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MATERIAL TYPES. ENG 205 CE-ME-MECE-MSE UNIT 11. BASIC CONCEPTS. With regard to the chemical composition of materials (the chemical s they contain and how those ch e micals are combined) they are categorized as: Elements Compounds Mixtures. ELEMENTS.
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MATERIAL TYPES ENG 205 CE-ME-MECE-MSE UNIT 11
BASIC CONCEPTS With regard to thechemical composition of materials (the chemicalsthey contain and how those chemicals are combined) they are categorized as: • Elements • Compounds • Mixtures
ELEMENTS Elements are pure materials in their most basic form. They cannot be broken down into different constituents (ingredients). Examples of elements widely used in engineering materials are: iron (Fe), carbon (C), aluminium(Al)
COMPOUNDS Compounds consist of two or more elements that are chemically bound – which means they are combined by a chemical reaction. Example of compounds: Water – a compound of Hydrogen (H) and Oxygen (O)
MIXTURES Mixtures consist of two or more elements or compounds which are mixed together, but which are not chemically bound. Example of mixtures: ALLOYS that is, metals which have other metals and/or non-metals mixed with them. e.g. Steel (iron-carbon alloy) can include other alloying metals. ALLOYING METALS metals which are added to alloys. e.g. Chromium (Cr), Manganese (Mn) and Tungsten (W)
Engineering materials can be divided into: Metals: is an element, compound, or alloy that is a good conductor of both electricity and heat. Non-Metals: A non-metal is an element on the periodic table that does not have the properties of a metallic element. Nonmetals are usually found in nature as gases or weak, brittlesolids. All group 17 and 18 elements are nonmetals, as well as hydrogen, carbon, nitrogen, oxygen, phosphorous, sulfur (sulphur)s, and selenium.
Metals: examples of metallic materials iron (Fe) copper (Cu).
Non-Metals: examples of non-metallic materials carbon (C) silicon (Si)
COMPOSITE MATERIALS Composite materials, often shortened to composites or called compositionmaterials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct within the finished structure.
COMPOSITE MATERIALS cont’ • A composite is any material made of at least two other materials. • There are a lot of composites around you. Concrete is a composite. It's made of cement, gravel, and sand, and often has steel rods inside to make it stronger. • Those shiny balloons you get in the hospital when you're sick are made of a composite, which consists of a polyestersheet and an aluminum foil sheet, made into a sandwich.
COMPOSITE MATERIALS cont’ Composites are usually made of two parts, a fiberand a matrix. The fibre can be glass, carbon fibre, or polyethylenee. The matrix, which is the stuff that holds the fibers, is usually athermoset like an epoxy resin. The fiber is embedded in the matrix in order to make the matrix stronger. Fiber-reinforced composites have two things going for them. They are strong and light. They're often stronger than steel, but weigh much less. This means that composites can be used to make automobiles lighter, so they use less fuel.
Comp. Qs • What is a composite material? Give an example. • Define the terms “reinforcement” and “matrix”.
Answers • Composite Material: They are such as bricks (made from mud and straw) are engineered or naturally occurring material made from two or more constituent materials with different physical and chemical properties. • Reinforcement: the structural network that reinforces the materials inside. Matrix: the material surrounding the reinforcement.
EXERCISES & OVER TO YOU