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.
Single particle impact tests on block specimens (45 mm× 45 mm× 100 mm) in high temperature corrosive environments were conducted with a compact gas gun schematically shown in Fig. 2.
Glass beads with 2, 3 and 5 mm in diameter were impacted on the specimens with corrosion product or oxide films at 50 and 70 ms−1.
The specimen surfaces were observed with a video camera connected to a computer.
The indented and spalled and detached areas of the films were measured by using image processing.
Impact tests with the same particle size were performed on metal surfaces at room temperature to obtain height distributions of piling-up surfaces around the indentations.
Commercial mild steel was used as a standard material in this study.
The high temperature corrosive environments were wet air, water steam and water steam with hydrogen chloride of 0.5 and 10 vol.% as average volume percentages during tests.
The two corrosive gases were supplied from the flask as boiling 10 and 20 wt.% hydrochloric acid solutions respectively.
The tested temperatures were 673, 773 and 873 K in the corrosion/oxidation tests and 873 K only in the single particle impact tests.