Carbon Steel Substrate Research Articles

Corrosion behaviour of medium entropy alloy deposited on low carbon steel substrate by innovative welding method

Corrosion behaviour of medium entropy alloy deposited on low carbon steel substrate by innovative welding method

Influence of Printing Parameters on the Morphological Characteristics of Plasma Directed Energy-Deposited Stainless Steel

This study investigated the influence of printing parameters and strategies on the morphological characteristics of austenitic stainless steel beads deposited on carbon steel substrates, using plasma directed energy deposition (DED). The experimental setup varied the welding current, wire feed speed, and torch travel speed, and we analyzed three printing strategies: simple-linear, overlapping, and oscillating. Moreover, advanced 3D scanning and computational analysis were used to assess the key morphological features, including bead width and height. The results showed that the computational model developed by using parabolic assumptions accurately predicted the geometric outcomes of the overlapping beads. The oscillating printing strategy was the one that showed improved morphological uniformity and bead substrate wettability, so these features were used for multi-layer component manufacturing. The use of equivalent wavelength–amplitude values resulted in maximum combinations of bead height and width. Moreover, cost-effective carbon steel substrates were feasibly used in microstructural and elemental analyses, with the latter ones confirming the alignment of the bead composition with the wire-fed material. Overall, this study provides practical insights for optimizing plasma DED processes, thus enhancing the efficiency and quality of metal component manufacturing.

Fluorine-free superhydrophobic Ni/Mn-TiO2 composite coatings on carbon steel via one-step electrodeposition for enhanced durability and corrosion resistance

The application of superhydrophobic coatings on carbon steel (CS) surface represents an effective strategy for mitigating corrosion in these materials. This study presents the preparation of superhydrophobic Ni/Mn-TiO2 composite (SNMT) coatings on CS substrates through a facile one-step electrodeposition technique. The formation mechanism of SNMT coatings was meticulously analyzed under varying conditions of nanoparticle types and concentration levels. The inclusion of TiO2 nanoparticles, with an optimal additive concentration of 1 g, facilitated the formation of numerous low surface energy, cauliflower-like microstructures on CS interface. Surprisingly, the results indicate that SNMT coatings maintained commendable superhydrophobicity even post-exposure to superficial damages such as tape peeling, sandpaper wear, and knife-scratch, as evidenced by a static contact angle (CA) exceeding 158° and a sliding angle (SA) below 2°. Furthermore, the corrosion inhibition efficacy of SNMT coatings was quantitatively assessed via dynamic potential polarization curves in a simulated seawater environment. The results demonstrated that SNMT coatings exhibited excellent corrosion inhibition performance in simulated seawater solution, with a protection efficiency (PE) reaching 96.5%. In conclusion, superhydrophobic surfaces can effectively inhibit the penetration of corrosive liquids. The durability and robustness of such superhydrophobic surfaces advocate for their potential widespread application in enhancing the longevity and reliability of CS in corrosive environments.

Characterization of Ni-Cu multilayers deposition on low carbon steel substrate using electroplating technique

Abstract Low carbon steel is widely used in oil and gas applications. In this research, multilayers of Nickel (Ni) and Copper (Cu) were deposited on a low carbon steel substrate using the electroplating process (ELP). Initially, a layer of Ni was coated, followed by a layer of Cu. ELP was implemented using water bath containing (300 g/l) of NiSO4.6H2O, (30 g/l) of (NiCl2.6H2O), (40 g/l) of H3BO3 and (30 g/l) of (NaCN), (30 g/l) of (CuCN), (10 g/l) of (NaOH.6H2O). First bath parameters were temperature is (59 - 60 °C), current density in the range of (3-5 A/dcm2), voltage was holed at (8 V) for Ni, and temperature was between (50-51 °C), current density in the range of (1-2 A/dcm2), voltage was holed at (4 V), while the plating time (10 minutes) for both Ni and Cu. The results refer to Ni, Cu, and Ni & Cu ELP thicknesses 3, 4.77 and 6.75 μm respectively. Metallurgical tests were achieve including the micro hardness of ELP, Vickers micro hardness results showed improvement in hardness values compared, with steel substrate, and in the presence of Ni, Cu, Ni+Cu layers, 322, 581, 479, and 562 Hv respectively. The roughness was measured using surface roughness measurement device. The average surface roughness (Ra) depicted satisfying values as a result of Ni layer coating, which gave uniform surface distribution with Ra 0.363 μm. X-ray diffraction (XRD) test examinations serve as strong evidence for the presence of Ni and Cu in the internal and external finish layers, respectively. Corrosion examinations were carried out in seawater solution (3.5 g NaCl) the corrosion behavior tends to be more resistance, with layers of Ni, and Cu in sea water environment, which is considered an important criterion to increase the part life.

Dual-functionalized ORMOSIL nanoparticles to enhance superhydrophobicity of epoxy based coatings

Organically modified silica (ORMOSIL) nanoparticles bearing fluoro-octyl and glycidoxy-propyl groups were prepared by two simple methods: i) modification of silica (SiO2) nanoparticles with the corresponding organo-silanes and ii) sol-gel process involving tetraethoxy-silane in the presence of the organo-silanes. These hydrophobic ORMOSIL particles were mixed with epoxy resin/amino-based hardener in 2-propanol medium and sprayed on the surface of carbon-steel substrate. The epoxy coating containing ORMOSIL prepared by modification of SiO2 nanoparticle presented outstanding water repellence with water contact angle (WCA) of ≈ 162° and high roll-off ability of the water droplets. Furthermore, excellent adhesion to the substrate was evidenced by sandpaper abrasion and tape peeling test. The effect of the solid content in the 2-propanol dispersion on the superhydrophobicity character was investigated. It was observed that the spray dispersion with higher solid concentration resulted in better superhydrophobicity response, mechanical durability and effective self-cleaning behavior. The hierarchical structure and roughness were identified by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The coatings presented in this work are strong candidates for large scale production due to the low-cost and simplicity of the spraying technique and the economically feasibility of the involved compounds.

Parametric investigation on surface responses of TIG cladded medium carbon steel substrate with TiO2–SiC powder

The present research work consists of surface modification of a medium-carbon steel substrate with TiO2–SiC powder of the same weight percentage. A Taguchi L9 orthogonal array was used for the design of experiments. Different input process parameters, such as current (A), scan speed (mm/s) and gas flow rate (L/min), have played a significant role in controlling geometrical surface responses. The relationship between different input parameters and response surfaces (clad height, clad width) was plotted and discussed. Diagrams have been utilized to demonstrate the combined impacts of any two process factors on clad height and clad width, such as TIG current–scan speed, TIG current–gas flow rate and gas flow rate–scan speed. Experimental observations revealed that cladding input parameters have a significant influence on response surfaces. TIG current has the maximum impact on clad height. Observations showed that with the increment of current up to a certain amount clad height increased. It was also observed that with an increment of current, clad width increases. Observations revealed that as the gas flow rate rises, clad height decreases but clad width increases. It was further noted that with an increase in scan speed, clad height and clad width follow a downward trend.

Study on Initial Corrosion Behavior of Arc-thermally Spray Zn, Zn–Al, and Al–Mg Coatings Exposed in Atmospheric Environment for One-Year

AbstractThis paper presents the results of a study comparing the initial corrosion characteristics of thermal spray coatings on Zn, Zn-Al, and Al–Mg thermal spray coatings after one year atmospheric exposure tests at two atmospheric environment sites. The thermal spray coatings were obtained by electroric arc spraying of various metals onto a carbon steel substrate. Atmospheric exposure tests were also conducted for outdoor accelerated exposure tests in which test specimens were applied with artificial seawater. The corrosion properties of these spray coatings were evaluated by surface analysis, film thickness measurements, cross-sectional analysis and anodic/cathodic polarization measurement. After one year of atmospheric exposure testing, white, granular corrosion products were observed on the surface of the Zn and Zn-Al thermal spray coatings, while no significant changes were observed in the Al–Mg thermal spray coating. Similar results were obtained for the surfaces of test specimens in atmospheric exposure tests with artificial seawater. The thickness of the thermal spray coating increased for the Zn thermal spray coating, while no significant change was observed for the other thermal spray coatings. Thus, differences in corrosion behavior were observed due to the composition of the thermal spray coatings. The initial corrosion behavior of the thermal spray coatings was also investigated based on the results of coating morphology and cross-sectional elemental distribution of the coatings.

Effect of silica‐loaded polydopamine‐modified graphene oxide nanocomposites on the corrosion resistance of polyester coatings

AbstractOn the basis of the complex environment of port terminals, the corrosion resistance of coatings for accompanying metal facilities is a primary factor that needs to be considered. This study prepared polydopamine‐modified graphene oxide loaded with silicon dioxide (PGO@SiO2) functional filler, which was incorporated into polyester resin (PR) by extrusion mixing. The PGO@SiO2/PR composite coating was obtained by electrostatic spraying and high‐temperature curing. Fourier transform infrared spectroscopy, x‐ray diffraction, and other results confirmed the successful preparation of the PGO@SiO2 functional filler. In addition, contact angle, adhesion, and corrosion resistance tests were performed on the composite coating. Compared with pure PR coating, the surface hydrophobicity and adhesion of the composite coating were significantly improved compared with the pure PR coating. Furthermore, the electrochemical impedance spectroscopy of the carbon steel substrate composite coating confirmed that after immersion in salt solution, the low‐frequency impedance modulus of the composite coating could be maintained at 8.63 × 108 Ω·cm2, which was more than two orders of magnitude higher than that of the pure PR coating. Thus, PGO@SiO2 could significantly enhance the corrosion resistance of the PR coating and hinder the infiltration of corrosive media. It has broad prospects for engineering applications because of its excellent anticorrosive performance.

Revealing the microstructural evolution and mechanical response of repaired Fe–Cr–Si based alloy by directed energy deposition

This study investigates the microstructure and mechanical properties of wear-resistant hardfacing structures fabricated on an AISI 1045 carbon steel substrate using a specially designed Fe–Cr based powder for directed energy deposition (DED). Electron backscatter diffraction (EBSD) analysis reveals that the texture predominantly consists of cube rotated {001}<110> and cube {001}<110> textures, in addition to weaker Brass {112}<111> texture components. These textures contribute to the random orientations of martensitic grains and facilitate the tracing of austenite reconstruction. Notably, the as-printed samples exhibited superior yield strength (999.4 ± 86.3 MPa) and ductility (9.6 ± 2.6%) along the build direction (BD), compared to conventional samples, which demonstrated a tensile strength of 790 MPa and ductility of 2%. This improvement is primarily attributed to the hardening effects associated with a low volume fraction of retained austenite and the precipitation of Cr carbides. Comprehensive mechanical response, nanoindentation hardness profile across the interface, and microstructural analyses were conducted to confirm the feasibility of using a Fe-based hardfacing alloy for DED. The findings underscore the outstanding balance of strength and ductility exhibited by as-printed hardfacing alloy, further enhanced by its high printability, highlighting its potential in producing wear-resistant structures for repair applications.

Zn–Ni–W alloy based protective coating for enhancement of deteriorative properties in medium carbon steel substrate

Zn–Ni–W alloy based protective coating for enhancement of deteriorative properties in medium carbon steel substrate

A study integrating in-process thermal signatures, microstructure, and corrosion behaviour of AISI 316L coatings on low carbon steel substrate deposited by laser-directed energy deposition (L-DED)

Surface coating through Laser Directed Energy Deposition (L-DED) of AISI 316L on low-carbon steel was carried out by varying laser fluence. The resulting melt pool characteristics, obtained through IR pyrometer, played a significant role in evolution of the microstructure. A higher heat input resulted in an equiaxed grain structure with finer grain sizes and improved deposition quality. The quantitative phase analysis revealed the presence of a dominant austenite phase and a secondary ferrite phase, along with traces of molybdenum carbide. Corrosion analysis reveals improved resistance at a higher laser fluence, attributed to increased content of corrosion-resistant alloying elements (Mo, Cr) and predominance of the austenite phase. Electrochemical Impedance Spectroscopy (EIS) confirms a higher corrosion resistance at a higher laser fluence, supported by a significantly higher polarization resistance and presence of a duplex-structured passive film. Results indicate that moderate laser fluence levels, ranging from 5 to 7.5 kJ/cm2, accompanied by medium to high thermal signatures and moderate cooling rates, yield coatings with refined microstructures, enhanced mechanical strength, and corrosion resistance. For superior corrosion resistance, a laser fluence of 10 kJ/cm2 is recommended, although careful consideration of its potential impact on mechanical properties is advised.

Facile one-step functionalised graphene oxide-phytic acid coating towards effective wax inhibition in waxy oil transportation

Wax deposition in pipelines is a global issue during the production and transportation of oil. Recently, superhydrophilic/underwater superoleophobic coatings have garnered much attention due to their wax inhibition potential based on water film theory. Herein, carbon steel (CS) substrates were made superhydrophilic by coating phytic acid (PA) functionalised graphene oxide (GO) materials prepared by very simple process. The superhydrophilic GO-PA coatings induced the formation of a hydration layer on the surface, thus inherently showing underwater superoleophobic properties in a water-contained waxy oil system. The optimised GO-PA/CS surface possessed a water contact angle of nearly 0° and an underwater oil contact angle of ∼ 160°. This coating demonstrated up to 89.5 % enhancement in oil passing speed during the oil transportation test. This enhancement is particularly significant for reducing wax deposition in laminar and transitional flow regimes. Moreover, in the cold-finger wax deposition tests, a wax inhibition efficiency of 95.8 % was achieved with the optimised GO-PA/CS surface in the laminar flow regime. Therefore, this research provides insights into a mechanically and chemically stable GO-based coating achieved via a facile one-step functionalisation, which has not been previously reported in the literature for applications in waxy oil transportation.

Exploring the Barrier Property of High-Performance Polyurethane-Silica-Lignin Coatings on Carbon Steel

The use of lignin in anticorrosive coatings has provided efficient corrosion protection to metallic alloys.1,2 We have combined lignin-based polyurethane (PU) with silica to produce eco-friendly anticorrosive coatings with high anticorrosive performance, mechanical strength and bactericidal action.3 The PU was synthesized from methyl diphenyl diisocyanate (MDI), glycerol and lignin; the PU pre-polymer was functionalized with APTES to later form a hybrid with the polysilanol network from TEOS. The reference coating4 was prepared using 100% glycerol (PU-Si-0Lig) as the polyol source, while the other two specimens contain glycerol and 0.2 g (Pu-Si-0.2Lig) or 0.4 g (Pu-Si-0.4Lig) of lignin, keeping the predetermined proportion NCO:OH = 1.16. The incorporation of lignin into the polymer matrix led to an increase in the thermal stability (295 to 304 °C), smoothness of the coating surface (4.3 to 1.7 nm) and improvement of the coating mechanical properties, such as coating hardness (362 to 376 MPa). In addition, the lignin-containing coatings present bactericidal activity against Escherichia coli. The corrosion protection of the PU-Si-Lignin hybrid coatings deposited on carbon steel was analyzed by electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl at room temperature. The tests were conducted in a three-electrode cell, consisting of the coated carbon steel substrate as the working electrode, a platinum mesh as a counter electrode, and an Ag|AgCl|KClsat as the reference electrode. PU-Si-0Lig and PU-Si-0.2Lig present fair corrosion protection with low-frequency impedance |Zlf| values around 106 Ω.cm2 after immersion for up to 14 days. Conversely, PU-Si-0.4Lig presents |Zlf| ~ 1010 Ω.cm2, phase angle near -90 ° over seven frequency decades, and a lifespan of 100 days immersed in seawater. The equivalent electric circuit (EEC) used to fit the PU-Si-0.4Lig revealed that the EIS data of the initial 14 days can be represented by a model containing only one time constant. This means the coating has a highly capacitive behavior with insignificant water uptake in the first two weeks. Altogether, these results demonstrated the potential of PU-Si-Lig coating to be applied as an efficient anticorrosive barrier with enhanced mechanical and antibacterial properties.Acknowledgements: This work was supported by the Brazilian funding agencies CNPq, FAPESP, CAPES and PROPe UNESP.Keywords: Renewable feedstock, green coating, PU-silica, lignin, corrosion protection.(1) Harb, S. V.; Cerrutti, B. M.; Pulcinelli, S. H.; Santilli, C. V.; Hammer, P. Siloxane–PMMA Hybrid Anti-Corrosion Coatings Reinforced by Lignin. Surf Coat Technol 2015, 275, 9–16. https://doi.org/http://dx.doi.org/10.1016/j.surfcoat.2015.05.002.(2) Cao, Y.; Liu, Z.; Zheng, B.; Ou, R.; Fan, Q.; Li, L.; Guo, C.; Liu, T.; Wang, Q. Synthesis of Lignin-Based Polyols via Thiol-Ene Chemistry for High-Performance Polyurethane Anticorrosive Coating. Compos B Eng 2020, 200, 108295. https://doi.org/https://doi.org/10.1016/j.compositesb.2020.108295.(3) Alinejad, M.; Henry, C.; Nikafshar, S.; Gondaliya, A.; Bagheri, S.; Chen, N.; Singh, S. K.; Hodge, D. B.; Nejad, M. Lignin-Based Polyurethanes: Opportunities for Bio-Based Foams, Elastomers, Coatings and Adhesives. Polymers (Basel) 2019, 11 (7). https://doi.org/10.3390/polym11071202.(4) Braz, Á. G.; Pochapski, D. J.; Pulcinelli, S. H.; Santilli, C. V. Effects of Curing Temperature and Silica Content on the Structure and Properties of a Sol–Gel PU-Silica Hybrid Coating for Corrosion Protection. ACS Applied Engineering Materials 2023, 1 (7), 1739–1751. https://doi.org/10.1021/acsaenm.3c00148.

Low-Cycle Fatigue Properties of Bimetallic Steel Bar with Buckling: Energy-Based Numerical and Experimental Investigations.

A bimetallic steel bar (BSB) consisting of stainless-steel cladding and carbon steel substrate exhibits excellent corrosion resistance and good mechanical properties. The bimetallic structure of BSBs may affect their low-cycle fatigue performance, and current investigations on the above issue are limited. In this study, the low-cycle fatigue properties of bimetallic steel bars (BSBs) with inelastic buckling were investigated. Experiments and numerical studies were conducted to investigate the low-cycle fatigue capacity for BSBs, considering buckling. The buckling mode of BSBs is discussed. The hysteretic loops and energy properties of BSBs with various slenderness ratios (L/D) and fatigue strain amplitudes (εa) are investigated. With increases in the L/D and εa, the original symmetry for hysteresis loops disappears gradually, which is caused by the buckling. A predictive equation revealing the relation between the εa and fatigue life is suggested, which considers the effects of the L/D. A numerical modelling method is suggested to predict the hysteretic curves of BSBs. The effect of buckling on the stress and energy properties of BSBs is discussed through the numerical analysis of 44 models including the effects of the L/D, εa, and cladding ratios. The numerical analysis results illustrate that the hysteresis loops of BSBs with various εa values exhibit similar shapes. The increase in the cladding ratio reduces the peak stress and the dissipated energy properties of BSBs. The hysteresis loop energy density decreases by about 3% with an increase of 0.1 in the cladding ratio. It is recommended that the proportion of stainless steel inBSBs should be minimized once the corrosion resistance requirements are met.

Exploring anti-corrosion properties and rheological behaviour of tannic acid and epoxidized soybean oil-based fully bio-based epoxy thermoset resins

This research explores the physicochemical attributes of a fully bio-epoxy thermoset aimed at serving as an anti-corrosion coating for safeguarding carbon steel structures in marine environments. Throughout this investigation, various epoxy thermosets formulations, based on epoxidized soybean oil (ESO) and tannic acid (TA), were synthesized by adjusting the initial ratios of epoxide:hydroxyl groups (epoxy:OH). These formulations were subsequently applied onto carbon steel substrates and subjected to thermal curing at moderate temperatures (170 °C) to evaluate their anti-corrosion effectiveness using electrochemical impedance spectroscopy (EIS). The examination of the total impedance values derived from EIS Bode diagrams (>106 Ω) revealed a notable anti-corrosion efficacy that endured over several months of immersion in 3.5 wt% NaCl solutions. In addition to electrochemical assessment, a rheological analysis was conducted to determine the optimal curing temperature for each formulation and to track the evolution of their mechanical properties throughout the curing process. Furthermore, the progression of corrosion at the coating-metal interphase was quantified using samples featuring artificially created notches to facilitate rapid water penetration, reaching the protected surface. Moreover, cross-cut and pull-off adhesion tests were conducted on coatings cured with various epoxide:hydroxyl ratios, yielding exceptional results on carbon steel substrates. Overall, a great potential for anti-corrosion protection has been demonstrated on the developed fully bio-based coatings with tuneable mechanical properties, regarding the initial component ratio, to reach the specific requirements for specific applications.

Bidens pilosa extract as a corrosion inhibitor on 1008 carbon steel in neutral medium

The aim of this work is to evaluate the performance of Bidens pilosa extract as a corrosion inhibitor for 1008 carbon steel in a neutral medium of 0.1 M NaCl. The research has been accomplished by weight loss measurements, linear polarization resistance (Rp) monitoring and electrochemical impedance spectroscopy (EIS). Phytochemical analysis and Fourier transform infrared spectroscopy were performed to determine bioactive components and detect the main functional groups of Bidens pilosa extract, respectively. The morpholo­gical characterization of the substrate was carried out by optical microscopy (OM). Different isotherms were evaluated to understand more clearly the adsorption mechanism of the inhibitor extract molecules on the surface of the 1008 carbon steel substrate, and the best fit was obtained for the Langmuir isotherm. The results showed that the corrosion rate decreased with an increase of the concentration of the inhibitor up to 1000 ppm, reaching a maximum efficiency value of 82.9 % from gravimetric tests, and 73.1 % from the fitting of EIS data to an equivalent electric circuit. The calculated thermodynamic parameters suggested the formation of a monolayer of inhibitor molecules on the metal surface. The ΔGoads value (-22.8 kJ mol-1) determined from the Langmuir isotherm model indicated that adsorption of the inhibitor molecules on the substrate surface follows a physisorption mechanism. This research revealed that Bidens pilosa extract can be used as a corrosion inhibitor and emerges as an alternative to replace synthetic corrosion inhibitors that are harmful to health and cause damage to the environment.

Polarization-Accelerated Seawater Splash Simulation for Rapid Evaluation of Protection Performance of an Epoxy Coating on Carbon Steel.

The application of organic coatings is the most cost-effective and common method for metallic equipment toward corrosion, whose anti-corrosion property needs to be improved and evaluated in a short time. To rapidly and rationally assess the anti-corrosion property of organic coatings in the ocean splash zone, a new accelerated test was proposed. In the study, the corrosion protection property of the coating samples was measured by an improved AC-DC-AC test in a simulated seawater of 3.5 wt.% NaCl solution, a simulated ocean splash zone test and a new accelerated test combining the above two tests. The results showed that the corrosion rate of the coating samples was high in the improved AC-DC-AC test, which lost its anti-corrosion property after 24 cycles equal to 96 h. The main rapid failure reason was that the time of the water and corrosive media arriving at the carbon steel substrate under the alternating cathodic and anodic polarization with symmetrical positive and negative electric charges was shortened. The entire impedance of the coating samples was improved by about 1.6 times more than that in the initial early time in the simulated ocean splash zone test, which was caused by the damage effect from the salt spraying, drying, humidifying, salt immersion, high temperature and UVA irradiation being weaker than the enhancement effect from the post-curing process by the UVA irradiation. In the new accelerated test, the samples lost their corrosion resistance after 12 cycles equal to 288 h with the fastest failure rate. On account of the coupling process of the salt spraying, drying, humidifying, salt immersion, high temperature combined with the cathodic and anodic polarization and the UVA irradiation, the penetration and transmission rate of water and corrosive media in the coating were further accelerated, the corrosion rate on the carbon steel substrate was reinforced even larger and the destruction of the top polymer molecules was more serious. The new accelerated test showed the strongest damage-acceleration effect than that in the other two tests.

Facile spraying prepared superhydrophobic coating with self-cleaning, corrosion resistance, and increased buoyancy

The excellent mechanical properties and low-cost characteristics of carbon steel make it widely used in various facilities and equipment, but it is prone to corrosion, leading to performance degradation. Inspired by the superhydrophobic phenomenon in nature, in this paper, we used synthesized copper stearate (CuSA2) and polydimethylsiloxane (PDMS) with low surface energy properties to prepare superhydrophobic CuSA2/PDMS coatings on Q235 carbon steel substrates via a facile spray-coating method. The prepared superhydrophobic coating confirms micro-nano multi-level structures and low surface energy properties through wettability tests, surface morphology, and elemental analysis. Additionally, electrochemical impedance spectroscopy (EIS) results showed that the low-frequency modulus and charge transfer resistance of the coated substrate increased by three orders of magnitude compared to the bare Q235 carbon steel. The corrosion inhibition efficiency of the fabricated coating was 99.91 %, demonstrating significantly enhanced corrosion protection capabilities. Furthermore, due to the unique interface non-wetting and liquid-repellent properties of the surface, the coating also exhibited excellent self-cleaning and buoyancy-increasing characteristics, expanding the application areas of such materials significantly.

Post-fire mechanical properties of titanium-clad bimetallic steel after cold-forming process: Experiment and constitutive model

Titanium-clad bimetallic steel (TCBS), composed of a titanium alloy cladding layer and carbon steel substrate layer, has been proposed to mitigate the effects of corrosion and enhance the durability of steel structures. This study conducted tensile coupon test to explore the coupling effect of the cold-forming process and fire exposure on the monotonic mechanical properties of TCBS. Following the cold-forming process and fire exposure, there was no visible cracking observed in either the cladding or the metallurgical bonding layer. Test results revealed a notable enhancement in the strength properties and a decrease in the ductility of the TCBS specimens after cold forming. Moreover, the study elucidated the effects of the exposure temperature and cooling method on the stress–strain curves and fractures of TCBS corner specimens. Three different fracture sequences of the TCBS corner specimens were observed during monotonic tensile test. The key mechanical parameters were concerned in this study, which included the yield and ultimate strengths, yield and ultimate strains, elastic modulus, elongation after fracture, and section shrinkage. Then, the variation trends of key mechanical parameters were clarified. Predictive equations were developed for these parameters of the TCBS corner specimens after fire exposure. Additionally, two constitutive models were developed for the corner TCBS stress–strain curves with and without the yield plateau, enabling their use in numerical and theoretical investigations of the post-fire performance of cold-formed TCBS components.

Assessment of HVAF thermally sprayed coatings: Unraveling microstructural, electrochemical, and tribological performance using glass former Fe-Cr-Mo-Nb-B feedstock powder

In this paper the microstructural features of the glass former Fe68Cr8Mo4Nb4B16 coatings are unveiled and related to their electrochemical and tribological responses. The coating was mostly glassy with some embedded borides (M3B2, M2B-tetragonal; M being the metallic elements of the alloy) and ferrite. The tribological behavior of the HVAF coated sample, characterized by a thickness of about 200 µm, ∼6% porosity and a Vickers hardness of 357 HV0.5, was assessed in a sphere-on-plate configuration, revealing a specific wear rate of approximately 5 ×10−4 mm3∙N−1m−1. The wear mechanism was dominated by delamination caused by fragile intersplats. The corrosion resistance of HVAF coatings was evaluated in 0.6 M NaCl solution and compared with the results obtained for the crystalline Fe68Cr8Mo4Nb4B16 ingot, produced by melting in an induction furnace, and for the AISI 1020 steel substrate. The HVAF coating showed satisfactory corrosion resistance compared to the carbon steel substrate and the crystalline ingot, with the highest corrosion potential, Ecorr, values (−533 mVSCE) and the lowest corrosion current density, icorr, (10−6 A∙cm−2) followed by a clear passivation window upon anodic polarization in 0.6 M NaCl solution. Evaluations of HVAF coating showed a higher glassy content compared to the gas-atomized feedstock powders. This suggests that during spraying, certain particles were molten and experienced cooling rates adequate to inhibit crystallization, resulting in the freezing of the supercooled liquid. This phenomenon contributes to the good corrosion resistance observed in the present work and offers an opportunity to enhance the electrochemical behavior of HVAF coatings.