Zirconium combines many useful physical, mechanical, and technological properties that determine its application from medicine to nuclear power. The page contains the description of this metal: physical and chemical properties, application, grades, types of products.
Main information
Zirconium (Zr) - chemical element of the IV group of periodical system, atomic number 40, atomic weight 91.22. Glittering silver-grey refractory metal. Density - 6.506 gpcm3, melting temperature tmelt. = 1852 °С, boiling temperature tboil. = 4377 °С. It is corrosive resistant and very plastic.
In minerals Zr is always present with hafnium (Hf). The main compounds include zirconium silicate (ZrSiO4) and baddeleyite (ZrO2).
Discovery
In 1789 M. H. Klaproth, a German chemist, obtained zirconium dioxide from mineral zirconium silicate for the first time. In free form this metal was obtained in 1824 by Berzelius, a Swedish chemist. 100 years later in 1925 A. van Arkel obtained pure Zr.
Zirconium properties
Physical properties
Property
Value
Atomic number
40
Atomic weight, amu
91,22
Atomic radius, pm
160
Density, gpcm³
6,51
Molecular heat, J/(K·mole)
25,3
Heat conductivity, W/(m·K)
22,7
Melting temperature, °С
1852
Boiling temperature, °С
4377
Melting heat, kJ/mole
19,2
Vaporization heat, kJ/mole
567
Molar volume, cm³/mole
10,8
Metal group
Refractory metal
Chemical properties
Property
Value
Covalent radius, pm
145
Ion radius, pm
(+4e) 79
Electric negativity (by Pauling)
1,33
Electrode potential, V
0
Oxidation levels
0, +1, +2, +3, +4
Zirconium and alloy grades
Both pure Zr without any alloying agents and zirconium-based alloys are applied in industry.
E110, E125 - zirconium with niobium additive, with weight percentage for E110 grade - 0.90-1.10%, for E125 grade - 2.40-2.70%; supplied in form of ingots, rods, sheets, and strips.
ZrHf-20 - zirconium-hafnium alloy (Hf - 18-22%; Zr - the rest); supplied in form of ingots and rods.
TsN25TZ - zirconium-niobium-titanium alloy (Nb - 24-26%; Ti - 2.5-3.5%; Zr - the rest); supplied in form of ingots and flat bars
Advantages / drawbacks
Advantages:
has a very low thermal neutron capture cross section;
chemically stable in many hostile environments;
high melting temperature;
inert to biological tissues and fluids;
has good technological and mechanical properties - good plasticity and strength.
Drawbacks:
high cost.
Zirconium applications
Main applications of the metals:
nuclear power;
metallurgy;
medicine;
pyrotechnics;
consumer goods industry.
Zr is highly-sought in nuclear power due to several properties. Firstly, these are neutron transparency and high corrosive resistance. Zirconium practically does not absorb thermal neutrons required for a nuclear reaction. At the same time the considered metal can work under high temperatures and is stable towards corrosion. This makes it irreplaceable in producing shells of heat-producing elements and other components of the nuclear reactor core.
In metallurgy Zr serves as a steel alloying agent, is a good scavenger and nitrogen remover (reduces the amount of nitrogen (N) in steel). Its application improves the mechanical properties and machinability of steel so as increases heat resistance.
Zirconium stability towards the impact of biological environments and biocompatibility allow using it in medicine also. It is used for producing osteal, joint, and dental prostheses so as surgical tools.
Zr is also used in superconductors. It is included in the superconducting alloy (niobium - 75%, zirconium - 25%).
Contemporary industrial production offers a full range of standard blanks widely used in several spheres. Among rolled products zirconium rods, wire and pipes are used. Flat products are represented by zirconium foil, strips, sheets, flat bars and slabs. Primary raw materials include ingots that play the main role in the chain of manufacturing products from this metal.