Geopolymer Composite Coatings Based on Moroccan Clay and Sands for Restoration Application

This study aims to explore geopolymer binders and mortars based on local Moroccan clays and sands as coatings for the restoration of historical monuments in Morocco. For this, five substrates, one geopolymer binder, and two geopolymer mortars were investigated. The characterization of substrates reveals differences in terms of pH value, capillarity, contact angle, and surface roughness. These differences affect the coating thickness, which also depends on the viscosity, liquid to solid ratio, and granular skeleton of the geopolymer coating. High adhesive strength values (up to 9 MPa) were obtained on limestones. However, these values decreased with the increase of relative humidity. In the case of Fez stone, a stable adhesive strength value (3 MPa) was evidenced for all the coating formulations and at different storage conditions confirming the suitability of coating based on metakaolin, Moroccan clays, and sands for restoration applications.

Changes in the structure and properties of ZrO2 detonation coatings during annealing

The article studied the effect of annealing on the structure and properties of zirconium dioxide coatings obtained by detonation spraying. Detonation spraying was realized on a computerized detonation spraying complex of the new generation CCDS2000. Determined that coatings made of zirconium dioxide are characterized by high adhesive strength of adherence to the substrate. Thermal annealing of coated samples was performed at temperatures of 900-1200◦ C. It was determined that the microhardness of zirconium dioxide coatings increases by 10-25% depending on the annealing temperature after annealing. The results of nanoindentation showed that the nanohardness of the coatings after annealing at 1000◦ C increases by 50%. It was determined that after annealing at 1000◦ C, the elastic modulus of the coatings increases, which indicates a decrease in plasticity and an increase in the strength of the coatings. X-ray diffraction analysis showed that the phase composition of coatings before and after annealing consists of t-ZrO2. After annealing occurs there is an increase in the degree of t-ZrO2 tetragonality. Electron microscopic analysis showed that an increase in the number and size of micro-continuity in the form of thin layers after annealing. Determined that increase the hardness of zirconium dioxide after annealing at 900-1200◦ C is associated with a higher degree of tetragonality t-ZrO2 phase.

Features of Obtaining Carbon Plastics Based on Superstructural Polymer Materials

The features of obtaining carbon plastics and specific solutions to problems associated with the compatibility of an inorganic filler and a polymer matrix, the formation of adhesive contact of carbon fillers due to the formation of chemical bonds, mechanical adhesions, local stresses and defects at the phase boundary are considered. Successful solutions are presented that provide high adhesive strength between the filler and the polymer matrix.

Corrosion-resistant composite germanium-based alloys coatings

The results of complex studies on the development of a powder composition Ge–Cr–Zr–Ce–WC, promising for the production of functional cold-resistant coatings by microplasma sputtering, are presented. The coating has high adhesive strength (more than 40 MPa) and microhardness (up to 10–12 GPa) and withstands repeated thermal cycling in the temperature range from –60 to 20°С.

ASSESSMENT OF BILIOSTATIC PROPERTIES OF MODERN TOPIC HEMOSTATIC MEANS USED IN HEPATIC SURGERY

Aim. To assess the biliostatic properties of modern topic hemostatic means and the developed glue composition for medical purpose, used in hepatic surgery in experiment. Materials and methods. The studies, aimed at assessment of the properties of local hemostatic means, were carried out on Wistar rats weighing 178 ± 10 g. The device for determination of leak proofness of hepatic stump with hydropression technique was used. Comparative estimation of elasticity and adhesive strength of hemostatic means, using tension testing machine “REM-10”, was fulfilled. Original polyurethane glue for medical purposes was developed and studied. Results. The glue compositions “Bioglue”, hemostatic sponge “Tachocomb” and original polyurethane composition for medical purposes with adhesive strength > 600 Pa (mm H2O) ( p < 0.05) possess the best adhesive properties. It was established on the basis of experimental data that the glue composition “Bioglue” and polyurethane glue composition have a high adhesive strength, elasticity and resistance to hydropression. Conclusions. 1. Glue compositions possess higher adhesion and endure higher level of pressure as compared with sponges and plates. Original polyurethane composition has maximum adhesive strength, elasticity and hydropression resistance. 2. After application of original polyurethane glue composition on resected liver (in experiment), it is completely lysed in 30-35 days.