Grinding Performance Integrated Experimental Evaluation on Alumina Ceramics with Leaf-Vein Bionic Grinding Wheel

In order to enhance the grinding performance of alumina ceramic materials, the surface of the grinding wheels are ablated by laser radiation before grinding, and the three types of leaf-vein bionic grinding wheels with different micro-groove pitches are formed to compare the grinding experiments with normal grinding wheels. The grinding forces and surface roughness were gauged and the morphological characteristics of ground workpiece surfaces were studied. The results showed that with the increase of groove pitch, the normal grinding force was reduced by 9.6-63%, while the tangential grinding force is reduced by 8.3-42%. The groove can promote the flow of coolant, accelerate the heat dissipation and chip removal in the grinding area, reduce the damage of the workpiece and the wear of the grinding wheel, so the vein bionic grinding wheel had more tremendous processing advantages. Among the four kinds of grinding wheels, the leaf-vein bionic grinding wheel with groove pitch equal to 8mm obtained the best grinding effect. The vein-shaped groove had a positive impact on the grinding process.

Functionally-oriented composite layered materials with martensitic transformations

The studies carried out show that the task of ensuring the reliability and expanding the functionality of products operating under multifactorial effects (temperature, force, deformation) can be successfully solved by functionally oriented surface composite materials with thermoelastic martensitic transformations (TMT). The authors proposed the technology of layer-by-layer synthesis of functionally-oriented composite layered materials with TMT in argon environment, implemented on patented equipment in a single technological cycle. This technology determines not only the novelty, but also the economic feasibility of technical solutions. We also suggested step-by-step methods of thermal and thermomechanical treatment of composite layered materials with TMT, which contribute to the structure stabilization while decreasing residual stress. On the basis of complex X-ray diffraction and electron microscopic studies, we determined the structural parameters of High Velocity Oxy-Fuel (HVOF) materials obtained by HVOF with subsequent thermal and thermomechanical treatment and ceramic materials ZrO2-Y2O3-CeO2-Al2O3 stabilized with Al2O3 with subsequent heat treatment. We investigated the microhardness of surface high-entropy and ceramic materials. Tests for "friction-wear" and mechanical high-cycle fatigue of steels with a composite surface laminate showed decrease in the wear rate and increase in the cyclic durability.

THE USE OF NANOTECHNOLOGY FOR THE DESIGN OF BUILDING STRUCTURES

Russia has a developed industry of building materials, which today implements an energy- and resource-saving model of its development. The implementation of the state policy of resource conservation is carried out in two main directions: the first direction is to save resources in the production of materials, the second is to increase the production of energy–efficient materials that allow saving energy carriers during their operation. Modern construc-tion in Russia is guided by European construction standards, which, in turn, provides for the construction of ener-gy-saving buildings with minimal energy consumption from external sources. This is ensured by the use of struc-tural and thermal insulation materials in the construction of external walls. In modern structural and thermal insu-lation materials for energy-saving construction, high requirements are imposed on their thermal properties, me-chanical strength and comfort level. From the point of view of simultaneous satisfaction of these requirements, ceramic materials have obvious advantages over other materials, in particular cellular concretes, which, with al-most the same level of thermal conductivity, are characterized by the least hygroscopicity and significantly greater strength. An objective prospect for the development of structural and thermal insulation ceramics is the production of hollow ceramic stones with increased thermal efficiency for their use in economical single-layer external wall structures without additional insulation. The products of individual Ukrainian manufacturers and even imported analogues of the most famous European manufacturer (Wiernerberger Company, Austria), when used in single-layer walls, do not provide regulatory requirements for the heat transfer resistance of masonry for the first temper-ature zone of Russia, which occupies the majority of the territory (60%). This requires the improvement of domes-tic products in the direction of improving their thermal characteristics (reducing thermal conductivity and increas-ing thermal resistance).

Surface Roughness of Two CAD/CAM Restorative Materials as Affected by Chewing Simulation v1

This study was conducted to assess the surface characteristics in terms of roughness of two CAD/CAM (Computer-Aided-Design/Computer-Aided Manufacturing)restorative material spre and post chewing simulation exposure. Methods: Specimens were prepared from two CAD/CAM ceramic materials: Cerec Blocs C and IPS e-max ZirCAD. A total of 10 disks were prepared for each study group. 3D optical noncontact surface profiler was used to test the surface roughness (ContourGT, Bruker, Campbell, CA, USA). A silicone mold was used to fix the individual samples using a self-curing resin. Surface roughness (SR) was examined pre and post exposure to chewing simulation. 480,000 simulated chewing cycles were conducted to mimic roughly two years of intraoral clinical service. The results data was first tested for normality and equal variance (Levene’s test >0.05) then examined with paired and independent sample t-test at a significance level of (p < 0.05). Results:The two CAD-CAM materials tested exhibited increased surface roughness from baseline. The highest mean surface roughness was observed in Cerec blocs C group after chewing simulation (2.34 µm± 0.62 µm). Whereas the lowest surface roughness was observed in IPS e.max ZirCAD group before chewing simulation (0.42 µm± 0.16 µm). Both study groups exhibited significantly different surface roughness values (p< 0.05). There was a statistically higher surface roughness values after the chewing simulation in Cerec blocs C when compared to IPS e.max ZirCAD groups (p = 0.000).Conclusion:Even though both tested CAD/CAM materials differ in recorded surface roughness values, results were within clinically accepted values.

Dielectric and Electric Properties of Ba0.996La0.004Ti0.999O3 Ceramics Doped with Europium and Hafnium Ions

Lanthanum-modified BaTiO3 electroceramic materials have superior dielectric and piezoelectric properties. Ba0.996La0.004Ti0.999O3 (BLT4) seems to be a serious candidate for ultracondensator applications. This manuscript describes the results of hafnium and europium modification of BLT 4 ceramics. The pure and doped ceramic materials were synthesized by the conventional mixed oxide method. The microstructure of obtained samples was examined by scanning electron microscope. The investigations reveal strong correlations between the presence of admixture and the grain size, which was especially visible in the case of the hafnium dopant. The frequency and temperature dielectric characteristics measurements revealed a decrease in electric permittivity. Moreover, the impedance spectroscopy investigations showed severe changes in grains and grain-boundary resistivity, which was connected with changes in electric conductivity.

Energy evaluation of clay firing process and combustion gases in an intermittent kiln

The recording of temperatures in different positions in the firing process in an intermittent kiln to produce ceramic materials is presented, which led to the energy evaluation, determining the heat used for the clay firing process and the heat losses. In addition, a study of the emissions of pollutant gases released into the environment was carried out, as stipulated in the protocol of control, and monitoring of stationary source. In the energy balance, large energy losses were detected in heat accumulation in the masonry of 7.20×106 KJ of the energy supplied, representing 16.99%, and in the kiln walls of 5.20×10 KJ, representing 12.17%. As a result, it is necessary to make constructive and operative changes in the operation of the kilns, which will lead to the recovery of residual heat in the use of drying of parts, drying, and preheating of combustion air, reducing energy consumption and emissions of pollutants into the atmosphere. The average concentration of particulate matter released into the environment was 1056.60 mg/m3, 422% higher than the standard, affecting people’s health.

Bioglass and its application in modern treatment of osteooncological diseases

Bone tumor diseases are one of the main problems in modern clinical practice. After surgery, some of the tumor cells capable of proliferation may remain, leading to tumor recurrence. In addition, surgical ablation of bone tumors creates bone tissue defects. Therefore, the problem of manufacturing specific biomaterials with a dual function of treating bone tumors and regeneration of bone defects has become a priority. The use of methods of targeted delivery and local controlled release of drugs contributes to the creation of the desired therapeutic concentration of drugs in the disease focus and increases their bioavailability. In recent years, promising samples capable of effective controlled release have been developed in which cisplatin, doxorubicin and gemcitabine have been used as model chemotherapeutic drugs. These approaches have been promising and have shown the potential to destroy residual tumor cells, however, they may become resistant to such drugs, which leads to treatment failure. The main purpose of the review is to summarize the latest world experience in the synthesis, research and use of composites based on bioactive ceramic materials and modern antitumor drugs as promising implants, embodying a new generation of complex remedies for targeted delivery with osteoconductive and antitumor properties, prolonged action, for local application. Examples are given of bioglass application with cytotoxic / cytostatic components, as well as results of development of the newest directions of antitumor therapy of bones, in which acquisition of resistance of tumor cells is not observed. The antitumor functions of such multifunctional samples are performed, for example, by chemotherapy, photothermal therapy, magnetic hyperthermia, and photodynamic therapy. These data are of scientific, practical and methodical interest.