84. Mixed-metal oxides (SrTiO3, MgAl2O4, YBa2Cu3O7-x, having vacancy defects.)
85. Nitrides (Si3N4, AlN, GaN, BN, and TiN, which are used for hard coatings.)</li></ul>13<br />
86. Classes and Properties: Polymers<br />Distinguishing features <br /><ul><li> Composed primarily of C and H (hydrocarbons)
87. Low melting temperature.
88. Some are crystals, many are not.
89. Most are poor conductors of electricity and heat.
90. Many have high plasticity.
91. A few have good elasticity.
92. Some are transparent, some are opaque
93. Polymers are attractive because they are usually lightweight and inexpensive to make, and usually very easy to process, either in molds, as sheets, or as coatings.
94. Most are very resistant to the environment.
95. They are poor conductors of heat and electricity, and tend to be easy to bend, which makes them very useful as insulation for electrical wires. They are also</li></ul>14<br />
96. Classes and Properties: Polymers<br />Two main types of polymers are thermosets and thermoplastics.<br /><ul><li>Thermosets are cross-linked polymers that form 3-D networks, hence are strong and rigid.
97. Thermoplastics are long-chain polymers that slide easily past one another when heated, hence, they tend to be easy to form, bend, and break. </li></ul>15<br />
98. Classes and Properties: Polymers<br />Elements that compose polymers: limited<br />16<br />
99. Classes and Properties: Polymers<br />Applications and Examples<br /><ul><li> Adhesives and glues
131. Examples: Si, Ge, GaAs, and InSb</li></ul>20<br />
132. Classes and Properties: Composites<br />Distinguishing features<br /><ul><li> Composed of two or more different materials (e.g., metal/ceramic, polymer/polymer, etc.)
133. Properties depend on amount and distribution of each type of material.
134. Collective properties more desirable than possible with any individual material.</li></ul>Applications and Examples<br /><ul><li> Sports equipment (golf club shafts, tennis rackets, bicycle frames)
135. Aerospace materials
136. Thermal insulation
138. "Smart" materials (sensing and responding)
139. Brake materials</li></ul>Examples<br /><ul><li> Fiberglass (glass fibers in a polymer)
140. Space shuttle heat shields (interwoven ceramic fibers)
141. Paints (ceramic particles in latex)
142. Tank armor (ceramic particles in metal)</li></ul>21<br />
143. Materials Science<br /> From the polymers in the chair you’re sitting on, the metal ball-point pen you’re using, and the concrete that made the building you live or work in to the materials that make up streets and highways and the car you drive, plane you using. All these items are products of materials science and technology. Briefly defined, materials science is the study of “stuff.” Materials science is the study of solid matter.<br />
144. BREAK<br />
145. Material Science<br />The discipline of investigating the relationships that exist between the structures and properties of materials and its performance.<br />
146. What is Materials Science and Engineering ?<br />Processing -> Structure -> Properties -> Performance<br />
163. Materials Science and Engineering Core, including the end-user<br />Source: Materials science and engineering—forging stronger links to users, NRC 1999<br />
164. <ul><li>It all about the raw materials and how they are processed
165. That is why we call it materials ENGINEERING
166. Minor differencesin Raw materials or processing parameters can meanmajor changes in the performanceof the final material or product</li></li></ul><li>(d)<br />30mm<br />(c)<br />(b)<br />(a)<br />4mm<br />30mm<br />30mm<br />Properties depend on Structure (strength or hardness)<br />6<br />00<br />5<br />00<br />4<br />00<br />Hardness (BHN)<br />3<br />00<br />2<br />00<br />100<br />0.01<br />0.1<br />1<br />10<br />100<br />1000<br />Cooling Rate (ºC/s)<br />And:<br />Processing can change structure! (see above structure vs Cooling Rate)<br />
167. Another Example: Rolling of Steel<br /><ul><li>At h1, L1
168. low UTS
169. low YS
170. high ductility
171. round grains
172. At h2, L2
173. high UTS
174. high YS
175. low ductility
176. elongated grains</li></ul>Structure determines Properties but Processing determines Structure!<br />
177. Multiple Length Scales Critical in Engineering<br />In Askeland and Phule’s book, from J. Allison and W. Donlon (Ford Motor Company)<br />31<br />
178. Properties of Materials<br /><ul><li> An alternative to major classes, you may divide materials into classification according to properties.
179. One goal of materials engineering is to select materials with suitable properties for a given application, so it’s a sensible approach.
180. Just as for classes of materials, there is some overlap among the properties, so the divisions are not always clearly defined </li></ul>Mechanical properties <br /> A. Elasticity and stiffness (recoverable stress vs. strain) <br /> B. Plasticity (non-recoverable stress vs. strain)<br /> C. Strength <br /> D. Brittleness or Toughness <br /> E. Fatigue<br />32<br />
181. Properties of Materials<br />Electrical properties <br />A. Electrical conductivity and resistivity<br />Dielectric properties <br /> A. Polarizability <br /> B. Capacitance <br /> C. Ferroelectric properties <br /> D. Piezoelectric properties <br /> E. Pyroelectric properties<br />Magnetic properties <br />A. Paramagnetic properties <br /> B. Diamagnetic properties <br /> C. Ferromagnetic properties<br />33<br />
182. Properties of Materials<br />Optical properties <br /> A. Refractive index <br /> B. Absorption, reflection, and transmission <br /> C. Birefringence (double refraction)<br />Corrosion properties<br />Deteriorative properties<br />Biological properties <br />A. Toxicity <br /> B. bio-compatibility <br />34<br />
183. 400<br />300<br />(W/m-K)<br />200<br />Thermal Conductivity <br />100<br />0<br />0<br />10<br />20<br />30<br />40<br />Composition (wt% Zinc)<br />100mm<br />THERMAL Properties<br />• Space Shuttle Tiles:<br /> --Silica fiber insulation<br /> offers low heat conduction.<br />• Thermal Conductivity<br />of Copper: --It decreases when<br /> you add zinc!<br />Adapted from<br />Fig. 19.4W, Callister 6e. (Courtesy of Lockheed Aerospace Ceramics Systems, Sunnyvale, CA)<br />(Note: "W" denotes fig. is on CD-ROM.)<br />Adapted from Fig. 19.4, Callister 7e.<br />(Fig. 19.4 is adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), American Society for Metals, 1979, p. 315.)<br />
184. Fe+3%Si<br />Fe<br />Magnetization<br />Magnetic Field<br />MAGNETIC Properties<br />• Magnetic Permeability<br /> vs. Composition:<br />--Adding 3 atomic % Si makes Fe a better recording medium!<br />• Magnetic Storage:<br />--Recording medium<br /> is magnetized by<br /> recording head.<br />Adapted from C.R. Barrett, W.D. Nix, and<br />A.S. Tetelman, The Principles of<br />Engineering Materials, Fig. 1-7(a), p. 9,<br />Electronically reproduced<br />by permission of Pearson Education, Inc.,<br />Upper Saddle River, New Jersey.<br />Fig. 20.23, Callister 7e.<br />(Fig. 20.23 is from J.U. Lemke, MRS Bulletin,<br />Vol. XV, No. 3, p. 31, 1990.)<br />
185. -8<br />“as-is”<br />10<br />“held at <br />160ºC for 1 hr <br />before testing”<br />crack speed (m/s)<br />-10<br />10<br />Alloy 7178 tested in <br />saturated aqueous NaCl <br />solution at 23ºC<br />increasing load<br />4mm<br />--material:<br />7150-T651 Al "alloy"<br /> (Zn,Cu,Mg,Zr)<br />Adapted from Fig. 11.26,<br />Callister 7e. (Fig. 11.26 provided courtesy of G.H.<br />Narayanan and A.G. Miller, Boeing Commercial<br />Airplane Company.)<br />DETERIORATIVE Properties<br />• Heat treatment: slows<br /> crack speed in salt water!<br />• Stress & Saltwater...<br /> --causes cracks! <br />Adapted from Fig. 11.20(b), R.W. Hertzberg, "Deformation and Fracture Mechanics of Engineering Materials" (4th ed.), p. 505, John Wiley and Sons, 1996. (Original source: Markus O. Speidel, Brown Boveri Co.)<br />Adapted from chapter-opening photograph, Chapter 17, Callister 7e.<br />(from Marine Corrosion, Causes, and Prevention, John Wiley and Sons, Inc., 1975.)<br />
186. Electrical: Resistivity of Copper<br /> Increase resistivity of Cu<br /><ul><li> by adding impurities
187. by mechanical deformation</li></ul>Fig. 19.8 Callister<br />Resistivity<br />10-8 Ohms-m<br />scattering of e- by microstructure<br />scattering of e- impurities <br />scattering of e- by phonons<br />T (0C)<br />38<br />
188. Biomaterials: Self-Assembled Tubules<br />Potential Nanotechnology<br /><ul><li> Self-assembled 'artificial bacterium' comprised of charged membranes and cytoskeletal protein rods.
189. These rigid-walled, nano-scale capsules have potential drug delivery applications.</li></ul>G. Wong, MatSE (UIUC)<br />Nanometers: things that span ~10–9 m<br />100 nm ~ 500 atom diameters<br />39<br />
190. Brass, Cu-Zn<br />Fig. 20.4 Callister<br />Conductivity (W/m-K)<br />Wt % Zn<br />Thermal: Conduction of Brass<br /><ul><li> low from ceramic oxide (structure and conduction properties)
191. changes due to alloying in metals (even though same structure)</li></ul>Silica (SiO2) fibres<br />in space shuttle tiles<br />Fig. 23.18 Callister<br />40<br />
192. bcc Fe Fig. 6.14 Callister<br />- 200 C<br />- 100 C<br />Stress (MPa)<br />+ 25 C<br />Strain<br />Deterioration and Failure<br />e.g., Stress, corrosive environments, embrittlement, incorrect structures from improper alloying or heat treatments, …<br />USS Esso Manhattan 3/29/43<br />Fractured at entrance to NY harbor<br />http://www.uh.edu/liberty/photos/liberty_summary.html<br />41<br />
193. Questions ??<br />
194. The COMET: first jet passenger plane - 1954<br />In 1949, the COMET aircraft was a newly designed, modern jet aircraft for passenger travel. It had bright cabins due to large, square windows at most seats. It was composed of light-weight aluminum.<br />In early 1950's, the planes began falling out of the sky.<br />These tragedies changed the way aircraft were designed and the materials that were used. <br />The square windows were a "stress concentrator" and the aluminum alloys used were not "strong"enough to withstand the stresses. <br />Until then, material selection for mechanical design was not really considered in designs.<br />43<br />
195. Concorde Jetliner - August, 2000<br />A Concorde aircraft, one of the most reliable aircraft of our time, was taking off from Paris Airport when it burst into flames and crashed killing all on board. <br />Amazingly, the pilot knowingly steered the plane toward a less populated point to avoid increased loss of life. Only three people on the ground were killed.<br />Investigations determined that a jet that took-off ahead of Concorde had a fatigue-induced loss of a metallic component of the aircraft, which was left on runway. During take-off, the Concorde struck the component and catapulted it into the wing containing filled fuel tanks. From video, the tragedy was caused from the spewing fuel catching fire from nearby engine exhaust flames and damaging flight control.<br />44<br />
196. World Trade Center Collapse<br />CNN<br />Tubularconstructed building.<br />Well designed and strong.<br />Strong but not from buckling.<br />Supports lost at crash site, and the floor supported inner and outer tubular structures.<br />Heat from burning fuel adds to loss of structural support from softening of steel (strength vs. T, stress-strain behavior).<br />Building “pancakes” due to enormous buckling loads.<br />See estimate by Tom Mackie in MIE<br />45<br />
197. Alloying and Diffusion: Advances and Failures<br /><ul><li>Alloying can lead to new or enhanced properties, e.g. Li, Zr added to Al (advanced precipitation hardened 767 aircraft skin).
198. It can also be a problem, e.g. Ga is a fast diffuser at Al grain boundaries and make Al catastrophically brittle(noplastic behaviorvs.strain).
199. Need to know T vs. c phase diagrams for what alloying does.
200. Need to know T-T-T (temp - time - transition) diagrams to know treatment.</li></ul>T vs c for Ga-In <br />Bringing an plane out of the sky!<br />When Ga (in liquid state) is alloyed <br />to Al it diffusesrapidly alonggrain boundaries(more volume) making bonds weaker and limiting plastic response.<br />liquid<br />Liquid at R.T.<br />All these are concepts we will tackle.<br />T.J. Anderson and I. Ansara, J. Phase Equilibria, 12(1), 64-72 (1991).<br />46<br />