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To determine the effect of boric oxide upon-the melting points and temperatures of formation of the calcium silicates contained in portland cement, namely, dicalcium silicate and tricalcium silicate, a study of the ternary system CaO-B~O3-SiO~ is in progress. The binary system CaO-B~03 has already been investigated by E. T. Carlson (B. S. J. Rsearch, 9, 825 (1932); RP5Io), and that of CaO-SiO~ by Shepherd, Rankin, and Wright (Am. J. Sci., (4) 22, 265 (19o6)). In working out the fields of 3CaO. SiO~(C3S) and of 2CaO. SiO2. (C2S) in the ternary system it was found necessary to extend the investigation to the adjacent fields of 3CaO.2SiO2(C8S2) and of CaO. SiO2(CS) as well as to the fields of the calcium . borates, 3CaO. B~O3(CsB), 2CaO. B203(C2B), and CaO. B~O3-(CB). This more complete study is of significance not only with respect to cement chemistry but in relation to the constitution of enamels and ceramic glazes. The portion of the system lower in lime and higher in silica and boric oxide has a bearing upon the constitution of borosilicate glasses.
The following binary or pseudo-binary systems belonging to the ternary system have been completely or partially worked out by heating curves and quenchings upon I I 4 different compositions: CB-CS, CB-C3S2, CB-C~S, CB-CsS, C~B-C2S, C2B-CsS, and C3B-C2S. Melts containing 44.3 per cent. C~B, 55.7 per cent. C3S, or 58.o per cent. CaB, 42.o per cent. C2S form the ternary compound 5CaO. B203.SiO2-(CsBS). Determinations of the primary phases and melting points of the various compositions have indicated approximately the boundary curves of the fields of C2S, CaB, C2B and partially the limits of the fields of CS, CsBS, and CB.
It has been found that dicalcium silicate takes up considerable quantities of boric oxide (added as monocalcium borate) in solid solution by which the alpha-beta inversion temperature is lowered as much as 13 °0 .
📜 SIMILAR VOLUMES
## Tobermorite formation was studied in the system C; C3S-S-A-N-H in suspension at 180°C. Tobermorites forw~d were ~vestigated by the molybdate method and by ='AI and ~Si MAS NMR with a purpose to evaluate the influence of aluminum and sodium ions on the changes of secondary arrangements of basic
The individual subsystems of the basic five component oxide system CaO-SiO2-AI203-Fe203-SO 3 are analysed for their subsolidus phase relationship. The study is confined to the portion of the system in which C2S, the key mineralogical component of belite clinker is present. As a result eighteen equil