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

Based on waste biogenic calcium carbonate CaCO3 and silicon dioxide SiO2, polyphase materials with a predominant content of calcium silicate phases and a limited presence of silicon dioxide were synthesized in laboratory conditions. When preparing the experimental samples, solid-phase synthesis and thermal treatment modes with a maximum temperature of up to 1300oC were used. During the X-ray phase analysis of the obtained experimental samples, the presence of Ca3(SiO3)3 pseudowollastonite (dominant phase) was registered, β-Ca2SiO4 and SiO2 cristobalite. The main possibilities for further expedient modification of the used technological regimes are analyzed. The prospects for potential application of the synthesized phases for the preparation of various functional materials are considered. The study is consistent with modern trends in the use of technological approaches that allow the utilization of waste materials.

Composite structural modifications based on hydraulic inorganic binders and foam glass aggregate fractions were prepared. Formwork moulds were developed for the moulding of composite test bodies using different technological approaches. A series of experimental specimens meeting the requirements for standard laboratory tests were obtained. The role of the technological regimes used in the formation of the structural characteristics and performance of the composites is examined. The existing possibilities for further modification and potential application of the obtained composite materials are analysed.

Applied research work carried out for the development and manufacture of an innovative movable frame ceramic hive with increased operational stability and efficiency is presented. A brief justification of the design solutions used and the choice of the applied technological approach is made. The main stages of the developed technological regime for the preparation of structural ceramic elements and various modifications of experimental prototypes are discussed in a summarized form. The existing possibilities for the production of new modifications of ceramic beehives with improved performance chracteristics by applying different technological approaches are analyzed. The technological regime for the preparation of structural details is fully compatible with the production methods typical for the ceramic industry and provides the opportunity for further implementation.

The technological characteristics of suspensions used in the development of new thermal insulation composite structural elements based on foam materials and inorganic binders (Portland cement) are investigated. The role of the components of the compositions, the parameters of the technological regime and other factors in ensuring adequate workability of the prepared cementitious solutions is considered. Determination of the necessary technological characteristics of composite mixtures ensures their effective distribution in the formwork moulds when forming the specimens, cost-effective performance at production stage and obtaining products with the planned
functional properties. The existing opportunities for potential application in modern construction of the developed composite elements are analyzed.

The development refers to an innovative technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics. The conditions for obtaining stable suspensions from quartz glass are emphasized and investigated. The time for the treatment of the glass in the grinding device, the amount of water, the influence of the modifiers in stabilizing the suspension by adjusting the pH level, as well as the most suitable sedimentary composition of the glass particles are established. The factors determining the speed and degree of sintering of the ceramics are investigated and established. They include the density of the raw products, the dispersion of the quartz glass particles and its purity, as well as the environment in the furnace and the sintering mode.

The results of the plastic forming of ceramic pavers with a large volume and size are observed to produce better compaction of the raw material. The used ceramic mixture is based on a sedimentary rock with relatively high moisture content and firing shrinkage which gives the common yellow colour after a high-temperature liquid phase synthesis. The results of one-fold pressing revealed the occurrence of deformation processes in the drying stage and during the temperature regime. As a consequence, the pressing pressure should be increased and the residual water amount needs to be reduced to an optimal content.

The phase and petrographic analysis of a part of previously prepared test samples of coloured petrographic materials coloured with different contents of CuO, SnO2, CoO, Cr2O3 were studied. The raw materials are based on metamorphic rocks – dolomite marbles from the village of Ustrem and the village of Mramor, processed by melting at 1450°C, so that after crystallization, petrographic phases are obtained, which are confirmed by X-ray phase and petrographic analysis. The main characteristics of the colouring aggregates and their effect on the mineral composition and crystal structure are described.

The research is related to the creation of new compounding formulations for the production of “yellow” paving stones. This was necessary due to denied access to a potential source of suitable raw material from the deposit near the village of Svetlen, Popovo municipality. Marlstone raw material from this deposit has the necessary qualities for such production, as a result of which, after hightemperature liquid-phase synthesis, new petrurgic phases with high physicochemical and mechanical properties can be formed. The new compounding formulation of the molding mass was developed on the basis of marlstone sedimentary rock from the Alexandra deposit, located near the village of Lovets, Targovishte district. The use of this compounding formulation makes it possible to obtain appropriate physicochemical and mechanical properties and a yellow coloring equivalent to that of the reference samples.