Lithium disilicate and zirconia are the two most popular materials for aesthetic and dental prosthetic work; however, due to their limitations, a new material is being researched, namely zirconia-reinforced lithium disilicate, the surface of which is treated with different procedures to achieve the best possible surface properties. In this study, the surface of zirconia-reinforced lithium disilicate glass-ceramic was treated using different methods (conventional and laser) to determine the effects of the treatment procedures on the surface properties and surface roughness to achieve a higher strength of adhesion from the self-adhesive resin cement to zirconia-reinforced lithium disilicate. The treated surfaces were investigated using profilometry, X-ray diffraction and energy dispersive X-ray fluorescence. The results obtained were statistically evaluated. The results show that the surface roughness is highest for the samples treated with Er:YAG (erbium-doped yttrium aluminium garnet laser) and silanisation. Furthermore, the surface treatment procedures applied did not change the composition of the surface.

This paper deals with production of hard metal by powder metallurgy and its effect on the environment. Hard metal is a composite material that consists of tungsten carbide as the hard refractory phase and cobalt or nickel as the soft metal binder phase. It cannot be produced by classical casting technology. Owing to its excellent properties, such as high hardness, wear and heat resistance etc., hard metal can be applied in a variety of industrial fields. Powder metallurgy is a technology for production of a wide range of materials as net-shape products from a compacted and sintered powders mixture. In this paper the impact of all stages of hard metal production by powder metallurgy on the environment is analysed. The presented analysis shows that production of hard metal by powder metallurgy has a minimum effect on the environment.

In this paper, thermomechanical processing of niobium microalloyed steel was performed with the purpose of determining the interaction between niobium precipitates and dislocations, as well as determining the influence of the temperature of final deformation on the degree of precipitation and dislocation density. Two variants of thermomechanical processing with different final rolling temperatures were carried out. Samples were studied using electrochemical isolation with an atomic absorption spectrometer, transmission electron microscopy, X-ray diffraction analysis, and universal tensile testing with a thermographic camera. The results show that the increase in the density of dislocations before the onset of intense precipitation is insignificant because the recrystallization process takes place simultaneously. It increases with the onset of strain-induced precipitation. In this paper, it is shown that niobium precipitates determine the density of dislocations. The appearance of Lüders bands was noticed as a consequence of the interaction between niobium precipitates and dislocations during the subsequent cold deformation. In both variants of the industrial process performed on the cold deformed strip, Lüders bands appeared.

Titanium and titanium alloys have been widely used in medicine as implant materials for the last 50 years. The reason for this could be found in a unique combination of biocompatibility and strength of these alloys. The main advantage of titanium is the ability to bind to bone and grow into the implant. Due to the high cost of production, titanium is not used in large quantities, and therefore research are focused on finding new, more economical alloys. For these reasons, the aim of this paper is to analyze the effect of powder metallurgy process parameters in the production of titanium alloy containing 20% zirconium. Starting elemental powders were a ball milled and then compacted using the hydraulic press. Sintering process was performed under the different values of time and temperature. Starting powders were characterized using the scanning electron microscope. Porosity was analyzed using the light microscope. It was found that it could be decreased by increase in sintering temperature. Microhardness of polished sintered samples was determined by Vickers method. Results showed that higher microhardness values were obtained in samples sintered at higher temperature. Finally, results show that titanium-zirconium alloy produced by this route of powder metallurgy could be potentially used in a biomedicine.

Titanium based alloys are increasingly used in biomedicine due to their favourable properties. However, because of their high cost, new methods are being developed to produce more economical alloys. Therefore, in the framework of this work, Ti-20Nb alloy was produced by powder metallurgy. Namely, experimental alloy was prepared by mechanical alloying in a ball mill. The samples were singled out from the powder mixture and pressed on a hydraulic press. Sintering was carried out in a tube furnace in an argon atmosphere. Different processing parameters regarding the time and temperature of sintering were applied. Chemical homogeneity was analysed using the energy-dispersive spectrometry. Porosity was observed using the light microscope and microhardness was determined by Vickers method. The obtained results show that with a small correction of the applied technological parameters, in terms of time extension of mixing/mechanical alloying, it is possible to produce economically Ti-20Nb alloy having the properties suitable for biomedical application by using powder metallurgy technology.