Unannounced Quiz Flashcards
You are assigned to a team responsible for designing a new medical device. A portion of the technical endpoints for this device requires it must be made of a material that is nonconducting and isotropic. You are in charge of the materials engineering subgroup and must begin narrowing the field of candidate materials. You begin by excluding materials which have properties contrary to the endpoints. Materials you must exclude are those that are:
van der Waals bonded
James Bonded
ionic bonded
metallic bonded
covalently bonded
hydrogen bonded
metallic bonded
You rule out metallic bonds to eliminate conducting materials, but also must include isotropic materials. What other types of materials may need to be excluded to achieve this endpoint?
van der Waals bonded
hydrogen bonded
covalently bonded
ionic bonded
metallic bonded
covalently bonded
You decide to use a ceramic material for the new medical device. Information obtained from your search of the engineering literature suggests the best candidate material is crystalline. You then decide that qualification of this candidate crystalline material for device use requires determination of crystal structure. What technique(s) might you use to determine the crystalline structure of this material?
electron microscopy
X-ray diffraction
transmission electron microscopy
accurate digital micrometers to measure crystal unit cell dimensions
ultraviolet light diffraction
light microscopy
scanning electron microscopy
Infra-red spectroscopy
gamma-ray diffraction
X-ray diffraction
transmission electron microscopy
You perform X-ray diffraction analysis on the candidate ceramic material . The results obtained from the analysis are unexpected - no clear diffraction pattern is observed. You boss politely, but firmly, chides you for wasting company time and funds performing X-ray diffraction analysis on this material. You reply firmly, but professionally, that time and funds were not wasted because you note that: 1) in general absence of evidence is not evidence of absence and 2) information was obtained from the X-ray diffraction study. What information were you referring to?
the material is metallic
the material is not isotropic as originally believed
the material is not a non conductor as originally believed
the material is not a primitive unit cell
the material is not a ceramic after all
the material is not suitable for use as an implant
the material is not a primitive unit cell
Subsequent investigations of the candidate crystalline ceramic material reveal that the layers in the atomic structure are packed AB, AB, AB, AB, etc. You deduce that this crystal structure may therefore be:
IRS
NBC
CBS
FCC
Miller structure
FDA
HCP
KFC
HCP
Now that you related the AB, AB, AB… packing order to a HCP crystalline material, you also know that the medical device you are responsible for helping create will be surgically implanted and incorporated in some portion of the human musculoskeletal system. Your next logical course of action might be to gain additional information about the (fill in the blank) properties of this material.
thermal
rheological
nuclear
optical
electrical
mechanical
mechanical
Given the HCP structure of this candidate ceramic material you recognize that this information has mechanical property implications. What specifically might these implications include?
nuclear reactor neutron containment material
tough
electrical insulator
strong
thermal insulator
not tough
not strong
not tough
You prepare a report to engineering management that the candidate implant materials is a crystalline ceramic with HCP structure and is likely not tough. You supervisor challenges your supposition and asks you to defend it. The information you provide supportive of the “not tough” conclusion is obtained from the (fill in the blank)
unit cell structure
absence of Schottky defects
presence of voids
few close packed planes in the unit cell structure
many close packed planes in the unit cell structure
absence of Frenkel defects
presence of Schottky defects
presence of Frenkel defects
few close packed planes in the unit cell structure
Due to the brittle nature of the candidate ceramic material, you supervisor indicates that the mechanical properties should be toughened and proposes solution hardening of this material by adding element X. You are then requested to design an experiment to determine if it is possible to add element X to this ceramic material. You reply that a study is unnecessary for a preliminary estimate of the (fill in the blank) of element X in this ceramic.
utility
hardenability
futility
conduction ability
permeability
solubility
toughening ability
solubility
Your supervisor replies “well done, this will save the organization time and funds, but how will you determine if element X is soluble in the candidate ceramic material?” You respond that you will use the ( fill in the blank).
Hall-Petch relationship
Miller indices showing [100] plane spacing
Hume-Rothery Rules
Heisenberg Principle
Fick equations
Bragg lattice spacing requirement
Clausius-Clapeyron relationship
Bragg law
Hume-Rothery Rules
Your supervisor is impressed that you employed a useful materials engineering tool (the Hume-Rothery rules) to theoretically estimate the solubility of element X in the candidate ceramic material. One of the these rules specifically addressing your supervisor’s concern is that element X must not have more than a (fill in the blank) incompatibility regarding the (fill in the blank).
10%, valence
20%, valence
15%, valence
10%, atomic radius
15%, electronegativity
20%, valence
15%, atomic radius
15%, crystal structure
15%, atomic radius
You consult a handbook and find a table of atomic radii and note that element X has an atomic radius about 22% larger than the radii of the constituent ceramic atoms. This means that the solubility of element X in the candidate ceramic will be suboptimal and may introduce some degree of lattice strain in the structure which may in turn lead to dislocations in the material. The engineering metric quantifying the induced dislocations is the (fill in the blank).
size change of material pre & post element X addition
caterpillar movement dimension
yield point
interplanar spacing
melting point
hardness
unit cell volume change
crystal unit cell dimensions
burger’s vector
burger’s vector
Your supervisor is concerned that the magnitude of element X’s “misfit” in the crystal structure and size of resulting dislocations, quantified using burger’s vector, may introduce undesirable mechanical property alterations. You reply “quite the opposite, carefully controlled addition of element X and the subsequent creation of lattice strain and introduction of dislocations may actually introduce desirable properties.” Assuming careful control of a limited amount of element X into the material, what “desirable” property was in your mind when you made this comment?
decreased brittleness
decreased strength (material was too strong - incompatible with the host tissue)
increased modulus
increased strength
increased maximum load to failure
increased stiffness
decreased brittleness
Your supervisor is impressed with your materials engineering skills so far, and presses the issue by asking you to provide an explanation why the addition of element X, which is a “misfit” in the crystal structure of the candidate ceramic material and which introduces dislocations, can actually be beneficial. You inform your supervisor that the mechanism of this potential benefit could be the (fill in the blank) of atomic planes associated with these dislocations provided the number of dislocations is not (fill in the blank).
locking, small
slip, large
slip, contraindicated
slip, small
locking, large
locking, excessive
slip, large
You continue to provide sound materials engineering responses to your supervisor and have saved the organization considerable time and funding. Your supervisor is intrigued by your last response but then inquires “how do you know that your reasoning, however logical and sound it seems, is correct and applicable to this particular ceramic material with element X added”? You respond that the only way to know for certain is to (fill in the blank) the material.
microscopically examine
spectroscopically image (Fourier Transform Infrared Spectroscopy)
radiologically (X-ray) inspect
mechanically test
mechanically analyze
mechanically test
