Modeling the effect of gas transport on the formation of defects during thermolysis of powder moldings
- Department of Materials Technology, Brunel University, Uxbridge, Middlesex, UB8 3PH (United Kingdom)
- Department of Mathematics and Statistics, Brunel University, Uxbridge, Middlesex, UB8 3PH (United Kingdom)
The removal of binder from ceramic or metal moldings by thermolysis involves the transport of degradation products through the parent organic phase and the vacated porous body. A numerical model has been developed to combine an equation which takes into account different gas-flow regimes with an equation for the transport of organic molecules in molten polymers. Computer modeling reveals the critical heating rate above which defects occur due to boiling of the polymer-monomer solution at the center of the molding. The situation in which a porous outer layer of the molding develops, offering resistance to flow of the evolved monomer gas, is then treated. This gives rise to a moving boundary with a variable concentration of diffusant which is dependent on the surface flux, gas transport coefficient and thickness of the porous layer. The contributions of diffusion and viscous flow to gas transport are considered. {copyright} {ital 1996 Materials Research Society.}
- OSTI ID:
- 280122
- Journal Information:
- Journal of Materials Research, Vol. 11, Issue 4; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Method for molding ceramic powders
Process for molding complex beta''-alumina shapes for sodium/sulfur batteries