Exam I questions - 2019 spring

What is the difference between a live center and a dead center, when these terms are used in the context of workholding in a lathe?

A center holds the workpiece at the tailstock end of the lathe. A live center is mounted in bearings and rotates with the work. A dead center does not rotate - the work rotates about it

What is a plasticizer?

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

Define steel

An iron-carbon alloy containing 0.02% to 2.11% carbon

Which one of the following elements is the most important alloying ingredient in steel: carbon, chromium, nickel, molybdenum, vanadium

CARBON

Is copper considered easy or difficult to weld? Why?

Difficult - high thermal conductivity makes the heat flow away from the joint rather than being concentrated to permit melting of the metal

T/F: The plastic region of the stress-strain curve for a metal is characterized by a proportional relationship between stress and strain

False

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

What is graphene?

Graphene is a one-atom-thick planar sheet of carbon

What is the primary mineral in glass products?

Silica, or silicon dioxide (SiO2).

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

Superalloys are generally distinguished by their strength and resistance to corrosion and oxidation at ELEVATED TEMPERATURES

Cross-linking (curing) of the various thermosetting plastics is accomplished by one of several ways. Name two

all answers: temperature activated systems, catalyst activated systems, mixing-activated systems, ultraviolet light activated systems

what is a flow curve

an equation that provides a good approximation of behavior of metals in plastic region, including their capactiy for strain hardening

When the drill bit in a drilling operation does not exit the opposite side of the work, the resulting hole is called which one of the following: blind hole or a through hole

blind hole

Which of the following processes start with a material that is in a fluid or semifluid state and solidifies the material in a cavity: casting, forging, machining, molding, pressing, and turning

casting and molding

ceramics are characterized by which of two of the following bonding types: adhesives, covalent, hydrogen, ionic, metallic, and van der Waals

covalent, ionic

Typical operations performed on a machining center include which of the following answers: boring drilling milling sawing and turning

drilling and milling

Properties and characteristics of glass-ceramics include which of the following (two best answers): efficiency in processing, electrical conductor, high thermal expansion, and strong, relative to other glasses

efficiency in processing, strong relative to other glasses

Which one of the following types of stress strain relationships best describes the behavior of most metals at room temperature: elastic and perfectly plastic, elastic and straing hardening, perfectly elastic, or none of the above?

elastic and strain hardening

T/F: A ceramic material can be defined as a microscopic physical mixture consisting of a metal or semimetal and one or more nonmetals

false - not a physical mixture but a COMPOUND

T/F: The coefficient of thermal expansion measures the change in cross section area of a material per degree of temperature

false, measures change in length per degree of temperature

T/F: As the degree of crystallinity in a given polymer increases, the polymer becomes denser and stiffer, and its melting temperature decreases

false; melting temperature increases

If engineering stress and true stress were measured simultaneously during a tensile test, true stress would be higher or lower than engineering stress?

higher

The strength and hardness of steel increases as carbon content increases or decreases?

increases

Which of the following are point defects in a crystal lattice structure (two correct answers): edge dislocation, grain boundaries, interstitialcy, screw dislocation, or vacancy?

interstitialcy

In a tensile test, true strain is greater/less than engineering strain

less than

In the cooling of most molten metal alloys, solidification begins at a certain temperature and concludes at a lower temperature. In these cases, which of the following temperature marks the beginning of solidification: liquidus or solidus?

liquidus (BEGINNING OF SOLIDIFICATION so it's going to the liquid limit)

In a battery (i.e. as opposed to the eletrolytic cell commonly used for manufacturing processes), the anode is the electrode that is positive or negative?

negative

Inventions of the Industrial Revolution include which one of the following: automobile, cannon, printing press, steam engine or sword

steam engine

Which figure shows the characteristic grain structure in a casting of a pure metal

upside down Y with no intermediate region

curing of elastomers is known as which one of the following term: crystallization, firing, reinforcing, sintering, or vulcanization

vulcanization

Galvanized steel is steel that has been coated with which metal

zinc