ABSTRACT Phase change materials (PCMs) are extensively explored for thermal energy storage (TES) applications. While paraffin wax is the most widely studied organic PCM, non‐paraffinic bio‐based fatty acids offer a more sustainable alternative. This study systematically evaluates seven palm fatty acids: caprylic, capric, lauric, myristic, palmitic, stearic, and oleic acids, focusing on thermal stability, reliability, and metal compatibility, compared with paraffin wax. In addition to standard thermal characterization, a heat absorption‐release test was performed to assess heat storage performance. PCM properties were analyzed before and after two thermal reliability assessments: thermal treatment (up to 700 h) and thermal cycling (up to 350 cycles). Differential scanning calorimetry (DSC) determined phase change temperature, latent heat, and specific heat capacity ( C p ), while thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) assessed thermal and chemical stability. The palm fatty acids exhibited slight variations in phase change temperature (0.03°C–3.6°C) and moderate melting latent heat reductions (−3.2% to −6.2% after thermal treatment, −7.5% to −13.8% after thermal cycling), comparable to paraffin wax (0.04°C–1.32°C, −7.0%, −10.3%, respectively). Similar to paraffin wax, changes in C p , heat storage performance, TGA, and FTIR results further confirmed the thermal reliability of palm fatty acids. Twelve‐week corrosion tests showed decreasing corrosion rates with time and confirmed the compatibility of all tested PCMs with stainless steel, aluminum, copper, and brass, with most corrosion rates remaining below the critical threshold for long‐term use. Overall, palm fatty acids demonstrate high thermal reliability, stability, and metal compatibility comparable to paraffin wax, establishing them as sustainable bio‐based PCMs for long‐term TES applications.

Biocorrosion studies on borated and non-borated 304L stainless steel using Bacillus subtilis SNF-1, a bacterial isolate from SNF pool.

Effects of corrosion rate, mechanical properties, toxicity, and bone healing towards different surface modification of biodegradable metallic: A systematic review

A novel PINN-STAN model for predicting corrosion rate in subsea oil and gas pipelines

Hybrid LSTM–dense neural network for accurate corrosion rate prediction in friction stir welded flange joints

Fe/Zn composite with high strength-ductility, large-area galvanic corrosion, antibacterial, angiogenic, and osteointegrative capabilities for biodegradable bone-fixation applications.

Influence of initial cell counts on the microbiologically influenced corrosion of L245N steel in shale gas environments.

Limestone corrosion and coastal karst cave (flank margin cave) enlargement are closely related by the mixing zone between meteoric and seawater, yet quantitative data on corrosion rates in these environments remain scarce. Recent speleodiving exploration in flanking margin caves in Mallorca revealed numerous submerged cavities with different haloclines between 0 and 25 m below m.s.l. To investigate rock-decay mechanisms along these haloclines, exposure trials were conducted in Cova de sa Gleda. Three sets of water-loss rock tablets (WLRT), composed of bioclastic calcarenite limestone and crystalline aragonite (aragonite crystal aggregates), were deployed along a water-column depth profile ranging from 5 to 16 m. After 749 exposure days, tablets were explored by SEM and XRD. Differences in mass show that calcarenite tablets lost an average of 1.89% of their initial mass, while aragonite tablets have lost 8.05%. Corrosion rates varied along haloclines: at 5 m depth (10 to 16 PSU), rates were 3.10% for calcarenites and 11.08% for aragonite; at 10 m (19 to 29 PSU), corrosion increased respectively to 10.8% and 17.93%; at 16 m (>35 PSU, seawater), corrosion decreased to 1.97% and 3.48%, respectively. These haloclines coincide with the height position of notches and other observable corrosion features within the cave. Consequently, these corrosion features present along the cave can be interpreted as proxies of the former position of the groundwater mixing zone.

Purpose The purpose of this study is to investigate the susceptibility of L80, and other steels with 1% Cr, 3% Cr and 9% Cr, to stress corrosion cracking (SCC), pitting, crevice and stress concentration effect at the existing conditions of an oil reservoir. Design/methodology/approach The 4-points bent beam specimens were employed in the experimental works. The experimental works were performed at 82°C in a simulated environment that contains CO2 and Cl−. The effect of stress concentration on corrosion rate was confirmed by the novel circumferential notched tensile (CNT) specimen approach. Findings The results indicate that these steel grades are not susceptible to SCC in the given condition, and are promising materials for the application. The L80, 1% Cr and 3% Cr steels were attacked by pitting and crevice corrosion, while the 9% Cr steel was insignificantly affected, presumably due to its higher Cr, Mo and Ni contents. The local corrosion concentrated on sites that have high stress concentration. The CNT specimens confirmed the effect of stress concentration on promoting the local corrosion. Originality/value The study provides an essential insight into the susceptibility of downhole tubular to SCC for L80, 1% Cr, 3% Cr and 9% Cr steels in simulated reservoirs environment that contains CO2 and Cl−. A novel fracture mechanics approach using the CNT specimen method was introduced in investigating the effect of stress intensity on corrosion rate.

The geometry of metal components is an important factor influencing corrosion behavior, particularly localized corrosion. This study aims to analyze the effect of geometric variations on the corrosion rate of carbon steel through a simulated laboratory experimental approach. Carbon steel specimens were fabricated with three different geometries, namely flat surface, sharp-edged surface, and crevice geometry. Corrosion testing was conducted using immersion and potentiodynamic polarization methods in a 3.5% NaCl solution. The analyzed parameters included mass loss corrosion rate, corrosion potential, and corrosion current density. The results showed that crevice specimens exhibited the highest corrosion rate, followed by sharp-edged specimens, while flat surfaces demonstrated the best corrosion resistance. This behavior is attributed to the formation of differential aeration cells and non-uniform current density distribution caused by geometric variations. These findings highlight the importance of considering geometric design in corrosion mitigation strategies for metal components.

CoCuNiTi HEACs reinforced by different diamond contents were prepared on the surface of 45 steel substrate by laser cladding. Their phase composition, microstructure, elemental composition, and wear/corrosion resistance were investigated using XRD, OM, SEM, EDS, a friction and wear testing machine, and an electrochemical workstation, respectively. The results show that after adding diamond, the phase composition of the sample transforms from the original dual-phase structure of the FCC main phase and BCC to the dual-phase structure of the BCC main phase and FCC. With an increase in the diamond content, the diffraction peak intensity of the alloy phases first increases and then decreases. This behavior is related to the significant enhancement of the alloy phase crystallinity with low diamond addition and the intensified crystal lattice distortion caused by excessive diamond addition. The CoCuNiTi + x Diamond (C) (x = 0, 0.5, and 1.0 wt.%) high-entropy alloys have a dendritic structure. After the addition of diamond, no hole defects were observed in the microstructure, and the dendritic structure was significantly refined. Ti and C are enriched in the primary phase, Cu is enriched in the interdendrite regions, and Co exhibits the highest concentration in the dendrite regions. The segregation coefficients of Ni in all three alloys are relatively small. As the diamond content increases, the friction coefficient of the samples decreases significantly. The 1 wt.% diamond sample exhibits the best wear resistance, primarily owing to the combined effects of superhard phase strengthening, solid solution strengthening, and fine grain strengthening resulting from diamond addition. The sample with 0.5 wt.% diamond addition has the lowest self-corrosion current density, highest polarization resistance, and lowest annual corrosion rate, indicating the best corrosion resistance. This performance is mainly attributed to the refinement of the microstructure, reduction in defects, and formation of a dense passivation film caused by the addition of a small amount of diamond.

Titanium and its alloy Ti6Al4V have gained attention as advanced biomaterials in healthcare due to the presence of native amorphous titanium oxide layer on their surface. This inherent amorphous layer with thickness restricted to 3-7 nm imparts improve biocompatibility and corrosion resistance to the material. However, this limited thickness constrains its functional performance. This work is aimed at improving the functionality of Ti6Al4V by creating an oxide layer of suitable thickness on its surface through controlled heat treatment. Samples were oxidized at three different temperatures, 400 ºC, 600 ºC and 800 ºC for 1h and alteration in morphology, oxygen content, crystallization of oxide layer, surface energy, surface roughness and micro-harness of the samples were investigated. The electrochemical analysis revealed a systematic lowering in corrosion rate with increasing temperature. Notably, the corrosion rate of the sample heated at 800 ºC was 0.52 mil/y that is 1/4th times lower to pristine sample (2.04 mil/y). Tribology analysis showed a significant enhancement in wear resistance. The wear rate of pristine Ti6Al4V (7.56 x 10-3 mm3/Nm) reduced by two-orders for sample heat treated at 800 ºC (9.59 x 10-5 mm3/Nm) when tested against a stainless steel counterpart. Further, samples subjected to higher thermal oxidation exhibited superior bioactivity, as evidenced by increased apatite growth and calcium to phosphorus ratio closer to optimum value reported in litrature. The improved performance of thermally oxidized sample is attributed to an increase in rutile phase of crystalline titanium oxide on Ti6Al4V surface post heat treatment.

In this study, a novel approach is used to study the effect of D-gun deposited 86WC-10Co-4Cr cermet coating of 100 µm thickness on the 1.2709 tool steel substrate fabricated by the Selective Laser Melting process. Results are compared between as-built, heat treated (500°C, 750°C, 1000°C for 6 h), and coated samples. The thermomechanical study using dilatometry analysis revealed lowest average coefficient of thermal expansion in coated sample than heat treated and as-built samples. The as-built microstructure exposed non-equiaxed formation with elongated columnar boundaries along the build direction with lack of fusion and porosity defects which was further refined through subsequent heat treatment process. The coated sample microstructure confirms the cermet formation. The macrostructure and SEM with EDS studies align with the microstructure results and exposed defects in as-built sample. The Tafel plot in potentiodynamic polarisation study revealed less corrosion rate, higher corrosion potential and lesser corrosion current density in coated sample than as-built and heat treated samples. Nyquist and Bode plots revealed that heat treatment improved corrosion resistance, while coating offered the highest protection by effectively blocking electrochemical activity.

Steel structures in marine splash zones (MSZ) experience severe corrosion owing to high humidity and frequent wet-dry cycles, which poses considerable threats to structural integrity and operational safety. To achieve intelligent, real-time corrosion monitoring, this study presents a corrosion-rate model based on the Weibull distribution, intended to serve as the core algorithm of smart corrosion sensors that continuously provide corrosion depth data via techniques such as electrochemical impedance spectroscopy or fiber optic sensing. The model was validated through systematic laboratory salt-spray cyclic tests that simulated MSZ conditions; corrosion behaviour was analysed by means of mass-loss measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results reveal a three-stage corrosion progression and confirm that the Weibull model accurately captures the time-variant corrosion behaviour under different splash intensities. The model thus provides a reliable algorithmic foundation for intelligent corrosion monitoring, enabling real-time assessment of structural safety and prediction of residual life.

Abstract This study examines the effects of fiber content, distribution, and interfacial bonding on the thermal, mechanical, and tribological properties of copper matrix composites reinforced with short carbon fibers (C f ), produced via rapid sintering. Uniform composite feedstocks were prepared by mixing gas-atomized pure copper powder with 40 and 60 vol.% copper-coated short carbon fibers using a 3D mixer. The resulting blends were consolidated through the field-assisted sintering technique at temperatures between 900 and 940 °C. Microscopic analysis confirmed a random distribution of the fibers within the matrix and compatible interfacial bonding with the copper. Thermal tests with a dilatometer showed that increasing C f content significantly reduced thermal conductivity and the coefficient of thermal expansion. Tribological tests under low (6 N) and high (20 N) loads demonstrated significantly lower friction coefficients, the lowest 0.2, for the composites compared to pure copper. However, wear rates increased at 20 N under ball-on-disk conditions. This was in contrast to pure copper. The reduced tensile strength of the composites relative to pure copper was attributed to the diminished load-bearing capacity of the short fibers. Pure copper showed shallow localized corrosion pits. In contrast, composites—especially with 60 vol.% C f exhibited— corrosion initiating at the fiber–matrix interface. The lowest corrosion rate was observed at 25 °C.

Metallosurfactant-based surface modification of biomedical alloys for inhibiting BSA adsorption and microbial corrosion.

Ionically bonded interfaces are crucial for achieving selective and stable direct seawater electrolysis, yet their vulnerability under corrosive and high-current conditions limits long-term performance. Here, we report a two-dimensional Fe-MOF@PW8O26.B2O3 heterostructured electrocatalyst, synthesized via a solid-liquid interfacial growth strategy, that integrates robust Fe-O-W and tunable Fe-P-W ionic bonds to strengthen interfacial electronic coupling, redox flexibility, and structural integrity. Subsurface B2O3 enhances surface hydroxylation via Lewis acid-base interactions, facilitating catalyst assembly and OH- affinity, while phosphate polyanions at the interface act as electrostatic shields that repel Cl- ions and modulate the redox environment of Fe active sites. This interfacial configuration enables chlorine-suppressive oxygen evolution with a Faradaic efficiency of 97.93%, achieving a current density of 1.75 A cm-2 at 2.0 V and stable operation above 1.5 A cm-2 for over 500 h in alkaline seawater, with an exceptionally low corrosion rate of 0.016 μm per year. NEXAFS and XPS analyses confirm the presence of dual ionic linkages, while DFT calculations reveal their cooperative role in stabilizing the electronic structure and interfacial charge distribution. Beyond hydrogen production, the spent electrolyte is repurposed for CO2 mineralization, achieving 88.76% conversion to stable carbonates, with cytotoxicity assays confirming reduced environmental toxicity. Together, this study establishes a multifunctional ionically engineered platform for durable, chlorine-free seawater electrolysis and integrated carbon capture, advancing the prospects of circular hydrogen systems.

Purpose This research introduces a comprehensive framework for optimising fibre laser butt welding of NiTi shape memory alloy (SMA) wires, integrating experimental studies, predictive modelling and sustainability evaluation, with particular focus on the tensile strength–corrosion trade-off. Design/methodology/approach A 43-run central composite design (CCD) experiment was conducted to assess how laser power, pulse duration, frequency, wire diameter and filler powder types (Fe/Cu/Ni) influence tensile strength and corrosion rate. The resulting response patterns were examined using ANOVA and Pareto charts, and three modelling methods – adaptive neuro-fuzzy inference system (ANFIS), particle swarm optimised ANFIS (PSO-ANFIS) and Gaussian process regression (GPR) – were compared. A hybrid AHP–entropy approach was used to benchmark the sustainability of different welding techniques. Findings ANOVA and Pareto analysis confirmed pulse time, frequency and power as dominant factors for both responses. Fe filler produced tensile strengths over 400 MPa, while Ni filler had the lowest corrosion rate (∼0.001298 mm/year) and more uniform weld microstructures, showing a strength–corrosion trade-off. GPR model outperformed others with high accuracy for tensile strength (R2 = 0.8752; RMSE = 23.9706 MPa) and corrosion rate (R2 = 0.9565; RMSE = 0.0001 mm/year). Confirmatory tests supported predictions, and fibre laser welding was ranked most sustainable. Practical implications The integration of predictive modelling with sustainability evaluation offers a strong tool for optimising technical performance and environmental impact in NiTi SMA welding. This study's insights are vital for industrial engineering, where high-performance materials and sustainable manufacturing improve reliability, cut costs and ensure environmental compliance. Originality/value The proposed methodology offers a novel comparative perspective on modelling strategies, supporting informed decision-making in advanced manufacturing using a relatively small dataset.

Abstract Magnesium (Mg) alloys possess high specific strength and low density but suffer from poor corrosion resistance, which restricts their broader application in marine and biomedical environments. To overcome this limitation, a superhydrophobic epoxy/polytetrafluoroethylene (PTFE) nanocomposite coating was developed on AZ31B Mg alloy using a spin-coating process. This study aims to clarify how coating architecture and uniformity influence corrosion resistance and long-term durability. Electrochemical analyses revealed that the uniformly coated specimens had a significantly lower corrosion current density (1.85 × 10 –6 A cm −2 ) and higher polarization resistance (3.55 × 10 4 Ω·cm 2 ), resulting in a corrosion rate of only 0.022 mm/year, nearly 94% less than that of the bare substrate. Complementary electrochemical impedance spectroscopy (EIS), salt-spray, and outdoor exposure tests confirmed that the bilayer coating effectively suppresses electrochemical degradation and maintains hydrophobicity over time. These findings demonstrate the necessity of developing architecture-optimized superhydrophobic coatings to achieve durable and scalable protection strategies for lightweight Mg alloys.

Compression and corrosion characterization of Al-B4C-TiO2 hybrid composites for marine superstructure applications