Use and Perspective of X-Ray Diffraction in Science and Technology of Ceramic Coatings
X-ray diffraction provides a major tool to investigate the relation between the properties of a coating/substrate composite and its microstructure. Stresses, compositions, stress-depth profiles and composition-depth profiles can be determined. Further, microstructural parameters as crystallite size and microstrains can be obtained. The role of the penetration of X-rays deserves special attention, in particular when analysing thin coatings.
In various CVD TiC coating/substrate systems the strain (and stress) can be predicted quantitatively from thermal shrinkage. In some of these systems stress relaxes partially by strain-accommodating processes either in the layer and/or in the substrate.
In commercial CVD coatings foreign elements can be present either in solid solution or as a second phase and these can significantly influence the microstructure and (mechanical) properties.
In the surface (compound) layer of nitrided steels both stress and composition depth profiles occur. The stress profile is caused by the thermal shrinkage and by the composition-depth profile. Partial strain accommodation occurs due to the presence of pores.
KeywordsPorosity Anisotropy Ferrite Austenite Shrinkage
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