Vaporization studies of oxide systems using a QMS-420 mass spectrometer

Abstract

The present paper is a continuation of the systematic study of vaporization processes and thermodynamic properties of oxide systems by high temperature mass spectrometric method. The features of the vaporization of the CaOB 2O 3, B 2O 3Al 2O 3 and ZnOP 2O 5 systems, such as the association and dissociation processes, are considered from the point of view of the acid-base concept. The reliability and accuracy of thermodynamic data obtained in the present work is in agreement with the results found earlier using the exchange equilibria method in slags, high temperature mass spectrometric method and by calculated values based on various approaches. A modification of quadrupole QMS-420 mass spectrometer is suggested, that can be useful for high temperature thermodynamic studies. Arrangement of the vaporizer containing a molybdenum block with four tungsten effusion cells and heater from tungsten coil is discussed. The special rotating assembly allowed the identification of the vapour composition from the samples situated in each of four effusion cells in the same experiment up to 1900 K is described.