Grzegorz Garzel

Electromotive force measurements in liquid Ag-In-Pd lead-free alloys

Abstract Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme: kanthal/rhenium, Ag-In-Pd, In 2 O 3 | YSZ | Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for X PD up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for furnace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equations. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.

Phase equilibria in the CoO-SiO2 system

The emf method was employed to determine thermodynamic properties of cobalt orthosilicate, taking into account two different crystallographic forms of silica: amorphous and quartz. Results were then compared to available literature data and used along with other experimental information of the system to evaluate a thermodynamic description by the CALPHAD method.

Microstructure and Thermal Analysis of As-Cast Ag-Bi-Ni alloys

The calculated liquidus projection of the Ag-Bi-Ni ternary system has been experimentally examined. Alloys were prepared by induction melting, and their microstructure studied by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. Of the primary solidification phases, (Ni) solidifies over the largest concentration range, although it was found to be narrower than calculated. The range in which Bi3Ni is the primary solidification phase was found to be broader than calculated. Also, the liquid miscibility gap is broader than predicted from assessed thermodynamic parameters. Differential thermal analysis was used to study temperatures of phase transitions of as-cast alloys, and recorded temperatures of melting of Bi3Ni and BiNi phases in ternary alloys agree well with those calculated.