PDT 153 Materials Structure And Properties Chapter 1: Introduction to Materials Science and Engineering Prepared by: Dr. Tan Soo Jin

What are Materials Materials may be defined as substance of which something is composed or made. We obtain materials from earth crust and atmosphere. Examples: Silicon and Iron constitute 27.72 and 5.00 percentage of weight of earths crust respectively. Nitrogen and Oxygen constitute 78.08 and 20.95 percentage of dry air by volume respectively.

Historical Perspective The earliest humans had access to only a very limited number of materials, those that occur naturally: stone, wood, clay, skins, and so on. With time, they discovered techniques to produce new materials: pottery and various metals. When time passed, they discovered the properties of a material could be altered by heat treatments and by the addition of other substances. The development of many technologies that make our existence so comfortable has been intimately associated with the accessibility of suitable materials.

Materials Science and Engineering (MSE) Materials science concerned with basic knowledge about internal structure, properties, and processing of materials. Materials engineering concerned with the use of fundamental and applied knowledge of materials so that the materials can be converted into products needed or desired by society.

Materials Engineering Materials Science and Engineering (MSE) Basic Knowledge of Materials Resultant Knowledge of Structure and Properties Applied of Materials Materials Science Materials Science and Engineering Materials Engineering Materials knowledge spectrum. Using the combined knowledge of materials from materials science and materials engineering enables engineers to convert materials into the products needed by society. The search for new materials and invention of products go on continuously !!!

Materials Science and Engineering (MSE) Processing- how materials are shaped into useful components to cause changes in the properties of different materials. Structure- relates to the arrangement of atoms. Properties- relates to the materials’ shape and size. Performance- be the function of its properties. Processing Structure Properties Performance The four components of the discipline of materials science and engineering and their linear interrelationship.

Classification of Materials Can be divided into three main or fundamental classes: Metallic materials. Polymeric materials. Ceramic materials. Besides the three main classes of materials, we shall consider two processing or applicational classes: Composites materials. Semiconductors

Metallic Materials Usually combinations of metallic elements. May also contain some nonmetallic elements (carbon, nitrogen, oxygen) Good thermal and electrical conductors, not transparent to visible light, strong and ductile at room temperature, maintain good strength even at high temperature. Examples: iron, copper, aluminum, nickel.

Polymeric Materials Include the familiar plastic and rubber materials. Organic compounds that are chemically based on carbon, hydrogen, and other non-metallic elements. Typically have low densities, extremely flexible, poor conductors of electricity, good insulators, not suitable for high temperature applications, resistance to corrosive chemicals. Examples: polyethylene, epoxy, natural rubber.

Ceramic Materials Compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. Composed of clay minerals, cement, and glass. High strength and hardness, hard but very brittle, wear resistance, insulative to the passage of electricity and heat. Examples: silicon oxide, alumina, silicon carbide.

Composites Materials Two or more materials (phase or constituents) integrated to form a new one. Consist of a selected filler or reinforcing material and a compatible resin binder to obtain the specific characteristics and properties desired. Can be classified into metal matrix composite (MMC), ceramic matrix composite (CMC) and polymer matrix composites (PMC). Examples: concrete, plywood, fiberglass Fiberglass is made by dispersing glass fibers in a polymer matrix.

Semiconductors Have electrical properties that are intermediate between the electrical conductors and insulators. Silicon, germanium, and gallium arsenide-based semiconductors such as those used in computers and electronics are part of a broader class of materials known as electronic materials. The electrical characteristics are extremely sensitive to the presence of minute concentrations of impurity atoms.

Why do we need to study materials science and engineering? Question Why do we need to study materials science and engineering?

Why the Study of Materials is Important Production and processing of materials constitute a large part of our economy. Engineers choose materials to suite design. New materials might be needed for some new applications. Example :- High temperature resistant materials. Space station and Mars Rovers should sustain conditions in space. * High speed, low temperature, strong but light. Modification of properties might be needed for some application. Example :- Heat treatment to modify properties. Materials science deals with basic knowledge about the internal structure, properties and processing of materials. Materials engineering deals with the application of knowledge gained by materials science to convert materials to products.