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Zirconium Compounds
   Zirconium carbide
   Zirconium dioxide
   Zirconium(IV) hydroxide
   Zirconium nitride
Zirconium carbide ZrC
An extremely hard refractory ceramic material, commercially used in tool bits for cutting tools. It is usually processed by sintering. It has the appearance of a gray metallic powder with cubic crystal structure. It is highly corrosion resistant. Zirconium carbide reacts with water and acids and is pyrophoric.
Hafnium-free zirconium carbide and niobium carbide can be used as refractory coatings in nuclear reactors. It is also used as an abrasive, in metal cladding, in cermets, incandescent filaments and cutting tools.
Zirconium dioxide ZrO2
Sometimes known as zirconia, is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the rare mineral, baddeleyite. The high temperature cubic crystalline form, called 'cubic zirconia', is rarely, if ever, found in nature, but is synthesized in various colours for use as a gemstone and is the best-known diamond simulant.
Zirconium dioxide is one of the most studied ceramic materials. Pure ZrO2 has a monoclinic crystal structure at room temperature and transitions to tetragonal and cubic at increasing temperatures.
It is used as a refractory material, in insulation, abrasives, enamels and glazes. Stabilized zirconia is used in oxygen sensors and fuel cell membranes because it has a unique ability to allow oxygen ions to move freely through the crystal structure at high temperatures. This high ionic conductivity (and a low electronic conductivity) makes it one of the most useful electroceramics.
Zirconia is one of few compounds that actually becomes conductive at high temperatures, and more conductive, as its temperature increases. Zirconia starts out with a very high resistance at room temperature, greater than 1 trillion ohm-cm. As the temperature increases it has less than 20,000 ohm-cm at 500 degrees Celsius, to having less than 1,000 ohm-cm of resistance at 1,000 degrees Celsius. It loses nearly all of its resistance around 2,000 degrees Celsius, and becomes a very good conductor.
Zirconium(IV) hydroxide Zr(OH)4
Zirconium hydroxide is primarily used as in intermediate for the manufacture of zirconium compounds. It is used in pigments, glass and dyes.
Zirconium nitride ZrN
It is hard and refractory. It has been used recently as an alternative to titanium nitride for coating drill bits. Both coatings are supposed to keep the bit sharper and cooler during cutting. It is also used in refractories, cermets and laboratory cruibles.