| A new approach was developed to examine reaction and sintering of ceramics in a combined dilatometer and mass spectrometer apparatus. Background reactions in the graphite furnace were first studied. The evolved species could be assigned to carbon dioxide, carbon monoxide, oxygen, water, and cyanogen. The intensity data from the mass spectrometer indicate that trace oxygen reacts with the graphite to form the carbon dioxide and carbon monoxide.; The decomposition and sintering of calcium carbonate was studied in this apparatus. Kinetic rate parameters for the decomposition, initial stage of shrinkage, and relative density were analyzed by reaction and sintering models using integral methods of analysis. Both the decomposition and relative density were reasonably well described with an activation energy of 115–120 kJ/mol over the full range of conversion over a wide range of temperatures. The initial stage of shrinkage was described by a diffusion mechanism with an activation energy of 225 kJ/mol.; Sintering kinetics of the SrTiO3 and Y2O3 -doped SrTiO3 were investigated under isothermal and constant-heating-rate conditions in argon and nitrogen. The grain boundary diffusion mechanism was dominant in these sintering experiments at temperatures higher than 1300°C. Different sintering behaviors were observed for SrTiO3 and Y 2O3-doped SrTiO3 when sintered in argon. The experimental data were analyzed by the master sintering curve method and activation energy of sintering was determined.; A model was developed to describe flow in porous media from the thermal decomposition of binder in three-dimensional bodies with anisotropic permeability. The results from numerical solution of the unsteady-state partial differential equation were compared to those obtained from an analytical solution to the steady-state equation. Scaling relationships for the buildup of pressure in terms of the dimensions of the body, the rate of reaction, and the permeability were also derived. |
