Search results

1 – 10 of 412
To view the access options for this content please click here
Article
Publication date: 4 January 2016

M.Y. Zhang, L.Z. Liu, L. Weng, W.W. Cui and K.S. Hui

– The aim of this study was to fabricate polyimide (PI)/Al2O3 composite films via surface modification and ion exchange techniques, and examine their properties.

Abstract

Purpose

The aim of this study was to fabricate polyimide (PI)/Al2O3 composite films via surface modification and ion exchange techniques, and examine their properties.

Design/methodology/approach

The method involves hydrolyzing the PI film double surface layers in an aqueous potassium hydroxide (KOH) solution and incorporating aluminium ions (Al3+) into the hydrolyzed layers of the PI film via subsequent ion exchange, followed by a treatment of the Al3+-loaded PI films with an aqueous ammonia solution, which leads to the formation of Al(OH)3 in the surface-modified layers. After a final thermal annealing treatment in ambient air, the Al(OH)3 decomposes to Al2O3, and forms composite layers on both surfaces of the re-imidized PI film.

Findings

The PI/Al2O3 composite film obtained with a 6 hours of KOH treatment exhibited excellent thermal stability, good mechanical properties and better electric breakdown strength and corona-resistance properties than the pristine PI film.

Practical implications

The method for obtaining the composite films in this paper is worth consideration, but additional research will be needed. Furthermore, this method is of general importance for the fabrication of composite PI films with tailored properties.

Originality/value

This study showed that surface modification and ion-exchange techniques are powerful methodologies for the fabrication of PI/Al2O3 composite films.

Details

Pigment & Resin Technology, vol. 45 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 17 May 2013

Nivin M. Ahmed, Hassan S. Emira and Hesham M. Tawfik

Ion‐exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion‐exchange

Abstract

Purpose

Ion‐exchange clays containing sodium such as bentonite and montmorillonite have the ability to exchange their cations. Few studies conducted with this type of ion‐exchange pigments are not conclusive about their anticorrosive efficiency. The present research aims to address the study on the anticorrosive efficiency of this type of pigments in chlorinated rubber paints. Sodium‐bentonite was exchanged with Zn, Sr and Zn‐Sr to be applied on low carbon steel specimens and study the anticorrosive performances of these new ion‐exchanged bentonites (IEBs) in anticorrosive paint formulations.

Design/methodology/approach

The new pigments were characterised using scanning electron microscopy (SEM) and X‐ray fluorescence (XRF) to determine the CEC (cation exchange capacity) of the different exchanged cations. Evaluation of the ion‐exchanged and Na‐bentonite pigments using international standard testing methods (ASTM) was estimated. Paint systems manufactured with these ion‐exchange pigments have been subjected to adhesion, accelerated corrosion laboratory tests, and EIS in order to assess their anticorrosive behaviour.

Findings

The results of this work revealed that the ion‐exchange bentonite (IEBs) pigments showed high anticorrosive performance that can be arranged as follows: Sr‐bentonite was better than Zn‐Bentonite and both were better than the double Zn‐Sr‐bentonite indicating an antagonism behaviour between the two cations when present together.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers.

Originality/value

These prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings.

Details

Pigment & Resin Technology, vol. 42 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 1 October 1974

W.U. Malik and Laxman Aggarwal

Mayne and coworkers have carried out intensive studies on the electro‐chemical behaviour of anti‐corrosive paint systems. More recently they have shown that the paint…

Abstract

Mayne and coworkers have carried out intensive studies on the electro‐chemical behaviour of anti‐corrosive paint systems. More recently they have shown that the paint films possess ionogenic sites which become ionised by the absorption of water or moisture and thus become selectively permeable to ions and the process of ion exchange follows. They have also studied the variations in the electrical resistance of a soya alkyd film as a function of the uptake of metallic ions. Bacon et. al. used electrical resistance measurements in assessing the anti‐corrosive properties of some three hundred paint systems, using mild steel panels coated with pigmented paint media as one of the electrodes of the test cell and have shown that the method is quite suitable for predicting their actual performances in marine environments. Khullar and Ulfvarson have determined the ion exchange capacities and ion exchange rates of about twenty different paint media films and drawn a sort of relation between their ionic behaviour and anti‐corrosive abilities.

Details

Pigment & Resin Technology, vol. 3 no. 10
Type: Research Article
ISSN: 0369-9420

To view the access options for this content please click here
Article
Publication date: 22 March 2011

Nivin M. Ahmed, Hassan S. Emira and Mohamed M. Selim

Organic coatings remain the most widely used way of protecting steel structures from corrosion. Traditional anticorrosive paints contain lead or hexavalent chromium…

Abstract

Purpose

Organic coatings remain the most widely used way of protecting steel structures from corrosion. Traditional anticorrosive paints contain lead or hexavalent chromium compounds as active pigments. The use of these classical chromates is nowadays restricted by increasing environmental awareness and stringent national and international regulations. An alternative is the use of ion‐exchangeable pigments. The purpose of this paper is to show that cation‐exchanged zeolites can be considered as a safe and efficient alternative to traditional hazardous pigments in protecting steel surfaces.

Design/methodology/approach

The new pigments were characterised using different analytical and spectro‐photometric techniques. Characterisation of these pigments using X‐ray diffraction and scanning electron microscopy were done. X‐ray fluorescence was employed to elucidate the concentration of different elements in the prepared pigments. Evaluation of the ion‐exchanged and initial zeolite pigments using international standard testing methods (ASTM) was estimated. Testing the anticorrosive protection of cation‐exchanged zeolites in alkyd paints formulated based on their pigment volume concentration/critical pigment volume concentration was studied, and then these new pigments were applied on cold‐rolled steel panels. The physico‐mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5 per cent NaCl for 28 days were tested.

Findings

The results of this work revealed that paint films containing initial Na‐zeolite performed the least protection behaviour, while films including Zn, Ca and Mg‐zeolites were better in their corrosion protection performance, and they can be arranged as Zn‐zeolite>Ca‐zeolite>Mg‐zeolite.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers.

Originality/value

The paper shows that these prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings.

Details

Pigment & Resin Technology, vol. 40 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 1976

Wahid U. Malik and L.K. Aggarwal

Introduction The changes in electrical resistance of paint films immersed in an electroplyte has long been associated with anti‐corrosive paints. As early as 1913, Digby…

Abstract

Introduction The changes in electrical resistance of paint films immersed in an electroplyte has long been associated with anti‐corrosive paints. As early as 1913, Digby and Paterson used painted steel panels in galvanic cells and measured the e.m.f.'s of the cells at different intervals. These studies were extended by Bacon et.al.. They have shown that changes in electrical resistance measurements have good relation with anto‐corrosive paints which are to be used under water.

Details

Anti-Corrosion Methods and Materials, vol. 23 no. 6
Type: Research Article
ISSN: 0003-5599

To view the access options for this content please click here
Article
Publication date: 27 May 2014

Ahmad Mashal, Jehad Abu-Dahrieh, Ashraf A. Ahmed, Lukumon Oyedele, No’man Haimour, Ahmad Al-Haj-Ali and David Rooney

The purpose of this paper is to investigate the performance of natural Jordanian zeolite tuff to remove ammonia from aqueous solutions using a laboratory batch method and…

Abstract

Purpose

The purpose of this paper is to investigate the performance of natural Jordanian zeolite tuff to remove ammonia from aqueous solutions using a laboratory batch method and fixed-bed column apparatus. Equilibrium data were fitted to Langmuir and Freundlich models.

Design/methodology/approach

Column experiments were conducted in packed bed column. The used apparatus consisted of a bench-mounted glass column of 2.5 cm inside diameter and 100 cm height (column volume = 490 cm3). The column was packed with a certain amount of zeolite to give the desired bed height. The feeding solution was supplied from a 30 liter plastic container at the beginning of each experiment and fed to the column down-flow through a glass flow meter having a working range of 10-280ml/min.

Findings

Ammonium ion exchange by natural Jordanian zeolite data were fitted by Langmuir and Freundlich isotherms. Continuous sorption of ammonium ions by natural Jordanian zeolite tuff has proven to be effective in decreasing concentrations ranging from 15-50 mg NH4-N/L down to levels below 1 mg/l. Breakthrough time increased by increasing the bed depth as well as decreasing zeolite particle size, solution flow-rate, initial NH4+ concentration and pH. Sorption of ammonium by the zeolite under the tested conditions gave the sorption capacity of 28 mg NH4-N/L at 20°C, and 32 mg NH4-N/L at 30°C.

Originality/value

This research investigates the performance of natural Jordanian zeolite tuff to remove ammonia from aqueous solutions using a laboratory batch method and fixed-bed column apparatus. The equilibrium data of the sorption of Ammonia were plotted by using the Langmuir and Freundlich isotherms, then the experimental data were compared to the predictions of the above equilibrium isotherm models. It is clear that the NH4+ ion exchange data fitted better with Langmuir isotherm than with Freundlich model and gave an adequate correlation coefficient value.

Details

World Journal of Science, Technology and Sustainable Development, vol. 11 no. 2
Type: Research Article
ISSN: 2042-5945

Keywords

To view the access options for this content please click here
Article
Publication date: 1 January 2006

Eniko T. Enikov and Geon S. Seo

This paper describes the development and the numerical analysis of an electrochemical model for the analysis of a novel polymer/metal composite actuator. A general…

Abstract

This paper describes the development and the numerical analysis of an electrochemical model for the analysis of a novel polymer/metal composite actuator. A general continuum model describing the transport and deformation processes of these actuators is briefly presented, along with a detailed description of the simulation scheme used to predict deformation, current, and mass transport. The predictions of the model are compared with experimental data, indicating a significant role of water transport in the large‐scale deformation. Comparison of the simulations and experimental data showed good agreement confirming the central role of water transport in the deformation process. For the sake of completeness the fabrication process and testing apparatus are also described.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

To view the access options for this content please click here
Article
Publication date: 7 August 2017

Zbigniew Magonski and Barbara Dziurdzia

The aim of this paper is to find the electrical representation of a solid oxide fuel cell (SOFC) that enables the application of typical exploitation characteristics of…

Abstract

Purpose

The aim of this paper is to find the electrical representation of a solid oxide fuel cell (SOFC) that enables the application of typical exploitation characteristics of fuel cells for estimation of fuel cell parameters (for example, exchange current) and easy analysis of phenomena occurred during the fuel cell operation.

Design/methodology/approach

Three-layer structure of an SOFC, where a thin semi-conducting layer of electrolyte separates the anode from the cathode, shows a strong similarity to typical semiconductor devices built on the basis of P-N junctions, like diodes or transistors. Current–voltage (I-V) characteristics of a fuel cell can be described by the same mathematical functions as I-V plots of semiconductor devices. On the basis of this similarity and analysis of impedance spectra of a real fuel cell, two electrical representations of the SOFC have been created.

Findings

The simplified electrical representation of SOFC consists of a voltage source connected in series with a diode, which symbolizes a voltage drop on a cell cathode, and two resistors. This model is based on the similarity of Butler-Volmer to Shockley equation. The advanced representation comprises a voltage source connected in series with a bipolar transistor in close to saturation mode and two resistors. The base-emitter junction of the transistor represents voltage drop on the cell cathode, and the base-collector junction represents voltage drop on the cell anode. This model is based on the similarity of Butler-Volmer equation to Ebers-Moll equation.

Originality/value

The proposed approach based on the Shockley and Ebers-Moll formulas enables the more accurate estimation of the ion exchange current and other fuel cell parameters than the approach based on the Butler-Volmer and Tafel formulas. The usability of semiconductor models for analysis of SOFC operation was proved. The models were successively applied in a new design of a planar ceramic fuel cell, which features by reduced thermal capacity, short start-up time and limited number of metal components and which has become the basis for the SOFC stack design.

Details

Microelectronics International, vol. 34 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

To view the access options for this content please click here
Article
Publication date: 12 June 2017

Xiang Nie, Shanshan Zhao and Yanheng Li

This paper aims to take the four resin as adsorbent and coal ash alkaline solution as the material and use the single factor experimental method to study absorption…

Abstract

Purpose

This paper aims to take the four resin as adsorbent and coal ash alkaline solution as the material and use the single factor experimental method to study absorption influence factors for each resin to absorb lithium. At the same time, the authors got the special properties of some kinds of resin and compared the test results of each resin at the optimum factors.

Design/methodology/approach

Because many factors affect the test, this study uses the method of comparison and control variables. This method study on the influencing factors of ion exchange resin adsorption Li+.

Findings

In these adsorption experiments, the basic resin adsorption effect is more obvious. The optimum adsorption conditions are as follows: resin quality is 0.1 g, the volume of fly ash solution is 100 ml, magnetic stirrer speed is 140 r/min and the adsorption time is 60 min. Under these conditions, the adsorption rate of Li+ could reach 25.17 per cent aluminum.

Originality/value

Li extracted from coal ash can not only relieve the lithium resources in short supply but can also provide a new mode to the field of coal resources in recycling economy and transition economy. At the same time, the extraction of Li resources will provide an important reserve of raw materials for the future of nuclear power plant.

Details

World Journal of Engineering, vol. 14 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Content available
Article
Publication date: 1 June 1998

Abstract

Details

Anti-Corrosion Methods and Materials, vol. 45 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

1 – 10 of 412