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IFJ PAN

IFJ PAN. Development of chemically reactive nuclear beams - BEAMLAB Subt ask 2: Material compatibility in reactive gas atmospheres. J.W. Mietelski, R. Misiak, M. Bartyzel, B. Wąs (Institute of Nuclear Physics Polish Academy of Sciences). IFJ PAN. Contents

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IFJ PAN

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  1. IFJ PAN Development of chemically reactive nuclear beams - BEAMLAB Subtask 2: Material compatibility in reactive gas atmospheres J.W. Mietelski, R. Misiak, M. Bartyzel, B. Wąs (Institute of Nuclear Physics Polish Academy of Sciences) BeamLab meeting

  2. IFJ PAN • Contents • Preparation of the surface of tantalum specimens • Oxidation kinetics of Ta at: • - atmospheric pressure • - lowoxygen pressures • 3) Topography of the surface of tantalum specimens BeamLab meeting

  3. IFJ PAN • Tantalum plates were cut from 100μm Ta foil in two dimensions: 10 x 10 mm and 7 x 10 mm • These plates were washed in tetrachloromethane for one hour and in acetone for half an hour using a ultrasonic cleaner • After washing the Ta surface were cleaned with wipes - Sontara „MicroPure100” using acetone • Quartz tubes were washed with hot concentrated nitric acid and then washed with deionized water BeamLab meeting

  4. IFJ PAN • Contents • Preparation of the surface of tantalum specimens • Oxidation kinetics of Ta at: • - atmospheric pressure • - lowoxygen pressures • 3) Topography of the surface of tantalum specimens BeamLab meeting

  5. IFJ PAN Tantalum plates were oxidized between for 5 to 60 minutes at temperatures between 790 and 990 K. A flow rate of oxygen - 3.6 mL/min was controlled by Brooks Mass Flow Meter. The oxidation kinetics were measured by thermogravimetry. Figure 1. Apparatus for oxidation of Ta foil at atmospheric pressure: 1 - quartz column (inside diameter 11 mm); 2 – Ta plate (10x10 mm;); 3- resistance oven; 4 – thermocouple; 5 – quartz plug; 6 - O2 gas; 7- Brooks Mass Flow Meter. BeamLab meeting

  6. IFJ PAN Figure 2. Weight gain/area vs. oxidation time for different temperature. Figure 3. (Weight gain/area)2vs. oxidation time for different temperature. These plots (Fig. 3) show an approximately straight-line behaviour indicative of parabolic oxidation kinetics, Eq. 1: [1] where: - is weight gain, A is the sample surface area, - is the parabolic rate constant, and t is the oxidation time. BeamLab meeting

  7. IFJ PAN At temperatures from 890 K to 990 K the oxidation follows a linear rate law (Fig. 4), Eq. 2: [2] The obtained parabolic oxidation rate constantskgat temperature range of 790 to 840K (Fig. 3) and linear oxidation rate constants klat temperature range of 890 to 990K (Fig. 4) were used for determination of an activation energy –Q by Arrhenius equation- Figure 4. Weight gain/area vs. oxidation time for different temperature. Activation energies for Ta oxidized for two different temperature ranges. where:R is the gas constant, T is the temperature and is the pre-exponential factor. BeamLab meeting

  8. IFJ PAN • Contents • Preparation of the surface of tantalum specimens • Oxidation kinetics of Ta at: • - atmospheric pressure • - lowoxygen pressures • 3) Topography of the surface of tantalum specimens BeamLab meeting

  9. IFJ PAN Oxidation of tantalum has been studied at 1003-1363 K and at oxygen pressures from 1x10-3 to 2,5x10-4 mbar (which corresponds to the flow rate of oxygen from 7,2 mL/min to 1,8 mL/min). BeamLab meeting

  10. IFJ PAN Figure 5. Weight gain/area vs. oxidation time for different temperature. The linear oxidation rate constants klat temperature range of 1003 to 1363 K (Fig. 5) were used for determination of an activation energy –Q by Arrhenius equation. Activation energy for Ta oxidized at pressure 6x10-4 mbar was 67,4 kJ/mol. BeamLab meeting

  11. IFJ PAN Figure 6. Effect of oxygen pressure on the oxidation of tantalum. Figure 7. Weight gain/area vs. oxidation time for 1160 K. BeamLab meeting

  12. IFJ PAN • Contents • Preparation of the surface of tantalum specimens • Oxidation kinetics of Ta at: • - atmospheric pressure • - lowoxygen pressures • 3) Topography of the surface of tantalum specimens BeamLab meeting

  13. IFJ PAN a b c Appearance of tantalum specimens: a- before experiment b- 90 min at 1003 K and 5x10-6 mbar c- 90 min at 1160 K and 5x10-6 mbar BeamLab meeting

  14. IFJ PAN c d Appearance of tantalum specimens: c- before experiment d- 90 min at 1363 K and 5x10-6 mbar BeamLab meeting

  15. IFJ PAN Chemical analysis – EDS Texp = 990 K, texp.=30 min, p= atmospheric pressure (flow rate of oxygen 3,6 mL/min) BeamLab meeting

  16. IFJ PAN Chemical analysis – EDS Texp = 1363 K, texp.=30 min, p= 6x10-4 mbar (flow rate of oxygen 3,6 mL/min) BeamLab meeting

  17. Thank you for your attention Acknowledgements to prof. M. Parlińska and G. Gruzeł from Department of Soft Matter Research IFJ PAN for SEM-EDS measurements. BeamLab meeting

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