| 摘要 |
PURPOSE:To obtain a molten metal surface protective material for continuous casting of steel having less surface defects and internal defects by minimizing alkali metallic ions and compounding the specific property adjusting agent for the molten metal surface protective material. CONSTITUTION:The molten metal surface protective material is powder or granules made by mixing, calcining or melting raw materials or the combination thereof and has the range of 0.6-1.3 basicity (CaO/SiO2), 25-40wt% CaO, 25- 40wt% SiO2, 3-15wt% F<->, 0.1-10wt% Al2O3, 1.0-20wt% MgO and <5% Na<+>. Said material contains 0.1-20% a combination of 1 or 2 kinds of AlF3 and B<+> and consists of <=10% carbon powder as a melting rate adjusting agent. The material has small hygroscopicity. The change in the properties of said material is small even if the Al2O3 therein is thickened. The material has also the high power to absorb Al2O3. |
