Environmental and Economic Impact of an Innovative Biocide-Free Antifouling Coating for Naval Applications.

The work provides an economic sustainability and environmental impact analysis for the validation of a biocide-free antifouling coating for marine applications able to reduce fuel consumption during navigation, CO2 emissions, and the overall environmental impacts associated with shipping, thanks to the reduction of incrustation and the avoidance of biocides release into the water. The results, related to the life cycle of the coating of a motor yacht, with an average sailing life of 25 years, show around 8.8% reduction in overall costs compared to a conventional paint, thanks to a more efficient antifouling action, which reduces the annual fuel consumption by ~13,700 kg/y, or ~9.6%. This leads to a reduction in CO2 emissions, associated with fuel consumption, of ~43.3 ton/y, as well as a lowering of the overall environmental impacts associated with the life cycle of the paint, by almost 10% for the most impactful damage classes, ensuring a greater environmental sustainability of the innovative coating, for the overall service life of the yacht on which it is applied.

Soft Computing Techniques for Laser-Induced Surface Wettability Control.

Making decisions and deducing control actions in manufacturing environments requires considering many uncertainties. The ability of fuzzy logic to incorporate imperfect information into a decision model has made it suitable for the optimization of both productivity and final quality. In laser surface texturing for wettability control, in fact, these aspects are governed by a complex interaction of many process parameters, ranging from those connected with the laser source to those concerning the properties of the processed material. The proposed fuzzy-based decision approach overcomes this difficulty by taking into account both the random error, associated with the process variability, and the systematic error, due to the modelling assumptions, and propagating such sources of uncertainties at the input level to the output one. In this work, the laser surface texturing was carried out with a nanosecond-pulsed laser on the surfaces of AISI 304 samples, changing the laser scanning speed, the hatch distance, the number of repetitions, and the scanning pattern. A significant change of the contact angle in the range 24-121° is observed due to the produced textures. The fuzzy maps highlight the inherent uncertainty due to both the laser texturing process and the developed model.

Environmental and Economic Analysis of FDM, SLS and MJF Additive Manufacturing Technologies.

In this study, the authors present a comparative analysis of different additive manufacturing (AM) technologies for high-performance components. Four 3D printers, currently available on the Italian national manufacturing market and belonging to three different AM technologies, were considered. The analysis focused on technical aspects to highlight the characteristics and performance limits of each technology, economic aspects to allow for an assessment of the costs associated with the different processes, and environmental aspects to focus on the impact of the production cycles associated with these technologies on the ecosystem, resources and human health. This study highlighted the current limits of additive manufacturing technologies in terms of production capacity in the case of large-scale production of plastic components, especially large ones. At the same time, this study highlights how the geometry of the object to be developed greatly influences the optimal choice between the various AM technologies, in both technological and economic terms. Fused deposition modeling (FDM) is the technology that exhibits the greatest limitations hindering mass production due to production times and costs, but also due to the associated environmental impact.

Influence of Thermal Contact Resistance of Aluminum Foams in Forced Convection: Experimental Analysis.

In this paper, the heat transfer performances of aluminum metal foams, placed on horizontal plane surface, was evaluated in forced convection conditions. Three different types of contacts between the sample and the heated base plate have been investigated: simple contact, brazed contact and grease paste contact. First, in order to perform the study, an ad hoc experimental set-up was built. Second, the value of thermal contact resistance was estimated. The results show that both the use of a conductive paste and the brazing contact, realized by means of a copper electro-deposition, allows a great reduction of the global thermal resistance, increasing de facto the global heat transfer coefficient of almost 80%, compared to the simple contact case. Finally, it was shown that, while the contribution of thermal resistance is negligible for the cases of brazed and grease paste contact, it is significantly high for the case of simple contact.