ДОЦІЛЬНІСТЬ ЗАСТОСУВАННЯ СТЕРИЧНО УСКЛАДНЕНИХ АЦЕНАФТЕНОВИХ СПОЛУК У СКЛАДІ ПРОТИКОРОЗІЙНОЇ КОМПОЗИЦІЇ

Goal. Synthesis and study of the effect of the inhibitory component – sterically complicated acenaphthene compounds – on the effectiveness of the protective composition to prevent corrosion of metal products during the period of temporary preservation.Method. Coke-chemical acenaphthylene was isolated from the absorbing and anthracene fractions of coal tar, the bromination of which led to 1,2-dibromocenaphthene. Subsequent alkylation of azine bases with 1,2-dibromacenaphthene yielded a number of sterically complex acenaphthene compounds. In the conditions of simulation aggressiveness of NSS environment the influence of synthesized additives on efficiency of anticorrosive composition is investigated (ISO 9227:2017). Research methods: chromatography, synthesis, elemental analysis, IR spectroscopy, corrosion tests.Results. On the basis of low-demand, available and inexpensive components of coke production, a number of substances with high anti-corrosion properties were synthesized – Quaternary azine salts with acenaphthene fragment. It was determined that the greatest resistance to the destructive effects of corrosive NSS environment according to the results of accelerated atmospheric corrosion tests was demonstrated by a composite coating containing an inhibitory additive – 1-(2-bromo-1,2-dihydroacenaphthylen-1-yl) quinoline bromide. The dominant role of the structure of the inhibitory additive on the manifestation of anticorrosive properties of the protective composition is shown. The influence of the ratio of components of paints and varnishes on their technological and anti-corrosion properties has been studied. The obtained results allow to create a new formulation of the domestic competitive protective composition to prevent corrosion of the metal for the period of temporary preservation.Scientific novelty. The role of 1,2-dibromacenaphthene as a promising alkylating agent in the synthesis of inhibitory additives - sterically complicated acenaphthene compounds has been determined.Practical significance. The optimal content of inhibitory components – Quaternary azine salts with acenaphthene fragment – for the development of a formulation of an effective anti-corrosion composition for the period of temporary preservation of metal products.

The Microstructure and Property of a Titanium-Carbon Steel Clad Plate Prepared Using Explosive Welding

The microstructure and properties of pure titanium (Ti)-carbon steel clad plate prepared using explosive welding were characterized. The bonding of the welding interface was inspected using C-scanning imaging technique. The microstructure and composition of the clad were characterized with optical microscopy and scanning electron microscopy. Mechanical and corrosion properties of the clad plate were investigated using tensile test, shearing test, and potentiodynamic polarization measurement. The results show that the pure titanium and carbon steel plate are joined successfully without visible defects. The interface wave is uniform. SEM observation and EDS analyses show that some melt blocks distribute at the interface waves vortices. Hardness testes results show that after heat treating, the hardness values in the titanium layer of the clad plate are similar to the original titanium plate, whereas the values at carbon steel layer increase from the interface to 300 μm away. Tensile and shearing test results indicate that the mechanical properties of the clad meet the requirements of ASTM B898 standard. Corrosion test shows that the Ecorr of the clad plate is more positive, and icorr is 1 order of magnitude lower compared to carbon steel material, suggesting that the corrosion resistance of clad plate is better than that of carbon steel material. These results suggest that the clad plate has good bonding quality and properties to meet the processing requirement and can be safely applicable in the petrochemical field.

Improvement of corrosion resistance of maraging steel manufactured by selective laser melting through Intercritical heat-treatment

Existing studies suggest that martensite-to-austenite reversion can increase the overall mechanical strength of maraging steel. Their effect on corrosion properties, however, is unclear. Selective laser melted (SLM) specimens were tempered near austenite finish temperatures to investigate the electrochemical effect of reversed austenite. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to characterize their microstructure. To define and test pitting performance, potentiodynamic polarization and open-circuit potential were performed in a 3.5 wt. % NaCl solution. The reversed austenite precipitated mainly along the martensite lath boundaries during the Intercritical heat treatment at 720°C. The nucleation of reversed austenite is allowed by the local Ni enrichment caused by the dissolution of intermetallic particles. As a result, the tempered 720°C specimens reported a higher pitting potential, lowest corrosion current density, and lowest corrosion rate than the as-printed, aged, and homogenized specimens. No investigations have been performed to date that demonstrate the impact of austenite reversion on the corrosion susceptibility of SLM maraging steel. Other than being nobler, austenite is lighter than martensite due to reduced precipitant density, accounting for fewer galvanic cells and a lower corrosion rate.

Corrosion Resistance, Evaluation Methods, and Surface Treatments of Stainless Steels

Stainless steels are widely recognized and find applications in many engineering industries and companies due to their excellent properties including high resistance to corrosion as a result of their minimum 10.5% chromium content, exceptional strength and durability, temperature resistance, high recyclability, and easy formability. In the present book chapter, the basic concepts of stainless steel including its applications, classifications, and corrosion properties will first be discussed. Thereafter, their corrosion behaviour will then be explained. The various methods by which the corrosion resistance behaviour can be significantly improved including surface treatments such as coatings/electrodepositions, alloying, mechanical treatment, and others will be discussed in detail.

Mechanical and Corrosion Behavior of Friction Stir Welded AA 6063 Alloy

Friction stir welding (FSW) is considered to be the most significant development in solid state metal joining processes. This joining technique is energy efficient, environmentally friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. The project aims to join Aluminum 6063 alloy plates by FSW and emphasize the (1) mechanisms responsible for the formation of welds without any defects, microstructural refinement, and (2) effects of FSW parameters on resultant microstructure, mechanical, and corrosion properties.