Superior Corrosion Resistance Research Articles

Interface engineering in CF/Al matrix composites for enhancement in mechanical strength and anti-corrosion properties

Metal matrix composites (MMCs), renowned for their lightweight and exceptional mechanical properties, are currently in high demand. Herein, carbon fiber‑aluminum metal matrix composites (CF/Al MMCs) modified with 4 types of corrosion-barrier interface coatings (CBCs), respectively, including Ni, TiO2, ZnO, and Al2O3 were investigated, and the composites were prepared by squeeze casting technique. The effects of these CBCs on the CF/Al interface reaction and the mechanical properties and electrochemical corrosion resistance of the composites are revealed and discussed thoroughly. It is observed that T300‑carbon fiber reinforced MMCs without any CBCs exhibit low mechanical strength due to the formation of Al4C3 phase induced by strong interaction between fiber and matrix. With CBCs, the formation of Al4C3 was significantly suppressed. Comparatively, the ZnO-coated CF/Al MMCs exhibit the most remarkable enhancement in the mechanical properties with a flexural strength of 796.4 MPa and a modulus of 105.3 GPa, which are approximately 114% and 52.2% higher than those of the counterparts without CBCs, respectively. More importantly, the CF/Al MMCs with CBCs demonstrate superior chemical corrosion resistance, retaining their mechanical performance even after a 7-day immersion in salt solutions. These results provide an important guideline in interface engineering for MMCs with enhanced mechanical properties and electrochemical corrosion resistance.

Efficient and Eco-Friendly UV-Cured Polyurethane Coating: Harnessing Thiol-Yne Systems for Corrosion Protection

The UV-curable coatings have received significant attention from researchers due to their excellent advantages in corrosion protection. However, there has not been much effort made to investigate the UV-curable thiol-yne system. This project aims to prepare effective and environmentally-friendly polyurethane coatings capable of being cured by UV light using thiol-yne systems. Utilizing the chain extender derived from the glycolysis of PET, the bis(2-hydroxyethyl) terephthalate (BHET) as a glycolysis product was synthesized via the glycolysis reaction. Polyurethanes (PUYNE: yne-terminated polyurethanes and PUSH: thiol-terminatted polyurethanes) were synthesized by utilizing BHET, and by altering the quantity of the BHET, and PUX coatings were formed upon exposure to UV light. The impact of PUYNE molecular weight and the resulting amount of thiol-yne crosslinking on mechanical and thermal properties were evaluated, and corrosion resistance was examined with electrochemical impedance spectroscopy (EIS). PUX1, which had the lowest molecular weight and the highest number of thioether bonds, exhibited the superior corrosion resistance properties so that after 8 weeks of immersion in saline solution, the impedance modulus at 0.01Hz was 1.43×108 Ω.cm2. This study provides insight into the application of thiol-yne systems in forming UV-cured coatings and their protective role in preventing corrosion.

Tribo-corrosion and mechanical performance of electro-deposited nano-composite h-BN/epoxy coating

In this work, mild steel as a substrate was coated by electrodeposition in a bath mixed with nickel sulfate (NiSO4·6H2O), nickel chloride (NiCl4·6H2O), and boric acid (H3BO3) using nanocomposite cetyltrimethylammonium bromide, hBN, and epoxy with hardener. The experiments were designed using the Taguchi method through the L9 orthogonal array to reduce the number of experiments. The input parameters for the design of experiments were taken: the time (min), voltage (V), and the hBN concentration (wt-%). The coated samples were tested for their tribological, corrosion, and adhesion performance using pin-on-disc, electro-impedance spectroscopy, and cross hatch tester, respectively. The tribological results reveal that the coated sample of 3 wt-% hBN concentration at 3 mV voltage and 30-minute deposition time shows the lowest friction coefficient (∼0.42) among all the samples, indicating its superior wear resistance and corrosion resistance. Further, the same sample also outperformed the others, demonstrating the high adhesion (adhesion scale of 5 B) of coating with the substrate. Moreover, the surface was characterized using X-ray diffraction, Fourier transforms infrared, goniometer, and scanning electron microscopy.

Thermal Stability of High-Entropy Alloy Nanoparticles Evaluated by In Situ TEM Observations.

High-entropy alloy (HEA) nanoparticles (NPs) have attracted attention in several fields because of their fascinating properties. The high mechanical strength, good thermal stability, and superior corrosion resistance of HEAs, which are derived from their high configurational entropy, are attractive features. Herein, we investigated the thermal stability of FeCoNiCuPd HEA NPs on reduced graphene oxide via in situ transmission electron microscopy observations at elevated temperatures. The HEA NPs maintained their structure, size, and composition at 700 °C, and their size gradually decreased accompanied by the preferential sublimation of Cu. On the contrary, the deterioration of the monometallic Pd NPs begins at temperatures greater than 700 °C according to Ostwald ripening, which involves the migration of adatoms or mobile molecular species. Theoretical calculations revealed that the detachment of adatoms from clusters (i.e., the first step of Ostwald ripening) was suppressed in the case of HEA NPs because of the high-configuration-entropy effect.

Experimental investigation into corrosion effect on buckling and low-cycle fatigue performance of high-strength steel bars

The reinforcement in marine RC structures will inevitably be corroded under long-time erosion of chloride ions, which will weaken steel mechanical properties and then structural seismic resistance. The new metallurgical technology is adopted for manufacturing high-strength steel bars (HSSB), but that may affect the corrosion resistance of steel bars at the same time. This paper experimentally investigates the effects of corrosion on monotonic and low-cycle fatigue properties of HSSB HTRB600 and normal strength steel bars (NSB) HRB400E. The HRB400E and HTRB600 steel bars were corroded to different corrosion rates by electrochemical accelerated corrosion technique. The monotonic tensile and compressive, as well as low-cycle fatigue tests of corroded steel bars were conducted to investigate the effects of corrosion on steel mechanical properties, of which corrosion levels (0–20% target corrosion mass loss), slenderness ratios (L/D=6, 8, 10, 12) and strain amplitudes (2%, 4%) are considered. Test results show that, the corrosion morphology of steel bars under electrochemical accelerated corrosion is basically consistent with that observed under natural corrosion. Compared with uncorroded HRB400E and HTRB600 steel bars, 20% corrosion mass loss leads to 38% and 35% decrease in tensile strength, as well as 33% and 28% reduction in buckling stress, respectively. The HTRB600 steel bars present slightly superior monotonic tensile and compressive corrosion resistance than HRB400E steel bars. Corrosion obviously decreases the low-cycle fatigue (LCF) life of steel bars, resulting in reductions of 44% and 36% in LCF life at 20% corrosion mass loss for HTRB600 and HRB400E steel with a L/D of 6, respectively. Moreover, the HTRB600 steel bars present more significant corrosion degradation in total hysteretic dissipated energy, compared with HRB400E steel bars. The combined effect of corrosion and inelastic buckling further exacerbates the deterioration of LCF performance of steel bars. The corresponding deterioration models are proposed to determine the LCF life and energy dissipation capacity of corroded steel bars.

Corrosion resistance and conductivity of CrN, CrAlN, and CrTiN coatings applied to bipolar plates for proton exchange membrane fuel cells

In order to improve the corrosion resistance and conductivity of 316L stainless steel bipolar plates used for proton exchange membrane fuel cells, three Cr-containing nitride coatings were deposited on 316L stainless steel by multiarc ion plating. First, the microstructure, composition, and contact angle of the three coatings were systematically investigated. Then, electrochemical impedance spectroscopy, potentiodynamic polarization, potentiostatic polarization (PSP), and interfacial contact resistance (ICR) of the three coatings were also fully examined. The results revealed that CrN coating has the highest contact angle of 98.26°, indicating its superior hydrophobicity. Additionally, CrN coating performed the best corrosion resistance with the highest corrosion potential of 0.31 V, the lowest corrosion current density of 2.28 × 10−7 A cm−2, and the largest resistance. Furthermore, CrN coating showed the lowest current density during PSP tests and the smallest ICR value after corrosion. The superior corrosion resistance of CrN coating is mainly attributed to its decreased pore density caused by vacancylike defects and its uniform structure. This article provided evidence for the potential application of CrN coating to bipolar plates.

Synergistic Improvement of Antibacterial and Osteogenic Differentiation of Thermomechanically Processed Mg-Zr-Sr-Ce Alloy: Insights into the Role of Precipitate Evolution Supported by AIMD Simulation Study.

In the present study, we have discussed the influence of forging temperature (623 K (FT623), 723 K (FT723) and 823 K (FT823)) on microstructure and texture evolution and its implication on mechanical behavior, in vitro-in vivo biocorrosion, antibacterial response, and cytocompatibility of microalloyed Mg-Zr-Sr-Ce alloy. Phase analysis, SEM, and TEM characterization confirm the presence of Mg12Ce precipitate, and its stability was further validated by performing ab initio molecular dynamic simulation study. FT723 exhibits strengthened basal texture, higher fraction of second phases, and particle-stimulated nucleation-assisted DRX grains compared to other two specimens, resulting in superior strength with comparable ductility. FT723 also exhibits superior corrosion resistance mainly due to the strengthened basal texture and lower dislocation density. All the specimens exhibit excellent antibacterial behavior with Gram-negative E. coli, Gram-positive Staphylococcus aureus, and Pseudomonas aeruginosa bacteria. 100% reduction of bacterial growth is observed within 24 h of culture of the specimens. Cytocompatibility was determined by challenging specimen extracts with the MC3T3-E1 cell lines. FT723 specimen exhibits the highest cell proliferation and alkaline phosphatase activity (ALP) because of its superior corrosion resistance. The ability of the specimens to be used in orthopedic implant application was evaluated by in vivo study in rabbit femur. Neither tissue-related infection nor the detrimental effect surrounding the implant was confirmed from histological analysis. Significant higher bone regeneration surrounding the FT723 specimen was observed in SEM analysis and fluorochrome labeling. After 60 days, the FT723 specimen exhibits the highest bone formation, suggesting it is a suitable candidate for orthopedic implant application.

Combinatorial investigation on corrosion resistance of Ir-Ni-Ta alloys

Metallic glasses are often considered to exhibit remarkable corrosion resistance. However, the respective roles of chemical composition and amorphous structure remain unclear. In this work, we take Ir-Ni-Ta alloy system as a model system and utilize combinatorial fabrication and high-throughput characterizations to reveal the correlations between alloy composition and corrosion current density and corrosion potential. The results indicate strong correlations of corrosion current density with metal-metal bond strength and metal-oxygen bond strength, suggesting that the corrosion of the Ir-Ni-Ta metallic glasses is primarily controlled by chemical composition. However, an amorphous structure can facilitate the formation of denser passive film, and thus superimpose a positive influence on alloys that inherently exhibit corrosion resistance. Our findings would help the designing metallic glasses of superior corrosion resistance.

Development of an artificial neural network based-prediction model for bond strength of FRP bars in concrete

Fiber-reinforced polymer (FRP) bars have garnered increasing attention in recent years due to their superior corrosion resistance, offering a potential solution to the significant drawback of steel corrosion in concrete. For the widespread utilization of FRP bars in concrete structures, determining the bond strength between FRP bars and concrete is a crucial topic. This study seeks to develop a prediction model to estimate the bond strength of FRP bars in concrete, utilizing an extended dataset from 1010 pull-out tests. Initially, the study evaluates the applicability of several bond strength formulas from existing codes. Subsequently, two prediction models, namely a multivariate linear regression model and an artificial neural network (ANN) model, are introduced for estimating the bond strength of FRP bars in concrete. The results indicate that the correlation between the evaluation values of existing formulas and the experimental value is very low. This is because these formulas have not yet been updated to encompass the expanded usage scopes of FRP bars with various surface processing methods and types of concrete. While the multivariate linear regression model outperforms these formulas, its accuracy is still relatively low; in contrast, the ANN demonstrates superior performance, achieving an R^2 value for both the validation and test set of more than 0.92. The findings highlight that, when considering a broader range of applications, the ANN serves as a robust tool for accurately predicting the bond strength of FRP bars in concrete, in comparison to traditional formulas and linear regression models. This assessment approach provides engineers with a convenient, high-precision tool for designs utilizing various forms of FRP bars and diverse types of concrete in practical design scenarios

Structural behavior of one-way slabs reinforced by a combination of GFRP and steel bars: An experimental and numerical investigation

Abstract Glass- fiber-reinforced polymer (GFRP) offers a significant alternative to steel in reinforced concrete, with superior corrosion and fire resistance. Though less ductile and more brittle in stress–strain behavior than steel, it is very helpful to combine GFRP with steel reinforcement that improves the structural behavior. This research investigates the flexural characteristics of a one-way slab reinforced by a combination of GFRP and steel reinforcement. Three identical concrete slabs ((1500 × 550 × 120) mm and 43 MPa) were tested under static load with GFRP replacement ratios of (0, 20, and 40)%. The experimental data were utilized to verify a numerical model. The experimental outcomes indicated a substantial impact of the GFRP replacement ratio on the failure mode. The failure mode was flexural, flexural-shear, and shear regarding the reference slab, 20%, and 40% replacement, respectively. GFRP replacement influenced ductility and ultimate load by (9.13 and 10.7)% and (−21 and 5.0)% for replacement ratio (20 and 40)%, respectively. Based on the numerical analysis, the parametric study (considerably affected the structural response. Failure mode changed to flexural, and shear-flexural concerning (20 and 40)%, respectively. The optimum load was characterized at 40%, while max toughness and ductility were achieved at 20%.

Corrosion Behavior of Ni-Cr Alloys with Different Cr Contents in NaCl-KCl-MgCl2.

This study investigates the corrosion behavior of Ni-Cr binary alloys, including Ni-10Cr, Ni-15Cr, Ni-20Cr, Ni-25Cr, and Ni-30Cr, in a NaCl-KCl-MgCl2 molten salt mixture through gravimetric analysis. Corrosion tests were conducted at 700 °C, with the maximum immersion time reaching up to 100 h. The corrosion rate was determined by measuring the mass loss of the specimens at various time intervals. Verifying corrosion rates by combining mass loss results with the determination of element dissolution in molten salts using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Detailed examinations of the corrosion products and morphology were conducted using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Micro-area elemental analysis on the corroded surfaces was performed using an energy dispersive spectrometer (EDS), and the elemental distribution across the corrosion cross-sections was mapped. The results indicate that alloys with lower Cr content exhibit superior corrosion resistance in the NaCl-KCl-MgCl2 molten salt under an argon atmosphere compared to those with higher Cr content; no corrosion products were retained on the surfaces of the lower Cr alloys (Ni-10Cr, Ni-15Cr). For the higher Cr alloys (Ni-20Cr, Ni-25Cr, Ni-30Cr), after 20 h of corrosion, a protective layer was observed in certain areas. The formation of a stable Cr2O3 layer in the initial stages of corrosion for high-Cr content alloys, which reacts with MgO in the molten salt to form a stable MgCr2O4 spinel structure, provides additional protection for the alloys. However, over time, even under argon protection, the MgCr2O4 protective layer gradually degrades due to chloride ion infiltration and chemical reactions at high temperatures. Further analysis revealed that chloride ions play a pivotal role in the corrosion process, not only facilitating the destruction of the Cr2O3 layer on the alloy surfaces but also possibly accelerating the corrosion of the metallic matrix through electrochemical reactions. In conclusion, the corrosion behavior of Ni-Cr alloys in the NaCl-KCl-MgCl2 molten salt environment is influenced by a combination of factors, including Cr content, chloride ion activity, and the formation and degradation of protective layers. This study not only provides new insights into the corrosion resistance of Ni-Cr alloys in high-temperature molten salt environments but also offers significant theoretical support for the design and optimization of corrosion-resistant alloy materials.

Tailoring structure, morphology, and tribo-mechanical properties of HiPIMS-deposited CrxNy coatings for enhanced performance in wear and corrosion protection

During reactive sputtering of CrxNy, precise regulation of nitrogen gas is crucial to control the properties of the deposited coating. In the present work, we investigate the influence of nitrogen content on CrxNy characteristics, including morphology, crystalline structure, hardness, corrosion protection, and wear protection performances. Our findings reveal that the hexagonal Cr2N coatings, although slightly lower in hardness (19 GPa) compared to stoichiometric CrN, exhibit superior corrosion resistance with a protection efficiency of 82%, and a reduced sliding wear behavior at 1.35E-09 mm3/N/m. Conversely, stoichiometric CrN shows the highest hardness at 22.8 GPa. Using high-power impulsed magnetron sputtering as a deposition technique, we were able to design CrxNy protective coatings with desired microstructure and phase composition, enabling the production of performance-tailored CrxNy coatings suitable for a diverse range of applications.

Composition-driven superior CMAS corrosion resistance of high-entropy rare-earth disilicates

Achieving superior calcium-magnesium-aluminosilicate (CMAS) corrosion resistance in high-entropy rare-earth disilicates (HEREDs) is crucial to their applications as environmental barrier coatings in aerospace. Stimulated by the vast compositional field of HEREDs, we achieve exceptional CMAS corrosion resistance in HEREDs at elevated temperatures via a composition-driven strategy for the first time. Specifically, the equimolar 3- to 8-cation high-entropy rare-earth disilicate (3–8HERED) samples are first successfully designed and fabricated using a high-throughput pressure-less sintering technique and then their CMAS corrosion resistance up to 1773 K is evaluated. Among all the as-fabricated samples, the as-fabricated 7HERED samples are found to exhibit the best CMAS corrosion resistance. The outstanding CMAS corrosion resistance of the as-fabricated 7HERED samples is primarily attributed to pronounced sluggish diffusion induced by configurational entropy, with the synergistic effect of their chemical activity, which facilitates the formation of dense apatite protective layers. Our work provides valuable ways to design remarkable anti-CMAS corrosion high-entropy ceramics.

Investigating nano-SiC reinforced WE43 magnesium matrix surface composites

Abstract Magnesium matrix surface composites have been garnering attention due to their superior mechanical and corrosion resistance properties. An idea of facile fabrication of surface composite composed of nano-SiC reinforced WE43 matrix through friction stir processing was explored in this study. Also, the effects of tool geometries, tool rotations, and tool feeds on resultant properties were comprehensively investigated. Uniform dispersion of SiC nanoparticles within stir zone was evident. Square tool demonstrated the most promising results. Processing at 1700 rev min−1 and 60 mm min−1 with a square tool produced finest grains in surface composites exhibited exceptional microhardness (180.8 HV), nanohardness (1.867 GPa), elastic modulus (41.69 GPa), and wear resistance (0.0254 mm3 min−1). Besides it, WE43 substrates also exhibited superior mechanical properties when processed with a square tool at 800 rev min−1 and 60 mm min−1. This research opens up new possibilities for the development of reliable magnesium matrix surface composites for multifunctional applications.

Enhancing primary aqueous magnesium-air battery performance by tailoring anode texture

The mechanisms of the texture generated during the rolling process on the anodes of magnesium-air batteries remain unclear. This work systematically investigates the impact of texture on the dissolution and discharge processes of magnesium anodes using theoretical calculations combined with experiments. Results demonstrate that the ND (Normal Direction) plane of the rolled sheet contained a higher proportion of (0001) oriented grains, exhibiting excellent stability, the slowest anodic dissolution rate, superior corrosion resistance, and enhanced discharge performance. At a current density of 40 mA·cm−2, the discharge capacity and anode efficiency of the ND plane reached impressive values of 1369.86 mAh·g−1 and 61.57%. Additionally, hydrogen evolution, chunk effect, and loss of discharge during the discharge process of AZ31 anodes were quantified for the first time. Furthermore, the effect of texture on the cracking of the discharge product layer was investigated.

Experimental Investigation of Producer Gas Effects on Coated Pipelines in Biomass Downdraft Gasifier System

Abstract This research examines the performance of epoxy, ceramic, and graphene coatings on stainless steel 316 in a producer gas environment, focusing on corrosion and erosion resistance. This research aimed to identify the most effective coating for applications in harsh gasification environments. In this research, various analyses, including microstructural examination, hardness and weight measurements, FESEM analysis, and EDAX analysis, were conducted to evaluate the performance of the coatings. The producer gas was passed on to all the coated samples for a period of 100 hours. The significant findings include the superior corrosion and erosion resistance of ceramic-coated stainless steel, as evidenced by low weight fluctuations, maintained hardness levels, and elemental stability. Graphene coatings exhibit high hardness but increased porosity, raising concerns about durability, while epoxy coatings are vulnerable to gas-induced structural alterations. The inclusion rating analysis underscored the ceramic coatings' ability to preserve consistent material properties. Overall, ceramic coatings have emerged as the preferred option for gasification environments due to their structural resilience, inclusion integrity, and elemental stability. Considering the inclusion integrity, mechanical strength, weight stability, and elemental stability, ceramic-coated stainless steel 316 samples exhibit better resistance toward producer gas influence. This research contributes valuable insights for material selection in applications exposed to harsh gasification environments, emphasizing the importance of coating selection for long-term durability and performance.

Fluorosilane emulsifying chlortrifluoroethylene ternary copolymerization design towards strong adhesion, anti-corrosion, fluorescent waterborne fluorocarbon coatings for tinplate substrate

Waterborne fluorinated ethylene and vinyl ether copolymer (FEVE) coatings are progressively replacing solvent-based FEVE coatings because of their environmental friendliness. However, their practical application is limited due to the poor adhesion, waterproofing, and corrosion resistance, as well as the environmentally unfriendly nature of the small emulsifiers used. Here, a novel waterborne FEVE coating with excellent adhesion, anti-corrosion, and fluorescent properties was developed using amphiphilic fluorosilane oligomer (PFSQ) as microreactors and chlorotrifluoroethylene (CTFE), isobutyl vinyl ether (IBVE), and glycidyl methacrylate (GMA) as copolymer monomers. The introduction of fluorosilane significantly enhances the hydrophobicity of the coating (the water contact angle increased from 69.3 ± 2.4° to 131.4 ± 1.1°). The epoxy groups in the GMA units of terpolymer facilitate bonding of the coating to the substrate, enhancing the adhesion of the coating to the tinplate substrate (the lap shear strength increased from 0.47 ± 0.04 to 0.92 ± 0.01 MPa). Moreover, the interaction between the epoxy groups of GMA and the silicon hydroxyl groups of PFSQ in the synergistic network leads to the intrinsic luminescence of the coating. In addition, the coating exhibits superior corrosion resistance. The molecular structure design provides a new idea for the development of multifunctional waterborne FEVE coating.

Mechanical and electrochemical properties of (MoNbTaTiZr)1-xNx high-entropy nitride coatings

High-entropy materials possess high hardness and strong wear resistance, yet the key bottleneck for their practical applications is the poor corrosion resistance in harsh environments. In this work, the high-entropy nitride (HEN) coatings of (MoNbTaTiZr)1-xNx (x = 0-0.47) were fabricated using a hybrid direct current magnetron sputtering technique. The research focus was dedicated to the effect of nitrogen content on the microstructure, mechanical and electrochemical properties. The results showed that the as-deposited coatings exhibited a typical body-centered cubic (BCC) structure without nitrogen, while the amorphous matrix with face-centered cubic (FCC) nanocrystalline grain was observed at x = 0.17. Further increasing x in the range of 0.35-0.47 caused the appearance of polycrystalline FCC phase in structure. Compared with the MoNbTaTiZr metallic coating, the coating containing nitrogen favored the high hardness around 13.7-32.4 GPa, accompanied by excellent tolerance both against elastic and plastic deformation. Furthermore, such N-containing coatings yielded a low corrosion current density of about 10−8-10−7 A/cm2 and high electrochemical impedance of 106 Ω·cm2 in 3.5 wt.% NaCl solution, indicating the superior corrosion resistance. The reason for the enhanced electrochemical behavior could be ascribed to the spontaneous formation of protective passive layers over the coating surface, which consisted of the dominated multi-elemental oxides in chemical stability. Particularly, noted that the (MoNbTaTiZr)0.83N0.17 coating displayed the highest hardness of 32.4±2.6 GPa and H/E ratio at 0.09, together with remarkable corrosion resistance, proposing the strongest capability for harsh-environmental applications required both good anti-wear and anti-corrosion performance.

Dry wear and corrosive wear behavior of laser-cladded Co19.6Cr19.6Fe19.6Ni19.6(B13.72Si5.88)19.6Y2 and Fe43.6Ni17.4Cr9Co6B17.5Si1.5Nb5 coatings

Corrosive wear is a key factor affecting the safe operation of offshore engineering equipment. In this study, Co19.6Cr19.6Fe19.6Ni19.6(B13.72Si5.88)19.6Y2 and Fe43.6Ni17.4Cr9Co6B17.5Si1.5Nb5 coatings were prepared on the surface of 304 stainless steel using laser cladding technology. Dry wear and corrosive wear behavior of both coatings and 304 stainless steel were comparatively studied under different loads. The results show that both coatings are mainly composed of FCC solid solution, boride, and Laves phases. The average microhardness of Co19.6Cr19.6Fe19.6Ni19.6(B13.72Si5.88)19.6Y2 and Fe43.6Ni17.4Cr9Co6B17.5Si1.5Nb5 coatings are 578.6 HV0.2 and 632.5 HV0.2, respectively. The dry wear resistance of Fe43.6Ni17.4Cr9Co6B17.5Si1.5Nb5 coating is approximately 3 times that of 304 stainless steel under all friction load conditions. It can be found that the Fe43.6Ni17.4Cr9Co6B17.5Si1.5Nb5 coating with high hardness is less sensitive to friction load changes during dry wear process. In 3.5 wt% NaCl solution, the corrosive wear resistance of CoCrFeNiBSiY coating under friction loads of 30 N and 50 N is 2.68 times and 2.83 times that of 304 stainless steel, respectively. The excellent corrosive wear resistance performance of the CoCrFeNiBSiY coating is mainly attributed to its superior corrosion resistance and repassivation ability. During the corrosive wear process, a dense passivation film is formed on the surface of both coatings, which significantly reduces their friction coefficient and volume loss rate.

Quantitative Analysis of Silicon Influence and Deformation Impact on the Mechanical and Corrosion Characteristics of Nickel Aluminium Bronze (NAB) Alloy

Nickel aluminum bronze (NAB) alloy has become increasingly popular due to its superior strength, corrosion resistance, and thermal properties. This study provides an in-depth analysis of the effect of silicon and deformation percentages on the mechanical and corrosion characteristics of NAB alloy, for marine and architectural applications. The research was carried out by systematically varying the silicon percentage (0-10%) while the percentage of deformation ranges from 0-10% at ambient temperature (32 oC), and subsequent changes in its mechanical properties and corrosion resistance were observed. Mechanical properties such as ultimate tensile strength, ductility, and hardness were evaluated using standard testing methods. The results indicated a significant correlation between the silicon percentage and the mechanical properties. Specifically, an increase in the silicon percentage was found to enhance the tensile strength from 190.7 MPa to 590.8 MPa, the ductility from 23.7% to 46.9% and the hardness from 130.5 HV to 262.4 HV values of the NAB alloy. The corrosion rate of 5.49 mm/a was obtained for the reference material containing 0% Si at 0% (X0-0) deformation, while the least corrosion rate of 9.8x10-5 mm/y was recorded for 2 wt. % Si at 10% deformation (X2-5). These findings have significant implications for the use of NAB alloy in marine and architectural applications. When the silicon percentage is optimized, the mechanical strength and corrosion resistance of the alloy are enhanced, thereby improving the durability and longevity of structures made from the developed NAB alloy