Metals

Understanding Metals

• Metals are hard, malleable substances that can conduct heat and electricity.
• They are generally shiny, high in density and melting point, making them ideal for a variety of applications.
• Metals are classified into two main categories: Ferrous (containing iron) and Non-ferrous (not containing iron).

Types of Metals

• Ferrous metals are often magnetic and have tensile strength. They are also prone to rusting. Examples include iron and steel.
• Nonferrous metals are usually more resistant to corrosion and are not magnetic. Examples include aluminium, copper, tin, nickel, zinc, and precious metals like gold, silver, and platinum.
• Alloys are a combination of two or more metals or a metal and another element, specifically designed to provide unique properties. Examples include brass (copper and zinc) and stainless steel (iron, carbon, and chromium).

Properties of Metals

• Metals have a crystalline structure that offers high strength and stiffness.
• The ductility of metals allows them to be stretched into thin wires.
• Metals typically have high melting and boiling points due to strong metallic bonds.
• Most metals are good conductors of heat and electricity, making them useful in applications such as cooking utensils and wiring.

Applications of Metals

• Metals have extensive applications ranging from construction, transport, power generation, to kitchenware and everyday objects.
• Ferrous metals, like steel, are often used in building structures, automobiles, pipelines, and tools due to their high strength and durability.
• Non-ferrous metals like aluminium, copper and brass are used in applications that require low weight, high conductivity, or resistance to corrosion.
• Precious metals like gold, silver, and platinum are commonly used in jewellery and high-tech applications due to their desirable properties and aesthetic appeal.

Environmental Impact of Metals

• The extraction and processing of metals can pose significant environmental challenges including damage to landscapes and ecosystems due to mining.
• Toxic waste from metal production can cause water and air pollution.
• Many metals are recyclable, and recycling can significantly reduce energy use and environmental impact compared to primary production.
• Life cycle analyses can be conducted to investigate the environmental impacts of different metals from extraction to disposal.

Manufacturing Techniques

• Multiple techniques are used for shaping metals including casting, forging, rolling, and extrusion.
• Subtractive techniques such as machining, grinding, drilling can also be used.
• Joining techniques for metals include welding, brazing, soldering, and using mechanical fasteners.
• Heat treatment offers a method of altering the properties of metal to enhance its performance in specific applications.