The results from two types of oxidation test are combined in this study. Table 1 shows the test matrix with the two approaches included. All the 100h tests and the test conducted at 650°C were performed using a thermogravimetric balance (TGA). The weight change during these tests was monitored continually and adjusted to accommodate buoyancy effects. All other tests were conducted in horizontal tube furnaces. For these latter tests, batches of specimens were placed in alumina boats and inserted into the furnaces at temperature. Intermittent weighing at room temperature was used to determine the oxidation kinetics. At selected time intervals, a specimen was removed from the batch for examination before the high temperature exposure continued for the remainder of the batch. Table 1 shows the time intervals chosen for examination. At 600°C one isothermal test, having an exposure time of 1000h, has been performed to date.
