Research of chromosilicated coatings on compact powder steels

Microstructures, chemical and phase compositions of diffusion chromosilicated coatings on powder steels 20, 45, У8 and У10 are investigated. The presence of Cr23C6 and Cr7C3 phases with up to 0,25 % Si is shown in these coatings. The distribution of diffusing chemical elements over the depth of the coating and at the interface with the matrix base is studied. Keywords: diffusion, coating, microstructure, chromosilication, powder steel, corrosion resistance [email protected]

Steel Corrosion Behavior in Light Weight Fly-Ash Based Alkali Activated Mortars

Alkali activated materials as possible sustainable alternative to cementitious binders showed competitive performances in terms of mechanical and durability properties and high temperature stability. For this reason, light weight fly-ash based mortars have already been optimized as passive fire protective coating for steel structures. However, a lack of information about the durability of these innovative systems in terms of steel corrosion resistance is still present. Thus, this study aims at investigating the durability of steel coated with a 20-mm thick light weight mortar layer in a neutral environment (tap water) and in presence of chloride-containing solution (0.2 M NaCl). In addition, the influence of pore solution chemistry and pH was discussed through electrochemical testing in leachate pore solution and NaOH aqueous solutions at different concentrations. It was found that almost complete protection ability of light weight mortar was obtained when coated steel is exposed to neutral solution for 60 days, while in presence of chlorides, steel is more susceptible to corrosion already after 40 days of exposure. In addition, the developed open porosity of the light weight mortars, it was found that pH and the chemistry of the pore solution in contact with steel strongly influenced the steel corrosion resistance.

The Influence of Ultrasonic Impact Treatment on Steel Corrosion Resistance

The influence of ultrasonic impact treatment on the corrosion resistance of 17G1S steel has been studied. It has been ascertained that the treated surface passivation effectiveness is determined by the optimal combination of ultrasonic treatment mode and choice of a corrosion inhibitor in the corrosion sites treatment. It is shown that ultrasonic impact treatment has a double action: increasing of corrosion resistance and hardening of steel.