Oxidation of Metals最新文献

Corrosion-induced material degradation poses significant challenges in high-stakes industries such as aerospace, oil and gas, and power generation. This review provides a comprehensive analysis of four primary corrosion failure mechanisms - stress corrosion cracking (SCC), hydrogen embrittlement (HE), pitting corrosion, and uniform corrosion - with focus on their initiation, progression, and impact on advanced materials under extreme environmental conditions. Emphasis was given to the critical role of environmental factors such as temperature, humidity, and aggressive chemicals in accelerating corrosion processes. The review also highlights the application of advanced microscopic techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), ultrasonic imaging, and in situ Raman spectroscopy with DFT calculations, which enable detailed insights into microstructural changes and surface degradation associated with corrosion. Furthermore, emerging corrosion-resistant materials, such as high-entropy alloys and self-healing coatings, are discussed alongside innovative technologies such as machine learning, digital twins, and real-time corrosion monitoring which hold promises for enhancing material durability and optimizing maintenance strategies. Despite notable advancements, challenges remain in addressing the combined effects of multiple environmental factors and the long-term behavior of novel materials. Future research must focus on developing integrated, multiscale predictive models, improving real-time monitoring systems, and advancing corrosion-resistant technologies to mitigate material degradation in critical industrial applications.

This paper studies the influence of laser shock peening (LSP) on the high-temperature oxidation behavior of NiPtAl-Hf coatings and evaluates their performance under thermal cycling conditions. The surface morphology and microstructure of the coatings were characterized and analyzed. High-temperature service performance was evaluated by examining the phase transition of θ-Al₂O₃ and α-Al₂O₃ and the evolution of the thermally grown oxide (TGO) through transient oxidation and thermal cycling tests. Results showed that LSP significantly promotes the phase transition from θ-Al₂O₃ to α-Al₂O₃. The effect is attributed to the high-density dislocations and plastic deformation regions introduced by LSP, which provide abundant heterogeneous nucleation sites for α-Al₂O₃. Comparative cyclic oxidation experiments further showed that LSP refines the grain structure and introduces dislocation networks, enhancing aluminum diffusion for selective oxidation and mitigating thermal stress generated during thermal cycling process. Consequently, the TGO exhibits more stable growth with reduced cracking. Additionally, LSP introduces a high density of dislocations, which can act as short-circuit diffusion channels for the rapid diffusion of Al element. The accelerated Al supply promotes the rapid formation of a continuous and dense Al₂O₃ film during the initial stage of oxidation. These findings highlight the potential of LSP as an effective strategy to enhance the thermal cycling performance of NiPtAl-Hf coatings for high-temperature applications.

SiC/SiC ceramic matrix composites (CMCs) are desired for use in combustion environments to achieve higher turbine operating temperatures. However, CMCs require environmental barrier coatings (EBCs) for protection from the gas environment. EBC systems are known to primarily fail through coating delamination via growth of a thermally grown oxide (TGO) at the EBC—silicon bond coating interface when exposed to steam, which accelerates the TGO growth rate. The TGO undergoes a phase transformation during thermal cycling, which results in stresses that may encourage EBC spallation. Yb-silicate EBCs with mullite and yttrium aluminum garnet (YAG) dopant additions were deposited on SiC substrates with a Si intermediate bond coating and exposed to thermal cycling in steam at 1350 °C. The impact of Al dopant additions on the TGO growth rate and the SiO₂ phase transformation was assessed. Photo-stimulated luminescence spectroscopy (PSLS) was used to characterize the Al-containing phases and to measure stress evolution in the EBC following exposure using the stress-induced peak shift of the R-lines of mullite. Raman microscopy was used to map the stresses in the Si bond coating following exposure. It was found that the TGO phase transformation upon cooling increased compressive stress in the Si bond coating within 15 µm of the TGO.

Press hardening steel (PHS) is the most widely used material in automotive white bodies owing to its excellent formability and low springback. While replacing Ti with Al ensures the hardenability of PHS without compromising its toughness, grain boundary oxidation inevitably occurs during hot-rolled coiling. This phenomenon, driven by the oxygen affinity of alloying elements such as Si and Mn, adversely affects subsequent processing. Current research predominantly focuses on the mechanisms by which Si and Mn contribute to grain-boundary oxidation, whereas the influence of Al has seldom been explored. In this study, tube-sealed heating was employed to simulate the hot-rolled coiling process, specifically investigating the effect of Al on grain-boundary oxidation. The results demonstrate that Al inhibits grain-boundary oxidation through the following mechanisms: Al reduces the oxygen adsorption rate at the scale/matrix interface, thereby lowering the oxidation rate; and Al promotes decarburization and facilitates the enrichment of Si and Mn at the scale/matrix interface. This decarburization accelerates the dissociation of FeO, and the majority of the dissociated oxygen ions combine with the enriched Si and Mn at the interface to form oxides. Consequently, less oxygen enters the steel matrix.

To investigate the effect of recrystallization and pre-aging treatment on the oxidation resistance of alumina-forming austenitic (AFA) steels, the oxidation behavior and related mechanism of a 25Ni15Cr AFA steel under different microstructural conditions were systematically investigated at 1123 K in dry air. The results demonstrated that recrystallization treatment significantly enhanced the oxidation resistance of the AFA steel compared with that of the solid solution-treated sample, whereas subsequent pre-aging treatment failed to provide a further improvement. The recrystallized sample developed a uniform and dense oxide scale composed of fine oxide grains, primarily due to the accelerated diffusion of aluminum facilitated by grain refinement. In contrast, precipitates formed during pre-aging resulted in a negative impact on the oxidation resistance of AFA steel. The B2-NiAl phases caused uneven oxidation of aluminum, while the Laves phases hindered the short-circuit diffusion of aluminum along the grain boundaries of alloy matrix, thereby compromising the uniformity of the oxide scale. Based on the experimental findings, an oxidation model was developed to elucidate the influence of different microstructures on the oxidation mechanisms of the AFA steel.

This paper evaluates the oxidation behavior of T91 ferritic/martensitic steel exposed to flowing oxygen-saturated lead–bismuth eutectic (LBE) with a 90° impact angle at 500 °C, using multiple characterization techniques. Complex multilayered oxide scales with an alternating Fe–Cr spinel-magnetite characteristic were observed under the current condition. This contrasts sharply with the typical double-layered oxide scales observed in static LBE environment, which consist of Fe–Cr spinel and magnetite. More importantly, such multilayered oxide scales in the current condition display a much higher growth rate. After 1000 h of exposure, their thickness reached ~ 32 μm, nearly 1.5 times greater than that in static oxygen-saturated LBE. The accelerated growth is attributed to enhanced oxygen transport, promoted by the penetration of liquid LBE into the interface between the Fe–Cr spinel and the substrate due to partial exfoliation of adjacent oxides. In addition, the formation of abundant crystal defects within the surface region of the substrate induced by the impact of flowing LBE should also play a role. Finally, a possible physical model is proposed and discussed.

The corrosion of 316L steel fabricated by selective laser melting (SLM) and by forging has been studied at 800–900 °C in a H₂/H₂S/CO₂ (Gas I) and a H₂/CO₂ (Gas II) gas mixture providing the same oxygen partial pressure. Both steels behaved protectively in Gas II, while they suffered heavy sulfidation in Gas I, except for the SLM steel corroded at 900 °C, probably due to a larger concentration of grain boundaries, favoring a faster diffusion of chromium to form an external chromia scale. Moreover, the fine-grained microstructure of SLM 316L showed rather good stability after 50-h performance up to 900 °C.

NiCo-based alloys are widely recognized as superior high-temperature self-lubricating materials. Nevertheless, they are prone to failure due to severe oxidation, and the research on solving this issue remains insufficient. In the present work, simple model Ni20Cr–xCo–3Al (wt%) alloys were fabricated by using mechanical alloying (MA) and spark plasma sintering (SPS), and their isothermal and cyclic oxidation behavior at 800 °C in air for 100 h was investigated. Results show that, as the Co content increases, the alloys presented a microstructural change from coarse grain to heterogeneous structure with ultrafine grains surrounding the coarse ones. The alloy containing 30 wt% of Co successfully formed a thinner, flatter, denser and more intact external α-Al₂O₃ scale in both isothermal and cyclic oxidation, exhibiting remarkable oxidation resistance compared with the other alloys. This arises from the favorable balance between elemental diffusion and oxidation, attributed to its heterogeneous structure.

If a rate of metal oxidation is diffusion-controlled, then a thickness of a scale emerging on its surface at constant temperature is typically a parabolic function of time. If temperature changes, then this inherently parabolic temporal evolution of the thickness may transform into differently shaped functions. By using a concept of equivalent times introduced and elaborated in this work, it is shown how the oxide thickness versus time dependence L(t) can be established for any time–temperature profile T(t). Then, it is explored whether there exists a unique T(t) regime for which a growth rate is constant, i.e., for which L(t) is linear. It is proven that it is possible to design a time–temperature scheme for which the same holding times cause identical thickness changes. Such a growth mode, however, cannot be sustained indefinitely; there is a time threshold beyond which the linear growth of the oxide layer cannot be maintained any longer. Although oxidation is frequently a thermally activated process, mathematical expressions and conclusions remain the same for non-Arrhenius kinetics.

The oxidation behavior of AISI 5140 low-alloy steel was investigated under air at oxidation temperatures ranging from 800 to 1100 °C and oxidation times ranging from 5 to 120 min. The microstructure and chemical composition of the oxide layer were characterized, and an oxidation kinetic model was constructed. The oxide layer exhibited a multi-layered structure, with the outer layer consisting primarily of Fe₂O₃, the intermediate layer of Fe₃O₄, and the inner layer comprising FeO and pre-eutectic Fe₃O₄. At the scale-substrate interface, a Si and Cr enriched layer was present. This study employed vertical rolling to descale the surface of oxidized samples; the effect of secondary oxidation on descaling performance was investigated. The results indicated that after the specimens were oxidized at 1200 °C in air, they were subjected to descaling and rolling processes, with a large amount of residual oxides remaining on their surfaces and poor flatness. When the specimens were oxidized at 1200 °C in air and descaled, followed by secondary oxidation at 1000 °C in air, and then subjected to descaling and rolling processes, their surfaces exhibited reduced residual oxides and improved flatness.