Iron

Iron is the main catalyst of the Haber-Bosch process, used industrially to produce ammonia from nitrogen and hydrogen. Its surface facilitates the breaking of the bonds of nitrogen molecules and favours the formation of new bonds with hydrogen. The reaction is carried out at high pressure and controlled temperature, with a catalytic formulation designed to maintain sufficient activity. The ammonia obtained is a fundamental raw material for making fertilisers and numerous chemical products.

Iron is part of the heme group of haemoglobin, the protein of red blood cells that transports oxygen from lungs to tissues. The iron atom allows haemoglobin to bind to oxygen reversibly, facilitating its capture and release during circulation. Iron also appears in muscle myoglobin and in enzymes involved in cellular processes. Its biological function depends on the organism maintaining adequate availability, as both deficiency and overload can have harmful consequences.

Numerous motors and transformers use electrical steels containing iron and designed to respond adequately to variable magnetic fields. In transformers, these materials help concentrate magnetic flux and allow energy transfer between circuits. In motors, they contribute to generating the electromagnetic forces that produce motion. Steel composition and processing are controlled to reduce energy losses, such as those associated with hysteresis and induced currents, thereby improving equipment efficiency.

When iron is exposed to water and oxygen, electrochemical reactions can occur that originate oxides and hydroxides commonly known as rust. Corrosion can advance and weaken the material, especially in humid environments or with dissolved salts. To reduce it, coatings of paint, galvanisation with zinc, cathodic protection and alloys designed to better resist certain environments are used. The most appropriate solution depends on the use, environmental conditions and expected maintenance of the item.

Iron is one of the most well-known ferromagnetic materials. Under certain conditions, its internal magnetic regions can align and produce intense magnetisation. This behaviour allows the manufacture of electromagnets, transformer cores, electric motors and numerous magnetic devices. However, magnetic properties depend on the material's structure, its temperature and the treatments it has undergone. For example, when it exceeds its Curie temperature, iron loses its ferromagnetism and behaves differently in a magnetic field.

Iron-based catalysts can be used in the Fischer-Tropsch process, which converts a mixture of carbon monoxide and hydrogen, known as synthesis gas, into hydrocarbons. These products can subsequently be processed to obtain fuels and other chemical raw materials. Iron favours the reactions that form bonds between carbon atoms, although product distribution depends on operating conditions and catalyst formulation. The technology can use synthesis gas from different raw materials.

Cast iron and steel are iron and carbon-based materials, but differ mainly in carbon content and microstructure. In general, steel contains less carbon, while cast iron has a higher proportion, which favours its fluidity when moulded. This makes many cast irons suitable for making parts with complex geometries, such as chassis and engine blocks. Steel, on the other hand, offers a wide variety of combinations of strength, ductility and toughness.