Manganese oxides (MnO_x), being active, inexpensive and low-toxicity materials, are considered promising water oxidation catalysts (WOCs). This work reports the preparation and the physico-chemical and electrochemical characterization of spin-coated (SC) films of commercial Mn₂O₃, Mn₃O₄ and MnO₂ powders. Spin coating consists of few preparation steps and employs green chemicals (i.e., ethanol, acetic acid, polyethylene oxide and water). To the best of our knowledge, this is the first time SC has been used for the preparation of stable powder-based WOCs electrodes. For comparison, MnO_x films were also prepared by means of electrodeposition (ED) and tested under the same conditions, at neutral pH. Particular interest was given to α-Mn₂O₃-based films, since Mn (III) species play a crucial role in the electrocatalytic oxidation of water. To this end, MnO₂-based SC and ED films were calcined at 500 °C, in order to obtain the desired α-Mn₂O₃ crystalline phase. Electrochemical impedance spectroscopy (EIS) measurements were performed to study both electrode charge transport properties and electrode–electrolyte charge transfer kinetics. Long-term stability tests and oxygen/hydrogen evolution measurements were also made on the highest-performing samples and their faradaic efficiencies were quantified, with results higher than 95% for the Mn₂O₃ SC film, finally showing that the SC technique proposed here is a simple and reliable method to study the electrocatalytic behavior of pre-synthesized WOCs powders.

Anti-ice systems assure a vital on-board function in most aircraft: ice prevention or de-icing is mandatory for all aerodynamic surfaces to preserve their performance, and for all the movable surfaces to allow the proper control of the plane. In this work, a novel multi-functional panel concept which integrates anti-icing directly inside the primary structure is presented. In fact, constructing the core of the sandwich with trabecular non-stochastic cells allows the presence of a heat exchanger directly inside the structure with a savings in weight and an improvement in thermal efficiency. This solution can be realized easily in a single-piece component using Additive Manufacturing (AM) technology without the need for joints, gluing, or welding. The objective of this study is to preliminarily investigate the mechanical properties of the core constructed with Selective Laser Melting (SLM); through the Design of Experiment (DOE), different design parameters were varied to understand how they affect the compression behaviour.

The need for a high-efficiency hot air anti-icing system is met by the use of sandwich panels with high surface area trabecular structures as core. Trabecular structures have good mechanical properties and are able to act as thermal exchange and structural support. A structural characterization of complex trabecular structures made by Additive Manufacturing is required. For this study, AlSi10Mg specimens were produced by Selective Laser Melting technology varying cell shapes (with or without vertical struts), cell sizes (4 and 5 mm) and struts size (1 and 1.2 mm). Compressive tests were performed on the specimens and fracture mechanisms for the two cell types were analyzed by optical microscope observation. The rupture modes of the specimens are strongly dependent on the cell shape as shown by the mechanical results and confirmed by comparison with the Gibson–Ashby model.

There is evidence that Additive Manufacturing (AM) plays a crucial role in the fourth industrial revolution. The design freedom provided by this technology is disrupting limits and rules from the past, enabling engineers to produce new products that are otherwise unfeasible. Recent developments in the field of Selective Laser Melting (SLM) have led to a renewed interest in lattice structures that can be produced non-stochastically in previously unfeasible dimensional scales. One of the primary applications is aerospace engineering where the need for light weights and performance is urgent to reduce the carbon footprint of civil transport around the globe. Of particular concern is fatigue strength. Being able to predict fatigue life in both LCF (Low Cycle Fatigue) and HCF (High Cycle Fatigue) is crucial for a safe and reliable design in aerospace systems and structures. In the present work, an experimental evaluation of compressive–compressive fatigue behavior has been performed to evaluate the fatigue curves of different cells, varying sizes and relative densities. A Design of Experiment (DOE) approach has been adopted in order to maximize the information extractable in a reliable form.

The Fused Filament Fabrication (FFF) process of polyether(ether ketone), PEEK, is a challenging task due to its high melting point and viscosity that imply the need of high temperature of printing and the optimization of many process parameters. In the present work, the influence of printing speed, nozzle and chamber temperature on both crystalline and mechanical tensile characteristics was evaluated. The results showed the possibility to control the 3D-printed PEEK structural properties on which the tensile performances strongly depend. In particular, it was found that the chamber temperature is the parameter that most influences the specimens crystallinity degree which determines their actual tensile behavior. The higher the degree of crystallinity, the stiffer the material is. Furthermore, the printing speed and nozzle temperature play a key role in reducing voids inside the printed parts, thereby increasing tensile strength. In this work, the best tensile performance and the higher degree of crystallinity were obtained by keeping the chamber temperature of 160°C, the nozzle temperature of 450°C and the printing speed of 1500 mm/min. Thus, according to the final application of the printed parts, a careful choice of these parameters is needed.