Microstructure evolution of ceramics during sintering: an analysis based on local image analysis measurements in the vicinity of controlled defects

UO2 powder containing 5% of almost spherical defects of controlled size have been sintered. The defects were prepared with the same powder by pre-sintering either the natural powder aggregates or partially milled pressed powder. Systematic image analysis was performed to get the local microstructure features inside the defects and in the matrix outside the defects. The set of results is used here as a sintering database with three identified sintering 'constraint' parameters (compaction level C0, radial distance r to the defect edge, and sintering 'history' H) and three microstructure 'responses' (pore volume fraction VVP, pore mean diameter DP, and grain mean diameter DG). Data analysis in the 3D responses space shows that these variables are not independent but define a unique surface, on which each point corresponds to a set of constraints (C0,r,H). (authors)