STRÜBBE Carsten University Politehnica of Timisoara

Spoluautoři SERBAN Viorel-Aurel, MARGINEAN Gabriela, BRANDL Waltraut

The high temperature thermo cyclic behaviour of Ni-Cr-B-Si coatings was investigated in order to define the suitability of such materials for different applications. The samples were cyclically oxidized in air at 600°C, 700°C and 800°C for 120 cycles in an automatic test station.The surface morphology and the phase composition of the grown oxide scales were characterized by means of scanning electron microscopy combined with energy dispersive X-ray (SEM/EDX) and by X-ray diffraction (XRD) technique. The obtained results demonstrate the importance of silicon on the stability of the formed oxide scale (free of micro cracks, no spallation). This element is able to form beside chromium, a dense protective layer on the sample surface, protecting it against further degradation induced by the atmosphere in different high temperature applications. Moreover, the increased chromium content of the feedstock powder (from 10,00wt% in previous work to 12,5wt%) demonstrated no appearance of internal oxidation for all investigated Ni-Cr-B-Si coating.

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