Metodologie chemiometriche e loro applicazioni allo studio della corrosione

Scopo di questo articolo è introdurre il lettore all'applicazione di metodologie chemiometriche- nello specifico Design of Experiment (DoE), classificazione e techniche di modelling -che correntemente non sono ampiamente diffuse nell'ambito dello studio della corrosione.Attraverso la descrizione di alcuni esempi sarà dimostrato come queste metodologie possono essere applicatecon l’intento di migliorare la qualità del workflow di un laboratorio di ricerca

Corrosion Behaviour of Al, Cu, and Fe Alloys in Deep Sea Environment

Corrosion Behaviour of Al, Cu, and Fe Alloys inDeep Sea EnvironmentG. Luciano, P. Letardi, P. Traverso, L. BelsantiThe aimof this study is to investigate deep sea environment effects on the corrosion of Al, Fe, and Cu alloys, employedin the KM3NeT project, a deep sea infrastructure designed to host a neutrino telescope. Alloys commonly used inseawater, as well as less widely employed materials were studied. Samples were immersed at the NEMO site (locatedoff Capo Passero, Italy; 3365 mdepth) for consecutive time periods of 6, 12 and 18 months. A representative set ofsamples was recovered and laboratory tests performed to evaluate the type and degree of corrosion attack. Stainlesssteels reported the best performance in terms of weight loss, corrosion rate, and corrosion morphology. However, alsoAl 5093 and Al 6082 performed satisfactorily, in terms of weight loss and corrosion rate. This prescreening will bepartially employed in selecting buildingmaterials for the KM3NeT structure

Improvement in the sustainability and stability of acrylic protective coatings for outdoor bronze artworks

Outdoor bronze artworks are an entrenched part of our urban landscape. They are usually covered by a patina resulting from their exposition to the environment. This patina plays an important aesthetic role and may provide some passivation on the surface, nonetheless it does not prevent the degradation processes promoted by external factors such as pollution, light and humidity. One of the strategies to slow down these unwanted processes is the application of protective coatings. The products currently available have some limitations due to the loss of effectiveness over time and poor environmental sustainability. With the aim of proposing more performing alternatives, coatings based on Paraloid (R) B44 modified with corrosion inhibitors and light stabilizers were prepared and characterized. Two non-toxic corrosion inhibitors were studied, 5-mercapto-1-pheniltetrazole (MPT) and 5-ethyl-1,3,4-thiadiazol-2-amine (AEDTA), comparing them with the traditional benzotriazole (BTA). The approach used aimed to identify the blend providing the most stable coatings. The chemical and physical properties of the coatings, such as colour, solubility, glass transition and composition, were studied and monitored over time. All coatings have shown adequate visual properties; however, corrosion inhibitors degrade some other properties of the coatings and need to be used in conjunction with light stabilizers. The permanence of corrosion inhibitors in the coatings over time was also studied by investigating the role of the support. The establishment of specific interactions between inhibitors and the bronze surface lengthens their permanence in the coatings compared to what happens with inert supports. Especially for AEDTA, the inhibitor retention within the coating and at the coating-bronze interface is better than for BTA and MPT. The effect of each of the additives on the photooxidation stability of the coating was evaluated and the most promising inhibitor and stabilizer combination was identified

Shadow monochromatic backlighting: Large-field high resolution X-ray shadowgraphy with improved spectral tunability

The shadow monochromatic backlighting (SMB) scheme, a modification of the well-known soft X-ray monochromatic backlighting scheme, is proposed. It is based on a spherical crystal as the dispersive element and extends the traditional scheme by allowing one to work with a wide range of Bragg angles and thus in a wide spectral range. The advantages of the new scheme are demonstrated experimentally and supported numerically by ray-tracing simulations. In the experiments, the X-ray backlighter source is a laser-produced plasma, created by the interaction of an ultrashort pulse, Ti:Sapphire laser (120 fs, 3–5 mJ, 1016 W/cm2 on target) or a short wavelength XeCl laser (10 ns, 1–2 J, 1013 W/cm2 on target) with various solid targets (Dy, Ni + Cr, BaF2). In both experiments, the X-ray sources are well localized spatially (∼20 μm) and are spectrally tunable in a relatively wide wavelength range (λ = 8–15 Å). High quality monochromatic (δλ/λ ∼ 10−5–10−3) images with high spatial resolution (up to ∼4 μm) over a large field of view (a few square millimeters) were obtained. Utilization of spherically bent crystals to obtain high-resolution, large field, monochromatic images in a wide range of Bragg angles (35° < Θ < 90°) is demonstrated for the first time

X-ray radiation from ions with K-shell vacancies

Abstract New types of space resolved X-ray spectra produced in light matter experiments with high intensity lasers have been investigated experimentally and theoretically. This type of spectra is characterised by the disappearance of distinct resonance line emission and the appearance of very broad emission structures due to the dielectronic satellite transitions associated to the resonance lines. Atomic data calculations have shown, that rather exotic states with K-shell vacancies are involved. For quantitative spectra interpretation we developed a model for dielectronic satellite accumulation (DSA-model) in cold dense optically thick plasmas which are tested by rigorous comparison with space resolved spectra from ns-lasers. In experiments with laser intensities up to 10 19 W/cm 2 focused into nitrogen gas targets, hollow ion configurations are observed by means of soft X-ray spectroscopy. It is shown that transitions in hollow ions can be used for plasma diagnostic. The determination of the electron temperature in the long lasting recombining regime is demonstrated. In Light-matter interaction experiments with extremely high contrast (up to 10 10 ) short pulse (400 fs) lasers electron densities of n e ≈3×10 23 cm −3 at temperatures between kT e =200–300 eV have been determined by means of spectral simulations developed previously for ns-laser produced plasmas. Expansion velocities are determined analysing asymmetric optically thick line emission. Further, the results are checked by observing the spectral windows involving the region about the He α -line and the region from the He β -line to the He-like continuum. Finally, plasmas of solid density are characteristic in experiments with heavy ion beams heating massive targets. We report the first spectroscopic investigations in plasmas of this type with results on solid neon heated by Ar-ions. A spectroscopic method for the determination of the electron temperature in extreme optically thick plasmas is developed

x ray imaging of bio medical samples using laser plasma based x ray sources and lif detector

This contribution to ECPD2019 is dedicated to the memory of Anatoly Faenov. During a period of approximately thirteen years 1994–2006, Anatoly and his wife Tatiana Pikuz (simply "Tania" for friends), accepting the frequent invitations of the National Institute for Nuclear Physics (INFN) and of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), cooperated with many Italian research laboratories dedicated to EUV and soft X-ray generation, spread in different towns (L'Aquila, Frascati, Milano, Padova, Pisa, Roma, etc.). In spite of the fact that they could stay in Italy only about one or two months per year, their activity was so intense that more than 50 peer- reviewed publications were generated from their experimental and theoretical work (just considering only the results obtained at L'Aquila and Tor Vergata—Rome Universities and at the ENEA Research Center of Frascati), without mentioning the cultural atmosphere that they stimulated in the field of Science and Humanity. The numerous experimental spectra obtained at ENEA by means of their spherically bent mica spectrometers, together with the corresponding theoretical simulations performed in Moscow, allowed to study the changing role of different excitations mechanisms for various plasma conditions, and to characterize at best the ENEA laser-plasma source for different applications: polychromatic and monochromatic micro-radiography of dried biological samples at 1 keV, soft X-ray contact microscopy (SXCM) of living cells in the water-window spectral region, spectroscopy of hollow atoms, etc. In this memorial paper, the main results of biological samples imaging on lithium fluoride (LiF) detectors, obtained with the ENEA and Tor Vergata University laser-plasma sources, are presented. In particular, the improvement of the micro-radiography and of the SXCM techniques obtained after moving from photoresist detectors and photographic films to lithium fluoride (LiF) detectors are discussed, for both dried and wet biological samples

Atomic bonding and thermodynamic properties of pseudo-binary semiconducting alloys

The short-range order of the Cd1-xZnxTe, Hg1-xCdxTe and HgSexTe1-x alloys has been investigated with EXAFS measurements, and a bi-modal distribution of nearest-neighbour bond lengths is found. This behaviour is determined by the minimisation of the bond distortion with respect to the pure compounds, as the authors demonstrate with the use of a thermodynamic model. The same model also allows them to discuss the deviation from the randomness and phase diagrams. The mixing enthalpy hm is determined from the distortion energies of the five tetrahedra which form the basic lattice framework of these solutions. The configurational entropy sm is described by a III-order quasi-chemical approximation using the same tetrahedra as basic clusters. The minimisation of the free energy gm=hm-Tsm determines the equilibrium configuration. The computed distributions of bond lengths in several II-VI and III-V pseudo-binary alloys are in perfect agreement with the experiment and the thermodynamic properties also agree quite well with the existing experimental data. A sharp distinction is made between the behaviour of lattice-matched and lattice-mismatched alloys. The former have a binary-like phase diagram and tend to segregate below the critical temperature. The latter have more structured phase diagrams. In this case the stabilising effect of the elastic strain is outlined and the tendency to form ordered phases is identified