Zirconium - Properties - Price - Applications

About Zirconium

Zirconium is a lustrous, grey-white, strong transition metal that resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium is widely used as a cladding for nuclear reactor fuels. The desired properties of these alloys are a low neutron-capture cross-section and resistance to corrosion under normal service conditions.

Summary

Element	Zirconium
Atomic number	40
Element category	Transition Metal
Phase at STP	Solid
Density	6.511 g/cm3
Ultimate Tensile Strength	330 MPa
Yield Strength	230 MPa
Young’s Modulus of Elasticity	88 GPa
Mohs Scale	5
Brinell Hardness	650 MPa
Vickers Hardness	900 MPa
Melting Point	1855 °C
Boiling Point	4377 °C
Thermal Conductivity	22.7 W/mK
Thermal Expansion Coefficient	5.7 µm/mK
Specific Heat	0.27 J/g K
Heat of Fusion	16.9 kJ/mol
Heat of Vaporization	591 kJ/mol
Electrical resistivity [nanoOhm meter]	421
Magnetic Susceptibility	N/A

Applications of Zirconium

Most zircon is used directly in high-temperature applications. This material is refractory, hard, and resistant to chemical attack. Because of these properties, zircon finds many applications, few of which are highly publicized. Its main use is as an opacifier, conferring a white, opaque appearance to ceramic materials. Zirconium and its alloys are widely used as a cladding for nuclear reactor fuels. Zirconium alloyed with niobium or tin has excellent corrosion properties. The high corrosion resistance of zirconium alloys results from the natural formation of a dense stable oxide on the surface of the metal. This film is self healing, it continues to grow slowly at temperatures up to approximately 550 °C (1020 °F), and it remains tightly adherent. The desired property of these alloys is also a low neutron-capture cross-section. The disadvantages of zirconium are low strength properties and low heat resistance, which can be eliminated, for example, by alloying with niobium.

Production and Price of Zirconium

Raw materials prices change daily. They are primarily driven by supply, demand and energy prices. In 2019, prices of pure Zirconium were at around 160 $/kg.

Approximately 900,000 tonnes of zirconium ores were mined in 1995, mostly as zircon. The production of zirconium metal requires special techniques due to the particular chemical properties of zirconium. Most Zr metal is produced from zircon (ZrSiO4) by the reduction of the zirconium chloride with magnesium metal in the Kroll process. The key feature of the Kroll process is reduction of zirconium chloride to metallic zirconium by magnesium. Commercial non-nuclear grade zirconium typically contains 1–5% of hafnium, whose neutron absorption cross-section is 600x that of zirconium. Hafnium must therefore be almost entirely removed (reduced to < 0.02% of the alloy) for reactor applications. In terms of cost, these alloys are also often the materials of choice for heat exchangers, and piping systems for the chemical-processing and nuclear industries. Zirconium is a by-product of the mining and processing of the titanium minerals, as well as tin mining. From 2003 to 2007, while prices for the mineral zircon steadily increased from $360 to $840 per tonne, the price for unwrought zirconium metal decreased from $39,900 to $22,700 per ton. Zirconium metal is much more expensive than zircon because the reduction processes are costly. All costs significantly vary with certain purity.

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Mechanical Properties of Zirconium

Strength of Zirconium

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. In designing structures and machines, it is important to consider these factors, in order that the material selected will have adequate strength to resist applied loads or forces and retain its original shape. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

For tensile stress, the capacity of a material or structure to withstand loads tending to elongate is known as ultimate tensile strength (UTS). Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins.

Ultimate Tensile Strength of Zirconium

Ultimate tensile strength of Zirconium is 330 MPa.

Yield Strength of Zirconium

Yield strength of Zirconium is 230 MPa.

Modulus of Elasticity of Zirconium

The Young’s modulus of elasticity of Zirconium is 230 MPa.

Hardness of Zirconium

In materials science, hardness is the ability to withstand surface indentation (localized plastic deformation) and scratching. Brinell hardness test is one of indentation hardness tests, that has been developed for hardness testing. In Brinell tests, a hard, spherical indenter is forced under a specific load into the surface of the metal to be tested.

Brinell hardness of Zirconium is approximately 650 MPa.

The Vickers hardness test method was developed by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers hardness test method can be also used as a microhardness test method, which is mostly used for small parts, thin sections, or case depth work.

Vickers hardness of Zirconium is approximately 900 MPa.

Scratch hardness is the measure of how resistant a sample is to permanent plastic deformation due to friction from a sharp object. The most common scale for this qualitative test is Mohs scale, which is used in mineralogy. The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly.

Zirconium is has a hardness of approximately 5.

Zirconium – Crystal Structure

A possible crystal structure of Zirconium is hexagonal close-packed structure.

In metals, and in many other solids, the atoms are arranged in regular arrays called crystals. A crystal lattice is a repeating pattern of mathematical points that extends throughout space. The forces of chemical bonding causes this repetition. It is this repeated pattern which control properties like strength, ductility, density, conductivity (property of conducting or transmitting heat, electricity, etc.), and shape. There are 14 general types of such patterns known as Bravais lattices.

Crystal Structure of Zirconium

Strength of Elements

Elasticity of Elements

Hardness of Elements

Thermal Properties of Zirconium

Zirconium – Melting Point and Boiling Point

Melting point of Zirconium is 1855°C.

Boiling point of Zirconium is 4377°C.

Note that, these points are associated with the standard atmospheric pressure.

Zirconium – Thermal Conductivity

Thermal conductivity of Zirconium is 22.7 W/(m·K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

Coefficient of Thermal Expansion of Zirconium

Linear thermal expansion coefficient of Zirconium is 5.7 µm/(m·K)

Thermal expansion is generally the tendency of matter to change its dimensions in response to a change in temperature. It is usually expressed as a fractional change in length or volume per unit temperature change.

Zirconium – Specific Heat, Latent Heat of Fusion, Latent Heat of Vaporization

Specific heat of Zirconium is 0.27 J/g K.

Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. Heat capacity C has the unit of energy per degree or energy per kelvin. When expressing the same phenomenon as an intensive property, the heat capacity is divided by the amount of substance, mass, or volume, thus the quantity is independent of the size or extent of the sample.

Latent Heat of Fusion of Zirconium is 16.9 kJ/mol.

Latent Heat of Vaporization of Zirconium is 591 kJ/mol.

Latent heat is the amount of heat added to or removed from a substance to produce a change in phase. This energy breaks down the intermolecular attractive forces, and also must provide the energy necessary to expand the gas (the pΔV work). When latent heat is added, no temperature change occurs. The enthalpy of vaporization is a function of the pressure at which that transformation takes place.

Melting Point of Elements

Thermal Conductivity of Elements

Thermal Expansion of Elements

Heat Capacity of Elements

Heat of Fusion of Elements

Heat of Vaporization of Elements

Zirconium – Electrical Resistivity – Magnetic Susceptibility

Electrical property refers to the response of a material to an applied electric field. One of the principal characteristics of materials is their ability (or lack of ability) to conduct electrical current. Indeed, materials are classified by this property, that is, they are divided into conductors, semiconductors, and nonconductors.

Electrical Resistivity of Zirconium

Electrical resistivity of Zirconium is 421 nΩ⋅m.

Electrical conductivity and its converse, electrical resistivity, is a fundamental property of a material that quantifies how Zirconium conducts the flow of electric current. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity.

Magnetic Susceptibility of Zirconium

Magnetic susceptibility of Zirconium is N/A.

In electromagnetism, magnetic susceptibility is the measure of the magnetization of a substance. Magnetic susceptibility is a dimensionless proportionality factor that indicates the degree of magnetization of Zirconium in response to an applied magnetic field.