Solid State Phenomena Vol. 355

Abstract: Poor corrosion and wear resistance of metallic materials lead to deterioration of their properties and may cause failures. In fundamental, corrosion is due to the reaction of metals with their surroundings, such as moisture, salts, and air pollutants. On the other hand, wear is a surface failure because of continuous dynamic contact between the metals' surfaces and other surfaces. In this regard, surface protection such as coatings is crucial to ensure the long life of the metallic materials. Among the surface protection available, graphene-based coatings have emerged as the most researched topic due to their excellent impermeability, chemical inertness, high hardness, and flexibility. It is reported that graphene-metal and graphene-polymer nanocomposite coatings offer versatile protection against corrosion and abrasive wear. Therefore, this review presents the current state-of-the-art graphene-based nanocomposite coatings in the field of corrosion and abrasive wear resistance. This review provides significant approach of graphene-metal and graphene-polymer, as well as the future perspectives of graphene-based coatings.

Abstract: The importance of non harmful inhibitors has informed the application of drugs as an agent to mitigate corrosion of metal materials. This research reveals the inhibitive reaction and adsorption mechanism of Chlorpheniramine drug (CD), on mild steel in an HCl solution using Potentiodynamic polarization, open circuit potential and weight loss method. The CD inhibitor was proportioned into 2.5, 5, 7.5, and 10ml while molarity of HCl was varied in the proportion of 0.1, 0.5, 1.0 and 1.5M at a temperature of 298 K. The reaction showed that as the CD concentration moves to higher concentration, the efficiency of the inhibitor increases, also the higher the concentration of the acid, the higher the corrosion rate. Observation from the result revealed that CD inhibitor protected the steel from corrosion destruction. The optimum efficiency occurred as 85.80% at 10ml CD concentration. CD inhibitor obeyed Freundlich law of isotherm with the average regression value of R² = 0.9733, as R² value gets close to unity. Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectra (EDX) results also confirm strong adsorption mechanisms of CD inhibitor on the mild steel samples. Keywords: Chlorpheniramine Drug; Green Inhibitor; Open circuit potential; Potentiodynamic Polarization; Mild steel

Abstract: Siliconizing is one of the case-hardening processes used in the enhancement of some carbon-steel based material properties. Gears, rolling engineering parts, and pickling tanks produced with mild steel can offer better wear and hot-corrosion resistance characteristics through siliconizing. However, the cost of silicon hindered the wide usage of siliconized mild steel, which is the motivation for seeking remedy through processing of agro-waste materials. In this work, waste rice husk was used in the production of silicon nanoparticles using the sol-gel method. The silicon nanoparticles produced were used in the siliconizing of mild steel. The microstructure, hardness values, wear and corrosion tests were determined. The work shows that enhanced hardness values with improved corrosion and wear resistance were obtained when using waste rice husk to siliconize mild steel that can be used in the production of gears and storage tanks.

Abstract: In this study, the corrosion behavior of aluminum alloy was investigated in graphene nanoplatelet (GNP) nanofluids prepared with different surfactants. The surfactants include sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Tween 80, and Gum Arabic (GA). The corrosion properties of the alloy in the different GNP nanofluids were evaluated using potentiodynamic polarization tests at room temperature. The surface morphology of the aluminum alloy was analyzed using a scanning electron microscope coupled with an electron dispersive spectroscopy detector. The experimental results revealed that the addition of surfactants improves the resistance of the aluminum alloy to corrosion in the nanofluid. This was attributed to the adsorption of surfactants on the surface of the alloy to form a protective film layer, which reduces moisture permeability and enhances corrosion inhibition. The addition of GA was found to exhibit the highest inhibition efficiency. This was followed by Tween 80, SDS, and SDBS, which contributes the least inhibition. XRD post-corrosion analysis also reveals the presence of aluminum oxide and aluminum hydroxide phases on the surface of electrodes immersed in all the different GNP nanofluids.

Abstract: Alloy steel is known to be different from carbon steel due to the presence of the alloying element in varying compositions which is usually done for the purpose of modifying and improving the performance of the steel. However, a major problem with the alloy steel is that it usually exhibits different behavior in terms of the microstructures and the mechanical properties, especially, in sulphide environment. Thus, this study focused on the different microstructure of alloy steel and their performance in different environment with strong emphasis in sulphide environment. It was established in the study that a major problem of alloy steel in hydrogen sulphide environment is the sulphide stress cracking which is attributed to the presence of hydrogen and its absorption by the alloy steel. Hence, this study provides a potential guide and information on the capacity of the grades of alloy steel that can thrive in sulphide environment.

Abstract: It is natural to define marine corrosion in terms of the different zones in which the corrosion occurs such as atmosphere splash, tidal and sea mud etc. However, this study focused on issues affecting the marine structures, different types of corrosion and their impact on the marine steel structures as well as the machinery/equipment. Furthermore, several control measures of corrosion necessary to avert corrosion in marine environments were discussed. However, it was established that prolonged contact of marine structures with seawater would lead to corrosion as well as ruing the safety elements present. Thus, the study provides potential information to material scientists on the need for using structural steels of adequate mechanical properties.

Abstract: Thermally sprayed cermet coatings are widely used in many engineering applications to protect against wear and corrosion. In this study, three kinds of (Ti,Cr)C-based powders with 18, 25, 33 wt.% content of Ni binder were deposited onto stainless steel substrates by plasma spraying technique. The microstructure and dry sliding wear resistance of the (Ti,Cr)C-Ni coatings were investigated. The (Ti,Cr)C-Ni coatings have a heterogeneous structure composed of (Ti,Cr)C particles and Ni binder. Fracture and partial dissolution of the (Ti,Cr)C particles were found to occur during the plasma spray process. Among all the tested coatings, (Ti,Cr)C-33wt.%Ni coating exhibits lower wear rates and friction coefficients under all conditions. Worn surfaces of the coatings were analyzed using SEM to investigate the wear mechanism. With the increase in Ni content from 18 up to 33wt.%Ni wear mechanism of the (Ti,Cr)C-Ni coatings changes from abrasive to tribo-oxidation.

Abstract: The paper presents an analysis of technologies for improving the quality parameters of the surface layers of parts, which were carried out by the method of electrospark alloying (ESA) and by additional saturation of surfaces with alloying elements from special process media (STM). The technology of sulfocementation was considered. Metallographic and hardness tests after sulfocementation by ESA showed that the treated surface consists of layers: "soft", hardened and base metal. As the discharge energy increases, the thickness, microhardness and integrity of the coating increase. The presence of sulfur in STM promotes the sulfidation process. It is shown that sulfur accumulates on the surface of the metal at a depth of up to 30 μm. This zone is characterized by reduced microhardness. A strengthened layer is formed under this layer, it has an increased carbon content and high microhardness.

Abstract: In the article the microstructure and phase composition of boride coatings deposited on selected structural steels were investigated. The boride coatings were produced using pack cementation method using commercial EKABOR-2 mixture containing of 50 wt. % of new and 50 wt. % of used powder. Boride coatings were deposited on alloyed structural steels grades (PN/EN 10084 standard): 16MnCr5, 18CrNiMo7-6, 41CrAlMo7 42CrMo4. Cylindrical samples with a diameter of 30 mm and a height of 30 mm were boronized in powder at 1000°C for 2, 4 and 6 hours in an argon atmosphere. The process was carried out in an industrial CVD Bernex BPX 325S device. The microstructure was analyzed using scanning electron microscope Phenom XL equipped with EDS spectrometer. The XRD phase analysis was conducted using XTRa diffractometer (ARL). The thickness as well as phase composition was analyzed on coatings formed on each grades of steels. The most of obtained boride coatings were characterized by single-phase structure (Fe₂B). The formation of brittle FeB phase was detected only on 16MnCr5 steel grades steels.