bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence and Thermoluminescence Properties of Eu2+ and Ce3+ Activated BaAlSi5O2N7 Phosphors
Authors: Fartode S.A. , Singh Vijay , Dhoble S.J.
Published: January 2015

Ce3+ and Eu2+ activated BaAlSi5O2N7 phosphors have been prepared by the modified three step solid state diffusion method. Prepared phosphors are characterized by XRD, SEM, photoluminescence and thermoluminescence techniques. Upon excitation at 234nm, Ce3+ activated BaAlSi5O2N7 phosphor shows strong emission at 360nm. Upon excitation at 348nm, Eu2+ activated BaAlSi5O2N7 phosphor shows strong emission at 469nm in the blue region of the optical spectrum. After quenching at higher temperature and upon excitation at 363nm, BaAlSi5O2N7:Eu2+ phosphor shows broad band at 516nm in the green region of the optical spectrum. The trap parameters are studied using glow curve deconvolution. It was found that the obtained samples may be suitable for near UV excited white light emitting diodes.
Electroluminescence in Organically Capped Cd1-xZnxSe Chalcogenide Nanocrystals
Authors: Gautam Nitendra Kumar , Ramrakhiani Meera , Kuraria R.K. , Kuraria S.R.
Published: January 2015

Currently there is a great interest in II–VI semiconductor nanoparticles, particularly organically capped soluble particles of cadmium or zinc sulphide and selenide, for their ready to use application in devices. For electroluminescence (EL) devices, it is expected to cover a broad spectrum and to tune various specific colours by preparing Cd1-xZnx Se instead of CdSe and ZnSe. Ternary alloys have composition dependent properties; therefore Cd1-xZnxSe has attracted much attention in the fields of luminescence and optoelectronic devices. It has wide optical band-gap and good stability with respect to environment. In this study, Cd1-xZnxSenanoparticles have been synthesized by using starch as a capping agent through a chemical synthesis route at room temperature. Samples have been prepared varying composition factor ‘x’ in ternary alloy Cd1-xZnxSe. Cubic structure of all has been confirmed by XRD. Crystallite size calculated from XRD was found in the range of 3-5 nm and it was observed that size reduces on increasing Zn content in ternary compound. Optical absorption spectra showed the blue shift in absorption edge with increasing Zn content. Band gap has been obtained by absorption studies and increase in band gap observed on increasing Zn content in the compound. Electroluminescence studies reveal that lower threshold voltage is required for samples with lower ‘x’ value. The Brightness increases on increasing the voltage above threshold voltage and the variation pattern is almost exponential for all samples. The voltage-current curve represents ohmic nature of the EL cell. Impedance was found to increase on increasing ‘x’ value. The increase in EL intensity is faster for higher frequency. EL spectra revealed that light emission is in violet-green region corresponding to band gap for both Cd0.75 Zn 0.25Se and Cd0.5 Zn 0.5Se, with a slight blue shift on increasing Zn content. A ternary system Cd1–xZnxSe, may be engineered better for application purpose by suitably choosing the composition parameter ‘x’.Contents of Paper
Synthesis and Electroluminescence of Silver Doped ZnS/PVK Nanocomposite
Authors: Dwivedi Amrita , Dwivedi Nisha , Gautam Nitendra , Ramrakhiani Meera , Khare P.K.
Published: January 2015

Sulfide based luminescent materials have attracted a lot of attention for a wide range of photo-and electroluminescence applications. Among the sulfides, ZnS is promising host material for development of phosphors in different visible emission bands. Doping of Ag can affect the electroluminescence of the host material. Incorporation of host ZnS into the polymer matrix is one of the best method to display their special functions, which stabilize the nanoparticles. Here we report a synthesis and electroluminescence of silver doped ZnS/PVK nanocomposites thin films. Reported films were prepared by using chemical route with varying Ag doping and ZnS loading in the composite. Structural and morphological characterization were carried out through XRD and SEM techniques, which confirmed the particles in nanoregime. Though optical absorption spectra and band gap of ZnS semiconductor nanoparticles in ZnS:Ag/PVK matrix were estimated, and using EMA model, particle size was calculated which supports the results of XRD. Electroluminescence of nanocomposite samples was studied and it was found that threshold voltage depends on doping of Ag and also on loading of ZnS. Voltage brightness characteristics support the production of EL by acceleration-collision mechanism.Contents of Paper
Persistence Mechanisms and Applications of Long Afterglow Phosphors
Authors: Shanker V. , Haranath D. , Swati G.
Published: January 2015

This article presents a broad review of long persistence (LP) materials that are a special kind of photon energy storage and conversion materials. They are also known as long afterglow phosphors or long decay phosphors (LDP). These phosphors can be readily excited by any ordinary household lamp, sunlight and/or ambient room lights and glow continuously in the dark for hours together without involving any radioactive elements. It is the modifications that are made to crystalline host lattice that exhibit these unusual properties related to persistence due to effective doping of some transition or rare-earth ions. A slight variation in the processing parameters such as type of reducing atmosphere, stoichiometric excess of one or more constituents, the nature of fluxes, and the intentional addition of carbon or rare-earth halides can drastically shift the emission colors and persistence times of the LP phosphors in the visible spectrum. Historically, Cu-doped ZnS phosphor had been a traditional LP material with its afterglow time less than an hour. The emission color of these LP phosphors was confined between green and yellow-green region only. However, synthesis of blue and red-emitting phosphors with long persistence times had been always a challenging task. This review article covers the recent advances in the blue, green and red-emitting LP phosphors/nanophosphors, persistence mechanism involved and the basic problems associated with their luminescence efficiency and persistence times. Modifications to existing nanosynthesis protocols to formulate a nontoxic Green Chemistry Route are also presented.Contents of Paper1. Long Afterglow Phosphors
Corrosion Resistance in Saline Environment of Colored Based Alumina Spectrally Selective Surfaces
Authors: Bogatu Cristina , Cazan Cristina , Manciulea Ileana , Duta Anca
Published: January 2015

The paper presents the results on accelerated corrosion/erosion tests, of Thickness Insensitive Spectrally Selective paints, based on alumina matrix infiltrated with inorganic oxide pigments used in the solar-thermal energy conversion. The mechanism of the corrosion/erosion process is presented and discussed based on the polarization Tafel curves obtained in NaCl 3.5% solution. Optical properties (solar absorptance and thermal emittance) were measured before and after the corrosion tests and the results were correlated with the sample’s morphologies and the corrosion parameters. The influence of the antireflection layer on the corrosion resistance and spectral selectivity is also discussed.
The Effects of Inappropriate Corrosion Protection
Authors: Janczewski Michał
Published: January 2015

The effectiveness of corrosion protection depends on several complex processes connected with the development of the construction, such as:
The Effect of Ti and REE Addition on the Corrosion Resistance of the AlZn12Mg3.5Cu2.5 Alloy in "Acid Rain" Environment
Authors: Michalik Rafał , Woźnica Henryk
Published: January 2015

A significant problem associated with the use of high-strength aluminum-zinc alloys is their insufficient resistance to corrosion. A often used method of improving the resistance to corrosion is plating, resulting in a decrease of their strength. Improving the corrosion resistance can be achieved by application of micro - alloying elements. Titanium and rare earth elements are particularly interesting micro - alloying elements. Subject of examination were AlZn12Mg3.5Cu2.5 base alloy (without micro-alloying) and alloy with the addition of titanium alloy and alloy with the addition of rare earth elements. Corrosion examinations were carried out in a solution of "acid rain", pH = 3.5. The scope of the research included potentiodynamic and potentiostatic tests , examination of the surface and structure of the samples after corrosion.The research found that the addition of titanium does not cause a significant improvement in corrosion resistance of the AlZn12Mg3.5Cu2.5 alloy. A significant improvement was achieved with the addition of rare earth elements. It was found that corrosion tested alloys is local and leads to the formation of pits.
Corrosion Resistance of AA2024-T3 Coated with Graphene/Sol-Gel Films
Authors: Hernandez Miguel , Genesca Juan , Ramos Claudia , Bucio Emilio , Bañuelos José Guadalupe , Covelo Alba
Published: January 2015

Graphene is a two-dimensional network of carbon atoms with optimal thermal, electronic and chemical stability properties that promise different and versatile applications in various fields including the protection of metals from corrosion phenomena. For this reason in this paper graphene was employed and studied as an agent dopand incorporated into hybrid sol-gel coatings to enhance their resistance in saline media and to improve the durability of these films. Graphene was obtained by using an electrochemical method involving oxidation and reduction reactions in a sodium lauryl sulfate solution. On the other hand, the hybrid sol-gel was synthesized from the combination of inorganic and organic precursors, zirconium (IV) n-propoxide (TPOZ) and 3-glycidoxipropiltrimetoxysilane (GLYMO) respectively. In order to obtain the coating system (graphene/sol-gel) two different procedures were applied onto clean aluminum plates: a) the electrodeposition of graphene and b) the graphene-doped sol-gel coating. Differential scanning calorimetry, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the results, which demonstrate an improvement of the corrosion properties of the films with the incorporation of graphene compounds.
Epoxy-Polyelectrolite Composites as a Basis of Intellectual Coating for Protection from Underfilm Corrosion on Cathodically Polarizable Structures
Authors: Petrov Nikolay N. , Koval Tatyana V. , Falina Irina V. , Gorokhov Roman V. , Sheldeshov Nikolay V. , Bukov Nikolay N.
Published: January 2015

In this paper substantiated the possibility of creating on the basis of epoxy-polyelectrolyte composites of anticorrosive coatings sensitive to corrosive environment and its application for protection from underfilm corrosion cathode-polarized structures, which include, for example, underground steel pipelines.
Properties of Functional Epoxy Coatings Modified by Carbon Nanoparticles
Authors: Diblíková Linda , Koukalová Alena , Kudláček Jan , Zoubek Michal , Herrmann František
Published: January 2015

Properties of commercially available epoxy coating were modified using multi-walled carbon nanoparticles (MWCNT) to obtain functional coating with improved abrasion resistance. Simultaneously, corrosion resistance of the epoxy resin could not be negatively affected by the particles addition. Composite coatings with various MWCNT content were prepared and evaluated with regard to their function by abrasion and corrosion tests. We found out that the abrasion resistance of the coatings increased with increasing amount of CNT particles in the matrix. Corrosion protection properties of pure epoxy coating as well as its adhesion were slightly improved by adding 0.5 and 1 wt% MWCNT.
Solid State NMR and EIS Examination of SiO2-Epoxy Hybrid Coatings on Stainless Steel
Authors: Masalski Jan , Wawrzaszek Urszula , Potrzebowski Marek J. , Kucharczyk Barbara , Chęcmanowski Jacek G. , Tylus Włodzimierz , Szczygieł Bogdan
Published: January 2015

Sol-gel SiO2 and hybrid films were deposited on 316L stainless steel by the dip process. Epoxy bisglycidyl hydroquinone (EBH) was used as an organic component in hybrid films. Both coatings were uniform and homogeneous and displayed good adhesion to the substrates. The thickness of hybrid coatings was greater than that of SiO2 coatings. Thermal condition preparation has significant influence on spectroscopic properties of samples. These features are due to changes of morphology of epoxy-silica hybrid compared to unmodified silica-gels and are related to decomposition at higher temperature. The corrosion behaviour of 316L stainless steel samples coated with SiO2 and hybrid films was studied in Ringer’s solution by electrochemical impedance spectroscopy. SiO2 and silica-based hybrid coatings produced by the sol-gel method offers a good protection against corrosion of stainless steel in Ringer’s solution. In contrast to the SiO2-coated samples and the hybrid coating heated to 200°C, the behaviour of the hybrid coating heated to 300°C changed from resistive to a barrier-like one during exposure to the solution. This change was found to be a transient effect only. During 1-month exposure to Ringer’s solution the coating lost its barrier properties.
Anticorrosive Property of Potassium Dichromate Film on Galvanized Coating in Distilled Water
Authors: Adetunji Olayide , Aiyedun Peter Olaitan , Bello Oladimeji Suleiman
Published: January 2015

Hot Dip Galvanized (HDG) coating protects steel from corrosion by providing a thick, tough metallic zinc envelope, which completely covers the steel surface and seals it from the corrosive action of its environment. The anti-corrosion ability of this sacrificial anode cathodic protection can be improved upon through the protective nature of passivation films on zinc like potassium dichromate.This study investigated the anti-corrosion effect of potassium dichromate (K2Cr2O7) film on freshly galvanized coating in distilled water (pH=7.92). The K2Cr2O7 film passivity on the hot-dip zinc coated steel sheets (taken as treated in the context of this study) was used in direct comparison with their untreated counterparts. The test was run for 30 days at 120 hours interval during which the corresponding weight losses, corrosion rates, inhibitor efficiencies, and pH of the final solutions were obtained of the coupons. Analysis of results was made using Microsoft office applications. The surface morphology of the samples was obtained using Optical microscope. The results obtained revealed the greater influence of the action of the K2Cr2O7 film on selected and examined HDG steel sheets corrosion performance. Weight losses increased with increase in immersion time. Inhibitor efficiency of 4.1% was achieved. The photomicrographs confirmed the occurrence of corrosion on untreated coating more than the treated ones. Conclusively, potassium dichromate was effective in passivating galvanized coating from white rust.
Electrodeposition of Zinc Coatings from Ionic Liquid
Authors: Nieszporek Daria , Simka Wojciech , Matuszek Karolina , Chrobok Anna , Maciej Artur
Published: January 2015

The electrochemical deposition of zinc coatings from 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) baths on steel substrate was described in this paper. The influence of [ZnCl2]/[BMIMCl] ratio, current density as well as temperature have been investigated. It was found that electrodeposition in all of tested baths and parameters allowed to obtain zinc coatings. The surface of coatings were matte and in the most of cases the coating morphology was not homogenous. On the basis of corrosion investigation it was pointed out that application of the baths of higher ZnCl2 content are more beneficial for zinc coatings electrodeposition that the one of [ZnCl2]/[BMIMCl]= 2:3.
Influence of Plastic Deformation on the Corrosion Behaviour of As-Cast AlMg2 and AlCu4Mg1 Aluminium Alloys in NaCl Solution
Authors: Vignal Vincent , Krawiec Halina , Szklarz Zbigniew
Published: January 2015

The influence of plastic deformation on the corrosion behavior of as-cast AlMg2 and AlCu4Mg1 aluminum alloys was studied at the microscale using the Electrochemical Microcell Technique and surface microgauges. It was shown that large strain gradients develop locally. The corrosion behavior of both alloys was affected by plastic deformation. The most active sites contain large strain gradients in AlMg2 and cracks with damage in the matrix in AlCu4Mg1.
Microplasma Oxidation of Magnesium Alloy AZ91D by Impulse Current
Authors: Nawrat Ginter , Wierzbińska Małgorzata , Wieczorek Tomasz , Nieużyła Łukasz , Krząkała Agnieszka , Maciej Artur , Simka Wojciech , Raga Krzysztof
Published: January 2015

In this work the results of investigations on thickness distribution of conversion coatings on magnesium alloy AZ91D obtained by plasma electrolytic oxidation (PEO) in sodium silicate solution are presented. The morphology and chemical composition as well as thickness distribution of obtained coatings, with special respect to hard to reach points are shown. Also the corrosion resistance of obtained alloy samples is determined.
XPS Study of Surface Layer Formed on AISI 316L after High-Current Density Electropolishing
Authors: Rokosz Krzysztof , Hryniewicz Tadeusz , Rzadkiewicz Sławomir
Published: January 2015

In the paper, there are presented XPS results of surface layer formed after electrochemical polishing of AISI 316L (EN 1.4404) stainless steel at high current density of 2000 A/dm2. For the investigation, electrolyte based on orthophosphoric (H3PO4) and sulfuric (H2SO4) acids in proportions 3:2, was used. The obtained results have shown, that high current density has considerably influences the composition of passive layer formed after electrochemical treatment. The study was focused mainly on the amount of carcinogenic nickel, sensitization chromium compounds on the sixth degree of oxidation as well as the [(Cr+3.3∙Mo)/Fe] coefficient.
Evaluation of the Growth Mechanism of Ti-Containing Conversion Coatings Using XPS
Authors: Tylus Wlodzimierz , Winiarski Juliusz , Szczygieł Bogdan
Published: January 2015

Ti-containing coatings as chromate replacement were prepared on electrogalvanized steel. Zinc coatings were deposited from a weak acid chloride bath. Cr-free conversion coatings were deposited from bath composed of: TiCl3, H2SiF6, H2O2 and oxalic acid. XPS was used to evaluate chemical composition of the coatings as a function of deposition time. Deposited coating were of conversion type. Regardless of the achieved conversion coating thickness, Zn from the substrate was always present. In the coatings were identified: Zn2SiO4 / Zn4Si2O7(OH)2, ZnTiO3, ZnO, Zn (OH)2, Zn0, SiOx and Ti-O-Si in varying proportions. The chemical composition of the outer surface of the coating depended on deposition time, e.g. in a time interval 0-300 s 30 fold increase of the Si:Ti ratio and 20 fold of the Si:Zn ratio were observed. Estimated thickness of conversion coating was 3, 14, 35, and 100 nm for the time deposition of 1, 40, 80 and 300 s respectively. It is the proposed model for distinguishing Zn (0) phase from Zn (2+) quantitatively, based on the Zn L3M45M45 spectrum. The composition of the ZnTiSi conversion coating determined its mechanical properties and corrosion resistance. Standard tests carried out showed that the coatings obtained at the time of 20-40 s had the best corrosion performance and mechanical resistance
Corrosion Resistance of Cerium Based Silane-Zeolite Coatings on AA6061 Alloy
Authors: Caprì Angela , Calabrese Luigi , Bonaccorsi Lucio , Proverbio Edoardo
Published: January 2015

In the present work we analyzed the anti-corrosive properties, on AA6061, of sol-gel silane-zeolite hybrid coatings doped with cerium nitrate ions as inhibitor. Three different types of composite coatings were prepared by using cerium doped zeolite and/or silane matrix. For each type, four formulations, varying the zeolite amount (in the range 60-90% wt), were tested. All composite coating evidenced a high homogeneity and good adhesion performances. Cerium addiction in the coating formulation did not compromise the hydrophobic properties of the coating. Furthermore the addition of the cerium ions improved the anti-corrosion properties of the composite films inducing a significant stability of the electrochemical behavior.
Thermally Sprayed Coatings as Corrosion Protection for Steel Structures – Influence of the Manufacturing Processes on the Coating Quality
Authors: Maghet Teodora , Mährlein Jörg , Wilhelm Thomas , Sallai Monica , Friedrich Susanne , Regenspurger Romy , Feser Ralf
Published: January 2015

The use of technical construction parts in corrosive environments frequently leads to costly damage and sometimes to a loss of the functionality of the component parts. Particularly to be noted in this regard are steel structures exposed to industrial and maritime weather conditions (e.g. steel towers, tower flanges for the wind energy industry, primarily in coastal and offshore regions, supports and arch parts used in bridge construction, etc.). These require an especially high corrosion resistance.
Zirconium Modified Aluminide Coatings Obtained by the CVD Method
Authors: Romanowska Jolanta , Zagula-Yavorska Maryana , Góral Marek , Sieniawski Jan
Published: January 2015

The paper presents the comparison of the structures of the zirconium modified aluminide coatings deposited on pure nickel by the CVD and method for different conditions, that is the gas flow and the time of deposition. The time of the aluminizing processes varied from 1.5 to 10 hours and the gas (HCl) flow varied from 0.4 to 1.4 l/min. Aluminum was deposited from the AlCl3 and zirconium from the ZrCl3 gas phases at 1040 oC. The obtained coatings were examined using an optical microscope (microstructure and coating thickness) a scanning electron microscope (chemical composition on the cross-section of the modified aluminide coating) and an XRD phase analyzer. Microstructures and phase compositions of coatings obtained at different process parameters do not differ significantly. In all cases, it is a triple zone structure. Chemical compositions of zones correspond to β-NiAl, γ’-Ni3Al and γ-Ni (Al) phases. The elongation of the time of zirconium-aluminizing process from 1.5 to 10 hours leads to the increase of the coating thickness from 30 to about 60 μm. The EDS analysis and concentration profiles of the cross-section of the coating showed the nickel outward diffusion from the substrate and the aluminum inward diffusion from the surface to the nickel substrate. In coatings deposited at a slow gas flow porosity was observed on the border between β-NiAl and γ’-Ni3Al layers. In coatings deposited at fast gas flow, zirconium does not form any inclusions but dissolves in the matrix. The Kirkendall porosity was not observed.
Study of Interaction between Liquid Magnesium Alloy and Glassy Carbon Particles
Authors: Olszówka-Myalska Anita , Chrapoński Jacek
Published: January 2015

In the presented experiments, the influence of a liquid magnesium alloy with Zr and RE reinforced on glassy carbon particles (GCp) in composites obtained by the mechanical mixing of a suspension, its pressureless solidification and by pressure die casting was examined. The microstructure of the as-received GCp and after their isolation from the composite was characterized by SEM and EDS methods. The presence of a thin oxide type layer with a high RE content was found, independent of the applied composite technology.
Corrosion Inhibition of Concrete Steel-Reinforcement in Saline/Marine Simulating-Environment by Rhizophora mangle L.
Authors: Okeniyi Joshua Olusegun , Loto Cleophas Akinloto , Popoola Patricia Abimbola
Published: January 2015

Corrosion inhibition of concrete steel-reinforcement in 3.5% NaCl, simulating saline/marine environment, by the leaf extract of Rhizophora mangle L. was studied in this paper. For this, duplicated specimens of steel-reinforced concrete slabs, admixed with different concentrations of the leaf extract, were immersed in the corrosive test-medium. Analyses, as per ASTM G16-95 R04, of the electrochemical test-results identified 0.0833% Rhizophora mangle L., per weight of cement, with optimal inhibition efficiency η = 95.73±0.15%. The study established a decrease in inhibition effectiveness as concentration of Rhizophora mangle L. increases.
Influence of the Crystallographic Orientation of Grains and Plastic Deformation on the Electrochemical Behavior of Pure Aluminum in Sodium Chloride Solution
Authors: Szklarz Zbigniew , Krawiec Halina , Wróbel Mirosław
Published: January 2015

In this paper, the influence of the crystallographic orientation of grains on the corrosion behaviour of pure aluminium is investigated combining the Electrochemical Microcell and the X-Ray Diffraction (XRD) Techniques. Crystallographic orientation has strong influence on the current density in the cathodic branch and the breakdown potential. The influence of plastic deformation (compression) on the corrosion resistance is also investigated. Compression has nearly no influence on the current density in the cathodic domain, but improves the corrosion resistance of aluminium in sodium chloride solution.
Deterioration of Cement Composites with Silica Fume Addition due to Chemical and Biogenic Corrosion Processes
Authors: Eštoková Adriana , Kovalcikova Martina , Luptáková Alena
Published: January 2015

The paper is aimed at comparative study of resistance of Portland cement composites with addition of silica fume as durability increasing factor in various aggressive environments (sulphuric acid with pH 4, the medium of activated bacteria and the cultivating medium without bacteria) during 150 days under model laboratory conditions. Experimental studies confirmed: the leaching of silicon ions calculated to 1 g of concrete sample affected with bacteria Acidithiobacillusthiooxidans was 2.5 times lower (31.78 mg/g of sample) for concrete sample with silica fume addition comparing to concrete sample of ordinary CEM I Portland cement without any additives (82.98 mg/g of sample). The highest concentration of calcium ions released (60.808 mg/g of sample) was observed for reference sample without silica fume addition placed in the cultivating medium. Silica fume based concrete samples were found to have better performance in terms of calcium ions leaching for all environments and silicon ions leaching.
The Influence of Waste Expanded Perlite on Chemical Durability of Mortars
Authors: Pichór Waldemar , Barna Magdalena , Kapeluszna Ewa , Łagosz Artur , Kotwica Łukasz
Published: January 2015

Degradation of building materials is an important phenomena influencing its design and utilization. Corrosion of concrete, due to common use of this material is especially important. Chemical corrosion of cementitous materials may be mitigated using various methods. Among them introduction of properly chosen active supplementary cementitous materials to the mix is one of most commonly used. One of possible additives possessing pozzolanic properties is ground waste expanded perlite. No data on the influence of such perlite on chemical durability of cementitous materials can be found in literature. Present paper presents results of investigation on the influence of ground waste expanded perlite on chemical durability of cement mortars. Results obtained showed that there is an improvement of durability of mortars modified with ground waste expanded perlite in sodium sulfate enviroment.
Corrosion Behavior of Hybrid Organic-Inorganic Coated Steel in Simulated Concrete Pore Solution
Authors: Criado María , Sobrados Isabele , Bastidas José Maria , Sanz Jesús
Published: January 2015

This work compares the anticorrosion features of polysiloxane hybrid films deposited on carbon steel substrates by dip-coating. To assess the influence of the components, sol-gel coatings were prepared from condensation and polymerization of TEOS and MPTS, TEOS and MTES, TMOS and MPTS or TMOS and MTES in three molar ratios. The corrosion resistance of the coatings was evaluated by means of polarization curves and the coatings’ thicknesses and compositions were analyzed by a field emission-scanning electron microscopy.
Bio-Corrosion of Fibrous Cement Boards and Cement Composites
Authors: Harbuľáková Vlasta Ondrejka , Eštoková Adriana , Luptáková Alena , Kovalčíková Martina
Published: January 2015

The paper deals with the comparative study of bio-corrosion of fibrous cement boards and Portland cement composites. Fibre-cement flat boards are widely used materials in the Slovak Republic for exterior and interior cladding, as fibre-cement slates for roofing and cladding and as fibre-cement corrugated sheets for roofing and cladding. Bio-corrosion of studied materials has been simulated in laboratory conditions during 80 days. Effect of sulphur-oxidizing bacteria Acidithiobacillusthiooxidans on the specimens was investigated. The bio-deterioration processes have been manifested by leaching of main cement components as well as by surface changes. The calcium and silicon contents in leachates were evaluated during the experiments using X – ray fluorescence method (XRF).
Concluding the results of the concrete’s biodeteriogens influence on the analyzed samples (fiber boards and cement composites) more extensive leaching of calcium ions from the cement matrix was confirmed as assumed by bacteria influence when compared to the abiotic environment. Mixture of white compounds on the samples surface was identified by SEM microscopy and XRD analysis as sulphate products (ettringite, thaumasite, gypsum). Shift of pH of liquid media to alkaline region up to 7.2 due to alkaline products leaching were noticed for all studied samples.
Sulphur Species Corrosivity in Refinery Feed Stock
Authors: Suleiman Mabruk I.
Published: January 2015

High temperature sulphide corrosion and equipment failures have been reported in several crude and condensate processing facilities of petroleum refineries. Affected materials were carbon and low alloy steels operated in temperatures ranging from 200 to 300°C.These failures were attributed to specific sulphur species and were not anticipated by corrosion prediction tools used for their material selection. The corrosion mechanisms of these species are not fully understood. This paper presents Takreer Research Centre (TRC) research work for isolating the active sulphur species responsible for the corrosion. Two condensate samples were first analysed for total sulphur, hydrogen sulphide (H2S), Mercaptans (RSH) and other impurities. Using Gas Chromatograph with Sulphur Chemilumenesence Detector (SCD), it was possible to identify Mercaptans and sulphides from the process samples. Laboratory corrosivity testing of condensate sample using carbon steel and low alloy steel coupons at 275°C indicated that the corrosion rate was mainly related to the Mercaptans species within the Total Sulphur. The results concluded that specific dissociation temperature of respective Mercaptans is a useful tool in predicting the possibility and extent of corrosion and its vulnerable process loop.
The Corrosion of HDG Zinc Coatings on the Road and Urban Infrastructures
Authors: Królikowska Agnieszka , Komorowski Leszek
Published: January 2015

The standard ISO 14713-1 shows that HDG coatings should protect steel in the corrosive atmosphere C5 for 10–21 years. It was observed that pitting corrosion appears already after 2–3 years on roads and urban infrastructures and both Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) have shown that lead inclusions were present in all such corroded zinc coatings. The laboratory prepared HDG coatings with different amount of lead inclusions were investigated by gravimetric method (after exposure in salt chamber), SEM with EDS, and Glow Discharge Optical Emission Spectrometry (GDOES). The corrosion resistance was analyzed in the polarization tests and local probe techniques. The inclusions could accelerate coating corrosion because lead is cathodic to zinc.
Comparison of Human Health and Safety Loss due to Corroded Gas Pipeline Failure in Rural and Urban Areas: A Case Study in Malaysia
Authors: Hanafiah Norhamimi Mohd , Zardasti Libriati , Yahaya Nordin , Noor Norhazilan Md , Safuan Ahmad A.
Published: January 2015

Consequence assessment is an integral part of the risk assessment process. There are many types of consequences loss due to pipeline failure such as asset loss, environmental loss, production loss, and human health and safety loss (HHSL). This paper studies the comparison of HHSL between rural and urban areas due to pipeline failure subject to corrosion. The damage area of the explosion was calculated using Aloha software by considering the details of the selected sites such as atmospheric and topographical conditions. The HHSL was calculated using a mathematical equation of quantitative risk assessment in terms of the number of fatalities or injuries or both. The results of the assessments from rural and urban areas were then compared with one another to identify any significant dissimilarity. This study shows that there was a possibility to improve the decisive value of risk by implementing the proposed approach in consequence assessment in Malaysia.
Investigation of the Degradation Mechanism of Platinum-Rhodium Catalytic Wires during Oxidation of Ammonia Process
Authors: Pura Jarosław , Kwaśniak Piotr , Wiecinski Piotr , Garbacz Halina , Zdunek Joanna , Laskowski Zbigniew , Gierej Maciej
Published: January 2015

In our investigation we focused on effects of the degradation of Pt-Rh gauzes from three different industrial catalytic systems. The aim of the study was to compare the degree and the mechanism of degradation under different conditions (pressure, temperature, gas flow direction). The investigation was performed on about 80μm diameter wires after long (6 months) exposition to chemically aggressive environment. Microscope observations and microtomography analysis showed that all wires surfaces were strongly developed by etching and deposition processes occurring under extreme conditions. Each wire differed in rate of degradation and morphology of the characteristic cauliflower-shape growths. Also differences in elements distribution on both, surface and cross sections, were observed. Obtained results can be basis of further investigation on improvement of endurance of PtRh alloys in high temperature chemical application.
Atmospheric Corrosion Protection of Metallic Structures Using Geocements-Based Coatings
Authors: Kryvenko Pavlo V. , Guzii Sergii , Al-Musaedi Hameedi Abdullah Jafar
Published: January 2015

It is known that load-bearing metallic structures that are in service in the atmospheric conditions showed that are exposed to corrosion. The known-in-the art paint-and-lacquer protective coatings can provide protection of metal surfaces for a rather short period between 5 to 10 years. That is why these structures should be protected by the more advanced coatings of new generation, namely: geocement-based coatings which differ from the known-in-the-art binding materials by formation in the hydration products of the zeolite-like minerals and feldspathoids. The paper discusses substantiation of choice of geocement composition in the (хК, уna)2O⋅Al2O3⋅nSiO2⋅mH2O system, target synthesis of hydration products of the geocements matrix in the fields of dynamic cavitation, optimal parameters of cavitation treatment aimed at nanostructurization of the geocements matrix in order to synthesize zeolite-like and hydromicaceous phases, choice of appropriate hardening agents and fillers etc. for producing highly efficient protective coatings with high corrosion resistance, high adhesion to metallic substrate and durability.
The Influence of Temperature on Erosion Resistance of Carbide Coatings Deposited by APS Method
Authors: Sosnowy Pawel , Góral Marek , Kotowski Slawomir , Hanula Grzegorz , Gwizdała Jakub , Drzał Jakub , Kobylarz Marcin , Borowski Przemysław , Gargała Rafał
Published: January 2015

The carbide coatings are widely used for wear and erosion protection of different materials. In present paper the WC/Co coatings were deposited by a single-cathode Sulzer Metco F-4 plasma gun. The microstructure and thickness measurements were conducted. The erosion test was conducted using a Koechler Air Jet Errosion tester at the temperature of up to 500oC. The procedure was similar to ASTM G76 standard. Changes in erosion resistance of coating into different temperature were observed.
Microstructural Phenomena Occurring during Early Stages of Cavitation Erosion of Al-Si Aluminium Casting Alloys
Authors: Dybowski Bartłomiej , Szala Mirosław , Kiełbus Andrzej , Hejwowski Tadeusz
Published: January 2015

The researches have concerned cavitation erosion of AlSi7Mg and AlSi11Mg aluminium casting alloys. The alloys have been investigated in the as-cast condition and after the precipitation hardening. The cavitation erosion tests were performed using vibratory cavitation erosion equipment in 5 minutes. Resistance to cavitation of tested materials was estimated by means of MDE (mean depth of erosion) parameter according to ASTM G32. After the cavitation tests eroded surface of the specimens has been observed by means of scanning electron microscopy. The roughness of the surface was measured on profile contact tester. The best resistance for cavitation erosion exhibited AlSi7Mg alloy after heat treatment, the weakest AlSi11Mg alloy in as-cast condition.
The Effect of Pre-Hydrogen Charging on Corrosion Behaviour of Superduplex Stainless Steel Welded Joints
Authors: Łabanowski Jerzy , Świerczyńska Aleksandra , Michalska Joanna
Published: January 2015

The paper presents results of research undertaken to determine the influence of hydrogen on passivity and corrosion resistance of 2507 super duplex stainless steel welded joints. Butt welded joints were made with low heat input using flux corded arc welding (FCAW) method. Coupons of 5.0 x 5.0 mm were cut from the welded joints containing weld metal (WM), heat affected zone (HAZ) and parent metal (PM). Hydrogen was introduced into the samples by cathodic current method under galvanostatic condition at room temperature. Corrosion resistance was qualified with the polarization curves registered in synthetic sea water. Electrochemical hydrogen charging affected the native passive layer. The internal hydrogen shifted corrosion potential to the more active direction and cause an increase in corrosion current density. The corrosion sensitivity increases for higher current density applied during hydrogen charging. Weld metal area has been revealed as the most sensitive to corrosion attack.
The Influence of Deformation the Corrosion Resistance of Titanium Grade2
Authors: Zwolińska Marta , Sotniczuk Agata , Topolski Krzysztof , Królikowski Andrzej , Garbacz Halina
Published: January 2015

Severe Plastic Deformation (SDP) processes including Hydroextrusion (HE) causes the change of the mechanical properties by the introduction of a large number of defects and significant refinement of the microstructure. During the initially stages of HE microstructure becomes more elongated according to the extrusion direction. Only after a certain deformation, grains become more equiaxed. Present studies are intended to determine the influence of the titanium Grade2 microstructure and grain size distribution on its corrosion properties. All corrosion tests were conducted in a 0.9 % NaCl solution at room temperature. Electrochemical Impedance Spectroscopy (EIS) was measured after 2 and 24 hours. Also Potentiodynamic Polarization was conducted after 24 hours. Microstructures were reviled using Scanning Electron Microscopy and Transmission Electron Microscopy. Grain size distribution was determined using the program Micrometer . The results confirmed formation of titanium dioxide and very good corrosion properties of titanium Grade2 at all stages of hydrostatic extrusion.
Nickel Electrode Precursor Covered by Pt, Ni and Pt/Ni Layers Using Sol-Gel Method
Authors: Jaroń Artur , Żurek Zbigniew
Published: January 2015

The presented paper discusses a possibility of developing and modifying surface of nickel substrate by applying of Ni, Pt, Pt/Ni porous metallic layers by zol-gel method using EDTA as a complexing agent. Then gel containing Pt or Ni or Ni/Pt was decomposed during pyrolysis process and then transformed into the porous metal during oxidation/reduction process at 600°C respectively in air or H2 atmosphere. The thermal decomposition of gels were studied by TG/DTA method. Compositions of oxidized as well as metallic layers were determined by EDX and XRD method. The morphology of Pt, Ni and Pt/Ni layers were studied by SEM method.
Inhibition of Steel-Rebar Corrosion in Industrial/Microbial Simulating-Environment by Morinda lucida
Authors: Okeniyi Joshua Olusegun , Loto Cleophas Akinloto , Popoola Patricia Abimbola
Published: January 2015

This paper studies inhibition of steel-rebar corrosion in concrete immersed in 0.5 M H2SO4, simulating industrial/microbial environment by the leaf extract of Morinda lucida. Electrochemical monitoring methods were employed for testing different concentrations of the leaf extract admixed in duplicated specimens of steel-reinforced concrete slabs immersed in the acidic test-system. Statistical analyses as per ASTM G16-95 R04 of the experimental results showed that effectiveness of Morinda lucida at inhibiting concrete steel-rebar corrosion increased with the concentration of the admixture. 0.4167% Morinda lucida, per weight of cement, was identified with optimum inhibition efficiency η = 98.78±0.34% followed in effectiveness by 0.3333% Morinda lucida with η = 93.20±1.76% at inhibiting steel-rebar corrosion in the corrosive test-environment.
Growth of Acidithiobacillus thiooxidans Biofilm on Glass, Concrete and Stoneware
Authors: Dec Weronika , Cwalina Beata , Michalska Joanna , Merkuda Daria
Published: January 2015

Biofilms formed by various microorganisms are often responsible for microbiologically induced corrosion of materials exposed to moisture. Many bacteria strains may form biofilms on different mineral materials including concrete and stoneware. Among them, the sulfur-oxidizing bacteria of Acidithiobacillus genus, especially of A. thiooxidans species play an essential role in these materials' destruction. In the present study we observed comparable intensity of A. thiooxidans growth on concrete and glass, and slower biofilm formation on stoneware. Prolongation of incubation time caused an increase in biomass of A. thiooxidans biofilm formed on glass and stoneware. Amongst the investigated mineral materials, the concrete proved to be the most susceptible to deterioration by A. thiooxidans bacteria.
Differences between A. thiooxidans and A. ferrooxidans Biofilms Formed on Concrete and Stoneware
Authors: Dec Weronika , Cwalina Beata , Michalska Joanna , Parzentna Anita
Published: January 2015

Sulfur-oxidizing bacteria (SOB) of Acidithiobacillus genus, especially of A. thiooxidans and A.ferrooxidans species are considered as very aggressive biological factors that influences deterioration of many materials, including mineral building materials like concrete and stoneware. Biofilms formed by these bacteria play a significant role in microbiologically influenced corrosion (MIC) of various materials in conditions that ensure sufficient moisture. The aim of this work was to assess differences between A. thiooxidans and A. ferrooxidans biofilms formed on concrete and stoneware. Both strains were prone to form biofilms on concrete and stoneware. However, the type of mineral materials strongly influenced metabolic activities of the tested strains, thus providing to formation of biofilms displaying different features. The higher activities of cells were observed in biofilms of A.ferrooxidans bacteria. The higher total biomass attached to the material surface as well as concentration of proteins in liquid culture medium were observed in biofilms grown on concrete samples. The optimal time of biofilm growth on tested materials was 48 hours on concrete, and 72 hours on stoneware. Amongst materials tested, concrete samples were more susceptible to corrosion in the presence of A. thiooxidans and A. ferrooxidans bacteria.
Microbiologically Induced Corrosion Monitoring Using Open-Circuit Potential (OCP) Measurements
Authors: Mohd Rasol Rosilawati , Abu Bakar Akrima , Noor Norhazilan Md , Yahaya Nordin , Ismail Mardhiah
Published: January 2015

This study investigates how sulfate-reducing bacteria (SRB) influence the process of microbiologically induced corrosion (MIC) of carbon steel by measuring corrosion potential using open-circuit potential (OCP) measurements. MIC is mainly influenced by Desulfovibrio vulgaris, formerly known as Desulfovibrio desulfuricans subsp. Desulfuricans, deposited as spirillum desulfuricans, which produces D(-)-lactate dehydrogenase. This strain was recommended by ATCC to be used in the tests described in ASTM. A pure colony of SRB was isolated from the Baram and Sungai Ular areas in Malaysia. An evaluation of SRB growth was performed during the test in the inoculated medium anaerobically at 37 ̊. The results showed that the corrosion potential Eoc increases in the presence of SRB in pure and mixed cultures as compared to the control sample. These results indicate that the SRB caused the metal loss on the carbon steel surface through direct corrosive action of the H2S generated by the bacteria during their metabolic process of reducing sulfates to the sulfide form.
Turbidity Method to Measure the Growth of Anaerobic Bacteria Related to Microbiologically Influenced Corrosion
Authors: Abu Bakar Akrima , Mohd Rasol Rosilawati , Yahaya Nordin , Noor Norhazilan Md , bin Mohd Ali Muhammad Khairool Fahmy
Published: January 2015

This study defines the interrelationship between turbidities and cell number counting efficiency for the growth of one of the microbiologically influenced corrosion (MIC) species in a medium. The metabolism activities during bacteria growth can accelerate the corrosion process and shorten the reliability of pipelines. Thus, the investigation of MIC species’ development and metabolic activities is significant. An experiment was performed on sulfate-reducing bacteria (SRB) that practiced the medium as the substance to grow. Desulfovibrio vulgaris, a strain of SRB, was cultured in a postgate C medium to measure the bacteria survival using two different measurement methods. The medium was modified to pH 7.5 at 37°C and placed in anaerobic vials. During 24 hours of incubation, samples were retrieved, and the value of turbidity and cell numbers was measured. Based on the SRB growth graph pattern, the amount of bacteria cell numbers was increased parallel to the value of the medium’s turbidity in respect to time. Both values (turbidity and bacteria cell numbers) dramatically increased from hour1 to hour24. The results supported that the turbidity value was positively correlated with bacteria cell numbers.
Novel Concepts on the Growth of Corrosion Fatigue Small and Short Cracks
Authors: Lukaszewicz Mikolaj , Zhou Shen Gi , Turnbull Alan
Published: January 2015

Corrosion fatigue small, short and long crack growth rates have been determined for a 12Cr steam turbine steel in aerated 300 ppb Cl- + 300 ppb SO42- solution and in air at 90 °C. The crack growth rate for short and long cracks was monitored by direct current potential drop (DCPD) and for the small cracks by combining high resolution optical microscopy and DCPD. Comparison of the fatigue growth rate demonstrated that in solution the short crack growth rate was remarkably enhanced in comparison to long cracks, when the crack size is smaller than 250 μm. This enhancement was attributed to the electrochemical crack size effect associated with greater anodic polarisation of the short crack in such low conductivity solution. However, such enhanced growth was not observed for small cracks, which was rationalised on the basis of additional contribution of current from the pit limiting crack-tip polarisation.