Oxidación de alta temperatura del acero ferrítico 9Cr-1Mo modificado

this work describes the behavior shown by the isothermal oxidation of modified 9cr-1mo (astm a335-p91) steel by using the gravimetric technique in a multi-component oxidizing atmosphere (co2-co-o2-n2) in gas phase, at temperatures of 550, 650 and 750 °c and atmospheric pressure. the gravimetric technique was used discontinuously by means of gained weight per unit area vs. exposure time of the sample. this showed that, at temperatures of 550 and 750 °c, steel presents a parabolic kinetic behavior while, at 650 °c, it presents a mixed-linear kinetic behavior with experimental values of k [mg2/cm4h], for 550, 650 and 750 °c, were 0.0336, 0.04633 and 0.26335 respectively. the oxides formed at 550 and 750 °c had two types of oxide layers composed by a mixture of oxides of cr and fe. here, the amount of cr decreases from the inner to the outer layer, while the concentration of fe appears the other way around. at 650 °c, two oxide layers formed as well, but cr was not detected in the outer layer.