T T-p sub / O2/ topologic analysis of phase relations in the system CaO-CrO-Cr sub 2 O sub 3 -SiO sub 2

Topologic analysis of phase relations in this system, involving divalent and trivalent Cr, was undertaken to determine the relative positions of isobaric invariant points and univariant lines in T-p sub / O2/ space. Liquidus phase relationships in equilibrium with metallic Cr, CO sub 2 -H sub 2 gas mixtures, and air were used to identify the univariant and invariant assemblages involving Cr sup 2 sup + and Cr sup 3 sup + . The T-p sub / O2/ grid was constructed using Schreinemakers rules for the disposition of univariant lines about an invariant point. The topological relationship between univariant lines and invariant points assisted in the interpretation of phase relationships over the T-p sub / O2/ regions that were not experimentally investigated.