Wyniki wyszukiwania - BazTech

1

Adsorption and inhibitive properties of methanol extract of Eeuphorbia Heterophylla for the corrosion of copper in 0.5 M nitric acid solutions

Fouda A. S., Elmorsi M. A., Abou-Elmagd B. S.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 1

95--103

EN

The adsorption and the inhibitive properties of methanol extract of Euphorbia heterophylla on copper in 0.5 M HNO3 have been studied by weight loss method at different temperatures (30-50°C), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Also, the surface morphology was analyzed by scanning electron microscopy (SEM). It was found that the inhibition efficiency increases with increasing extract doses and decreased with increasing temperature. The polarization data revealed that this extract acts as mixed type inhibitor. The adsorption process was more favored at lower temperatures with larger negative standard free energy. The extract was adsorbed physically on the copper surface followed Frumkin isotherm.

2

Odporność zapraw z udziałem popiołów lotnych z kotłów fluidalnych i konwencjonalnych na korozję kwasową

Janowska-Renkas E., Kowalska J., Kaliciak A., Janus G.

Roczniki Inżynierii Budowlanej

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2016

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z. 16

101--109

EN

This paper presents the results of research undertaken to determine the impact of the aggressive environment of acid corrosion on the durability of cement mortars with the participation of fluidized beds boiler fly ashes and conventional fly ashes used separately and in the form of mixtures. The beneficial effect of fluidized beds boiler fly ashes on the physical properties of cement mortars has been shown, i.e. reduction of the contraction, decrease of weight loss and reduction of the destruction of mortars in acid corrosion. This effect was especially beneficial for mortars containing higher (45% by weight) content of fluidized fly ashes, used separately and in the form of mixtures, regardless of the aggressiveness of the environment (1%, 3% and 5% HCl solution).

3

Mechanical properties and corrosion behavior of nitrided surface layer formed on AISI 4140 steel

Jagielska-Wiaderek K., Makrenek M., Mola R.

Ochrona przed Korozją

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2016

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nr 7

248--251

EN

Investigation results under structure and physicochemical properties of glow-discharge nitrided (1:1 vol. N2/H2 atmosphere, 520°C) AISI 4140 steel are presented in the paper. The successive thinning method has been applied to determine the corrosion resistance changes within the cross-section of the nitrided layer. The method consists in step by step polarization corrosion measurements for successive surfacial layers. The potentiokinetic polarization tests were carried out in acidified (pH = 1) 0.5 M sulphate solution. The metallographically prepared specimens were observed with the use of optical microscopy and AFM microscopy. Microhardness measurements of the polished samples from the cross-section were carried out using Vickers indenter and the mechanical properties – using nanohardness meter, CSM, with a load of 80 mN.

PL

W pracy przedstawiono wyniki badań nad budową i właściwościami fizykochemicznymi warstw powierzchniowych stali 42CrMo4 po procesie azotowania jarzeniowego w atmosferze N2/H2 w temperaturze 520°C. Dla określenia zmian w odporności korozyjnej na przekroju poprzecznym warstwy azotowanej wykorzystano metodę postępującego ścieniania, która polega na wykonywaniu polaryzacyjnych testów korozyjnych na coraz głębiej położonych obszarach warstwy wierzchniej. Badania potencjokinetyczne wykonano w 0,5 M roztworze siarczanowym zakwaszonym do pH = 1. Badania metalograficzne prowadzono za pomocą mikroskopu optycznego oraz mikroskopu sił atomowych. Pomiaru rozkładu twardości w warstwie wierzchniej dokonywano metodą Vickersa, a właściwości mechaniczne oceniono przy użyciu nanotwardościomierz firmy CSM stosując obciążenie 80 mN.

4

Kinetics of Corrosion Process in H2SO4 and HNO3 Aqueous Solutions of Lead Free Sn-Ag-Cu Solder Alloys

Guśpiel J., Wierzbicka-Miernik A., Reczyński W.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

559--568

EN

This paper presents the results of the corrosion resistance of Sn-Ag-Cu alloys in air-saturated aqueous solutions containing NO3-, SO42- ions, whose concentration was equivalent to their contents in acid rains and in concentrations 10 - 100 times higher. The Ag, Cu and Sn concentrations in the corrosive media were determined using the Atomic Absorption Spectrometry. The specific dissolution rate and corrosion current were derived using the a rotating disc technique. The corrosion rate of Sn- Ag-Cu alloys depends on pH of the examined solutions and on the concentration of oxygen near the phase boundary. In the whole range of concentrations of the applied H2SO4 + HNO3 mixtures of acids, the pure Sn was more corrosion resistant than eutectic alloy as well as the near eutectic one, following the sequence: Sn>Sn3.66Ag0.91Cu>3.8Ag0.7Cu.

5

Structure, mechanical properties and corrosion behavior of boronized surface layer formed on AISI 321 stainless steel

Jagielska-Wiaderek K., Bala H., Swadźba L.

Ochrona przed Korozją

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2014

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nr 7

248--251

EN

Studies under microstructure, mechanical- and electrochemical corrosion properties of the boronized, AISI 321 acid resistant stainless steel have been presented. The process of the steel surface modification with boron has been carried out in a temperature of 900oC using long-lasting (6 h) gas-contact method in Ekabor-II powder containing potassium fluoroborate (KBF4) activator and alumina (filler). The thickness of the boron-rich layer has been evaluated on the basis of microhardness tests on the cross section of the surface layers. The extraordinary strong hardness of boronized layers is accompanied with a distinct increase in surface roughness and significant development of its area. The electrodes for the corrosion tests had a shape of rotating disks (RDE electrodes). The corrosion behavior of the outer boronized layer has been examined in acidified (pH = 2) aqueous sulphate solution, using potentiodynamic polarization technique. Unlike unmodified steel, the boron-rich outer layer does not passivate but undergo fast dissolution both in active- and transpassive regions in the corrosion solution.

PL

Przedstawiono wyniki badań mikrostruktury, właściwości mechanicznych i korozyjnych powierzchniowo naborowywanej, kwasoodpornej stali nierdzewnej typu X6CrNiTi18-10. Proces modyfikowania powierzchni stali za pomocą boru przeprowadzano stosując długotrwałą (6 h), kontaktowo-gazową metodę nasycania w mieszaninie proszkowej zawierającej Ekabor-II, fluoroboran potasu (KBF4) jako aktywator i tlenek glinu (wypełniacz). Grubość warstwy wzbogaconej w bor oceniano na podstawie testów mikrotwardości na przekroju poprzecznym modyfikowanych warstw stali. Niezwykle wysokiej twardości warstwy naborowanej towarzyszy znaczna jej porowatość i rozwinięcie powierzchni. Badania korozyjne wykonane z użyciem wirujących elektrod dyskowych. Zachowanie korozyjne zewnętrznej, naborowanej warstwy oceniono w zakwaszonym (pH = 2), siarczanowym roztworze wodnym, stosując polaryzacyjną technikę potencjodynamiczną. W przeciwieństwie do niemodyfikowanej stali, wzbogacona w bor jej warstwa zewnętrzna nie pasywuje się w roztworze korozyjnym, ale ulega szybkiemu roztwarzaniu zarówno w zakresie aktywnym jak i transpasywnym.

6

Corrosion inhibition of mild steel in HCl solution by Tinidazole

Reza I., Saleemi A.R., Naveed S.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 1

67-71

EN

Tinidazole, a pharmaceutical compound has been investigated with reference to the inhibition of mild steel acidic corrosion in 1 molar HCl by means of weight loss and electrochemical measurements. The outcomes attained at 30°C revealed that the Tinidazole had obtained 90% inhibition efficiency at 400 ppm concentration. These results explain that the inhibition process occurs by means of adsorption. The inhibitor molecules adsorb on the surface of the metal, following Langmuir's adsorption isotherm. Potentiodynamic polarization measurements established that Tinidazole is an inhibitor of a mixed type. An appropriate equivalent electric circuit for modeling and the analysis of impedance data to give a better explanation of the process of corrosion inhibition have been proposed.