布鲁克 , EDS, 能谱仪, SEM, TEM

Portland cement is one of the basic materials in the construction industry. The principal component of Portland cement is clinker. According to the cement nomenclature, clinker contains two silicate phases: Ca3SiO5 (alite) and Ca2SiO4 (belite), as well as aluminate and ferrite. The alite to belite ratio is responsible for the strength of Portland cement in cement clinker. The ability of determining this ratio already during the burning phase is essential for the evaluation of the cement’s final strength.

Silicon drift detector (SDD) systems have become state of the art technology in the field of EDS (X-ray microanalysis). One of the main advantages of XFlash® SDDs is the extremely high pulse load capacity of up to 750,000 counts per second combined with good energy resolution (<123 eV Mn-Kα, 47 eV C-K at 100,000 cps). These two factors and modern data processing allow spectrum imaging where an entire EDS spectrum at each pixel of the SEM image is collected in a database termed “HyperMap”. This approach allows data evaluation with advanced analysis options, such as the Maximum Pixel Spectrum (Bright & Newbury 2004, Application Note # EDS-04) for improved element identification and spectroscopic phase analysis called “Autophase” (Application Note # EDS-03) for evaluating the composition and area fraction of major and minor components.

Commercially available high speed steel was analyzed simultaneously using the EBSD and EDS techniques at a very high speed of more than 200 points/s. Thanks to its extremely fast reanalysis option the CrystAlign™ software permits the user to launch measurements without knowing all the phases present in the sample. This in turn significantly reduces the preparation time needed before launching the measurement. Thanks to these new hardware and software developments the SEM occupation time for acquiring a map of 480,000 points was drastically reduced to less than one hour i.e. 38 min for data acquisition, plus maximum 15 min for sample, electron beam, hardware and software setup.

Quantitative analysis of a bulk sample requires that the composition of the sample is homogeneous over the analyzed volume. For inhomogenous samples the calculation of the matrix effects is not correct and this can lead to wrong results in the element concentrations. For samples containing a layer structure a different quantitative evaluation has to be applied. This can be provided with the standard-based analysis in ESPRIT in combination with the STRATAGem software.

The measurements discussed in this document relate to a Cr-Ni-steel sample, the composition of which was originally determined with XRF and S-OES. Steel analysis using EDS generally deals with calculating the content of elements in the intermediate atomic number range through evaluation of the K-lines of the X-ray spectrum.

Using an automated scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) to find and positively identify gunshot residue (GSR), has been an accepted method for forensic applications for quite a number of years.

In the last decade, the EBSD technique has evolved - thanks to its combination with EDS - from being a tool for texture quantification to a complete microstructure characterization method. It is now more systematically used for quantifying grain size, phase distribution, grain boundary analysis and phase identification. EBSD analysis has become a standard analytical tool in Earth Sciences.

The determination of different mineral phases through backscattered electron (BSE) detectors is a common task in mineralogy. This approach however has limitations. If minerals with different composition but similar average atomic number are viewed with a BSE detector there is very little if no material contrast to be observed. This shortfall can be overcome through use of X-ray elemental maps. The innovative XFlash® 4010 SDD allows extremely high input and output count rates, hence elemental maps can be performed in about one tenth of the time required by conventional Si(Li) detectors.