geological Survey put global production in 2011 at 6,700,000 tons, with current reserves at 690,000,000 tons.
Production
As with most metals, titanium can be hot and cold formed on standard machines; however, due to its low ductility at room temperature it is difficult to work into tight corners in sheet form. Also due to its low elasticity, forming in titanium needs to be compensated for due to its tendency to spring back. Both these issues can be addressed by forming titanium at elevated temperatures. Although not easy, it can also be welded.
Typical applications
Around 95% of titanium extracted goes into the production of titanium dioxide pigment, with less than the remaining 5% being used in metal form. It is used to replace joints in the human body, in aircraft bodies, in turbines, as casings for consumer electronics and in buildings (the Frank Gehry-designed MOMA building in Bilbao is covered with titanium). Titanium nitride coatings are often used to protect blades and retain sharp edges in various cutters, drill bits and shaving blades. In this application it is a gold colour, in contrast to its natural dark grey.
Derivatives
There are many grades of titanium based on various alloys and also four grades of pure titanium, below are some of the most widely used:
–Nitinol (nickel-titanium)
–Beta C (titanium, vanadium, chromium, other metals)
–Medical-grade titanium (titanium, aluminium, vanadium)
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–Heaviest strength-to-weight ratio of all metals –Corrosion resistant –Biocompatible –Recyclable |
–High production costs –Difficult to cold work –Energy intensive to produce |