AUTOCORRELATION TREATMENT OF THERMOGRAVIMETRIC DATA WITH THE COCHRANE-ORCUTT METHOD

• Main Authors: V. F. C. LINS, E. M. PAULA e SILVA
• Format: Article
• Language: English
• Published: Brazilian Society of Chemical Engineering 1997-06-01
• Series: Brazilian Journal of Chemical Engineering
• Subjects: Fe-Mn-Al-Si-C alloy; oxidation kinetics; thermal analysis
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66321997000200010

Abstract - The interaction of an Fe-Mn-Al-Si-C alloy with the environment was evaluated. The alloy showed good resistance to air and oxygen oxidation, especially at temperatures of 600 and 700º C for air oxidation and at 600ºC in oxygen atmosphere. Oxidation rates for pure oxygen were lower than those measured for air. Due to autocorrelation identified in the results, it was impossible to employ the usual procedures of Regression Analysis. Kinetic data were then analyzed by the statistical method of Cochrane and Orcutt. A parabolic kinetic behavior was observed for the Fe-Mn-Al-Si-C alloy oxidation process in the air at temperatures of 600, 700 and 800ºC and in an oxygen atmosphere at 900ºC. On the other hand, the TGA results for oxygen oxidation at 600 and 700ºC and for air oxidation at 900ºC adjusted well to the linear kinetic curve. Finally, the cubic kinetic curve was selected to represent the oxidation of the alloy in oxygen at 800ºC.