[en] In this work, the synthesis using the carbo-reduction of zirconia route allowed synthesizing fine powders with variable stoichiometries of zirconium oxycarbide ZrC_xO_y. A structural and microstructural study by transmission electron microscopy has enabled to speculate the elementary mechanisms governing the reaction of zirconia carbo-reduction. The development of a numerical model taking into account the densification of a powder sample of zirconium oxycarbide revealed the presence of thermal and mechanical gradients with high amplitudes. The use of 'flash' sintering or SPS (Spark Plasma Sintering) has made possible the development of dense monoliths of zirconium oxycarbide with fine and homogeneous microstructures in order to maintain excellent use properties. Using analytical models derived from creep laws, the study of the elementary mechanisms governing creep and sintering highlighted the predominant role of dislocations in the case of a high stress thermomechanical treatment. (author)