496Tc0101-1411/9/0517:02page6 REVISED PAGES EQA 6. Chapter 1 / Introduction Figure 1. Metals Bar-chart of roo temperature density Platinum values for various metals, ceramics. y Silver Ceramics polymers, and s composite materials. PTFE GFRC Magnesium Concrete regard to mechanical characteristics, these materials are relatively stiff(Figure 1.4) and strong(Figure 1.5), yet are ductile (i.e, capable of large amounts of deformation without fracture), and are resistant to fracture(Figure 1.6), which accounts for their widespread use in structural applications. Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms. Many properties of metals are directly attributable to these electrons. For example, metals are extremely good conductors of electricity(Figure 1.7)and heat, and are not trans- parent to visible light; a polished metal surface has a lustrous appearance. In addi- tion, some of the metals(viz., Fe, Co, and Ni) have desirable magnetic properties. Figure 1. 8 is a photograph that shows several common and familiar objects that are made of metallic materials. Furthermore, the types and applications of metals and their alloys are discussed in Chapter 11 Ceramics Ceramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, some of the common ceramic Bar-chart of room- (i. e, elastic modulus) g 0 alues for various ASiaNa Magnesium Concrete composite materials. Polymers Woods 01
6 • Chapter 1 / Introduction Density (g/cm3) (logarithmic scale) 40 20 10 8 6 4 2 1.0 0.8 0.6 0.2 0.4 0.1 Metals Platinum Silver Copper Iron/Steel Titanium Aluminum Magnesium Composites GFRC CFRC Woods Polymers PTFE PVC PS PE Rubber ZrO2 Al2O3 SiC,Si3N4 Glass Concrete Ceramics Figure 1.3 Bar-chart of roomtemperature density values for various metals, ceramics, polymers, and composite materials. Figure 1.4 Bar-chart of roomtemperature stiffness (i.e., elastic modulus) values for various metals, ceramics, polymers, and composite materials. 10 1.0 0.1 100 1000 0.01 0.001 Stiffness [Elastic (or Young’s) Modulus (in units of gigapascals)] (logarithmic scale) Composites GFRC CFRC Woods Polymers PVC PTFE PE Rubbers PS, Nylon Metals Tungsten Iron/Steel Aluminum Magnesium Titanium Ceramics SiC AI2O3 Si3N4 ZrO2 Glass Concrete regard to mechanical characteristics, these materials are relatively stiff (Figure 1.4) and strong (Figure 1.5), yet are ductile (i.e., capable of large amounts of deformation without fracture), and are resistant to fracture (Figure 1.6), which accounts for their widespread use in structural applications. Metallic materials have large numbers of nonlocalized electrons; that is, these electrons are not bound to particular atoms. Many properties of metals are directly attributable to these electrons. For example, metals are extremely good conductors of electricity (Figure 1.7) and heat, and are not transparent to visible light; a polished metal surface has a lustrous appearance. In addition, some of the metals (viz., Fe, Co, and Ni) have desirable magnetic properties. Figure 1.8 is a photograph that shows several common and familiar objects that are made of metallic materials. Furthermore, the types and applications of metals and their alloys are discussed in Chapter 11. Ceramics Ceramics are compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, and carbides. For example, some of the common ceramic 1496T_c01_01-14 11/9/05 17:02 Page 6 REVISED PAGES
496Tc0101-1412/20/057:11page7 2nd REVISE PaGeS EQA 1.4 Classification of materials 7 Figure Bar-chart of r Metals Composites temperatu rength (i.e, tensile strength) o Ceramics ≌a1000 Steel alloys CFRC metals, ceramics, =9 polymers, and alloys composite materials. Aluminum 016 Polymers Woods PTFE materials include aluminum oxide(or alumina, Al2O3), silicon dioxide(or silica, SiOz) silicon carbide (SiC), silicon nitride(Si,N4), and, in addition, what some refer to as the traditional ceramics-those composed of clay minerals (i.e, porcelain), as well as cement, and glass. With regard to mechanical behavior, ceramic materials are rela tively stiff and strong--stiffnesses and strengths are comparable to those of the met- als(Figures 1.4 and 1.5). In addition, ceramics are typically very hard. On the other hand, they are extremely brittle (lack ductility), and are highly susceptible to fracture (Figure 1.6). These materials are typically insulative to the passage of heat and elec- tricity (i.e, have low electrical conductivities, Figure 1.7), and are more resistant to gh temperatures and harsh environments than metals and polymers. With regard to ptical characteristics, ceramics may be transparent, translucent, or opaque(Figure 1.2), and some of the oxide ceramics(e. g, Fe3O4) exhibit magnetic behavior Metals alloys Ceramics Wood Concrete Figure 1.6 Bar-chart of room-temperature resistance to fracture (ie, fracture toughnes for various metals, ceramics, polymers, and composite materials.(Reprinted from Engineering Materials 1: An Introduction to Properties, Applications and Design, third edition, M. F. Ashby and D.R. H. Jones, pages 177 and 178, Copyright 2005, with permission from Elsevier)
materials include aluminum oxide (or alumina,Al2O3), silicon dioxide (or silica, SiO2), silicon carbide (SiC), silicon nitride (Si3N4), and, in addition, what some refer to as the traditional ceramics—those composed of clay minerals (i.e., porcelain), as well as cement, and glass. With regard to mechanical behavior, ceramic materials are relatively stiff and strong—stiffnesses and strengths are comparable to those of the metals (Figures 1.4 and 1.5). In addition, ceramics are typically very hard. On the other hand, they are extremely brittle (lack ductility), and are highly susceptible to fracture (Figure 1.6). These materials are typically insulative to the passage of heat and electricity (i.e., have low electrical conductivities, Figure 1.7), and are more resistant to high temperatures and harsh environments than metals and polymers. With regard to optical characteristics, ceramics may be transparent, translucent, or opaque (Figure 1.2), and some of the oxide ceramics (e.g., Fe3O4) exhibit magnetic behavior. 1.4 Classification of Materials • 7 Strength (Tensile Strength, in units of megapascals) (logarithmic scale)1000 100 10 Nylon PS PE PVC PTFE Polymers Steel alloys Gold Aluminum alloys Cu,Ti alloys Metals CFRC GFRC Composites Woods Glass Si3N4 SiC Ceramics Al2O3 Figure 1.5 Bar-chart of roomtemperature strength (i.e., tensile strength) values for various metals, ceramics, polymers, and composite materials. Figure 1.6 Bar-chart of room-temperature resistance to fracture (i.e., fracture toughness) for various metals, ceramics, polymers, and composite materials. (Reprinted from Engineering Materials 1: An Introduction to Properties, Applications and Design, third edition, M. F. Ashby and D. R. H. Jones, pages 177 and 178, Copyright 2005, with permission from Elsevier.) Resistance to Fracture (Fracture Toughness, in units of MPa m) (logarithmic scale) 100 10 1.0 0.1 Composites CFRC GFRC Wood Nylon Polymers Polystyrene Polyethylene Polyester Al2O3 SiC Si3N4 Glass Concrete Ceramics Metals Steel alloys Titanium alloys Aluminum alloys 1496T_c01_01-14 12/20/05 7:11 Page 7 2nd REVISE PAGES
496Tc0101-1412/20/057:11page8 2nd REVISE Pages EQA Bar-chart of Semiconductors for metals, ceramics 0 conductivity ranges polymers, materials. Ceramics Polymers s Several common ceramic objects are shown in the photograph of Figure 1.9 The characteristics, types, and applications of this class of materials are discussed in Chapters 12 and 13 Polymers Polymers include the familiar plastic and rubber materials. Many of them are organic ompounds that are chemically based on carbon, hydrogen, and other nonmetallic elements(viz. O, N, and Si). Furthermore, they have very large molecular structures, often chain-like in nature that have a backbone of carbon atoms some of the com- mon and familiar polymers are polyethylene(PE), nylon, poly ( vinyl chloride) (PVC), polycarbonate(PC), polystyrene(PS), and silicone rubber. These materials typically have low densities(Figure 1.3), whereas their mechanical characteristics are generally dissimilar to the metallic and ceramic materials--they are not as stiff nor as strong as these other material types(Figures 1.4 and 1.5). However, on the basis of their low densities, many times their stiffnesses and strengths on a per mass Figure 1.8 Familiar made of metals and metal alloys:(from silverware(fork and knife) S coIns ring, and a nut and bolt (Photograpy by
Several common ceramic objects are shown in the photograph of Figure 1.9. The characteristics, types, and applications of this class of materials are discussed in Chapters 12 and 13. Polymers Polymers include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (viz. O, N, and Si). Furthermore, they have very large molecular structures, often chain-like in nature that have a backbone of carbon atoms. Some of the common and familiar polymers are polyethylene (PE), nylon, poly(vinyl chloride) (PVC), polycarbonate (PC), polystyrene (PS), and silicone rubber. These materials typically have low densities (Figure 1.3), whereas their mechanical characteristics are generally dissimilar to the metallic and ceramic materials—they are not as stiff nor as strong as these other material types (Figures 1.4 and 1.5). However, on the basis of their low densities, many times their stiffnesses and strengths on a per mass 8 • Chapter 1 / Introduction Figure 1.8 Familiar objects that are made of metals and metal alloys: (from left to right) silverware (fork and knife), scissors, coins, a gear, a wedding ring, and a nut and bolt. (Photograpy by S. Tanner.) Figure 1.7 Bar-chart of roomtemperature electrical conductivity ranges for metals, ceramics, polymers, and semiconducting materials. Electrical Conductivity (in units of reciprocal ohm-meters) (logarithmic scale) 108 104 1 10–12 10–8 10–4 10–16 10–20 Ceramics Polymers Semiconductors Metals 1496T_c01_01-14 12/20/05 7:11 Page 8 2nd REVISE PAGES
496Tc0101-1412/20/057:11page9 2nd REVISE PaGeS EQA 1.4 Classification of materials 9 Figure 1.9 Common objects that are made of eramic materials: scissors, a china tea cup, a building brick, a floor tile. and a S. Tanner) basis are comparable to the metals and ceramics. In addition, many of the polymers are extremely ductile and pliable (i.e, plastic), which means they are easily formed into complex shapes. In general, they are relatively inert chemically and unreactive in a large number of environments. One major drawback to the polymers is their tendency to soften and/or decompose at modest temperatures, which, in some in- stances, limits their use. Furthermore, they have low electrical conductivities(Fig- ure 1.7) and are nonmagnetic The photograph in Figure 1.10 shows several articles made of polymers that are familiar to the reader. Chapters 14 and 15 are devoted to discussions of the struc- tures, properties, applications, and processing of polymeric materials. Figure 1.10 Several common objects that are made of polymeric materials plastic tableware (spoon, fork, and knife), billiard balls. a bicycle helmet, two a plastic milk carton. (Photog by S Tanner.)
basis are comparable to the metals and ceramics. In addition, many of the polymers are extremely ductile and pliable (i.e., plastic), which means they are easily formed into complex shapes. In general, they are relatively inert chemically and unreactive in a large number of environments. One major drawback to the polymers is their tendency to soften and/or decompose at modest temperatures, which, in some instances, limits their use. Furthermore, they have low electrical conductivities (Figure 1.7) and are nonmagnetic. The photograph in Figure 1.10 shows several articles made of polymers that are familiar to the reader. Chapters 14 and 15 are devoted to discussions of the structures, properties, applications, and processing of polymeric materials. 1.4 Classification of Materials • 9 Figure 1.9 Common objects that are made of ceramic materials: scissors, a china tea cup, a building brick, a floor tile, and a glass vase. (Photography by S. Tanner.) Figure 1.10 Several common objects that are made of polymeric materials: plastic tableware (spoon, fork, and knife), billiard balls, a bicycle helmet, two dice, a lawnmower wheel (plastic hub and rubber tire), and a plastic milk carton. (Photography by S. Tanner.) 1496T_c01_01-14 12/20/05 7:11 Page 9 2nd REVISE PAGES
496Tc0101-1411/9/0517:02Page1 REVISED PAGES EQA 10.Chapter 1 Introduction MATERIALS OF IMPORTANCE Carbonated Beverage Containers ne common item that presents some inter- and unreactive with beverages. In addition, each esting material property requirements is the material has its pros and cons. For example, the container for carbonated beverages. The material aluminum alloy is relatively strong(but easily used for this application must satisfy the follow. dented), is a very good barrier to the diffusion of ing constraints:(1)provide a barrier to the pas-I carbon dioxide, is easily recycled, beverages are sage of carbon dioxide, which is under pressure in cooled rapidly, and labels may be painted onto its the container; (2)be nontoxic, unreactive with the surface On the other hand, the cans are opticall beverage,and,preferably be recyclable; (3)be rel- opaque, and relatively expensive to produce Glass atively strong, and capable of surviving a drop is impervious to the passage of carbon dioxide, is from a height of several feet when containing the a relatively inexpensive material, may be recycled, beverage;(4)be inexpensive and the cost to fab- but it cracks and fractures easily, and glass bottles ricate the final shape should be relatively low; are relatively heavy. Whereas the plastic is rela (5)if optically transparent, retain its optical clar- tively strong, may be made optically transparent, ity;and(6) capable of being produced having is inexpensive and lightweight, and is recyclable, it different colors and/or able to be adorned with is not as impervious to the passage of carbon diox decorative labels ide as the aluminum and glass. For example, you All three of the basic material types-metal may have noticed that beverages in aluminum and amic(glass), and polymer(poly- glass containers retain their carbonization(i.e ester plastic)-are used for carbonated beverage"fizz")for several years, whereas those in two-liter containers(per the chapter-opening photographs plastic bottles "go flat"within a few months. for this chapter ). All of these materials are nontoxic Composites A composite is composed of two(or more) individual materials, which come from the categories discussed above-viz, metals, ceramics, and polymers. The design goal of a composite is to achieve a combination of properties that is not displayed by any single material, and also to incorporate the best characteristics of each of the component materials. A large number of composite types exist that are represented by different combinations of metals, ceramics, and polymers. Furthermore, some naturally-occurring materials are also considered to be composites--for example, wood and bone. However, most of those we consider in our discussions are syn- thetic(or man-made) composites. One of the most common and familiar composites is fiberglass, in which small glass fibers are embedded within a polymeric material (normally an epoxy or polyester). The glass fibers are relatively strong and stiff (but also brittle), whereas he polymer is ductile(but also weak and flexible). Thus, the resulting fiberglass is relatively stiff, strong,(Figures 1.4 and 1.5) flexible, and ductile. In addition, it has a low density(Figure 1.3) Another of these technologically important materials is the"carbon fiber reinforced polymer"(or"CFRP")composite--carbon fibers that are embedded within a polymer. These materials are stiffer and stronger than the glass fiber-reinforced materials(Figures 1.4 and 1.5), yet they are more expensive. The CFRP composites Fiberglass is sometimes also termed a"glass fiber-reinforced polymer"composite, abbrevi- ated“GFRP
10 • Chapter 1 / Introduction Carbonated Beverage Containers MATERIALS OF IMPORTANCE One common item that presents some interesting material property requirements is the container for carbonated beverages. The material used for this application must satisfy the following constraints: (1) provide a barrier to the passage of carbon dioxide, which is under pressure in the container; (2) be nontoxic, unreactive with the beverage, and, preferably be recyclable; (3) be relatively strong, and capable of surviving a drop from a height of several feet when containing the beverage; (4) be inexpensive and the cost to fabricate the final shape should be relatively low; (5) if optically transparent, retain its optical clarity; and (6) capable of being produced having different colors and/or able to be adorned with decorative labels. All three of the basic material types—metal (aluminum), ceramic (glass), and polymer (polyester plastic)—are used for carbonated beverage containers (per the chapter-opening photographs for this chapter).All of these materials are nontoxic and unreactive with beverages. In addition, each material has its pros and cons. For example, the aluminum alloy is relatively strong (but easily dented), is a very good barrier to the diffusion of carbon dioxide, is easily recycled, beverages are cooled rapidly, and labels may be painted onto its surface. On the other hand, the cans are optically opaque, and relatively expensive to produce. Glass is impervious to the passage of carbon dioxide, is a relatively inexpensive material, may be recycled, but it cracks and fractures easily, and glass bottles are relatively heavy. Whereas the plastic is relatively strong, may be made optically transparent, is inexpensive and lightweight, and is recyclable, it is not as impervious to the passage of carbon dioxide as the aluminum and glass. For example, you may have noticed that beverages in aluminum and glass containers retain their carbonization (i.e., “fizz”) for several years, whereas those in two-liter plastic bottles “go flat” within a few months. 4 Fiberglass is sometimes also termed a “glass fiber-reinforced polymer” composite, abbreviated “GFRP.” Composites A composite is composed of two (or more) individual materials, which come from the categories discussed above—viz., metals, ceramics, and polymers.The design goal of a composite is to achieve a combination of properties that is not displayed by any single material, and also to incorporate the best characteristics of each of the component materials. A large number of composite types exist that are represented by different combinations of metals, ceramics, and polymers. Furthermore, some naturally-occurring materials are also considered to be composites—for example, wood and bone. However, most of those we consider in our discussions are synthetic (or man-made) composites. One of the most common and familiar composites is fiberglass, in which small glass fibers are embedded within a polymeric material (normally an epoxy or polyester).4 The glass fibers are relatively strong and stiff (but also brittle), whereas the polymer is ductile (but also weak and flexible). Thus, the resulting fiberglass is relatively stiff, strong, (Figures 1.4 and 1.5) flexible, and ductile. In addition, it has a low density (Figure 1.3). Another of these technologically important materials is the “carbon fiberreinforced polymer” (or “CFRP”) composite—carbon fibers that are embedded within a polymer. These materials are stiffer and stronger than the glass fiber-reinforced materials (Figures 1.4 and 1.5), yet they are more expensive. The CFRP composites 1496T_c01_01-14 11/9/05 17:02 Page 10 REVISED PAGES