Six Materials That Changed Your World PDF

## Six Materials That Changed Your World ### 1.3 Six Materials That Changed Your World * The most obvious question is, "What materials are available to me?" * Six categories are distinguished: * Metals * Ceramics * Glasses * Polymers * Composites * Semiconductors ### Stee...

## Six Materials That Changed Your World ### 1.3 Six Materials That Changed Your World * The most obvious question is, "What materials are available to me?" * Six categories are distinguished: * Metals * Ceramics * Glasses * Polymers * Composites * Semiconductors ### Steel Bridges - Introducing Metals * **Characteristics of a metal:** * Strong and can be readily formed into practical shapes. * Extensive, permanent deformability, or ductility. * Freshly cut surface has a metallic luster. * Good conductor of electrical current. * Examples: * Golden Gate Bridge connecting San Francisco with Marin County. * Opened May 27, 1937. * 2,737 meters. * Sundial Bridge in Redding, California, a 66-meter pedestrian walkway. ### Lucalox Lamps - Introducing Ceramics * Aluminum Oxide (Al₂O₃) is a ceramic. * Advantages over metallic aluminum: * Chemically stable in a wide variety of severe environments. * Significantly higher melting point (2020°C) than does metallic aluminum (660°C). * Disadvantage: * Brittleness ### Optical Fibers - Introducing Glasses * Distinction between crystalline and noncrystalline solids: * Crystalline solids have atoms stacked in a regular, repeating pattern. * Noncrystalline solids have atoms stacked in an irregular, random pattern. * "Glass" refers to noncrystalline solids. * Example: * Ordinary window glass is approximately 72% silica (SiO₂) by weight with the balance being sodium oxide (Na₂O) and calcium oxide (CaO). ### Nylon Parachutes - Introducing Polymers * Polymers: * Are human-made, organic materials. * Long-chain molecules comprised of many single hydrocarbon molecules (mers). * Example: * Nylon (polyhexamethylene adipamide): * Invented in 1935. * Initially used as bristles in toothbrushes. * As a replacement for silk stockings. * During WWII for parachutes and other military supplies. ### Kevlar® Reinforced Tires - Introducing Composites * A composite comprises materials from different categories for combining the best properties of each material. * Example: * Fiberglass: small-diameter glass fibers embedded in a polymer matrix. * Kevlar: * A DuPont trade name for polymer reinforcements. * Provides significant advances over traditional glass fibers. * Used in high-performance tires, pressure vessels, and other demanding applications. ### Silicon Chips - Introducing Semiconductors * Semiconductors: * Exhibit an intermediate conductivity. * Neither a good electrical conductor nor a good electrical insulator. * Used in solid-state electronics. * Example: * Silicon (Si) and germanium (Ge) are used in microcircuitry. ### Figure Descriptions * **Figure 1.2:** The Golden Gate Bridge north of San Francisco, California. * **Figure 1.3:** The Sundial Bridge in Redding, California. * **Figure 1.4:** Periodic table with the elements associated with commercial polymers. * **Figure 1.5:** A technician observes the production of chemically stable oxide ceramics. * **Figure 1.6:** High-temperature sodium vapor street lamps that use a translucent Al₂O₃ cylinder as a vessel for the sodium vapor. * **Figure 1.7:** Periodic table showing the elements that form ceramic compounds. * **Figure 1.8:** Schematic comparison of the atomic-scale structure of (a) a ceramic (crystalline) and (b) a glass (noncrystalline). * **Figure 1.9:** Common silicate glasses for engineering applications. * **Figure 1.10:** A small cable containing 144 glass fibers next to a traditional copper wire cable. * **Figure 1.11:** Miscellaneous internal parts of a parking meter are made of an acetal polymer. * **Figure 1.12:** Illustration of a nylon parachute. * **Figure 1.13:** Periodic table indicating the elements found in semiconductors. * **Figure 1.14:** Example of fiberglass composite. * **Figure 1.15:** Automobile aquaplaning at a test track with Kevlar reinforced high-performance tires. * **Figure 1.16:** An illustration of a microchip.