Construction of a state diagram of the naphthalene-diphenyl-dibenzyl triple system with overcooling

Abstract

On the basis of binary diagrams of states naphthalene - dibenzyl, diphenyl-dibenzyl and naphthalene- dibenzyl with metastable regions concerning liquidus lines, there was constructed the triple diagram of states naphthalene-diphenyl-dibenzyl with precrystallisation supercoolings in expanded and assembled form. Parameters of ternary eutectics have been determined from the condition of phase equilibrium at liquid-solid boundary considering activity coefficients of corresponding components in approximation of ideal solutions. It has been established, that eutectic composition is 21,9 wt.% naphthalene + 33,0 wt.% biphenyl + 45,1 wt.% dibenzyl, and eutectic temperature is 290 ± 2 K. It is determined that triple eutectic alloy of naphthalene-diphenyl-dibenzyl system crystallizes practically without overcooling (~ 1-1,5 K) and can be recommended for its use as a heat-accumulating material based on phase transition phenomenon of melting-crystallization type.