Electrochemical Corrosion Properties Research Articles

Wear and corrosion properties of CP-titanium coated with Chitin–Ceramic nanocomposites

Commercial pure titanium (Cp-Ti) is widely used in many industrial and biomedical fields. However, depending on the conditions of use of Cp-Ti, it exhibits low wear and corrosion resistance, thus reducing its service life. Therefore, in this study, the cuticle of the Japanese jewel beetle (Chrysochroa rajah) was morphologically examined and duplex coatings were produced by dip coating technique on Cp-Ti to provide protection against wear and corrosion by imitating the layered structure of the Chrysochroa rajah cuticle. Duplex coated surfaces were obtained by dip coating technique with chitin as the first layer and TiO2, SiC and h-BN layers as the second layer, respectively. Electrochemical corrosion properties were investigated under Simulated Body Fluid (SBF) solution. In electrochemical corrosion tests, open circuit potential (OCP), electrochemical polarization and electrochemical impedance spectroscopy (EIS) analysis were performed. Wear tests were performed in dry and SBF solution, and tribocorrosion tests were performed in SBF solution. The chitin + h-BN duplex coated surface has the highest corrosion potential (Ecorr) of -14 mV and the lowest corrosion current density (icorr) of 1.060 × 10−9 A cm−2. In addition, chitin + h-BN duplex coated surface has the highest corrosion resistance among duplex coated surfaces with corrosion rate of 4.601 × 10−4 mpy. In the wear test results, the lowest wear rate was 0.12 ± 0.011 × 10−3 mm3/Nm in dry environment and 0.28 ± 0.017 × 10−3 mm3/Nm in SBF solution on chitin + TiO2 duplex coated surface. In addition, the highest surface hardness was obtained as 4 ± 0.28 GPa on the chitin + TiO2 duplex coated surface. As a result of the tribocorrosion tests performed in SBF solution, the highest resistance was obtained on the chitin + TiO2 duplex coated surface. The chitin layer exhibited low corrosion, wear and tribocorrosion performance. Due to the effect of different electrical charge transfer and different hardness of organic and ceramic powders used in coatings, the coated surfaces improved the electrochemical, abrasion and tribocorrosion properties of Cp-Ti.

Microstructural, Mechanical, and Corrosion Properties of AZXX Magnesium Alloy: A Review of Processing Methods

Magnesium (Mg) and its alloys are considered an ideal material for aerospace, medical, energy, and automotive purposes, because of their low density and high specific strength. Researchers are interested in AZ alloys because of their superior flow characteristics. This review makes an effort to summarise the numerous processing methods that have been adapted for use with AZXX alloy. One of the main obstacles to Mg alloys being used in their intended context is the difficulty of processing Mg and its alloys. Curiously, the homogenization process is often used in tandem with extrusion and rolling. It also gives an insight into the microstructure, mechanical (hardness, tensile, impact, fatigue, and creep), and electrochemical corrosion properties of AZXX alloys. The improvement of AZXX alloy can be attributed to the grain boundary strengthening and the second phase strengthening mechanisms. The effects of Al content and phases on properties are extensively discussed. This article summarises what has recently happened with AZXX wrought Mg alloy and offers some predictions for its future.

Influence of sintering temperature on microstructure and properties of 90W-10Ti alloy targets prepared by hot oscillating pressing

The 90W-10Ti refractory alloy was sintered by the hot oscillating pressing (HOP) and hot pressing (HP) under vacuum conditions with no contamination of oxygen and hydrogen. The effects of different sintering temperatures on the microstructure, hardness, and electrochemical corrosion properties of the resulting samples were investigated. Compared to the sample made by HP at the same temperature, the relative density, microstructure uniformity (W-W grain contiguity and βTi(W) bonding phase thickness) and properties of HOP sintering samples were significantly improved. Moreover, the sintering temperature and the activation energy were effectively reduced to inhibit grain growth by HOP. The results show that W-Ti targets with high density, fine grain size, high hardness and excellent corrosion resistance could be obtained by HOP.

Investigation of detonation spray deposited Cr3C2-NiCr cermet coatings for hard-facing applications

Austenitic stainless steels such as AISI-316 are widely employed in manufacturing engine tubular manifolds, regenerators, jet engine components, and chemical processing facilities. During operation, these components are subjected to intense corrosion and wear, which results in the replacement due to a decline in performance. Instead of total component replacement, detonation spray deposition for repair and restoration of such components can be performed to minimize the wear and corrosion of the components, which further increases the lifespan of the components. In the present study, detonation spray deposition of the Cr3C2-NiCr cermet powder on SS316 steel is evaluated. Cermet powder was chosen instead of metallic powders, because of its higher hardness, corrosion resistance and ability to resist high-temperature degradation. The generated coatings were defect-free and were having a thickness of ∼ 500 µm. Chemical composition, microstructures, Vickers microhardness, and electrochemical corrosion properties of Cr3C2-NiCr coating were evaluated. The hardness of the coating is 875 VHN and of the substrate is 210 VHN. The electrochemical corrosion of coating in 0.5 M NaC1 for 1hr has been carried out and the Photo Dynamic Polarization (PDP) curves/ Tafel plots showed.

Microstructure and Electrochemical Corrosion Properties of AlMgScZr Alloys Fabricated Using Selective Laser Melting

Microstructure and Electrochemical Corrosion Properties of AlMgScZr Alloys Fabricated Using Selective Laser Melting

Biological macrofouling and electrochemical corrosion properties of structural steel AH36 in natural seawater at Hon Tre island, Nha Trang

The biological macrofouling characteristics and electrochemical corrosion behavior of structural steel AH36 in natural seawater were studied continuously for 12 months at Hon Tre Island, Nha Trang – Vietnam. Electrochemical corrosion properties were studied using a PPGS-HHMC12 multi-channel device produced by the Institute of Chemistry, VAST. Tests were conducted at depths of 0.6 m, 1.8 m, and 3.0 m; under anti-macrofouling control, rotary movement, and under laboratory conditions as a comparison option. The results showed that macro-fouling formed and grew rapidly in both quantity, size and biomass in the next 3 months, then slowly and stably increased to about 8 months (6.06 kg.m-2). The OCP shifted to a positive potential, then reached a stable value of about -550 mV during the rest of exposure time. The corrosion current density decreased sharply from the first month to the fourth month, then reached a stable value of about 10 µA.cm-2 in next months of testing. The corrosion rate of AH36 steel in natural seawater in the field was higer than that under laboratory condition, which could be explained by the interaction of many factors such as dissolved oxygen, biofouling, water current, solar radiation

Effect of the bias-graded increment on the tribological and electrochemical corrosion properties of DLC films

Diamond-like carbon (DLC) films with bias-graded increments of 5 V, 10 V, and 20 V were prepared by adjusting the substrate bias voltage in a high-power pulsed magnetron sputtering system (HPPMS). The microstructural, mechanical, tribological, and electrochemical corrosion properties of DLC films were systematically investigated. In this work, the sp 3 content in the DLC film with a constant bias of −200 V was the highest, and the sp 3 content in the bias-graded DLC film exhibited a gradient increasing trend. Bias-graded DLC films had lower hardness, elastic modulus and residual stress than DLC film with a constant bias of −200 V. With a decrease in bias-graded increment, the ratio of hardness to elastic modulus increased. Friction and wear tests demonstrated that the wear resistance of the DLC film was related to the hardness, residual stress and ratio of the hardness to the elastic modulus. The wear rate decreased with decreasing bias-graded increment, and the DLC film with a bias-graded increment of 5 V had the lowest friction coefficient and wear rate, which were 0.077 and 6.74 × 10 −7 mm 3 /Nm, respectively. The polarization curve results revealed that the DLC film with constant bias had the highest corrosion potential and corrosion current density. As the bias-graded increment increased, the corrosion potential and corrosion current density showed an increasing trend. Combined with the electrochemical impedance spectroscopy results, the bias-graded DLC films with bias-graded increments of 5 V and 10 V exhibited better corrosion resistances. • Bias-graded DLC films were prepared in HPPMS system. • Gradient structure achieved the balance between the residual stress and the content of sp 3 . • Coating DLC film can significantly improve the tribological and electrochemical corrosion properties of the substrate.

Effects of circular beam oscillation on microstructure, mechanical and electrochemical corrosion properties of laser melting deposited Inconel 625

Circular oscillating laser was used as a heat source for additive manufacturing to fabricate Inconel 625 alloy. This study focused on the influences of the circular beam oscillation on the microstructure characteristics, tensile properties, and electrochemical corrosion performances of Inconel 625 alloy. The stirring effect of the circular beam oscillation on the molten pool interrupts the formed dendrites, and the partially fractured grains acted as nuclei to promote the growth of equiaxed grains. The average grain size of circular oscillation decreased from 111.51 to 66.49 μm. The cooling rate of the molten pool of the circular oscillation was faster, and the Refractory elements were captured by the γ matrix before Laves phase was formed, thus reducing the Laves phase content in the coating with circular beam oscillation by 50.66 %. The finer grains and lower Laves phase content reduced the crack source, and the ultimate tensile strength and yield strength of circular beam oscillation were increased by 56.95 % and 128 % respectively. The lower grain size of circular beam oscillation leads to the increase of corrosion spots, resulting in the decrease of corrosion current density by 62.3 %, which weakens the corrosion resistance.

Study of the structural, superconducting and electrochemical corrosion properties of F and Se co-doped LaOBiS2 materials

Study of the structural, superconducting and electrochemical corrosion properties of F and Se co-doped LaOBiS2 materials

Microstructure and corrosion properties of AlxCuFeNiCoCr(x = 0.5, 1.0, 1.5, 2.0) high entropy alloys with Al content

Al x CoCrFeNiCu (x = 0.5, 1.0, 1.5, 2.0) high entropy alloy was prepared by powder metallurgy method.The effect of Al content x on microstructure and corrosion properties of high entropy alloy was systematically studied. The results show that the high entropy alloy has a simple crystal structure and the distribution of components is uniform. The increase of Al content promotes the formation of the BCC structural phase. When the Al mole content is less than 1.0, the main phase is FCC and the dendrite is FCC2 and the interdendritic is FCC1. When the Al mole content is higher than 1.0, the main phase is BCC and the second phase is FCC1. The electrochemical corrosion properties of Al 1.0 CoCrFeNiCu high entropy alloy is good, and the corrosion mainly starts in the form of spot corrosion. In general, the alloy has poor resistance to nitric acid corrosion , and FCC structural phase has better resistance to nitric acid corrosion than BCC structural phase. • The increase of Al content promotes the formation of BCC structural phase in Al x CoCrFeNiCu high entropy alloy. • FCC second phase particles exist in Al x CoCrFeNiCu high entropy alloy and change with the increase of Al content. • Al 1.0 CoCrFeNiCu high entropy alloy has the best electrochemical corrosion performance. • Al x CoCrFeNiCu high entropy alloy FCC structure shows better resistance to nitric acid corrosion than BCC structure phase.

A Comparative Study of the Corrosion Electrochemical Properties and Microstructure of High-Nitrogen Steels

A Comparative Study of the Corrosion Electrochemical Properties and Microstructure of High-Nitrogen Steels

Effects of Different Scan Speeds on Microstructural and Corrosion Properties of Additively Manufactured HSLA Steels in 3.5% NaCl Solution

In automotive applications, high-strength low alloy (HSLA) steels are providing enhanced material properties, due to the high yield strength, less fragility, and lower weight, which also promotes lower fuel consumption. HSLA steels contain a small amount of carbon (under 0.2%) and also contain small amounts of alloying elements such as copper, nickel, niobium, vanadium, chromium, molybdenum and zirconium. This eliminates the toughness reducing effect of a pearlitic volume fraction, yet maintains and increases the material's strength by refining the grain size. Therefore, HSLA steels are used for structures intended to handle large amounts of stress or that need a good strength-to-weight ratio. Traditional manufacturing methods for steel (e.g., blast furnace or electric arc furnace methods) fail to provide the necessary optimization for best output in terms of performance and application. The quality of molten steel is greatly affected by scrap steel. The smelting period is longer, and the power consumption is large. In addition, these processes allow more impurities into the molten steel, which compromises the quality of the final product. However, additive manufacturing (AM) can can be used to fabricate HSLA steel components without these drawbacks. In addition, AM can provide a relatively faster process with low manufacturing costs, in comparison with traditional processing methods. Although AM has several benefits, studies shows that AM processes can result in HSLA steels with microstructural defects, such as non-homogeneity, internal cavities, inclusions, and impurities. Consequently, these microstructural features have a significant affect on the corrosion properties of AM parts as corrosion tends to initiate in defective regions. The AM processing parameters directly impact the microstructure of the fabricated part. Hence, it is important to understand the relationship between the AM processing parameters on resulting microstructural features. The present work evaluated the electrochemical corrosion properties of HSLA steels fabricated by AM via selective laser melting (SLM) under different processing conditions. The goal of the work was to investigate the role of microstructure on electrochemical corrosion in high-strength low alloy steels due to SLM processing conditions.Two types of HSLA steels, Fe 367 and Fe 398, were fabricated by AM via (SLM). Fe 398 differs from Fe 367 as it contains molybdenum and nickel. Each type was fabricated at a laser power of 100W, and scan speed of 600, 800, 100 and 1200 mm/s. The samples were exposed to 3.5% NaCl for 15 days, individually. To acquire the electrochemical corrosion data and to perform analysis, a Gamry reference 600 potentiostat/galvanostat was used. The electrochemical data were obtained by collecting the impedance spectra, and measuring the polarization resistance every 5 days. On day 15, cyclic polarization data was collected for each sample. These measurements helped to identify the localized corrosion as well as provide detailed information about the corrosion properties, such as passive layer growth, initiation and secession of pitting, and corrosion rate. The topography of the materials was observed by SEM before and after the corrosion tests. Energy Dispersive Spectroscopy (EDS) was performed on the samples to identify the chemical elements. The surface roughness was observed through confocal microscope.The Confocal and SEM images showed the change in surface microstructure and topographical properties of the samples before and after the corrosion testing. The difference in laser power and scan speed affected the microstructure and corrosion properties of the materials. As the samples were manufactured at same laser power, the scan speed was responsible for different topographical and corrosion behavior. Samples manufactured at lower scan speed showed less flaws on the surface of the materials than the samples manufactured at higher scan speed. Therefore, both Fe 398 and Fe 367 showed better surface topography at 600 mm/s and 800 mm/s. They also demonstrated significantly lower corrosion rate than the other samples. EDS identified chemical oxides and chlorides which were formed during the corrosion test. Overall, this work demonstrated that Fe 398 shows better microstructural and corrosion properties than Fe 367 at lower scan speed.

Structural and electrochemical corrosion properties of plasma-sprayed CoCrFeNiMo HEA coating in corrosive solutions

ABSTRACT A CoCrFeNiMo high-entropy alloy (HEA) coating was prepared on Ti6Al4V alloy by plasma spraying technique. The microstructure and phases of the obtained coating were analysed using an ultra-depth-of-field microscope and X-ray diffraction, respectively. The electrochemical corrosion properties of CoCrFeNiMo HEA coating in 3.5% NaCl, 0.1 M H2SO4 and 0.1 M NaOH solutions were comparatively evaluated using an electrochemical workstation, and the corrosion mechanisms were also discussed by the corrosion models. The results show that the CoCrFeNiMo HEA coating is mainly a solid solution structure of face-centered cubic, which forms mechanical bonding at the coating interface. The charge transfer resistance R ct of 597 × 1016 μA·cm–2 in 0.1 M H2SO4 solution is the highest and the corrosion current density i corr of 4.203 × 10–7 μA·cm–2 also presents the lowest among the three kinds of corrosive solutions, which shows the highest electrochemical corrosion resistance. As a result, the sequence of corrosion resistance is in 0.1 M H2SO4 solution > in 3.5% NaCl solution > in 0.1 M NaOH solution, in which the corrosion resistance is further improved by the passive film on the CoCrFeNiMo HEA coating.

Enhanced Biotribological and Anticorrosion Properties and Bioactivity of Ti6Al4V Alloys with Laser Texturing.

The poor biotribological properties and bioinertness of Ti6Al4V have restricted its application in biomedical materials. In this study, microgrooves of different widths were prepared on the surface of a Ti6Al4V alloy by laser treatment. The tribological properties under dry lubrication and simulated body fluid (SBF) lubrication conditions, the electrochemical corrosion properties in SBF solution, and the bone marrow mesenchymal stem cell (BMSC) behavior on the surfaces were systematically tested. The corresponding mechanisms were discussed. The results showed that Ti6Al4V with a microgroove width of 45 μm (Ti64-45) exhibited excellent wear resistance with decreasing wear rates of 89.79 and 85.43% under dry friction and SBF lubrication compared to the Ti64 sample, which might be due to the increase of surface microhardness. Moreover, the excellent anticorrosion performance of Ti64-45 was attributed to the grain refinement on the titanium alloy surface with a lower volume fraction ratio of β phase to α phase. In addition, the microgrooves with a width of 45 μm are more conducive to BMSC proliferation and adhesion, related to promoting cell signal transduction due to cell extrusion. These studies imply that the microgroove structures are potential for application in the medical field.

Pitting Corrosion and Mechanical Properties of Direct Current and Pulsed Reverse Current Electrodeposited Nickel-Tungsten Coatings

The electrochemical corrosion and mechanical properties of direct current and pulsed reverse current electrodeposited nickel and nickel-tungsten were investigated by using cyclic polarization measurement and nano-indentation techniques. Direct and pulsed reverse current electrodeposited nickel-tungsten coatings revealed a significant higher resistance to pitting corrosion when compared to direct and pulsed reverse current deposited nickel. Furthermore, pulsed reverse current electrodeposited nickel-tungsten displayed the most noble corrosion potential and higher corrosion resistance compared to direct current electrodeposited nickel-tungsten. This was attributed to the more nano- crystalline structure of the pulsed-reverse current deposited coatings when compared to that of the direct current electrodeposited nickel-tungsten. The average modulus for both direct and pulsed reverse current deposited nickel-tungsten were found to be similar but the average hardness of direct current deposited nickel-tungsten was slightly higher than that of pulsed reverse current deposited nickel-tungsten. This was attributed to the higher tungsten content (35 wt.%) in the direct current deposited nickel-tungsten coating compared to that (25 wt.%) in the pulsed reverse current deposited nickel-tungsten and is supported by our energy dispersive X-ray spectroscopy results.

Temporal changes of bacterial and archaeal community structure and their corrosion mechanisms in flowback and produced water from shale gas well

Superficial research on flowback and produced (FP) water from shale gas wells limit the targeted practice of corrosion protection and wastewater treatment. This study analyzes the injected fluid and the FP water at different stages in a single shale gas well with freshwater hydraulic fracturing (HF) in the Changning Shale Gas Field located in the Sichuan Basin, China. The analysis includes water-quality parameters, corrosion electrochemical properties, as well as bacterial and archaeal community structure. The results show that changes occurred at different exploration stages to the main corrosion microorganisms in the FP water, including bacteria and archaea, and their corrosion mechanisms. In the flowback stage, the genera Pseudomonas, Caenispirillum, Proteiniphilum, and Methanothermobacter were the main corrosive microbiota, whereas sulfur-cycling bacteria such as Arcobacter, Marinobacterium, and Desulfuromonas played the main corrosive role during the production period. After two months of production, the genus Arcobacter was highly enriched in the produced water, which is an atypical sulfate-reducing bacteria genus, and the corrosion rate reached 0.2518 mm/a as determined by corrosion electrochemistry. This study characterized the corrosivity of FP water intuitively using electrochemical tests and broadened the horizons of the corrosion mechanism caused by microbial succession over the shale gas exploitation and production stages. It may provide novel guidance for the treatment of FP water for recycling and corrosion protection in shale gas production.

Local Electrochemical Corrosion Properties of a Nano-SiO2/MAO Composite Coating on an AM60B-Mg Alloy.

In order to improve the corrosion resistance of the automotive AM60B-Mg alloy, a nano-SiO2/MAO composite coating was prepared on the surface of the alloy. The electrochemical properties were studied in an 80 °C corrosion environment using potentiodynamic polarization tests. Local Electrochemical Impedance Spectroscopy (LEIS) was used to study the corrosion mechanisms of coating defect zone. The microstructure and phase of the samples were observed by confocal laser microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Macroscopic electrochemical test results showed that the impedance of the nano-SiO2/MAO coating was much higher than that of the MAO coating, by about 433 times. Local electrochemical test results showed that the minimum impedance of the nano-SiO2/MAO coating was 1–2 orders of magnitude higher than the maximum impedance of the MAO coating. The defective SiO2/MAO coating still had high corrosion resistance compared to the defective MAO coating. A physical model of local corrosion mechanisms was proposed.

Investigation on the Microstructure and Electrochemical Corrosion Properties of TiB2 reinforced aluminum matrix composites

Investigation on the Microstructure and Electrochemical Corrosion Properties of TiB2 reinforced aluminum matrix composites

Improvement of Laser-Induction Hybrid Welding Processing on Electrochemical Corrosion Properties of S690QL Steel Weld Seam

Improvement of Laser-Induction Hybrid Welding Processing on Electrochemical Corrosion Properties of S690QL Steel Weld Seam

Influence of Salt-Bath Nitrocarburizing on the Electrochemical Corrosion Properties of Stainless Steels and Nickel-Based Alloys in 3.5-wt.% Sodium Chloride Solution

Influence of Salt-Bath Nitrocarburizing on the Electrochemical Corrosion Properties of Stainless Steels and Nickel-Based Alloys in 3.5-wt.% Sodium Chloride Solution