Oxidation behaviour of Ni–Cr based alloy containing Si during high temperature application in an oil burner

Abstract

In certain modern oil burners, the combustion reaction is started in a flame tube. In the combustion atmosphere, the tube material is exposed to high temperatures and temperature changes. Nickel–chromium alloys are used to meet the requirement of high oxidation resistance. The paper presents the results on the oxidation behaviour of the silicon containing alloy 603 exposed to a low NO_x burner at temperatures of 950 and 1000°C up to 2000 h. Beneath a chromia scale silica precipitates formed at the beginning of exposure, which grew laterally establishing a nearly continuous interlayer. The interlayer disintegrated during the continued exposure. A thinner chromia scale was observed for alloy 603 compared with the scales observed for aluminium containing nickel–chromium alloys. This was attributed to a pronounced scale spallation. After 1000 h at 1000°C catastrophic oxidation of alloy 603 occurred involving Mo oxide and internal chromium oxide.