Engineering Materials Classification
Engineering materials are materials used in the design, construction and operation of machines, structures and products. These materials are further classified into two main categories; metals and non-metals. Metals are solid homogeneous substances, whose atoms are arranged in a spatial arrangement of conductive electrons enabling them to bond strongly. Non-metals are substances that are not metallic in nature, that do not form a three dimensional lattice of electrons and thus necessarily cannot conduct electricity.
Metallic materials are further divided into ferrous and non-ferrous metals. Ferrous metals are metals that contain iron and have a ferromagnetic property, making them suitable for use in machines and structures that require strong magnetic fields. Examples of ferrous metals include steel, cast iron and other wrought iron products. Non-ferrous metals are metals without significant amounts of iron such as aluminum, brass, copper, lead and zinc. They are lighter and tougher than ferrous metals and often used in applications where weight and corrosion resistance are of primary importance.
Non-metallic materials are also divided into two main categories; polymers and composites. Polymers are large molecules that are made from smaller molecules which are linked together. They are generally engineered from petroleum or other hydrocarbon sources. Polymers are non-conductive and are commonly used to make items such as plastic, rubber and fiberglass. Composites are materials composed of two or more materials, where the individual components retain their individual characteristics. Composites are used extensively in the aerospace, automotive, medical and sporting goods industries to provide high strength and lightweight components.
Engineering materials are further classified as crystalline or amorphous. Crystalline materials form a regularly repeating arrangement of their atoms, while amorphous materials lack any fixed atomic arrangement. Crystalline materials are generally harder and more durable than amorphous materials but often require more complex machining operations to shape them. Examples of crystalline materials include metals, ceramics and diamond. Examples of amorphous materials include polymers, glass and soils.
Engineering materials are also divided into two main categories; natural and synthetic. Natural materials come from plants, animals and earth minerals or from waste products generated from the manufacture or use of products. Synthetic materials are man-made materials such as polymers and composites. Synthetic materials offer many advantages over natural materials, such as improved strength, durability and enhanced performance.
Engineering materials can also be classified as structural, functional or decorative. Structural materials are used to construct and support the structure in a product, such as steel in bridges and buildings. Functional materials are materials that provide a particular function in a product, such as copper in electrical components. Decorative materials provide a pleasing aesthetic, such as paint and laminates.
In summary, engineering materials are classified into two main categories; metals and non-metals. Metals are further divided into ferrous and non-ferrous metals, while non-metals are divided into polymers and composites. Engineering materials are also divided by their physical structure into crystalline and amorphous, as well as by their origin into natural and synthetic materials. Finally, engineering materials can be divided into structural, functional and decorative categories.
