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Icing poses significant operational and safety risks in aviation, especially for engine components such as cowls and baffles. This study explores the potential of a chemically exfoliated graphene-rich carbon platelet epoxy coating to improve the anti-icing and de-icing performance of 3003-H14 aluminum alloy, which is widely used in such applications. Chemically exfoliated graphite was incorporated into an epoxy resin, then applied to aluminum substrates. Characterization of the coated samples revealed ~30% improvement in surface Vickers hardness (HV) (HV 75.6 ± 1.15 vs. HV average of 98.3 ± 1.5) and enhanced thermal dissipation, with coated surfaces cooling from 104 °C to 22 °C in 530 s compared to 870 s for uncoated samples. While anti-icing performance was not directly evaluated, the observed improvements in thermal dissipation and surface hardness suggest that chemically exfoliated graphene-rich carbon platelet coatings could be promising for passive anti-icing applications. The literature suggests that graphene coating improves hydrophobicity, reducing ice adhesion and delaying nucleation due to its low surface energy and nanoscale roughness, thereby supporting potential passive anti-icing functionality for aircraft engine components. SEM analysis confirmed a uniform, compact coating layer. These preliminary findings indicate that chemically exfoliated graphene-rich carbon platelet coatings can deliver multifunctional performance—mechanical, thermal, and surface—making them promising candidates for passive anti-icing/de-icing solutions in engine components where conventional systems are ineffective.

This study explores the impact of transfer learning on enhancing deep learning models for detecting defects in aero-engine components. We focused on metrics such as accuracy, precision, recall, and loss to compare the performance of models VGG19 and DeiT (data-efficient image transformer). RandomSearchCV was used for hyperparameter optimization, and we selectively froze some layers during training to help better tailor the models to our dataset. We conclude that the difference in performance across all metrics can be attributed to the adoption of the transformer-based architecture by the DeiT model as it does this well in capturing complex patterns in data. This research demonstrates that transformer models hold promise for improving the accuracy and efficiency of defect detection within the aerospace industry, which will, in turn, contribute to cleaner and more sustainable aviation activities.

Yttrium aluminum garnet thermal barrier coatings (TBCs) deposited by the solution precursor plasma spray process (SPPS) have been shown to have a 200 °C temperature advantage compared to air plasma spray yttria-stabilized zirconia TBCs (Gell et al. in J Therm Spray Technol 27:1-13, 2018). These properties were generated on specimens and included phase stability to 1900 °C, improved sinter resistance, reduced thermal conductivity, and enhanced CMAS resistance. Part I of this paper describes the development of the SPPS processing parameters with different microstructures for three solar engine components (fuel nozzle injectors, annular combustor, and turbine ceramic outer air seals). This Part II paper describes the technology transfer to Solar Turbines Incorporated, coating of the three components and the successful rig and engine tests.

Solution precursor plasma-sprayed (SPPS) yttrium aluminum garnet (YAG) thermal barrier coatings (TBCs) have previously been shown to have higher temperature capability and reduced thermal conductivity compared to state-of-the- art TBCs. This previous work was conducted using a relatively low enthalpy plasma gun (Metco 9 MB) and TBCs were deposited on laboratory specimens. The primary goal of this work was to advance the state of technology readiness of SPPS YAG TBC coatings by using a high enthalpy cascaded arc gun (Sinplex Pro) to produce varied microstructures optimized for specific engine components: a fuel nozzle tip, an annular combustor liner, and turbine ceramic outer air seals. The microstructure and properties of these TBCs have been characterized and shown to be superior to those obtained previously. Based on these favorable results, the processing technology was transferred to solar turbines incorporated. Their process optimization of coatings for the three engine components and the rig and engine testing of the coated components will be described in Part II of this paper.

Wear-resistant sealing coatings of KNA-82 system with 0.1% yttrium addition for hot parts of gas-turbine engines, applied by gas-flame and ion-plasma methods, are considered. The introduction of yttrium increases the operating temperature from 900°C to 1100°C. The methodology of modeling of processes of contact interaction of engine parts under operating conditions has been developed. Tribotechnical tests modeling the contact of the coating surface with the rotor ridge tops and blade feathers have been carried out, after which linear wear has been measured and the results have been statistically processed. The gas-flame coatings show slower wear reduction at temperatures up to 800°C, while both coatings show similar properties at 1100°C. The improved properties are attributed to the formation of phase-like Ni3Y compound in the grain boundaries.

In this work, a hot forming procedure is developed using computer-aided engineering (CAE) to produce thin Ti-6Al-4V sheet components in an effective way. Traditional forming methods involve time- and cost-consuming furnace heating and subsequent hot sizing steps. A material model for finite element (FE) analyses of sheet metal forming and springback at elevated temperatures in Ti-6Al-4V is calibrated and evaluated. The anisotropic yield criterion proposed by Barlat et al. 2003 is applied, and the time- and temperature-dependent stress relaxation behavior for elastic and inelastic straining are modeled using a Zener–Wert–Avrami formulation. Thermo-mechanical uniaxial tensile tests, a biaxial test, and uniaxial stress relaxation tests are performed and used as experimental reference to identify material model parameters at temperatures up to 700 °C. The hot forming tool setup is manufactured and used to produce double-curved aero engine components at 700 °C with different cycle times for validation purposes. Correlations between the predicted and measured responses such as springback and shape deviation show promising agreement, also when the forming and subsequent holding time was as low as 150 s. The short cycle time resulted in elimination of a detectable alpha case layer. Also, the tool surface coating extends the tool life in combination with a suitable lubricant.

With a small oscillatory movement between the contacting bodies held together under the normal load, fretting-related damage and failures are not uncommon in mechanical joints like bolted and gasket joints. One example of a system having multiple bolted and gasket joints, subject to such failures, is the internal combustion (IC) engine. This study aims to provide an overview of different fretting failures observed in the IC engine’s critical components and present an extensive review of various numerical techniques to evaluate fretting failures. Further different important aspects related to fretting fatigue and multiple fretting fatigue initiation methods like critical plane methods, stress invariant methods, continuum damage mechanics-based methods, and fretting-specific parameters are also discussed. Fretting fatigue, being a surface damage phenomenon, is mainly due to the combined interactions between different physics involving tribology contact mechanics, environmental aspects, and materials science; several physical and analytical parameters significant to fretting fatigue damage evaluation are also discussed. Considering the future trend of increasing the power density of IC engines, the importance of critical evaluation of fretting fatigue failures of IC engine components, as a critical requirement for the industry, is proposed towards the end.

Thin-film sensors were used to measure the oil film pressure distribution at the piston pin-bore interface in order to ascertain the stress distribution on the piston pin of a gasoline engine during actual operation. Thin-film sensors have been manufactured by a sputtering method to a total film thickness of about 3–6 μm. The features of thin-film sensors have been utilized to successfully measure the oil film pressure on engine main bearings, connecting rod bearings and piston skirts of both diesel and gasoline automotive engines. However, as engine lubrication conditions have become more severe year by year, it has become necessary to develop thin-film pressure sensors with higher durability. The use of diamond-like carbon (DLC) coating for the protective film of the thin-film sensor has enabled accurate measurement of oil film pressure under engine operating conditions. The AVL EXCITETM Power Unit was used in simulations with the application of elastic fluid lubrication theory. The calculated values were compared with measured data, and a comparison was made of the effect of the model constraint condition.

To improve the accuracy of the calculation analysis of crank journal bearings in motorcycle engines and accurately understand lubrication conditions, the oil film conditions of actual crankshafts and journal bearings should be measured. This research study focuses on the oil film pressure generated in the main bearing, and by using an original thin-film pressure sensor with improved durability achieved through the use of DLC (Diamond-like Carbon), it was possible to perform experiments at a maximum of 13,000 rpm and full load, which was not possible before. This established a method for measuring the oil film pressure generated in the main bearing of a high-speed motorcycle engine during operation without changing the surrounding environment. The maximum oil film pressure was 140 MPa, and the oil film pressure generated by each main bearing was successfully measured under different experimental conditions. The timing of pressure onset agreed well between the calculation and experiment stages, but the peak oil film pressure values were different. By varying the temperature of the engine in the calculation model, the calculated values approached the measured values. In the future, we plan to investigate ways to improve the accuracy of the current analytical model.

Ultra-high temperature ceramics (UHTCs) are generally referred to the carbides, nitrides, and borides of the transition metals, with the Group IVB compounds (Zr & Hf) and TaC as the main focus. The UHTCs are endowed with ultra-high melting points, excellent mechanical properties, and ablation resistance at elevated temperatures. These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles, particularly nozzles, leading edges, and engine components, etc. In addition to bulk UHTCs, UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics. Recently, highentropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials. This review presents the state of the art of processing approaches, microstructure design and properties of UHTCs from bulk materials to composites and coatings, as well as the future directions.