Zirconium

Zirconium is a lustrous, grey-white, strong transition metal that is highly resistant to corrosion. It is mainly found in the minerals zircon and baddeleyite. Due to its resistance to heat and corrosion, zirconium is used in various industrial components. It also has applications in ceramics and foundry equipment. Zirconium alloys, particularly those with niobium, are valuable in nuclear technology due to their low neutron-capture cross-section.

Chemical Composition of Zirconium

Zirconium's chemical composition includes:

Zirconium (Zr): More than 90% of the composition offering good corrosion protection as well as strength.
Hafnium (Hf): Up to 2-3%: alters neutron absorption characteristics, sometimes machined out for nuclear uses.
Oxygen (O): Existing in the ppm level affecting mechanical characteristics and corrosion protection.
Iron (Fe), Chromium (Cr), Nickel (Ni): As deoxidisers, improving strength and corrosion resistance, in small amounts as impurities.
Silicon (Si): Residues from the presence of impurities or during the process of refining.

These elements play a role in making zirconium have high melting point, corrosion resistance and its ability to be used in high temperature and nuclear industries.

Properties of Zirconium

Following are properties of Zirconium:

Corrosion Resistance: Zirconium has very low rates of corrosion and this is further reduced when it is in contact with acids and alkalis.
High Melting Point: Zirconium has a high melting point of 1855°C (3371°F) and for this reason, it is used in high temperature applications.
Strength: Zirconium is known to have good mechanical properties and it is also very resistant to wear and tear.
Low Neutron-Capture Cross-Section: Zirconium is preferred for use in nuclear reactors because it has a very low neutron capture cross-section.
Biocompatibility: Zirconium is non-toxic and hence can be used in production of medical implants and surgical tools.
Thermal Conductivity: Zirconium is moderately conductive to heat and, therefore, finds application in heat transfer applications.
Electrical Conductivity: Zirconium also has acceptable electrical conductivity which makes it suitable for some electronics.
Density: Zirconium has a density of 6. 52 g/cm³ which is relatively low for a metal and helps in lightweight applications.
Oxide Formation: The element zirconium develops a passive oxide film which increases its corrosion ability.

These properties make Zirconium useful in the following applications.

Types of Zirconium

Following are the types of Zirconium materials :

Commercial-Grade Zirconium: Hafnium and other impurities used in chemical processing and industrial applications, small amounts present.
Nuclear-Grade Zirconium: Purified to remove hafnium because it is a neutron-absorber that is undesirable for nuclear reactor applications.
Zirconium Alloys: When combined with other metals such as niobium, tin, chromium, it is used in aerospace and biomedical applications.
Zirconium Dioxide (Zirconia): Ceramic zirconium oxide, applied in dental implants, fuel cells, and ceramic knives because of its high hardness and heat resistance.
Zirconium Sponge: A type of zircon used as a form of zirconium metal in nuclear and aerospace industries as an intermediate product.
Zircaloy: A family of zirconium based alloys with tin, iron, chromium and nickel, used extensively in nuclear reactors for fuel cladding and structural parts.

These different forms and alloys of zirconium serve different industries as indicated below.

Manufacturing Process of Zirconium

The manufacturing process of zirconium involves the following steps:

Mining and Extraction: Zirconium is mainly produced from zircon and baddeleyite ores by physical processes such as gravity concentration, froth flotation, and magnetic separation.
Ore Concentration: The extracted ore is then subjected to concentration in order to increase the proportion of zirconium to the other minerals.
Conversion to Zirconium Tetrachloride (ZrCl4): The concentrated ore is treated with chlorine gas and carbon to form zirconium tetrachloride which can be purified by distillation.
Reduction to Metallic Zirconium: The Kroll process involves the reduction of zirconium tetrachloride by magnesium at high temperatures to give metallic zirconium and magnesium chloride to give a porous product referred to as zirconium sponge.
Sponge Purification: To remove magnesium and magnesium chloride that may still be present in the zirconium sponge, the sponge is leached in acid.
Melting and Alloying: The purified zirconium sponge is melted in an arc furnace and is cast into ingots. Other metals can be added to make an alloy of the required characteristic.
Forming and Shaping: The zirconium ingots can be shaped by casting, forging, rolling or extrusion to get the final form. The products are then machined and surface treated to improve properties such as the corrosion resistance and then tested for quality.

This process makes it possible to obtain a high purity of zirconium that can be used in several industries.

Advantages of Zirconium

Here are some unique benefits of zirconium:

Non-Magnetic: Zirconium is non-magnetic, therefore is applied where there is a need to avoid interference with magnetic fields.
Good Fabricability: Zirconium is relatively easy to work and can be rolled into sheets, drawn into wires and extruded into tubes in the same manner as other metals.
Lightweight: Nonetheless, the density of zirconium is low and this is useful in applications where weight is a critical factor, for example in aerospace and transport industries.
Refractory Properties: Zirconium has very high melting and high strength at high temperatures, making it ideal for use in applications such as in furnace linings.
Aesthetic Appeal: Zirconium has a silver-grey metallic lustre, and although it is not generally used for ornaments, it can be employed in the production of jewellery and other decorative items.
Chemical Inertness: This is because zirconium is chemically stable in many chemical situations and therefore used in many industrial processes.

These benefits make Zirconium to be useful in many fields of application.

Applications of Zirconium:

Here are some key applications of Zirconium:

Nuclear Reactors: Zirconium is widely used in nuclear reactors due to its low neutron-capture cross-section and high corrosion resistance, making it ideal for fuel cladding and structural components.
Chemical Processing Equipment: Due to its excellent resistance to corrosion, zirconium is used in the manufacture of chemical processing equipment, such as reactors, heat exchangers, and piping systems.
Aerospace Industry: The high strength-to-weight ratio and thermal stability of zirconium make it valuable for aerospace applications, including jet engines and spacecraft components.
Medical Implants: Zirconium's biocompatibility and resistance to body fluids make it suitable for medical implants, such as joint replacements and dental implants.
Surgical Instruments: The durability and corrosion resistance of zirconium are beneficial for surgical instruments that require precision and longevity.
Jewelry: With its lustrous appearance and resistance to tarnish, zirconium is used in the jewelry industry to create durable and attractive pieces.
Hydrogen Storage: Zirconium's ability to absorb hydrogen makes it useful in hydrogen storage and purification systems.
Electronics: Due to its electrical conductivity and stability, zirconium is employed in certain electronic components and devices.

These diverse applications highlight the versatility and valuable properties of zirconium across various industries.