VI 2017

Preliminary studies on the use of fine fractions of chalcedonit in ceramic technologies
Chalcedonite is a unique siliceous material extracted from the Teofilów deposit in Inowłódz, Poland. Specific properties of the material, such as a high content of amorphous silicon dioxide and high porosity (up to 25%) promote an incorporation of the chromophore component (Fe2O3) particles into the pores and their “enclosure” in the SiO2 structure in the process of high-temperature sintering. The test method used for verification and quantitative evaluation of Fe2O3 incorporation into the SiO2 matrix is hot leaching of the ferric component from the sinter structure in an acidic environment. The obtained coloured sinter of a composite character displays the properties of both components simultaneously. Like quartz, it is resistant to chemical influences from the environment at high temperatures; also, it is red-brown due to the colour of the hematite particles. The colouration of the ceramic material (floor tile mass) expressed with the parameters: L*. a*, b*, proves colour stability of the sinter employed as a pigment. The presented study results of a preliminary nature promise good effects of hematite occlusion in the SiO2 matrix, also in largescale processes.
prof. ICiMB, Cecylia Dziubak Ph.D. Eng., Paulina Tymowicz-Gzyb M.Sc.

Ceramic materials in dentistry
Over the last 20 years there has been a rapid development in dental prosthetics, which can be observed in the improvements in the mechanical and aesthetic properties of the materials introduced, as well as in their processing technology. This improvement can be linked with a desire to create prosthetic restorations meeting the ever-increasing aesthetic
requirements of patients; and as a consequence, materials and methods used, although proven and very effective, are increasingly being replaced by new technologies. The article presents the classification of ceramic materials used in restorative dentistry, taking into account selected aspects. Differences between commonly used metal-ceramic restorations and relatively new all-ceramic ones were noted. Much attention was paid to materials based on zirconium dioxide, which due to their unique aesthetic and mechanical properties have become increasingly popular in recent years and have begun to replace silicate ceramics. Use of CAD/CAM systems as an alternative to time-consuming and labor-intensive traditional restoratives, was also discussed. Weaknesses of these systems, which still need to be improved, were also indicated.
Michał Wydra D.D.S, Iwona Grelowska M.Sc. Eng.

Studies of the properties of alumina and aluminosilicate slurries for ceramic shell moulds
The paper presents results properties of alumina and aluminosilicate slurries dedicated to the first layer and construction layers of shell molds, respectively. The influence of the solid phase content on the parameters of the slurries was determined. Particle size distribution was determined with use of the advanced laser particle size analyzer Horiba LA-950 (LALLS technique). To characterize morphology of the powders and binder scanning electron microscopy (SEM and STEM) observations were performed. The slurries were prepared in a mechanical mixer. The experiment was based on a daily plate weight tests and pH, Zahn cup (4 mm diameter) viscosity and dynamic viscosity by rheometer with a shear rate range of 1–100–1 1/s measurements that are fundamental for investment casting industry. Adhesion of the examined mass was determined by the plate immersion (dimensions: 75×75 mm) in a slurry and estimation its weight of 75.46 g. The slurry dipping was controlled during 180 seconds with results notation every 15 seconds. The obtained results proved opportunity of their application for the investment casting and foundry, being prospective issue for future fabrication of shell moulds.
Paweł Wiśniewski Ph.D.

Analysis of the properties of glasses of multilayer coatings based on TiO2 exposed to UV radiation and salt fog.
This article discusses the role of coatings used in building glazing and the requirements that must be met according to standards in force, with particular regard to self-cleaning coatings. The chemical composition and thickness of the coating were determined using an electron microscope and the light and energy parameters of the self-cleaning glass were determined. The degree of degradation of these glass surfaces was determined by exposure to aging agents (UV radiation and salt mists) and the effects of these factors on light and energy properties were determined. A final analysis of the results obtained.
Anna Balon-Wróbel M.Sc., Agnieszka Marczewska