• Journal of Electrochemical Science and Technology
• /
• v.10 no.1
• /
• pp.29-36
• /
• 2019

Corrosion inhibition by synthesised ligand, 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (HAcETSc) and its tin(IV) complex, dichlorobutyltin(IV) 2-acetylpyridine 4-ethyl-3-thiosemicarbazone ($Sn(HAcETSc)BuCl_2$) on mild steel in 1 M hydrochloric acid (HCl) was studied using weight loss measurement, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The inhibition efficiency increases by increasing the inhibitor concentrations. The polarisation study showed that both synthesised compounds were mixed type inhibitors. The electrochemical impedance study showed that the presence of inhibitors caused the charge transfer resistance to increase as the concentration of inhibitors increased. The adsorption of these compounds on mild steel surface was found to obey Langmuir's adsorption isotherm with the free energy of adsorption ${\Delta}G{^o}_{ads}$ of -3.7 kJ/mol and -7.7 kJ/mol for ligand and complex respectively, indicating physisorption interaction between the inhibitors and 1 M HCl solution.

• Computers and Concrete
• /
• v.29 no.4
• /
• pp.237-246
• /
• 2022

The concrete quality relies on general factors like preparation technique, uniformity of the compaction, amount and appropriateness of the additives. The current article investigates the impact of a well knows amino acid, L-arginine as an additive on water requirements, setting durations and characterization of various cement samples. Compressive strength tests of reference and L-arginine added cements at age of 2, 7 and 28 days were carried out according to TS-EN 196-1. Samples were blended by incorporating various amounts of L-arginine (25 ppm, 50 ppm and 75 ppm) in the cement water mixture which were tested with Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo-gravimetric analysis (TG), scanning electron microscopy (SEM) and the energy-dispersive X-ray spectroscopy (EDS) on the 28th day. Results revealed that L-arginine does not affect the setting time, volume expansion of cement and water demands negatively; rather it imparts enhanced sustainability to the samples. It was determined that the highest value belonged to the 75L mortar with an increase of 2.6% compared to the reference sample when the compressive strengths of all mortars were compared on the 28th day. Besides, it has been observed that the development of calcium silicate hydrate or C-S-H gel, calcium hydroxide or CH and other hydrated products are associated with each other. L-arginine definitely has a contribution in the consumption of CH formed in the hydration process.

• Structural Engineering and Mechanics
• /
• v.84 no.6
• /
• pp.733-741
• /
• 2022

The amount of natural gas that is used on a worldwide scale is continuously going up. Natural gas and acidic components, such as hydrogen sulfide and carbon dioxide, cause significant corrosion damage to transmission lines and equipment in various quantities. One of the fundamental processes in natural gas processing is the separation of acid gases, among which the safety and environmental needs due to the high toxicity of hydrogen sulfide and also to prevent wear and corrosion of pipelines and gas transmission and distribution equipment, the necessity of sulfide separation Hydrogen is more essential than carbon dioxide and other compounds. Given this problem's significance, this endeavor aims to extend the lifespan of the transmission lines' pipes for gas and oil. Zinc oxide nanoparticles made from the environmentally friendly source of Allium scabriscapum have been employed to accomplish this crucial purpose. This is a simple, safe and cheap synthesis method compared to other methods, especially chemical methods. The formation of zinc oxide nanoparticles was shown by forming an absorption peak at a wavelength of about 355 nm using a spectrophotometric device and an X-ray diffraction pattern. The size and morphology of synthesized nanoparticles were determined by scanning and transmission electron microscope, and the range of size changes of nanoparticles was determined by dynamic light scattering device.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.3
• /
• pp.223-229
• /
• 2015

Surface modification is a technology to form a new surface layer and overcome the intrinsic properties of the base material by applying thermal energy or stress onto the surface of the material. The purpose of this technique is to achieve anti-corrosion, beautiful appearance, wear resistance, insulation and conductance for base materials. Surface modification techniques may include plating, chemical conversion treatment, painting, lining and surface hardening. Among which, a surface modification process using electrolytes has been investigated for a long time in connection with research on its industrial application. The technology is highly favoured by various fields because it provides not only high productivity and cost reduction opportunities, but also application availability for components with complex geometry. In this study, an electrochemical experiment was performed on the surface of 5083-O Al alloy to determine an optimal electrolyte temperature, which produces surface with excellent corrosion resistance under marine environment than the initial surface. The experiment result, the modified surface presented a significantly lower corrosion current density with increasing electrolyte temperature, except for $5^{\circ}C$ of electrolyte temperature at which premature pores was created.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.348-355
• /
• 2023

Biodiesel is known as an environmentally friendly neutral fuel, and a policy of obligatory mixing of a certain ratio is implemented on land. In this study, to verify the feasibility of using biodiesel as a ship fuel, component analysis, metal corrosion test, and storage stability test were performed on the mixing ratios of 0 %, 5 %, 10 %, and 20 % of marine diesel and biodiesel. Component analysis evaluated a total of eight factors including density, kinematic viscosity and flash point according to ISO 8217:2017 standards and the reliability of biodiesel through metal corrosion tests and storage stability tests under atmosphere temperature and harsh conditions (60 ℃) for 180 days. Results demonstrate that component analysis satisfied the ISO 8217:2017 standard in all biodiesel mixing ratios. Furthermore, as the biodiesel mixing ratio increased, the kinematic viscosity, density, and acid value increased and the sulfur content decreased. Metal corrosion rarely occurred in the case of carbon steel, iron, aluminum, and nickel, whereas in the case of copper, corrosion occurred under the influence of oxygen-rich biodiesel under the harsh conditions (60 ℃) of 20 % biodiesel mixture. As for storage stability, discoloration, sludge formation, and fuel separation were not visually confirmed.

• Corrosion Science and Technology
• /
• v.17 no.2
• /
• pp.45-53
• /
• 2018

A new 80Ti-15Ta-5Zr wt% alloy surface was protected by anodic oxidation in phosphoric acid solution. The protective oxide layer (TiO2, ZrO2 and Ta suboxides and thickness of 15.5 nm) incorporated $PO{_4}^{3-}$ ions from the solution, according to high resolution XPS spectra. The AFM analysis determined a high roughness with SEM detected pores (20 - 50 nm). The electrochemical studies of bare and anodically oxidized Ti-15Ta-5Zr alloy in Carter-Brugirard saliva of different pH values and saliva with 0.05M NaF, pointed to a nobler surface for the protected alloy, with a thicker electrodeposited oxide layer acting as a barrier against aggressive ions. The oxidized alloy significantly decreased corrosion current densities and total quantity of ions released into the oral environment in comparison with the bare one, at higher polarisation resistance and protective capacity of the electrodeposited layer. The impedance data revealed a bi-layered oxidation film formed by: a dense, compact, barrier layer in contact with the metallic substrate, decreasing the potential gradient across the metal/oxide layer/solution interface, reducing the anodic dissolution and a more permissive, porous layer in contact with the electrolyte. The open circuit potential for protected alloy shifted to nobler values, with thickening of the oxidation film signifying long-term protection.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.78-78
• /
• 2017

Pure Titanium and alloy have been widely used in dental implants and orthopedics due to their excellent mechanical properties, biocompatibility and corrosion resistance. However, due to the biologically inactive nature of Ti metal implants, it cannot bind to the living bone immediately after transplantation into the body. In order to improve the bone bonding ability of titanium implants, many attempts have been made to alter the structure, composition and chemical properties of titanium surfaces, including the deposition of bioactive coatings. The PEO method has the advantages of short experiment time and low cost. These advantages have attracted attention recently. Recently, many metal ions such as silicon, magnesium, zinc, strontium, and manganese have received attention in this field due to their impact on bone regeneration. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation and promotes bone metabolism and growth. Manganese (Mn) is an essential trace metal found in all tissues and is required for normal amino acid, lipid, protein and carbohydrate metabolism. The objective of this work was research on the corrosion behavior of Si, Zn and Mn-doped hydroxyapatite on the PEO-treated surface. Anodized alloys was prepared at 270V~300V voltage in the solution containig Zn, Si, and Mn ions. Ion release test was carried out using potentidynamic and AC impedance method in 0.9% NaCl solution. The surface characteristics of PEO treated Ti-6Al-4V alloy were investigated using XRD, FE-SEM, AFM and EDS.

• Applied Chemistry for Engineering
• /
• v.20 no.2
• /
• pp.177-185
• /
• 2009

The failure analysis of scales deposited on automotive thermostat housing has been carried out. Observations using energy dispersive spectroscopy and electron probe micro analyzer indicate that the main components of scales are some of additives of coolant used. For a detailed investigation of organic matters pyrolysis-GC/MS is employed. The result shows that the main organic component is benzoic acid and furthermore, a small amount of acetophenone, benzene and phenyl group is detected. Based on the results of failure analysis performed, the scales on automotive thermostat housing appear due to the deposition of coolant components, followed by crevice corrosion, into gap between housing and rubber horse. New accelerated test methodology, which could mimic the scale formation and the crevice corrosion on thermostat housing, is developed considering the above results. In order to reproduce the real operating conditions, the accelerating factors, i.e. temperature and humidity, are changed and programmed. The reproducibility of the accelerated test proposed is confirmed after analyzing the scales obtained from the accelerated test.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.9
• /
• pp.767-773
• /
• 2016

A Weibull statistical analysis of the mechanical properties of SiC ceramics was carried out by immersion in acidic and alkaline solutions. The heat treatment was carried out at 1373 K. The corrosion of SiC was carried out in acidic and alkaline solutions under KSL1607. The bending strength of corroded crack-healed specimens decreased 47% and 70% compared to those of uncorroded specimens in acidic and alkaline solutions, respectively. The corrosion of SiC ceramics is faster in alkaline solution than in acid solution. The scale and shape parameters were evaluated for the as-received and corroded materials, respectively. The shape parameter of the as-received material corroded in acidic and alkaline solutions was significantly more apparent in the acidic solution. Further, the heat-treated material was large in acidic solution but small in alkaline solution. The shape parameters of the as-received and heat-treated materials were smaller in both acidic and alkaline solutions.

• Journal of the Korean institute of surface engineering
• /
• v.50 no.6
• /
• pp.531-535
• /
• 2017

Enormous amount of waste oyster-shell (OS) has a major disposal problem in coastal regions. OSs have attracted much attention for recycling, because these are mainly composed of calcium carbonate with rare impurities. In this study, we demonstrate the calcareous deposit films on steel plate by using OSs on the basic of cathodic protection technique. The composition of the OSs was analyzed by wavelength dispersive X-ray fluorescence spectrometer. Carbon dioxide gas was pumped into distilled water to make carbonic acid solution for dissolution of OS. The calcareous deposit was characterized by second electron microscope (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction. Corrosion rates were estimated by measurements of anodic polarization and immersion test. It is confirmed that calcareous deposits on steel plate are formed under all condition of cathodic protection by using waste OS from the SEM and EDX results. Calcareous deposits on steel by OS provide good corrosion resistance by acting as a barrier to oxygen supply to the steel surface.