ME 383 Guo
Diamond is the hardest material known: (a) true or (b) false?
(a)
What is the most common fiber material in fiber-reinforced plastics?
E-glass.
The process of converting raw materials into functional products
Manufacturing
What do bauxite and corundum have in common?
They are both minerals of alumina.
ceramics based primarily on silica and distinguished by their noncrystalline structure
glasses
A branched molecular structure is stronger in the solid state and more viscous in the molten state than a linear structure for the same polymer: (a) true or (b) false?
(a)
Degree of polymerization is which one of the following: (a) average number of mers in the molecule chain; (b) proportion of the monomer that has been polymerized; (c) sum of the molecule weights of the mers in the molecule; or (d) none of the above?
(a)
Does any polymer ever become 100% crystalline?
No
One of the oldest metals known to mankind
copper
Diamond is the hardest material known? (a) true or (b) false
(a)
Polystyrene (without plasticizers) is amorphous, transparent, and brittle: (a) true or (b) false?
(a)
an iron-carbon alloy containing from 0.02% to 2.1% carbon
Steel
an iron-carbon alloy containing from 2.1% to about 4% or 5% carbon
Cast iron
An inorganic compound consisting of a metal (or semi-metal) and one or more nonmetals
Ceramic
Which one of the following materials is closest to diamond in hardness? (a) aluminum oxide, (b) carbon dioxide, (c) cubic boron nitride, (d) silicon dioxide, or (e) tungsten carbide
(c)
Which one of the following polymer types are most commonly used in polymer matrix composites: (a) elastomers, (b) thermoplastics, or (c) thermosets?
(c)
Which one of the three polymer types is not normally considered to be a plastic: (a) thermoplastics, (b) thermosets, or (c) elastomers?
(c)
an inorganic, nonmetallic material that cools to a rigid solid without crystallization.
Glass
What is glazing, as applied to ceramics?
Glazing involves the application of a surface coating of oxides such as alumina and silica, usually to a porous ceramic product such as earthenware, to make the product more impervious to moisture and more attractive.
refers to the use of outside contractors to perform work that was traditionally accomplished inhouse
outsourcing
List some applications of high carbon steels (>0.50% C)
springs, cutting tools and blades; wear-resistant parts
A copolymer is a mixture of the macromolecules of two different homopolymers: (a) true or (b) false?
(b)
The nylons are members of which polymer group?
Polyamides
What are the three basic categories of polymers?
The categories are (1) thermoplastics, (2) thermosetting polymers, and (3) elastomers.
What is the chemical formula of ethylene, the monomer for polyethylene?
The chemical formula of ethylene is C2H4.
The 3 basic categories of ceramics
Traditional, New ceramics, and glasses
What are the general mechanical properties of ceramic materials?
Typical mechanical properties include high hardness, brittleness, and no ductility
any homogeneous mass of material, such as a metal in which the grains all have the same crystal lattice structure
a phase
List some applications of low carbon steels (< 0.20% C)
automobile sheetmetal parts, plate steel for fabrication, railroad rails
Stainless steels' principal alloying element is ___________, usually greater than 15% (to protect surface from corrosion)
chromium (or sometimes Nickel)
List some applications of medium carbon steels (0.20% ~ 0.50% C)
machinery components and engine parts such as crankshafts and connecting rods
more recently developed ceramics based on oxides, carbides, etc., with better mechanical or physical properties than traditional ceramics
new ceramics
In addition to corrosion resistance, stainless steels are noted for their combination of __________ and __________
strength; ductility
Of the three polymer types, which one is the most important commercially: (a) thermoplastics, (b) thermosets, or (c) elastomers?
(a)
Of the three polymer types, which one is the most important commercially? (a) thermoplastics, (b) thermosets, or (c) elastomers
(a)
Solid solution alloying is the principal strengthening mechanism in high strength low alloy (HSLA) steels? (a) true or (b) false
(a)
Solid solution alloying is the principal strengthening mechanism in high-strength low-alloy (HSLA) steels: (a) true or (b) false?
(a)
The basic difference between low-density polyethylene and high-density polyethylene is that the latter has a much higher degree of crystallinity: (a) true or (b) false?
(a)
The fiber rayon used in textiles is based on which one of the following polymers: (a) cellulose, (b) nylon, (c) polyester, (d) polyethylene, or (e) polypropylene?
(a)
The strength and hardness of steel increases as carbon content (a) increases or (b) decreases
(a)
The strength and hardness of steel increases as carbon content (a) increases or (b) decreases?
(a)
Which of the following best characterizes the structure of glass-ceramics: (a) 95% polycrystalline, (b) 95% vitreous, or (b) 50% polycrystalline?
(a)
Which of the following metals is noted for its good electrical conductivity (one best answer)? (a) copper, (b) gold, (c) iron, (d) nickel, or (e) tungsten?
(a)
Which of the following metals is noted for its good electrical conductivity (one best answer): (a) copper, (b) gold, (c) iron, (d) nickel, or (e) tungsten?
(a)
Which one of the following elements is the most important alloying ingredient in steel: (a) carbon, (b) chromium, (c) nickel, (d) molybdenum, or (e) vanadium?
(a)
Which one of the following elements is the most important alloying ingredient in steel? (a) carbon, (b) chromium, (c) nickel, (d) molybdenum, or (e) vanadium
(a)
Which one of the following reinforcing geometries offers the greatest potential for strength and stiffness improvement in the resulting composite material: (a) fibers, (b) flakes, (c) particles, or (d) infiltrated phase?
(a)
Which one of the metallic elements is the most abundant on the earth: (a) aluminum, (b) copper, (c) iron, (d) magnesium, or (e) silicon?
(a)
Which one of the metallic elements is the most abundant on the earth? (a) aluminum, (b) copper, (c) iron, (d) magnesium, or (e) silicon?
(a)
Which one of the three polymer types does not involve cross-linking: (a) thermoplastics, (b) thermosets, or (c) elastomers?
(a)
Properties and characteristics of the glass-ceramics include which of the following (two best answers): (a) efficiency in processing, (b) electrical conductor, (c) high thermal expansion, and (d) strong, relative to other glasses?
(a) and (d)
Which of the following alloying elements are most commonly associated with stainless steel (two best answers)? (a) chromium, (b) manganese, (c) molybdenum, (d) nickel, and (e) tungsten
(a) and (d)
Which of the following alloying elements are most commonly associated with stainless steel (two best answers): (a) chromium, (b) manganese, (c) molybdenum, (d) nickel, and (e) tungsten?
(a) and (d)
Which of the following ceramics are commonly used as abrasives in grinding wheels (two best answers)? (a) aluminum oxide, (b) calcium oxide, (c) carbon monoxide, (d) silicon carbide, and (e) silicon dioxide
(a) and (d)
Which of the following ceramics are commonly used as abrasives in grinding wheels (two best answers): (a) aluminum oxide, (b) calcium oxide, (c) carbon monoxide, (d) silicon carbide, and (e) silicon dioxide?
(a) and (d)
Which of the following polymers are normally thermoplastic (four best answers): (a) acrylics, (b) cellulose acetate, (c) nylon, (d) phenolics, (e) polychloroprene, (f) polyesters, (g) polyethylene, (h) polyisoprene, and (i) polyurethane?
(a), (b), (c), and (g)
Which of the following polymers are normally thermoplastic (four best answers)? (a) acrylics, (b) cellulose acetate, (c) nylon, (d) phenolics, (e) polychloroprene, (f) polyesters, (g) polyethylene, (h) polyisoprene, and (i) polyurethane
(a), (b), (c), and (g)
Which of the following materials are used as fibers in fiber-reinforced plastics (four best answers): (a) aluminum oxide, (b) boron, (c) cast iron, (d) E-glass, (e) epoxy, (f) Kevlar 49, (g) polyester, and (h) silicon?
(a), (b), (d), and (f)
Which of the following contains significant amounts of aluminum oxide (three correct answers): (a) alumina, (b) bauxite, (c) corundum, (d) feldspar, (e) kaolinite, (f) quartz, (g) sandstone, and (h) silica?
(a), (b), and (c)
Among the thermosetting polymers, the most widely used commercially is which one of the following? (a) epoxies, (b) phenolics, (c) silicones, or (d) urethanes
(b)
Among the thermosetting polymers, the most widely used commercially is which one of the following: (a) epoxies, (b) phenolics, (c) silicones, or (d) urethanes?
(b)
As the temperature of a polymer increases, its density (a) increases, (b) decreases, or (c) remains fairly constant?
(b)
From which of the following ores is aluminum derived: (a) alumina, (b) bauxite, (c) cementite, (d) hematite, or (e) scheelite?
(b)
Plain carbon steels are designated in the AISI code system by which of the following: (a) 01XX, (b) 10XX, (c) 11XX, (d) 12XX, or (e) 30XX?
(b)
Plain carbon steels are designated in the AISI code system by which of the following? (a) 01XX, (b) 10XX, (c) 11XX, (d) 12XX, or (e) 30XX
(b)
The reinforcing phase is the matrix within which the secondary phase is imbedded: (a) true or (b) false?
(b)
Which of the following is the most important cast iron commercially: (a) ductile cast iron, (b) gray cast iron, (c) malleable iron, or (d) white cast iron?
(b)
Which of the following is the most important cast iron commercially? (a) ductile cast iron, (b) gray cast iron, (c) malleable iron, or (d) white cast iron
(b)
Which of the following plastics has the highest market share: (a) phenolics, (b) polyethylene, (c) polypropylene, (d) polystyrene, or (e) polyvinylchloride?
(b)
Which one of the following comes closest to expressing the chemical composition of clay: (a) Al2O3, (b) Al2(Si2O5)(OH)4, (c) 3AL2O3-2SiO2, (d) MgO, or (e) SiO2?
(b)
Which one of the following is generally the most porous of the clay-based pottery ware: (a) china, (b) earthenware, (c) porcelain, or (d) stoneware?
(b)
Which one of the following is the chemical formula for the repeating unit in polyethylene: (a) CH2, (b) C2H4, (c) C3H6, (d) C5H8, or (e) C8H8?
(b)
Which one of the following metals has the lowest density: (a) aluminum, (b) magnesium, (c) tin, or (d) titanium?
(b)
Which one of the following metals has the lowest density? (a) aluminum, (b) magnesium, (c) tin, or (d) titanium
(b)
Traditional brass is an alloy of which of the following metallic elements (two correct answers): (a) aluminum, (b) copper, (c) gold, (d) tin, and (e) zinc?
(b) and (e)
Glass ceramics are polycrystalline ceramic structures that have been transformed into the glassy state: (a) true or (b) false?
(b). Glass ceramics are glasses that have been transformed into a mostly crystalline form through heat treatment.
As the degree of crystallinity in a given polymer increases, the polymer becomes denser and stiffer, and its melting temperature decreases: (a) true or (b) false?
(b). Melting temperature increases with higher degree of crystallinity.
A steel with 1.0% carbon is known as which one of the following: (a) eutectoid, (b) hypoeutectoid, (c) hypereutectoid, or (d) wrought iron?
(c)
Anisotropic means which one of the following: (a) composite materials with composition consisting of more than two materials, (b) properties are the same in every direction, (c) properties vary depending on the direction in which they are measured, or (d) strength and other properties are a function of curing temperature?
(c)
Synthetic diamonds date to (a) ancient times, (b) 1800s, (c) 1950s, or (d) 1980.
(c)
Which of the following metals has the highest density: (a) gold, (b) lead, (c) platinum, (d) silver, or (e) tungsten?
(c)
Which of the following metals has the highest density? (a) gold, (b) lead, (c) platinum, (d) silver, or (e) tungsten
(c)
Which one of the following is fired at the highest temperatures: (a) china, (b) earthenware, (c) porcelain, or (d) stoneware?
(c)
Which one of the following materials is closest to diamond in hardness: (a) aluminum oxide, (b) carbon dioxide, (c) cubic boron nitride, (d) silicon dioxide, or (e) tungsten carbide?
(c)
Wood is which one of the following composite types: (a) CMC, (b) MMC, or (c) PMC?
(c)
Which of the following metals are used as the matrix metals in nearly all WC cemented carbides and TiC cermets (two correct answers): (a) aluminum, (b) chromium, (c) cobalt, (d) lead, (e) nickel, (f) tungsten, and (g) tungsten carbide?
(c) and (e)
Which of the following properties or characteristics are inconsistent with the metals (two correct answers): (a) good thermal conductivity, (b) high strength, (c) high electrical resistivity, (d) high stiffness, and (e) ionic bonding?
(c) and (e)
Which of the following properties or characteristics are inconsistent with the metals (two correct answers)? (a) good thermal conductivity, (b) high strength, (c) high electrical resistivity, (d) high stiffness, and (e) ionic bonding
(c) and (e).
The chemical formula for polyisoprene in natural rubber is which of the following: (a) CH2, (b) C2H4, (c) C3H6, (d) C5H8, or (e) C8H8?
(d)
The predominant phase in the iron-carbon alloy system for a composition with 99% Fe at room temperature is which one of the following: (a) austenite, (b) cementite, (c) delta, (d) ferrite, or (e) gamma?
(d)
Which one of the following is the most common element in the earth's crust: (a) aluminum, (b) calcium, (c) iron, (d) oxygen, or (e) silicon?
(d)
Which one of the following metals has the lowest melting point: (a) aluminum, (b) lead, (c) magnesium, (d) tin, or (e) zinc?
(d)
Which one of the following metals has the lowest melting point? (a) aluminum, (b) lead, (c) magnesium, (d) tin, or (e) zinc?
(d)
Which of the following materials are not composites (two correct answers): (a) cemented carbide, (b) phenolic molding compound, (c) plywood, (d) Portland cement, (e) rubber in automobile tires, (f) wood, and (g) 1020 steel?
(d) and (g)
Glass products are based primarily on which one of the following minerals: (a) alumina, (b) corundum, (c) feldspar, (d) kaolinite, or (e) silica?
(e)
Glass products are based primarily on which one of the following minerals? (a) alumina, (b) corundum, (c) feldspar, (d) kaolinite, or (e) silica
(e)
The leading commercial synthetic rubber is which one of the following: (a) butyl rubber, (b) isoprene rubber, (c) polybutadiene, (d) polyurethane, (e) styrene-butadiene rubber, or (f) thermoplastic elastomers?
(e)
Which one of the following is not a common alloying ingredient in steel: (a) chromium, (b) manganese, (c) nickel, (d) vanadium, (e) zinc?
(e)
Which one of the following is not a common alloying ingredient in steel? (a) chromium, (b) manganese, (c) nickel, (d) vanadium, (e) zinc
(e)
Ceramic matrix composites are designed to overcome which of the following weaknesses of ceramics (two best answers): (a) compressive strength, (b) hardness, (c) hot hardness, (d) modulus of elasticity, (e) tensile strength, and (f) toughness?
(e) and (f)
5 categories of steel groups
1. Plain carbon steels 2. Low alloy steels 3. Stainless steels 4. Tool steels 5. Specialty steels
Cemented carbides are what class of composites?
A cemented carbide is a cermet; although the cemented carbide industry does not generally think of cemented carbides as cermets, they fit within the definition.
What is a cermet?
A cermet is a composite material consisting of a ceramic and a metal. In the text, it is defined as a composite consisting of ceramic grains imbedded in a metallic matrix.
What is a copolymer?
A copolymer is a polymer made up of two different types of mers, such as ethylene and propylene.
Describe the difference in mechanical properties as a function of temperature between a highly crystalline thermoplastic and an amorphous thermoplastic.
A highly crystalline TP retains rigidity during heating until just before its Tm is reached. An amorphous TP shows a significant drop in deformation resistance as its Tg as temperature is reached; it becomes increasingly like a liquid as temperature continues to increase.
What is a hybrid composite?
A hybrid composite is a fiber-reinforced PMC in which two or more fibers materials are combined in the FRP.
What is a plasticizer?
A plasticizer is a chemical added to the polymer to make it softer and more flexible. It is often added to improve the polymer's flow characteristics for shaping.
What is a polymer?
A polymer is a compound comprised of long-chain molecules that consist of repeating units, called mers, connected end to end.
What is a terpolymer?
A terpolymer is a polymer with three different mer types. An example is ABS (acrylonitrile-butadiene-styrene) plastic.
What is a whisker?
A whisker is a thin, hairlike crystal of very high strength.
Implementation of lean principles on a broad scale; has Flexibility (quick response to market)
Agile Manufacturing
a mixture or compound of two or more elements, at least one of which is metallic
Alloy
used in various applications from abrasives to artificial bones
Alumina-aluminum oxide (AlO23)
What does the term advanced composites mean?
An advanced composite is a PMC in which carbon, Kevlar, or boron fibers are used as the reinforcing material.
What happens to an elastomer when it is below its glass transition temperature?
An elastomer becomes hard and brittle when its temperature is below its Tg.
What does the term anisotropic mean?
Anisotropic means that the properties of a material vary depending on the direction in which they are measured.
What is one of the important applications of titanium nitride, as mentioned in the text?
As a thin coating on cutting tools to prolong tool life.
How does the designation scheme for copper work?
Based on the Unified Numbering System for Metals and Alloys (UNS)
What is unique about the polymer cellulose?
Cellulose is a polymer that grows in nature. Wood fiber contains about 50% cellulose and cotton fiber is about 95% cellulose.
What is clay, used in making ceramic products?
Clay most commonly consists of hydrous aluminum silicate; for example, kaolinite (Al2(Si2O5)(OH)4) is a common clay.
A materials system composed of two or more distinct phases whose combination produces aggregate properties different from those of its constituents
Composite Material
items produced by continuous processes, such as sheet metal coil (almost), oil refinery
Continuous Products
What type of atomic bonding characterizes the ceramics?
Covalent and ionic bonding
What is cross-linking in a polymer, and what is its significance?
Cross-linking is the formation of connections between the long-chain molecules in a polymer. It causes the polymer structure to be permanently altered. If the amount of cross-linking is low, the polymer is transformed into an elastomer; if cross-linking is significant, the polymer is transformed into a thermoset.
How are a polymer's properties affected when it takes on a crystalline structure?
Density, stiffness, and melting temperature increase.
What does the term devitrification mean?
Devitrification is the transformation from the glassy state into a polycrystalline state.
individual parts, such as nails, gears, bearing balls, cans, engine blocks
Discrete Products
Elastomers and thermosetting polymers are both cross-linked. Why are their properties so different?
Elastomers are lightly cross-linked, whereas thermosets are highly cross-linked. Light cross-linking allows extensibility; a highly cross-linked structure makes the polymer rigid.
Give some examples of commercial products which are laminar composite structures.
Examples given in Table 9.2 are automotive tires, honeycomb sandwich structures, fiber reinforced polymer structures such as boat hulls, plywood, printed circuit boards, snow skis made from fiber reinforced polymers, and windshield glass.
Properties of Aluminum
Excellent corrosion resistance, very ductile metal, competitive with steels when heat treated
Name some of the important applications of FRPs.
FRPs are used in modern aircraft as skin parts, automobile body panels, printed circuit boards, tennis rackets, boat hulls, and a variety of other items.
Metals that arealloys of iron and carbon; includes steel and cast iron
Ferrous
Why are fillers added to a polymer?
Fillers are added to increase strength or simply to reduce the cost of the polymer.
How does the designation scheme for magnesium work?
First 2 characters identify principal alloying elements, 2 numbers that indicates the amounts of the two alloying ingredients to nearest percent, and last symbol is a letter that indicates variation in composition
What is graphite?
Graphite is carbon in the form of hexagonal crystalline layers, in which covalent bonding exists between atoms in the layers, and the (parallel) layers are bonded by van der Waals forces, thus leading to highly anisotropic properties.
Low carbon steels have a _________ strength, hardness, hot hardness, wear resistance, and toughness than plain carbon steels
Higher
What are some of the principal applications of cemented carbides, such as WC-Co?
Important applications of WC-Co include cutting tool inserts, drawing dies, rock drilling bits, dies for powder metallurgy, and other applications where hardness is a critical factor.
How do the properties of polymers compare with those of metals?
In general, polymers have lower strength, hardness, stiffness, density, and temperature resistance compared to metals. In addition, polymers have low electrical and thermal conductivity.
What are the 3 groups of superalloys?
Iron, Nickel, and Cobalt based alloys
What does the degree of polymerization indicate?
The degree of polymerization indicates the average number of mers or repeating units in the polymer molecule.
What is the basic difference between low-density and high-density polyethylene?
LDPE has a branched structure and is amorphous. HDPE is linear and highly crystalline. These differences account for HDPE having higher density, stiffness, and melting point.
A methodology to minimize waste at all levels through assessment of each activities of a company
Lean Manufacturing
Properties of Magnesium
Lightest of the structural metals, easy to machine, is relative soft and lacks sufficient strength, strength-to-weight ratio is an advantage
Name the three basic categories of composite materials.
Metal matrix composites (MMCs), ceramic matrix composites (CMCs), and polymer matrix composites (PMCs).
includes all metallic elements and their alloys that are not based on iron
Non Ferrous
In addition to fillers and plasticizers, what are some other additives used with polymers?
Other additives include (1) lubricants - to reduce friction and improve flow; (2) flame retardents; (3) colorants; (4) cross-linking agents, (5) antioxidants, and (6) ultraviolet light absorbers.
What are the four most common elements in the earth's crust?
Oxygen, silicon, aluminum, and iron
Identify some of the important properties of fiber-reinforced plastic composite materials.
Properties include high strength-to-weight ratio, high modulus-to-weight ratio, low density, good fatigue strength, good corrosion resistance, and low thermal expansion for many FRPs.
What does the term refractory mean?
Refractories are heat resistant ceramic materials. The term is sometimes also applied to metals that are heat resistant.
What are the elements in the ceramic material Sialon?
Sialon consists of the elements silicon, aluminum, oxygen, and nitrogen.
What is the primary mineral in glass products?
Silica, or silicon dioxide (SiO2).
The main ingredient in most glass products
Silica, silicon dioxide (SiO2)
What are the two main categories of alloys
Solid solutions and intermediate phases
These are highly alloyed steels designed for corrosion resistance
Stainless steels
a group of high-performance alloys designed to meet very demanding requirements for strength and resistance to surface degradation (corrosion and oxidation) at high service temperatures.
Superalloys
A philosophy to balance the requirements of economy, environment, and society
Sustainable Manufacturing
How do thermoplastic elastomers differ from conventional rubbers?
TPEs are different in two basic ways: (1) they exhibit thermoplastic properties, and (2) their extensibility derives from physical connections between different phases in the polymer rather than cross-linking.
What are some of the factors that influence a polymer's tendency to crystallize?
The factors that influence a polymer's tendency to crystallize are the following: (1) only linear polymers can form crystals; (2) copolymers do not form crystals; (3) stereoregularity - isotactic polymers always form crystals, atactic polymers never form crystals, and syndiotactic polymers plasticizers inhibit crystal formation; and (6) stretching the polymer tends to promote crystallization.
What do the digits in the AISI-SAE designation scheme represent? (for example YYXX)
The first 2 numbers designate the type of steel (10=plain carbon steel) and the second 2 numbers designate the % carbon it contains.
What are the common forms of the reinforcing phase in composite materials?
The forms are: (1) fibers, (2) particles and flakes, and (3) an infiltrated phase in skeletal structures.
Copolymers can possess four different arrangements of their constituent mers. Name and briefly describe the four arrangements.
The four possible arrangements of the mers along the chain are (1) alternating, in which the mers repeat every other position; (2) random, in which the mers are in random order; (3) block, in which mers of each type group themselves into long segments along the chain; and (4) graft, in which mers of one type are attached as branches to a main backbone of mers of the other type.
What are some of the functions of the ingredients that are added to glass in addition to silica? Name at least three.
The functions of the additional ingredients include: (1) acting as flux (promoting fusion) during heating; (2) increasing fluidity in the molten glass during processing; (3) retarding devitrification, which is the tendency to crystallize from the glassy state; (4) reducing thermal expansion in the final product; (5) increasing the chemical resistance against attack by acids, basic substances, or water; (6) adding color to the glass; and (7) altering the index of refraction for optical applications (e.g., lenses).
What is meant by the term interface in the context of composite materials?
The interface is the boundary between the component phases in a composite material.
What is the primary polymer ingredient in natural rubber?
The primary polymer ingredient in natural rubber is polyisoprene whose mer has the chemical formula C5H8.
What is the rule of mixtures?
The rule of mixtures applies to certain properties of composite materials; it states that the property value is a weighted average of the property values of the components, the weighting being by proportions of the components in the composite.
Cross-linking (curing) of thermosetting plastics is accomplished by one of three ways. Name the three ways.
The three ways are (1) temperature-activated systems, in which elevated temperatures accomplish curing; (2) catalyst-activated systems, in which small amounts of a catalyst cause cross-linking; and (3) mixing-activated systems, in which two reactive components are mixed and curing occurs by their chemical reaction.
What are the two forms of sandwich structure among laminar composite structures? Briefly describe each.
The two forms are (1) foamed-core sandwich, in which the core is polymer foam between two solid skins; and (2) honeycomb, in which the core is a honeycomb structure sandwiched between two solid skins.
How do the properties of thermosetting polymers differ from those of thermoplastics?
Thermosets are more rigid, brittle, capable of higher service temperatures, and cannot be remelted.
What are the three general factors that determine the properties of a composite material?
Three factors are given in the text: (1) the component materials; (2) the geometric shapes of the constituents - the reinforcing phase in particular - and the resulting structure of the material; and (3) the interaction of the phases.
clay products such as pottery, bricks, common abrasives, and cement
Traditional ceramics
What is the difference between the traditional ceramics and the new ceramics?
Traditional ceramics are based primarily on clay products (e.g., pottery, bricks) while new ceramics are more recently developed ceramics which are generally simpler in chemical composition (e.g., oxides, carbides).
How are traditional composites distinguished from synthetic composites?
Traditional composites have been used for decades or centuries; some of them are obtained from sources in nature, such as wood. Synthetic composites are manufactured.
What are the general physical properties of ceramic materials?
Typical physical properties include electrical and thermal insulating, medium density (mostly below the density of metals), high melting temperatures, and thermal expansion usually less than metals.
Identify some of the characteristic properties of composite materials
Typical properties include (1) high strength-to-weight and stiffness-to-weight ratios; (2) good fatigue properties and toughness; (3) anisotropic properties in many cases; and (4) other properties and features that are difficult or impossible to obtain with metals, ceramics, or polymers alone.
What are some of the weaknesses of ceramics that might be corrected in fiber-reinforced ceramic matrix composites?
Weaknesses of ceramics include low tensile strength, poor toughness, and susceptibility to thermal cracking.
