Facts of the Matter
Titanium isn't rare, but properties make it valuable
TITANIUM has been touted as the metal of the 21st century. Although costly, its properties are ideal for many uses. Since the 1960s the use of titanium as a commercial product has grown significantly.
Its unusual combination of strength, resistance to heat and corrosion, and light weight make it especially useful in military applications in aircraft, naval ships, armor, missiles and spacecraft.
The lustrous putty-grey metal is up-and-coming in civilian applications not only in aviation, but in racket sports, golf clubs, bicycle frames, eyewear frames, laptop computers, jewelry and medical implants.
So what is this mysterious metal, and why has it become the "in" metal?
Titanium is a chemical element, number 22 on the periodic table. It was discovered in 1791 in impure form and named after the Titans of Greek mythology. The Titans were considered to be the personifications of the forces of nature, spawned by Gaia the Earth goddess.
Titanium has an image of being a rare material, but it is actually relatively abundant in Earth's crust. It is the ninth most abundant element, accounting for about one-half of one percent by weight.
The difficulty in manufacturing structural titanium metal, not its rarity, is responsible for titanium's relatively high cost.
The primary source of titanium is the mineral ilmenite. It is a crystalline chemical compound that contains iron and oxygen in addition to titanium.
Ilmenite forms as a primary mineral in basaltic igneous rocks and is concentrated into layers by segregation within the magma chamber.
It crystallizes out of a magma before other minerals, and the heavier crystals of ilmenite fall to the bottom of the magma chamber and collect in layers. It is these layers that when uplifted by tectonic forces constitute a rich ore body for titanium miners.
Ilmenite deposits are wide spread and include the locality from which it gets its name, Ilmen Lake in the Southern portions of the Ural Mountains.
Other deposits are in Sweden, Germany, Norway, Pakistan, Quebec and Ontario in Canada, Finland, the Eastern Shores of Australia and Brazil, Sri Lanka, China, Thailand, South Africa, India, Malaysia, Sierra Leone, New York, Wyoming, Massachusetts, California and along the eastern seaboard of the United States.
Ilmenite is also a component of moon rocks and is abundant enough in some places to have sparked interest in using it as a source of titanium, iron, and oxygen on the moon.
The metal remained a laboratory curiosity until 1946, when William Justin Kroll of Luxembourg showed that titanium could be produced commercially by reducing titanium tetrachloride, which is produced from ilmenite ore with magnesium. This method is widely used for titanium metal production today and Kroll is recognized as the father of the modern titanium industry.
Less than a decade later, after commercial alloys were devised, Lockheed built an airplane entirely out of titanium. The sleek, dark SR-71 Blackbird spy plane was the fastest, highest flying airplane ever built.
Pure titanium, although corrosion and heat resistant, is soft and weak. But alloyed with other metals it becomes the ideal "super alloy."
The most common alloy contains 6 percent aluminum and 4 percent vanadium. The atoms of these alloying metals are just the right size and electrical charge to lock the titanium atoms in place and give the alloy its amazing properties.
Because of its light weight (one half that of iron), structural strength equivalent to iron, heat and corrosion resistance, titanium was an obvious choice for aviation.
The Department of Defense provided incentives to jump-start the titanium industry because neither steel nor aluminum could satisfy the emerging need for higher strength-to-weight ratios in jet aircraft structures and engines.
The titanium alloys used in aircraft are three times stronger than steel and 45 percent lighter. Aircraft-grade titanium is eight times stronger than pure titanium.
After the impetus that was provided by the aerospace industry, titanium use took off quickly. Its ready availability triggered opportunities for new applications in other markets, such as chemical processing, medicine, power generation and more
Titanium's many desirable properties make it the metal of choice in many industries. No other metal has risen so swiftly to eminence in critical and demanding applications.
Titanium and its alloys are technically superior in a wide variety of industrial and commercial applications in architecture, sporting equipment, military hardware, watchmaking, eyewear, medical implants, dental products and more.
The physiological inertness of titanium makes it available as a replacement for bones and cartilage in a variety of surgeries.
Of the uncountable alloys that have been developed throughout the ages, few warrant even the slightest consideration for use as implant material.
The human body has poor tolerance for most products of metal corrosion. The non-corrosive noble metals (gold, silver, tantalum, platinum, and palladium) lack the chemical and mechanical properties for the construction of orthopedic tools and implants.
Corrosion of implanted metal by body fluids releases metallic ions that can interfere with bodily functions. Corrosion notwithstanding, many metals such as nickel are allergenic and even in small concentrations produce immune rejection reactions.
Titanium fills the bill, being strong, light, and corrosion resistant, and hypoallergenic as well. It is inert, resistant to corrosion and immune reaction and seems to be completely bio-compatible.
Titanium also has osteogenic properties. When used in the form of a mesh and coated with fluorophosphates or certain proteins, it stimulates bone growth.
Every year more than 2 million pounds of titanium devices are implanted in patients to replace damaged bones, joints and teeth.
Titanium is used for heart valves, pacemakers, dental implants, artificial hips and joints. It is also used in surgery equipment and wheelchairs.
In addition to these high-tech uses, titanium is an important pigment. Pure white titanium dioxide is used as a coloring agent in paint because it is extremely opaque and sun-fast. It is also used to color rubber, plastics, textiles, ink, cosmetics, leather, ceramics and paper.
Its opacity and resistance to sunlight also makes it an ideal sunscreen, although the characteristic "white nose" makes it less than ideal cosmetically for personal use.
Titanium dioxide is also used as a flux in smelting other metal oxides, as an abrasive for polishing glass and soft minerals and it is a common abrasive in non-bleaching, "whitening" toothpastes.
From its industrial and biological uses, diamond engagement, golf clubs, jewelry, sports racquets and eyeglasses, titanium is arguably the material of the future.
Richard Brill, professor of science at Honolulu Community College (honolulu.hawaii.edu/~rickb
), teaches earth and physical science and investigates life and the universe. His column is published on the first
and third Sunday of every month. E-mail questions and comments to
picks up where your high school science teacher left off. He is a professor of science at Honolulu Community College, where he teaches earth and physical science and investigates life and the universe. He can be reached by e-mail at firstname.lastname@example.org