Abstract
Scales formed on Ni-Cr-base alloys and some practical heat-resisting alloys were investigated by X-ray diffraction method. The following results were obtained. (1) Alloying element, molybdenum, titanium and tungsten formed respectively NiOMoO3, NiOTiO2 and NiOWO3 in the scales of Ni-Cr-base alloys above 1, 000°C. (2) Cobalt and aluminum addition hindered the formation of these double oxides. (3) On Ni-Cr-base alloys containing titanium, formation of TiO2 was observed in higher content of titanium, and at higher temperature, (4) On Ni-Cr-base alloys containing niobium, CrNbO4 was formed above 1, 000°C, and NiONb2O5 was not formed. On Co-base alloys containing niobium, CrNbO4 was also formed.
