Search Results (6)

The adoption of chrome-free anodizing and sealing systems for aluminum alloys, particularly AA2024, is gaining prominence due to environmental and health concerns associated with traditional Cr(VI)-based processes. This study evaluates the environmental and economic impacts of sulfuric acid anodizing (SAA) combined with sealing based on fluorozirconate, molybdate, and cerate. Comparative analyses were conducted against conventional Cr(VI) systems and SAA with Cr(III) sealing, focusing on corrosion resistance, energy consumption, washing steps and material flows. The entire anodizing process was examined, including pretreatment, anodization, and sealing. Electrochemical analyses and surface characterization through SEM/EDS, FIB, and XPS were conducted. The results demonstrate that the chromium-free system offers competitive corrosion resistance while significantly reducing environmental and economic costs. Furthermore, fluorozirconate, molybdate, and cerate-based post-treatments broaden its application spectrum in corrosion science and warrant further exploration. However, adopting new sealing technologies in aerospace requires extensive certification involving corrosion resistance, durability assessments, and stringent environmental simulations. Compliance with regulatory standards set by the FAA (Federal Aviation Administration) and EASA (European Union Aviation Safety Agency) necessitates thorough documentation, third-party validation, and testing to ensure safety and performance before industrial implementation. These challenges underscore the complexity of transitioning to more sustainable anodizing and sealing technologies in the aerospace industry. Full article

This paper aims to evaluate the thermal decomposition temperature and linear thermal expansion coefficient of typical non-metallic materials in aero-engine components. Thermogravimetric analysis and thermomechanical analysis were employed to systematically investigate the thermal and dimensional stability of these materials at varying heating rates, and their performance was validated through fireproof experiments. It was found that the high-strength graphite gasket exhibited the highest thermal decomposition temperature, while the polytetrafluoroethylene and fluorosilicone rubber showed excellent dimensional stability. Fluorine-based materials, such as fluorine rubber, showed higher thermal decomposition temperatures but relatively poor dimensional stability. This paper provides a scientific basis for the selection and design of sealing materials in aero-engines, contributing to the improvement of equipment safety and reliability. Full article

The rapid development of the aviation industry has put forward higher and higher requirements for material properties, and the research on smart material structure has also received widespread attention. Smart materials (e.g., piezoelectric materials, shape memory materials, and giant magnetostrictive materials) have unique physical properties and excellent integration properties, and they perform well as sensors or actuators in the aviation industry, providing a solid material foundation for various intelligent applications in the aviation industry. As a popular smart material, piezoelectric materials have a large number of application research in structural health monitoring, energy harvest, vibration and noise control, damage control, and other fields. As a unique material with deformation ability, shape memory materials have their own outstanding performance in the field of shape control, low-shock release, vibration control, and impact absorption. At the same time, as a material to assist other structures, it also has important applications in the fields of sealing connection and structural self-healing. Giant magnetostrictive material is a representative advanced material, which has unique application advantages in guided wave monitoring, vibration control, energy harvest, and other directions. In addition, giant magnetostrictive materials themselves have high-resolution output, and there are many studies in the direction of high-precision actuators. Some smart materials are summarized and discussed in the above application directions, aiming at providing a reference for the initial development of follow-up related research. Full article

Care for the natural environment, which can be observed in the tightening of emission standards, has enforced the search for new fuels, especially renewable sources of natural origin. The article presents the results of theoretical and experimental considerations on the impact of aviation biofuels on the materials used for sealing flange joints. The fuel type selected for the test is compatible with aviation fuels. Fuels have been enriched with a bio-additive that changes the technical and physical properties of the fuel. The tested gaskets were made of soft, aramid-elastomeric materials that were flat in shape and without reinforcement. Their commercial names are AFO and AFM. Tests were carried out with the use of a simple flange joint with a fuel reservoir at 373 K. Both fuel loss and the pressure drop on the gasket were measured during a 1000 h period of time. The experiments showed that the seals preserved the technical parameters in the presence of the tested fuels. The fuel loss did not exceed the accepted limits, which demonstrates the suitability of the tested materials for utilization with new types of fuel. However, no unequivocal conclusions can be drawn about the positive or negative impact of bio-additives on the sealing material due to the fact that both an improvement and deterioration in tightness under certain circumstances were observed. Based on the experimental data, a mathematical model was proposed that makes it possible to predict the service life of the gaskets in flange joints in contact with the investigated types of fuel. The potential application of the research results is practical information about the impact of biofuel on the gasket, and hence the information about the possibility of using traditional sealing materials in a new application—for sealing installations for the production, transmission and storage of biofuels. Full article

Due to the hydrodynamic pressure effect, the bearing capacity of the oil film on the surface of a textured friction pair is greater than that of a smooth surface. In this paper, the effects of PTFE surface texture parameters (shape, depth, width, and area ratio) on the oil film bearing capacity and leakage of the sealing system under lubrication are studied using the FLURNT simulation. It is found in this present study that greater texture depths do not necessarily lead to better sealing performance. When the texture depth exceeds a certain level, a reverse flow occurs at the bottom of the texture, thereby weakening the hydrodynamic pressure effect. An optimal texture depth of 5–10 μm maximizes the oil film bearing capacity. Within a certain range, the oil film bearing capacity increases along with texture widths. In addition, leakage of the rectangular texture rises significantly with growing texture widths. Larger texture area ratios result in higher leakage, but the bearing capacity first rises and then falls with an increase in the area ratio, with a maximum value of 70–80%. Considering the influence of texture parameters on oil film bearing capacity and leakage, selecting the most appropriate texture parameters for surface texture treatment optimizes the performance of the sealing system. The findings of this paper provide a theoretical basis for improving the sealing performance of high-end aviation equipment using texture treatment, thereby enabling the application of surface texture technology to improve the tribological properties of materials. Full article

The internal transport of medical goods in a hospital heavily relies on human resources that carry the materials on foot. Such mode of transport may be affected by inefficiencies, e.g., due to bottlenecks, and other logistic challenges. Thus, it may benefit from the use of unmanned aircraft systems in several aspects. Such a scenario introduces specific criticalities for healthcare organizations in densely populated areas and below congested airspace, such as the Milan metropolitan area. The authors applied a co-creation methodology to design a highly automated drone service for the delivery of pharmaceuticals at San Raffaele Hospital, Milan, Italy. The needs of the main users were identified by means of semi-structured interviews and visualization material. Based on those outcomes, a drone service was designed and validated with the main users. It emerged that the main gain point of such a service would be increasing hospital logistics efficiency. The risks tied to the operations (e.g., tampering of the delivery container) were evaluated and appropriate mitigations were identified (e.g., use of tamper-evident seals or mechatronic locks). The information required by the digital system offering the needed logistics functions was analyzed for future development. Recent conceptual and regulatory advancements in the field of Urban Air Mobility (UAM) in Europe were elaborated to outline the digital ecosystem in which aviation and non-aviation actors would exchange information to ensure operations’ efficiency, safety and regulatory compliance. Full article