Today in Science History - Quickie Quiz

What is Zirconium Used For?

A sharp-eyed student doing homework on elements found in the home was pleased to add an example of zirconium listed in the ingredients of a home product. Would you believe it? Its name may sound like something out of science fiction, but a compound of zirconium can be found used in antiperspirant deodorants. Such an unfamiliar element, right there in the bathroom cabinet! Aluminium-zirconium compounds, usually aluminium zirconium tetrachlorohydrex gly or aluminium zirconium trichlorohydrex gly, may be listed on the label of the antiperspirant you used today. Put simply, their action is to temporarily plug up the sweat glands.

How about zircons, the gemstone used to simulate diamonds in jewelry? A fanciful commercial name, or actually based on the name of zirconium? Actually, it is the other way round. It happened in 1789, when Martin Heinrich Klaproth discovered that zircon contained a new element, specifically in a sample of the mineral jargon from Ceylon. In fact, the mineral contained it as zirconium silicate (ZrSiO₄). It was decades later, in 1824, that an impure specimen of the metal was actually isolated by the Swedish chemist, Jöns Jacob Berzelius. It was not until the twentieth century, in 1914, that zirconium was prepared in a pure form, by research staff at the Philips Metal-Incandescent Lamp Works in Holland. The name zirconium, by which we now know it, in fact comes from its first discovery in the zircon mineral that had been known for centuries as a precious stone.

As a gemstone, zircon more closely resembles diamond than any other natural gem. It has a high lustre and can be cut to give an impressive sparkle. The zircon, however is less precious, and though having a good hardness, in that it is outmatched by the diamond. (The so-called cubic zirconia are man-made. They provide an inexpensive synthetic simulation of diamonds, but are unrelated to the zircon, except in containing the element ziconium in its chemical structure.)

Going back to the earlier reference to the incandescent lamp works, brings to mind the now almost disappeared household use of zirconium in the flashbulbs once used with photographic-film cameras. If you have seen the later production of glass globes stuffed with what looks like a loose fine wire wool, you have seen the element zirconium as the metal filament. Aided by an atmosphere of pressurized oxygen enclosed in the bulb, when electrically ignited, the fine zirconium wire burns in a flash of suitable colour-balanced light. In fact, when finely divided, zirconium burns giving the highest known temperature for a metal flame. In 1958, Sylvania advertised their M-25 bulb as the world’s first “zirconium filled flashbulb” which “gives picture taking light of bulbs 4 times its size!” (Earlier production used filaments of magnesium, the brightly-burning element previously used in flash powder form by the earliest photographers.)

But this element was helping illuminate before it was made into flashbulb wire. It was in the more readily obtained oxide form, zirconia, ZrO₂, that Carl Auer experimented to use it in making gas-light mantles. Although he eventually chose other rare earths for being brighter and more practical to maintain mantle form, he knew the chemical stability of zirconia even when maintained at glowing incandescent temperatures.

This property of great stabilty when heated is also the reason zirconia is used to make laboratory and foundry crucibles, which can enable melting of superalloys and precious metals without the contamination that can result with less expensive materials. Zirconia crucibles also have excellent erosion resistance during melt cycles. For this same reason, it is an excellent material to line furnaces.

The strength of zirconia is also used in making dental crowns. And the corrosion-resistance of the metal is

Zirconium is incorporated in making some superconductive magnets (alloyed with niobium)..

Because of its corrosion resistance, zirconium is used in pumps and valves in the chemical industry.

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Nature bears long with those who wrong her. She is patient under abuse. But when abuse has gone too far, when the time of reckoning finally comes, she is equally slow to be appeased and to turn away her wrath. (1882) -- Nathaniel Egleston, who was writing then about deforestation, but speaks equally well about the danger of climate change today.

Carl Sagan: In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. (1987) ...(more by Sagan)

Albert Einstein: I used to wonder how it comes about that the electron is negative. Negative-positive—these are perfectly symmetric in physics. There is no reason whatever to prefer one to the other. Then why is the electron negative? I thought about this for a long time and at last all I could think was “It won the fight!” ...(more by Einstein)

Richard Feynman: It is the facts that matter, not the proofs. Physics can progress without the proofs, but we can't go on without the facts ... if the facts are right, then the proofs are a matter of playing around with the algebra correctly. ...(more by Feynman)