Abstract
With the same reason of the previous report (part III), the author has studied the reactions between 5CaO⋅3Al2O3 and 2CaO⋅Fe2O3 at high temperatures by microscopic and X ray methods.
The samples were made by heating, at 1300, 1350°C and over, 16 mixtures of 5CaO⋅3Al2O3 and 2CaO⋅Fe2O3 with various molar ratios as shown in the next table.
Table 1. Molar ratios of 5CaO⋅3Al2O3 and 2CaO⋅Fe2O3 in the mixtures
The experimental results are as follows:
(1) 2CaO⋅Fe2O3 and 5CaO⋅3Al2O3 make each other solid solutions of limited miscibility.
(2) The miscibility in these solid solutions increases with the rise of temperature.
(3) The samples of No. 13-19 which were made by firing at 1350°C and those of No. 13-17 made at 1300°C belong to the same solid solution series, and their X ray diffraction patterns are of the same type with that of 2CaO⋅Fe2O3. That is to say, a certain mol of 5CaO⋅3Al2O3 seems to be miscible in the lattice of 2CaO⋅Fe2O3, The limited miscibility is 0.5mol of 5CaO⋅3Al2O3 to 1mol of 2CaO⋅Fe2O3.
Reversively, a small amount of 2CaO⋅Fe2O3 is miscible in 5CaO⋅3Al2O3, and makes a solid solution having a diffraction pattern of 5CaO⋅3Al2O3 type.
(4) In the fired samples of No. 20-28 or so, two solid solutions of 2CaO⋅Fe2O3 and 5CaO⋅3Al2O3 types co-exist.
(5) These two solid soiutions seem to have an eutectic point microscopically.
(6) The lattice spacing of the samples (No. 18-20) having the greatest miscibility in the 2CaO⋅Fe2O3 type solid solutions is, on the whole, the same with that of the sample of the molar ratio of 2CaO⋅Fe2O3:3CaO⋅Al2O3=1.00:0.25-the molar ratio of the utmost limit to which 3CaO⋅Al2O3 is miseible into 2CaO⋅Fe2O3 in its original form-and also the same with that of the fired sample of 5CaO:Al2O3:Fe2O3, but never reaches to that of the fired sample of 4CaO:Al2O3:Fe2O3.
