The system lime-boric oxide-silica

Abstract

The equilibrium diagram for the syst em CaO-B20 a-Si02, constructed from data on 200 t ernary compositions, is presented. The portion of the diagram immediately adjacent to the binary system B20 a-Si02 is incomplete. A unique feature of the system is the appearance of an area of liquid immiscibility extending across the diagram from the lime-silica side to the lime-boric oxide side and crossing the fields of silica, monocalcium borate, and calcium diborate. A newly established ternary compound, 5CaO.B20 a.Si02, melts congruently at 1,419 0 C. Tricalcium silicate does not appear at the liquidus in the ternary system. Dicalcium silicate forms partial solid solutions with calcium borates whereby the 0I.-{3 inversion temperature is lowered by a maximum of 190 0 C. CONTENTS I. Introduction _______________________________________________ _ II. General procedure __________________________________________ _ l. Preparation and analysis of mixtures ___ __ ________ ___ ____ _ 2. Apparatus and methods _______________________________ _ III. The stability fields __________________________________________ _ l. CaO.Si0 2 _________________ ___________ _ _______________ _ 2. 3CaO.2Si0