The ability to understand, control, and engineer heat flow is central to applications ranging from energy conversion to thermal management. Heat transport is particularly interesting at the micro- and nanoscale, where the conventional description of diffusive heat conduction can break down and where interfacial thermal transport becomes increasingly relevant. Probing nanoscale heat transport requires experimental methods that are non-invasive, compatible with ultrathin samples, and capable of resolving heat dynamics across interfaces between different materials. Optical pump-probe techniques provide a powerful contactless solution, combining high spatial and temporal resolution to accurately map the temporal dynamics and spatial evolution of material temperatures. Here, we first discuss the recently established technique of spatiotemporal thermometry (STT), which is particularly suitable for in-plane thermal transport. We then propose the technique of material-selective time-resolved thermometry, which is particularly suitable for out-of-plane heat transport. Both techniques follow the evolution of the temperature of thin films in time and space. Together, these two time-resolved approaches provide a platform for quantifying heat transport parameters in materials down to atomic thicknesses, with great potential for exploring nanoscale thermal phenomena.
Laser-induced periodic surface structures (LIPSS) have been employed extensively across many fields of materials surface engineering. LIPSS have previously been demonstrated on carbon fibre materials in literature, yet the impact these treatments have on the mechanical properties of the fibres and their resulting composite materials has remained unreported. Herein, carbon fibres were exposed to ultrashort-pulsed laser irradiation to generate both low spatial frequency and high spatial frequency LIPSS. The resulting surface features were characterised by scanning electron microscopy and evaluated mechanically at both the single-fibre and laminate scales. Laser treatment produced distinct structural colouration and darkening effects that were retained after incorporation into an epoxy matrix. Single-fibre tensile strength decreased by 30.3%–52.5%, while tensile modulus was largely retained. Despite this, composite laminates exhibited no significant loss in flexural strength and only a 10.3% reduction in flexural modulus.
The rapid expansion of portable and wearable electronics has created a simultaneous demand for materials that can both store energy efficiently and protect devices from electromagnetic interference (EMI). In this context, MXenes have emerged as promising candidates due to their high electrical conductivity and rapid ion transport capability. However, their pronounced restacking tendency significantly restricts accessible surface area and limits overall performance. To address this challenge while introducing multifunctionality, redox-active polydiaminoanthraquinone (PDAAQ) was rationally intercalated into Ti _3 C _2 T _X MXene by in situ oxidative polymerization to suppress restacking and accelerate ion transport. Beyond acting as a physical spacer, PDAAQ provides additional pseudocapacitive contribution through quinone-based redox reactions, enhancing the overall charge storage behavior. This present study employs free-standing film architecture, which facilitates continuous electron pathways and improves ion transport without the need for binders or conductive additives. The MXene/PDAAQ free-standing nanocomposite films demonstrated a high specific capacitance of 942.5 F g ^−1 and excellent cycling stability with 96% retention after 5000 cycles. A solid-state asymmetric supercapacitor was assembled using a PVA/H _2 SO _4 gel electrolyte as both the electrolyte and separator. The device exhibited high volumetric and gravimetric capacitances of 423.177 F cm ^−3 (406 F g ^−1 ), respectively, and delivered a volumetric energy density of 30.1 Wh l ^−1 at a power density of 800 W l ^−1 . Beyond energy storage, the same dense and well-oriented conductive network provided effective EMI attenuation. The MXene/PDAAQ nanocomposite film had a high electrical conductivity (12.4 × 10 ^3 S cm ^−1 ) and achieved 40 dB of shielding effectiveness at 11.2 GHz in the X-band, where reflection of electromagnetic waves by the film was identified as the dominant shielding mechanism. The MXene/PDAAQ system shows promising electrochemical performance as well as effective electromagnetic shielding behavior. Each property was examined individually, indicating its potential for use in next-generation electronic devices.
The urgent need to decarbonize medium- to high-temperature industrial process heat, combined with the high cost and limited lifespan of current parabolic trough collectors (PTCs), motivates the development of a simpler, more durable, and lower-cost alternative that retains commercial-grade performance. This work introduces a coating-free, vacuum-free spectrally selective solar absorber achieved by nanotexturing AISI 316 stainless steel with periodic submicron pyramidal arrays. Optical constants were rigorously obtained via multi-objective fitting of a Lorentz–Drude model to experimental data, enabling accurate 3D finite-difference time-domain (FDTD) wave-optics simulations over a broad wavelength range. The pyramidal geometry was optimized using particle swarm optimization coupled with FDTD and a one-dimensional steady-state thermal model. The optimized nanotextured surface (pyramid base 166 nm, height 755 nm) delivers solar absorptance α _s 0.98 and thermal emittance ϵ _th 0.36 (at 400 °C), absorbing 3%–4% more incident solar energy than leading commercial cermet coatings ( α _s 0.95–0.96, ${{\varepsilon}}$ _th = 0.09–0.11) and compensating for the significantly larger emittance in infrared. Under realistic PTC operating conditions ( C = 82 suns, 1000 W m ^−2 incident flux, heat transfer fluid temperature of 250 °C), the monolithic nanotextured receiver achieves a thermal conversion efficiency of 78.6%, fully competitive with the best commercial vacuum-tube receivers (78.5%–79.4%), while eliminating all components prone to degradation. By replacing complex coatings with purely geometric light trapping on a single structural alloy, this design would promisingly offer intrinsic high-temperature stability (>500 °C), immunity to hydrogen-induced or oxidative degradation, and compatibility with scalable nanofabrication, paving the way for significantly simpler, lower-cost, and longer-lifetime parabolic trough systems for both power generation and solar industrial process heat.
To address the significant productivity challenges associated with the qualification and certification (Q&C) tasks of additively manufactured (AM) parts, which have traditionally relied on rigorous post‐build inspection and testing, we propose an integrated framework that combines model‐based qualification and certification (MBQ&C) with autonomous additive manufacturing (AAM). MBQ&C employs high‐fidelity predictive models, developed within the Integrated Computational Materials Engineering (ICME) paradigm, to simulate process–structure–property–performance relationships for assessing a part’s fitness for use. Since predictive models are commonly machine learning (ML)-based or reduced-order surrogates of validated physics models, they run efficiently, enabling timely inference. In parallel, the self-driving AAM utilises ML-based adaptive, closed‐loop control strategies to avoid, mitigate, or repair defects and anomalies during fabrication, thereby increasing the likelihood of producing acceptable parts. A key feature of the combined AAM-MBQ&C framework is that predictive models explicitly incorporate defects or anomalies that persist after the build, using instance-specific data captured via in-situ sensing. This customisation enables a build‐specific assessment of fitness for use, rather than relying on nominal or generic parameters. Such individualised evaluation provides a robust basis for Q&C-related acceptance decisions relating to each build. Additionally, the rapid solution capabilities of ML or reduced-order models enable the determination of a part’s suitability for service shortly after build completion. As the framework matures, it has the potential to substantially reduce reliance on conventional point‐design approaches—such as time‐consuming post‐build computed tomography scanning and costly destructive testing. Thus, the AAM-MBQ&C framework represents a transformative, scalable strategy for quality assurance of AM components, as parts produced within a stable, validated, and certified envelope can be certified with reduced testing. Key benefits include: (1) significant gains in Q&C productivity through efficient, model-centric assessment; (2) performance-based classification of defects into critical and non-critical categories; (3) the ability to predict potential deviations in the performance of parts affected by real-time, adaptive process control interventions relative to those produced under a certified process, and (4) the enabling of virtual Q&C for service environments that are difficult, hazardous, or impractical to access or reproduce experimentally. Collectively, these capabilities strengthen the business case for AM, particularly for high‐consequence and mission‐critical applications. Finally, although this work focuses on powder-based AM, the proposed techniques could be extended to AM processes employing alternative feedstock forms.
Abstract Photoactive-ferroelectric nanostructured composites often exhibit superior performance compared to their individual components, and the interfacial band profile has been regarded as the major contributor to the reported enhancements. In this context, band alignment could serve as a guiding parameter for the screening of novel architectures; therefore, reliable theoretical approaches are desirable to facilitate this formidable task. A practical framework for band-alignment calculations within density functional theory is that developed by Van de Walle et al. , which combines superlattice calculations performed in the generalised gradient approximation (GGA) with independent bulk calculations using the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE). Here, we evaluate the applicability of this 'GGA-HSE’ method for band alignments in complex oxide heterojunctions, using the α -Fe 2 O 3 /BaTiO 3 interface as a representative and technologically relevant case. First, we apply this method to calculate the valence- and conduction-band offsets of model ferroelectric- and halide-based interfaces, establishing a reference line against full HSE band-alignment calculations. Our results demonstrate that the GGA-HSE method yields band offsets consistent with HSE values and is therefore not limited to prototypical oxides. With this validation in place, we then apply the method to the α -Fe 2 O 3 /BaTiO 3 interface. We find that this system exhibits a straddling type-I profile, in which the charge carriers are confined within the photoactive component of the heterostructure. To rationalise the observed enhancement in photocatalytic performance of α -Fe 2 O 3 /BaTiO 3 nanocomposites, we propose a band-structure-related mechanism involving thermally assisted charge transfer and ferroelectric polarisation effects.
Water and ice accumulation on engineering surfaces present significant challenges in numerous applications by increasing weight, altering aerodynamic and hydrodynamic performance, inducing vibrations, and reducing operational reliability. Passive low-ice-adhesion surfaces therefore represent a promising strategy for reducing the energy and mechanical load needed for ice removal. One possible approach is to introduce controlled surface features that promote stress concentration at the ice–solid interface and facilitate ice detachment. However, if such features are too densely distributed or too large, they may also increase mechanical interlocking with ice. Therefore, this study investigates how the size and pitch of laser-induced square features affect the ice adhesion strength of hydrophobized aluminum surfaces. Square features were fabricated on 1050 A aluminum alloy by nanosecond laser texturing and subsequently functionalized with a thin PDMS coating. The side length of the square spots was varied between 150 and 300 μ m, while the center-to-center pitch was systematically varied from 0.5 to 4.0 mm. The surfaces were characterized using scanning electron microscopy, optical profilometry, and apparent static contact angle measurements, while ice adhesion strength was evaluated by horizontal shear detachment of a 20 × 20 × 20 mm ^3 ice cube at −20 °C. The results showed that spot pitch is the key geometrical parameter governing ice adhesion. At the smallest pitch of 0.5 mm, all textured surfaces exhibited higher ice adhesion than the bare reference surface, indicating that densely arranged features promoted mechanical interlocking rather than crack-assisted debonding. With increasing pitch, ice adhesion decreased and reached a minimum at intermediate pitch values, reducing adhesion by up to 65% relative to the PDMS-coated reference surface. These findings show that laser-induced surface geometry must be carefully optimized, since the same type of surface feature can either reduce or increase ice adhesion depending on its size and spacing.
Abstract Van der Waals layered magnetic materials have recently received significant attention for their ability to exhibit antiferromagnetic or ferromagnetic (FM) properties, even at the few-layer or monolayer scale. Among them, Fe 3 GeTe 2 is one of the most extensively studied systems, crystallizing in a hexagonal structure as an itinerant FM with a Curie temperature ( T C ) of ∼220 K in bulk form and strong magnetic anisotropy. In this study, temperature and magnetic field dependence of the four-probe resistance ( R x x ) , thermopower (TEP) ( S ), and Hall resistance ( R x y ) were investigated in thick Fe 3 GeTe 2 flakes with different thicknesses to understand electron and spin transport, as well as spin and magnetic states. R x x decreased with decreasing temperature, confirming metallic behavior, consistent with the observed reduction in the magnitude of the negative TEP. Negative magnetoresistance (MR) with the magnetic field normal to the sample plane exhibited a quadratic field dependence below T C . An anomalous Hall effect was observed below T C , where R x y ( B ) showed a linear field dependence at low fields and saturation at higher fields. The anomalous Hall resistance ( R x y A ) followed a dependence of α R x x + β R x x 2 . A positive in-plane MR was observed when the current was perpendicular to the magnetic field, attributed to increased scattering from the enhanced Lorentz force and related orbital effects. Additionally, a hysteresis behavior was observed when cycling the in-plane magnetic field, likely due to the delay in domain alignment in response to the changing field.
Abstract Materials science underpins national economies and infrastructures worldwide, contributing significantly to the delivery of key services, as well as supporting multiple industrial sectors, including space. The space sector, represents a cornerstone of technological progress, driving both direct and indirect innovation across many terrestrial fields. Taken together, materials science and the space sector represent a transformative frontier that remains only partially exploited, offering opportunities for scientific, economic, and societal advancement. In this context, this roadmap presents a special focus on where such interplay can yield fruitful outcomes over the next two decades, exploring specific intersections between these fields. The rationale behind this is routed in the current demand and forward view for specialized materials to address both terrestrial challenges and extraterrestrial ambitions, with the global space economy projected to reach $1.8 trillion by 2035, requiring a coordinated interdisciplinary effort. Microgravity provides a unique platform to achieve this, enabling critical insights, more precise control over material formation and the creation of advanced materials with enhanced properties for diverse applications. These breakthroughs are already informing applications across a range of industries on Earth, from semiconductors to pharmaceuticals, while laying the groundwork for advanced manufacturing in space. Emerging sectors such as the ‘In-Orbit Economy’ and in-situ resource utilization (ISRU) further underscore this critical opportunity, emphasizing the need for resilient materials that can withstand the harsh conditions of space and utilize extraterrestrial resources sustainably. This roadmap brings together a diverse array of contributions covering relevant subjects across these areas—from space exploration and ISRU to the production of new inorganic, organic, and even ‘living’ materials on microgravity platforms—while paying special attention to concrete examples, i.e. cases with a technological readiness level of 4 or higher, which warrant continued attention and effort.
Abstract Atomic substitution provides a controlled route to engineer lattice dynamics in low-symmetry two-dimensional materials. Here, by combining polarization-resolved Raman spectroscopy and first-principles calculations, we investigate the evolution of phonon characteristics in CrSBr 1 − x Cl x ( 0 ⩽ x ⩽ ∼ 0.5 ) upon partial substitution of Br with Cl atoms. Progressive Cl substitution of Br induces systematic shifts of parent CrSBr out-of-plane A g phonon modes and activates additional Raman features. These features persist across different polarization configurations and excitation energies, reflecting substitution-induced symmetry lowering and local lattice perturbations. Explicit supercell phonon calculations combined with Raman Γ -density-of-states simulations identify these features as symmetry-lowered descendants of parent modes arising from alloy disorder. Complementary strain-dependent calculations reveal that anisotropic lattice compression plays a key role in renormalizing Cr–S dominated phonons. Under near-resonant excitation, stimulated Raman scattering-like amplification remains observable with increasing Cl content, highlighting the resilience of anisotropic electron–phonon coupling in this system.
Artificial intelligence (AI) is accelerating materials prediction and design by enabling efficient exploration of chemical and structural spaces, with particular promise for novel materials discovery. However, novelty in materials discovery encompasses chemical plausibility, structural distinctiveness, property relevance and experimental realisability, making AI-driven novelty claims difficult to substantiate. We introduce a materials property hierarchy, from intrinsic, composition-determined properties to extrinsic, processing-dependent performance, to clarify deployment constraints and distinguish structural, physical and deployment novelty. This framework motivates an evidence-based view of multimodal materials data spanning chemical composition, microstructure, processing, and testing and characterisation, showing that current evidence remains concentrated in composition and idealised structure while heterogeneous, under-represented and weakly integrated modalities limit support for physical and deployment novelty. It also highlights the limitations of benchmarks based mainly on computational labels and proxy novelty criteria. Community-wide standards for data collection, modality alignment and evidence synthesis are needed to support multimodal data construction, process-aware multimodal modelling, feasibility-first generative modelling and deployment-aware benchmarking, so that generative and multimodal AI can design experimentally realisable materials with defensible scientific and practical novelty.
Flexible material platforms are attracting rapidly growing interest in photonics, enabling mechanically compliant optical components for wearable, conformable, and stretchable devices. In this context, transferring high-index semiconductor nanoresonators from bulk substrates to elastomeric supports is both technologically relevant and still challenging. Here we demonstrate and assess the transfer of dewetted Si _1− _x Ge _x and Ge nano-islands acting as a Mie-resonator platform from rigid substrates to polydimethylsiloxane (PDMS). The process combines selective wet-chemical removal of a sacrificial SiO _2 layer, embedding of the nano-islands within PDMS, and final release from the host wafer. Scanning electron microscopy is employed to quantify transfer efficiency and to verify the morphological integrity of the embedded nanostructures. Raman spectroscopy is used to confirm that the crystalline quality and vibrational fingerprints are preserved after transfer, while also providing insight into strain evolution. These results establish a viable route to integrate dewetted group-IV Mie nanoresonators into soft polymer matrices, supporting the development of flexible photonic technologies.
Room-temperature multiferroics such as Aurivillius-phase Bi _6 Ti _2.8 Fe _1.52 Mn _0.68 O _18 (B6TFMO, m = 5) combine ferroelectricity and ferrimagnetism, making them promising for next-generation memory and spintronic devices that exploit domain walls and magnetoelectric coupling. Naturally occurring defects, including out-of-phase boundaries (OPBs), stacking faults, and ‘anatase’-type intergrowths, profoundly influence local strain, electrostatics, and magnetic cation ordering, enabling charged domain walls, polar vortices, and enhanced magnetic interactions. However, their uncontrolled distribution undermines reproducibility across films. Here, we introduce vicinal sapphire substrates (0.2° to 10° miscut) as a powerful handle for engineering these defects during direct liquid injection chemical vapour deposition growth. Systematic increases in step density drive proliferation of OPB defects and stacking faults, along with grain refinement and x-ray diffraction peak broadening/asymmetry, while also triggering tilted (∼10°) b -axis polarisation vectors that enhance vertical polarisation accessibility. Atomic-resolution scanning transmission electron microscopy reveals OPB defects serving as heterogeneous nucleation sites for 180° nominally charged domain walls and polarisation patterns consistent with polar vortices (stabilised 3–5 nm apart). Nanorod precipitates within ‘anatase’-type interlayers stabilise novel anti-hedgehog polarisation configurations reminiscent of skyrmion-like topologies in Aurivillius phases. Critically, PFM uncovers a three-fold reduction in out-of-plane switching voltage (±5 V) for high-miscut films, enabled by selective c -axis response: ∼10° tilted grains rotate the in-plane b -axis polarisation vertical, while defect networks pin lateral domains and channel domain wall motion driven by local strain/electrostatic energy gradients. These findings establish substrate vicinality as a reproducible strategy to sculpt defect landscapes and directionally tune ferroelectric switching in Aurivillius multiferroics, paving the way for sustainable, low-voltage, scalable nanoelectronics with designer polar topologies.
Abstract The anomalous Nernst effect (ANE) in Co x Pd 1 − x alloy thin films has been investigated for the first time over a range of cobalt concentrations ( x = 0.19 − 0.55 ) in samples prepared by electrodeposition. The films were characterized from both the magnetic and thermoelectric point of view, by means of alternating gradient force magnetometry and studying the Nernst and Seebeck effects, in order to assess their suitability for transverse thermoelectric energy conversion. In the adopted experimental setup, maximization of the ANE signal requires a preferential magnetization direction perpendicular to the film plane. It is known that, for this alloy, at co concentrations x ≲ 0.4 the perpendicular magnetic anisotropy overcomes the shape anisotropy; such behavior was verified in the present work through magnetization curves, and correlated with the variations observed in the Nernst signal. The anomalous Nernst coefficient s ANE was found to increase with co concentration, reaching a maximum value of 0.43 μ V K − 1 for the highest measured cobalt content. The obtained values are comparable with those reported for analogous alloys such as Co x Pt 1 − x . We have also measured the transverse thermoelectric voltage at zero applied magnetic field s 0 , since this would eventually be the figure of interest in practical energy harvesting applications. We have obtained a maximum value of s 0 = 0.11 μ V K − 1 at x = 0.37 , highlighting the fact that the coefficient s 0 is affected not only by the intrinsic ANE value, but also by extrinsic factors.
Chromatin is a hierarchically organized soft material whose nanoscale structure and heterogeneity regulate essential genomic functions. Resolving this organization requires molecular imaging materials that combine selective DNA binding with photophysical properties compatible with nanoscale localization and energy transfer under biologically relevant conditions. Conventional bisbenzimide (Hoechst) DNA stains provide robust targeting of nuclear DNA but limited applicability for super-resolution imaging. Here, we investigate the modular molecular engineering strategy in which cyanine chromophores (Cyanine3, Cyanine5, or Cyanine7) are covalently integrated with a bisbenzimide DNA-binding motif through an aliphatic spacer to form hybrid fluorescent materials. This design decouples DNA recognition from optical functionality, allowing independent optimization of binding affinity and photophysical performance. In the resulting conjugates, the cyanine units retain their intrinsic brightness and spectral properties, while the bisbenzimide ligand preserves high-affinity minor-groove binding to nuclear DNA. The Cyanine3-Hoechst and Cyanine5-Hoechst hybrids enable high-contrast imaging of nuclear DNA in fixed and permeabilized cells using long-wavelength excitation (>500 nm), with strongly suppressed extranuclear background. The substantial spectral overlap between Cyanine3 emission and Cyanine5 absorption further enables efficient Förster resonance energy transfer within the nuclear environment, providing a route to probe nanoscale proximity and organization in chromatin. Owing to their favorable photophysical stability and brightness, these hybrid materials also support single-molecule localization microscopy, revealing nanostructured features within the nucleus that are not resolved in diffraction-limited images. This approach provides a versatile platform for developing next-generation imaging materials tailored to the study of chromatin as a dynamic soft matter system.
The anomalous Nernst effect (ANE) in Co $ _x$ Pd $ _{1-x}$ alloy thin films has been investigated for the first time over a range of cobalt concentrations ( $x$ = $0.19-0.55$ ) in samples prepared by electrodeposition. The films were characterized from both the magnetic and thermoelectric point of view, by means of alternating gradient force magnetometry and studying the Nernst and Seebeck effects, in order to assess their suitability for transverse thermoelectric energy conversion. In the adopted experimental setup, maximization of the ANE signal requires a preferential magnetization direction perpendicular to the film plane. It is known that, for this alloy, at co concentrations $ x\lesssim$ 0.4 the perpendicular magnetic anisotropy overcomes the shape anisotropy; such behavior was verified in the present work through magnetization curves, and correlated with the variations observed in the Nernst signal. The anomalous Nernst coefficient $s_\mathrm{ANE}$ was found to increase with co concentration, reaching a maximum value of $0.43 \,\,\mu$ V K $ ^{-1}$ for the highest measured cobalt content. The obtained values are comparable with those reported for analogous alloys such as Co $ _x$ Pt $ _{1-x}$ . We have also measured the transverse thermoelectric voltage at zero applied magnetic field $s_0$ , since this would eventually be the figure of interest in practical energy harvesting applications. We have obtained a maximum value of $s_0 = 0.11 \,\,\mu$ V K $ ^{-1}$ at $x = 0.37$ , highlighting the fact that the coefficient $s_0$ is affected not only by the intrinsic ANE value, but also by extrinsic factors.
The rapid growth of the global population, industrialization, and climate change have intensified the challenges surrounding water resource security. Despite considerable progress in this area, there remains a gap in the literature regarding a comprehensive understanding of the synthesis, modification, and application of Fe 3 O 4 metal–organic frameworks (MOFs) and their derivatives in wastewater treatment. This paper addresses this gap by providing a thorough review of Fe 3 O 4 -based MOFs and their derivatives, focusing on various synthesis techniques such as solvothermal methods, as-grown methods, co-precipitation methods, and layer-by-layer self-assembly. Additionally, a series of surface functionalization strategies including metal ion doping, composite with carbon materials, metal oxide/sulfide composite, non-metallic composite, biopolymer composite, and layered double hydroxide have been explored to enhance the material properties and performance of these frameworks. The applications of Fe 3 O 4 MOFs and their derivatives in removing pollutants such as antibiotics, pesticides, heavy metals and organic dyes from wastewater are also summarized, and future challenges and future developments are predicted. By presenting a detailed examination of these materials and their diverse applications, this paper not only fills a critical gap in the literature but also lays the groundwork for future research into their potential as advanced wastewater treatment agents, offering new pathways for more efficient, sustainable water purification technologies.
In this work, we report on the study on organic-metal hybrid systems, in particular Co–C 60 fullerene thin films. This study mainly focused on the investigation of the morphological and structural evolution of the film surface after various external stimuli designed to provide energy to the system. For film growth, we adopted an innovative approach, combining ion beam sputtering of a pure metal target with thermal evaporation of C 60 in a co deposition setup. The films underwent a series of treatments to induce modifications. Laser and ion irradiations were performed using a pulsed laser, a continuous Ar beam, and a pulsed C beam. In addition, thermal annealing in vacuum was performed to examine the long-term effects of temperature. The composition of deposited film was investigated using ion beam analysis, the morphology and the structure, and the effects of treatments on the films were studied using scanning electron microscope and transmission electron microscopies and Raman spectroscopy. Changes in electrical resistance were also measured to explore potential applications of these films after treatment.
This study investigates the corrosion protection of aluminium heat exchangers used in freezers with a zirconium conversion coating (ZrCC). Tube and fins sections were subjected to a three-step surface treatment comprising (i) alkaline cleaning, (ii) acid desmutting, both with commercial SurTec (R) products, and (iii) deposition of conversion of Zr coating in a hexafluorozirconic acid (H2ZrF6) bath. The resulting surfaces were characterised for morphology, composition, and corrosion behaviour using scanning electron microscopy with energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, potentiodynamic polarisation, and neutral salt spray (NSS) testing. Zr formed a similar to 70 nm oxide-hydroxide layer that preferentially nucleated and grew on cathodic Fe-containing intermetallic particles in tubes and fins. The coating improved passivity and delayed pit initiation in chloride-containing environments by broadening the passivity span Delta E up to 500 mV. Accelerated corrosion testing in NSS (ASTM B117) demonstrates that ZrCC can provide efficient protection for up to 90 h on tube-and-fin substrates, thereby supporting their implementation in industrial heat-exchanger production.
