Lecture 2 - ENGR 4250U Advanced Materials Engineering...

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ENGR 4250U– Advanced Materials Engineering Lecture2 Introduction - 2 1 Dr. A. Keshavarz - ENGR 4250U
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Materials Classification Metals Polymers Ceramics Metal-polymer composites Metals-ceramic composites Ceramic-polymer composites 2 Dr. A. Keshavarz - ENGR 4250U
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Types of Materials Metals : Strong, ductile opaque, reflective. Polymers/plastics : Covalent bonding sharing of e s Soft, ductile, low strength, low density Optically translucent or transparent. Ceramics : ionic bonding (refractory) compounds of metallic Brittle, glassy, elastic non-conducting (insulators) 3 Dr. A. Keshavarz - ENGR 4250U
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ex: hardness vs structure of steel Properties depend on structure Data obtained from Figs. 10.30(a) and 10.32 with 4 wt% C composition, and from Fig. 11.14 and associated discussion, Callister 7e . Micrographs adapted from (a) Fig. 10.19; (b) Fig. 9.30;(c) Fig. 10.33; and (d) Fig. 10.21, Callister 7e . ex: structure vs cooling rate of steel Processing can change structure Hardness (BHN) Cooling Rate (ºC/s) 100 200 300 400 500 600 0.01 0.1 1 10 100 1000 (d) 30 µ m (c) 4 µ m (b) 30 µ m (a) 30 µ m 4 Dr. A. Keshavarz - ENGR 4250U
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1. Pick Application Determine required Properties 2. Properties Identify candidate Material(s) 3. Material Identify required Processing Processing: changes structure and overall shape ex: casting, sintering, vapor deposition, doping forming, joining, annealing. Properties: mechanical, electrical, thermal, magnetic, optical, deteriorative. Material: structure, composition. The Materials Selection Process 5 Dr. A. Keshavarz - ENGR 4250U
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Use the right material for the job. Understand the relation between properties , structure , and processing . Recognize new design opportunities offered by materials selection. Course Goals 6 Dr. A. Keshavarz - ENGR 4250U
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Atomic Bonds • Ionic • Metallic • Covalent • Secondary 7 Dr. A. Keshavarz - ENGR 4250U
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Ionic and Covalent Nature % ionic character = {1-exp[ - (0.25)(X A – X B ) 2 ]} x 100 (2.10) X A and X B are electro-negativities for the respective elements 8 Dr. A. Keshavarz - ENGR 4250U
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Crystal Systems 9 Dr. A. Keshavarz - ENGR 4250U
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Unit Cells Small repeat entity Chosen to represent symmetry of crystal structure Building block Usually corners coincide with atom centers 10 Dr. A. Keshavarz - ENGR 4250U
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Non dense, random packing Dense, regular packing Dense, regular -packed structures tend to have lower energy. ENERGY AND PACKING F r 11 Dr. A. Keshavarz - ENGR 4250U
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tend to be densely packed. have the simplest crystal structures.
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This note was uploaded on 06/02/2011 for the course ECONMICS ECN204 taught by Professor Brenan during the Spring '08 term at Ryerson.

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Lecture 2 - ENGR 4250U Advanced Materials Engineering...

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