gamma-TiAl alloys face severe hot corrosion degradation in sulfate/chloride environments. This study introduced a novel fluorination and pre-oxidation treatment to enhance the hot corrosion resistance of Al-Si coatings on TiAl alloys. Fluorination combined with pre-oxidation enabled exclusive formation of dense, adherent alpha-Al2O3 scales, bypassing conventional theta-Al2O3 to alpha-Al2O3 transformation that yields defective mixed oxides. The behavior of Al-Si and fluorinated Al-Si coatings after pre-oxidation was systematically compared in Na2SO4 and 75 wt% Na2SO4-25 wt% NaCl molten salts at 900 degrees C. Both pre-oxidized coatings exhibit high Na2SO4 resistance due to effective molten salt blockage by pre-formed scales. The fluorinated Al-Si coating demonstrates significantly enhanced hot corrosion resistance compared to the conventionally pre-oxidized Al-Si coating, attributable to its dense alpha-Al2O3 scale formed during pre-oxidation. During 300 h hot corrosion in Na2SO4 molten salt, the fluorinated Al-Si coating exhibited steady parabolic mass gain kinetics, whereas the unmodified Al-Si coating suffered from cyclic spallation and re-oxidation due to the pre-formed scale defects. NaCl addition accelerated hot corrosion kinetics, triggering rapid Al depletion, interfacial delamination, and non-adherent oxide scale formation. The hot corrosion mechanism of Na2SO4 and NaCl on the pre-oxidized coatings was deeply investigated. These results demonstrate that fluorination is an effective route for accelerating alpha-Al2O3 formation and significantly enhancing hot corrosion resistance of Al-Si coatings, particularly under sulfate-only environments.

The tribological performance and abradability of CoCrAlY-based abradable seal coatings modified with different Ag addition were evaluated through reciprocating sliding wear tests (room temperature and 600 degrees C) and highspeed rubbing tests (350 m/s). The wear morphology, microstructure and phase composition were characterized using three-dimensional laser microscope, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results show that the coating with 10 wt% Ag reduces blade tip wear by over 80%, effectively protecting the Ti2AlNb blade tip. In contrast, 20 wt% Ag addition changes the modification logic and aggravates adhesive material transfer to the blade tip at elevated temperature (600 degrees C) and high rubbing speed (350 m/s). Notably, the incorporation of Ag shifts the dominant high-speed wear mechanism from high-temperature adhesion to deformation-induced abrasion.

TiAl alloys are promising for high-temperature applications but suffer from poor hot corrosion resistance. In this study, a silicon-aluminizing coating and a duplex coating consisting of a silicon-aluminizing inner layer and an yttria-stabilized zirconia (YSZ) top layer were prepared on γ-TiAl alloy. Their hot corrosion behaviors were investigated in Na2SO4 and Na2SO4 + NaCl molten salts at 900 °C. The results showed that both coatings significantly reduced the corrosion rate compared to the bare alloy. The addition of NaCl accelerated the degradation of the silicon-aluminizing coating but had limited effect on the duplex coating. The duplex coating exhibited superior performance due to the YSZ layer, which acted as a physical barrier, preventing direct contact between the molten salt and the inner coating, thereby suppressing the dissolution of the protective Al2O3 scale and Al depletion.

An arc ion plated NiCrAlYSi coating was modified by fluoride treatment with spraying the polytetrafluoroethylene preparation and subsequent thermal diffusion treatment. During the oxidation in air at 950 degrees C, the fluorinated NiCrAlYSi coating rapidly generated alpha-Al2O3 in the initial oxidation stage, skipping the 0-Al2O3 to alpha-Al2O3 transformation due to the fluorine effect. As a result, a more adherent alpha-Al2O3 scale was formed, which significantly improved the long-term service life of the coating. Moreover, the phase transition of thermally grown alumina with and without fluoridation, as well as the effect of fluoride on alumina phase transformation, were discussed.

Quasi-Static Electromagnetic Forming (QSEF) technology utilizes stable magnetic fields generated by long-pulse flat-top currents to achieve non-contact, high-precision forming of large-scale integral aerospace components. To meet the immense energy demands of large-scale component forming, the drive system requires instantaneous power output capabilities at the Gigawatt level. Consequently, the precise regulation of ultra-high flat-top current waveforms becomes a critical challenge for ensuring forming quality. However, traditional meta-heuristic methods, such as Genetic Algorithms (GAs) and Particle Swarm Optimization (PSO), exhibit limited adaptability and robustness when addressing strong geometric nonlinearities induced by workpiece deformation and the performance degradation of pulsed power modules. To address engineering challenges such as capacitor degradation, inductance drift, and module failures, this paper proposes a Staged Deep Reinforcement Learning (Staged-DQN) adaptive current control framework. This framework decouples the discharge scheduling into "heuristic rapid rise" and "DQN fine compensation" stages, adaptively optimizing triggering timing to suppress plateau oscillations and compensate for energy deficits caused by faults. Simulation results demonstrate that under typical high-energy operating conditions, the proposed method achieves superior tracking accuracy compared to traditional PSO in fault-free scenarios. In extreme scenarios involving 25 faulty modules, the Mean Absolute Percentage Error (MAPE) is maintained between 1.13% and 1.80%, significantly lower than the 2.65-3.52% of the baseline DQN. This study validates the effectiveness of the proposed method in enhancing waveform quality and system fault tolerance, offering a reliable intelligent control solution for large-scale electromagnetic manufacturing equipment.

To achieve sustainable and green aerospace propulsion, energy management strategies (EMS) must evolve beyond simple fuel efficiency to address the synergistic optimization of battery health and life-cycle emissions. This paper proposes an eco-friendly multi-objective EMS for turbo-electric hybrid eVTOLs. A unified optimization framework is established to couple conflicting objectives-fuel economy, battery State-of-Health (SOH), and environmental impact. To solve this complex continuous control problem, an improved Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm is developed, incorporating a pyramidal feature extraction structure and state-machine-guided priors to filter noise and accelerate convergence. Simulation results demonstrate that the proposed strategy improves energy economy by 4% over rule-based methods and approaches the global optimum (Dynamic Programming) within a 0.91% margin. Furthermore, Hardware-in-theLoop (HIL) validation confirms real-time feasibility on embedded avionics with an inference latency under 5.5 ms, proving its potential for deployment in sustainable urban air mobility.

Turbo-electric vertical take-off and landing (eVTOL) aircraft impose a critical multi-scale control challenge, necessitating the simultaneous assurance of propulsion energy efficiency and onboard power network stability. Traditional Deep Reinforcement Learning (DRL)-based Energy Management Strategies (EMS) often struggle with safety violations during exploration or rely heavily on manual prior knowledge guidance to ensure convergence. To address these limitations, this paper proposes a hierarchical safety-aware EMS framework. At the supervisory level, a novel Safe Twin Delayed Deep Deterministic Policy Gradient (Safe-TD3) algorithm is introduced to optimize power splitting between the turboshaft engine and the battery pack. Unlike conventional methods dependent on expert rules, the proposed Safe-TD3 intrinsically guarantees system safety through four integrated mechanisms: (1) a pre-execution Safety Critic for risk gating, (2) a Lagrangian relaxation method for soft cost constraints, (3) a correction-as-imitation mechanism to distill safe boundary actions, and (4) state-adaptive exploration noise. At the execution level, a high-fidelity physical model incorporating AC/DC and DC/DC converters with stable electrical control is developed to validate the transient response and bus voltage stability under the high-level directives. Extensive simulations and Hardware-in-the-Loop (HIL) experiments results show that the proposed method achieves near-optimal fuel economy with only a 0.20% gap to the global optimal benchmark DP and exhibits robust zero-shot generalization with a negligible 0.06% performance loss. Besides, it achieves low latency inference capabilities (<8ms) on the embedded platform, which satisfies the real-time performance requirement in turbo-electric eVTOLs.

In the parallel hybrid electric propulsion system (PHEPS), the integrated electric power system serves as an augmenter to the conventional turbomachinery. In order to maximize the performance improvement for the original aeroengine components, this study presents a novel multienergy management control schedule design method for each different flight condition: (1) the minimum variable bleed valve (VBV) strategy under low-thrust setting conditions; (2) the minimum specific fuel consumption strategy under the cruise condition; (3) the active transient motor torque control strategy under the take-off condition; and (4) the equivalent fuel consumption minimization strategy control strategy under the climb or descent condition. Through digital simulation and hardware in the loop simulation based on a parallel hybrid geared turbofan engine (PH-GTF) model, results show that compared with the baseline GTF engine, the PH-GTF propulsion system exhibits significant performance improvements under different flight conditions: (1) 31% reduction in compressor airflow losses with premature VBV closing time during low-thrust operations; (2) 5% and 2% surge margin improvements in the low-pressure compressor during accelerated/decelerated transients through active electric machine torque scheduling; and (3) 18.8% fuel savings under the cruise condition. These results verify the effectiveness and application feasibility of the proposed multienergy management control schedule design method.

This study employs CaF2/BaF2 eutectic as a high-temperature solid lubricant to develop CaF2/BaF2-modified CoCrAlY-based self-lubricating abradable seal coatings (ASCs). Reciprocating sliding wear tests at room temperature and 600 °C, and high-speed rubbing tests (350 m/s), were conducted to evaluate the tribological behavior of three ASC formulations: an hBN-containing reference (0FA) and two CaF2/BaF2-containing variants (10FA, 20FA). At 600 °C, the CaF2/BaF2-containing ASCs reduce the friction coefficient by approximately 50% and the coating wear rate by about 33% compared with the hBN-containing counterpart. In high-speed rubbing tests, the CaF2/BaF2 eutectic is associated with reduced blade-tip material transfer to the ASCs. However, at room temperature, the CaF2/BaF2-containing coatings exhibit a higher wear rate and reduced bond strength owing to the inherent brittleness of the fluoride phase below its ductile-to-brittle transition. These findings suggest that CaF2/BaF2 is a promising high-temperature solid lubricant for ASCs in advanced aeroengine compressors.

Due to porosity and lack of metallurgical bonding, cold-sprayed Ti (CS-Ti) shows insufficient mechanical properties, especially plasticity. Here we investigate the effect of rolling deformation on the microstructure and mechanical properties of CS-Ti. The results show that a 20

To address the challenge of sealing clearance control in high-performance aero-engine compressors, this study developed a novel CoCrAlY-hBN-PHB abradable seal coating system for Ti2AlNb components operating at similar to 650 degrees C. The work systematically investigated the effects of hBN (5-15 wt%) and PHB (2-10 wt%) content on the microstructure and high-speed tribological performance of coatings. The results demonstrate that coating hardness could be effectively tailored through composition design, but excessive hBN (>10 wt%) reduced deposition efficiency and induced anomalous hardening in the 15hBN + 10PHB coating due to in-situ compaction effects. Coating hardness was inversely correlated with abradability. Although the softest 10hBN + 10PHB coating exhibited optimal abradability, its excessively high interconnected porosity could compromise structural integrity and corrosion resistance. Tribological analysis revealed that the superior temperature rise rate of the blade tip caused preferential heat accumulation, generating localized temperatures exceeding 1072 degrees C that triggered B2 phase transformation and material transfer to the coating via microwelding. Concurrently, work hardening of the coating surface further degraded abradability and increased blade wear. The 15hBN + 6PHB composition was identified as the most balanced formulation, though further improvements by architectural grading, hBN/PHB distribution optimization, and blade tip thermal protection are necessary for practical application. This work elucidates the critical thermo-mechanical coupling mechanisms governing Ti2AlNb/coating interactions and provides essential insights for designing next-generation abradable seal coating system.

Both laser thermal softening and in-situ micro-forging can effectively improve the microstructure and properties of cold-sprayed deposition layer. However, each process has its own limitations. In this study, laser thermal softening and in-situ micro forging were simultaneously introduced into cold spray process. The synergistic effects on the microstructure and mechanical properties of AA7075 deposits were examined. SEM, EBSD, and XRD were used to study the microstructure evolution of deposits in details. The results showed that, with 20wt.

The superior oxidation resistance of alpha-Al2O3 necessitates rapid formation on protective coatings. This study introduces a novel fluorination-assisted pre-oxidation method using trace AlF3 to regulate oxide scale evolution on Al-Si coatings. Microstructure of the oxide scale and long-term oxidation behavior of the Al-Si coatings with and without fluorination-assisted pre-oxidation were investigated. The fluorine-modified Al-Si coatings demonstrated superior durability. After exposure at 950 degrees C for 1000 h, the optimized samples showed a minimal mass gain of only 0.873 mg & sdot;cm- 2 and maintained adherent alpha-Al2O3 scales approximately 3.5 & micro;m thick. The formation of TiO2 was suppressed, and internal oxidation was effectively eliminated. In contrast, unmodified coatings developed defective 0-Al2O3-dominated scales during initial oxidation, followed by severe spallation and internal oxidation under prolonged exposure. Mechanism analysis indicates that controlled pre-oxidation at 950 degrees C under fluorine-containing atmospheres revealed profound concentration dependence of AlF3. Optimized AlF3 addition enabled rapid formation of dense alpha-Al2O3-dominated granular scales via gas-phase transport of volatile fluorine-containing species (AlOF/HF). Furthermore, fluorine adsorption exhibits crystallographic plane selectivity, where preferential adsorption on prismatic planes (1210) versus basal planes (0003) drives hexagonal plate-like alpha-Al2O3 formation. This work establishes trace AlF3 addition as an effective strategy for rapid formation of protective alpha-Al2O3 scales in high-temperature protective coatings.

This paper presents a novel WOA-SSA-BP model to improve the measurement accuracy of tunable diode laser absorption spectroscopy (TDLAS) gas detection systems in variable temperature environments. The model integrates the efficient search capability of the Whale Optimization Algorithm (WOA), the local exploration capability of the Sparrow Search Algorithm (SSA), and the powerful data fitting capability of the Backpropagation Neural Network (BPNN), forming a collaborative optimization algorithm architecture. The model aims to achieve precise correction of ethane (C2H6) concentration by accounting for the impacts of three aspects: the variation in gas characteristic spectral line intensity due to temperature fluctuations, the performance instability of infrared light sources, and the electrical property instability of electronic components. The experimental results demonstrate that the WOA-SSA-BP model outperforms the conventional BPNN, WOA-BP, and SSA-BP models. The model exhibits a maximum prediction error of merely 0.29 ppm, alongside an exceptional linear regression coefficient of 0.99998, evidencing its high precision and reliability. Such results suggest that the WOA-SSA-BP model adeptly compensates for the effects of varying temperatures on the TDLAS gas detection system.

This study investigates the application of five machine learning and deep learning methods—CatBoost, LightGBM, XGBoost, MLP, and DNN—for real-time fuel consumption prediction in the turboelectric hybrid propulsion system. The complexity of the system, characterized by high internal coupling, nonlinear dynamics, and multivariable input-output relationships, poses significant challenges for traditional mathematical modeling approaches. Using a dataset of 15,000 real instances of steady-state engine data, we evaluated the performance of each method in terms of Mean Squared Error (MSE) and Root Mean Squared Error (RMSE). Our findings indicate that LightGBM achieves the highest accuracy, while the deep learning methods, particularly DNN, exhibit lower performance due to increased model complexity. In contrast, LightGBM, which has a simpler model, has the best performance, with only a 2.7

The sealing treatment of plasma-sprayed Al2O3 insulating coatings and its effect on the microstructure and dielectric properties were systematically investigated. To compare the penetration depth of sealants, various sealing processes were employed, utilizing two types of sealants and under two different ambient pressures. The microstructure of coatings was analyzed using scanning electron microscopy, energy dispersive spectrometer, and isothermal adsorption/desorption tests. Breakdown strength, resistivity, dielectric constant ( ε_r ), loss tangent ( tanδ ), and complex impedance were measured for both unsealed and sealed coatings. The results indicated that the maximum penetration depth percentage (50.8 ε_r and tanδ of coatings in a 20

Metastable 0-Al2O3 rather than stable alpha-Al2O3 scale is preferentially formed during oxidation between 850 degrees C and 1000 degrees C, which decrease the long-term service life of the coating. In this study, a novel method for promoting the formation of single alpha-Al2O3 through the fluorination modification of a silicon-aluminizing coating on TiAl alloys was proposed. The results indicated that fluorination resulted in notable differences in the oxidation behavior of the coatings. The unfluorinated silicon-aluminizing coating predominantly formed needle-like 0-Al2O3 during the initial oxidation stage while the fluorinated silicon-aluminizing coating facilitated the direct formation of granular alpha-Al2O3 at the initial oxidation stage. The alpha-Al2O3 scale with high thermal stability and good adhesion significantly improved the long-term service life of the coatings. This provides a novel strategy for improving the life of this high-temperature protective coating with alumina as protective scale.

In high-humidity environments, plasma-sprayed Al2O3 coatings exhibit degraded dielectric properties due to water adsorption and proton dissociation on gamma-Al2O3 surfaces. To mitigate this issue, we developed an innovative "electrical stress loading" (ESL) post-treatment for Al2O3 coatings. ESL-induced partial discharges within coating pores modify the microstructural features of pore surfaces. These modifications subsequently alter the water adsorption behavior of the coatings thereby changing their dielectric properties. In the ESL treatment, coatings were subjected to alternating current (AC) electrical stress (4 V/mu m, RMS) at 20 degrees C and 100 degrees C for 30,000 s. Partial discharge characteristics were evaluated via the pulse current method, while microstructural evolution was characterized via scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). After ESL treatment at 100 degrees C, the prepared coatings developed a continuous Al2O5.1C0.45N0.45 amorphous layer on pore surfaces. This layer exhibits reduced sensitivity to water adsorption, particularly chemical adsorption, compared to gamma-Al2O3. Consequently, the coating treated with ESL at 100 degrees C demonstrated a 66.9 % increase in DC breakdown strength and a 66.7 % enhancement in AC (50 Hz) breakdown strength, along with improved resistivity across diverse environmental conditions relative to the assprayed coating.

Cold spraying additive manufacturing (CSAM) Ti exhibits minimal plasticity, posing a significant challenge to its broader application. Heat treatment is recognized as a potent strategy to enhance the mechanical properties of additive manufacturing parts. However, prior investigations have struggled to discern the genuine impact of heat treatment on CSAM Ti due to the high porosity in initial deposits. This study addresses this gap by fabricating CSAM Ti deposits with a low porosity of 2.76 %. The effects of annealing at varies temperature on the microstructure, porosity, and mechanical properties of the deposits were studied. The results show that annealing can promote recrystallization of CSAM Ti and reduce the porosity of CSAM Ti until to 0.77 %. This increases the strength of CSAM Ti to 780 MPa, which even exceeds that of wrought pure Ti. Despite the low elongation of 4.67 %, the CSAM Ti after suitable heat treatment can be used in fields in fields don't require high plasticity.

Aviation is under increasing pressure to reduce carbon emissions in conventional transports and support the growth of low-altitude operations such as long-endurance eVTOLs. Hybrid-electric propulsion addresses these challenges by integrating the high specific energy of fuels or hydrogen with the controllability and efficiency of electrified powertrains. At present, the field of hybrid-electric aircraft is developing rapidly. To systematically study hybrid-electric propulsion control in aviation, this review focuses on practical aspects of system development, including propulsion architectures, system- and component-level modeling approaches, and energy management strategies. Key technologies in the future are examined, with emphasis on aircraft power-demand prediction, multi-timescale control, and thermal integrated energy management. This review aims to serve as a reference for configuration design, modeling and control simulation, as well as energy management strategy design of hybrid-electric propulsion systems. Building on this reference role, the review presents a coherent guidance scheme from architectures through modeling to energy-management control, with a practical roadmap toward flight-ready deployment.