MSE 350 Exam #3

What wt% C range is preferable for tool steel? 0.6-0.75 wt% 18-19 wt% 2.57-4.26 wt%

0.6-0.75 wt%

If a Cast Iron has designation of ASTM 60-40-18(UNSF32800), the yield Strength is: 328,000 psi 40,000 psi 18,000 psi 60,000 psi

40,000PSI

Which of the following aluminum alloys should you consider the primary candidate for a design where specific yield strength is the most critical design factor? (Use Table 13.8) 8090 T651 2090-T83 7075 T6 2024-T4

7075 T6

In an Acid Electrolyte fuel cell with hydrogen fuel; select the statement that is not right. Hydrogen is oxidized to produce hydrogen ions at the anode The acid electrolyte is mainly phosphoric acid. It has a resistance for electron transfer, but allows hydrogen ion diffusion The cathode reaction is Oxygen reduction in acidic solution The cathode reaction is Oxygen oxidation in acidic solution

The cathode reaction is Oxygen oxidation in acidic solution

Select the statement that IS NOT RIGHT; The major limitation of titanium is its chemical reactivity with other materials at elevated temperature. The corrosion resistance of titanium alloys at normal temperatures is unusually high. Titanium alloys are commonly used in airplane structures, space vehicle, and surgical implants and in the petroleum and chemical industries. The corrosion resistance of titanium alloys at normal temperatures is unusually low.

The corrosion resistance of titanium alloys at normal temperatures is unusually low.

In an n type extrinsic semiconductors, select the right answer The electrons are majority carriers and holes are the minority charge carriers The electrons are minority carriers and holes are the majority charge carriers

The electrons are majority carriers and holes are the minority charge carriers

Which is a good use of "pressure vessel steel"? Construction I-Beam Automotive crankshaft Kitchen knife Scuba oxygen tank

scuba oxygen tank

A design requires a TiNi wire to be shaped like the letter S at an operating temperature of 100C (212F). The selected alloy Austenite Ms is 90C (194F) and the Mf is at 60C (140F). The wire was drawn (manufactured) straight at a temperature of 500C (932F), and the wire supplied is straight. The wire is easily bent into the required S shape at room temperature. What will be the shape of the wire at the operating temperature of 100C (212F). S shaped C shaped The shape is impossible to know. Straight

straight

(True or False) In semicoductors there are two types of electronic charge carriers: Free Electron - negative charge - in conduction band Hole - positive charge - vacant electron state in the valence band

true

Carbon nanotubes - sheet of graphite rolled into a tube, ends capped with fullerene hemispheres.(true or false)

true

Using the Standard Electromotive Force (EMF) table, calculate the standard potential of Zn-Cu Cell (the so called Daniel cell) 1.1 V 0.34 V 0.76 V 0.32 V

1.1V

The bandgap is important to the optical properties of semiconductors because the process of absorbing light requires electrons to move from an occupied state to an unoccupied state. Light arrives in discrete bunches called photons with energies that are inversely proportional to their wavelengths. The energy E of a photon with wavelength Lamda is: E = h(c/Lamda) Here c is the speed of light, 300,000 km/s. h is Plank constant 6.62*10^-34 Js. Be careful with units! The most convenient units for E are electron volts, with 1 eV=1.6 * 10-19 J. What is the minimum wavelength absorbed by Ge, for which Eg = 0.67 eV? 1860 nm 1.86 nm 827 nm 18.6 micometer

1860 nm

The Specific yield strength of Ti-8Al-1Mo-1V (UNS R54810) Annealed, is ; 204 MPa 130 MPa 220 MPa

204 MPa

When we have two dissimilar metals are in contact with each other, the so called Galvanic Couple, and they are in a liquid electrolyte, What is the best ratio of the area of Anode to the area of Cathode >>1 <<1 =1

>>1

Select the statement that is not true; A battery is one or more electrochemical cells that produce electrical energy. A single electrochemical cell produces around 2.10V. A 12V battery is six lead-acid cells in series. A single lead-acid cell produces around 12.10V. A 12V battery is six lead-acid cells in series. A lead-acid battery (used in automobiles) have a lead anode, a lead oxide (PbO2) cathode and a Sulfuric acid electrolyte.

A single lead-acid cell produces around 12.10V. A 12V battery is six lead-acid cells in series.

Which of the following aluminum alloys can be welded AA6061 AA2024 AA 5052 AA7075

AA 5052

Suppose we have added an impurity atom from the group VA column of the periodic table ( i.e., P, As, and Sb), to Si, select the right answer A p-type extrinsic semiconductor is formed An n-type extrinsic semiconductor is formed A p-type intrinsic semiconductor is formed An n-type intrinsic semiconductor is formed

An n-type extrinsic semiconductor is formed

Why we can have the metals in everyday use if almost all of them have a natural tendency to become oxidized? Because metals have relatively high densities. Because they form an oxide on the surface. Because metals have relatively high melting temperature. Because metals are strong.

Because they form an oxide on the surface.

In the Transformations which involve nucleation and growth stages, the TTT diagram is, C shape S shape sigmoidal linear

C shape

Using the equation 11.5 in the book, driving force to nucleate increases as we; Decreasing the supercooling (deltaT) Decrease the temperature. Increase the temperature.

Decrease the temperature.

During the growth process, increasing supercooling (DeltaT) Decreases the diffusion of atoms Increases the diffusion of atoms Does not affect diffusion of atoms initially increase and then decrease diffusion of atoms

Decreases the diffusion of atoms

For metals, which of the following does not increase resistivity? addition of imperfections Decreasing the temperature Increasing the temperature plastic deformation

Decreasing the temperature

Select one of the statement below that is not associated with Engineering plastics. A relatively high strength and Elastic modulus. A relatively high toughness Retention of mechanical properties over a range of temperatures. Dimensional change over usage temperature range.

Dimensional change over usage temperature range.

Suppose we have added an impurity atom from the group VA column of the periodic table ( i.e., P, As, and Sb), to Si, select the right answer Donor atoms and Donor states will be created Acceptor atoms and Acceptor states will be created

Donor atoms and Donor states will be created

What is the crystalline structure of "Tough at subzero steel"? BCC FCC SC

FCC

Which statement does not apply to Cast Irons: Cementite decomposes to ferrite + graphite Fe3C --> 3 Fe (α) + C (graphite) -generally a slow process Ferrous alloys with > 2.1 wt% C -more commonly 3 - 4.5 wt% C Ferrous alloys with Cr>11% Low melting - relatively easy to cast Generally brittle

Ferrous alloys with Cr>11%

Which one is not true about advanced Ceramics for Automobile engines? Higher weights than current engines Operate at high temperatures - high efficiencies Low frictional losses, Operate without a cooling system Lower weights than current engines

Higher weights than current engines

Select the statement that IS NOT RIGHT; Highly amorphous and pore-free polymer materials are transparent Highly crystalline polymers may be opaque Semicrystalline polymers may be translucent, Highly amorphous and pore-free polymer materials are opaque

Highly amorphous and pore-free polymer materials are opaque

Select the answer that IS NOT TRUE for Stainless Steels If th AISI designation of a stainless steel begins with a 4, it has ferritic (BCC) crystal structure. If th AISI designation of a stainless steel begins with a 3, it has ferritic (BCC) crystal structure. In stainless steels, Ni is added to stabilize Austenitic phase Stainless steels are alloys of Iron with >11%Cr

If th AISI designation of a stainless steel begins with a 3, it has ferritic (BCC) crystal structure.

Select the statement that IS NOT RIGT. If the polymer and solvents have similar structure, mixing is less likely to occur. Large amounts of solvent mixing with a polymer leads to polymer dissolving in the solvent. Amorphous polymers: More likely to mix with solvents than crystalline polymers. Small amount of solvent mixing with a polymer leads to polymer swelling.

If the polymer and solvents have similar structure, mixing is less likely to occur.

For Ruby = Sapphire (Al2O3) + (0.5 to 2) at% Cr2O3, select the statement that IS NOT RIGHT; In Ruby red light is absorbed Adding 0.5to 2% Cr2O3 to Sapphire alters the band gap to make red Ruby Aluminum Oxide single crystals are transparent and colorless Sapphire. In Ruby blue and orange/yellow/green light is absorbed

In Ruby red light is absorbed

Select the statement that is NOT RIGHT; In cathodic protection of a metal structure, the structure is connected to the negative terminal of a battery When the surface of the reactive metal titanium is passivated, titanium dioxide forms on the surface of the metal. When iron is galvanized, it is coated with zinc. In cathodic protection of a metal structure, the structure is connected to the positive terminal of a battery

In cathodic protection of a metal structure, the structure is connected to the positive terminal of a battery

Using the equation 11.3 in the book, critical radius for nucleation increases as we; Increase the temperature. Decrease the temperature. Increasing the supercooling (deltaT)

Increase the temperature.

In pure Silicon which is an intrinsic semi-conductor, which of the following does not increase resistivity? Increasing the temperature Increasing the amount of Cold Work Decreasing the temperature

Increasing the temperature

For the reflection of light for metals, select the statement that does not apply. Color of reflected light depends on wavelength distribution Large fraction of light may be absorbed Metal surfaces appear shiny Most of absorbed light is reflected at the same wavelength

Large fraction of light may be absorbed

Which of the following kinetics of oxidation is the most desirable one? linear Parabolic Logarithmic

Logarithmic

During Martensite transformation in iron-carbon alloys, dislocation form to accomodate distortion. Dislocations allow material to be continuous during distortion to martensitic structure. Formation of dislocations in a material is irreversible. Thus;(select the right answer) Martensitic transformation in iron-carbon alloys is a reversible process. Martensitic transformation in iron-carbon alloys is an irreversible process.

Martensitic transformation in iron-carbon alloys is an irreversible process.

Select the statement that IS NOT RIGHT. Open polymers (branched polyethylene) have lowe rates of diffusion than crystalline High-density polyethylene. Open polymers (branched polyethylene) have high rates of diffusion than crystalline High-density polyethylene. Atoms that are more soluble in a polymer have a high permeability. Permeation = Solubility of penetrating atoms in the host *Diffusivity of the penetrating atoms

Open polymers (branched polyethylene) have lowe rates of diffusion than crystalline High-density polyethylene.

Select the right statement; Pilling-Bedworth ratio of around 1: Oxide is sufficiently protective. Pilling-Bedworth ratio of less than 1 and more than 2: Oxide is not protective. Pilling-Bedworth ratio of around 1: Oxide is sufficiently protective. Pilling-Bedworth ratio of less than 1 and more than 2: Oxide is protective. Pilling-Bedworth ratio of around 1: Oxide is not protective

Pilling-Bedworth ratio of around 1: Oxide is sufficiently protective. Pilling-Bedworth ratio of less than 1 and more than 2: Oxide is not protective.

Which one is not among limitations of Ferrous alloys; Relatively low electrical conductivities Relatively low densities Generally poor corrosion resistance, except stainless steels Relatively high densities

Relatively low densities

Select the one that is NOT TRUE. Metals (Conductors): for metals empty energy states are adjacent to filled states. Insulators: wide band gap (> 2 eV) Semiconductors: -- narrow band gap (< 2 eV) Semiconductors: wide band gap (> 2 eV)

Semiconductors: wide band gap (> 2 eV)

Select the true statement. Shape-Memory effect is due to reversible Martensitic transformation in TiNi. Shape-Memory effect is due to an irreversible Martensitic transformation in TiNi.

Shape-Memory effect is due to reversible Martensitic transformation in TiNi.

Degree of protection that an oxide offers to an underlying metal depends on: (select the statement which is not right) the mechanical integrity of the oxide. Slower the rate of diffusion, more protective the oxide the rate of diffusion of metals ions or oxygen ions through the oxide Slower the rate of diffusion, less protective the oxide

Slower the rate of diffusion, less protective the oxide

Which one is not a polymer application type Fibers Coatings and Adhesive Spinning and extrusion Films and Foams

Spinning and extrusion

When we have two dissimilar metals in contact with each other, the so called Galvanic Couple, and they are in a liquid electrolyte, select the statement that is NOT RIGHT; The more Anodic metal will corrode. The more active metal will corrode. The more electropositive metal will corrode. The more Cathodic metal will corrode.

The more Cathodic metal will corrode.

A eutectoid steel is Austenitized and then is held at T1=700, and T2= 680 C (both in the pearlite region of TTT diagram), long enough until we have 100% pearlite. Select the proper answer The pearlite formed at T1 is stronger than the pearlite formed at T2. The pearlite formed at T1 is weaker than the pearlite formed at T2. The pearlite formed at T1 has exactly the same strength as the pearlite formed at T2.

The pearlite formed at T1 is weaker than the pearlite formed at T2.

A eutectoid steel is Austenitized and then is held at T1=700, and T2= 680 C (both in the pearlite region of TTT diagram), to get 100% pearlite. Select the proper answer The pearlite will form at the same time at T1 and T2. The pearlite will form at a longer time at T1 than T2. The pearlite will form at a shorter time at T1 than T2.

The pearlite will form at a shorter time at T1 than T2.

In the Transformations which involve nucleation and growth stages, select on that does not apply, The transformation rate reaches a maximum at a temperature between the equilibrium temperature and 0 kelvin The transformation rate goes to 0 at temperatures approaching 0 kelvin. The transformation rate is equal to 0 at the equilibrium temperature. The transformation rate increases monotonically with temperature.

The transformation rate increases monotonically with temperature.

Select the one which is NOT RIGHT. The two stages involved in the formation of particles of a new phase is solidification and coring. The two stages involved in the formation of particles of a new phase are nucleation and growth. The growth stage is simply the increase in size of the new phase particles. The nucleation process involves the formation of normally very small particles of the new phase(s), which are stable and capable of continued growth.

The two stages involved in the formation of particles of a new phase is solidification and coring.

Metals with high melting temperatures (The so called refractory metals such as Tungsten, Molybdenum, Niobium) react at a high rate with oxygen at high temperatures. Because; Their oxides protects their surface. Their oxides have high melting temperature. Their oxides are very thin. Their oxides have poor mechanical properties.

Their oxides have poor mechanical properties.

Select the true statement. Polymers have strong covalent bonds in their long chain (LCM) molecules. Therefore we usually think them as corrosion resistant, which is true, for long term applications. Water, can penetrate into the polymers because of open structure and open spaces between LCM, causing swelling and sometimes cracking of the polymers.

Water, can penetrate into the polymers because of open structure and open spaces between LCM, causing swelling and sometimes cracking of the polymers.

Select the true statement If photons of UV light have higher energy than the bond energy, then the chemical bonds in a polymer can be broken. This will cause the molecular mass to increase and the physical properties of the polymer to change. When UV light is absorbed in a polymer: Bonds between LCMs and along LCMs are broken, so degrades mechanical properties.

When UV light is absorbed in a polymer: Bonds between LCMs and along LCMs are broken, so degrades mechanical properties.

In the Zn-Cu Corrosion couple ( the so called Daniel Cell) select the true statement; Cu does the anodic reaction Zn does the cathodic reaction Zn does the anodic reaction

Zn does the anodic reaction

In the Zn-Cu Corrosion couple ( the so called Daniel Cell) select the true statement; Cu is oxidized to Cu ions Zn is reduced to Zn ions Zn is oxidized to Zn ions

Zn is oxidized to Zn ions

Which of the following metals should not be in electrical contact with a critical structure made of low carbon steel that is used in a sea water environment? Based on the standard potential table. Zn Al Cu Mg

cu

In an electrochemical reaction the electrolyte can be; liquid solid polymer All of the answers.

all answers

What alloying element you add for corrosion/oxidation resistant steels? Phosphorous Sulfur Chromium Nickel

chromium

Which one IS NOT a characteristics of "Free cutting Steel"? easily machinable small chip length durin cutting relatively soft cuts other materials freely

cuts other materials freely

Aluminum alloys can be strengthened by Martensitic phase transformation.

false

In semicoductors free electron and holes move at the same speeds ( drift velocities). (true or false)

false

Which one is not an outstanding property of Ultrahigh Molecular Weight Polyethylene (UHMWPE)? high impact strength resistance to wear/abrasion high coefficient of friction self-lubricating surface

high coefficient of friction

Which one is not characteristics of pure Aluminum; High ductility even at very low temperature Corrosion resistant in ambient atmosphere. High electrical and thermal conductivity High specific yield strength.

high specific yield strength

In intrinsic semiconductors, ni (the intrinsic carrier concentration), increases linearly with increasing temperature increases exponentially with increasing temperature decreases exponentially with increasing temperature Does not change with increasing temperature.

increases exponentially with increasing temperature

Small supercooling, select on that does not apply; causes few nuclei to be stable. leads to large crystals leads to small crystals leads to slow nucleation rate

leads to small crystals

Which one does not increase weathering of Polymers? low amounts of sunlight high amounts of sunlight high humidity Warm temperatures

low amounts of sunlight

In intrinsic semiconductors, ni is the intrinsic carrier concentration, n is the number of electrons in conduction band, and p is the number of holes in valence band, select the right answer ni=p=n ni>p=n ni=p>n

ni=p=n

Which one is not a property of Grey Cast Irons? not wear resistant excellent vibrational dampening graphites are flake shape weak & brittle in tension stronger in compression

not wear resistant

The bandgap is important to the optical properties of semiconductors because the process of absorbing light requires electrons to move from an occupied state to an unoccupied state. Light arrives in discrete bunches called photons with energies that are inversely proportional to their wavelengths. The energy E of a photon with wavelength Lamda is: E = h(c/Lamda) Here c is the speed of light, 300,000 km/s. h is Plank constant 6.62*10^-34 Js. Be careful with units! The most convenient units for E are electron volts, with 1 eV=1.6 * 10-19 J. For Ge, Eg = 0.67 eV. The visible spectrum range is 400-700 nm. What is the color of Ge? transparent colored opaque.

opaque

Precipitation hardening is another heat treatment process that improves the mechanical properties by solid state reactions which leads to precipitates to act as obstacle to dislocation motion, and thus makes the material stronger.

true