Volume 63 (2019): Issue 3 (November 2019)

The oxidation kinetics of depleted uranium and its low-alloy molybdenum alloys (U-2wt.%Mo, U-5wt.%Mo) were measured in a moist air (75% relative humidity) at 60 and 75 ° C. Coefficients of reaction rate equations were determined for linear oxidation kinetics. In the oxidation of depleted uranium at 75 ° C, a change in reaction kinetics from linear to exponential behaviour was observed after about 2500 hours.

The study of the deformation behavior of the pipeline material in conditions of loads and influences simulating the operation allows better estimation of the residual life of the pipelines and more accurate forecasting of the operating costs. The kinetics of deformation in 6 model environments simulating soil electrolytes was studied. Corrosion-mechanical tests were performed and the impact of the soil electrolyte chemical composition and the applied mechanical stresses on the corrosion behavior of the pipeline steel was studied. Significant increase in the corrosion activity of the soil electrolyte due to the synergistic effect of the corrosion-active components was found in the specified ratios of the ionic molar concentrations of sulphate and chloride ions (0.05 M: 0.1 M).

Biodegradable metallic implants are materials that serve as a temporary implants and scaffolds. They degrade directly in vivo and therefore eliminate need for secondary surgical intervention. They are often made of metals such as magnesium, iron, zinc and can be modified by coating with the inorganic or polymeric layer. In this work iron-based biomaterial was prepared and modified with polymeric (polyethyleneimine, PEI) layer. Its degradation behavior was studied under conditions of simulated body fluids at 37 ± 0.2 °C in the form of static immersion tests. It has been shown that the surface modification caused an acceleration of degradation of the material and also had an influence on the corrosion mechanism.

Ethanol produced from renewable resources is considered as an ecological substitute for a fossil gasoline. Ethanol blended with the fossil gasoline is able to significantly change the properties of the blended fuel as polarity, conductivity, ability to absorb air humidity and ability to dissolve a high percentage of water etc. All these properties are growing with an increasing content of ethanol and all of them can cause higher corrosivity of blended fuel. Material compatibility of metalic construction materials of the vehicle fuel system is also decreased in the environment of ethanol – gasoline blends (EGB’s). Furthermore, components of production, transport and storage equipment may be at risk of corrosion. EGB’s with an ethanol content of about 60% vol. show high corrosive aggressivness, especially if they are contaminated with water and trace amounts of ion, which may occur if proper storage, transport and production conditions are violated. Losses caused by corrosion of equipment may be prevented by using of suitable additive. Diethylenetriamine (DETA) can be used as such additive for the mild steel which is one of the most commonly used construction material. When DETA is used, it shows very high efficiency.

The beginning of the use of polyester resins for artistic work date back to the late 1950s. Initially, resins were supposed to temporarily replace and imitate traditional but more expensive sculptural materials (stone, bronze). Later, original, especially fiberglass works were created, where the laminate formed a shell connected to the internal supporting steel structure. Until now, only part of the exterior works of art made of polyester resins have been survived. Although polyester resins are considered to have good weather resistance, most exterior sculptures exhibit more or less severe defects, often resulting from neglected maintenance. The main types of defects occurring in polyester fiberglass works are presented. The most serious damage is cracks in the entire thickness of the shell, because water can easily penetrate to the internal steel structure. In the case of prolonged water penetration, the statue may collapse due to corrosion. The article presents the procedure of exploring the fiberglass sculpture from the 1950s with the introduction of suitable methods for the documentation of the state of the work. Finally, suitable restoration interventions to maximize the life of the statues are discussed.