Titanium is the perfect metal to make replacement human body parts
Titanium material is expensive and can be problematic when it comes to traditional processing technologies. For example, its high melting point (1,670℃, much higher than steel alloys) is a challenge.
The relatively low-cost precision of 3D printing is therefore a game-changer for titanium. 3D printing is where an object is built layer by layer and designers can create amazing shapes.
This allows the production of complex shapes such as replacement parts of a jaw bone, heel, hip, dental implants, or cranioplasty plates in surgery. It can also be used to make golf clubs and aircraft components.
The CSIRO is working with industry to develop new technologies in 3D printing using titanium. (It even made a dragon out of titanium.)
Advances in 3D printing are opening up new avenues to further improve the function of customised bodypart implants made of titanium.
Such implants can be designed to be porous, making them lighter but allowing blood, nutrients and nerves to pass through and can even promote bone in-growth.
Safe in the body
Titanium is considered the most biocompatible metal – not harmful or toxic to living tissue – due to its resistance to corrosion from bodily fluids. This ability to withstand the harsh bodily environment is a result of the protective oxide film that forms naturally in the presence of oxygen.
Its ability to physically bond with bone also gives titanium an advantage over other materials that require the use of an adhesive to remain attached. Titanium implants last longer, and much larger forces are required to break the bonds that join them to the body compared with their alternatives.
Titanium alloys commonly used in load-bearing implants are significantly less stiff – and closer in performance to human bone – than stainless steel or cobalt-based alloys.
Titanium weighs about half as much as steel but is 30% stronger, which makes it ideally suited to the aerospace industry where every gram matters.
In the late 1940s the US government helped to get production of titanium going as it could see its potential for “aircraft, missiles, spacecraft, and other military purposes”.
Titanium has increasingly become the buy-to-fly material for aircraft designers striving to develop faster, lighter and more efficient aircraft.
About 39% of the US Air Force’s F22 Raptor, one of the most advanced fighter aircraft in the world, is made of titanium.
Civil aviation moved in the same direction with Boeing’s new 787 Dreamliner made of 15% titanium, significantly more than previous models.
Two key areas where titanium is used in airliners is in their landing gear and jet engines. Landing gear needs to withstand the massive amounts of force exerted on it every time a plane hits a runway.
Titanium’s toughness means it can absorb the huge amounts of energy expelled when a plane lands without ever weakening.
Titanium’s heat resistance means it can be used inside modern jet engines, where temperatures can reach 800℃. Steel begins to soften at around 400℃ but titanium can withstand the intense heat of a jet engine without losing its strength.