C. Nastase

Thermal properties of ecological phosphate and silicate glasses

The present work deals with ecological phosphate and silicate glasses that belong to the oxide systems: Li2O-MgO-P2O5, Li2O-CaO-P2O5, Li2O-MgO-P2O5-Fe2O3; Li2O-CaO-P2O5-Fe2O3 and SiO2-R2O-R′O (R = Na, K; R′ = Mg, Ca), the last system contains certain amounts of ZrO2, ZnO, TiO2. These ecological glasses do not contain toxic substances as BaO, PbO, As2O3, As2O5, fluorine, CdS, CdSe and they have applications as regards the retention and counteracting action of the harmful compounds resulted from the nuclear plants. The replacement of MgO by CaO leads to an insignificant increasing of the thermal expansion index and a slight decreasing of the characteristic temperatures, except the softening point where the effect is opposite. Adding of iron oxide in the phosphate glass composition causes the increasing of characteristic temperatures and the decreasing of thermal expansion index, both in MgO and CaO-containing phosphate glasses. The ecological silicate glasses are used as opal glasses free of fluorine as well as for lead-free crystal glass (CFP) where BaO and PbO are replaced by non-toxic oxides as K2O, MgO, ZrO2, and TiO2. The paper presents different glass compositions and the technological parameters to prepare the ecological glass samples. Both ecological phosphate and silicate glasses have been characterized as regards the characteristic temperatures (vitreous transition point, low and high annealing points, softening point) and the thermal expansion coefficient. This study presents the changes of the thermal parameters when CaO replaces MgO in phosphate glass samples and the role of iron oxide in the vitreous network. In the case of silicate glasses, the viscosity and wetting angle dependency of temperature are presented. The elemental analysis of the ecological glasses was made by XPS (X-ray photoelectron spectroscopy) which also put in evidence the iron species from the vitreous network.

CsHSO4/Nanooxide Polymer Membranes for Fuel Cell

Composite solid acid/nanooxide polymer membranes with good electrical behaviour can be obtained by thermocentrifugal field processing. The supporting polymer matrix is designed to embed solid acids or strong solid acids/nanooxides making it appropriate for proton conducting composite membranes. Nanocomposites CsHSO4-YSZ/PAN membranes were investigated by Raman, FT-IR and SEM techniques. The dependence of the electrical conductivity on temperature is evaluated.

High-quality carbon nanotubes production using plasma-chemistry deposition method

Catalyst assisted chemical vapor deposition(CVD)is one of the most viable routes in production of carbon nanotubes(CNTs), but purification and deposition in oriented position still remain an open question. This contribution presents a method to deposit high-quality nanotubes, using RF-plasma assisted CVD and catalytic decomposition of a ferrocene-toluene mixture in a quartz tube reactor. The most important phenomena that have been encountered are that the iron released from ferrocene play catalyst role only on a characteristic length, being removed after that by plasma etching. Raman spectroscopy and Transmission Electron Microscopy(TEM)characterized the obtained carbon structures.

Synthesis and Characterization of Carbon Supported Pd and PtPd Catalysts for DMFCs

Carbon supported Pd and PtPd catalysts were prepared by chemical reduction of metal precursors with sodium borohydride. Multi-wall carbon nanotubes (MWNTs) were used as carbon support. The composition of prepared catalysts was given by EDX technique. Cyclic voltammetry (CV) measurements were used to evaluate the electrocatalytic activities for methanol electrooxidation after their immobilization onto carbon paper.