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Diffusion of Degradation Products in Ceramic Moldings during Pyrolysis: Effect of Geometry
Author(s) -
Matar Samir A.,
Edirisinghe Mohan J.,
Evans Julian R. G.,
Twizell E. H.
Publication year - 1996
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1996.tb07938.x
Subject(s) - ceramic , materials science , pyrolysis , diffusion , composite material , porosity , cylinder , molding (decorative) , polymer , degradation (telecommunications) , phase (matter) , thermodynamics , geometry , chemical engineering , chemistry , mathematics , organic chemistry , engineering , telecommunications , computer science , physics
A general equation applicable to a sphere, an infinite plate, and an infinite cylinder is used to calculate the transient diffusion of degradation product in a ceramic molding during pyrolysis. The solution includes the concentration‐dependent diffusion coefficient for diffusion of monomer in its parent polymer which forms the continuous phase in the ceramic in the as‐molded state. In the early stages of pyrolysis, before continuous porosity has developed, the model searches for the critical heating rate above which defects are produced. Reasonable agreement is obtained with experimentally measured critical heating rates for 3‐mm‐thick plates.