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So, what is stuff made of ?

This section delves into various categories of materials like Organics, Metals, Polymers, Ceramics, and Composites. Organics, Metals, Alloys, Polymers, Ceramics, and Composites have unique properties and uses in various applications. Metals, such as aluminum, copper, and gold, possess high strength and conductivity. Polymers, like plastics, are chain-like molecules that can be molded, while ceramics have high melting points due to their crystalline structure. Composites combine different materials to enhance specific properties. Materials like cotton, wood, metals, and polymers are used in everyday products. The section also includes answers to related case studies and questions.

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So, what is stuff made of ?

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  1. So, what is stuff made of ? Section 4.6

  2. Categories of Materials Organics Metals and Alloys Polymers Ceramics Composites

  3. Organics • Organics are or were living organisms • Composed of mostly Carbon and Hydrogen • Structure depends on the way cells developed not by human manipulation • Renewable, sustainable • Infinite variety • Genetically alterable

  4. Metals and Alloys • Metals are pure elements which comprise about three-fourths of the periodic table • Few are used in their pure form because of: • Hardness; too hard or too soft • Cost; scarcity of element • Engineers need certain characteristics that can only be accomplished by a blending of basic elements • Metallic materials include alloys, which are combinations of metals and other elements

  5. Metals • Possess material properties, including: • high strength and toughness • high electrical conductance • high thermal conductance • luster • Examples • aluminum - copper - gold - zinc - iron - lead - nickel • silver - thorium - chromium - tin - beryllium

  6. Alloys • Consist of materials composed of two or more elements, at least one being a metal • This combination of elements gives the material a combination of properties from each element • Examples • Steel- iron, carbon and impurity elements such as boron copper or silicon • Brass - copper, zinc • Stainless Steel - nickel,iron • Monel - nickel,copper

  7. Polymers • Polymers • Chain-like molecule made of many (poly) smaller molecular units (mono”mers”) • Chaining (polymerization) is responsible for the formation of natural fibers, wood, rubber, skin, bone and the tissues of animals, humans and insects Polymers- use mostly H, C, N, O, F, SI, S and Cl.

  8. Plastics • Plastics • Human-made polymers • Plastics are workable or moldable • Thermosetting plastics are formable once (e.g. epoxy, phonelic (Bakelite), polyurethane) • Thermoplastics can be heated repeatedly and formed into new shapes (e.g. polyethylene, nylon, Plexiglas)

  9. Ceramics • Crystalline compounds combining metallic and non metallic elements • Mostly use silicon, carbon and oxygen. • The absence of free electrons make ceramics poor electrical conductors. • Because of the strength of the bonding, ceramics have high melting temperatures

  10. Composites • Laminar or Layer Composites - alternate layers of materials bonded together. (e.g. plywood, safety glass, Formica, bimetallic strips) • Particulate Composites - discrete particles of one material surrounded by a matrix of another material. (e.g. concrete, asphalt, powdered metals and ceramics) • Fiber-Reinforced Composites - composed of continuous or discontinuous fibers embedded in a matrix of another material. (e.g. Kevlar, rayon, steel reinforced tires, fiberglass, graphite-epoxy)

  11. Answers to 4.6 Case Study • a) Perhaps cotton clothing and wood furniture. • b) Materials scientists use most of the elements in the periodic table. • c) Perhaps products such as toys, clothing and automobiles. • d) Metals used in 5000 B.C. would have included gold, silver and copper. • e) Metals such as iron, aluminum nickel, titanium, and tungsten were in use.

  12. f) Metals can be mixed in different combinations to yield alloys with specific properties such as hardness, flexibility, or resistance to corrosion. • g) Natural elastomers could include vines as a substitute for rope. • h) Indestructible polymers can be a waste-disposal problem. • i) Plastics are recycled. • j) Carbon fibre is used in sporting equipment such as tennis racquets.

  13. k) Paper contains plant fibres and wood pulp. • l) Metal canoes are durable and inexpensive but heavy and noisy. Kevlar canoes are light but fragile and expensive. Wood canoes are attractive but heavy. Plastic (ABS) canoes are very tough but heavy. • m) ABS canoes are ideal for rapids, Kevlar for tripping involving portages, and wood canoes fro lade tripping. Fibreglass canoes are a good compromise.

  14. Question 2 on page 119 • 2. a) Polymers could include nylon, polyester, rubber, wool, and leather. • b) Ceramics could include pottery, stoneware, enamels, and carbon fibre. • c) Metals could include iron, aluminum, copper, gold and nickel. • d) Composites could include fiberglass, paper, and reinforced concrete.

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