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Metal Casting Technologies : March 2008
44 TECHNICAL FEATURE www.metals.rala.com.au A New Electron Probe Microanalysis Facility at MTEC The Trace Element Analysis Laboratory (TEA-Lab) at the National Metal and Materials Technology Center (MTEC) of Thailand has recently installed a Shimadzu Electron Probe Microanalyser, model EPMA-1610. This new instrument is fitted with both a tungsten filament and a CeBix cathode as emission electron guns, and can achieve a maximum magnification of 200,000X with a best resolution of 5 nm at 30 kV. Use of a CeBix cathode as an emission electron gun enables higher brightness from smaller beam currents resulting in better spatial resolutions as well as longer operating life. The high take-off angle (52.5°) in the instrument allows the analysis of specimens with uneven surfaces. The EPMA-1610 is equipped with a Super backscattered electron (BSE) detector, ET secondary electron (SE) detector, cathodoluminescense (CL) detector, plus wavelength and energy dispersive spectrometers (WDS and EDS). Various programs are available for analysis, e.g., qualitative, semi-quantitative and fully quantitative analysis, mapping analysis, image analysis and thin film analysis. The WD spectrometer is fitted with a range of diffracting crystal types (LIF, PET, RAP, ADP, PbST, LSA70 and LSA200) allowing analysis of all elements from Be4 to U92. All the instrument operations and data processing are controlled via mouse command on the host computer work station. Maximum specimen size is 100 mm square by 50mm. A multi-specimen rotation stage can be fitted to enable up to six 25mm diameter samples to be loaded together. Examples of the information that can be obtained from the EPMA include elemental composition, the valency and chemical-bonding state of compounds, mapping for trace quantities of elements in materials, and analysis of sensitive specimens such as polymeric materials and biological specimens without damage. As well as providing an analysis service for Thai industry and university researchers, the head of the TEA-Lab, Dr. Aree Thanaboonsombut is also conducted research on materials such as electro-ceramics for the electronics sector and on problems due to trace elements. MTEC investigator Khun Narueporn Vaneesorn putting the new EPMA through its paces