Hafnium Rod, Wire, Bar and Tube

In the early XXth century, Niels Bohr discharged that the last rare-earth metal must be element with number 72 - zirconium analog. In 1923, George de Hevesy and Dirk Coster found out new elements with properties that were predicted by Bohr in Greenland and Norse zircons. It was named in honor of Latin ancient name of Copenhagen city - Hafnia. World's output of hafnium constitutes 70 tones in a year that is proportional to zirconium output volume. The richest hafnium deposits are located in Australia and RSA. Cost of 99% hafnium constitutes about 780 dollars per one kilogram.

Physical features

Hafnium (Hf) is hard refractory silver-white metal. It possesses close-packed hexagonal structure of crystal lattice with volume weight of 13.31 g/cm3.Valence is +4, +3, 1. Boiling temperature is 4603 °C. Melting point is 2233 °C. Thermal-neutron capture cross-section is about 100 barns, which is three times larger than in zirconium. That is why zirconium used in nuclear reactors must not contain hafnium. Natural isotope ¹⁷⁴ Hf possesses low α- activity with half-life period of 2x10¹⁵ years.

Application

Nuclear energetics Neutron capture capability determines its application in the capacity of special ceramics, glass, antilife plungers of nuclear reactors, (boride, oxide, oxicarbide, lithium khanate, carbide, dysprosium hafnate). Alloy W-Hf-Ta is the best material for vapour-phase engine fuel supply.

Optics Due to its heat resistance and high deflection level, HfF₄ and HfO₂ are applied in manufacture of multilayer mirrors and X-ray astronomical mirror.

Radioelectronics A low work of electron liberation allows manufacturing the cathodes of powerful electron-beam guns, radio tubes, effective electric power generators.

Electrical engineering Along with heat resistance, low work of electron liberation gives a possibility to use Hf in manufacture of electrodes that are intended for argon welding. It can also b used in CO₂ atmosphere and low-carbon steel where electrodes of such type are four times stronger than tungsten. It is worth noting a high economical effect of Ta-Hf alloy using for electrodes of air-plasma and oxygen-flaming metal cutting. Alloy contains: 77% of Hf, 20% of Ta, 2% of W, 0,5% of Ag, 0,1% of Cs, 0,4% of Cr. It has nine fold operational life in comparison to pure hafnium.

Alloys

Addition of Hf (1%) to aluminium makes extra-hard alloy with crystallite size of 40−50 millimicron. It has good vibration strength, high ultimate strength at shearing, rupture in torsion, tension. Alloying with Hf notably hardens different cobalt alloys that are requested in petroleum refining industry and industrial chemistry. Hafnium boride and carbide with melting point of 3250 °C are used in the capacity of super wearing resistant covering and in composition of extra-hard alloys.

One of the most refractory materials is HfC with melting point of 3890 °C. This alloy is indispensable in constructions of atomic vapor-phase reactors and in manufacture of rocket nozzles, Alloy of nickel + HfB₂ is used as exceptionally wearing resistant composite coating. Alloy of TaC (80%) and HfC (20%) is considered to be the most heat resistant alloy with melting point of 4216 °C.

Mechanical engineering Titanium alloys doped with hafnium are used in manufacture of ship engine parts. Hafnium alloying of nickel increases corrosion resistance and strength. It also strengthens welding seam and improves weldability. Addition of Hf to tantalum sharply increases resistance to corrosion in air due to forming of composite oxide film on a surface that is very resistant to heat shock. Due to this, there were invented the indispensable alloys for rocket engineering (gas nozzles, deflectors that contain up to 20% of Hf).

Other application spheres

Alloys that include hafnium and rare-earth elements such as terbium, samarium are the basis of super-powerful permanent magnets. Dielectrics with high diectrictric penetrability on the HfO₂ basis supplant the paradigmatic silicon oxide in microelectronics allowing reaching much higher data density. There is also known hafnium silicide as a dielectric with high dielectric permeability. Scandium alloys are applied in microelectronics for the purpose of obtaining resistance films with unique properties.

Percentage composition of hafnium iodide

Perspective application spheres

Hf-178m2 is after-product of nuclear energetics (in NPP, they are absorbing exhausted hafnium cores). This isotope with half-life period of 31 years contains energy surplus which can be released with a help of nucleus radiation processing. Energy that is included in one gram of Hf-178m2 equals to 50 kilograms of tritol. This makes possible its application or purpose of combat compact laser pumping in the capacity of controlled gamma-ray source (for example in flaw detection in the capacity of intensive energy source for transport.