npj Materials Degradation最新文献

We present a multimodal methodology integrating time-resolved inductively coupled plasma mass spectrometry (ICP-MS) with operando reflected microscopy to characterise electrochemical surface processes. Enabled by a custom scanning flow cell, this approach allows simultaneous high-resolution optical inspection under controlled polarisation and continuous electrolyte flow. While ICP-MS and reflected microscopy have each advanced the study of electrocatalysis and corrosion, their direct combination correlates spatially resolved optical changes with quantitative, time-dependent dissolution kinetics. To illustrate its potential, we examined copper electrodes in dilute NaCl solutions with and without 2-mercaptobenzothiazole (2-MBT), a well-established corrosion inhibitor. The joint analysis distinguished mechanistic regimes of cathodic and oxide dissolution, uniform corrosion, passivation, and localised breakdown by linking morphology and optical features with dissolution profiles. Beyond this case, the methodology provides a versatile platform for operando electrochemical interface characterisation, bridging dynamic surface phenomena with kinetic reactivity.

The analysis of thermal desorption spectra (TDS) and the calculation of hydrogen detrapping activation energies rely on Gaussian peak deconvolution and Choo-Lee plot regression since 1982. However, this method imposes important assumptions about the number and shape of the TDS peaks used for fitting. In this study, we propose the fingerprint method, an alternative approach that eliminates these long-standing constraints. By applying the fingerprint analysis to eight TDS spectra from three different Fe-C model alloys, we demonstrate its exceptional sensitivity and ability to resolve activation energy distributions - the material fingerprint - unattainable with traditional methods. We further showcase by manual and automated analysis how the such obtained fingerprints can be used to uniquely distinguish the TDS spectra of each alloy independent of the heating rate. Thus the fingerprint method also increases experimental efficiency by reducing the amount of necessary heating rates for TDS down to one.

This study examines hydrogen permeation and trapping in three types of natural gas pipeline steels from different decades in Canada-modern, vintage, and legacy steels. Electrochemical permeation experiments were conducted to measure the diffusion coefficient, subsurface concentration, and trap density of hydrogen. The results were analyzed to evaluate the susceptibility of these steels to hydrogen embrittlement and to understand the effects of hydrogen on their mechanical properties. Vintage steel exhibited 50% higher steady-state permeation current and 97% greater effective diffusivity compared to modern steel, while legacy steel showed intermediate values. Hydrogen diffusion increased with grain size and pearlite content but decreased with dislocation density. Modern steel demonstrated the highest resistance to hydrogen permeation due to its finer grain structure and higher dislocation density. This study provides essential insights into the diffusion behavior and trapping mechanisms of hydrogen in natural gas pipeline steels, enhancing the understanding of material performance under hydrogen exposure.

A phase-field model is developed to simulate intergranular corrosion of ferritic/martensitic steels exposed to liquid lithium. The chromium concentration of the material is used to track the mass transport within the metal and liquid (corrosive) phase. The framework naturally captures intergranular corrosion by enhancing the diffusion of chromium along grain boundaries relative to the grain bulk with no special treatment for the corrosion front evolution. The formulation applies to arbitrary 2D and 3D polycrystalline geometries. The framework reproduces experimental measurements of weight loss and corrosion depth for a 9 wt% Cr ferritic/martensitic steel exposed to static lithium at 600 °C. A sensitivity analysis, varying near-surface grain density, grain size, and chromium depletion thickness, highlights the microstructural influence in the corrosion process. Moreover, the significance of saturation is considered and evaluated. Simulation results show that near-surface grain density is a deciding factor, whereas grain size dictates the susceptibility to intergranular corrosion.

At the Ballidon experiment, one of the longest running glass durability studies, modern and simulant archaeological glasses were buried in mildly alkaline, under-saturated, conditions for 52 years. Glass surfaces were analysed to determine the extent and mechanisms of alteration. Alteration layer chemistry was complex and included Ca from the surrounding limestone sediment and P from porewater resulting in Ca, Pb and Fe-phosphate rich phases interspersed with Si and Al rich regions. There was evidence for ongoing evolution of the alteration layer structure due to continued fluid ingress. Lamellae in the silica-rich regions approximately numbering the years of burial and indicating a possible link between their formation and seasonal climate cycling. Comparison of field samples with laboratory dissolution tests highlighted the impact of surface finish on initial alteration rate and the limitations of using alteration layer thickness to estimate the amount of glass that has dissolved.

Understanding biocide performance in mixed-species biofilms is critical to mitigating microbiologically influenced corrosion (MIC). In this study, a novel dual anaerobic biofilm reactor was used to evaluate glutaraldehyde efficacy under environmentally relevant conditions, using a complex microbial consortium from marine sediment. Despite biocide dosing, biofilms persisted and induced localized corrosion, indicating incomplete mitigation. Each biocide application led to an electronegative shift in E _corr and a reduction in $H_{2}S$ concentration, suggesting partial suppression of microbial activity. Raman spectroscopy and profilometry revealed differences in corrosion product composition and pit morphology between biotic and abiotic systems. 16S rRNA sequencing showed enrichment of stress-tolerant genera, including Exiguobacterium and Serpentinicella, consistent with increased chemical tolerance. These findings highlight the limitations of conventional biocide strategies and demonstrate the need for adaptive, community-informed treatment approaches. The dual-reactor model provides a robust platform for future MIC standardization efforts and mechanistic investigation of biofilm resilience under anoxic conditions.

The corrosion of iron or steel in contact with bentonite is a key factor affecting the long-term safety of radioactive waste disposal system. Previous studies focused on corrosion after long-term burial in compact bentonites, however, little work was dedicated to the corrosion of iron exposed to bentonite slurries, that can appear in case of fracture of the bentonite jacket separating steel from underground water. In this study, accelerated corrosion experiments were performed on pure iron in basic bentonite slurries (pH 9-10) using various electrochemical corrosion techniques. The anodic dissolution of iron was larger in more concentrated bentonite slurries and resulted in the formation of an acidic gel. This gel results from a cationic exchange between Fe²⁺ ions released by corrosion and protons from surface or edge locations in bentonite. Its growth appears to be governed by reactions at the gel-bentonite interface rather than diffusion processes.

This work aims to develop multilayer coating systems to enhance the long-term corrosion performance of aluminium-based components. The systems consists of a high-performance ceramic matrix that provides physical barrier protection, and a topcoat layer containing encapsulated Ce-based inhibitors, offering active corrosion protection through controlled released mechanisms. Two types of nanoparticles were used for the encapsulation, zeolite and halloysite nanotubes, each with different release triggers and kinetics. Multifunctional coatings demonstrated a superior corrosion performance compared to the passive unmodified coatings. Inhibitor release from the nanoparticles was triggered by ionic exchange processes and changes in pH associated with corrosion activity.

Understanding the dissolution and passivation of iron in aqueous environments is essential for enhancing its corrosion resistance and expanding its applications. We present Thermo-Kinetic (TK) diagrams for iron in deaerated solutions with no added sodium sulfate (Na₂SO₄) and with 0.1 M Na₂SO₄ over the pH range 1-14, constructed by integrating current density contours from potentiodynamic polarization with thermodynamic E-pH diagrams. TK diagrams indicate that in solutions with no added Na₂SO₄, iron passivates above pH 7, with a minimum passive current density (i_p) of 5 ×10^-6 mA·cm^-2 at pH 8. The addition of 0.1 M Na₂SO₄ delayed passivation until pH 12 and increased i_p nearly tenfold. Galvanostatic (GS) polarization and EIS validated the TK diagram results. XPS after GS polarization revealed an FeOOH/Fe₂O₃ film at pH 10, while Fe₃O₄/Fe₂O₃ dominated at pH 12 and 14. These results clarify how sulfate compromises iron passivity and highlight TK diagrams as a powerful tool for mapping corrosion behavior.

Polydimethylsiloxane (PDMS) is a synthetic elastomer widely used in biomedical and industrial applications. Despite its widespread use, the natural evolution of its mechanical and surface properties over time remains poorly understood. In this study, we fabricated PDMS samples with base-to-curing agent mixing ratios from 5:1 to 30:1 and aged them for up to 8 weeks under six non-harsh conditions at room temperature. Contact angle measurements revealed increasing hydrophobicity with aging, with maximum increases up to 16.5°. Mechanical testing showed up to 130% increases in Young's modulus and 60% changes in flexibility after 5 weeks. Storage in mineral oil best preserved surface hydrophilicity, while storage in water best maintained mechanical integrity. These results provide a framework for optimizing PDMS storage conditions in microfluidic and biomedical device applications.