SEM(scanning elecctron microscopy)
Device designation: JSM 6460
EDX(energy dispersive X-ray), used for the analysis of the chemical configuration (semiquantitative determination)
Device designation: X-Flash Detector 3001
Manufacturer: Bruker AXS (former: Röntec)
The WZR ceramic solutions GmbH is working with a scanning electron microscope 6460 made by JEOL which is equipped with a energy dispersive X-ray by Bruker(former Röntec). The installed detector has a so-called light element window which makes the capture even of the light elements like oxygen, carbon, fluorine and nitrogen possible.
Scanning electron microscopy in combination with energy dispersive X-ray analysis (SEM/EDX)
The scanning electron microscopy is a nondestructive imaging procedure, comparable to the light microscopy, but it clearly excels it on many levels.
One major difference between those types of microscopy is that the imaging with the scanning electron microscope is carried out by scanning the sample with an electron beam. The electron beams are not constricted by the limits of the visible light and, hence, they lead to a substantially higher image resolution. Therefore it is possible to examine materials at very high magnifications, depending on the material and the area of application.The interaction of the electron beam with the sample causes a variety of interactions and leads to the emission of various radiations from the sample. Those different radiations are used for the scanning electron microscopy analysies. Thus it is possible to examine the topographies of samples by using the secondary electrons (SE) which are emitted directly from the sample surface. Due to the high depth of focus for the obtained signal, nearly three-dimensional images can be obtained using SE imaging. Compositional information can be obtained by using back scattered electrons, which are produced by the deflection of the electron beam through interactions with the atoms. The energy of the back scattered electrons is depending on the mass of the element they are interacting with. Therefore differences in atomic mass can be detected through intensity variations. Another important interaction of electron beam and sample is the emission of x-ray quantums which are characteristic for each element. This radiation is detected by an energy dispersive X-ray microanalysis and makes it possible to analyze the chemical composition of the sample. The analysis can be carried out for single points as well as for windows or lines on a selected area (see below). The characterization of the surface and sample texture in combination with the analysis of the chemical composition makes the SEM and the EDX an indispensable method for the material characterization and the damage analysis.
Therefore this procedure allows statements about the material state and can provide conclusions on wrong material choice as well as, production and processing mistakes. Nearly all materials can be examined by using the SEM: biological, ceramic and metallic materials. We at the WZR ceramic solutions Ltd have specialized on the investigation and evaluation of ceramic and metallic materials and applications. The samples can be examined as bulk pieces, dispersed samples or as polished sections.
Examples of methods
It is possible to carry out element analysis in detail up to a few µm.
Chosen elements can be determined along selected profiles.
Similar to the illustration of maps it is possible to depict the allocation of elements over the image section. With the defined color assignment a sorted overview on the allocation of elements is possible.
Examples of use
Using the SEM/EDX the following attributes can be analyzed:
- microstructure, composition of the material
- structural changes
- chemical compounding of the material
- impurities, embedding
- porosity, pore distribution
- cracks and their allocation
- modifications of the material influenced by e.g. reactions on temperature
- modifications of the material triggered by reactions with contaminants
- infiltration and accumulation
- corrosion signs
- mechanical stress
- surface and material defects
- construction and processing errors
- evaluation of surfaces