Hafnium metal is a kind of transition metal of silver gray metallic, which is in form of powder, rod, ingot, bar, target , foil, wire and piece. It exists accompany with zirconium normally. There are two crystal structures of hafnium, one is hexagonal close packing (α-type at less than 1300℃, the other is body-centered cubic (β-type). Hafnium rod is ductile metal, however it turn hard and brittle when impurities exist. It is stable in air and turn dark when igniting. Hafnium wire can ignite by match. Its property is close to zirconium. It is soluble in aqua regia and hydrofluoric acid, but doesn’t dissolve in water, dilute acid or alkali. Hafnium alloy (Ta4HfC5) is the material of highest melting point that is about 4215℃ at present.
Hafnium metal reacts with air and forms oxide layer protection. At temperature 500~750℃, the oxide layer protection lose its effect and compouds with oxygen and nitrogen ,which turns out oxides and nitrides. At temperature >800℃, Hafnium powder rapidly oxidize and forms HfO2. At temperature 1000℃, it reacts with CO and forms oxides and carbides.
|CAS No.:7440-58-6||EINECS No.:231-166-4||Molecular Formula:Hf||Molecular Weight:178.49|
|Melting Point:2227℃||Boiling Point:4602℃||Density:13.3||UN 1326 4.1/PG 2|
Hafnium metal powder can be as cathode of X-ray tube. Hafnium alloys with tungsten or molybdenum can be as electrode of high voltage discharge tube. Hf-Ta alloy is raw material for chisel tool steel and resistance material. Hf-10% Nb alloy could be as nozzle of moon shuttle. Hf-2% TaWu alloy could be as protection coating of spacecraft.
Hafnium powder can be thruster of rocket. it is a kind of additive for hydraulic oil, which prevent the volatilization when high-risk operations. It has strong resistance to volatile. It works in industrial hydraulic oil and medical hydraulic oil.
Hafnium rod owns good welding property, processability, high temperature resistance and corrosion resistance. So it is an important raw material in atomic enery industry. Thermal neutron capturing area of Hafnium rod is big, which is ideal neutron absorber. It could be used as control rod and protector in atomic reactor.
In chemical, hafnium powder can act as getter for many inflation systems. Hafnium getter could remove existed oxygen, nitrogen and other unnecessary gases. Additionaly Hafnium powder has strong volatility resistance.