Wettability of Solid Metals by Molten CaO-SiO2-Al2O3 Slag

The article presents results of the study of wetting of iron, nickel, and platinum substrates by molten CaO-SiO2-Al2O3 slag of near-eutectic composition by the sessile drop method in reducing atmosphere (oxygen partial pressure 10−20 to 10−18 atm). Terminal contact angles (after 240 minutes) for the CaO-SiO2-Al2O3 slag were as follows: for iron substrate, 55 ± 2 deg (1350 °C), 60 ± 2 deg (1390 °C), 44 ± 2 deg (1450 °C); for nickel, 59 ± 2 deg (1350 °C), 60 ± 2 deg (1390 °C); and for platinum, 15 ± 2 deg (1350 °C, 1390 °C, and 1450 °C). Under strongly reducing conditions in the graphite furnace, silica was reduced with dissolution of silicon into iron and nickel substrates, although the degree of SiO2 reduction from the slag was low. No silicon was detected in the platinum substrate. Wetting exhibited dynamic behavior. In nonisothermal continuous ramping and stepwise experiments, the contact angle decreased irrespective of changing temperature.