MAE 183A Midterm 1

Primary bonds are:

metallic, ionic, covalent

What type of atomic bonding characterizes the ceramics?

Covalent and ionic bonding

How are a polymer's properties affected when it takes on a crystalline structure?

Density, stiffness, and melting temperature increase.

Which one of the following is the most common element in the earth's crust

Oxygen

Which of the following are examples of generating the workpart geometry in machining, as opposed to forming the geometry (two best answers):

contour turning, profile milling

What are the three basic categories of polymers

(1) thermoplastics, (2) thermosetting polymers, and (3) elastomers.

Describe the melting characteristics of a noncrystalline material such as glass

. In the heating of a noncrystalline material such as glass, the material begins to soften as temperature increases, finally converting to a liquid at a temperature defined for these materials as the melting point

In a turning operation, the change in diameter of the workpart is equal to which one of the following

2x depth of cut

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 polymer

A compound comprised of long-chain molecules that consist of repeating units, called mers, connected end to end.

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 an alloy

A mixture of two or more elements, at least one that is metallic

Tensile testing is not appropriate for hard brittle materials such as ceramics. What is the test commonly used to determine the strength properties of such materials

A three-point bending test is commonly used to test the strength of brittle materials. The test provides a measure called the transverse rupture strength for these materials

What is an electrolyte?

An electrolyte is an ionized solution capable of conducting electric current by movement of the ions.

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

Which one of the following engineering materials is defined as a compound containing metallic and nonmetallic elements

Ceramic

What is the difference between consumer goods and a capital goods? Give some examples in each category

Consumer goods are products purchased directly by consumers, such as cars, personal computers, TVs, tires, and tennis rackets. Capital goods are those purchased by companies to produce goods and/or provide services.

Polymers are characterized by which two of the following bonding types:

Covalent, van der waals

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

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.

Copper is generally considered easy to weld because of its high thermal conductivity (T or F)

False

The coefficient of thermal expansion measures the change in volume of a material per degree of temperature (T or F)

False. The coefficient of thermal expansion measures the change in length, not volume, per degree of temperature.

Distinguish between generating and forming when machining part geometries.

Generating refers to creating part geometry using the feed trajectory of the cutting tool; examples include straight turning, taper turning, and profile milling. Forming involves creating part geometry using the shape of the cutting tool; common examples include form turning and drilling.

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

How do grain boundaries contribute to the strain hardening phenomenon in metals

Grain boundaries block the continued movement of dislocations in the metal during straining. As more dislocations become blocked, the metal becomes more difficult to deform; in effect it becomes stronger

Which of the following bond types are classified as secondary bonds

H- bonding, van der waals, dipole dipole

Describe the melting characteristics of a noncrystalline material such as glass

In the heating of a noncrystalline material such as glass, the material begins to soften as temperature increases, finally converting to a liquid at a temperature defined for these materials as the melting point

What are the four most common elements in the earth's crust

Oxygen, silicon, aluminum, and iron

What is the difference between primary and secondary bonding in the structure of materials?

Primary - between atoms, Secondary - between mcls

Mining is classified in which one of the following industry categories

Primary industry

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 is the main advantage of having "slip" for manufacturing?

Slip causes materials to be more ductile and therefore easier to shape

Define specific heat as a material property.

Specific heat is defined as the quantity of heat required to raise the temperature of a unit mass of the material by one degree

Define steel

Steel can be defined as an iron-carbon alloy containing 0.02% to 2.11% carbon

The copper-nickel system is a simple alloy system, as indicated by its phase diagram. Why is it so simple

The Cu-Ni alloy system is simple because it is a solid solution alloy throughout its entire composition range

What is the range of carbon percentages that defines an iron-carbon alloy as a steel

The carbon content ranges from 0.02% to 2.11%.

Define the recrystallization temperature for a metal

The recrystallization temperature is the temperature at which a metal recrystallizes (forms new grains) rather than work hardens when deformed

What is so special about the superalloys? What distinguishes them from other alloys

The superalloys are generally distinguished by their strength and resistance to corrosion and oxidation at elevated temperatures.

Define yield strength of a material

The yield strength is the stress at which the material begins to plastically deform. It is usually measured as the 0.2% offset value,

Explain why aluminum, magnesium, and titanium are expensive when they are abundant on earth. Give a reason to recycle aluminum

They require tremendous amount of electricity for extraction from their natural state. Recycling aluminum saves energy and reduces the cost of aluminum

What is the difference between threading and tapping?

Threading is on shaft, tapping is in holes

If engineering stress and true stress were measured simultaneously during a tensile test, which would have the higher value

True stress > eng stress

Under what circumstances does the strength coefficient have the same value as the yield strength?

When the material is perfectly plastic and does not strain harden

What is work hardening

Work hardening, also called strain hardening, is the increase in strength that occurs in metals when they are strained.

A lathe can be used to perform which of the following machining operations (three correct answers):

boring, drilling, turning

Which one of the following engineering materials is defined as a compound containing metallic and nonmetallic elements

ceramic

Which of the following alloying elements are most commonly associated with stainless steel (two best answers

chromium, nickel.

Deformation processes include which of the following (two correct answers)

extrusion, forging

Choose one answer that describes "glass ceramic" the best

glass material that is mostly crystalline

Name three most typical precious metal

gold, silver, platinum

Which of the following operations are classified as material removal processes (three correct answers):

grinding, milling, turning

In some composite materials, a third ingredient is added to promote bonding of the primary and secondary phases. This third ingredient is called which one of the following

interphase

Which of the following are point defects in a crystal lattice structure

interstitialcy, Schottky defect, vacancy

Which one of the following metals has the lowest density: (a) aluminum, (b) copper, (c) iron, (d) magnesium, or (e) tin?

magnesium

Which one of the following types of stress strain relationship best describes the behavior of brittle materials such as ceramics and thermosetting plastics

perfectly elastic

The iron tapped from the blast furnace is which one of the following

pig iron

In an electrolytic cell, the anode is the electrode that is

positive

Glass products are based primarily on which one of the following minerals

silica

1: Which one of the following is the correct definition of ultimate tensile strength, as derived from the results of a tensile test on a metal specimen:

the maximum load divided by the original area of the specimen

Which one of the three polymer types does not involve cross-linking

thermoplastics

Boring and reaming share the common feature that they are both used to enlarge an existing hole:

true

Curing of elastomers is known as which one of the following terms

vulcanization

Identify the four types of permanent joining processes used in assembly.

welding, brazing, soldering, and adhesive bonding

Galvanized steel is steel that has been coated with which one of the following metals

zinc