Tsvetan Dimitrov

Tsvetan Dimitrov
University of Ruse Angel Kanchev | UR · Branch Razgrad

Doctor of Engineering

About

32
Publications
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48
Citations
Introduction
Tsvetan Dimitrov currently works at the Branch Razgrad, University of Ruse Angel Kanchev. Their most recent publication is 'SYNTHESIS AND STUDY OF Ni-DOPED WILLEMITE CERAMIC PIGMENTS 1'.

Publications

Publications (32)
Article
Ceramic pigments in the system CaO–CoO – MgO–2SiO2 were synthesized through solid-state high temperature sintering at 1000, 1100 and 1200 °C. The starting compositions were determined from the stoichiometric mineral diopside, following the expression CaO.xCoO.(1-x)MgO.2SiO2, where x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.5, 0.7 and 0.9. The effect...
Article
The article reports the mineralogical composition, structural features and changes in color parameters of iron-containing diopside pigments. The source of SiO2 in these pigments was SiO2nH2O with a particle size in the range of 2–7 m, which is much more reactive than conventionally used quartz sand. A series of ceramic pigments on the basis of st...
Article
Full-text available
Abstract. The object of the present study is investigation of possibility of obtaining zircon ceramic pigments by utilising a widespread bio-waste – rice husk. Rice husk ash was used as a source of SiO2. The preparation of high temperature ceramic pigments using colourless stable crystal carcasses turns out to be quite suitable method in the case o...
Article
Full-text available
Zirconium ceramic pigments with basic zircon phase-ZrO2.SiO2 were synthesized by solid phase sintering of pure oxides: ZrO2, SiO2.nH2O, and the following elements were added as colorants: V, Fe, Cr, Co and Mn. NH4Cl was used as a mineralizer. The pigments were synthesized at three final firing temperatures: 1000, 1100 and 1200 ° C. The color charac...
Article
Full-text available
This work focuses on the syntheses of willemite ceramic pigments doped with cobalt and nickel ions (Co ²⁺ , Ni ²⁺ ). The pigments were prepared by the sol−gel process. The phase formation has been studied by X - ray diffraction analysis. The results showed that phase composition depends on sintering temperature, isothermal retention period as well...
Article
Full-text available
The synthesis of ferrum-willemite ceramic pigments in the system xFeO(2-x)ZnOSiO 2 (where x=0.125-1.00) was investigated in this work. The results of colorimetric measurements (in the system CIEL * a * b *) showed that the concentration of iron(II) oxide in the composition of 0.25 mol is sufficient for preparation of ceramic pigments of red-brown...
Article
Full-text available
The paper covers the study of the opportunity to synthesize ferrum-willemite ceramic pigments in the system xFeO•(2-x)ZnO•SiO2, where x = 0.125 – 1.00. Effective role of hydrate of silicon(IV) oxide introduced as a quartz containing component of experimental pigments is shown. It allows reducing the temperature of their synthesis to 900–1000°С. Ris...
Conference Paper
Full-text available
This work focuses on the syntheses of colored willemite ceramic pigments. The pigments were prepared by solid phase sintering technology. The paper reports experiments carried out on the synthesis of willemite pigments doped with ions of transition elements as well as iron, manganese and vanadium. The sintering temperatures were between 900 and 1 2...
Article
Full-text available
The possibility of synthesizing manganese-willemite ceramic pigments in the system xMnO · (2 – x)ZnO · SiO2 (x = 0.125; 0.250; 0.375; 0.500; 0.625; 0.750; 0.875 and 1.00) was studied. Manganese-willemite ceramic pigments were synthesized at 800 – 1200°C. The obtained pigments were investigated by means of x-ray phase analysis, electron paramagnetic...
Article
Full-text available
This study shows the possibility to synthesis ceramic pigments via solid-state high temperature sintering. The preparation of high temperature ceramic pigments using colourless stable crystal carcasses turns out to be quite suitable method in the case of ZrSiO 4 and their colouring by introducing different chromophores. The paper reports for experi...
Article
Full-text available
This study shows the possibility to synthesisze ceramic pigments via solid-state high temperature sintering. Willemite ceramic pigments, doped with Co and Ni as well as Fe-Zn spinel ceramic pigments were synthesized. The starting materials used for the synthesis are CoO, ZnO, CoO, Fe 2 O 3 , NiO and SiO 2 obtained from bio waste-rice husk ash. The...
Article
Full-text available
In this study willemite ceramic pigments, doped with Ni were synthesized. The optimal parameters of the synthesis process have been determined. The willemite is a mineral (zinc silicate) with formula Zn 2 SiO 4. For the production of willemite ceramic pigments in the system NiO-ZnO-SiO 2 we have used the following main materials: ZnO, NiO and SiO 2...
Chapter
The continuously increasing human population and the resulting growth in customer demand, combined with the impoverishment of the natural sources of raw materials and the resulting pollution of the environment impose the need for the efficient recycling of materials in practically all branches of industry. Specifically, in the ceramic and glass pro...
Article
Full-text available
Zinc silicate α-willemite (Zn 2 SiO 4) is an orthosilicate with rhombohedral symmetry. Cobalt doped willemite is a pigment with application in high-temperature ceramics and glaze production. A full series of cobalt containing wil-lemite ceramic pigments with composition xCoO. (2-x)ZnO. SiO 2 , where x = 0.125, 0.250, 0.375, 0.50, 0.625, 0,75, 0.875...
Article
Full-text available
The present research work is based on the comparative evaluation of the Ca, Mg, and Co dopant impact on the properties of new ceramic pigments from the system Fe2O3·SiO2 obtained via classical ceramic technology. This approach enabled determination of the optimal temperature for the synthesis and the most appropriate mineralizer. The obtained speci...
Article
Full-text available
Alternative technological approach is proposed enabling utilization of raw materials from an oil refinery, such as waste guard layers from reactors. Reagent grade and purified MgO, Cr2O3, Fe2O3, and nitric acid (HNO3), were used as additional precursors. The homogeneous mixtures obtained were formed into pellets and sintered at different temperatur...
Conference Paper
Full-text available
Innovation in teaching and learning of microbiology-painting with pigment microorganisms: In the present work are presented innovations in teaching and training in microbiology. For the first time has been applied " microbio art " by painting with living pigmented microorganisms. The innovation makes the students active participants in the studying...
Article
Full-text available
The synthesis of arsenic-free ceramics from industrial waste is studied. Samples of waste containing siliceous material passed the exploitation leap-guard layer shift reactor whose main oxide is -Al2O3 and, with the addition of natural raw materials and pure oxide, arsenic-free ceramics were synthesized with thermal and electrical properties relate...
Article
Full-text available
The Al2O3-matrices (20 \xm) are formed in H2SO4 and are subsequently electrolytically coloured in a CuSO4 solution. Good absorption properties in the wavelength range 200-2500 nm are ascertained. The approach of s.c. "color space" proves to be a convenient one for interpretation of the colour characteristics of these coatings in the visible range a...
Article
Zircon ceramic pigments with grey, lilac, and grey-lilac colors have been obtained using the technology developed for solid-phase sintering based on the raw materials SiO2 · nH2O, ZrO2 and MnO2 , Co3O4 , and NiO as the source of chromophores. The sizes of the crystals range from 2 – 5 to 10 μm, respectively. The synthesized pigments are investigate...
Article
Using the method of thermal degradation of salts (pyrolysis), aluminium (CoAl2O4, NiAl2O4) and chromium (MgCr2O4, NiCr2O4) spinel powders with particle size 30-80 nm, average of 50 nm, were prepared. After heating at 1100-1200°C for 1 h, blue, green-blue and blue coloured pigments with crystal sizes about 1 nm were obtained.
Article
Glass-ceramics containing waste guard layer from facilities for hydropurification of diesel fractions Glass-ceramic materials with brown, yellow-green and green-brown color and marble-like structure were obtained using a glass composition based on bulgarite and corrected by introduction of a waste product, i.e. exhausted guard layer from the diesel...
Article
Full-text available
The preparation of high temperature ceramic pigments using colorless stable crystal carcasses turns out to be quite a suitable method in the case of ZrSiO 4 and their coloring by introducing different chromophores. The paper reports experiments carried out on the synthesis of zircon pigments with the participation of following chromophore ions: Fe...
Article
Full-text available
Starting from the initial materials SiO2·nH2O and ZrO2, chromophore components were synthesized using Cr 2O3, Fe2O3 and Cu2O. A scheme was devised using isothermal 4 hour sintering at 800 °C, 900 °C and 1000 °C, under laboratory conditions, to produce zircon ceramic pigments with chromophore ions incorporating Cr3+, Fe3+ and Cu2+. The final phase z...
Article
in order to obtain high temperature ceramic pigments using colorless stable crystal carcasses turns out to be quite suitable in the case of ZrSiO4 and their coloring by introducing different chromophores. In the paper presented experiments have been carried out on synthesis of zircon pigments from the ZrO2-SiO2-Fe2O3 system. The technology of solid...
Article
La obtención de pigmentos cerámicos de alta temperatura a partir de cristales estables incoloros, puede ser muy viable en el caso del ZrSiO4 y su posterior coloración con diferentes cromóforos. En este artículo se han desarrollado pigmentos de zircón basados en el sistema ZrO2-SiO2-Fe2O3, utilizando la tecnología de sinterización en fase sólida. La...

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Projects

Project (1)
Project
The aim of the present project is to study the possibilities to synthesize ceramic pigments from pure and waste materials with respect to their possible use as pigments in the silicate industry. The ceramic pigments are inorganic colored finely dispersed powders which, when added to certain medium, impart specific color and change some properties. Besides their coloring ability, the ceramic pigments are resistant to atmospheric and chemical influences, high temperature, decomposing effect of silicate melts and light. These colored inorganic substances have high coefficient of refraction, they are insoluble in water and binding materials but can be dispersed within them, thus imparting certain color to them. It is intended to focus the efforts of the team on investigation of the possibilities to utilize waste products, e.g. various catalysts used in Lukoil Neftochim Bourgas by developing ceramic materials on their basis. The other important waste material selected for the studies is biomaterial (rice husks) which will be used as source of SiO2 for the preparation of ceramic pigments. The development of blends and technological scheme for utilization of waste materials for manufacturing of ceramic materials is based on an extensive literary material and, of course on the rich experience of the team in this field. Our special interests will be focused on the planned profound studies on the structure and mechanism of the synthesis of four types of pigments – spinel, willemite, garnet and zircon pigments using new and modern methods which will provide possibilities to find the correlation between them and develop optimal conditions for their synthesis. Our choice to focus on the synthesis of new kinds of ceramic pigments is based on the growing importance of ceramic materials, powders and pigments, as well as the diverse possibilities for obtaining them from both traditional and waste materials, as well as their potentially wide practical use in ceramic and glass industries, e.g. coloring of ceramic tiles and other articles, mosaic tiles, coloring of glass to obtain various types of colored glasses, etc. their color palette is constantly widening with respect to production of over-glaze paints and coloring of glazes for the ceramic industry, e.g. for the tile production.