Nataliia Gorodylova

Effect of the synthesis conditions on the formation of MgSrP2O7 and its characterisation for pigmentary application

In present research, we examined MgSrP2O7 as a new pigment with focus on its application as a corrosion inhibitor. The influence of the synthesis’ conditions on the product properties was examined. Samples were obtained by solid-state reaction and various homogenisation methods of initial components were employed (hand-milling, wet (ethanol/acetone) ball-milling and coprecipitation). Thermal behaviour of the reaction mixtures or dried coprecipitate was investigated using differential thermal and thermo-gravimetric analyses. Obtained samples were characterised with X-ray diffraction analysis, scanning electron microscopy and IR spectroscopy. Focusing on pigmentary application, specific properties of the samples were evaluated, such as thermal stability, mean particle size values and colour parameters, and also preliminary anticorrosion tests have been performed. Based on obtained results, MgSrP2O7 could be considered as a perspective corrosion inhibitor and homogenisation via coprecipitation can be rated as the best method of preparation of this composition, which provides the best thermal stability, the lowest particle size, the best homogeneity and the most promising corrosion inhibition characteristics (pH and ρ of the pigment aqua suspension) for the final product.

Thermal stability and colour properties of CuZr4(PO4)6

In present work, CuZr4(PO4)6, which is a complex phosphate of NASICON family, has been characterised as ceramic pigment. To this purpose, its thermal stability, colour properties and some other important pigment characteristics were studied. In order to obtain pure phase ceramic powder of CuZr4(PO4)6, several synthesis approaches were attempted. The thermal transformations in the reaction mixtures were investigated by DTA-TG and XRD analysis. Thermal stability of the obtained products was studied using heating microscopy, DTA-TG and XRD analysis. Colouring performance and lightfastness of CuZr4(PO4)6 were tested within commercial ceramic glazes, and its colour in powder and glaze is described by means of CIELAB and CIELCh systems. It is shown that CuZr4(PO4)6 ceramic powder has sufficient thermal stability and attractive colouring properties to be used as ceramic pigment.

Thermal transformation of layered zinc hydroxide chloride

Zinc hydroxide chloride, Zn5(OH)8Cl2·H2O, belongs to a special group of layered materials which are used in a wide variety of commercial applications. During the heating, Zn5(OH)8Cl2·H2O undergoes a complex transformation which involves several overlapping stages and highly depends on the experimental conditions. Although it is well established that the thermal transformation of Zn5(OH)8Cl2·H2O leads to the formation of ZnO as final product, there is still no generally accepted mechanism explaining the intermediate stages of this process. This review provides a summary of the studies devoted to this topic complemented by critical data assessment and generalisation of the established information. We hope that the review conveys to the reader state of the art of this problem and provides baseline knowledge required for complete understanding of thermal behaviour of this material.

Impact of particle size reduction on glaze-melting behaviour

The effect of milling on thermal behaviour of two types of industrial ceramic glazes was investigated by heating microscopy. The Vogel–Fulcher–Tamman equation was used for viscosity calculation of the glaze samples, and the impact of particle size reduction on calculated data has been analysed. The employed model provides a good fit to the general tendencies of viscosity change during melting and can be applied for a comparative description of glaze-melting behaviour. Observed correlations between the viscosity, the contact angle, milling time, glazing temperature and the specular reflection of the glazed tiles help to reveal the optimal physical characteristics for glaze manufacturing and to achieve the desired gloss and smoothness of glazed surface. On its turn, variation of particle size distribution highly affects thermal behaviour of ceramic glazes, and thus, the milling procedure provides the possibility of manipulation of glaze-melting behaviour during heating and allows to change the manufacturing heating cycle when required.

A comparative study of the influence of the method of synthesis of intermediate products in the preparation of CoNd2W2O10 and MnNd2W2O10 and their color properties in ceramic glazes

The compounds CoNd2W2O10 and MnNd2W2O10 were prepared by solid state reaction between CoWO4, resp. MnWO4 and Nd2WO6. Intermediates were prepared in laboratory by a solid state reaction and by a co-precipitation reaction. The new single-phase compounds CoNd2W2O10 and MnNd2W2O10 were prepared only from intermediates prepared by solid state reaction, as in second case the morphology of particles is inappropriate and during the reaction an unknown phase (Nd–W–O) is formed. To describe the processes during thermal reactions, the DTA/TG were used. CoNd2W2O10 and MnNd2W2O10 belong to the orthorhombic crystallographic system, their diffraction pattern were indexed. The new compounds were tested as inorganic pigments. Application of the prepared compounds in ceramic glazes did not provide technological interesting results. The reason is probably the low thermal stability of the prepared compounds CoNd2W2O10 and MnNd2W2O10. In particle form CoNd2W2O10 has blue color and MnNd2W2O10 has brown color.

High Energy Milling of Zirconia: A Systematic Critical Review on the Phase Transformation

The phase transformation of zirconia from monoclinic to tetragonal polymorph at room temperature under mechanical processing has been a subject of a great interest due to technological importance of this material. Mechanism of this transformation has been widely investigated and plenty of explanation theories of zirconia stabilisation have been developed as well. This article critically reviews the systematic development regarding this transformation under mechanical processing and includes the summarised results of key-publications on this topic.