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Vacuum Vaporization in the System MgO‐Cr 2 O 3
Author(s) -
SATA TOSHIYUKI,
LEE HONG LIM
Publication year - 1978
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.1151-2916.1978.tb09320.x
Subject(s) - vaporization , torr , chemistry , analytical chemistry (journal) , materials science , thermodynamics , physics , chromatography
The vaporization of the system MgO‐Cr 2 O 3 was studied in a vacuum of 10 −5 torr (10 −3 N/m 2 ) at 1500° to 1700°C using the Langmuir and Knudsen methods. It was found that the phases in the system vaporize nearly congruently and the logarithm of the vaporization coefficient, α, of MgCr 2 O 4 increases linearly with increasing reciprocal temperature. Alpha tends to unity at a temperature near the melting point (2525±23°C). The additivity rule can be applied to the Langmuir vaporization rates on the basis of the surface area ratios of the phases in the 2‐phase system MgO‐Cr 2 O 3 . The enthalpies of vaporization of MgCr 2 O 4 were 695.0 and 549.2 kcaVmol for activated and equilibrium processes, respectively.