1993 Volume 33 Issue 1 Pages 133-139
Oxygen transfer rates, P, through molten NiO-CaO-SiO2, ZnO-CaO-SiO2 and NiO-ZnO-CaO-SiO2 systems were observed by using a molten thin film penetration method developed by the author. Observation temperature were about 1450, 1500 and 1550°C.
Magnitudes of the transfer rate are 1 to 5 times 10-8 mol O2·cm-1·s-1, the same magnitude as that in the iron oxide-CaO-SiO2 system measured previously. In the system containing NiO, the greater NiO content, the higher the oxygen transfer rate. In the system containing ZnO, in contrast, the greater the ZnO content, the higher the oxygen transfer rate in the case of less than 20 mol% ZnO and the lower the oxygen transfer rate in the case of more than 20 mol% ZnO.
Effects of constituents on oxygen transfer rate, P, in mol O2·cm-1·s-1 are empirically expressed as follows:
A system less than 12.5 mol% NiO:
P=3.15×10-9(mol%NiO)
A system less than 35 mol% ZnO:
P=–8.5×10-11(mol%ZnO-22)2+4.2×10-8
Temperature dependencies of the oxygen transfer rates are:
7.5mol%NiO-46.3mol%CaO-46.3mol%SiO2;
P=3.51×10-2exp(-25.3×103/T)
10mol%ZnO-45mol%CaO-45mol%SiO2;
P=3.24×10-2exp(-25.3×103/T)
20mol%ZnO-40mol%CaO-40mol%SiO2;
P=6.39×10-2exp(-25.3×103/T)
30mol%ZnO-35mol%CaO-35mol%SiO2;
P=4.96×10-2exp(-25.3×103/T)
It is speculated that NiO and ZnO act as p- and n-type semiconductors, respectively, on the basis of the discussion of the dependency of the transfer rate on oxygen partial pressure at the surface of molten oxide.
