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The oxidation mechanisms of Cu54Ni45Mn1 (Constantan) tapes: Kinetic analysis

Abstract : The kinetic parameters, namely the triplet activation energy EA, model function f(alpha) or g(alpha) and pre-exponential factor A of the oxidation of Constantan tapes in 1 atm of oxygen have been determined from both isothermal and non-isothermal thermogravimetry. For isothermal experiments, with temperatures ranging from 650 degrees C to 900 degrees C, the results from direct conversion of the weight increase as a function of the time and curve fitting, are compared with the isoconversion method. For the non-isothermal experiments, with heating rates from 1 degrees C/min to 20 degrees C/min, comparison is made between the Friedman differential method and the integral methods of Kissinger, Ozawa and Li and Tang. All methods give apparent activation energies with relative standard deviations as low as 3%. The results converge to the identification of three stages in the oxidation behaviour. A parabolic law for reaction extents alpha below 15% with E-A = 246 +/- 7 kJ mol(-1), In A = 14.3, is followed by two linear stages with E-A = 244 +/- 4 kJ mol(-1) and In A= 15.3 for 0.18 < alpha < 0.35 and E-A = 228 15 kJ mol(-1), In A approximate to 13 for alpha > 45%, respectively.
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Contributor : Jean-Louis Soubeyroux Connect in order to contact the contributor
Submitted on : Friday, July 6, 2012 - 3:02:18 PM
Last modification on : Tuesday, October 19, 2021 - 10:50:34 PM




T.K. Jondo, Philippe Galez, Jean-Louis Jorda, Joël Le Roy, J.C. Marty, et al.. The oxidation mechanisms of Cu54Ni45Mn1 (Constantan) tapes: Kinetic analysis. Thermochimica Acta, Elsevier, 2008, 475 (1-2), pp.44-52. ⟨10.1016/j.tca.2008.06.017⟩. ⟨hal-00715218⟩



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