High temperature oxidation of centrifugally cast heat-resistant alloys

AbstractThe oxidation behaviour of three novel, heat-resistant alloys has recently been investigated at 650, 750, and 850°C. The alloys, namely KHR35C HiSi (HP), KHR45A LC (35Cr-45Ni), and UCX, were exposed to static air for periods of 100 and 1000 hours. The alloy KHR35C HiSi is an iron-based alloy whereas the others are nickel-based, and all had been manufactured via centrifugal casting. Visual and metallographic examination (SEM/EDX, XRD) and weight change measurements were carried out in order to characterise the nature and morphology of the resultant oxides. Different oxides including those of chromium, silicon, nickel, iron, and manganese-containing spinels were detected on the alloy surfaces. Further oxide growth and thus more continuous, adherent and thicker layers were observed to have occurred as a consequence of increasing the exposure time, temperature or both. The alloys, however, did not seem to have formed a completely continuous scale, especially at 650°C, even after 1000 hours of constant...