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Characterization Flashcards

1
Q

If you are given the percentage of theoretical density? How do you find the porosity?

A

What’s not TD is porosity so its the other percentage to get 100

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2
Q

What is % total porosity?

A

open + close

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3
Q

(extra) If you have to choose to use the 3-point or 4-point bending test, which one?

A

4-point because of the positions of the stresses

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4
Q

What are the 7 different types of particle size distribution measuring techniques?

A

MSSCPRL
Mari says Sarina cries pretty rarely lately

Microscopy
Sieving
Sedimentation
Centrifugation
Permeation
Resistive Pulse
Light scattering

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5
Q

What can particle size distribution be used for?

A
  1. primary particle size
  2. agglomeration/aggregation degree of powder mixture
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6
Q

What is X-Ray diffraction?

A

The powder diffraction method used to identify the phases present & types of crystals in a material

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7
Q

What condition do X-Ray Diffraction beams have to satisfy? Why?

A

Bragg’s Law/condition

Because materials/powders are composed of numerous randomly oriented grains, the diffracted beams are produced from all crystalline planes that satisfy the law

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8
Q

What is Bragg’s Law?

A
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9
Q

How do incoming X-rays interact with crystal planes?

A

they diffract from crystal planes

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10
Q

How do you compute the planar spacing, d with X-ray diffraction?

A
  1. measure the critical angle
  2. plug into the formula
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11
Q

What is intensity measured as a function of in X-Ray diffraction?

A

of angle theta

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12
Q

In XRD, what do the angles where a peak in intensity occurs correspond to?

A

a unique set of crystalline planes

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13
Q

What is a result of X-Ray diffraction and how is it compared?

A

A unique set of angle values results, which are compared to the known angle values from material standards

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14
Q

What would the XRD pattern look like of a crystalline vs. amorphous material?

A
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15
Q

What does SEM stand for?

A

scanning electron microscopy

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16
Q

How does SEM work?

A

an electron beam is shot at the specimen then different signals come out of it from electron scattering

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17
Q

What do SEM results look like?

A
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18
Q

What are two dif types of TEM?

A

Bright field imaging and off-axis dark field

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19
Q

What kind of samples does TEM require?

A

Very thin ones

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20
Q

What do TEM results look like?

A
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21
Q

What are two ways to measure density? What are they good for? What are their characteristics?

A

Gas Pycnometry and Archimedes’ method

Gas:
- for powders
- based on Boyle’s law

Archimedes’
- for pieces
- % of theoretical density
- allow to calculate porosity
- ASTM method

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22
Q

What are the four different types of densities? What are their subscripts?

A
  1. theoretical, th
  2. true, tr
  3. apparent, a
  4. bulk, b
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23
Q

What is theoretical density?

A

based on crystal structure, the volume of the unit cell and the number and atomic weights of the ions in the volume

24
Q

How would you measure theoretical density?

25
What is true density?
include the effects of defects and grain boundaries
26
How is true density measured?
pycnometry
27
What is apparent density?
Includes only the closed pores, defects, and grain boundaries
28
What test/s measure apparent density?
combo of pycnometry and archimedes' principle
29
What is bulk density?
includes all pores (open and closed) as well as defects and grain boundaries
30
How do you measure bulk density?
Archimedes' principle, and for simple shapes it can measured external dimensions and weight
31
What types of measured densities are the greatest?
32
What are the differences of the different types of densities?
Theoretical: perfect example True: defects & grain boundaries Apparent: closed pores, defects, & grain boundaries Bulk: all pores (open and closed), defects, and grain boundaries
33
How do you calculate theoretical density?
mass of unit cell/ volume of unit cell
34
What is the theoretical density based on?
crystal structure, volume of the unit cell and the number and atomic weights of the ions in the volume of
35
How do you calculate true density?
36
What are the common variables that we use in density calculations?
37
How do you calculate apparent density?
38
How do you calculate bulk density?
39
What is Wd? Ws? Wss? pl?
WD = dry weight of sample Ws = saturated weight of sample Wss = saturated‐suspended weight of sample ρl = typically the density of water, 1 g/cm 3
40
What are DTA-TG used for? Better for? When do you use it?
1. used for powders or pieces 2. better for green bodies to follow up and design the calcination and pyrolysis 3. Follow up removal of organic additives
41
How do you calculate volume of open porosity? percent?
so basically the saturated sample weight - dry sample weight divided by the density of water percent open pores-> V op/ V bulk
42
How do you calculate the volume of closed porosity? % closed pores?
V cp = V apparent (no open pores) - V true (no pores) percent closed = Vcp/V bulk
43
How do you calculate the total porosity? % total pores?
V total = V bulk - V true (no pores) % total pores = V total / V bulk
44
What do you use a Dilatometer for?
1. used to design sintering cycles 2. Tracking shrinkage @ dif temps
45
What are three different types of mechanical tests?
1. 3-point and 4-point bending 2. Indentation 3. Axial compression
46
What are three important thermal properties?
1.Thermal conductivity/thermal diffusivity 2. Thermal expansion coefficient 3. Thermal shock
47
What are tests to find thermal conductivity/ thermal diffusivity?
1. laser flash 2. transient plane source (TPS) method
48
What test do you use to find thermal expansion coefficient?
Dilatometer (shrinkage w temp)
49
How do you find thermal shock?
Thermal cycling or localized heating coupled with mechanical testing and microscopy
50
What are three important electrical properties?
1. electrical resistivity 2. electrochemical impedance spectroscopy EIS 3. seebeck coefficient
51
What are different ways you could measure electrical resistivity?
1. 2 or 4 probe measurement 2. 4 point probe measurement 3. pulse probe 4. disc or pellet method 5. non-contact electrical resistivity
52
What are 2 benefits of characterization techniques?
1. Allow to obtain information of each step in ceramic processing 2. Allow for better design of the steps in ceramic processing and to perform quality control of the ceramic products
53
What is necessary to understand the properties of a sample or material?
The results of the different and complementary processing techniques
54
What is key to obtaining the maximum and most reliable information from each technique?
Sample preparation
55
What do the angles where the peak in intensity occurs in X-Ray diffraction correspond to?
A unique set of crystalline planes

Advanced Ceramics (10 decks)

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