DI-UMONS : Dépôt institutionnel de l’université de Mons

Recherche transversale
Rechercher
(titres de publication, de périodique et noms de colloque inclus)
2002-01-01 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Descamps J.-C., Gonon Maurice , "Characterisation by XRD of surface residual stresses due to machining in fine ceramics" in CIEC 8, Lyon, France, 2002

  • Codes CREF : Matériaux céramiques et poudres (DI2744), Contrôle des matériaux (DI2830)
  • Unités de recherche UMONS : Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) CHARACTERISATION BY XRD OF SURFACE RESISDUAL STRESSES DUE TO MACHINING IN FINE CERAMICS. M. Gonon, J-C. Descamps Service de Science des Matériaux, Faculté Polytechnique de Mons (Belgium) The first aim of this work was to investigate if the surface residual stresses generated during the machining of fine ceramics as silicon nitride or alumina can be measured by using the X-ray diffraction method. The characterisation of the surface stress by XRD is based on the measurement of the ?2? shift of a selected diffraction peak. The 2? angle being linked to the distance between atom planes in the structure, the shift ?2? is linked to the elastic strain ? of the unit cells by the equation ? = - ?? . cotg?. This strain is measured in a direction normal to the reference plane of the diffraction device. Therefore, by orienting the sample with several selected angles ? and ?.with regard to the reference plane it is possible to measure the strain tensor and then to calculate the stress tensor from the elastic properties of the sample. By comparison to powder standards of same crystalline nature or to reference samples in which stresses were relaxed, the machining induces measurable residual stresses. However, all samples lead to curves ? versus sin2? characteristic of stress gradient from the surface to the bulk. Calculations were performed to estimate the curve stress versus depth. Then samples machined under different conditions (depth of cut, cutting rate,…) were compared to check if the conditions used leads to stress variations sufficient to be measured. However, when using usual machining conditions no significant differences are observed. On the contrary, the use of drastic conditions increases the measured stresses but also leads to surface damages (cracks).