Zirconium and zirconium alloy Overview and Applications

Zirconium is a very strong, malleable, ductile, lustrous silver-gray metal with a melting point of 1852.0°C. At ordinary temperatures it has a hexagonal close-packed crystalline structure. Its chemical and physical properties are similar to those of titanium, the element above it in Group 4 of the periodic table. Zirconium is extremely resistant to heat and corrosion. Low neutron-capture cross-section and good resistance to corrosion under normal service conditions of Zr alloys make them useful in nuclear energy applications. In powder form, zirconium is highly flammable, but the solid form is far less prone to ignition. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial grade zirconium contains 1 to 3% hafnium.

The purified metal is primarily used in the nuclear industry to form outer layers of fuel rods in nuclear reactors. Zirconium is also used in corrosion-resistant piping, heat exchangers, and lamp filaments. Alloys of zirconium are used for medical implants and prosthetic devices. Its alloy with niobium is superconductive at low temperatures. Also, zirconium-aluminum alloys are used to make high-strength bicycle frames and lacrosse sticks.

This metal also boasts many other uses, such as in photographic flashbulbs and surgical instruments, in the removal of residual gases from electronic vacuum tubes, and as a hardening agent in alloys, especially in steel. This metal is mainly used in nuclear reactors. It is employed in tubes for cladding uranium oxide fuel. The reason why It is well suited for this purpose is because it is corrosion-resistant and will not easily absorb thermal neutrons. It is specially purified without hafnium, which absorbs neutrons much more readily. It is usually alloyed with other metals to make it more corrosion-resistant for these uses.

Zirconium is very resistant to corrosion by many common acids and alkalis and by sea water. It is therefore used extensively in the chemical industry where corrosive agents are employed. This metal is used as an alloying agent in steel and is employed for making surgical appliances as well. Zirconium/niobium alloys are used to make super conductor magnets. Alloys with zinc become magnetic at temperatures below 35 K. Zirconium is used as a "getter" in vacuum tubes, in flash bulbs for photography, in explosive primers, and in lamp filaments.

Zirconium alloys can be machined by conventional methods, but they have a tendency to gall and work harden during machining. Consequently, tools with clearance angles higher than normal are needed to penetrate previously work-hardened surfaces. Zirconium has better weldability than some of construction metals including some alloy steels and aluminum alloys that are more common. Low distortion during welding stems from a low coefficient of thermal expansion. Welding zirconium requires proper shielding because of the metal’s reactivity to gases at welding temperatures. Welding without proper shielding (argon or helium) causes absorption of oxygen, hydrogen, and nitrogen from the atmosphere, resulting in brittle welds.

As a result of its exceptional corrosion resistance, zirconium is used extensively in corrosive environments in the chemical industry where zirconium alloys can be found in pipes, fittings and heat exchangers.

Zircon (zirconium silicate, ZrSiO4) is a natural gemstone and synthetic cubic zirconia (zirconium dioxide, ZrO2) is produced as a low-cost substitute for diamond.

Zirconium-based catalysts are used in amination, hydrogenation, isomerization and oxidation reactions.

Lithium zirconate can be used to absorb carbon dioxide. The reaction is reversible so the carbon dioxide can be released in well-chosen location and the lithium zirconate can be used again. This application may be useful in addressing environmental concerns about the release of carbon dioxide into the atmosphere.

Zirconium resists corrosion, and hence, it is used as an alloying agent in materials that often come in contact with corrosive agents. Some of these materials are used as surgical appliances, vacuum tube getters, and filaments or explosive primers. Being heat-resistant, the alloys of zirconium are employed in space vehicles. Its biocompatibility, appearance, and strength make oxidized zirconium useful for dentists to prepare the crowning of the teeth.

Other important uses include its use in the core structural material of a nuclear reactor. Here, this metal is used because of its strength and thermal neutron absorption, which allows the structural material to absorb the thermal neutrons. If you lower the thermal neutron absorption, then the efficiency of the nuclear reactor increases.