Magnesium is the lightest structural metal and the eighth most abundant element in the earth's crust. It has a hexagonal close-packed crystalline structure and good relative strength and machinability. These properties make metal highly desirable for applications where weight savings are important.

Properties of Magnesium Metal

Magnesium has a density of 1.74 g/cm3, which is about two-thirds that of aluminium and one-fourth that of steel. It has a melting point of 650°C and boiling point of 1090°C. Magnesium has good thermal conductivity, reflecting and radiating heat quickly. However, its relatively low mechanical strength limits structural applications unless alloyed. In its pure form, magnesium has a silvery appearance but rapidly develops a dull gray oxide coating when exposed to air. This thin oxide layer protects the underlying metal from further corrosion.

Production of Magnesium Metal

The two main industrial processes for Magnesium Metal production are the Pidgeon process and the electrolytic process. In the Pidgeon process, purified carnallite ore (KCl•MgCl2•6H2O) or seawater is subjected to electrolysis. Molten anhydrous salts of magnesium chloride are formed which are then reacted with ferrosilicon to produce magnesium vapor. These vapors condense to form magnesium ingots. The electrolytic process involves electrolysis of fused magnesium chloride obtained from carnallite ore. Magnesium ions are deposited at the cathode to form plates, while chlorine gas is produced at the anode. Today, over 80% of global magnesium production employs the electrolytic process due to its higher efficiency.

Applications of Magnesium in the Automotive Industry

As a lightweight metal, magnesium finds widespread use in automotive manufacturing. Engine blocks produced using sand casting of magnesium alloys provide excellent strength and heat dissipation properties while reducing weight by 35-40% compared to cast iron. Transmission casings, steering wheels and seat frames are also made from die-cast magnesium alloys for weight savings. With the push for lower vehicle emission standards, automakers are increasing use of magnesium alloys to lighten vehicle bodies and powertrains to improve fuel efficiency. For electric vehicles, magnesium allows larger battery packs within the same footprint for increased driving range.

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