Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (EDX) used on the cross-sections of the coated sample to determine the scale thickness and elemental composition.
During oxidation of protective coating MCrAlY (Bondcoat) on nickel superalloys formed Al2O3 layer (thermal grown oxide or TGO) with thickness of a few micrometers.
If this layer is thicker than 10 micrometers, or will comprise Cr2O3, it means that the coating has been overheated (> 900 ° C).
EDS is mainly for determining element composition and distribution within materials, therefore I do not think it could be used for oxidation states analysis. In metallorganics, we normally use XPS to determine metal valency. Sometimes, the coordination number and metal-oxygen bond length can also be used as a reference.
I agree with Vadim, X-ray Diffraction is propably the best and most accurate way to identifying your specimen's atomic/molecular structure. I would however suggest to take several measurements on diferent surface areas to get a holistic overview.
EDS is extremely useful tool in corrosion research. It can give distribution of elements through corrosion layer/corrosion flake and provide valuable information/hints for identifying oxidation phases. However, in contrast with for example XRD it cannot positively identify phases. In addition for dependable results you need to have good EDS system, good set of standards (such as hematite and magnetite when studying Fe corrosion), and, most important, good operator.
P.S. For complex corrosion (multiple phases) XRD alone will not give all results you need.
Glancing Angle XRD (GAXRD) is a good technique to determine the nature of a thin film of oxide on a substrate
.
It is not an easy task to deduce the nature of oxides from EDS since the quantification of light elements (C, N,O,..) is always difficult. If you have a reference sample, you may expect to get the information that you need.
XRD would be an alternative, if you have the possibility to do.
Agree with Mr. Qi Yang. Scanning electron microscopy coupled with EDS will give you clear picture. Then can be confirmed by X-ray Diffraction
XPS (X-Ray Photo electron Spectroscopy) could be a good tool to determine the type of oxides and their stoechiometry on a thickness of 1-2 microns.
SEM/EDS and X-Ray diffraction will give you near-surface information, and SEM/EDS won't be able to tell you the nature of the oxides but only the amount of elements present at the surface (could be from the oxides or from the substrate). Remember that some light elements could not be quantified by EDS. XRD will be able to determine the type of oxides if you have an idea of the type of oxides you might be finding.
Drawback of XPS, the analysis could be longer than XRD. Besides, you won't find the equipment in all research labs.
Oxydes cannot be assessed quantitatively eitheir in surface or in bulk metal but qualitatively by the methods mentioned above by Jouiad as well as by GEDOES. However, you can estimate the volume fraction in the specific area by the coupled SEM-TEM techniques.
Oxide formed can be known by using EDS, XRD, and Raman spectroscopy. For quantification, specific weight loss can be used and the thickness can best be determined using cross-sectional SEM/FIB images. In fact, it can be measured directly with the micron bar during analysis. The morphology can be determined by microscopy, SEM,TEM, and so on. Kindly check some of our work in this area. Odusote et al.
EDScan give the elemental percentage not the chemical compounds and its various forms however high magnication of SEM image can give a fare idea about the oxide types provided you have the basic knowledge about the shapes of varous oxide layers, in a particular corroding element or alloy
Dear Randhir,
ED scan and XRD is best for elemental/ chemical composition percentage, SEM/TEM at high magnifications is best for morphology, fractography study, size, texture and it can also be used for oxide characterizations. But it may lack in roughness or corrosion layer identification on surface if there any;
Why do not you go with XPS(in case any corrosion found on substrate), which is best for bulk and surface characterizations study.
Ashish
Suggest the following paper:
https://www.sciencedirect.com/science/article/abs/pii/S0925838818307771
- Badges
- Science method
- Similar topics
- Mathematics
- Statistics
- Statistical Techniques
- Structural Equation Modeling