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

Bulgaria has a variety of deposits (mainly in northeastern Bulgaria) of sedimentary rocks (marls) suitable for the development of compounding formulations and technology for the production of stone products. On the basis of some of these sedimentary rocks (marls), experimental technologies for innovative formulations with modifiers for usable petrurgical materials are developed and tested. The first prototypes of ballistic protection products are obtained, with physic-mechanical properties better than those when only natural sedimentary rock is used, and lighter and cheaper than in the case of corundum and silicon carbide.
The properties of these materials allow for certain alternative applications such as the ballistic protection of ground-based mobile and stationary objects. They also make possible the production of quality articles with protective properties against high-speed kinetic effects, but at significantly lower cost than when traditional materials are used.

Bulgaria has a variety of deposits (mainly in northeastern Bulgaria) of sedimentary rocks (marls) suitable for the development of compounding formulations and technology for the production of stone products. On the basis of some of these sedimentary rocks (marls), experimental technologies for innovative formulations with modifiers for usable petrurgical materials are developed and tested. The first prototypes of ballistic protection products are obtained, with physic-mechanical properties better than those when only natural sedimentary rock is used, and lighter and cheaper than in the case of corundum and silicon carbide.
The properties of these materials allow for certain alternative applications such as the ballistic protection of ground-based mobile and stationary objects. They also make possible the production of quality articles with protective properties against high-speed kinetic effects, but at significantly lower cost than when traditional materials are used.

Zirconium dioxide-titanium dioxide coatings were obtained by sol-gel method on stainless steel plates. The samples were treated at three Zirconium dioxide-titanium dioxide coatings were obtained by sol-gel method on stainless steel plates. The samples were treated at three temperatures 300, 400 and 500oC. The morphology and chemical surface composition were examined by Scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), while the phase composition was examined by X-ray diffraction analyses (XRD). The corrosion resistance was evaluated by weight loss measurements in NaCl medium. The coatings are possess relatively smooth surface with some microcracks. After corrosion test the coatings treated at 500oC, keep their surface structure without visible signs of corrosion and thecorrosion tests revealed zero mass loss. The good protective properties of these coatings could be attributed to (i) amorphous structure, leading to deterioration of the ion and electron conduction of the films and (ii) probably increased density after the thermal treatment

Based on the experience gained during the creation, experimentation and study of two devices and technologies for the production of foam glass from household glass waste according to Bulgarian Patents Nos. 65718/24.11.2004 and 65745/26.05.2006, an idea was developed for a new device for which a patent application has also been filed. The basic operational concept of the previous devices is preserved, but some of their deficiencies discovered during their experimentation have been corrected.

Test recipes of petrurgical materials, based on basalt raw materials and technological additives were developed. The influence of the additives used, their quantities and the mode of thermal treatment on the crystallization processes in the experimental samples was investigated. Products with microcrystalline structure and predominant crystalline phase of augite were obtained. By applying the gas counter-pressure casting method and a set of precision casting molds, products with a variety of mechanical and physicochemical characteristics were obtained. The optimal technological conditions for the production of petrurgical materials, suitable for the making of technical equipment with application in different industries, were established experimentally.

Three types of oxide sol gel coatings: TiO2, CeO2 and TiO2/CeO2 composite were deposited by sol gel method on stainless steel and carbon steel. The morphology was examined by means of Scanning electron microscopy (SEM). X-ray diffraction analyses (XRD) were applied to investigate the phase composition. The corrosion resistances of the coatings were studied by evaluation of the weight loss in NaCl medium for 1200 hours. The surface of the TiO2 samples were relatively dense with a few surface nanocrystals and after tests does not shown any signs of corrosion. Тhe composite TiO2/CeO2 samples possess deep cracks which evidently favor the attacks in corrosion medium. Ceria and titania coatings deposited on stainless steel have zero weight loss in corrosive medium. The TiO2 coatings could also effective protect carbon steel, while the TiO2/CeO2 and CeO2 coatings exhibited lower corrosion resistance.

The development deals with the study of the conditions for appearance of yellow color in ceramic products, obtained from local sedimentary marl rocks from the region of Popovo town, field of Targovishte. Reproduction of the conditions of high temperature liquid-phase synthesis of products such as pavings, tiles, etc., by modifying the composition of the marls. Expanding the sintering interval of rectifying the alkaline-earth oxide content and increasing the phase formation time. The researches are part of the creation and implementation of a technology for production of pavings with equivalent yellow color of the imported standards but with higher tribological and physic-mechanical indicators.

Titanium dioxide coatings and zirconium dioxide were deposited on SiO2 underlayers by sol-gel method on stainless steel plates. The samples were treated at two different temperatures (500 and 700oC) in air. The morphology was examined by means of Scanning electron microscopy (SEM) and the phase composition by X-ray diffraction analyses. The corrosion resistance of the coatings were examined by evaluation of the weight loss in NaCl medium. The TiO2/SiO2 coatings possess relatively smooth surface with some crystallites on the surface, while ZrO2/SiO2 coatings are not so smooth. After treatment at higher temperature the ZrO2/SiO2 coatings become rougher. The weight loss measurement have proved that the TiO2/SiO2 coatings exhibit higher corrosion resistance in comparison to ZrO2/SiO2 coatings. The TiO2/SiO2 coatings, treated at 500oC after the corrosion test retain their characteristic grain structure without any cracks and other defects. Similar is the structure of these coatings, treated at 700oC. The better protective properties of TiO2/SiO2 could be attributed to their amorphous dense structure.