The join calcium monoaluminate-calcium fluoride

The system CaO-Al₂O₃-CaF₂ is important in cement and slag technology and in metallurgy. A section of this system, the pseudo-binary join CaO·Al₂O₃-CaF₂, has been studied and the phase diagram established. This join is of particular interest since CaO·Al₂O₃ is one of the main constituents of high alumina cement.Quenching in sealed platinum capsules followed by microscopic and X-ray examination was the principal method used. The only compound on the join is 3CaO·3Al₂O₃·CaF₂ which melts congruently at 1507±1.5° C and forms one eutectic with CaO·Al₂O₃ at 11% CaF₂ and 1498±5° C and another with CaF₂ at 97.5% CaF₂ and 1405±10° C. There is a wide zone of liquid immiscibility. The m.p. of CaF₂ was determined to be 1422±1° C.Attempts to use high temperature microscopy to study this system are described.