Before going into details, we decided to do an overview of zirconium. This is a metallic element with the atomic number of 40 and the symbol Zr. Despite the fact that zirconium can only be found in a combined form in nature, it is very abundant on Earth, being a highly reactive element. This element belongs to the transition metals, a group of neighboring metals on the periodic table of elements which includes palladium, silver, cobalt, copper, zinc, and nickel, among many others.
However, although this element is not found in a pure form in nature, it is most commonly isolated from the mineral zircon, being malleable, highly ductile and slightly silvery in appearance. In addition to that, this metal is also very resistant to corrosion, which makes it extremely popular in metal alloys.
As you’ll see below, the zirconium can be found everywhere (in different forms), but when it was discovered for the first time? Well, for those who are interested to find out something more about this metal, you should know that the zirconium-containing mineral zircon and related minerals (jargoon, hyacinth, jacinth, ligure) were mentioned in biblical writings. As for the name, Klaproth is responable for it. While the mineral was not known to contain a new element until 1789, Klaproth analyzed a jargoon from the island of Ceylon (now Sri Lanka) and he named the new element Zirkonerde (zirconia). Zirconium metal was first obtained in an impure form in 1824 by Berzelius by heating a mixture of potassium and potassium zirconium fluoride in an iron tube.
In order to understand better what is and how we can use zirconium, we must take a look in the chemistry book. In 1925, Anton Eduard van Arkel and Jan Hendrik de Boer discovered the crystal bar process (also known as the Iodide Process), and this was the first industrial process for the commercial production of metallic zirconium. The process involves the formation and subsequent thermal decomposition of zirconium tetraiodide. Anyway, an important aspect is the price and this was the main problem of this method, but not for long because it was superseded in 1945 by the much cheaper Kroll process developed by William Justin Kroll, in which zirconium tetrachloride is reduced by magnesium:
ZrCl4 + 2 Mg → Zr + 2 MgCl2
Moving on, this metal has been used in various forms for all kind of applications including the ceramics industry, which uses zirconium in various ceramics compounds and glazes, the jewelry industry, with black zirconium being a popular choice for rings because it is durable and corrosion resistant, metallurgical furnaces, as a refractory material, and it can be sintered into a ceramic knife. In addition to that, materials fabricated from zirconium metal and its oxide (ZrO2) are used in space vehicle parts for their resistance to heat and for cladding nuclear reactor fuels.
Still, if you read this blog, then it means that you’re interested in dentistry and in this domain we can’t talk about pure zirconium, but about a derivative: zirconium dioxide, ZrO2, also referred to as zirconia. This colourless solid has exceptional fracture toughness and chemical resistance, especially in its cubic form. These properties make zirconia useful as a thermal barrier coating, although it is also a common diamond substitute, but, the most important aspect is that it is used in the dentistry, being one of the best materials for dental implants.
As the name suggest, zirconium dioxide is a compound of the zirconium and it can be obtained using the formula:
Zr + 2 H2O → ZrO2 + 2 H2