Phase Relationships in the System CaO—AI ₂ O ₃ —P ₂ O ₅

Abstract

Primary fields of crystallization in the system CaO‐Al 2 O 3 ‐P 2 O 5 at temperatures from 900° to 1600°C. were determined by the method of quenching. Three ternary eutectics were established: CaO·P 2 O 5 ‐Al 2 O 3 ·3P 2 O 5 ‐Al 2 O 3 ·P 2 O 5 , 2CaO·P 2 O 6 ‐CaO·P 2 O 5 ‐Al 2 O 3 ·P 2 O 5 , and 3CaO·P 2 O 6 ‐2CaO·P 2 O 5 ‐Al 2 O 3 ·P 2 O 5 . The rate of decomposition of Al 2 O 3 ·3P 2 O 5 was determined at several temperatures. The boundary was established between the field A1 2 O 3 ·P 2 O 5 , which covers about 35% of the ternary diagram, and the fields Al 2 O 3 ·3P 2 O 5 , 2CaO·P 2 O 5 , and CaO·P 2 O 5 . A portion of the Al 2 O 3 ·P 2 O 5 ‐3CaO·P 2 O 5 boundary also was established. A compound with the composition 2Al 2 O 3 ·3P 2 O 5 did not appear in the system. No calcium aluminum phosphates were found.