GLASS-FORMATION IN THE SYSTEM B2O3-PBO-CUO

The ternary system B2O3-PbO-CuO was investigated to determine the exte nt of the glass forming region, as multicomponent glasses based on thi s system find many industrial applications particularly as solder mate rials. More than 100 compositions covering a major part of the system were melted in platinum crucibles in electric furnaces. The samples we re annealed after forming. Only standard techniques were used. XRD was used to differentiate between glass partially crystalline and entirel y crystalline compositions as some compositions were opaque or intense ly coloured. Three principal regions on the ternary diagram were ident ified: (1) A wide glass forming region was observed taking nearly the form of a triangle the base of which was the glass forming region in t he binary B2O3-CuO sub-system. The base extends toward the apex which lies at the composition containing 50B(2)O(3).5PbO.45CuO (mol%); (2) A ll compositions prepared from the binary B2O3-CuO sub-system and those of the ternary system, outside the glass forming region, which contai n at least 20 mol% B2O3 were partially crystalline; and (3) All compos itions prepared from the binary PbO-CuO subsystem as well as those fro m the ternary system which contain less than 20 mol% B2O3 were entirel y crystalline. The results also indicated that the crucibles used for melting cart have a significant effect on the glass forming tendency o f some of the compositions. The main visual and XRD characteristics of compositions belonging to each region were considered.