With the increasing duration of space missions, the impact of fungi on aerospace materials requires systematic investigation. We evaluate the adaptability of Aspergillus brasiliensis and its corrosion effects on aluminum alloy under space conditions through a 90-day experiment. Fungal growth characteristics, ultrastructural changes, metabolic activity, and interactions with the material surface are analyzed. The results show that Aspergillus brasiliensis maintains high adaptability to microgravity, exhibiting thickened cell walls, enhanced spore formation, and increased metabolic activity. Corrosion analysis reveals that fungal attachment accelerates localized material degradation through organic acid secretion and oxygen concentration differentials. The microgravity environment further amplifies these effects by influencing fungal metabolism and altering corrosion dynamics. Compared to ground-based conditions, space-exposed samples show significantly higher organic acid concentrations and metal ion dissolution, indicating intensified corrosion. These findings enhance the understanding of microbial corrosion mechanisms in space and provide a foundation for antifungal strategies to improve the reliability of aerospace materials during long-term missions.

To evaluate the effectiveness of the neutral salt spray (NSS) test in simulating the corrosion behavior of 6061-T6 aluminum alloy in marine atmospheric environments, corrosion kinetics, corrosion product characteristics, and electrochemical behavior were comparatively investigated for samples exposed to NSS for 96 h, 240 h, 480 h, 720 h, and 1008 h, as well as samples subjected to 21 months of outdoor exposure in the coastal atmospheric of Hainan. Based on the comparative analysis, a corrosion prediction model applicable to marine atmospheric conditions was established.The results indicate that the corrosion products of 6061-T6 aluminum alloy in both environments are mainly composed of Al(OH)(3) and Al2O3, and the corrosion kinetics follow a power-law relationship.Based on corrosion weight-loss data, the kinetic models for NSS and marine atmospheric exposure are Delta W = 0.042t(0.635) and Delta W = 1.37t(0.29), respectively, corresponding to an acceleration factor expressed as K = 36.6t(0.538).From the perspective of maximum pit depth evolution, the pit growth models for NSS and marine atmospheric exposure are Y = 1.869t(0.307) and Y = 62.046t(0.222,) respectively, with an acceleration factor of K = 0.0976t(0.277) (K < 1).These results indicate that NSS testing can significantly accelerate the overall corrosion process but cannot effectively accelerate pit depth development, indicating that long-term outdoor corrosion behavior cannot be directly predicted using a constant acceleration factor.Therefore, a nonlinear time-dependent acceleration model is proposed to guide the selection of appropriate acceleration factors for different service times, providing a more reliable basis for evaluating the service life of 6xxx aluminum alloys in marine atmospheric environments using NSS testing.

This study systematically investigated the effects of TiC addition on the microstructure and hydrogen embrittlement (HE) behavior of laser powder bed fusion (LPBF) 15-5 PH stainless steel. The addition of TiC refined the microstructure, transforming lath martensite into fine equiaxed grains and reducing the average grain size from 3.32 μm to 1.25 μm. Meanwhile, the retained austenite content increased by approximately 9.5%, accompanied by a reduction in kernel average misorientation (KAM). Transmission electron microscopy (TEM) analysis further revealed the formation of incoherent TiC/matrix interfaces and nanotwins. After TiC addition, the hydrogen content decreased from 3.12 ppm to 1.97 ppm, and the hydrogen embrittlement sensitivity, evaluated by the loss of elongation, decreased by approximately 75%. Fractography and electron backscatter diffraction (EBSD)-based crack propagation analysis demonstrated that large blocky retained austenite regions effectively deflected and hindered crack propagation. The improved HE resistance was interpreted as being associated with the synergistic effects of reduced local strain concentration, possible hydrogen trapping at incoherent TiC/matrix interfaces, and crack arrest by retained austenite.

Electrochemical migration (ECM) has become a major reliability concern in miniaturized and high-density electronic components, particularly under damp-heat and condensation environments. This study comparatively investigates the ECM behavior of chip resistors exposed to these two moisture regimes. After applying a 6 V bias voltage for 30 min under damp-heat atmospheres with 60 %, 70 %, and 80 % relative humidity, no significant signs of corrosion were observed at the resistor terminals. In damp-heat conditions (up to 90 % RH), the anode underwent gradual Sn oxidation dominated by Sn4+ species, yet no dendritic structures were observed due to the absence of a continuous electrolyte film. In contrast, condensation environments (RH > 60 %) facilitated the formation of a continuous liquid layer, leading to rapid ECM initiation and the growth of Sn-based dendrites enriched in Sn2+ species. Furthermore, as the relative humidity increased, the degree of corrosion at both ends of the resistor became more severe correspondingly. At 90 % RH, simultaneous anodic darkening and aggravated corrosion were observed, confirming the accelerated redox processes within the condensed electrolyte. The results demonstrate that ECM failure occurs only when both a continuous electrolyte film and an external bias potential coexist, providing new insights into moisture-induced reliability degradation of surface-mount components.

This study examines how TiC reinforcement and aging at 480 °C (1–10 h) modulate the pitting corrosion resistance of laser powder bed fusion (LPBF) 15-5 PH stainless steel. TiC addition refined martensitic laths into ∼1 μm equiaxed grains, increased retained austenite to 13%, and raised the critical pitting potential from 0.33 to 0.36 VSCE through grain refinement and austenite stabilization. During aging, austenite content in the TiC reinforced LPBF stainless steel composite increased continuously, reaching maximum at 48.8%, while MnS-type inclusions formed in the LPBF 15-5 PH stainless steel. Prolonged aging triggered a competition between beneficial austenite enrichment and detrimental carbide precipitation, governing the final corrosion performance. The results clarify the synergistic mechanisms by which TiC and post heat treatment tailor microstructure to enhance pitting corrosion resistance.

This study investigates the failure dynamics and dendrite growth characteristics under simulated condensing conditions, employing real-time current monitoring, localized pH testing, and comprehensive characterization. The results reveal that condensation-induced electrochemical migration (ECM) is a continuously evolving dynamic failure process, which can be divided into five distinct stages. It initiates with the heterogeneous nucleation and growth of surface dew droplets, followed by droplet coalescence to form a continuous liquid film. This subsequently triggers pitting and dissolution of the tin-based alloy anode, after which tin ions migrate toward the cathode and deposit continuously. Ultimately, dendrites bridge the electrodes, leading to short-circuiting. The dendrites formed during migration consist of the beta-Sn single phase, and their morphological evolution is governed by the ion concentration gradient. Notably, silver and copper from the alloy do not migrate but remain as detached particles within the interdendritic gaps.

6061 aluminum alloy is lightweight and has good thermal conductivity, while 304 stainless steel possesses excellent mechanical properties and corrosion resistance; both have broad application prospects in cooling circuits. Propylene glycol coolant shows great potential in liquid cooling systems due to its low toxicity and good antifreeze properties. However, during operation, galvanic corrosion may occur when the two metals come into direct contact within the coolant, thereby threatening system safety and service life. This study focuses on 6061 aluminum alloy, 304 stainless steel, and their galvanic couples. Electrochemical testing, SEM, 3D confocal microscopy, and XPS were used to systematically investigate their self-corrosion and galvanic corrosion behavior in propylene glycol coolant at pH values of 4.8, 6.8, and 8.8. The results indicate that 6061 aluminum alloy is more sensitive to pH changes; its corrosion resistance first increases and then decreases as pH rises, with the least corrosion occurring at pH = 6.8 and the most severe at pH = 4.8. 304 stainless steel exhibited lower corrosion rates at pH 6.8 and 8.8, but corrosion significantly worsened at pH 4.8. For the 6061 aluminum alloy/304 stainless steel couple, the galvanic current first decreased and then increased with rising pH, while the galvanic potential first increased and then decreased. The 6061 aluminum alloy consistently acted as the anode, and the 304 stainless steel consistently acted as the cathode, with the highest sensitivity to galvanic corrosion observed at pH 4.8. XPS analysis shows that under different pH conditions, the corrosion products of 6061 aluminum alloy are Al(OH)3 and Al2O3, while the main components of the passivation film on 304 stainless steel remain unchanged.

Cyclic immersion corrosion tests were conducted to simulate the industrial atmospheric corrosion behavior of Q345qENH weathering steel and Q345qD steel. Corrosion kinetics were evaluated via mass-loss measurements, and microstructural evolution and corrosion mechanisms were investigated using metallography, confocal laser scanning microscopy, SEM-EDS, SKPFM, XRD, and electrochemical tests. The results indicate that Q345qENH steel exhibits superior corrosion resistance. Following spheroidization, its inclusions are uniformly distributed with reduced porosity, forming a composite structure of (Al, Mg)Ox enveloped by CaS-CaO/MnS. This homogeneous microstructure promotes uniform corrosion, enabling the development of a protective rust layer. As the test progressed, the rust layer thickened and eventually developed a double-layer structure: Cr enriched in the inner layer, with Cu concentrated in discrete regions. Both steels produced corrosion products consisting of alpha-FeOOH, Fe3O4, gamma-FeOOH, and Fe2O3. Semi-quantitative analysis confirmed that the alpha*/gamma* ratio of Q345qENH increased continuously over time. The corrosion mechanism comprises three stages: (1) Initiation, in which dissolution of CaS/CaO at inclusions lowers the local pH, accelerating the dissolution of Cr, Fe, and Cu and forming Cr-/Cu-rich products; (2) Rapid formation of a wet-dry cyclic rust layer, where Cr and Cu participate in reactions to generate protective alpha-(Fe1-xCrx)OOH, FeCr2O4, CuFeO2, and metallic Cu, inhibiting corrosive medium penetration and repairing defects in the rust layer; (3) Dynamic stabilization, during which continued corrosion leads to further thickening of the rust layer, resulting in a loose outer layer and a dense inner layer that primarily contributes to the protective performance of Q345qENH steel.

The cooling condition after austenitization plays a critical role in determining the corrosion performance of additively manufactured martensitic stainless steel composites. In this work, the effect of cooling rate on the pitting corrosion behavior of WC/W2C reinforced laser powder bed fusion (LPBF) 420 stainless steel composites was systematically investigated using electrochemical measurements, microstructural characterization, and surface analysis techniques. The results reveal a cooling-rate-dependent transition in the dominant pitting initiation mechanism. Under furnace cooling, extensive diffusion of W and C promotes the formation of a continuous W-rich precipitates phase along grain boundaries, which act as preferential pit initiation sites. When the cooling rate increases, grain-boundary precipitation is largely suppressed. Consequently, the pit initiation sites adjacent to WC/W2C particles, where micro-galvanic coupling between the particles and the surrounding matrix drives interfacial pit formation. With further increases in cooling rate (oil and water cooling), the particle-matrix interface remains the primary pit initiation site; however, the stability of the passive film is significantly enhanced. In particular, water cooling produces a WO3 enriched passive film with a higher O2-/OHratio, resulting in improved resistance to chloride-induced breakdown. Consequently, the critical pitting potential increases monotonically with cooling rate, reflecting a mechanistic transition from precipitationcontrolled to passive-film-stabilized galvanic pitting.

Microbiologically influenced corrosion (MIC) poses a potential risk to the long-term reliability of structural materials in space environments, particularly under microgravity conditions where microbial growth and interfacial processes may differ significantly from those on Earth. In this study, the corrosion behavior of an aerospace aluminum alloy induced by Aspergillus brasiliensis was investigated under real space microgravity conditions, with parallel ground-based experiments for comparison. The results show that microgravity significantly enhances fungal activity and alters interfacial transport conditions. Compared with ground conditions, higher concentrations of organic acids, especially oxalic acid, and increased release of Al³⁺, K⁺, and Mg²⁺ ions were observed under space conditions, indicating intensified metal dissolution. Meanwhile, microgravity promotes the formation of thicker and more heterogeneous biofilms, leading to non-uniform interfacial contact and localized chemical environments. As a result, the corrosion morphology under space microgravity is characterized by a reduced number of pits but significantly increased pit depth, demonstrating more severe localized corrosion. This behavior is attributed to the combined effects of enhanced metabolite production and diffusion-dominated mass transport, which facilitate the accumulation of corrosive species at the fungus–metal interface. Overall, the corrosion of aluminum alloy under space microgravity is governed by the coupled effects of microbial activity and interfacial transport processes. These findings provide new insights into corrosion mechanisms in space environments and offer guidance for corrosion risk assessment and material reliability in long-duration aerospace applications.

Through natural exposure tests and corrosion monitoring technology, the differences between surface microenvironment and air environment of ultra-high-strength steel in three environments: outdoor, shutter and indoor air conditioning were compared. Results unveil that the corrosion contribution rate of condensation is 72.1% in the outdoor environment. In a shielded environment, corrosion of the material is less affected by radiative cooling at night, but more affected by ambient temperature, relative humidity, and surface adsorbent. Based on the research results, an atmospheric corrosion model of ultra-high-strength steel in exposed and shaded environments was established.

This study comprehensively investigates the corrosion behavior and underlying mechanisms of zinc and zinc–aluminum alloy coatings under neutral salt spray conditions. A multi-scale analytical approach integrating macroscopic and microscopic morphological characterization, corrosion kinetics analysis, and conventional electrochemical techniques was employed to elucidate the complete corrosion process. The corrosion resistance of both coatings was systematically evaluated, revealing the superior durability of the zinc–aluminum alloy coating, which is attributed to its distinct corrosion-inhibiting mechanisms. Significant differences in phase composition and corrosion product film structure were observed between the two coatings. The zinc coating consists of a single zinc phase, whereas the zinc–aluminum alloy coating contains zinc, aluminum, and Zn–Al intermetallic phases. The predominant corrosion products of the zinc coating are ZnO and Zn5(OH)8Cl2·H2O, while those formed on the zinc–aluminum alloy coating are primarily Al2O3 and ZnAl2(OH)8CO3. In the zinc–aluminum alloy system, the zinc phase preferentially corrodes, providing sacrificial anodic protection, while the formation of a passive aluminum oxide film further enhances corrosion resistance. In addition, the generation of layered double hydroxides (LDHs) contributes to the dynamic self-healing of the corrosion product layer. Compared with conventional zinc coatings, the zinc–aluminum alloy coating exhibits a 2.5- to 3-fold improvement in corrosion resistance.

This study investigated the degradation behavior of a polyurethane acrylate coating/Q345B steel system under the coastal atmospheric conditions of Wenchang, Hainan, and evaluated the correlation between indoor accelerated tests and outdoor exposure. Outdoor exposure tests, single-factor accelerated tests (UV irradiation and neutral salt spray), and a multi-factor cyclic accelerated test combining UV, salt spray, humidity, and thermal cycling were conducted. Coating degradation was characterized by morphological observation, gloss measurement, adhesion testing, and electrochemical impedance spectroscopy. The results showed that after 8 months of outdoor exposure, localized rust spots, blistering, and under-film corrosion appeared on the coating surface. The gloss loss rate reached 15.72% after 3 months, while adhesion decreased from 5.83 MPa to 2.39 MPa during prolonged exposure. UV irradiation mainly affected gloss degradation, whereas corrosive media penetration played a dominant role in adhesion loss and electrochemical deterioration. Compared with single-factor tests, the multi-factor cyclic accelerated test exhibited the highest correlation with outdoor exposure. The corresponding correlation coefficients for gloss loss, adhesion, and low-frequency impedance modulus were 0.9764, 0.9988, and 0.9929, respectively, while the gray relational coefficients reached 0.8334, 0.8467, and 0.7977. These results demonstrate that the multi-factor cyclic accelerated test more accurately reproduces the degradation behavior and failure characteristics observed in the coastal atmosphere of Hainan. The proposed method provides a practical approach for indoor-outdoor correlation analysis and durability evaluation of protective coatings in marine atmospheric environments.

The rapid expansion of the offshore photovoltaic (PV) industry demands structural materials with superior durability to withstand harsh marine environments for a mandatory service life of 27 years. Consequently, establishing a method to accurately predict the longevity of hot-dip zinc-aluminum-magnesium (Zn-Al-Mg) coated steel has become a critical priority. This study establishes an indoor accelerated corrosion test simulating the Hainan tropical marine atmosphere using an enthalpy-based environmental spectrum conversion method. The correlation between the indoor simulation and actual outdoor exposure was rigorously verified through multi-scale characterization and gray relational analysis (GRA). Results demonstrate that the corrosion kinetics in both environments follow a highly consistent power-law growth model. The corrosion products are identically composed of ZnO, Simonkolleite, Al2O3, and MgZn2, which synergistically form a dense barrier inhibiting corrosive ion infiltration. A strong quantitative correlation was achieved (gray relational grade gamma = 0.6038), validating the spectrum's mechanistic fidelity. Based on this validated model, the predicted 27 year corrosion thickness losses are 21.18 mu m (outdoor) and 15.88 mu m (indoor). Despite deviations caused by the absence of mechanical wear in laboratory settings, the consistent kinetic trends prove that the designed spectrum effectively reproduces the failure behavior of ZAM coatings, providing a reliable evaluation framework for offshore PV material selection.

Purpose This study aims to establish a corrosion prediction model for Hainan atmospheric environments by comparing the corrosion behavior of 5083 aluminum alloy in neutral salt spray (NSS) tests and outdoor exposure tests in the Hainan coastal atmosphere.Design/methodology/approach The 5083 aluminum alloy was subjected to various exposure durations in both NSS tests and outdoor tests in Hainan Coastal. After testing, multiple characterization methods - including energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and x-ray diffraction (XRD) - were used to examine the samples, and the indoor and outdoor data obtained were compared and analyzed accordingly.Findings While both environments produce Al(OH)3 and Al2O3, the outdoor Hainan exposure uniquely promotes the formation of the AlO(OH) phase, influenced by the intense wet-dry cyclic effects of the tropical coastal environment. The NSS acceleration factor was found to be time-dependent rather than constant, reflecting the distinct protective evolution of corrosion layers under these specific experimental systems.Originality/value By analyzing the indoor and outdoor experimental data, this study establishes a non-constant rate model describing the correlation between indoor and outdoor corrosion behavior, whose kinetic framework may provide a basis for predicting corrosion trends under the specific conditions investigated.

In this study, low-alloy structural steels with different La and Ce contents were prepared via vacuum smelting and controlled rolling and controlled cooling technologies, and their microstructures were characterized. The influence of La and Ce on the corrosion resistance of low-alloy steels was compared through indoor cyclic-immersion accelerated tests simulating tropical marine atmospheres. The corrosion mechanism of low-alloy steels with different La and Ce contents in simulated tropical marine atmospheres was investigated using electrochemical measurements and corrosion product analysis. The results show that La and Ce improve the uniform corrosion resistance of low-alloy steels. With increasing La/Ce content, the corrosion current density decreased from 1.8936 × 10-6 A cm-2 for 0LaCe to 1.29 × 10-6 A cm-2 for 0.3LaCe, corresponding to a reduction of approximately 31.9%. This is attributed to the fact that La/Ce addition promotes rust layer stabilization and densification, as suggested by the evolution of major rust phases and the presence of La/Ce-related oxidized species. Meanwhile, alloying with La and Ce improves the cracking of the rust layer, reduces the number of pores, and stabilizes the rust layer structure.

The effect of nickel alloying on the surface and interface microstructure and pitting corrosion behavior of laser powder bed fusion (LPBF)-produced 2205 duplex stainless steel (DSS) was studied. Ni addition promoted austenite formation (>20 %), refined grains (from 117 to 181 & micro;m to 28-36 & micro;m), and reduced low-angle grain boundaries (LAGBs) (60-15 %). In addition, the critical pitting temperature (CPT) was increased by 10-20 degrees C in 0.2-1 M NaCl, demonstrating a significant enhancement of pitting resistance. Unlike LPBF 2205 DSS, LPBF 22Cr DSS (nickel over alloyed) exhibited building direction dependent pitting corrosion resistance: in 0.2 M NaCl, the XOY plane showed a lower CPT than XOZ/YOZ, but this ranking was reversed at >0.6 M NaCl. Two pit nucleation sites were identified in LPBF 2205 DSS, as opposed to five in LPBF 22Cr DSS. Pit nucleation susceptibility was driven by austenite content, grain boundary length, and LAGB proportion. The high Cl- sensitivity of Type IV sites on XOZ/YOZ planes in 22Cr DSS resulted in their lower CPT compared to the XOY plane in >0.6 M NaCl.

To investigate the aging failure mechanism of epoxy Zn-Al composite coatings on steel grid supports in industrial marine environments, the corrosion conditions of "high Cl-+ high concentrations of industrial acid gases + alternating wet-dry cycles" in the Caofeidian Port Area of Bohai Bay were taken as the testing background. A salt spray/wet-dry alternating cycle test combined with outdoor exposure testing was adopted. Coating performance and morphological evolution were analyzed via thickness measurements, adhesion tests, electrochemical impedance spectroscopy (EIS), 3D laser confocal microscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Results indicate a three-stage failure progression: Initial protective stage (Cycles 0-3): The coating remains dense and smooth with minimal color change, gradual thickness increase, and high adhesion. EIS results show |Z| at 0.01 Hz is approximately 108-109 S2 center dot cm2, demonstrating a significant physical barrier function. Localized failure stage (4 cycles): Localized rust spots appear on the coating surface, thickness growth accelerates, adhesion decreases abruptly, |Z| at 0.01 Hz drops to 107 S2 center dot cm2, and the penetration of corrosive media triggers Zn dissolution. Expanded failure stage (>= 5 cycles): Corrosion spots expand, the contents of Zn and Al decrease sharply, Fe and O are enriched, |Z| at 0.01 Hz reaches 106 S2 center dot cm2, the coating blisters and peels off, leading to complete failure. This study provides a theoretical basis for optimizing protection strategies in industrial marine environments.

Beryllium bronze, as a critical material for precision spacecraft components, faces microbial corrosion risks during prolonged manned missions. Leveraging the China Space Station (CSS), this study conducted the first in-orbit investigation of beryllium bronze corrosion induced by Aspergillus brasiliensis under true microgravity. The results showed that A. brasiliensis secreted organic acids predominantly composed of oxalic acid under both gravity conditions, enhancing corrosion activity. Microgravity altered the dynamics of liquid films and the deposition characteristics of corrosion products, significantly increasing the thickness and compactness of the corrosion layer. In space, corrosion products exhibited higher oxidation states, with accelerated Cu(I) oxidation and enhanced organic complexation promoting Cu(II) enrichment and the formation of a dense organic-inorganic composite layer. This layer served as a physical barrier, embedding spores that continued metabolic activity, enabling uniform diffusion of corrosive media, thereby shifting the corrosion mode from vertical penetrating pitting on Earth to lateral expansion in space. This study further clarifies the regulatory role of gravity in microbe-metal interfacial interactions and corrosion mechanisms, providing essential scientific evidence for the protective design and in orbit service reliability of spacecraft materials.

The influence of laser remelting on the pitting and wear performance of WC/W2C reinforced 420 stainless steel composites fabricated by laser powder bed fusion (LPBF) was investigated. Laser re-melting enhances the dissolution of WC/W2C and increases the thickness of in-situ reaction layers between reinforcement particles and matrix. Re-melting reduces pit susceptibility near reinforcement particles in LPBF components, however, Epit primarily depends on austenite content, result in the pitting corrosion resistance follows\: LR0 (no laser remelting, 0.47 V-SCE) > LR3 (3 laser remelting cycles, 0.43 V-SCE) > LR2 (2 cycles, 0.39 V-SCE) > LR1 (1 cycle, 0.32 V-SCE). The primary wear mechanism was determined to be tribo-oxidation, accompanied by a secondary abrasion mechanism. This study demonstrates the role of re-melting in optimizing corrosion-wear performance.