溶融(Fe<I><SUB>t</SUB></I>O-SiO<SUB>2</SUB>)系スラグ表面における透明石英ガラスの局部溶損現象の直接観察

Abstract

The present study has been conducted to clarify the local corrosion of solid oxide at the slag surface where the dissolution of solid oxide into the slag results in the reduction of its surface tension through direct observation of the local corrosion in SiO2(s)-(FetO-SiO2) slags. The results obtained are as follows: (1) The major part of the local corrosion zone occurs in the meniscus region of the slags which is called “slag film”. (2) The film has two types of characteristic movement. One is a rotational movement around the specimen surface on the initial stage of the local corrosion of the rod specimen; Another is an up and down movement of the whole slag film all at once along the specimen surface on the developed stage of the local corrosion of the rod specimen, and on the whole stage of the corrosion of the prism specimen. (3) Linear rate of corrosion, dL/dt, at the most corroded portion in the local corrosion zone increases with increasing temperature and FetO content. dL/dt at the corner of the prism specimen is \sqrt2 times as large as that at the plane. In a word, the cross section of the prism specimen keeps a square during the whole stage of the corrosion. For the rod specimen. dL/dt decreases with increasing initial diameter of the specimen. (4) A mechanism of the local corrosion for the present slag system has been estimated qualitatively from the standpoints of the Marangoni effect of the slag film induced by the dissolution of the specimen into the slag, and the wetting between the specimen and slag.