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1 – 10 of 554
Article
Publication date: 23 May 2008

S.A. Umoren and E.E. Ebenso

The purpose of this paper is to investigate the effect of Raphia hookeri exudate gum and halide ions on the corrosion inhibition of aluminium in HCl solutions at 30‐60°C…

Abstract

Purpose

The purpose of this paper is to investigate the effect of Raphia hookeri exudate gum and halide ions on the corrosion inhibition of aluminium in HCl solutions at 30‐60°C and to study the mechanism of action.

Design/methodology/approach

The corrosion rates were determined using the gravimetric (weight loss), gasometric (hydrogen evolution) and thermometric techniques. The results obtained in the absence and presence of Raphia hookeri, halides and Raphia hookerihalides combination were used to calculate the inhibition efficiency (%I), degree of surface coverage and to propose the mechanism of inhibition and type of adsorption.

Findings

Results obtained showed that the Raphia hookeri exudates gum acted as an inhibitor for aluminium corrosion in acidic environment. Inhibition efficiency (%I) increased with increase in concentration of the Raphia hookeri exudates gum and synergistically increased to a considerable extent on the addition of halide ions. The increase in inhibition efficiency (%I) and surface coverage (θ) in the presence of the halides was found to be in the order I > Br > Cl which indicates that the radii as well as electronegativity of the halide ions play a significant role in the adsorption process. Raphia hookeri exudates gum obeys Freundlich, Langmuir and Temkin adsorption isotherms. Phenomenon of physical adsorption is proposed from the values of kinetic/thermodynamic parameters obtained. The values of synergism parameter (SI) obtained for the halides are greater than unity suggesting that the enhanced inhibition efficiency of the Raphia hookeri caused by the addition of the halide ions is only due to synergistic effect.

Research limitations/implications

Electrochemical studies such as polarization and AC impedance spectra will throw more light on the mechanistic aspects of the corrosion inhibition and more exudate gums need to be evaluated as corrosion inhibitors.

Practical implications

Raphia hookeri exudate gum can be used as corrosion inhibitor and the addition of halides to it improves the inhibition efficiency considerably.

Originality/value

This paper provides new information on the use of exudate gums as corrosion inhibitors and addition of halides in acidic medium. This environmentally friendly inhibitor could find possible applications in metal surface anodizing and surface coatings.

Details

Pigment & Resin Technology, vol. 37 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 September 2006

S.A. Umoren, O. Ogbobe, E.E. Ebenso and U.J. Ekpe

To investigate the effect of halide ions on the corrosion inhibition of mild steel using polyvinyl alcohol (PVA) in H2SO4 at 30‐60°C and to study the mechanism of action.

Abstract

Purpose

To investigate the effect of halide ions on the corrosion inhibition of mild steel using polyvinyl alcohol (PVA) in H2SO4 at 30‐60°C and to study the mechanism of action.

Design/methodology/approach

The corrosion rates were determined using the gravimetric (weight loss) and gasometric (hydrogen evolution) techniques. The results obtained in the absence and presence of PVA, halides, PVA – halides combination were used to calculate the inhibition efficiency (%I), degree of surface coverage and to propose the mechanism of inhibition and type of adsorption.

Findings

Results obtained showed that inhibition efficiency (%I) increased with the increase in concentration of PVA, on the addition of halides and with the increase in temperature. Phenomenon of chemical adsorption was proposed and PVA was found to obey Langmuir, Flory‐Huggins and Freundlich adsorption isotherms. The synergism parameter, S1, evaluated was found to be greater than unity and the values of Ea, ΔH°, ΔS° and ΔG° obtained revealed that the adsorption process was spontaneous.

Research limitations/implications

Electrochemical studies such as polarization and AC impedance spectra will enlighten more on the mechanistic aspects of the corrosion inhibition and more polymers need to be evaluated as corrosion inhibitors.

Practical implications

PVA can be used as corrosion inhibitor and the addition of halides to PVA improves the inhibition efficiency considerably.

Originality/value

This paper provides new information on the effects of halides on the corrosion inhibition using PVA as an inhibitor for mild steel in acidic medium. Such a study had not been reported elsewhere.

Details

Pigment & Resin Technology, vol. 35 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 1 October 2005

E.E. Oguzie, G.N. Onuoha and A.I. Onuchukwu

To investigate the inhibitive effect of Congo red dye (CR) for aluminium corrosion in strong alkaline solutions and evaluate the synergistic effect of halide ions on the…

Abstract

Purpose

To investigate the inhibitive effect of Congo red dye (CR) for aluminium corrosion in strong alkaline solutions and evaluate the synergistic effect of halide ions on the inhibition efficiency.

Design/methodology/approach

Corrosion rates of aluminium test coupons were determined by gravimetric technique at 30 and 60°C. Inhibition efficiencies of the additives (0.01‐5.0 mM CR and 5.0 mM CR+0.5 mM halides) were evaluated by comparing corrosion rates of the test coupons in 2 M KOH solution in the absence and presence of the additives.

Findings

CR inhibited aluminium corrosion in 2 M KOH by physical adsorption of the dye molecules on the corroding metal surface. Maximum efficiency at 30 and 60°C was 31.72 and 19.32 per cent, respectively. Dye adsorption was enhanced in the presence of halides in the order KCl < KBr < KI, with KI increasing efficiency up to 48.63 and 41.70 per cent at 30 and 60°C, respectively.

Research limitations/implications

Further studies to involve variation of dye and halide concentrations for CR+halide systems to determine the best combination for optimum inhibition synergism.

Originality/value

This paper forms part of an extensive database on the inhibition characteristics of organic dyes for corrosion of different metals in various aggressive environments. This is to serve as a guide to possible applications in metal‐surface anodizing and as additives in surface coatings for service in different environments.

Details

Anti-Corrosion Methods and Materials, vol. 52 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 27 June 2008

A. Yurt and Y. Mihrican

The purpose of this paper is to investigate the inhibition effect of 2‐aminoethane thiol hydrochloride, 2‐cystamine dihydrochloride, 2,3‐dimercapto‐1‐propanol…

Abstract

Purpose

The purpose of this paper is to investigate the inhibition effect of 2‐aminoethane thiol hydrochloride, 2‐cystamine dihydrochloride, 2,3‐dimercapto‐1‐propanol, 1,2‐ethanedithiol, and the synergistic effect of these compounds with halide ions (Cl, Br, I) and with some metal cations (Co2 + , Ni2 + , Cu2 + , Zn2 + ).

Design/methodology/approach

The inhibiting effect of the studied thiols on the corrosion of carbon steel in 0.5 M H2SO4 solution were investigated using potentiodynamic polarisation, electrochemical impedance spectroscopy and linear polarisation methods.

Findings

The inhibition action of thiols depends mainly on the type of the heteroatom present in the inhibitor molecule. The increase in inhibition efficiencies with increase in inhibitor concentration revealed that the studied compounds were adsorbed onto steel surfaces and the adsorption mechanism obeyed the Langmuir adsorption isotherm. Polarisation curves indicated that thiols containing both N and S atoms in their structure behaved as mixed type inhibitors, while thiols containing only an S atom in their structure acted essentially as anodic inhibitors. The increase in the inhibition efficiencies of thiols with the addition of halide ions indicates that halides play important role in the adsorption process. The synergistic effect of the studied metal cations could be explained by the adsorption of complex ions formed from thiol molecules and metal cations.

Originality/value

This paper provides useful information about the relationship between inhibition efficiencies and the structures of thiols and clarifies the mechanism of the synergistic effects of some halides and some metal cations.

Details

Anti-Corrosion Methods and Materials, vol. 55 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 January 2006

E.E. Oguzie and E.E. Ebenso

To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide

Abstract

Purpose

To investigate the efficacy of Congo red dye (CR) as an inhibitor of the acid corrosion of mild steel and aluminium alloy (AA 1060) and to assess the influence of halide ions on the inhibition efficiency.

Design/methodology/approach

Corrosion rates were estimated by monitoring the weight losses of the metal specimen as a function of time at different temperatures. Inhibition efficiency was determined by comparing the corrosion rates in the acid medium in the absence and presence of the additive.

Findings

CR dye reduced the corrosion rates of mild steel and aluminium in the acidic environment. Better inhibition was observed with the mild steel specimen. Protection efficiency was sensitive to inhibitor concentration as well as temperature and generally increased with an increase in CR dye concentration. The halide additives improved the inhibition efficiency in the order KCl < KBr < KI.

Research limitations/implications

The inhibiting effect of CR dye was studied within a fixed concentration range, which could be expanded for further studies. The same applies to the CR+halide systems. Also, the dye structure could be modified by introducing different functional groups, and the effect on inhibition efficiency investigated.

Practical implications

The research findings could find practical application in corrosion control in aqueous acidic environments.

Originality/value

This paper provides new information on the inhibiting characteristics of CR dye under the specified conditions, as a guide to possible applications in metal surface anodizing and surface coatings.

Details

Pigment & Resin Technology, vol. 35 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 5 September 2016

Kanlaya Phaphon, Sumrit Wacharasindhu and Amorn Petsom

This study aims to synthesize polyethylene glycol (PEG)-rosin derivatives from rosin and PEG for the production of solid soldering fluxes. The PEG-rosin derivatives would…

Abstract

Purpose

This study aims to synthesize polyethylene glycol (PEG)-rosin derivatives from rosin and PEG for the production of solid soldering fluxes. The PEG-rosin derivatives would be water soluble, and the resulting solid soldering fluxes would have reasonable wetting ability when combined with a low-halide-content activator.

Design/methodology/approach

This paper presents a synthetic process for PEG-rosin derivatives. The reaction conditions (including catalyst type, catalyst concentration, reaction temperature and PEG type) were optimized for the synthesis of PEG-rosin derivatives. The chemical and physical properties of PEG-rosin derivatives were characterized by Fourier transform infrared spectroscopy, carbon-13 nuclear magnetic resonance spectrometry, differential scanning calorimetry and gel permeation chromatography. The production and characteristics of water-soluble rosin fluxes (WSRFs) were studied according to the standards of the Japanese Industrial Standards (JIS) Committees.

Findings

WSRs were successfully synthesized from rosin and PEG using 2 per cent ZnO as a catalyst, with a 2:1 molar ratio of rosin:PEG at 250°C over 9 h. The resulting WSRs were completely soluble in water. As the PEG3000-rosin had the highest melting point (55.2°C), it was chosen for the preparation of the WSRFs. Activators such as succinic acid, glutaric acid, ethylamine hydrochloride and diethylamine hydrobromide were selected for use in the production of the fluxes. It was found that WSRF 09 and WSRF 04 gave the best performance with the lead-free Sn-0.7Cu solder alloy in terms of good solderability, low halide content (less than 1,500 ppm), high insulation resistance and low corrosion. These fluxes were applied to produce solder pastes with Sn-3.0Ag-0.5Cu alloy and they passed the performance tests as expected for solder paste.

Research limitations/implications

Further studies are necessary on large-scale production and to compare the performance of these fluxes to those from conventional water-soluble fluxes currently available in the market. Application of these fluxes on low-temperature solder alloys such as SnZn and SnBi (Ren et al., 2016) worth further study.

Originality/value

The classification of flux systems according to the JIS 3283 standard does not specify PEG-rosin derivatives in the flux; nevertheless, ranking of the flux systems based on the halide content and corrosion properties of activators would be useful information when selecting flux systems for electronics soldering in water-washable applications. The application of these fluxes in solder paste gave very promising results and is worth investigating into more detail, as well as field test.

Details

Soldering & Surface Mount Technology, vol. 28 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 1 January 1995

H. Abbas and A.A. Khedr

Introduction The passivation of iron in aqueous media has been investigated over a number of years. Bartlett and Stephenson and Froment et al. have given a deep insight…

Abstract

Introduction The passivation of iron in aqueous media has been investigated over a number of years. Bartlett and Stephenson and Froment et al. have given a deep insight into the processes of anodic depositon of FeSO4 on iron in H2SO4 solutions. Krstulonic et al. investigated the anodic passivation of Armco iron in a wide range of concentrations of suphuric avid. Alloy elements (Cr, Ni, Mo) are sometimes added to carbon steels to improve their mechanical properties and/or the effects of heat treatment. These metals can increase or decrease corrision resistance depending on the harshness of the environment. The most important alloy of stainless steel is chromium, which induces the formation of a good protective oxide film. According to the literature the alloy must contain at least 1.3 per cent chromium to form a stable passive film. The influence of chromium on the anodic dissolution of Fe‐Cr in sulphuric acid solutions has been the object of several investigations.

Details

Anti-Corrosion Methods and Materials, vol. 42 no. 1
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 1 December 2005

E.E. Oguzie

To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H2SO4 solutions, respectively, and to assess the…

Abstract

Purpose

To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H2SO4 solutions, respectively, and to assess the effect of temperature and halide additives on the inhibition efficiency.

Design/methodology/approach

Corrosion rate was monitored by careful volumetric measurement of the evolved hydrogen gas at fixed time intervals. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of additive. Attempts were made to elucidate the inhibition mechanism from the trend of inhibition efficiency with temperature. The adsorption mode of inhibiting species in the extract was assessed by considering the influence of both acid and halide ions on inhibition efficiency.

Findings

Telfaria occidentalis extract inhibited mild steel corrosion in 2 M HCl and 1 M H2SO4 solutions. Inhibition efficiency increased with extract concentration but decreased with rise in temperature. Synergistic effects increased the efficiency of the extract in the presence of halide additives in the order KCl<KBr<KI. Protonated species in the extract composition played a vital role in the inhibiting action.

Originality/value

This paper provides new information on the inhibiting characteristics of Telfaria occidentalis extract under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodising and surface coatings.

Details

Pigment & Resin Technology, vol. 34 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 18 September 2017

Abbas Khammas Hussein

The purpose of this paper is to obtain a single setting (optimal setting) of various input parameters of pack cementation process, i.e. halide salt activator, powder of…

Abstract

Purpose

The purpose of this paper is to obtain a single setting (optimal setting) of various input parameters of pack cementation process, i.e. halide salt activator, powder of master alloy and wt% of Y2O3 to obtain a single output characteristic as a whole namely resistance of hot corrosion for T91 steel.

Design/methodology/approach

The multi-criterion methodology based on Taguchi approach and utility concept has been used for optimization of the multiple performance characteristics namely hot corrosion rate KP1, KP2 and KP3 for pack cementation coated T91 steel in chlorine and vanadium environment.

Findings

All the three pack cementation parameters, namely, halide salt activator, powder of master alloy and wt% of Y2O3 had a significant effect on the utility function based on analysis of variance for multiple performances. The percentage contribution of halide activator (1.54 percent), master alloy powder (4.66 percent) and wt% Y2O3 (93.79 percent). The results indicated the beneficial influence of yttrium on the chemical stability of the protective layer in presence of chlorine and vanadium environments. The optimal parameter settings obtained in this study is A2B2C1, i.e. halide salt activator (NaCl), powder of master alloy (92Cr-8Al) and 1wt% of Y2O3.

Research limitations/implications

The outcome of this study shall be useful to explore the possible use of the developed coating for high temperature components. Unfortunately, the pack cementation was normally limited by the diffusion and reaction kinetics involved, which has a detrimental effect on the mechanical properties of work pieces. Therefore, reducing pack cementation temperature is required for widespread application of the pack coatings.

Social implications

Pack coating at optimum conditions can be used for surface coating technologies to economically improve high temperature oxidation, corrosion resistance of components.

Originality/value

The multi-criterion methodology based on Taguchi approach and utility concept has been used for first time for parametric optimization of wt% Y2O3 modified chromium- aluminide coatings for T91 steel.

Details

Multidiscipline Modeling in Materials and Structures, vol. 13 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 25 April 2008

Rolando Quintana, Mark T. Leung and An‐Sing Chen

The purpose of this paper is to identify, study and quantify the effects of lighting on yield and productivity in manual electronics assembly (MEA) and inspection as a…

1027

Abstract

Purpose

The purpose of this paper is to identify, study and quantify the effects of lighting on yield and productivity in manual electronics assembly (MEA) and inspection as a limiting work design criterion. The study also examines the potential interactions among lighting option, workers' age, and years of experience.

Design/methodology/approach

A three‐factor full factorial experiment is adopted to statistically evaluate the independent variables (process yield and assembly time) versus randomly selected levels of three factors: type of light (low pressure sodium, mercury vapor lamps, and metal halide lamps measured in foot‐candle luminaries), operator age, and years on the job. A residual analysis is also conducted to complement and corroborate the ANOVA findings.

Findings

The study finds that metal halide lamps, based on the ANSI recommended ranges of 186‐464 foot‐candles, lead to significant increases in labor productivity and through‐put, irrespective of operators' age and years of experience. Although these lamps have a significantly shorter life span than that of low‐pressure sodium and mercury vapor lamps, the realized benefits far exceed the incremental cost of illumination devices. The results indicate that a modest capital investment is able to generate solid improvements in yield and processing time in a typical MEA environment.

Originality/value

The relations between productivity and lighting intensity and type have never been studied in the area of MEA. This empirical study uncovers the effects through a systematic experimentation of this essential relationship in a typical MEA environment. The findings, which can be generalized to other facilities, are validated by an array of statistical procedures and proved to be significant. The paper contributes useful knowledge to the fields of engineering management and facility design.

Details

International Journal of Productivity and Performance Management, vol. 57 no. 4
Type: Research Article
ISSN: 1741-0401

Keywords

1 – 10 of 554