# Effectiveness of Nanotechnology Treatments in Composite Aircraft Applications
## 1 Introduction  
The first studies on nanotechnologies date back to 1959 [1] and today, these technologies are widespread in all sectors. The strong growth in interest and diffusion of these technologies can be well represented by the analysis of the number of scientific articles on the subject in the three major world scientific journals (Nature, Science, PNAS) from 1991 to 2016 [2], or from the analysis of the growth of the \"impact factor\" of the scientific journal \"Nanotechnology\", which, from 2000 to 2020, rose from a value of 1.6 to 3.6 [3]. This strong research footprint has poured into the industrial field with force, exceeding 9000 patents in 2008 [3]. Nanotechnologies have been applied to the transportation sector in order to increase the performance of components on land, air, and sea vehicles. Some examples in the automotive field [4] are the use of nanotechnologies in automotive paints in order to guarantee greater resistance and corrosion prevention; the use of nanotechnologies in order to improve the resistance of surfaces to UV rays; the application of carbon nanotubes as substitutes for metal parts in order to reduce vehicle weight; applications of nanotechnological coatings in the cylinders of internal combustion engine (ICE) in order to reduce friction with relative gains in terms of fuel consumption and a reduction in pollution. In the aeronautical sector [4, 5], at the moment, the number of applications of nanotechnologies is still very low and limited to the coatings sector. As regards the development of new \"light\" materials and/or materials made with innovative technologies, the most promising candidates are polymeric nanocomposites reinforced with carbon nanotubes and boron nitride and epoxy resins reinforced with nanoclays. These materials offer a high ratio between toughness and weight, impact resistance and radiation protection, and the prospect is to develop multifunctional composites. Accordingly, integrated nanosensors for structural health monitoring are also under investigation. Nanostructured metals, on the other hand, find applications in the parts most subject tocorrosion and wear (landing gears, brakes, etc.). Finally, coatings (in the form of thin films), including nanopowders, can be used as self-cleaning or antiglare layers for windows. In [6], different types of nanoparticles, nanofibers, and nanocoating that can be used for reinforcement, surface modification, and property enhancement in FRP composites are presented. In the field of fatigue properties of aluminum alloy materials, in [7], it is shown that an Al-Cu alloy processed using in situ TiC nanoparticle additions coupled with a stir-casting method displays a combination of outstanding mechanical properties in comparison with cast aluminum alloys. A recent review paper [8] explores advancements in corrosion protection techniques for aerospace aluminum alloys, highlighting the transition from conventional methods such as chromate conversion coatings and anodizing to more sustainable and efficient alternatives. Recent developments encompass a spectrum of innovations, including rare-earth element-based coatings, organic-inorganic hybrids, advanced polymer solutions, and the integration of nanotechnology. The literature concerning the use of nanotechnologies to enhance the performance of aerospace materials is certainly lacking in experimental evidence and procedures that quantitatively define their real effectiveness. The present article delves into two specific aspects. Firstly, it examines corrosion phenomena in metals. Nanotech formulations are applied to aluminum alloy specimens via spraying, followed by a post-corrosion fatigue test to assess the treatment's efficacy in reducing corrosion and enhancing fatigue life. The integration of nanotechnology is also compared with classical primer treatments. Secondly, an innovative comparative test to evaluate the \"ease of cleaning\" between untreated dirty surfaces and those treated with nanotechnological formulations is developed.