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Abstract

In the process, inorganic complexes of amidoamines obtained from the interaction of natural petroleum acid and oleic acids with diethylenetriamine have been developed and their effectiveness as inhibitor-bactericides has been investigated. The effect of the synthesized reagents on the kinetics of the corrosion process of steel and the activity of sulphate-reducing bacteria in 3% NaCl solution saturated with CO2 and in the biphasic water–isopropyl alcohol medium with H2S dissolved has been analyzed. The thermodynamic and kinetic parameters of the corrosion process were calculated. The adsorption of the complexes was investigated using the Langmuir isotherm and the correlation constant was determined. State of the metal surface was investigated by SEM method in CO2 and H2S media, with and without inhibitors, and the metal surface contact of complexes was studied by computer molecular simulation.

Abstract

The electrocatalytic reduction of carbon dioxide into valued chemicals such as formic acid has the most promising potential in applying renewable energy for useful materials and mitigating the greenhouse effect. However, the studies still focus on developing catalysts with low price and high catalytic properties. In this study, nitrogen atoms were decorated into carbon structure by a unique ultrasonic method, then the nitrogen-doped carbon material was applied as catalyst in CO2 reduction, it exhibited excellent electrochemical activity, 4 times higher than the normal method. The improved activity should be attributed to the interaction between nitrogen and carbon atoms through analysis.

Abstract

This work presents the development of a solid product with a high water content (99.08%) and water retention properties. Water was chosen as a potential carrier of a volatile active substance and water retaining properties of material were studied at a temperatures and relative air humidity values with the support of the theory of drying. The study first confirmed the role of Gibbs’ phase rule in the research of solid-gas phase equilibrium, and second presented drying kinetics developed from Fick’s second law and expressed with the first term of the Fourier equation. Solutions of equations for phase equilibrium and mass transfer enabled the calculation of Luikov’s parameters, which are important for equilibrium relations and for the diffusivity of water in a solid for mass transfer prediction. The obtained thermodynamic and kinetic parameters enabled product characterisation that may be important for the prediction of retention times.

Abstract

In this study, activated carbon and humic acid powder were fixed by the cross-linking reaction of sodium alginate. Calcium alginate/activated carbon/humic acid (CAH) tri-system porous fibers were prepared by the wet spinning method and freeze-dried for the removal of tetracycline in aqueous solution. Subsequently, the morphology and structure of CAH fibers were measured by scanning electron microscopy (SEM) and the Brunauer-Emmett-Teller (BET) method. The effect of pH, contact time, temperature and other factors on adsorption behavior were analyzed. The Langmuir and Freundlich isotherm models were used to fit tetracycline adsorption equilibrium data. The dynamics data were evaluated by the pseudo-second-order model, the pseudo-second-order model and the intraparticle diffusion model. Thermodynamic study confirmed that the adsorption of tetracycline on CAH fibers was a spontaneous process.

Abstract

The aim of the study was to present numerical strength analysis of the virtual knee and hip joints for the most popular tribological pairs used in prosthetic arthroplasty based on the Finite Elements Method. FEM makes it possible to calculate the stress in particular elements of the tested models. The research was dedicated to elucidate abrasive wear mechanisms during surface grinding of a polyethylene UHMW and a metal elements of endoprostheses. Strong adhesion was found between the abrasives and workpieces, which might be attributed to the chemical bonding between the abrasives and workpieces in synovial liquid. Therefore, the wear of UHMWPE is both chemical and physical. Abrasive wear effect, as a result of the abrasive wear process, is associated with material loss of the element surface layer due to the separation of particles by fissuring, stretching, or micro-cutting.

Abstract

In this work, a series of Natural Rubber (NR)/Styrene Butadiene Rubber (SBR) blends were formulated to protect metallic petrochemical storage tanks from corrosive media. Therefore, these blends tested against a 10% HCl solution for 72 hr at room temperature. Blends series were prepared with different ratios of NR/SBR; 25/75, 30/70, 35/65, 40/60, 45/55, 50/50, and 55/45. Three types of carbon black (N-330, N-660, and N-762) were added individually to the 45/55 blend. Hardness, tensile strength, modulus, and elongation properties were tested before and after immersion in the 10% HCl attack media. All these mechanical properties decreased after immersion action accept hardness property. Up to 45 phr NR content, the hardness increased linearly independent on immersion action, but HCl immersion gives higher hardness values. Tensile strength increased up to 40 phr NR content with and without immersion and the immersion action decreased tensile values. The highest elongation value obtained with 35/65 blend with and without immersion. The 45 phr NR content gives the higher modulus, while the lowest value obtained with the 30 phhr content. For 45/55 blend, the hardness increased as the carbon black particle size decreased and immersion action gives higher hardness values. The tensile strength decreased linearly with the carbon black surface area, while with the medium surface area, the highest modulus and lowest elongation obtained.

Abstract

The processes of corrosion-fatigue failure of materials in contact with mineral fertilizers are insufficiently studied. As a result of joint influence of atmospheric corrosion and mechanical loads, about 70 to 80 % of machine parts get out of order, 20 to 25 % of which are failures caused by operating overload due to the strength loss because of atmospheric corrosion. A large part of metal structures of agricultural vehicles used to transport mineral fertilizers is under the direct influence of aggressive environments and dynamic loads that occur during the motion by field roads. Saturated solutions of the most aggressive working environments used in agricultural production, in particular ammonium sulphate and nitrophosphate are investigated to reduce fatigue resistance of ordinary steels groups – St3 and St5 and quality steels – 10 Steel, 15 Steel, 20 Steel, 25 Steel when loaded at all levels. The fatigue endurance limit decreases in comparison with air up to 2.02 times in a solution of ammonium sulphate, and to 2.32 times in a solution of nitrophosphate. In organic fertilizer environments, compared to distilled water, the conditional fatigue endurance limit increased to 9 %. The properties of the given materials as an inhibitor of corrosion-fatigue failure were discovered and proved.

Abstract

A novel pyridine derivative was synthesized, and its corrosion inhibition effects on mild steel in a 1M hydrochloric acid environment were investigated by gravimetric techniques, The results demonstrated that the inhibitive performance increased with the increasing of inhibitor concentration. At 303, the inhibition efficiency of pyridine derivative 4-hydroxy-3-(pyridin-2-ylaminomethyl)toluene accomplished 96.2% at the inhibitor concentration of 0.005 M. The mechanism of inhibition implicated the forming of a protective layer from inhibitor molecules on the surface of mild steel by a Langmuir adsorption isotherm. The presence of nitrogen and oxygen atoms in the structure of 4-hydroxy-3-(pyridin-2-ylaminomethyl)toluene confirmed by CHN-analysis revealed the adsorption of inhibitor molecules on the surface of mild steel surface.

Abstract

Ni-based coatings can be successfully applied under abrasive and adhesive conditions as a substitute for environmentally harmful chrome coatings. The research has been carried out for thermally flame sprayed Ni-based coatings with remelting (so-called the two-step process) with the different chemical composition of starting powders. The structure of coatings was evaluated by optical and scanning electron microscopy. Both the three-body abrasive wear test, according to ASTM G65-4 (Dry-Sand Rubber Wheel Test) and dry sliding wear test by the Falex tester, were performed. The results show the influence of the effective chemical composition of the metal powders on improving the properties of the coating. The higher hardness of the coatings leads to a lower tendency for the creation of adhesive bonds, and as a result, leads to a lower tendency to scuffing. A similar trend shows the influence of higher coating hardness on the increasing of abrasive wear resistance.

Abstract

In this paper, the effects of coupling agent and lignin extracted from waste cotton stalks in Xinjiang on thermal-oxygen aging properties of polypropylene (PP) composites were studied. The melt index test and indoor thermal oxygen aging test was carried out on the samples treated with coupling agent. The mechanical properties, surface micromorphology, rheological properties and element composition of the materials before and after 30 days of aging were studied. The results showed that the titanate coupling agent was the best for improving the melt index and mechanical properties of PP/cotton stalk lignin composites. After the 30-day thermal oxygen aging test, the samples with 2% lignin had the best impact strength and retention rate of fracture elongation, reaching 68.9% and 77.3% respectively. The sample with 3% lignin content had the smoothen surface, no crack appeared. After aging, the increase of C=O was the least, and the crystal peak area decreased less.