Accession Number : AD0600744

Title :   STUDIES RELATED TO THE CRYSTALLIZATION OF GLASSES: CONTROLLED PHASE SEPARATION DUE TO METASTABLE LIQUID IMMISCIBILITY IN SIMPLE SILICATE SYSTEMS.

Descriptive Note : Technical rept. no. 2

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB

Personal Author(s) : Phillips,Bert ; Roy,Rustum

Report Date : 15 MAY 1964

Pagination or Media Count : 21

Abstract : The tendency to separate metastably of compositions close to but outside of stable liquid immiscibility regions was studied for various simple silicate systems such as BaO-B2O3-SiO2, PbO-B2O3-SiO2, CaO-MgO-SiO2, and CaO-TiO2-SiO2. Another system, namely Na2O-B2O3-SiO2, where stable liquid immiscibility does not occur, but from which compositions are known to yield metastable separation was also studied as a reference. Small glass specimens were heat treated over a range of temperatures to determine the temperature range of metastable separation. Rods of similar composition were drawn and heat treated in the determined temperature range to develop phase separation. The products were studied by light and electron micrography, and x-ray diffraction. Phase separation due to metastable liquid immiscibility was affected in at least one composition from each system studied, whereas other compositions nearby did not produce this effect. Small amounts of other oxides could be added without inhibiting separation in those basic compositions where it occurred. The phase separation which developed caused no significant change in the transverse strength of these glasses. (Author)

Descriptors :   (*GLASS, CRYSTALLIZATION), (*SILICATES, PHASE STUDIES), SEPARATION, HEAT TREATMENT, X RAY DIFFRACTION, OXIDES, NUCLEATION, CERAMIC MATERIALS

Distribution Statement : APPROVED FOR PUBLIC RELEASE