Biodegradable magnesium alloys have recently attracted increasing interest as temporary orthopedic implant materials owing to their mechanical compatibility with bone and their ability to resorb inside the human body. However, their high corrosion rate in physiological media necessitates the development of effective surface modification strategies. In this work, the electrodeposition process was investigated using a hydroxyapatite bath (HA) and an HA bath containing Gum Arabic (GHA), applied to the three Mg-based alloys Mg-1
Aluminium alloys are known for their strength-to-weight ratio and are used in the aerospace sector. The latest developments include a bibliometric analysis to explain trends in research, major thematic changes, and networking links with the aircraft sector with respect to aluminium alloys. Aluminium alloys are still susceptible to corrosion even though they are used in large numbers, resulting in a gradual loss of mechanical integrity over time. The chrome-based systems are not new in the protection of aluminium alloys against corrosion, but their carcinogenic nature poses a risk to the environment; therefore, there is a need for alternatives. It is a state-of-the-art review paper that critically analyzes chromate-free sealing systems with emphasis on different sealing techniques for the corrosion protection of anodized aluminium alloys. Recently, sealing strategies are recognised as a requirement for the integration of barrier functionality, behaviour and stability of anodized oxide layer, where it discusses new comings in chromate-free systems, chemical inhibitors, organic–inorganic sol-gels, hybrid systems and nano-structured smart sealants. Cerium-sealed sealants have been reported to provide self-healing and corrosion resistance. At the same time, hybrid and nanocomposite sealing systems using layered double hydroxides, graphene derivatives, metal oxides, MXenes, and metal–organic frameworks are studied in terms of their potential to complement each other and increase physical barrier behaviour. This review bridges the gap between the current chromate-free sealing approaches and the state-of-the-art nanostructured smart sealants, such that a solid, self-healing, and sustainable approach to corrosion protection can be developed for an aerospace-grade anodized alloy of aluminium.
A rigorous mathematical framework is developed for electrochemical corrosion processes using coupled nonlinear ordinary differential equation (ODE) and partial differential equation (PDE) systems. The model is founded upon reaction–diffusion theory, higher-order chemical kinetics, and nonlinear feedback mechanisms that govern the spatiotemporal evolution of corrosive species concentrations. Explicit and partial differentiation, weak (variational) formulation via the Galerkin method, linear stability analysis, bifurcation theory, Lyapunov energy functionals, and asymptotic analysis are rigorously presented, establishing a complete theoretical corrosion kinetics framework commensurate with the standards expected for high publication standard. Furthermore, a fully implicit finite difference discretization employing Newton–Raphson iterative solvers and a numerical simulation validated through MATLAB simulations to confirm theoretical predictions and yield practical engineering insights across a broad spectrum of parameter regimes. Extensions to multi-species reactive transport, temperature-dependent kinetics (Arrhenius-type), pH-coupled dissolution, three-dimensional spherical geometries, and thermo-chemical energy feedback are derived to demonstrate the generality and scalability of the proposed framework. Developed a rigorous coupled nonlinear ODE–PDE reaction–diffusion framework for electrochemical corrosion kinetics in electrolytic media. Incorporated concentration-dependent diffusivity and higher-order reaction kinetics to capture complex transport–reaction interactions beyond classical linear corrosion models. Established asymptotic and Lyapunov stability conditions through linear stability analysis, bifurcation theory, and energy-based mathematical formulations. Derived weak variational formulations and implemented fully implicit finite difference discretization with Newton–Raphson nonlinear iteration for robust numerical computation. Demonstrated unconditional numerical stability and verified theoretical convergence through systematic grid-refinement and error analysis studies. Extended the model to multi-species reactive transport, Arrhenius-type thermal effects, pH-coupled dissolution, and three-dimensional spherical corrosion geometries for industrially realistic applications.
The growing demand for environmentally responsible manufacturing has accelerated the adoption of sustainable cooling and lubrication strategies for machining hardened steels. This study investigates the hard turning performance of hardened AISI D2 steel under compressed air cooling, minimum quantity lubrication (MQL), and graphene nanoplatelet-assisted MQL (GnP-MQL) using coated CBN and coated carbide cutting tools. A Face-Centered Central Composite Design (FCCD) based on Response Surface Methodology (RSM) was employed to investigate the effects of cutting speed, feed rate, and machining time on machining performance. Machining performance was evaluated in terms of flank wear, surface roughness, tool life, and wear mechanisms. Coated CBN tools exhibited superior wear resistance, with flank wear ranging from 47.06 to 219 μm compared with 61.7 to 267 μm for coated carbide tools. Among the investigated environments, GnP-MQL delivered the best performance, reducing average flank wear from 120.53 to 109.15 μm for coated CBN tools and from 178.03 to 167.45 μm for coated carbide tools while simultaneously improving surface finish and extending tool life. The minimum flank wear of 47.06 μm was achieved using a coated CBN tool under GnP-MQL at a cutting speed of 110 m/min, feed rate of 0.05 mm/rev, and machining time of 2 min. SEM and EDS analyses revealed abrasion, adhesion, built-up edge formation, edge chipping, and crater wear as the dominant wear mechanisms, with their severity substantially reduced under GnP-MQL which is attributed to the enhanced lubrication, reduced friction, and improved heat dissipation provided by graphene nanoplatelets. The findings demonstrate that GnP-MQL is an effective and environmentally sustainable cooling–lubrication strategy for improving machining performance during hard turning of AISI D2 steel with strong potential for sustainable industrial machining applications.
Metallic components, especially low-carbon steel, are susceptible to corrosion in acidic environments, causing substantial material and economic losses in industrial sectors. This study investigates the corrosion inhibition performance of ethanolic extracts obtained from the leaves and bark of Phyllanthusemblica (designated PGL and PGP, respectively) on low-carbon steel in 1 M hydrochloric acid (HCl) medium. Phytochemical screening confirmed the presence of flavonoids, phenolics, tannins, saponins, glycosides, and steroids in both extracts. Total phenolic content (TPC) and flavonoid content were quantified using the Folin–Ciocalteu and aluminium chloride colorimetric methods, respectively. Gravimetric (mass loss) measurements were complemented by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) to characterize inhibition behavior. At a maximum concentration of 1.50 g/L and 298 K, the leaf extract exhibited an inhibition efficiency of 87.1
Mandarin peel extract (MPE), an agro-waste-derived green inhibitor, was investigated for the corrosion protection of N80 carbon steel in CO2 saturated chloride-carbonate solution using gravimetric, electrochemical, adsorption, and surface characterization techniques. While citrus peel extracts have been extensively studied in acidic media, their performance under CO2 corrosion conditions representative of oilfield environments has received considerably less attention. Corrosion behaviour was evaluated by mass loss measurements, linear and potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), and adsorption isotherm analysis. The corrosion rate decreased from 0.977 to 0.005 mm year−1, corresponding to an inhibition efficiency of 99.49
Superhydrophobic surfaces, developed with inspiration from the surface micro- and nano-features of biological species such as lotus leaves, rose petals, and insect wings have gained significant interest because of their self-cleaning capabilities with excellent water repellency. This review is focused on reported research that explores the possibility of bio-inspired hierarchical micro- and nano-structured for enabling superhydrophobicity, i.e., water static contact angle more than 150° on the solid surfaces along with very low contact angle hysteresis. Over the years, several methods have been devised for making surfaces with micro- and nano-roughness features, enabling them as superhydrophobic. A comparative analysis of various fabrication techniques including chemical etching, laser ablation, plasma treatment, and hot embossing techniques is presented here in terms of scalability, reproducibility, and environmental compatibility which render them compelling candidates for many industrial applications. The surface structure formation during the fabrication process has been compared with the nature of bio-inspired features and its enablement in superhydrophobicity. The fabricated surfaces not only demonstrate strong superhydrophobicity, but they are also mechanically robust in terms of abrasion resistance, ability to with stand UV exposure and durability in harsh environment. By integrating these surface features into the functional systems, promising avenues can be explored for applications involving oil–water separation, corrosion resistance, anti-fouling, anti-icing surfaces, etc. This review, focused on the studies of surface wettability and surface roughness, also emphasizes the role of fabrication methods in tailoring the performances of designated applications.
Titanium Grade 2 has gained widespread industrial acceptance due to its superior mechanical properties, excellent corrosion resistance, and biocompatibility. Despite these advantages, its machining remains challenging because of low thermal conductivity, high chemical reactivity, and work hardening characteristics, which lead to excessive tool wear and significantly reduce the service life of cutting inserts. Consequently, improving tool life while maintaining machining performance has become a critical area of research for cost-effective manufacturing. In this research work, a Titanium rod is machined with Tungsten carbide-coated plain and honeycomb micro-textured inserts of TiCN coating. Accordingly, the usage of honeycomb micro-textured inserts resulted in lower cutting temperature values along with smooth surface roughness with minimum flank wear, which depicts good machinability. While the chip types produced by both plain and honeycomb micro-textured inserts are similar at low feed rates, an increase in feed rate resulted in a change in chip morphology for honeycomb micro-textured inserts. The chips changed from corkscrew-shaped to ribbon-like, long tubular forms, which resulted in reduced crater wear on the tool. Detailed Scanning electron microscopy and microstructural analysis of the chips showed that horizontal lines on the convex side are more prominent for curled ribbon chips as compared to other chips. While comparing with tubular chips, the corkscrew chip produced a longer, coarser tooth, leading to severe deformation on the rake face of the cutting insert. Vertical fractures are also noted at the concave side, both for corkscrew and for tubular chips.
Hybrid aluminium metal matrix composites have attracted considerable attention for high-speed tribological applications due to their superior wear resistance and lightweight characteristics. In this study, Al6061 hybrid composites reinforced with S-glass fibres (1–5 wt
This study explores the corrosion inhibition efficiency of tyrosine (Tyr), a bio-based amino acid, and its synergistic combination with chitosan (Chi) for protecting 1070 aluminum alloy in 1 M HNO3. The novelty of this work lies in the eco-friendly formulation of a dual-component, biopolymer-amino acid system that provides enhanced corrosion resistance through sustainable means. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques confirmed that Tyr acts as a mixed-type inhibitor with cathodic predominance, achieving up to 87.6
This study presents a comprehensive failure investigation of boiler water wall tubes after 15 years of continuous operation in a steam generation system rated at 142 tons per hour. The tubes made up of carbon steel ASTM A178 Grade A with an outer diameter of 50.8 mm and wall thickness of 3.2 mm, experienced multiple leak incidents leading to unplanned shutdowns. A systematic failure analysis was performed to determine the root cause and evaluate the influence of long-term service exposure on material degradation. The investigation involved visual inspection, dimensional measurement, metallographic examination, microscopic characterization using Scanning Electron Microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), elemental mapping, and X-ray diffraction (XRD) analysis of corrosion products. Results showed that the tube material possessed a normal ferrite–pearlite microstructure with no evidence of overheating, sensitization, grain coarsening, or other metallurgical defects, confirming that the failure was service induced rather than material related. Severe localized corrosion was observed on the internal tube surfaces in the form of large tubercles, pitting, wall thinning, and through wall perforation. Chemical analysis revealed strong chloride enrichment in the lower tubercle regions, with concentrations reaching about 27
Essential oils extracted from aromatic plants have attracted growing interest as biodegradable alternatives to synthetic corrosion inhibitors. In this work, Tea Tree Essential Oil extracted from Melaleuca Alternifolia was evaluated as green corrosion inhibitor for 42CD4 carbon steel in 1 M hydrochloric acid through a combined experimental and multiscale computational approach. Open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy showed that Tea Tree Essential Oil acts as a mixed–type inhibitor, whose inhibition efficiency rises with concentration to a maximum of 91.82 - systems, Monte Carlo simulations were used to quantify the adsorption behavior of each constituent on Fe (110), while molecular dynamics simulations provided radial distribution functions and diffusion coefficients derived from mean–square displacement analysis. The combined-system simulations revealed cooperative co–adsorption between oxygenated and hydrocarbon monoterpenes, rather than adsorption dominated by any single constituent, consistent with the compact film inferred from electrochemical measurements. By resolving the inhibition mechanism at the scale of the individual constituents, this study explains not only the extent of protection afforded by Tea Tree Essential Oil on 42CD4 carbon steel but its molecular origin, demonstrating how a chemically complex essential oil acts as a cooperative multi-component corrosion inhibitor.
This study investigates the failure of tapered roller bearings in a worm gearbox used in continuous pickling lines through lubricant and wear debris analysis. Kinematic viscosity, SEM-EDS, and ferrography were employed to evaluate oil degradation and wear mechanisms. The lubricant exhibited a viscosity of 361 cSt at 40 °C, exceeding the ISO VG 320 limit, indicating advanced oxidation and thickening. EDS analysis of wear particles showed iron as the main component, with traces of chromium, silicon, and oxygen, suggesting mechanical wear, contamination, and oxidative processes. Direct Reading Ferrography detected 1605 particles/mL, 72
Wire electrical discharge machining (WEDM) is increasingly considered for shaping biodegradable Mg alloys. However, discharge-induced surface damage can strongly affect both surface integrity and early-stage corrosion. This study investigates the correlation between surface integrity and in-vitro electrochemical corrosion behavior of WEDMed ZM21 Mg alloy and establishes an optimized machining window using statistical and multi-response approaches. A Taguchi L9 design was implemented by varying pulse-on time (Ton : 103–109 µs), pulse-off time (Toff : 42–52 µs), and wire feed rate (WFR : 2–6 m/min). Surface roughness (Ra) and microhardness (MH) were measured, and surface morphology was analysed using SEM and EDX. ANOVA identified Ton as the dominant factor controlling Ra, while MH exhibited a discharge-energy-dependent trend with Ton as the primary contributor. Grey relational analysis (GRA) converted the dual responses into a single surface integrity index and yielded an optimal parameter set of Ton: 106 µs, Toff: 52 µs, and WFR: 4 m/min. Electrochemical corrosion testing in simulated body fluid (0, 24, and 72 h) showed that WEDM surfaces accelerate corrosion compared with polished controls, while polishing reduced Ra and improved corrosion response. Unlike previous WEDM–Mg studies focused mainly on machinability or single-response optimization, this work integrates Ra–MH-based surface integrity optimization with time-dependent corrosion validation against polished controls. The study provides a rational, statistically optimized WEDM parameter window for fabricating ZM21 Mg alloy components with improved surface integrity for biodegradable implant applications.
Titanium-based materials are widely used in biomedical implants due to their high mechanical strength and excellent corrosion resistance. However, long-term durability is limited by passive film instability and ion release under physiological conditions. This study investigates the corrosion behaviour of Ti-15Zr-Ca3(PO4)2 composites fabricated via powder metallurgy, focusing on the influence of bioactive ceramic reinforcement on electrochemical stability. The composites were tested in simulated body fluid (SBF) phosphate-buffered saline (PBS) and 0.9
This review critically examines the applications of Couroupita guianensis Aubl (cannonball tree) plant extract in corrosion inhibition and nanoparticle synthesis. Three domains are addressed: (1) corrosion protection of metal alloys, (2) green synthesis of iron oxide nanoparticles, and (3) green synthesis of titanium oxide nanoparticles. Corrosion causes annual global economic losses of 3–4
Carbon steel corrosion in acidic media remains a major concern in oilfield, pickling, and chemical cleaning operations. In this work, a benzopyran–1,2,4-triazole hybrid derivative, methyl 1-(3-(2-amino-3-cyano-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4 H-chromen-4-yl)-4-hydroxybenzyl)-1 H-1,2,4-triazole-3-carboxylate (ATTC), was evaluated as a corrosion inhibitor for N80 carbon steel in 0.5 M H2SO4. The originality of this study lies in establishing a structure–performance relationship for this hybrid scaffold through the combined use of gravimetric and electrochemical measurements, SEM and AFM surface analyses, density functional theory, Monte Carlo sampling, and molecular dynamics simulations. The inhibition efficiency increased monotonically with ATTC concentration over the investigated range of 0.05–1.0 mM, reaching maximum values at the highest tested concentration of 1.0 mM: 97.36 K_ads=1.68× 10^6 M−1 and Δ G_ads^∘ =-45.5 kJ mol−1, indicating strong and spontaneous adsorption dominated by chemisorption, with a secondary physisorptive contribution. SEM and AFM analyses confirmed a smoother and more protected steel surface in presence of ATTC. Molecular electrostatic potential mapping, frontier-orbital distributions, Fukui dual descriptors, electron localization function analysis, and Fe–O/Fe–N radial distribution functions identified the nitrogen and oxygen atoms and the conjugated π-system as the principal adsorption and coordination regions. These results demonstrate that the high inhibition performance of ATTC originates from concentration-dependent surface coverage and strong multidentate interactions with the Fe(110) surface.
This study investigates the mechanical, tribological, and morphological properties of banana fiber and pineapple leaf fiber (PALF) as hybrid reinforced epoxy composite made with the use of the vacuum bag moulding method. Five composite ratios of banana/PALF weight 80:20, 60:40, 50: 50, 40:60 and 20:80 were made. The tensile tests showed that tensile strength and tensile modulus increased with PALF content and the highest tensile strength of 109.8 MPa and tensile modulus of 3.41 GPa were observed with the 40:60 hybrid composite. It was revealed that flexural performance can be greatly affected by fiber hybridization, and the 50:50 composite had the highest flexural strength 63.5 MPa and flexural modulus 2.82 GPa which is due to the equal distribution of loads as well as stresses between the fibers. The value of hardness improved with an increase in PALF content with increases in hardness ranging between 68 and 82 Shore D showing higher densification of the matrix. The tribological analysis revealed that the hybrid composite of 40:60 had the lowest wear rate of 2.8 × 10− 4 mm3/N.m since the fiber-matrix adhesion was improved. The energy absorption or impact testing showed that banana-rich composites had greater energy absorption, and this was mainly because of fiber pull-out. The mechanical and tribological findings were backed up by a scanning electron microscopy that showed that there were differences in interfacial bonding and fracture behavior. This research validates that banana fiber and PALF controlled hybridization substantially enhances the performance of epoxy composites in lightweight and sustainable engineering application.
The effects and properties of corrosion test on the clad area of the Al/Al2O3/SiC/Mg-SS316L composite bimetallic sheet have been investigated for CuSO4 using a solution based on H2SO4 (Copper(II) sulfate solution) at ambient temperature. A comparison of primary Al2O3 and SiC-clad surface/interface reveals some distinct variations in the intermetallics and phase development on the corroded clad-surfaces. According to obtained results, several primary α-Al and Cr based intermetallics with parent clad materials in Al2O3 or SiC combinations are identified in the microstructure, EDX, XPS, and XRD studies for the clad and its interfaces. Corrosion resistance on the open-clad surfaces the 2
Corrosion remains one of the most critical challenges in modern industry, causing severe economic losses and compromising the safety and reliability of metallic structures. Conventional corrosion inhibitors, although effective, often suffer from toxicity, limited durability, and environmental concerns. In this context, graphene and its derivatives have emerged as a new generation of corrosion inhibitors owing to their exceptional physicochemical properties, including high surface area, impermeability, mechanical strength, and tunable surface chemistry. This review provides a comprehensive overview of the electrochemical nature of corrosion and the fundamental principles of corrosion inhibition, followed by an in-depth discussion of graphene, graphene oxide (GO), and reduced graphene oxide (rGO) as corrosion-inhibiting materials. The adsorption behavior of graphene-based systems, their barrier mechanisms, and their synergistic interactions with polymers and organic inhibitors are critically examined. Experimental evidence from electrochemical and gravimetric studies demonstrates that graphene-based inhibitors can achieve inhibition efficiencies exceeding those of many conventional systems, particularly in aggressive acidic and chloride-containing environments. Practical applications in marine, oil and gas, automotive, and aerospace sectors are highlighted, along with the key challenges related to dispersion, scalability, cost, and long-term durability. Finally, emerging research directions including functionalized graphene, smart and self-healing coatings, AI-assisted material design, and sustainable synthesis routes are discussed. The review underscores the transformative potential of graphene-based corrosion inhibitors in developing high-performance, environmentally benign, and multifunctional protection systems for future infrastructure.
