Objective In order to provide the mechanical data needed to design a ceramic component for a combustion engine, mechanical testing of a silicon nitride material and a sialon material will be performed in various conditions: static and cyclic loading; high temperatures; diesel exhaust gas environment; with special attention paid to the specific influence of the aggressive atmosphere.The fracture behaviour will be examined under 2 approaches assuming that the failure is dictated by a subcritical crack growth law, and by a creep law, the subcritical crack growth being a consequence of a local creep.These approaches will be developed with a view to their application in finite elements programmes for the lifetime prediction of ceramic components. In parallel, the physicochemical mechanisms responsible for the degradation of the mechanical properties of ceramics in the aggressive environment will be identified.This programme gives important results on:tensile and bending creep;influence of the environment (air or exhaust gases and temperature) on corrosion and subcritical crack growth (static or cyclic);relation between microcracks (natural flaws) and macrocracks (test specimens);testing of a postprocessor to a 3-dimensional finite element programme which gives failure probability of components;development of specific numerical posttreatments to give a failure probability of components after damage (creep and crack growth in static and cyclic loading).In order to provide the mechanical data needed to design a ceramic component for a combustion engine, mechanical testing of sintered silicon nitride (SSN) materials (with glassy and recrystallized intergranular phases) has been performed under various conditions (static and cyclic loading, high temperatures). Special attention has been payed to the specific influence of the aggressive atmosphere of diesel exhaust gases. This work has necessitated the development of specific testing devices and models to describe the material behaviour.SSN with recrystallized intergranular phases exhibits good mechanical properties (strength, oxidation, creep) up to 1100 C (900 C for glassy intergranular phases SSN). No significant effect of frequency on lifetime has been found or any effect of exhaust gas on high temperature mechanical properties. Creep behaviour, however, is very sensitive to loading direction, with a greater creep rate in tension than in compression.Postprocessors to finite element codes have been developed to predict lifetimes of ceramic components for a given failure probability under the testing conditions of this programme.IN ORDER TO PROVIDE THE MECHANICAL DATA NEEDED TO DESIGN A CERAMIC COMPONENT FOR A COMBUSTION ENGINE, MECHANICAL TESTING OF A SILICON NITRIDE MATERIAL AND A SIALON MATERIAL WILL BE PERFORMED IN VARIOUS CONDITIONS - STATIC AD CYCLIC LOADING, HIGH TEMPERATURES, DIESEL EXHAUST GAS ENVIRONMENT - WITH A SPECIAL ATTENTION PAID TO THE SPECIFIC INFLUENCE OF THE AGGRESSIVE ATMOSPHERE.THE FRACTURE BEHAVIOUR WILL BE EXAMINED UNDER TWO APPROACHES ASSUMING THAT THE FAILURE IS DICTATED: 1.- BY A SUBCRITICAL CRACK GROWTH LAW 2.- BY A CREEP LAW, THE SUBCRITICAL CRACK GROWTH BEING A CONSEQUENCE OF A LOCAL CREEP.THESE APPROACHES WILL BE DEVELOPED IN VIEW OF THEIR APPLICATION IN FINITE-ELEMENTS PROGRAMMES FOR THE LIFETIME PREDICTION OF CERAMIC COMPONENTS.IN PARALLEL, THE PHYSICO-CHEMICAL MECHANISMS RESPONSIBLE FOR THE DEGRADATION OF THE MECHANICAL PROPERTIES OF CERAMICS IN THE AGGRESSIVE ENVIRONMENT WILL BE IDENTIFIED. Fields of science natural scienceschemical scienceselectrochemistryelectrolysisnatural scienceschemical sciencesinorganic chemistrymetalloidsengineering and technologymaterials engineeringceramicssocial scienceslaw Programme(s) FP1-BRITE - Multiannual research and development programme (EEC) in the fields of basic technological research and the applications of new technologies (BRITE), 1985-1988 Topic(s) Data not available Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator REGIENOV GROUPEMENT D INTERET ECONOMIQUE* Address 9-11,quai alphonse le gallo 13 92100 Boulogne-billancourt France See on map EU contribution € 0,00 Participants (4) Sort alphabetically Sort by EU Contribution Expand all Collapse all ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS France EU contribution € 0,00 Address Boulevard saint-michel 60 75272 Paris See on map FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG E.V.* Germany EU contribution € 0,00 Address Woehlerstrasse 11 79108 Freiburg (in breisgau) See on map GIE PSA Peugeot Citroen France EU contribution € 0,00 Address Avenue de la grande armee 75 75116 Paris See on map VOLKSWAGEN AG Germany EU contribution € 0,00 Address Berliner ring 2 Wolfsburg See on map Links Website Opens in new window
