CORROSION BEHAVIOUR OF THE AZ31 MAGNESIUM ALLOY AND SURFACE TREATMENTS FOR ITS CORROSION PROTECTION

Nowadays environmental conservation forces the transportation industry to manufacture lighter and low emissions transport vehicles. In this contest, magnesium alloys have found increasing attention by the automotive industry because of their low density associated with good mechanical properties. However the low corrosion resistance of magnesium alloys in wet environments is still a limiting factor against their widespread diffusion. The aim of this research is both studying the correlation between microstructure and corrosion behaviour of a AZ31 magnesium alloy and developing eco-friendly protective technologies. In particular inhibitors and surface pretreatments with different organic compounds have been investigated. The effect of microstructure on corrosion resistance of AZ31 alloy has been analyzed through a comparative study between the electrochemical behaviour of as-cast and hot rolled AZ31. Environmentally friendly sodium salts of mono-carboxylic acids have been studied as inhibitors of AZ31 alloy corrosion in a standard saline solution. Moreover, long chain sodium mono-carboxylates have been tested as promoters of conversion coatings for this alloy. Finally, significant improvements have been achieved by modifying the protective coatings obtained by 3-mercapto-propyl-trimethoxysilane through cerium nitrate or oxide nanoparticle additions

Improving the Protectiveness of 3-Mercaptopropyl-Trimethoxysilane Coatings on Bronze by Addition of Oxidic Nano- and Microparticles

The protectiveness of coatings based on 3-mercaptopropyl-trimethoxysilane (PropS-SH) applied on bronze artworks was enhanced by investigating and tuning a variety of factors. In particular, the coating performances were optimized by proper additive choice among oxide nanoparticles (CeO2, La2O3, TiO2) and microparticles (fly ash (FA)), and by varying the aging time of the nanoparticle suspensions before coating application and the RT curing time of the coatings. Moreover, the possibility of conservation of the silane solution under refrigerated conditions was assessed. The aggressive environment was a tenfold concentrated synthetic acid rain (AR × 10). The techniques adopted comprised electrochemical tests (polarization curve recording and EIS tests) and SEM-Energy Dispersion Spectroscopy (EDS) observations. In the case of FA microparticles, never used before as additives in silane coatings, further tests were performed in FA suspensions in AR × 10 to clarify the contribution of these particles to PropS-SH coating protectiveness. The tests included pH measurements, elemental chemical analyses, and electrochemical tests on bare bronze. Improved performances of PropS-SH coatings were achieved by La2O3, CeO2, and FA addition, with La2O3 affording the best results during 20 days of immersion. The positive influence of FA was connected to its alkaline character and to the release of soluble silicates

Postural control data from prevalent kidney transplant patients with and without history of falls

From Elsevier via Jisc Publications RouterItem not available in this repository.This article presents data from a research paper entitled “Postural balance, muscle strength, and history of falls in end-stage renal disease patients living with a kidney transplant: a cross-sectional study” available in Journal Gait and Posture [1]. In this article, we reported the minimal detectable changes at the 95% level of confidence (MDC95) of postural balance variables measured in eyes open (EO) and eyes closed (EC) conditions, with a stabilometric platform, in 59 kidney transplant (KT) recipients (mean age= 53.2 ± 11 years). In addition, we also performed receiver operating characteristics (ROC) curve analysis to explore the ability of postural balance measures to discriminate fallers and non-fallers (history of falls: yes or no). Sensitivity, specificity and area under the curve (AUC) of mean center of pressure velocity (CoPv), sway area (SA), center of pressure range of displacement in the anterior-posterior (AP) and medio-lateral (ML) directions were calculated. These data can be used by researchers aiming to design psychometric studies of postural balance in KT patients and they also provide clinicians with information on possible prioritization of outcome assessment for future fall-risk research in this clinical population.31pubpu

B-IMPACT project: eco-friendly and non-hazardous coatings for the protection of outdoor bronzes

Application of protective coatings is the most widely used conservation treatment for outdoor bronzes. Eco-friendly and non-hazardous coatings are currently needed for conservation of outdoor bronze monuments. To fulfil this need, the M-ERA.NET European research project B-IMPACT (Bronze-IMproved non-hazardous PAtina CoaTings) aimed at assessing the protectiveness of innovative coatings for historical and modern bronze monuments exposed outdoors.In this project, two bronze substrates (historical Cu-Sn-Zn-Pb and modern Cu-Si-Mn alloys) were artificially patinated, by acid rain solution using dropping test and by “liver of sulphur” procedure (K2S aqueous solution)to obtain black patina, respectively. Subsequently, the application of several newly developedprotective coatings was carried out and their performance was investigated by preliminary electrochemical tests. In the following stepsof the work, the assessment of the best-performing coatings was carried out and their performance was compared to Incralac, one of the most widely used protective coatings in conservation practice. A multi-analytical approach was adopted,considering artificial ageing (carried out in representative conditions, including exposure to rain runoff, stagnant rain and UV radiation)and metal release, as well as visual aspect (so as to include aesthetical impact among the coating selection parameters) and morphological and structural evolution of the coated surfaces due to simulated outdoor exposure. Lastly, also the health impact of selected coatings was assessed by occupational hazard tests. The removability and re-applicability of the best-performing coatings were also assessed.The best alternatives to the conventional Incralac exhibited were: (i) fluoroacrylate blended with methacryloxy-propyl-trimethoxy-silane (FA-MS) applied on patinated Cu-Sn-Zn-Pb bronze and (ii) 3-mercapto-propyl-trimethoxysilane (PropS-SH) applied on patinated Cu-Si-Mn bronz

Stress-Corrosion Cracking Behaviour of Lean-Duplex Stainless Steels in Chloride/Thiosulphate Environments

The stress-corrosion cracking (SCC) behaviour of two lean-duplex stainless steels (DSS 2304 and LDSS 2404) was studied by slow strain-rate tests (SSRT) in 20% NaCl solution at 80 °C (pH about 6) and in NACE TM-0177 solution at 25 °C (pH 2.7), both in the absence and in the presence of thiosulphate ions (S2O32−). The SCC susceptibility of the two alloys was compared to that of LDSS 2101 investigated in a previous study. LDSS 2404 was always immune to SCC, while DSS 2304 (and LDSS 2101) suffered this corrosion form at specific concentrations. The high SCC resistance of DSS 2404 in both environments was connected to its high Mo content, while the significant SCC susceptibility of LDSS 2101 in NACE TM-0177 solution was likely due to the high Mn content of the alloy

Acupuncture as healing ritual

openLa ricerca muove da alcune questioni sul perché i pazienti ricorrano all’agopuntura, come ci arrivino, con quali conoscenze, aspettative, credenze. Premesso un inquadramento storico di questa pratica, elaborata dalla medicina tradizionale cinese, se ne illustrano i principi di funzionamento. Si indagano le diverse interpretazioni dell’effetto curativo (autosuggestione, neuroscienze, griglia del corpo astrale). Si inquadra il tema con gli approcci della sociologica classica (drammaturgico, interazionista, fenomenologico, teorie della dualità e dell’unità). Si sviluppano i risultati delle interviste, classificando le narrazioni secondo i paradigmi sociologici della malattia (illness, desease, sickness), nonché il tipo di disturbo per cui il narr-attore si rivolge all’agopuntura, come ne viene a conoscenza, le sue aspettative, i risultati, la relazione tra paziente e terapeuta. L’ultimo capitolo è dedicato agli aspetti metodologici

Resistance of Thermally Aged DSS 2304 against Localized Corrosion Attack

In this paper, the effects of thermal aging in the 650–850 C range on the localized corrosion behaviour of duplex stainless steel (DSS) 2304 was investigated. Pitting corrosion resistance was assessed by pitting potential (Epitt) and critical pitting temperature (CPT) determination, while the degree of sensitisation (DOS) to intergranular corrosion (IGC) was evaluated by double loop electrochemical potentiokinetic reactivation (DL-EPR). The susceptibility to stress corrosion cracking (SCC), evaluated in standard NACE TM-0177 solution at pH 2.7 and 25 C, with the addition of S2O3 2 at 103 M, resulted in general good agreement with pitting and IGC behaviour. In fact, as-received DSS 2304 aged for 5 min at 650 C or 750 C presented a high resistance to localized corrosion. The alloy corrosion behaviour was severely impaired with an aging time of 60 min at 650 C and of 10 or 60 min at 750 C, due to the precipitation of finely distributed M23C6-type chromium carbides at ferrite/austenite interphases, which determined the formation of chromium and molybdenum depleted areas. The behaviour of samples aged at 850 C also depended on the aging time, but, at 60 min, the rediffusion of passivating elements produced a recovery of the alloy resistance to pitting, IGC and SCC. Keywords: duplex stainless steel; pittin