# Effectiveness of Nanotechnology Treatments in Composite Aircraft Applications
## 3 Corrosion and Fatigue Test  
The aircraft is capable, according to the CS-VLA rules, of conducting normal-operation takeoffs in no more than a 500 m (1500 ft) ground run and normal-operation landings in no  
Figure 1: Dardo aircraft. more than a 400 m (1200 ft) ground run under the following conditions: (1) field elevation, 0 m (SL); (2) temperature, ISA; (3) airfield surface, dry MOB; (4) take-off weight 750 kg. Furthermore, the aircraft is capable of achieving at least a maneuvering minimum load factor requirement of +3.8 g, \(-\)2.0 g at a basic flying design mass (BFDM) of 750 Kg, and sustain a 10 kts crosswind when taxiing. The complete primary structure is made of carbon fiber. Where useful for weight-reduction purpose and in order to optimize load path, a large use of unidirectional carbon fiber has been introduced. The engine cowlings are made of two parts with carbon fiber. The wing and the fuselage are made as a single item. The complete fuselage, vertical fin included, is made of two half-shell joined together by a longitudinal splice along the upper/lower center line. The wing is made by joining together the main spar, the secondary spar, and the ribs to the wing's upper and lower skins. The wing is attached to the fuselage by four fittings at the main spar and four fittings at the secondary spar. Each fitting is connected to the fuselage by two bolts. The main landing gear structure and its retraction system are fitted to the main spar. Hinges of flaps and ailerons are connected to the secondary spar. The fuel tanks are installed into the wing. A \"Karman\" fairing is accommodating the fuselage and wing profiles. The horizontal empennage is connected to the fuselage by locators, placed at the leading edge. All the movable surfaces are connected to the main structure by aluminum alloy fittings and steel bolts. The phenomenon of corrosion, which occurs in metals, is influenced by numerous and different factors that are related mainly to the operating environment of the component [9; 10]. The following test based on ASTM G31-21 [11] has for objective to investigate the possibility of reducing the corrosion phenomena that could occur in metal parts such as the wing-fuselage attachments, through the use of a new surface coating produced by the 4 Ward360 company, made with nanotechnologies, and comparing it to the currently used primer treatment. The process used for the treatment of the specimens was spray coating, a widely recognized industrial method which involves the application of suspensions of diverse nanoparticles to cover a range of materials with varying shapes [12]. Nanoparticles contained within atomized droplets are applied onto surfaces, resulting in a nanostructured coating once the liquid solvent evaporates. Spray coating offers several advantages over alternative methods, such as minimal liquid wastage, precise control over the film thickness and surface roughness, and the ability to use a wide array of fluids with different viscosities. Its simplicity makes spray coating easily adaptable to large computer-controlled production systems [13]. The most appropriate geometric solution recommended by the standard is the rectangular one; therefore, for the test in question, this type of specimen was modified in shape to create the classic \"dog bone\", so as to be able to cope, after the test of corrosion, with the fatigue test [14]. The dimensions of each specimen can be deduced from Figure 2 and Table 1. The standard specimens were modified by introducing two holes, a central one of 2 mm necessary to increase the stress intensity factor and therefore limit the duration of the next fatigue test. A second hole of 5 mm was present at one end to allow immersion in the corrosion tank. Figure 2: Specim’s geometry definition. Table 2 lists all the specimens subjected to this test with an indication of the specimens subjected to the corrosion process and the specimens which were instead only subjected to the fatigue test. MF000 is the reference for the untreated and uncorroded test specimen.