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SEM Techniques

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Computer-Controlled Scanning Electron Microscopy (CCSEM)

CCSEM is an automated SEM technique that determines quantity, particle size, and chemistry ideally for particles 1 µm to 100 µm in size (has been modified to include particles 1 to 300 µm). CCSEM is used for coal, coal ash, biomass, and biomass ash. Because the technique can be used on both fuel and ash, direct comparisons can be made and inorganic transformations inferred.

SEM Point Count (SEMPC)

SEMPC is an automated SEM technique that determines bulk chemistry and can be used to determine silicate viscosity distribution. It is used for deposits, coal ash, and biomass ash.

Morphology

Morphology is a manual SEM technique to examine material for visual appearance (surveying), spot and/or area chemical analysis, spatial arrangement of chemical phases, crystallography, line scans, and mapping of distribution or particular elements.

WETSEM

WETSEM is a technique for examining and/or analyzing wet samples in the SEM. Any type of nonhazardous wet sample is placed in the specially designed capsules, and the material is analyzed/examined using the SEM.

EBSD

EBSD is a technique which allows crystallographic information to be obtained from samples in the SEM. A stationary electron beam strikes a tilted crystalline sample, and the diffracted electrons form a pattern on a fluorescent screen. Just as in powder x-ray diffraction, these patterns are characteristic of the crystal structure and orientation of the sample region from which they were generated. Computer software then compares these patterns to a known database and thus identifies, or indexes, the crystalline phase. Maps can be produced that include information such as crystal phases, crystal orientation, and residual stress.