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1

Use of electrochemical impedance spectroscopy to study corrosion of Ni/Al2O3/PTFE composite coatings in NaCl and CMA solutions

Kucharska Beata, Sobiecki Jerzy Robert

Ochrona przed Korozją

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2020

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nr 6

184--188

EN

The main goal of this research was the characterization of corrosion properties of the nickel-nano-alumina-polytetrafluoroethylene (Ni/ Al2O3/PTFE) composite coatings. The layers were produced by electrochemical method in base and modified by organic additive Watts bath. Nickel and Ni/Al2O3 coatings were also produced with the same process parameters and analysed for comparison purposes. The surface topography was evaluated using scanning electron microscopy (SEM). The electrochemical impedance spectroscopy (EIS) was used to estimate the corrosion resistance in two anti-icing environments: sodium chloride (NaCl) and calcium magnesium acetate (CMA). Nyquist and Bode diagrams obtained by the impedance spectroscopy method were established. The equivalent electric circuit and its electrochemical parameters were determined to interpret impedance spectra. The completed studies have shown that the Ni/Al2O3/PTFE composite coatings produced in the base Watts bath are characterized by the best corrosion resistance in a NaCl solution compared to the other investigated coatings. The Ni/Al2O3/PTFE coatings deposited in modified Watts bath has the worst corrosion characteristics in NaCl as well as in CMA environments which is due to their surface development and porosity. The performed studies indicate a different corrosion mechanism in two examined electrolytes.

PL

Głównym celem badań było określenie właściwości korozyjnych powłok kompozytowych nikiel-nano-tlenek glinu-politetrafluoroetylen (Ni/Al2O3/PTFE). Warstwy były osadzane metodą elektrochemiczną w podstawowej i modyfikowanej dodatkiem organicznym kąpieli Wattsa. W celach porównawczych wytwarzano również powłoki niklowe i Ni/Al2O3 stosując te same parametry procesowe. Przy użyciu skaningowej mikroskopii elektronowej (SEM) oceniono topografię powierzchni. Do określenia odporności korozyjnej w dwóch środowiskach odladzających: chlorku sodu (NaCl) oraz octanie magnezowo--wapniowym (CMA) zastosowano elektrochemiczną spektroskopię impedancyjną. Przedstawione zostały uzyskane metodą EIS wykresy Nyquista i Bodego. Do interpretacji widm impedancyjnych wykorzystano elektryczne układy zastępcze i wyznaczone za ich pomocą parametry elektrochemiczne. Przeprowadzone badania wykazały, że powłoki kompozytowe Ni/Al2O3/PTFE wytwarzane w kąpieli bazowej charakteryzują się najlepszą odpornością korozyjną w roztworze NaCl w porównaniu do wszystkich innych badanych powłok. Powłoki Ni/Al2O3/PTFE osadzane w modyfikowanej kąpieli Wattsa mają najgorsze charakterystyki korozyjne, zarówno w środowisko NaCl, jak i w CMA, co jest spowodowane ich rozwinięciem powierzchni i porowatością. Zrealizowane badania wskazują na różny mechanizm korozyjny w dwóch testowanych elektrolitach.

2

Short discussion of static properties of dense polymer melts in two dimensions : CMA Monte Carlo Simulation vs Molecular Dynamics

Polanowski P., Jeszka J. K.

Computational Methods in Science and Technology

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2020

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Vol. 26, No. 4

137-142

EN

In this paper we present the results of an extensive Monte Carlo lattice simulation of two dimensional dense athermal polymer solutions using the Cooperative Motion Algorithm (CMA). Simulations were performed for a wide range of polymer chain length N which varies from 32 to 1024 and for high concentration of polymer. Our results were compared with those obtained by means of molecular dynamics [1].

3

Evolutionary Algorithm for Particle Trajectory Reconstruction within Inhomogeneous Magnetic Field in the NA61/SHINE Experiment at CERN SPS

Wyszyński O.

Schedae Informaticae

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2015

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Vol. 24

159--177

EN

In this paper, a novel probabilistic tracking method is proposed. It combines two competing models: (i) a discriminative one for background classification; and (ii) a generative one as a track model. The model competition, along with a combinatorial data association, shows good signal and background noise separation. Furthermore, a stochastic and derivative-free method is used for parameter optimization by means of the Covariance Matrix Adaptation Evolutionary Strategy (CMA-ES). Finally, the applicability and performance of the particle trajectories reconstruction are shown. The algorithm is developed for NA61/SHINE data reconstruction purpose and therefore the method was tested on simulation data of the NA61/SHINE experiment.

4

Coordianate measurment systems CMM and CMA – characteristic and methods of their accuracy evaluation

Kupiec M

Advances in Science and Technology. Research Journal

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2012

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Vol. 6, nr 16

18--23

EN

The article presents the conception of coordinate measurement. The characteristic of two systems (Coordinate Measuring Machine – CMM and Coordinate Measuring Arm – CMA) which are based on this measurement is also shown. Further on their construction, working principle, application, advantages and disadvantages are described. Finally, the methods of accuracy evaluation of these devices are presented and compared.