Materials and Corrosion-werkstoffe Und Korrosion最新文献

The degradation of structural materials due to corrosion by the lead–bismuth eutectic (LBE) coolant alloy poses a significant challenge in the development of lead-cooled fast reactors. Grain refinement has emerged as a promising approach to enhance the corrosion resistance of steels, yet its impact on the LBE corrosion behaviour of steels remains underexplored. In this study, the surface grains of ferritic/martensitic T91 steel were refined through shot peening. Corrosion tests were subsequently conducted on both pristine grain (PG) and refined grain (RG) T91 samples in oxygen-saturated liquid LBE at 470°C and 550°C to evaluate their corrosion behaviour. The findings demonstrate that grain refinement significantly enhances the oxidation resistance of T91 steel in liquid LBE. This improvement is attributed to an increased grain boundary fraction, which enhances Cr diffusivity, facilitating the rapid formation of a protective Cr-containing passivation film during the early stages of oxidation. Furthermore, the outer oxide layers on the RG T91 samples exhibit smaller grain sizes and greater compactness compared to their PG counterparts.

The excellent thermal stability and mechanical strength of rare-earth aluminum oxides have garnered considerable interest as a potential thermal barrier coating (TBC) material. In this article, the structural, electronic, and thermal stability of R₃Al₅O₁₂ (R = Ce and Sm) compounds were investigated using the full-potential linearized augmented plane wave (FP-LAPW) approach. The findings indicate that both compounds maintain structural stability under elevated pressure and temperature conditions. Furthermore, the electronic properties reveal that R₃Al₅O₁₂ (R = Ce and Sm) compounds are metallic. The Gibbs2 code was implemented in WIEN2K software to investigate the thermodynamic behavior of R₃Al₅O₁₂ (R = Ce and Sm) compounds under high-pressure and high-temperature conditions. The thermodynamic analysis indicates that Ce₃Al₅O₁₂ exhibits higher structural stability under compressive conditions, making it suitable for high-pressure applications, while Sm₃Al₅O₁₂ has higher entropy and lower Gibbs free energy, making it more suitable for high thermal load environments. The findings suggest that R₃Al₅O₁₂ (R = Ce and Sm) compounds are the most appropriate candidates for the future TBC systems.

In this study, experiments and simulations were conducted to investigate the corrosion mechanisms of refractory and the effects of various parameters on the extent of corrosion. The corrosion status of the refractory was assessed after 2 years of exposure to HF-containing flue gas using compressive strength tests, scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and energy-dispersive spectroscopy. The corrosion mechanism of the silica–alumina-based refractory was also investigated. In addition, a cellular automaton model was developed to simulate the corrosion behavior of the refractory by focusing on the effects of the HF concentration, SiO₂ content, gas diffusion probability, and SiO₂ corrosion probability. A strong positive correlation was observed between these four factors and the extent of corrosion, with the SiO₂ content and HF concentration having the most significant impact. This study provides a theoretical foundation and guidelines for mitigating refractory corrosion in HF-containing environments.

Applying cathodic protection to metal storage tanks prevents corrosion, with protection potential being key but prone to uneven distribution due to influencing factors. This study develops a mathematical model for tank bottoms and uses COMSOL to analyze potential distribution under different anode configurations. Results show ribbon/ring anodes offer superior, more uniform protection but demand higher construction standards. Shallow-buried anodes protect edges better than centers, while deep-well anodes outperform shallow-buried ones in effectiveness. The impact of coating on cathodic protection potential is also studied. Finally, hierarchical dynamic gray relational analysis and analytic hierarchy process quantify factor influences, providing theoretical guidance for optimizing cathodic protection system design.

Oxidation/corrosion analysis of laser beam welded (LBW) Nb-1% Zr-0.1% C (PWC-11) alloy in contact with molten lead-bismuth eutectic (LBE) at 1100°C is yet to be reported. It aims to evaluate the suitability of this alloy as a structural material and address the possible reasons for material loss during this operation. Corrosion study of the weldment (WM) and parent metal (PM) was conducted at 1100°C in LBE solution. The increase in micro-hardness of WM, HAZ and PM can be attributed to the fraction of low-angle grain boundary, formation of βZr (bcc) phase, oxides of niobium and zirconium. βZr phase formation increases the susceptibility towards oxidation. The nitride and carbide phases of niobium and zirconium, and compressive residual stress, improve the resistance towards corrosion. The change in surface roughness of PM and WM was 0.139 and 0.149, respectively. The corrosion rates of HAZ, WM and PM were observed to be equal to 0.25, 0.12 and 0.07 mm/year, respectively. The weight loss%/yr in PM, WM and HAZ were 0.71%, 1.33% and 2.70%, respectively. PWC-11 is recommended as an architectural material for the coolant channels used in a compact high-temperature reactor.

Aluminium alloys (AA) are vital in emerging technologies for their high specific strength. AA7075 has limited corrosion resistance compared to other aluminium alloys and is unweldable by fusion methods. However, Friction Stir Welding (FSW) enables effective welding of AA7075. In this study, 10 mm-thick AA7075-T651 plates were welded using FSW with optimized parameters in a single pass. Mechanical testing and microstructural analysis confirmed sound welds with 74.8% joint efficiency. Plasma Electrolytic Oxidation (PEO) treatment was applied to both base metal and weld samples. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests on untreated samples showed the dynamically recrystallized weld nugget had better corrosion resistance than the base metal. PDP tests confirmed that PEO-treated base and weld samples had reduced corrosion rates and increased corrosion resistance, with corrosion current decreasing by 50% in base and 71% in weld, while polarization resistance increased by 350% and 239%, respectively. EIS analysis confirmed PDP results. Thus, PEO enhances the corrosion resistance of AA7075 FSW welds in corrosive environments.

In this paper, the investigation was carried out for the inhibition property of oleic imidazoline quaternary ammonia salt (OIM) as corrosion inhibitor for under-deposit corrosion (UDC) of X65 steel in CO₂ corrosion environment. Weight loss and In Situ electrochemical measurements were used in an autoclave to study the corrosion behavior of UDC by adding corrosion inhibitor after immersion for a period (pre-corrosion). The results indicated that adding 50 mg/L of OIM corrosion inhibitor at the initial time (0 h) can achieve the best corrosion inhibition effect, with a corrosion inhibition efficiency of 90.3%. With the delay in OIM adding time, the corrosion inhibition effect gradually weakened. In Situ electrochemical results behaved similar to weight loss. The corrosion product layer displayed differently after 72 h corrosion, the condition of adding OIM at different moments. The surface roughness R_a increased with the delay of OIM adding moment, indicating an increase in UDC and reduced protectiveness of layer to the substrate metal. At last, the inhibition mechanism of OIM in the presence of corrosion product layer was proposed.

This study focuses on the corrosion rate prediction of gas field wellbores. Considering the synergistic effect of corrosion factors such as multiphase flow, temperature, pressure, fluid velocity, pH value, microorganisms, and chloride ions, a CPD-well multiphase flow corrosion prediction model, which is based on Norsok M506 model, is constructed by utilizing the corresponding parameters of shut-in wells and production wells. The verification of the predicted corrosion rate is carried out based on MIT logging data of the gas wells. The results show that the determination coefficient R² is between 84.6% and 92.1%. To validate the improved quality, a comparison is performed among the CPD-well, Norsok M506, and De Waard 95 model. Detailed discussions are provided in this study.