Electron Probe Micro Analyser

This technique utilizes a highly focussed electron beam (5-30 keV) to probe the elemental composition of the sample. The electrons in the beam interact with the sample over a very minute area and excite the elements present there to produce their characteristic x-rays. These characteristic x-rays are recorded and the elements present in the sample can be identified using a Wavelength Dispersive XRF spectrometer (WDF). Both qualitative and quantitative analysis is possible with this non-destructive method, with ppm detection level and 1% reproducibility. 

Using suitable detector, the following image analysis can be done  

Analysis of the images occurred from the secondary electrons (SEI), backscattered electrons (BSE) and cathode luminescence (CL). 

Using EDS and WDS, compositional information data collection is possible. 

Analysis of crystal lattice preferred orientation (EBSD) is possible. 

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A scratch was created on the coated specimen using a rod with a diamond tip on a scratch tester (IMC-1552, Imoto Machinery Co. Ltd.). The load for the scratch was 30 g. The scratched specimen was put in a holder and connected to a conductive wire, followed by immersion in a 0.0005 M NaCl corrosive solution, maintained at 40°C. The electrochemical impedance spectroseopy of the scratched specimen was measured at intervals of 4 h, or more, for a total of 24 h. Measurement data were analysed to calculate the polarisation resistance after the test. Scratched specimens were also immersed in a 0.0005 M NaCl corrosive solution at 40°C for 7 days. The surface appearance of the specimens was observed after the corrosion test to confirm the self-healing properties of the coatings. The seratched part of the specimen was analysed after the corrosion test by Electron Probe Micro-Analysis (EPMA). 

Electron beams can be used for the probe which can analyze the micro portions of the sample s surface, ranging from nanometer to micrometer scales, because the electron beams can be easily narrowed by using the magnetic field. The infiltrated depth of the electron beams is usually smaller than that of the X-rays, suggesting that the electron beam analyses should be one of the best methods for surface analyses. 

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