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.

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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.

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