Ice accretion on external aircraft surfaces due to the impact of supercooled water droplets can negatively affect the aerodynamic performance and reduce the operational capability and, therefore, must be prevented. Icephobic coatings capable of reducing the adhesion strength of ice to a surface represent a promising technology to support thermal or mechanical ice protection systems. Icephobicity is similar to hydrophobicity in several aspects and superhydrophobic surfaces embody a straightforward solution to the ice adhesion problem. Short/ultrashort pulsed laser surface treatments are proposed as a viable technology to generate superhydrophobic properties on metallic surfaces. However, it has not yet been verified whether such surfaces are generally icephobic under representative icing conditions. This study investigates the ice adhesion strength on Ti6Al4V, an alloy commonly used for aerospace components, textured by means of direct laser writing, direct laser interference patterning, and laser‐induced periodic surface structures laser sources with pulse durations ranging from nano‐ to femtosecond regimes. A clear relation between the spatial period, the surface microstructure depth, and the ice adhesion strength under different icing conditions is investigated. From these observations, a set of design rules can be defined for superhydrophobic surfaces that are icephobic, too.
19 March 2021 in The International Journal of Advanced Manufacturing Technology
Recent advances in additive manufacturing (AM) have attracted significant industrial interest. Initially, AM was mainly associated with the fabrication of prototypes, but the AM advances together with the broadening range of available materials, especially for producing metallic parts, have broaden the application areas and now the technology can be used for manufacturing functional parts, too. Especially, the AM technologies enable the creation of complex and topologically optimised geometries with internal cavities that were impossible to produce with traditional manufacturing processes. However, the tight geometrical tolerances along with the strict surface integrity requirements in aerospace, biomedical and automotive industries are not achievable in most cases with standalone AM technologies. Therefore, AM parts need extensive post-processing to ensure that their surface and dimensional requirements together with their respective mechanical properties are met. In this context, it is not surprising that the integration of AM with post-processing technologies into single and multi set-up processing solutions, commonly referred to as hybrid AM, has emerged as a very attractive proposition for industry while attracting a significant R&D interest. This paper reviews the current research and technology advances associated with the hybrid AM solutions. The special focus is on hybrid AM solutions that combine the capabilities of laser-based AM for processing powders with the necessary post-process technologies for producing metal parts with required accuracy, surface integrity and material properties. Commercially available hybrid AM systems that integrate laser-based AM with post-processing technologies are also reviewed together with their key application areas. Finally, the main challenges and open issues in broadening the industrial use of hybrid AM solutions are discussed.
7 August 2009 in The International Journal of Advanced Manufacturing Technology
The evolution over time of wettability properties of super hydrophobic Al2024 developed using an IR-, ns-laser was studied under different storage conditions.