Hafnium

• Overview

  High purity hafnium, also known as crystalline hafnium, is a silver-gray metal crystal with a metallic luster. Hafnium is found in small amounts in the earth's crust and often coexists with zirconium. Hafnium has high temperature resistance, corrosion resistance, oxidation resistance, easy processing, rapid heat-absorbing and heat-releasing properties, and is used as atomic materials, alloy materials, high temperature resistant materials, electronic materials, etc.

• Physical Property

  Atomic weight: 178.49

  Melting point: 2230℃

  Density: 13.31g/cm3

  Boiling point: about 4602 ℃

• Chemical Property

  The compact hafnium metal is inactive and reacts with air to form an oxide coating, which is stable at room temperature, whereas the powdered hafnium is prone to spontaneous combustion in air. Hafnium does not react with dilute hydrochloric acid, dilute sulfuric acid, and strong alkali solutions, but is soluble in hydrofluoric acid and aqua regia.

   

  Hafnium has good corrosion resistance, not easy to be corroded by general acid-base aqueous solution, soluble in hydrofluoric acid to form fluorine complex. At high temperatures, hafnium can also combine directly with oxygen, nitrogen and other gases to form oxides and nitrides. Hafnium is relatively stable in air, and in powder form it burns very easily. Hafnium has a large thermal neutron capture cross section, hafnium has outstanding nuclear energy property, and is an indispensable rare material in the development of atomic energy industry.

• Application

  (1) Hafnium is useful because it tends to emit electrons (as in the filament used in incandescent lamps). Alloys of hafnium and tungsten or molybdenum are used as electrodes for high voltage discharge tubes. Commonly used for X-ray cathodes and tungsten filament manufacturing industries.

  (2) Pure hafnium has plasticity, easy processing, high temperature resistance and corrosion resistance, is an important material in the atomic energy industry.

  (3) Hafnium thermal neutron capture cross section is large, is an ideal neutron absorber, can be used as atomic reactor control rod and protection device.

  (4) Hafnium powder can be used as a rocket propeller.

  (5) Hafnium alloy can be used as rocket nozzles and glide reentry aircraft of the front protective layer, Hf-Ta alloy can be manufactured tool steel and resistance materials.

  (6) Hafnium is used as an additive element in heat-resistant alloys, such as tungsten, molybdenum and tantalum. HfC can be used as carbide additive because of its high hardness and melting point. The melting point of 4TaCHfC is about 4215℃, which is the highest known compound.

  (7) Hafnium can be used as an getter in many aeration systems. Hafnium getter can remove oxygen, nitrogen, etc. present in the system without the need for gases.

  (8) Hafnium is often used as an additive of hydraulic oil, to prevent the volatilization of hydraulic oil in high-risk operations, with strong anti-volatilization, so it is generally used for industrial hydraulic oil and medical hydraulic oil.