PEO coating containing copper: A promising anticorrosive and antifouling coating for seawater application of AA 7075

Metal products in seawater have to face two important phenomena: corrosion and fouling. Corrosion representsa serious issue that can eventually compromise the integrity of the product. Biofouling, defined as the coloni-zation by organisms (bacteria, algae, plants, and animals) on wetted surfaces, is problematic because it increasesweight and consequently fuel consumption in boats. Moreover, the two phenomena are mutually sharpening.PEO is a quite new surface treatment, which increases corrosion and wear resistance of light alloys much morethan traditional anodizing, and allows the introduction of particles into the coating. In this work, the corrosionand antifouling properties in seawater of copper containing PEO coating, produced on AA 7075, were studied.PEO coatings were produced working at high current densities and in short treatment times, and the particleswere incorporated into the coatings by simple addition to the electrolyte. PEO coatings were also used as pos-sible substrate for commercial painting and untreated samples were tested as comparison. The obtained coatingswere characterized by SEM-EDS, XRD, and potentiodynamic tests. Corrosion and antifouling properties wereevaluatedin situthrough immersion of several samples in seawater for 4 weeks, intermediate collections andanalyses each week with stereomicroscope and SEM observations. The results showed that the PEO coatedsamples containing copper powder exhibited antifouling effect. The use of PEO coating as substrate for paintingcan improve performance both against corrosion and fouling, in presence of defects or damages in the paint

Microstructural and corrosion properties of particles-containing PEO coatings

The Plasma Electrolytic Oxidation treatment (PEO, sometimes also called MAO, Micro Arc Oxidation) has recently attracted great attention due to its capability to create a thick and adherent coating with excellent corrosion and wear resistance. Some of the main characteristics of PEO coatings are the high porosity of the outer layer and the possibility to incorporate directly into the coating particles that are dispersed into the electrolyte. This work will describe the results obtained by inserting metallic and non-metallic particles in PEO coatings produced on magnesium and aluminum alloys. In particular, nano-particles of graphite have been inserted in order to improve the wear resistance and metal particles (copper or silver) in order to give to the samples bactericidal, fungicidal or antifouling propertie

Failure analysis di ruote dentate

Questo studio consiste in una failure analysis di ruote dentate montate su di una macchina agricola soggette a rotture dei denti avvenute in esercizio. Due ruote sono state oggetto di analisi metallografiche, composizionali e fotografiche, nonch\ue9 di prove di micro durezza e di osservazioni al microscopio elettronico. Le analisi fotografiche hanno subito evidenziato una forte usura delle superfici del dente. Nonostante il meccanismo di rottura sia attribuibile alla fatica, non erano visibili le classiche linee di spiaggia sulla superficie di frattura e ci\uf2 probabilmente a causa del basso numero di cicli che hanno portato alla rottura delle ruote dentate. L\u2019analisi della composizione e della microstruttura dell\u2019acciaio non hanno evidenziato criticit\ue0. Erano infatti presenti all\u2019interno del materiale solfuri ma non in quantit\ue0 tale da giustificare il cedimento. In conclusione il materiale delle ruote non presentava anomalie pertanto le cause del cedimento degli organi analizzati erano da ricercarsi in un\u2019errata progettazione degli stessi o in un loro errato montaggio

Pearl formation associated with gymnophallid metacercariae in Mytilus galloprovincialis from the Northwestern Adriatic coast: Preliminary observations

Gymnophallids of the genus Parvatrema are small trematodes infecting waterbirds in their adult stage. Several species of clams and mussels have been found to act as first and second intermediate hosts, in which the trematode larval stages induce the formation of pearls. In this study, a wild population of Mytilus galloprovincialis was sampled along the Northwestern coast of the Adriatic Sea to evaluate the origin and extent of visible pearls. Parasitological investigations, including morphological and molecular analyses, and histopathology were carried out on a representative sample of mussels (n = 158) from June to September 2021. The overall prevalence of infection reached 75.3 %, and the intensity of infection ranged from a few trematodes to thousands per mussel, mostly occurring in the mantle and surrounded by variable numbers of conchiolin layers. Morphological studies allowed classification of the metacercariae as belonging to the genus Parvatrema, and the pairwise comparison of the obtained sequences, encompassing the internal transcribed spacer (ITS) region, revealed a genetic similarity (96.8 %) to Parvatrema duboisi. However, the phylogenetic analysis demonstrated the independent clustering of the obtained ITS sequences compared to other available Parvatrema species. For the relevant commercial impact that pearl formation may have on farmed mussels, ecological and epidemiological aspects of this infection would deserve further investigation in the area

Microstructural and corrosion properties of particles-containing PEO coatings

The Plasma Electrolytic Oxidation treatment (PEO, sometimes also called MAO, Micro Arc Oxidation) has recently attracted great attention due to its capability to create a thick and adherent coating with excellent corrosion and wear resistance. Some of the main characteristics of PEO coatings are the high porosity of the outer layer and the possibility to incorporate directly into the coating particles that are dispersed into the electrolyte. This work will describe the results obtained by inserting metallic and non-metallic particles in PEO coatings produced on magnesium and aluminum alloys. In particular, nano-particles of graphite have been inserted in order to improve the wear resistance and metal particles (copper or silver) in order to give to the samples bactericidal, fungicidal or antifouling properties