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Vaporization processes of borosilicate coatings studied by high temperature mass spectrometry and using an induction plasma generator
Author(s) -
Stolyarova V. L.,
Archakov I. Yu.,
Gordeev A. N.,
Yakushin M. I.,
Shultz M. M.
Publication year - 1993
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290070203
Subject(s) - chemistry , vaporization , borosilicate glass , coating , plasma , volatilisation , analytical chemistry (journal) , mass spectrometry , silicon , environmental chemistry , chromatography , organic chemistry , quantum mechanics , physics
A new approach has been applied to study processes which take place during the thermochemical action of air (or other) plasma on heat protection materials. Vaporization processes of the borosilicate coating of ‘Buran's’ heatprotective tiles, both the initial state and after rf‐entry simulation testing (up to 100 landings), were investigated by the Knudsen mass spectrometric effusion method. Modelling of the thermochemical action of the shock‐layer plasma onto the front surfaces of real‐scale tiles was carried out by using an induction plasma genetor of 500kW power. It was established that the thermochemical action of the plasma causes, essentially, a decrease of vapour pressure over the coating. However, despite this decrease, the pressures observed are significantly higher than those over the SiO 2 –B 2 O 3 system at the same temperature, due to gas‐phase SiO production by reaction between boron and silicon oxides and SiB 4 , which are contanied in the coating. The data available aiiow one to postulate the presence of the SiBO molecule in the gas phase. Data on mass‐loss rates obtained by direct measurments after re‐entry simulation compared nwell with the values calcuted from mass spectrometric data. It is suggested that the difference observed is caused by thermochemical action of atomic oxygen on the coating.