Zirconium

Zirconium is a chemical element that is classified as a transition metal and known by the chemical symbol Zr. It is greyish-white and lustrous metal. The powdered form is considered an extreme fire hazard, but not the solid form. It is found mainly in Australia, and has a number of uses in industry. Cubic zirconia, a synthetic diamond, and probably the most well-known use of Zirconium, is quite similar in appearance to a diamond, but there are several differences between them as well, discussed later on.

Properties


Physical Properties:

Zirconium is a greyish-white lustrous metal that is solid at room temperature. Many of its compounds, like Zirconium oxide (ZrO2), are white, and Zirconium powder is black. Zirconium has a hexagonal crystal structure, and is very strong and malleable, as well as ductile. Zirconium has an atomic weight of 91.22 g/mol and a melting point of 1852 °C. It boils at 4400 °C and a density of 6.49 g.cm-3 at 20°C. It has a molar volume of 14.02 cm3, a mineral hardness of 5.0, similar to the hardness of Copper and its thermal conductivity is 22.7 W m-1 K-1. Zirconium is lighter than steel and both Zirconium’s physical and chemical properties are similar to the properties of Titanium.

Chemical Properties:

While the solid form of Zirconium is difficult to ignite, when finely divided Zirconium is exposed to air, it can spontaneously ignite; particularly at high temperatures. In fact, Zirconium powder is considered an extremely dangerous fire hazard, burning at the highest known temperature for a metal (4460 ˚C) when exposed to an oxygen atmosphere. Zirconium is considered to be non-toxic, but reacts with Potassium Nitrate and oxidizers. It is extremely resistant to heat and corrosion, but is attacked quickly by hydrofluoric acid, in even small concentrations. It also does not dissolve in acids or alkalis. When alloyed with Zinc, Zirconium becomes magnetic at temperatures below -238.1 ˚C.

Occurrence and Isolation


Despite being discovered in 1789 by Klaproth, Zirconium was not isolated until 1842 in Stockholm, Sweden by J.J. Berzelius. It is found in Australia, Brazil, the USA, Russia, India, Ukraine, and South Africa. 80% of Zirconium produced is from Australia and South Africa. The top three countries of Zirconium production are, in order, Australia, South Africa and China. The Zirconium mining industry extracts and refines around 7,000 tons each year globally. Available from commercial sources, it is unusual for laboratory preparation to be needed.

Found in around 30 mineral species, with the main two being Baddeleyite and Zircon, Zirconium is also found in Zircon-rich sand that is used as an industrial material as well. It has a scarcity factor of 4.5. Australia has the largest reserve base of Zirconium and is the largest producer. The amount of Zirconium in the earth’s crust is around 0.013% while the amount in the oceans is about 2.6×10-9%. Because Zirconium reacts with water, it does not naturally occur in its metallic form.

Zirconium, sometimes produced as a derivative of titanium mining, is generally produced from the mineral Zircon. The most common method for isolating Zirconium, is the same as the one used for Titanium. It involves the action of Chlorine and Carbon on baddeleyite. The result of this is Zirconium tetrachloride, which fractional distillation separates from Iron tetrachloride. This is then reduced to metallic Zirconium by removing Magnesium By excluding air, contamination of the Zirconium by Oxygen or [Nitrogen]] is prevented.

Uses
Zirconium has a number of uses in industry. It is used in high performance pumps and valves, catalytic converters, ercussion caps and furnace bricks. Zirconium dioxide is able to withstand very high temperatures, and is used in lab crucibles and the lining of furnace walls. When alloyed with steel, Zirconium acts as a hardening agent, while other alloys can be found in pipes, fittings and heat exchangers. Zirconium is also in vacuum tubes, Military explosives and lamp filaments, as well as used in making microwave filters. Zirconium, being superconductive at low temperatures, is used to form superconductive magnets. The paper and packaging industries have found that Zirconium is a good surface coating for water resistance and strength. Zirconium, because it does not absorb neutrons well, is used widely in nuclear reactors. It is used in the outer layer of fuel rods, and a commercial-sized reactor can use up to one half-million linear feet of Zirconium alloy tubing. Zirconium is used so much in nuclear reactors that nearly 90% of Zirconium produced every year is used in the nuclear reactors.

Zirconium can also be used to make certain forms of surgical equipment as well as artificial joints and limbs. Another medical use of Zirconium is its use in lotions to treat poison ivy. Zirconium uses can be found in photographic flashbulbs, making glass for television, cutters, drawing tools and sealing technology (seal rings, bearings). It is used by the glass and ceramics industries, with one of its major uses being ceramic opacification (the development of an opacity)  and foundry sands. Zirconium is probably most well-known for its use in jewelry. A form of Zircon, a compound of Zirconium, is a clear, transparent gemstone that looks very similar to a diamond and is often used in jewelry. Cubic Zirconia is a low-cost substitute for a real diamond. Another form of jewelry produced from Zirconium is Cubic Zirconium rings and earrings.

Cubic Zirconia vs. Diamonds
Because Synthetic gemstones are so realistic when compared to the real thing, an untrained eye has difficulty distinguishing the real from the fake. However, while there are similarities, there are also differences from diamonds, and there are also simple ways to tell the difference between the fakes and the authentic ones.

How to Test a Diamond:

There are several tests able to be done on the gem in question:

1) Simply to run the diamond across a piece of glass. While a true diamond will scratch the surface with no harm to itself, a cubic zirconia would be scratched, leaving no mark on the glass. However, some higher quality cubic zirconia are being made at a higher quality and may be able to leave a mark on the glass.

2) Because true diamonds are cut with facets inside, it is nearly impossible to see through one. Place your stone on a newspaper, if the print is able to be read, it is cubic zirconia.

3) Breath on your gem. Because diamonds cannot retain heat, the fog should disappear immediately. If it does not, it is a fake.

4) A possible test using ultraviolet light, called an AUV test, looks to see the amount of florescence the stone gives off. A cubic zirconia will not give off florescent color, while a true diamond would.

5) Weight can also tell you if your diamond is real. A cubic zirconia weighs up to 50% more than a diamond, and using a gram scale, you can weigh your diamond against one that is already know to be authentic. The two stone should be the same carat.

6)Another testing possibility is by using a jewelers loop. Professionals are generally the ones performing this test, but anyone with knowledge of how to use a loop can perform this test. Cubic zirconia tends to appear waxy while a diamond will look clear. Also, some cubic Zirconia actually have CZ stamped on them, which a loop would serve to reveal.

Video
7p9H0FubPv8 Discussion on Zirconium