University of Craiova, A.I. Cuza 13, 1100 Craiova, Romania
A study on the influence of tabletting pressure upon the internal morphology of Fe2O3-Cr2O3 catalytic system shows the behaviour of that system at crystallite level or even below it. On increasing tabletting pressure of catalytic powder, remanent stresses are left in the tablets formed which can be calculated in terms of the remanent strain. The macrostresses are constant and small at tabletting pressures ranging within 108 − 5 × 108 Pa and increase linearly between 6 × 108 and 14 × 108 Pa. The microstresses take measurable values only in samples tabletted at pressures higher than 7 × 108 Pa. Besides the formation of remanent stresses, the increase of tabletting pressure brings about the overall change of porous structure and mechanical resistance of the catalytic system. The remanent stresses that appeared at tabletting result in cracks along some planes which, in most instances, are parallel to the planar faces of tablets. The maximum acceptable tabletting pressure of the catalytic system studied amounts to 5 × 108 Pa.
(Received March 30 2001)
(Revised July 9 2001)
(Accepted July 9 2001)
(Online publication December 15 2001)