Due to good properties, which meet the requirements for use as biomaterials, titanium and titanium alloys have been increasingly used as dental implants. Until recently, dental titanium alloys were produced by casting. Since this process does not meet the terms of economy and efficiency, the production of titanium implants by powder metallurgy are very promising. Therefore, in this work titanium alloy with addition of 10 at. % zirconium is prepared by powder metallurgy with the goal of obtaining the best producing conditions, which would result in the titanium alloy of the adequate properties for use as dental implants. High values of green densities were achieved even only by uniaxial pressing. Further, sintering temperature of 1673 K resulted in the alloy of the highest sintered density and microhardness. The results of this investigation revealed the processing parameters applicable for the production of titanium-zirconium dental implants by powder metallurgy.

MIcrostructural and equIlIbrIuM adsorptIon study of the systeM of waste foundry MoldIng sand/cu (II) IonsThis paper deals with the waste foundry molding sand which originally comes from the casting production. Adsorption of Cu (II) ions on the waste foundry molding sand was studied. Experimental data were processed using adsorption isotherms. obtained results show that the experimental data are best described by the Langmuir isotherm. The following adsorption capacities are obtained: 7.153 mg/g to 293 k, 8.403 mg/g at 333 k and 9.208 mg/g at 343 k. The kinetics and thermodynamics of the process were analysed. The obtained results indicate that the adsorption process takes place according to the pseudo second order kinetic model with the following constants: 0.438 g/mg min at 293 k, 0.550 g/mg min at 333 k and 1.872 g/ mg min at 343 K. The following values of ΔG° were obtained: -95.49 j/mol at 293 k, -736.99 j/mol at 333 k and -1183.46 J/mol at 343 K. The value of ΔH° is -4.16 kJ/mol and the value of ΔS° is 15.17 j/molk. These results were confirmed by microscopic examinations. The results indicate that the adsorption process of Cu (II) ions on waste foundry molding sand is possible. Results of microscopic examinations show the homogeneity of the surface, which is proof of the chemisorption. Cu (II) ions on the surface of the waste foundry molding sand were detected after adsorption by EDS analysis, which proves the existence of the adsorption process.

The effect of pig iron, steel scrap and ductile iron returns content in metallic charge on the nucleation potential and metallurgical quality of the base iron and ductile iron and the final microstructure and tensile properties of ductile iron is analyzed in this paper. The obtained results confirm the beneficial effect of pig iron addition on the nucleation potential of base and ductile iron producing an increase in nodule count and a decrease in chilling tendency of both base and ductile iron. The steel scrap has a price much more convenient than pig iron, but the use of high percentage of steel scrap in the charge was limited due to decrease in nucleation potential and increase of chilling tendency. Ductile iron returns also contributed to lower nucleation. Preconditioning did not completely correct the negative effect of high percentage of steel scrap in metallic charge. The results showed that the base iron must have had enough nucleation potential in order to obtain efficient inoculation. It was found that the tensile properties of ductile iron, especially the elongation, increased with the increase of the percentage of pig iron in metallic charge, due to increase of nodularity and nodule count. K e y w o r d s : ductile iron, metallic charge materials, metallurgical quality, nucleation potential, thermal analysis

In this paper, the adsorption properties of two metallurgical wastes (slag and anode dust) and two municipal wastes (eggshells and coffee grounds) were described. Acetic acid was used as the adsorbate Adsorption kinetic was monitored during the adsorption process. The obtained results showed that all tested waste materials can be used as potential cheap adsorbents. Adsorption took place relatively quickly. Equilibrium was reached in 15 minutes, and the adsorption kinetics followed the pseudo-first-order reactions, i.e., can be described by the Lagergren model. All qe values calculated using Ho's model have a negative sign. That indicates that the Ho model is not suitable for describing the kinetics of the tested adsorption systems.

No abstract