Glyceral Trinitrate: As Potential Corrosion Protector for Mild Steel in Acid Medium Along with Paint-coated Steel in a Saline Environment

The importance of mild steel lies in its industrial applications, and the fight against corrosion is very important from an ecological, economic, technical, and aesthetic view. The current study involves the use of pharmaceutical drugs namely GTN towards corrosion inhibiting reaction was examined by gravimetric and electrochemical approaches. From weight loss studies, maximum I.E (%) 94.04% reached for 60 mg/L concentration of GTN for 6 hrs immersion time. The Polarization measurements showed that the behaviour of GTN as mixed nature and surface assimilation of GTN at the superficial, such that water molecules are substituted at the solution-metal boundary. The corrosion resistance property of the studied inhibitor as coating was also evaluated in NaCl which shows better progress corrosion retardation property of coating in the saline medium. Theoretical calculations were employed using DFT to correlate with the experimental observations.

Fabrication of superhydrophobic surface with corrosion resistance via cyclic chemical etching process on aluminum substrate

Aluminum (Al) is a metal material commonly used in industry, but its surface is easily corroded. The superhydrophobic surface has great self-cleaning and anti-corrosion properties, and it is an ideal method to construct a functional aluminum surface. Here, a simple method based on cyclic chemical etching was proposed to achieve the superhydrophobic Al surface with honeycomb structures. The surface of the sample etched eight times comprised micro/nano-scale honeycomb cavities, while exhibiting a water contact angle (WCA) of 135°. After being treated with an octadecanethiol (C18H38S) methanol solution, this sample demonstrated a WCA of 153.1°. A self-cleaning test was performed on the superhydrophobic Al surface, showing the excellent self-cleaning property. Finally, the electrochemical anti-corrosion test demonstrated that the above-mentioned superhydrophobic Al surface had great corrosion resistance property. Overall, this work has enriched the theory and technology for fabricating aluminum to achieve superhydrophobic.

Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate

316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.

Enhanced Multiple Surface Properties of Biometallic Materials by Laser Microprocessing

Metallic materials have been widely used owing to their good mechanical property and high flexibility. However, there are certain limitations for practical applications such as low anti-bacterial, cell adhesion, surface wettability and corrosion resistance property. In this paper, laser microprocessing of titanium (Ti) alloy and magnesium (Mg) alloy has been conducted, respectively. The cell adhesion of Ti6Al4V alloy and Mg-Gd-Ca alloy after laser microprocessing has been investigated. The results show that MC3T3-E1 cells have been successfully adhered to the treated surface and optical density are significantly increased due to hybrid micro/nano structure. Anti-bacterial test shows that the anti-bacterial rates against E. coli of laser-treated surface was up to 72%. Meanwhile, water contact angle has been increased from 57.4° to 135.3° indicating the changing of surface wettability from hydrophilic to hydrophobic. Moreover, corrosion test of Mg-Gd-Ca alloy has been conducted, which has been significantly improved after laser microprocessing. The present work showed that laser surface microprocessing could be a promising technique for fabricating different biomedical property surfaces.

The Effects of Low Temperature Carbon Diffusion on Stainless Steel

Stainless steels along with Nickel based alloys are often selected for many applications in corrosive environments. While resistance to corrosion makes them a favorable choice, poor tribological behavior may prevent a broader use of these materials. The Kolsterising® process is a proven method for the surface hardening of these materials by the diffusion of carbon. This paper intends to highlight the improvements typically seen in key mechanical properties including resistance to galling, wear resistance, and fatigue life. Untypically, due to the nature of the process, these properties are generally improved without the usual associated reduction in corrosion resistance. Property improvements will be demonstrated using both new and existing data from Europe and North America.

Effect of Energy Density on the Microstructure and Properties of the CrFeCoNiNb High Entropy Cladded Layer

A synergistic combination of mechanical properties and corrosion resistance property is desired for most ocean engineering structural applications. In this paper, we prepared high entropy alloy (HEA) cladded layer of composition CrFeCoNiNb (atomic%). We aim to attain a balance between the mechanical property and the corrosion resistance property through adjusting the energy density. The prepared CrFeCoNiNb cladded layer with the energy density of 116.7J/mm2 exhibited excellent mechanical properties and high corrosion resistance. The improved mechanical properties are attributed to the fine grain strengthening, solid solution strengthening and dispersion strengthening. Whereas the excellent corrosion resistance is due to the fine grained BCC single phase structure and the compact passivation film. The variation of the mechanical properties and corrosion resistance with different energy densities are attribute to the phase composition. The diffraction peak area of the main phase of BCC decreases first and then increases with the increase of energy density, which is the main reason that the hardness of the cladded layer follows the similar trend. The outcome of our research suggests that the prepared CrFeCoNiNb cladded layer could be explored to realise surface strengthening of load-bearing parts in marine engineering equipment.

Influence of Shielding Gas on Microstructure and Properties of GMAW DSS2205 Welded Joints

In the present study, the microstructures and properties of DSS 2205 solid wire MIG welded samples prepared in different shielding gases (pure Ar gas, 98%Ar + 2%O2 and 98%Ar + 2%N2) were investigated for improving the weldability of DSS 2205 welded joint. The work was conducted by mechanical property tests (hardness and tensile test) and corrosion resistance property tests (immersion and electrochemical tests). The results show that adding 2%O2 into pure Ar gas as the shielding gas decreases crystal defects (faults) and improves the mechanical properties and corrosion resistance of the welded joints. Phase equilibrium and microstructural homogeneity in welded seam (WS) and heat-affected zone (HAZ) can be adjusted and the strength and corrosion resistance of welded joints increased obviously by adding 2%N2 to pure Ar gas as the shielding gas. Compared with DSS 2205 solid wire MIG welding in 98%Ar + 2%O2 mixed atmosphere, the strength and corrosion resistance of welded joints are improved more obviously in 98%Ar + 2%N2 mixed atmosphere.

Endowing magnesium with the corrosion-resistance property through cross-linking polymerized inorganic sol–gel coating

Herein, it is reported a click-chemistry based preparation strategy to highly adhesive, defect-free and low-temperature sol–gel coating for the protection of magnesium alloys.

Metallurgical and Corrosion Property of Additive Manufactured Titanium Alloy-Ti6Al4V

Additive manufacturing (AM) is an important manufacturing technology that has changed the way products are designed and manufactured. Laser Metal Deposition (LMD), an AM technology, has the capability of producing components using a 3-Dimensional CAD model, through a layer by layer formation process just like any other AM technology. In this study, the influence of the scanning speed on the corrosion property of Titanium alloy-Ti6Al4V using LMD process was investigated. The scanning speed varied between 0.02 m/s and 0.14 m/s while other processing parameters were kept constant. The electrochemical corrosion test was conducted in sodium chloride (NaCl) solution. The result revealed that the corrosion resistance property was found to increase with the scanning speed.