Lecture 1 6pp - 1 Why Materials Science? B747, taking...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Why Materials Science? B747, taking < 15 hrs to travel from Chicago to Hong Kong Max takeoff weight = 875,000 lbs (empty weight = 358,000 lbs) Aluminum alloys weigh 150,000 lbs 1 2 Why Materials Science? In 1990, storage density = 0.1 Gb/in 2 ; cost = $1/MB In 2006, storage density ~ 100 Gb/in 2 ; cost = $2/GB In 2007, storage density > 130 Gb/in 2 ; cost < $1/GB 2 3 Why Materials Science? Over 500,000 implant operations per year About half are revisions Each step produces 50 to 100K wear particles 3 4 Why Materials Science? We have trillions of dollars worth of infrastructure (highway and bridges) in the US. How does one choose the type of steel used in each case? 4 5 MSE Paradigm Properties Structure/ Composition Performance Processing/ Synthesis 5 Fiber Optic Communications Fiber-optic systems have multiple materials Semiconductor lasers emitting at desired wavelength Glass bers with very low losses Fiber ampliers Optical lters Semiconductor detectors 6 6 7 Fundamental Principle 1 Properties of a material depend on its structure graphite diamond carbon nanotube C60 buckyball 7 8 8 9 Fundamental Principle 2 A material acquires a certain equilibrium structure in order to attain the lowest total free energy for the system 2s 2p x 2p y 2p z Carbon atom sp 3 hybridization 2s 2p x 2p y 2p z Diamond 9 10 Fundamental Principle 3 Properties depend directly on synthesis or processing techniques carbon ion energy (eV) carbon sp 3 fraction ~ 100 eV ~ 90% 10 11 Atom/Molecular Bonding Ionic Covalent Metallic Dipole 11 12 Ionic Bonding U = " A R + B R n Na + Cl- A = e 2 /4 !" o , e electron charge, " o permittivity of free space, B and n ( # 5-12) are empirical constants 12 13 Distance Potential energy Binding/cohesive energy Equilibrium separation 13 14 Table of Ionic Radii Ion Radius (nm) Li + 0.060 Na + 0.095 K + 0.133 Rb + 0.148 Cs + 0.169 F 0.136 Cl 0.181 Br 0.195 I 0.216 14 15 Ionic Bonding Larger ions % larger separation % weaker binding Compound Cohesive energy (kJ/mole)...
View Full Document

This note was uploaded on 11/21/2011 for the course MAT SCI 201 taught by Professor Matsci during the Spring '10 term at Northwestern.

Page1 / 9

Lecture 1 6pp - 1 Why Materials Science? B747, taking...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online