Nowadays there is a need for new generation of biodegradable implants, which should be able to stimulate the healing responses of injured tissues at the molecular level. Magnesium alloys attract great attention as perspective bone implants due to their biocompatibility, physical properties and ability to degrade completely under physiological conditions. The main purpose of this research was assessment of in vitro corrosion and surface morphology after short term in vivo implantation of Mg based implant covered by hydroxyapatite (HA). Mg alloys with the addition of Zr (0.65%), Al (1.85%) and Nd (1.25%) were used. In our work, we propose dipping method for hydroxyapatite coatings formation which has been shown to reduce the corrosion rate of magnesium implants in vivo. Simulated body fluid (SBF; pH 7.4) with ion concentrations approximately equal to those of human blood plasma resembling physiological conditions and citrate buffer with pH 5—simulating inflammation were selected as modelling environments for in vitro degradation test. The rod samples were implanted into the tibia bone of rats and after 1 day and 5 days of implantation were taken out to observe cells adhesion on surface samples. SEM was used to assess surface morphology after in vitro and in vivo tests. SBF solution causes some cracks on the surface of HA coatings, while citrate solution at pH 2 caused complete dissolving of the coating. The HA coating favoured cell adhesion and rapid fibrous tissue formation.

The effect of microbial and chemical corrosion on concrete structures operated in the conditions of chemical enterprises has been established that makes it possible to reliably predict the timing of their decommissioning in order to prevent industrial disasters. Even though the construction complies with all building codes, concrete structures eventually undergo chemical and biological corrosion. The innovation proposed in this study implies investigating the depth and degree of damage to concrete at the microscopic level by the method of raster electron microscopy. In addition, the TPD-MS method has been suggested for determining the quantitative and qualitative state of the carbonate components of concrete and sulfur compounds. This study has found that in concrete samples from the titanium dioxide production plant, the amount of carbon dioxide release is twice less than in control samples at t=600 °C while the level of sulfur dioxide, on the contrary, increases. This is due to the ability of thionic bacteria to accumulate sulfate acid that destroys the cementing component in concrete. The reported results confirm the impact of products of the activity of Acidithiobacillus thiooxidans microorganisms on corrosion processes in concrete. In addition, when using the TPD-MS method, it was established in the storage room of the finished product that heating the control sample of concrete leads to a release of the significant amount of СО2 at t=580–600 °C. However, the experimental samples of concrete are almost lacking carbon compounds because the acid metabolites of microfungi interfere with its formation. Microscopic and REM studies revealed the localization of Acidithiobacillus thiooxidans and Aspergillus fumigatus in concrete. This study has established patterns related to the mechanism that forms chemical compounds in concrete and the metabolism of microorganisms

The process of Сd 2+ and Zn 2+ cations transfer through the cation exchange membrane RALEX®CM-PES 11-66 in double-chamber electrolyzer was investigated. Anodic chamber electrolyte (analyte) contained model solutions which imitates galvanic baths composition for passivation processes. The analyte contained 50 g/l sodium dichromate and 10 g/l sulfuric acid as main substances and impurities of Сd 2+ and Zn 2+ cations in amount of 2.5 g/l of each. The electrolyte of cathode chamber is catholyte, contained 1 % solution of sulfuric acid. The titanium grade BT-0 and lead grade C-0 were used as cathode and anode respectively. Cathode processes connected with processes of ion migration through the membrane and metal release on cathode were studied. The creation of volt-ampere curves in galvanodynamic mode was supplied by impulse potentiometer, tool for combined measurements and silver chloride reference electrode. An increase of cathode overvoltage in the presence of cadmium ions and decrease of cathode potential with the increase of temperature were proved. The pH range for intensive reduction of metals was determined during investigations. Scanning electron microscopy with X-ray analysis was used for estimation of cathode deposits elemental composition. It was established that metal atoms of cadmium and zinc were presented in cathode deposits. Transference numbers of ions through cationic membrane were calculated for cadmium and mixture of cations proved the effectiveness of chromium and zinc ions extraction from chromium containing solutions. This process provides regeneration of galvanic solutions and maintains stable composition of passivation bath.

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Long-term operation of reinforced concrete structures in the conditions of chemical enterprises has a powerful negative impact on the physical and chemical properties of concrete, which leads to its destruction. The aim of this research is to determine the effect of biological and chemical corrosion on concrete structures in the workshop for the production of titanium dioxide by the sulphate method and the storage of finished products. In particular, chemical production for the synthesis of titanium dioxide by the sulfate method causes the rapid course of chemical (acid and sulfate) and microbiological (thionic bacteria and microscopic fungi) corrosion processes. These corrosion processes reinforce each other according to a synergistic principle. As a result, temperature-programmed desorption mass spectrometry (TPD MS) and scanning electron microscopy have experimentally proven the presence and spatial localization of colonies of thionic bacteria and microscopic fungi in concrete structures. Correlations between the intensity of biochemical corrosion and the depth of damage to the microstructures of concrete structures have been established. Moreover, a change in the chemical composition of concrete in the workshop for the production of titanium dioxide (increased SO2 content and reduced CO2) and the formation of gypsum crystals (CaSO4 2H2O) as a result of the dissimilation of microorganisms was established. Also, in the storage room for finished products, calcium citrate crystals and a violation of the formation of calcium carbonate are formed in the surface layers of concrete. In addition, the results of the study can be used to develop antimicrobial and anticorrosive protective agents to stop the biochemical corrosion of concrete in a chemical plant