Please enable JavaScript.

Coggle requires JavaScript to display documents.

Scanning electron, Continuous improvement (CI), X -Ray diffraction, NDT…

- - - - lesser the interaction volume
  - - - we measure the interaction volume
  - - - gives topological profile
        
        shadow image
        
        easier for us to interpret??
    - - chemical contrast - figure out type of atoms :
        
        sensitive to type of atoms
        
        Higher energy , typically same as incident electrons
    - - computer solves the diffraction pattern to give the material > orientation of the pattern ( same color for similar orientation).
      - Orientation of crystallographic arrangement
      - can see the texture and cooling pattern maybe??
      - not in the paper
    - - Diffraction: nlamda = 2dsintheta
      - Detector principle
        
        WDS
        
        Mechanical callibration required
        
        rotation of crystals
        
        Resolution is good 5eV
        
        can't see the entire spectrum in one go (multiple arrangement required
        
        single channel analyzer
        
        radiation is reflected onto a crystal to the deflector
        
        therefore produce a lot of x-ray
        
        NOT FOR SENSITIVE SAMPLES
        
        way too sensitive than EDS
        
        Why required?
        
        Some overlaps cannot be detected by EDS becasue of poor resolution
        
        High resolution
        
        EDS
        
        INcoming x-rays
        
        Si-Li detector
        
        Si drift detector
        
        Advantage: Liquid nitrogen not required
        
        poor resolution
        
        possible to analyse a large sample area
        
        lighter elements are tough to measure
        
        Types of analysis
        
        Line - define a line over which we are measuring
        
        Area map
        
        Point
        
        Elemental Mapping
        
        Faster than WDS
        
        to have an overview
        
        Basic Principle: Bombard electrons>> Characteristics X-ray reading (Kalpha, Kbeta , Lalpha etc.)
        
        ENERGY is MEASURED
        
        Artefacts
        
        Peak broadening
        
        Silicon x-ray escape peak
        
        effect of tilitng
        
        the interaction volume is inside and we don't know the phase of it, could give a different element
        
        Don't be too close to a phase boundary
        
        can be due to a rough surface
        
        lower path length is advantageous
      - types of scanning- Point (most often), line analysis
    - - not in interest for us
- - - - Spherical abberation
        
        Focal point mismatch
        
        at the end o the lens, the bending is more
      - Diffraction
      - Chromatic abberation
        
        Energy focal point change??
    - - over focus
        
        elongation of a spherical particle
      - under-focus
- - - - H+k+l = even
    - - h+k+l = odd
  - - - leads to absence of supposedly peaks
- - - - difficult
- - - - Types of noises
        
        surface curvature and roughness
        
        noisiness of the microstructure
        
        probe size and focal properties
        
        Multifaceted flaws, scatters sound away from transducers
    - - High penetration depth
      - High sensitivity
      - High accuracy
      - rapid, can be installed on site
      - can handle complex geometry
      - density and material properties
    - - SIGNIFICANT operator training
      - proper contact is required
      - cannot detect planar faults perpendicular to wavefront
      - expensive
  - - - Visualization of defect
      - material density, thickness and other material measurements
      - Rapid area inspection
    - - Dangerous
      - Expensive
      - cannot detect closed cracks
      - sexy operator required
      - It is advisable to know the direction of the crack as cracks with minimal depth in the direction of radiation is really hard to identify.
        
        known flaw orientation is helpful
- - - - Specific characterization of material properties
    - - Flaw detection and Evaluation
      - Leak Detection
      - Stress/strain and dynamic parameter measurements
      - Dimensional Measurements
      - Estimation of mechanical and chemical properties
      - Leads to (Applications)
        
        Assisstms in the PLCM
        
        screen and sort incoming materials
      - Effects due to manufacturing
        
        Welding issues, hot/cold crack, lack of fusion
        
        Inclusions> Pores and slag
- - - - Cr plating defects
      - grinding based thermal defects
- - - - 1:3?
    - - balance time and resolution
      - dense object - higher flux of x-rays
      - x-ray dampening propeortional to atomic number ^3
      - we have a balance between noise contrast and resolution
- - - - shape and size can tell the fatigue growth direction
      - flatter ones are more brittle in nature
      - called craters or dimples
  - - - instantaneous (milliseconds??)
    - - Presence of tongues
        
        in welds?
      - Presence of cleavage steps
      - Presence of river marks
        
        twist and tilt of boundaries
  - - - the final load cycle which would lead to the final fracture ductile or brittle
    - - change in the amplitude of the fatigue load
      - different from the striations
        
        can only be seen in the SEM
        
        1 micrometer - limit??
      - crescent or parabolic in shape
      - shape is dependent on the remaining cross-section
    - - meeting point of two fatigue growths at different planes
      - even without beach marks, these particular marks can indicate
    - - intergranular where we have strong materials with weak grain boundaries
  - - - microvoid coalescence
- - - - surfaces touching each other due to loading conditions
      - crack closure
      - smearing of surfaces due to human contact.
        Moisture+salt?? Chemical too?
    - - stress corrosive cracking
      - Liquid metal embrittlement
      - corrosion fatigue
- - - - change in between gases to make different compounds to have different types of weight loss
      - Nitrogen is the default
      - 2 inlet could be air to bun carbon black
    - - Metals require higgher resolution becasue of loss is in the range of 0.4%
    - - First derivative of the TG curve
        
        It'll give peaks. These peaks indicate the decomposition temperature of the constituents
  - - - go for top loading thermo balance
    - - boyouncy effect if there's absence of vacuum
        
        loss of metal weight due to creation of vacuum
    - - seperation of layers of gasses which can lead to change in measurement of weight
      - advantage = lack of buoyancy effect
      - barely used - because of inaccuracy
  - - - low temperature - high sensitivity ; higher temperature - low sensitivity
      - choose type of thermocouple based on temperature application range and calibration requirement
    - - Gold izz da baast
        
        but will melt down at higher tempeature
      - ceramics is most efficient
      - for poly - aluminum does the trick
      - use compatibiltiy charts
    - - Transformation enthaplies
      - phase transitions
      - make phase diagrams
  - - - Very high sensitivity
      - Surface contact doesn't matter much like in DSC
      - sensitivity is not dependent on test geometry
    - - figure out the decomposition
  - - - Horizontal
        
        Easy Handling
        
        High Temp range
      - Vertical
        
        Tension and compression possible
        
        High load range
    - - Linear Thermal expansion
      - coefficient of expansion
      - Softening points
      - Shrinkage steps
- - - - charge compensation from unnecesary electron evasion from Ar and other gas maybe/
- - - - Using Ar+ etching
- - - - Solution is to adjust the control factors at the supplier end
- - - - contrast
      - can give an idea of surface roughness, more roughness = less secondary electron emission received
    - - absorbs and releases low energy electrons
  - - - Higher atomic number element will reflect higher electrons shine brighter