International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Barium titanate ceramics doped with samarium were synthesized by low temperature sol-gel method. The physicochemical characterization of the samples was carried out by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). A pure BaTiO3 cubic phase was obtained. A technological regulation has been developed for the preparation of test samples .Monitoring ofthe relative dielectric permittivity of Sm-doped BaTiO3 ceramics with temperature changes (at frequency of 10 kHz) was realized.The resulting curve is typical of ferromagnetic material. The synthesized barium titanate ceramics possesses a high dielectric constant – 17500 at a Curie temperature Tc (65oC). The obtained values for the relative dielectric permittivity and Curie temperature of Sm-doped barium titanate ceramics are much better in comparison to conventionally non-doped BaTiO3-εr = 2000 and Tc = 120°C.

Subject of the present paper is the measurement of temperature changes in the ceramic cavity walls of Dadant Blatt beehives. Using a FLIR P640 infrared camera and two different heat sources, 80 thermogramsof ceramic cavity walls were obtained. The infrared images of the studied objects are divided into rectangular zones. The results of the study are presentedtabularly and graphically.

The article presents a study of the sound and thermal insulation properties of ceramic plates with cavities, designed for beehives. The plates are obtained by the “casting” method from a water-dispersed colloidal system based on a patent-protected quartz glass-ceramic. They are composed of amorphous SiO2, mullite and cristobalite. To measure the thermal conductivity, a thermal chamber is constructed with a heater installed in it. Given that the heat flow passing through the three-layer ceramic plate for beehives is constant, the temperature difference between the two opposite sides of the plate at steady state (at constant heat flow) is measured and the thermal conductivity is calculated. A two-chamber method is used to determine the sound insulation capacity of the ceramic plates for beehives. The sound pressure of the sound waves – the incident one and of the wave which has passed through the sample –is measured in the frequency range from 100 to 3150 Hz

The research is aimed at creating a target from Sn doped barium-titanate ceramics. A technological regulation for the preparation of test bodies from a material synthesized by a low-temperature sol-gel method has been developed. The physicochemical parameters of the samples were determined and the temperature dependence of the dielectric permittivity was monitored. Physicochemical characterization of the samples was performed by X-Ray diffraction (XRD). and scanning electron microscopy (SEM). The preparation of pure BaTiO3 cubic phase was established. The dielectric permittivity of Sn doped barium-titanate possesses a maximum value of 45000 at a Curie temperature- Tc 40oC.

In recent years, interest in the application and use of materials for supercapacitors for electric vehicles has grown significantly. The advantage of capacitor ceramics over other dielectric materials for producing supercapacitors is its environmental friendliness and high economic efficiency. This paper presents the results of a study of capacitor ceramics doped with Sn at different locations of the modifier (tin) in BaSnTiO3 and BaTiSnO3 crystal lattice. The influence of modifiers in low-temperature sol-gel synthesis was studied. The samples were annealed at 1000°C. The resulting phases were identified by X-ray phase analysis. Microscopic analysis was also performed.

In recent years, scientists have turned their attention to the synthesis of a new class of amorphous materials – glass with the participation of SeO2 (selenite glass), and to the study of their structure. Among the established centers for systematic research on these materials are the Institute of Metal Science, Equipment and Technologies with Center for Hydro- and Aerodynamics “Acad. A. Balevski” at the Bulgarian Academy of Sciences (IMSETHC – BAS) – Sofia, Bulgaria and the Department of Silicate Technology at the University of Chemical Technology and Metallurgy (UCTM) – Sofia, Bulgaria. These types of glass have specific properties such as high permeability in the visible and the near infrared regions of the spectrum, high refractive index, and low melting point. On the other hand, the amorphous materials in this class of can serve as model compositions. The obtained structural information can be used to form generalizations about the vitreous state and the possibility to modify the structure and properties of glass in order to improve the technological parameters.

This article deals with the study of the cavity of ceramic constructional elements for the construction of beehives and carriers for electric furnace heaters. Unlike the traditional practice of performing tomography studies to determine the structure and harmful defects in the interior and surface of specimens, in the present studies, the non-destructive non-contact method is used to assess the nature and volume of deliberate fulfilled cavities in ceramic specimens. The role of well-shaped and regulated cavities is to reduce the coefficient of thermal conductivity in the hives to the inside, and in the carriers for heaters to the outer walls of the furnace, i.e. heat loss. The cavity samples are obtained from an aqueous dispersed colloidal system based on patent-protected quartz glass-ceramics by the “pouring” method. The obtained structural details are fireproof, thermally stable and with high physical and mechanical characteristics. They are composed of amorphous SiO2, mullite and cristobalite. The study of the cavity at different beam depths was performed using a NIKON XTH 225 device, and the data processing Volume Graphic, My VGL.

The sol-gel process is a well-known and reliable process for obtaining materials and coatings of different structure and properties. An important feature of this method is the choice of starting precursors to obtain the desired compositions. The complexity of the technology is due to the difficult process control. For this purpose it is necessary to accurately calculate the stoichiometry to obtain the final phase. Thus, the sol-gel technology is widely used as in the production of coatings by immersion and spraying, aerogels and others. However, there are many other applications such as electronic materials that have not yet been well studied. In this study, after a brief explanation of the process, some of the most important applications are considered.

In this paper we present the results of atomic force microscopy (AFM) characterization of the surface morphology of the nanostructured titanium oxide films featuring with Sm2O3 by the sol-gel method in order to increase the corrosion resistance of stainless steel. Two types of titanium precursors were applied – titanium (IV) isopropoxide Ti[OCH(CH3)2]4 and titanium(IV) butoxide Ti(OCH2CH2CH2CH3)4.

The proposed review looks at some aspects concerning ferroelectrics that are characterized by high dielectric constant at/ or near Curie temperature. Particular attention haс been paid to the doping of BaTiO3 with rare earth elements because they prove to be very promising for the production of supercapacitors. It is pointed out that the preparation of ceramic materials with high dielectric permittivity by sol-gel method is of huge interest due to the numerous advantages inhered to this technology.

Sol gel TiO2-ZrO2 composite films were dip coated on stainless steel substrates and treated at 300, 400 and 500oC. The morphology and surface features were examined by Scanning electron microscopy (SEM) and X ray photoelectron spectroscopy (XPS). Xray diffraction analyses (XRD) was applied to investigate the phase composition. The corrosion resistances of the coatings were studied by evaluation of the weight loss in NaCl medium. According to XRD while the Zr-Ti composites are amorphous after treatment even at 500oC. The surfaces of the coatings possess typical island structure. The coatings, treated at 500oC ehxibit higher corrosion resistance than the other two type of samples. This could be explained by the amorphous structure of the composites, which lowers ion and electron conduction, high hydrophobicity and lower oxygen content.