SU1387072A1 - Method of measuring oxygen partial pressure - Google Patents

Description

(21) 4097163 / 24-21

(22) 05/26/86

(46) 04/07/88. Bul № 13

(71) Moscow State University. Mv Lomonosov

(72) And. D. Sorokin, 0. M. Vovk, E. B. Rudny and L. N. Sidorov (53) 621.384 (088.8)

(56) Chufalov G. I., Men I. A., Balakirev V. F., Zhuravleva G. G., Schepetkin A. A. Thermodynamics of the reduction of metal oxides. - M., Metallurgi, 1970.

Sidorov L.N., Sorokin, T. D., Nikitin, M.I., Skokan, E.V., Effusion Method for Determination of Negative Lons. - int. I. Mass-spectrom Ion Phys, 1981, V. 39, p. 311-325.

Piacente V., J. Matousek. Mass-spectrometric determination of the sodium overflow of the system NajO 2Si02 Silikaty XVII, 1973, no. 4, p. 269-279.

(54) METHOD OF MEASURING PARTIAL OXYGEN PRESSURE

(57) The invention can be used to determine the partial pressures of oxygen in high-temperature processes, in particular MHD generators, plasma chemistry, and the melting of metals. The method for measuring the partial pressure of oxygen is as follows. Additives are introduced into the system under study, giving negative oxygen-containing ions in a saturated system vapor, heating the system under investigation in an effusion chamber, ions are measured on a mass spectrometer, and the oxygen partial pressure is calculated by ion-molecular equilibrium. Substances giving negative oxygen-containing ions:, K2SO (SO, SO, 804), K, jCr04, (CrO ;, CrO;), NaPO, (PO, P0,). The method is highly sensitive (before) and does not require the determination of the sensitivity constant of the apparatus. 2 tab.

Q €

(L

with oo -J

The invention relates to the measurement of the partial pressure of gases in mixtures specifically to the measurement of the partial pressure of oxygen in nasium vapor pairs of complex composition, and can be used to determine the fractional oxygen partial pressures in high-temperature processes, in particular, MHD generators, plasma chemistry , when melting metals, as well as for analytical purposes.

The aim of the invention is to increase the sensitivity.

The method consists in adding substances to the system under study, giving negative oxygen-containing ions in a saturated vapor system, heating the system under investigation in an effusion chamber, measuring the ions on a mass spectrometer, and calculating the partial pressure of oxygen by ionic molecules. equilibrium.

Substances giving negative oxygen-containing ions:

, so ;,), k ,, cr04,

Na ,, Cr04 (CrO;, CrO;), NaPO, (POi, PO,).

Example. An additive of potassium chromate is introduced into the Na O SiO system, (50 mol.%), Which does not produce negative oxygen-containing ions in the pupped pair. Two experiments were carried out with different amounts of additive: in the first experiment, 150 mg of NajO SiO was taken as 10 mg, which was 2.05 mol.%, In the second case, 130 mg of NaiO-SiOj, 1.5 mg, which was 0 , 36 small.%. Substances are carefully ground in an agate mortar, the mixture is placed in an effusion chamber, heated to 1200-1344 K

In saturated vapor, CrOJCrO ions appear, which are recorded by a mass spectrometer. The ratio of ion pressure is calculated through the ratio of registered ion currents.

) 1 () MSSGO,).

p (sgo) iTcro;))

where P is the partial pressure of ions; 1 - measured ion current; Molecular weight ishov. Ion-1) molecular equilibrium

(JrO; +1/2 O, CrO;

calculate kyi ayu g kuc. nip .v ia

partial dal. H - Nie

P (o) EiciQil. (pssgo;) KpJ

 f i (i 0i) M (cro;) 1 iTcro,) tc.

50

five

about

five

0

five

0

five

The equilibrium constant (K) is calculated from the thermodynamic data of the participants in the equilibrium by known formulas or measured in experiments with a known partial pressure of oxygen.

The upper limit of the amount of an additive is determined by its effect on the activities of the components of the system and is 4 mol%. The lower limit is determined by the sensitivity of the apparatus and is about 0.1 mol%.

The partial pressure of oxygen in the SiOi system (50 mol.% Na, 0) is presented in Table. one.

In tab. Table 2 shows examples of substances that can be used as an additive to determine the partial pressure of oxygen. The last column calculates the minimum partial pressure of oxygen RMISH KOTdpoe oxygen can be measured by the proposed method.

The maximum partial pressure that can be determined by the proposed method is determined by the Knudsen evaporation limit and is 10 atm. Thus, the proposed method of measuring the oxygen partial pressure as compared with the known one can significantly increase the sensitivity of the measured oxygen partial pressures (up to atm) and also eliminate the contribution of residual gas pressure to the measured values and does not require the determination of the sensitivity constant of the equipment.

Claims (1)

Invention Formula The method of measuring the partial pressure of oxygen in saturated vapors of complex composition by the diffusion method, including heating the system under study in the diffusion chamber, mass spectrometric measurement of the ion currents of the vapor components, followed by calculating the partial pressure of oxygen In order to increase the sensitivity, the addition of substances that produce ions is introduced into the tested network, they are measured and calculated when the oxygen partial pressure of the oxygen oxygen-containing ion-molecular equilibrium. SOjSO, so, so ro ;, po; CrOj, CrO Spreadsheets table 2  k t ° - ( °.) Y - 3 °°  i; °° - ™