STUDY OF SOME MECHANICAL PROPERTIES OF THIN HARD COATING CHROMIUM CARBIDES
Mots-clés :
Chromium, carbides, hard coating, nanoindentationRésumé
In the present work, some mechanical properties of chromium carbides coating on steel substrates were
studied. The samples were prepared by d.c. magnetron sputtering of a pure Chromium (Cr) layer on steel
substrates containing 1%wt of Carbon. The system (substrate/coating) was then annealed in vacuum at a
temperature at which the carbon of the substrate may diffuse into the Cr metallic film. This fact leads to the
formation of chromium carbides, which are identified by X-ray diffraction as Cr7C3, Cr23C6 and (Cr,Fe)7C3.
The study by nanoindentation shows that the microhardness decreases with increasing of annealing
temperature until 800°C, then increases rapidly to reach a maximum (≈2800 Kg.mm-2) at 1000°C. The
internal stresses, measured by X-ray diffraction, are compressive at 900°C and tensile at 1000°C in the
chromium coating. Nevertheless, they are tensile in the substrates regardless the temperature. The sign
change of the stresses in the coating is probably due to the phase transformation (Cr7C3→(Cr,Fe)7C3)).
Téléchargements
Références
- Richardt A. et Durand A.-M., "Le vide, les couches minces -
les couches dures", Ed. In Fine, Paris, (1994).
- Collonges R., "La non stoechiométrie", Masson & Cie
éditeurs, Paris (1971).
- Sundgren E. and Hentzell H.T.G., J. Vac. Sci. Technol. A4
(5), (1986), p. 2259.
- Chekour L., Thèse de Magister, Université de Constantine
(1987).
- Harkati C., Thèse de Magister, Université de Constantine
(1998).
- Chaussin C. et Hilly G., "Métallurgie", Tome 1, Ed. Dunod,
Paris (1978).
- Castex L., Lebrun J.L., Maeder G. et Sprauel J.M.,
Publication n°22, ENSAM, Paris (1981)
- Harkati C., Chekour L., Halimi R., 6ème Journées
Maghrébines sur les Sciences des Matériaux, Annaba, 9-11
Novembre (1998).
- Chekour L., Krier J., Halimi R., Cornet A., Journal de
Physique III, C4, (1996), p. 251.
- J. A. Thornton and D. W. Hoffman, J. Vac. Sci. Technol. A3,
(1985), p. 576.
