Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

X-ray-investigations of platinum layers on dense construction ceramics with regard to residual stresses and stressfree lattice constants.

Röntgenuntersuchungen an Pt-Schichten auf dichten Konstruktionskeramiken unter Berücksichtigung von Eigenspannungen und eigenspannungsfreien Gitterkonstanten
: Große, G.; Taut, C.; Stephan, D.

Delhez, R.; Mittemeijer, E.J.:
EPDIC 2. Proceedings of the Second European Powder Diffraction Conference 1992. Vol.2
Aedermannsdorf: Trans Tech Publications, 1993 (Materials science forum 133/136)
ISBN: 0-87849-661-0
European Powder Diffraction Conference (EPDIC) <2, 1992, Enschede>
Conference Paper
Fraunhofer IKTS ()
platinum layer; residual stress; silicon nitride ceramic; stressfree lattice constant; x-ray diffraction

The favourable properties of nonoxide ceramics, such as high bending strength, fracture toughness and chemical resistance, decrease at temperatures bigger than 1000 degree due to reactions of the ceramics with the attacking medium and as well as to the softening of the secondary glassy phase. The combination of the ceramics with other materials showing better corrosion and wear properties offers a possibility to suppress some of these decreasing processes. As a contribution to that, the influence of a platinum surface layer on the oxidation behaviour of dense silicon nitride was investigated. The characterization of the layers was performed by optical and electron microscopy and by X- ray diffraction. The X-ray investigations were carried out on 0.4./.1.5 mym thick Pt layers on Si3N4 samples. On a removed 1.5 mym thick layer it was measured for comparisons as well. For determination of the texture and the residual stress a psi-goniometer was used taking interferences of several lattice planes into account. The investigations show, that the layers have a 111-fibre texture. With increasing layer thickness the sharpness of texture decreases and the compressive stresses changes from about 450 MPa to 240 MPa. In order to analyze the lattice spacing-sin-square-psi- dependence, especially for the determination of the stressfree lattice constant, the special measuring directions, strainfree direction and ideal angle positions of texture, were used. The general usefullness of these special directions in the X-ray diffraction is discussed. By application of the grazing incidence it was attempted to characterize the depth depending changes in the 1.5 mym thick layer.