Characterization Flashcards
If you are given the percentage of theoretical density? How do you find the porosity?
What’s not TD is porosity so its the other percentage to get 100
What is % total porosity?
open + close
(extra) If you have to choose to use the 3-point or 4-point bending test, which one?
4-point because of the positions of the stresses
When an incident beam is shined at a sample, what are the three types of electrons that go through the sample? What do you learn from them?
- Elastically scattered electrons
- structural analysis & HR imaging
- Transmitted electrons
- morphological info
- Inelastically scattered electrons
- composition and bond states
When an incident beam is shined at a sample, what are the 5 types of electrons/matter that are “reflected”?
- angular electrons
- x-rays
- primary backscattered electrons
- cathodoluminescence
- secondary electrons
What are the 7 different types of particle size distribution measuring techniques?
MSSCPRL
Mari says Sarina cries pretty rarely lately
Microscopy
Sieving
Sedimentation
Centrifugation
Permeation
Resistive Pulse
Light scattering
What is X-Ray diffraction?
The powder diffraction method used to identify the phases present & types of crystals in a material
What condition do X-Ray Diffraction beams have to satisfy? Why?
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
What is Bragg’s Law?
How do incoming X-rays interact with crystal planes?
they diffract from crystal planes
How do you compute the planar spacing, d with X-ray diffraction?
- measure the critical angle
- plug into the formula
What is intensity measured as a function of in X-Ray diffraction?
of angle theta
What do the angles where the peak in intensity occurs in X-Ray diffraction correspond to?
A unique set of crystalline planes
What is a result of X-Ray diffraction and how is it compared?
A unique set of theta values results, which are compared to the known theta values from material standards
What would the XRD pattern look like of a crystalline vs. amorphous material?
What are two dif types of TEM?
Bright field imaging and off-axis dark field
What kind of samples does TEM require?
Very thin ones
What are two ways to measure density? What are they good for? What are their characteristics?
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
What are the four different types of densities? What are their subscripts?
- theoretical, th
- true, tr
- apparent, a
- bulk, b
What is theoretical density?
based on crystal structure, the volume of the unit cell and the number and atomic weights of the ions in the volume
How would you measure theoretical density?
XRD
What is true density?
include the effects of defects and grain boundaries
How is true density measured?
pycnometry
What is apparent density?
Includes only the closed pores, defects, and grain boundaries
What test/s measure apparent density?
combo of pycnometry and archimedes’ principle
What is bulk density?
includes all pores (open and closed) as well as defects and grain boundaries
How do you measure bulk density?
Archimedes’ principle, and for simple shapes it can measured external dimensions and weight
What types of measured densities are the greatest?
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
How do you calculate theoretical density?
mass of unit cell/ volume of unit cell
How do you calculate true density?
How do you calculate apparent density?
How do you calculate bulk density?
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
What are DTA-TG used for? Better for? When do you use it?
- used for powders or pieces
- better for green bodies to follow up and design the calcination and pyrolysis
- Follow up removal of organic additives
What do you use a Dilatometer for?
- used to design sintering cycles
- Tracking shrinkage @ dif temps
What are three different types of mechanical tests?
- 3-point and 4-point bending
- Indentation
- Axial compression
What are three important thermal properties?
1.Thermal conductivity/thermal diffusivity
2. Thermal expansion coefficient
3. Thermal shock
What are tests to find thermal conductivity/ thermal diffusivity?
- laser flash
- transient plane source (TPS) method
What test do you use to find thermal expansion coefficient?
Dilatometer
How do you find thermal shock?
Thermal cycling or localized heating coupled with mechanical testing and microscopy
What are three important electrical properties?
- electrical resistivity
- electrochemical impedance spectroscopy EIS
- seebeck coefficient
What are different ways you could measure electrical resistivity?
- 2 or 4 probe measurement
- 4 point probe measurement
- pulse probe
- disc or pellet method
- non-contact electrical resistivity
What are 2 benefits of characterization techniques?
- Allow to obtain information of each step in ceramic processing
- Allow for better design of the steps in ceramic processing and to perform quality control of the ceramic products
What is necessary to understand the properties of a sample or material?
The results of the different and complementary processing techniques
What is key to obtaining the maximum and most reliable information from each technique?
Sample preparation
