N. Hussain et al., OXIDATION OF HIGH-TEMPERATURE ALLOYS (SUPERALLOYS) AT ELEVATED-TEMPERATURES IN AIR .2., Oxidation of metals, 43(3-4), 1995, pp. 363-378
In continuation of previous work, the oxidation behavior of three more
alloys, namely UHBA 25L, Sanicro 28, and Inconel 690, was studied at
high temperatures (600 to 1200 degrees C). The oxidation kinetics of U
HBA 25L and Sanicro 28 followed the parabolic-rare law at 800 and 1000
degrees C. At 600 degrees C oxidation rates were very low, while at 1
200 degrees C the parabolic-rate law was initially observed, followed
by ''breakaway.'' Both alloys suffered extensive spalling at all tempe
ratures, despite their high Cr contents of about 25% and 27%, respecti
vely This is attributed to significant amounts of Mn present. Sanicro
28, with higher Cr, suffered an early breakaway at 1200 degrees C beca
use of the presence of Mo, which forms a low-melting oxide. Inconel 69
0 showed mixed behavior at 600 and 800 degrees C, parabolic at 1000 de
grees C and cubic at 1200 degrees C. Inconel 690 and Incoloy 800H gave
the best overall performance for the range of temperature and exposur
e time under study. This may be ascribed to the absence of Mo, the pre
sence of small amounts of Ti and Al, and relatively small amount of Mn
in these alloys.