ChE 361 #3
What limits the pressure at which a bearing material can operate?
What limits the sliding velocity at which a bearing material can operate?
What is an asperity?
What is the usual cause of failure of rolling bearings?
What is the process by which fragments are torn from a surface where work-hardened junctions stick together?
What is the process in which hard asperities or embedded hard particles plough through a softer material?
Name four surface treatments that increase hardness or reduce friction?
Ceramic deposition by plasma
What is hydrodynamic lubrication?
Lub by full viscous film between two surfaces
What are the fixed points on the kelvin temperature scale?
Triple point of water
What is the triple point of water?
What is the ice point of water?
Conversion from F to C?
What is the SI unit of heat?
What is the SI unit of work?
What is the SI unit of power?
Conversion from Calories to calories?
Conversion from calories to Joules?
What is boundary lubrication?
Chemisorbed monolayers of polar molecules
Why is the negative sign required in the equation q=-(lambda)dT/dx?
Heat flows from high to low temperature
What is alpha in the equation alpha=(1/L)(dL/dT)?
Linear thermal expansion coefficient
Why is the negative sign included in the equation J=-D(dc/dx)?
Diffusion occurs from high concentrations to low concentrations
What is Q in the equation D=D
Why is the negative sign in the equation D=D
Increasing activation energy decreases the diffusion coefficient
What are the SI units of diffusive flux?
What are the SI units of concentration?
What are the SI units of the concentration gradient?
Where does interstitial diffusion occur?
In spaces between atoms in crystals
What causes creep fracture?
Creation and growth of internal cavities
During which stage does creep damage accumulate?
Definition of yielding by dislocation plasticity?
Dislocations glide in response to shear stress
Definition of plastic deformation?
Bonds stretch but do not break
Definition of power-law creep?
Dislocations glide and climb over obstacles
Definition of diffusional flow?
Diffusion extends grains in direction of stress
What occurs when T=T
Phase change occurs
What is climb?
Dislocation movement out of glide plane
What is the mechanism by which climb occurs?
Diffusion of atoms away from a dislocation
What results from the presence of an extra half-plane of atoms in a crystal?
What tends to promote creep in a metal or ceramic?
What tends to promote creep in a polymer?
What is creep relaxation in a pre-tensioned component such as bolt?
Stress reduction by creep
Which materials tend to creep the most at room temperature?
ChE 361 #3
Engineering materials final