1,721,094 research outputs found
Atomic layer deposition an innovative technology to improve corrosion and surface functionalities of alloys
No full textWith the fast-growing request for miniaturized electronic components, in the last few decades deposition of nanometric, conformal ceramic, and metallic coatings has been a challenging scientific topic. Atomic layer epitaxy, more recently also known as atomic layer deposition, has proved to be a powerful and flexible deposition technique capable of growing many different oxide and nitride layers onto a wide range of substrates, ranging from metals to polymers. Apart from their potential as semiconductors and electronic materials, chemically stable and defect-free nanometric coatings offer many additional properties of industrial interest, such as wear and corrosion protection. Papers on the potential application of atomic layer deposition outside of microelectronics and semiconductors have known an exponential growth in the last decade and atomic layer deposition has shown the potential to protect substrates from corrosion with a comparable if not superior efficiency when compared to thicker organic or ceramic conventional coatings
Comportamento a corrosione di leghe di alluminio della serie 8xxx impiegate per la produzione di alette di scambiatori di calore
No full textPorous metallic structures for orthopaedic applications: a short review of materials and technologies
No full textCALCIUM SIGNALING: ENCODING AND DECODING
No full textCalcium is a universal second messenger that controls many cellular
reactions. Considering its pleiotropic role, it seems evident that the cells, to
get a specific message in the proper time and manner, need precise and
efficient mechanisms to encode and decode Ca2+ signals. Generally,
extracellular stimuli are converted in a transient increase in cytosolic Ca2+
concentration, [Ca2+]c, which, in turn, modulates cell function. In the last
two decades, improvements in the development of probes and
instrumentation for Ca2+ imaging have led to the discovery that the
coordinated action of different players is responsible for a complex
spatio-temporal organization of the Ca2+ signal. It is intriguing to observe
that cells can encode and discriminate Ca2+ signals not only according to
their magnitude but also according to their localization (microdomains)
and shape; i.e., cells can discriminate between sustained and oscillatory
signals. Even more, in the case of oscillations, messages can be read
differently according to the frequency of the oscillatory signals. The
mechanisms by which cells decode Ca2+ signals are now explored in
numerous laboratories. This article focuses on the autoregulation properties
of the Ca2+ signals. It will show that Ca2+ itself is central in the regulation
of the Ca2+ signal. It will also show that it can act as a first and second
messenger and that it can modulate the activity and the availability of the
other players in the signaling operation
Corrosion behaviour of layers obtained by nitrogen implantation into Boron films deposited onto iron substrates
No full textThe electrochemical behaviour and corrosion resistance of boron films deposited onto Armco iron after bombardment with 100 ke V N + ions were determined in various test solutions. The changes in the electrochemical parameters give evidence of lower anodic dissolution rates for the treated samples. Scanning electron microscopy and Auger analysis of the corroded surfaces confirm the presence of protective layers
Effect of pulse current on wear behavior of Ni matrix micro-and nano-SiC composite coatings at room and elevated temperature
No full textThis work presents the effect of the pulse-current on the wear behavior of Ni/nSiC and Ni/μSiC electrodeposits.
The deposits microstructure and SiC content were investigated by means of microstructural, crystallographic e chemical analysis. The mechanical properties were evaluated through microhardness measurements. Ball-on-disc tests were performed at both room temperature and 300 °C. Wear rate and mechanisms were determined by morphological and microscopical characterization.
The composite-coatings produced under pulse current present enhanced hardness and wear resistance, at both temperatures, linked to microstructural refinement and SiC content. The main wear mechanism observed was triboxidation, accompanied by abrasive wear mainly on the micro-composite coatings
Degradation Mechanisms Occurring in PTFE-Based Coatings Employed in Food-Processing Applications
Full text linkThe application of polytetrafluoroethylene (PTFE) coatings to metal surfaces is a well-known procedure carried out to avoid fouling phenomena on food-processing surfaces. Fluorine-based polymers are generally chemically and thermally stable, thus allowing them to be the preferred choice when designing anti-stick coatings in the food service industry. Their lifespan, however, depends on the environmental conditions. It is well known that thermal ageing can affect the properties of PTFE polymers and reduce their mechanical, thermal, and chemical properties causing failures and contaminating food. The main goal of the study is to identify the different failure mechanisms occurring in PTFE-based coatings, using both SEM/EDXS and ATR FT-IR data to reveal the starting point of degradation phenomena in food processing applications. The results from this research reveal that the preferential points for failures are mainly the polymer/substrate interfaces, the polymer/filler interfaces, or the polymer matrix itself
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