PbO-SiO₂スラグ表面における固体SiO₂の局部溶損機構

抄録

Experiments show the following facts: Local corrosion of solid silica at the surface of liquid PbO-SiO₂ slag progresses in the area where the slag film, creeping up along the surface of the solid silica from bulk slag, moves actively by the Marangoni effect. Oxygen in the atmosphere does not affect the local corrosion. The local corrosion does not occur for the silica specimen which is wound tightly with platinum wire at the slag surface. The wire prevents the slag film from moving. Leading part of the local corrosion is in the portion where the specimen is washed vigorously with thin stag film which is rising up from the bulk slag. In this portion, the corrosion rate increases with increasing the film velocity.
The corrosion rate in the leading part is well described by the rate equation derived from the assumption that the rate is controlled by mass transport of dissolved SiO₂ in the slag film under the Marangoni flow of the film. The assumption is supported by the experiment made of the dissolution rate of rotating SiO₂ cylinder into the bulk slag.
The above results confirm that neither the volatile component in the slag nor oxygen in the atmosphere causes the local corrosion and the local corrosion results from the effective promotion of mass transport of the dissolved component from the specimen by the active Marangoni flow in the diffusion layer in the film.