Ceramic testing with scanning electron microscopy
Characterization of surface and sample properties of technical ceramics
Scanning electron microscopy is a non-destructive examination method that allows both the surface of the sample (topography) and the chemical composition of the surface to be analyzed. The surface is scanned with an electron beam, creating an image that provides information about individual components.
WZR ceramic solutions uses a JEOL IT200 scanning electron microscope (SEM), which can also detect light elements such as carbon or oxygen via integrated energy dispersive X-ray spectroscopy (EDX). In contrast to the well-known light microscope, the scanning electron microscope offers the possibility of a magnification of up to 300,000 times combined with a high resolution and a large depth of focus, which enables an almost three-dimensional appearance of the sample.
WZR ceramic solutions GmbH is specialized in the investigation and evaluation of ceramic materials and applications. The samples can be examined as piece samples, as scattering preparations or as grindings in both low and high vacuum.
The following aspects can be examined by means of SEM/EDX:
- Microstructure evaluation, structure of the material
- Microstructural changes
- chemical composition of the components of a material
- Impurities, inclusions
- Porosity, pore distribution
- Cracks and crack distribution
- Material and material changes due to reactions taking place within the materials, caused e.g. by temperature effects
- Material and material changes due to reactions with foreign components, e.g. corrosive media, slags
- Infiltrations and deposits
- Signs of corrosion
- mechanical damages
- Flaws, material defects
- Manufacturing and processing defects
- Evaluation of layers
- Surface Ratings
What can scanning electron microscopy be used for?
Due to the characterization of surface and sample properties with simultaneous analysis of the chemical composition, scanning electron microscopy in combination with EDX is an indispensable method for material characterization and damage analysis. The method allows statements to be made about material properties and can provide conclusions about “unsuitable” material selection, manufacturing and processing defects. Almost all materials can be examined by scanning electron microscopy: biological, ceramic and metallic materials.
How is the analysis and imaging of ceramics performed?
The excitation of the sample with electron radiation causes interactions in the sample and leads to the generation of different radiations. These different radiations are used in scanning electron microscopic analyses. By means of secondary electrons (SE), topographies, e.g. for the investigation of fracture surfaces, can be analyzed and reproduced in three dimensions. With the back-scattered electrons (BSE) material contrasts can be detected.
The different material compositions express themselves in different grey shades. The areas with high atomic mass appear brighter than the areas with low atomic mass. The interactions in the sample due to the input of electrons generate characteristic X-rays. This radiation is detected by EDX (= energy dispersive X-ray spectroscopy) and allows the analysis of the chemical composition of the sample. The analysis can be performed for single points, but also for areas or lines over a selected area. In addition, the possibility of false-color display for visualization of the element distributions is offered.
What are the limits of scanning electron microscopy?
Due to the nature of the device, it is not possible to analyze liquid and gaseous samples. Furthermore, very light elements like H, He, Li (Be, B) cannot be identified with the EDX. In general, the EDX analysis is a semi-quantitative evaluation. Precise information on the weight % can be obtained by means of X-ray fluorescence analysis (XRF). The local resolution of individual measuring points is about 3 nm. For this purpose the samples (under vacuum) must not contain any volatile components and must have a maximum diameter of 110 mm at a height of approx. 25 mm.
What other chemical analyses for technical ceramics does WZR offer?
In addition to scanning electron microscopy, we at WZR ceramic solutions GmbH offer qualitative and quantitative X-ray diffraction analysis and X-ray fluorescence analysis in the field of ceramic testing.