ISSN:
1662-9779
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Physik
Notizen:
Internal stresses are very important for the performance of protective hard coatings. Tensile stressesfavour the formation and propagation of cracks, inducing fracture and corrosion. Mediumcompressive stresses hinder fatigue. But high compressive stresses, typically for hard coatingsproduced by PVD (physical vapour deposition) processes, support delamination in order to relax thestored elastic energy. However notwithstanding its relevance, the internal stresses are only seldomused for the optimisation and quality control of hard coatings in industry. This unsatisfying situationis caused by the deficit in efficient measuring methods. The results of thin sheets, where the stressescan be simply measured by their curvature, are not necessarily representative for the coating ofthicker parts. The conventional XRD (X-ray Diffraction), based on angle-dispersive evaluationneeds expensive devices and is rather time consuming. The energy-dispersive technique opens newpossibilities. It is based on polychromatic radiation. The interference of the lattice plane reflectionscorresponding to the Bragg-equation is investigated by the diffraction intensity of the differentwavelength (or photon energies), not by varying the Bragg-angle as in conventional XRD. Hence,the whole diffraction pattern can be obtained in one shoot without the use of any goniometer. Thisallows the construction of small and compact measuring devices and the reduction of measuringtime to a few minutes. The capability of the ED-XRD (Energy Dispersive X-ray Diffraction) isdemonstrated for titanium nitride and chromium nitride films deposited by cathodic vacuum arcwith varying parameters. Comparisons were made with the much more time-consuming AD-XRD(Angle Dispersive X-ray Diffraction) for residual stress analysis. The results of both methods are ingood agreement
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.130.39.pdf
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