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Vacuum Hot‐Pressing of Magnesium Aluminate Spinel
Author(s) -
RUMMLER DONALD R.,
PALMOUR HAYNE
Publication year - 1968
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.1151-2916.1968.tb15946.x
Subject(s) - porosity , spinel , materials science , strain rate , magnesium , hot pressing , dislocation , composite material , oxide , aluminate , mineralogy , stress (linguistics) , pressing , metallurgy , cement , chemistry , linguistics , philosophy
The densification kinetics of magnesium aluminate spinel during vacuum hot‐pressing were studied between 1175° and 1460° C and from 500 to 5100 psi. A phenomenologi‐cal rate equation, which suggests a logarithmic relation between strain rate and porosity, excellently described the observed densification. Treating porosity as an independent variable was shown to be reasonable; it does not functionally restrict porosity as a modifier of the applied stress. The strain rate dependence on porosity decreased at a porosity of approximately 0.15. Below 1350° C the densification characteristics were similar to those reported for other oxide systems. At 1450°C an increase in the stress dependence of the densification rate and an interaction between stress and porosity suggested that plastic flow by dislocation motion was an operative mechanism during densification.