The experimental arrangement of a s

The experimental arrangement of a simple furnace with a gas feeder is schematically shown in Fig. 1. The furnace is composed of a ceramic tube, hot coils, refractory and a hatch. A few types of corrosive gases were supplied into the ceramic tube through a gas feeder from a flask. Five specimens (25 mm × 15 mm × 4 mm) were put in the middle of the furnace at a given high temperature, and taken out one by one for the five times of measurements and cooled. The specimens were not put back in the furnace. The weight gain and loss of the specimens was measured before and after a de-scale treatment. Surface observations on the tested samples by SEM and composition analyses of corrosion products collected from the films by X-ray diffraction (XRD) were performed.