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Met 121 Test 4

Test 4 study guide Missouri S&T Spring 2011

Assets of aluminum are Lightweight, easy to fabricate, and good electrical and thermal conductivity
Limitations of aluminum are poor wear resistance, low stiffness, poor in fatigue.
Aluminum and aluminum alloys are: fabrication friendly
Wrought alloys are: shaped as a solid.
Desirable attributes of wrought alloys are low yield strength, high ductility, good strain hardening.
The designation system for wrought aluminum alloys involves a: four-digit number
The suffix in the aluminum designation system designates the material: condition (past processing history)
An aluminum alloy with a three-digit designation number is a: cast aluminum alloy
Attractive properties for casting alloys include: low melting point, good fluidity, high as-solidified strength
High strength aluminum alloys are heat treatable
The best corrosion resistance is found in aluminum alloys that are: non heat treatable
The most effective strengthening method for aluminum alloys is: age hardening
(True/false) A high-strength aerospace aluminum alloy has strength equivalent to a quenched-and-tempered medium carbon steel. false
(True/False) Casting alloys can be heat treated after casting for added strength. True
In the color anodizing process, the material being colored is: Al oxide
What are some assets of aluminum-lithium alloys stronger, lighter, stiffer
Attributes of magnesium Does not respond well to strengthening methods, strength to weight is good, it’s lighter than aluminum.
Limitations of magnesium alloys poor wear resistance, poor elevated temp strength, poor fatigue resistance
(T/F) Magnesium can be cast to final shape provided the molten metal and hot solid is isolated from oxygen by some form of protective atmosphere and special mold materials are used. True
Beryllium is unique among the engineering metals because of its extremely high: Elastic Modulus
Titanium has a density that is: Between steel and aluminum
(T/F) The corrosion resistance of titanium is due to an adherent oxide, much like Al. True
Orthopedic implants and bone-repair screws and plates often use this material since it is strong, light weight and corrosion resistant to body fluids. Titanium
Color anodizing is a surface finishing treatment that is somewhat unique to this metal Al
This metal can be very difficult to fabricate. It is brittle at room temp (HCP). Machining chips can burn: and molten metal must be kept under protective atmosphere. Mg
This metal is sometimes used for nuclear applications because it is relatively transparent to the movement of neutrons Beryllium
This metal is lighter than Al, but stiffer than steel Be
Because the YSstrongest/YSweakest ratio is only 3, design engineers must design to the material, rather than the material accommodating the design. Mg
It is the only high temp lightweight metal, retaining useful strength to 900 F. Ti
It is often used in place of aluminum when use involves elevated temp, or in place of steel for weight savings. Ti
It has the lowest density of all of the engineering metals (i.e. is lightest) Magnesium
People specifying the use of this metal are driven by a desire for light weight, and are willing to accept the numerous negative properties and characteristics. Mg
Since this material is allotropic (BCC at elevated temp and HCP at room temp), it can be heat treated by both age hardening and phase transformation processes. Ti
It offers the strength of a heat-treated medium-carbon steel at almost half the weight Ti
Because of its FCC structure, it has the highest ductility of the lightweight metals Al
Because this metal is considered to be toxic, processing often requires special precautions Be
Its unusual designation system consists of two letters followed by two or three numbers, such as AZ61 or AM100. Magnesium
Because of its FCC crystal structure, copper and copper alloys have: excellent formability
Copper is the standard to which other materials are compared to rate: conductivity
The good corrosion resistance of copper and nickel is: An inherent property of the metal
When exposed to extremely low temps, copper and copper alloys: do not embrittle
Copper and copper alloys are: Heavier than steel
The primary uses of copper are related to its: Conductivity and corrosion resistance
This material has “better corrosion resistance to more media than any other commercial alloy.” Monel
This alloy is one of the most popular “low thermal expansion” alloys. Invar
The electrical resistance heating wires for toasters are often made from this material: Nickel-chromium
Copper (is, is not) considered to be an elevated temp material. Is not. Ti, Ni, and Cobalt are
This is the only light-weight high-temp metal. Titanium
Tungsten, Molybdenum, and Tantalum are____? Refractory metals
Which properties are necessary for the coatings applied to refractory metals? High melting point, matching thermal expansion, diffusion barrier to various gases
Nickel and cobalt form the basis of this group Superalloys
Protective coatings are required in order for this material to function at extremely high temperatures (approaching 3000 F) Refractory metals
All members of this group have the BCC structure and are heavier than steel refractory metals
This metal has the best overall electrical and thermal conductivity, along with good formability and corrosion resistance Copper
This metal has good strength and corrosion resistance at elevated temperatures coupled with good formability (due to its FCC structure) Nickel
Because of the range of colors, alloys of this metal are often used in architectural and artistic applications copper
This group has the highest operating temps of the engineering metals Refractory Metals
Metals from this group can be used at elevated temps up to 2000 F superalloys
Ceramic materials have _________ atomic bonding. Ionic or Covalent
The crystal structures of ceramic materials are often quite complex because: Atoms of different sizes are in the same structure, charge neutrality must be maintained throughout ionic structures, and covalent structures often have a limited number of nearest neighbors.
The equilibrium structure in ceramic materials (lowest energy) is: Crystalline
If we cool faster than the critical cooling rate that separates glass and crystalline ceramics, we are likely to produce a: glass
While crystalline ceramic materials contain dislocations, they do not exhibit plastic deformation because: dislocation movement is difficult and fracture occurs at a lower stress
Full theoretical density is difficult to achieve in processed ceramics because: Voids remain between the particles after sintering
According to the principles of fracture mechanics, brittle materials will fail when: The combination of load (stress) and flaw size reaches a critical value.
The fracture resistance of a ceramic material is best improved by: Decreasing the flaw size
While it is unlikely that we will be able to change the ______ of ceramic materials, it may be possible to impart significant amounts of _____. Brittleness, toughness
Tempered glass has enhanced fracture resistance because it incorporates: Compressive residual stresses on the surface induced by quenching.
Cermets gain their enhanced toughness through: A metal matrix
Transformation toughening involves: A metastable phase that changes structure and expands when a crack comes near.
In this toughening mechanism, ceramic materials are alloyed to eliminate any phase changes over the entire range of expected operating temperatures. Stabilization
For elevated temperature creep resistance, a crystalline ceramic should have ____ crystals. Large
Crystalline ceramic products are usually fabricated by: Pressing and sintering(firing) solid particles
Ceramic materials excel when: Physical properties dominate the selection process.
Ceramics used in products like sandpaper, grinding wheels, and cutting tools are called: Abrasives
Ceramic materials that are used for applications like the containment of molten metals are: Refractories
The white “Corelle” dinnerware and Corningware baking pans are examples of: Glass Ceramics
Good corrosion resistance and elevated temperature strength are an asset of what group of ceramic materials? Advanced ceramics
The wide variation in mechanical properties for nominally “identical” ceramic components (same material and same processing) can be attributed to: Variation in the size, shape and location of flaws.
While a ceramic engine block would allow higher operating temps, and eliminate the need for cooling, a major barrier is likely to be: The material will still be brittle.
List four attractive properties of polymeric materials. Ease of fabrication, can have integral color, good corrosion resistance, and light weight.
The bonding mechanism between the atoms along the spine of linear polymers is: Covalent
Increasing the amount of initiator or activator in an addition polymerization reaction will ____ the length of the chains and ____ the strength of the resulting polymer. Decrease, Decrease
The functionality of polymer reactants that form linear or chain-type polymers is: Two
The functionality of polymer reactants that form 3-dimensional network polymers is: three or more
The “degree of polymerization” refers to the: Average number of mers per molecule
Two different types of monomers or reactants are required for this type of polymerization that involves the production of a small by-product molecule. Condensation polymerization
The recyclable plastics are of what type of polymer? Thermoplastic polymers
The highest rigidity is found in this type of polymer Thermosetting
Heating softens, cooling hardens, and the cycle can be repeated with this type of polymer. Thermoplastic
High strength polymers would most likely be of this type. Thermosetting
This type of polymer is the most easily recycled. Thermoplastic
Extremely large elastic deformations are possible with this class of polymers Elastomeric
Extremely large plastic deformations are possible with this class of polymers Thermoplastic
An adhesive example of this class of polymers would be two-part epoxy Thermosetting
An adhesive example of this class of polymers would be hot-melt glue Thermoplastic
An adhesive example of this class of polymers would be flexible silicone bathtub caulk Elastomeric
Will increasing the length of the average change increase or decrease the strength of a thermoplastic polymer? Increase
Will replacing hydrogen side atoms with chlorine increase or decrease the strength of a thermoplastic polymer? Increase
Will plastically deforming or “cold working” increase or decrease the strength of a thermoplastic polymer? Increase
Will inducing extensive branching of the chains increase or decrease the strength of a thermoplastic polymer? Decrease
Will inducing “crystallization” during cooling increase or decrease the strength of a thermoplastic polymer? Increase
(True/False) The strength of a “high-strength” polymer is equivalent to that of an engineering metal. False
(True/False) The rigidity of a rigid polymer is similar to that of an engineering metal. False
(True/False) Adhesive bonding is an attractive means of joining dissimilar materials. True
(True/False) Adhesive joints often compensate for their lower strength by increasing the area of the bond. True
(True/False) Adhesive bonding is an attractive means of joining materials that will be used at elevated temperatures False
(True/False) Adhesives can provide an electrical and thermal insulating barrier in a joint. True
What type of composite are two or more distinct layers present Laminar
“Aspect ratio” characterizes one of the components in this type of composite Fiber-reinforced
What type of composite is anisotropic behavior always expected in Laminar
The primary purpose of this type of composite is to retain strength to higher operating temperatures—SAP and TD-nickel are common examples. Dispersion-Strengthened Particulate
This type of composite is often used when the objective is improved wear or corrosion resistance Laminar
Small amounts of tiny oxide particles are dispersed throughout a matrix in this type of composite Dispersion-strengthened particulate
Examples of this type of composite are U.S. sandwich coinage, honeycomb, and corregated cardboard Laminar
Examples of this type of composite are grinding wheels, concrete, and cemented carbides True Particulate
Examples of this type of composite include graphite-epoxy golf-club shafts and steel-belted radial automobile tires Fiber-reinforced
This type of composite is most likely to exhibit isotropic properties Particulate
A significant difference in thermal expansion is essential to the performance of: Bimetallics
Alclad is a laminar composite consisting of: A corrosion-resistant aluminum skin over a high-strength aluminum core
In fiber-reinforced composites, the role of fibers is to: Carry load and impart stiffness
We generally want the matrix material in a fiber or particulate composite material to be: Strong, tough and ductile
3 attractive properties of fiber reinforced composites are: Light Weight, Good Fatigue Life, and High Strength and Stiffness
3 limitations to the use of fiber composites are: Difficulty of inspection, limited repairability, and limited joining options
“Specific strength” is defined as the ratio of yield strength to ____. Density
“Aspect ratio” is the ratio of: Fiber length to diameter
The strength of a composite typically increases when the aspect ratio is: Increased
The strength of a fiber-reinforced composite would be expected to increase if we: Increase the volume fraction of fibers, reduce the diameter of the fibers, and/or align the fibers in the direction of maximum stress
Attractive properties of Kevlar fibers include: High strength, light weight, and a negative coefficient of thermal expansion.
In polymer-matrix fiber-reinforced composites the polymer matrix: Can be either thermoplastic or thermosetting
Weak bonding between the fiber and matrix is actually an asset in the performance of ___ matrix fiber-reinforced composites. Ceramic
The rule of mixtures estimates a composite property by computing a weighted average based on the ____ of the various components. Volume fraction
A rule of mixtures calculation will give an accurate prediction of: Density
Over 90% of all corrosion is _______ in nature. Electrochemical (Galvanic)
In a galvanic corrosion cell, corrosion occurs at the _____ where electrons are ______. Anode, created.
What is a composition cell? 2 DISSIMILAR metals are in contact to complete a galvanic cell. One of the metals become anode and corrodes and other becomes cathode and is protected.
Cast iron to copper water pipe, and steel nails in aluminum siding are an example of _____ cells. Composition
Differences in the form of chemistry yield a ______ cell. Composition
Environmental differences yield ______ cells. Concentration
Loading differences yield ______ cells. Stress
What happens in concentration cell? Concentration differences in the electrolyte induce galvanic action. Ex: Oxygen concentration cell: Where concentration of oxygen in electrolyte is lowest, the metal adjoining the electrolyte becomes the anode and corrodes.
Soil line corrosion, crevice corrosion, and moss on pipeline are examples of ______ cells. Concentration
Explain stress cells If you have stress that varies from location to location in a metal. The highest stress location acts as anode and corrodes.
Nails corroding at heads and tips with unattacked shanks are examples of corrosion caused by _______ cells. stress
Three good ways to reduce corosion are. Break the electrical contact, use a sacrificial anode, and use various coatings.
Cobalt is considered to be a _______. Superalloy
If we wish to increase the strength of a chain-type polymer, we can ____ the amount of activator or catalyst to ___ the average length of the chain molecules. Decrease, Increase
In order to produce a network or framework polymer, we must have reacting mers with a functionality of ____. Three or more
If we progressively increase the degree of cross-linking in a polymer, we would expect the material to become ____ and _____ ductile. Stronger, less
When producing a laminar material, such as corrugated cardboard or honeycomb, our objective is often to impart: Enhanced strength and stiffness
In a fiber-reinforced composite, we usually expect ductility and toughness to be imparted by the: Matrix
What does the rule of mixtures do? Predicts properties as a weighted average of th properties of the components.
When two materials from galvanic series come into contact the one _____ in the series is expected to experience acceleration of corrosion. Higher in the series.
Age hardened aluminum has been characteried as having poorer corrosion resistance than the weaker, single-phase, non-heat-treatable alloys. This is because the heat-treatable alloys are a form of ______ corrosion cell. Composition
Created by: jamey_270