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Article
Publication date: 1 January 1993

R.J. Chester, G. Clark, B.R.W. Hinton and A.A. Baker

OVER several decades the Defence Science and Technology Organisation's Aeronautical Research Laboratory (ARL) has undertaken materials research focussed on support for maintenance…

101

Abstract

OVER several decades the Defence Science and Technology Organisation's Aeronautical Research Laboratory (ARL) has undertaken materials research focussed on support for maintenance and life extension of military aircraft. The reason for selecting this research focus — rather than development of new materials — derives from the fact that approximately half of the through‐life cost of a military aircraft is spent on maintenance. The cost‐effectiveness of research which reduces maintenance costs can therefore be substantial. Similarly, research activities which prolong the service life of an aircraft can provide large benefits by delaying purchase of a replacement fleet; acquisition costs are also large, at approximately one‐third of the through‐life cost of an aircraft fleet. A recent Australian evaluation of the cost‐effectiveness of materials‐related research aimed at reducing cost‐of ownership reported a benefit: cost ratio of the order of 25:1. One example is the Mirage IIIO whose initial design safe life of 24000 flying hours was extended to 4,000 flying hours as a result of research and development carried out at ARL; the aircraft was flown for six years more than initially planned, effectively delaying the need to replace the fleet. This type of life extension R&D requires a range of scientific and engineering approaches, focussed on evaluation of potential problems, and the development of technologically feasible life‐extension measures. Many of the maintenance‐reducing and life‐extension developments for military aircraft are readily applicable to aging civil aircraft. This paper highlights some of the materials research — specifically improved corrosion protection, evaluation of defects using non‐destructive inspection and repair of damage — which is now proving to be applicable to aging aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 65 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 March 1993

R.J. Chester, G. Clark, B.R.W. Hinton and A.A. Baker

Bonded composite repair technology was pioneered at ARL and has been successfully used to repair a wide range of military and civilian aircraft. The technique has proved to be…

71

Abstract

Bonded composite repair technology was pioneered at ARL and has been successfully used to repair a wide range of military and civilian aircraft. The technique has proved to be very cost effective and has been shown to increase the availability of aircraft by significantly reducing the repair time. ARL has undertaken collaborative work with a number of airline operators, the CAA and FAA and with Boeing to demonstrate the advantage of the technology when compared to conventional repair methods. The Defence Science and Technology Organisation (DSTO) has signed a licence agreement with an Australian company. Helitech P/L, to exploit this technology on a world‐wide basis.

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Aircraft Engineering and Aerospace Technology, vol. 65 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 23 May 2008

A. Amadeh, S.R. Allahkaram, S.R. Hosseini, H. Moradi and A. Abdolhosseini

Application of rare earth (RE) salts as a corrosion inhibitor was first proposed by Goldie and McCarrol in 1984. They showed that, with the addition of 0.001 M of Ce(NO3) or La(NO3

600

Abstract

Purpose

Application of rare earth (RE) salts as a corrosion inhibitor was first proposed by Goldie and McCarrol in 1984. They showed that, with the addition of 0.001 M of Ce(NO3) or La(NO3) to 3.5% NaCl solution, the inhibition efficiencies were 91 and 82% for carbon steel, respectively. The aim of this paper is to study the inhibition of a mixture of Ce and La cations on the corrosion prevention of St37 carbon steel in aerated NaCl solutions using weight loss, potentiodynamic polarization, open circuit potential and constant potential measurements.

Design/methodology/approach

In this study, St37 steel was used as an experimental sample. The applied inhibitor was a powder mixture of Ce and La oxides with the ratio of Ce/La = 2/1. Each gram of this powder was dissolved in 4 cc acetic acid because of their insolubility in water. Steel samples were polished with 120 to 800 grit SiC polishing papers, deoxidized in 15 per cent HCl, and then ultrasonically cleaned in ethanol. They were degreased in acetone and were dried in a flow of hot air.

Findings

It has been shown that a mixture of RE cations (Ce and La) can be used as a corrosion inhibitor for carbon steel in NaCl containing solutions. The optimum inhibitor concentration was found to be 500 ppm with a maximum inhibition efficiency of 76%. An increase in Cl ion concentration and a rise in temperature from room temperature to 70°C can have an adverse effect on corrosion inhibition efficiency.

Originality/value

The results obtained from various experiments indicated that the mixture of Ce and La cations could be considered as a suitable inhibitor for carbon steel in low to medium chloride‐containing solutions. Owing to their non‐toxic nature, they may be suitable to use in potable water pipelines.

Details

Anti-Corrosion Methods and Materials, vol. 55 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 February 1993

R.J. Chester, G. Clark, B.R.W. Hinton and A.A. Baker

Non‐destructive inspection. Safety‐by‐inspection There are several possible approaches to the safe extension of the useful service life of aging aircraft beyond the planned…

54

Abstract

Non‐destructive inspection. Safety‐by‐inspection There are several possible approaches to the safe extension of the useful service life of aging aircraft beyond the planned service life, including:

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Aircraft Engineering and Aerospace Technology, vol. 65 no. 2
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 9 September 2021

Lin Chen, Huisheng Yang, Yanjing Su and Lijie Qiao

The purpose of this study is to develop the existence and mechanism of stress corrosion cracking (SCC) for A517 steel in marine environments.

226

Abstract

Purpose

The purpose of this study is to develop the existence and mechanism of stress corrosion cracking (SCC) for A517 steel in marine environments.

Design/methodology/approach

Slow strain rate test (SSRT) and constant load tests were used to investigate the SCC susceptibility of A517 steel. In addition, the additive stresses caused by the corrosion film and hydrogen entering into steel were applied to reveal the fundamental mechanism of the SCC.

Findings

The SCC susceptibility increased due to anodic dissolution and additive stress caused by the corrosion-produced film under anode polarization. Furthermore, the SCC susceptibility increased with increasing cathodic polarization, which is due to the increased additional stress caused by hydrogen entering into the steel. However, when the cathode polarization further increased, the additional stress remained due to the constant hydrogen content, thus the SCC susceptibility did not vary. Moreover, the SCC susceptibility of A517 steel under an alternate immersion environment (AIE) was lower than that under a full immersion environment and the steel under the AIE with 0.5 W/D had the lowest SCC susceptibility.

Originality/value

The stress corrosion behaviors of A517 in marine environments under various conditions were systematically analyzed.

Details

Anti-Corrosion Methods and Materials, vol. 68 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 26 June 2009

Da‐jing Fang, Xu‐hui Mao, Ye‐ming Zhang, Zhi‐liang Chen, Min Liu and Fu‐xing Gan

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

590

Abstract

Purpose

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Design/methodology/approach

Chemical conversion treatment using 3‐Glycidoxypropyltrimethoxysilane on zinc is investigated as an alternative treatment to chromate conversion. The surface chemistry of the silane‐treated samples is investigated with mass change measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and the salt spray tests (SST). The surface morphology of samples was studied using a scanning electron microscope.

Findings

The polarization curves, EIS and SST data are in agreement. On the surface of zinc, the silane formed a compound with the cerium, thus enhancing the adhesion and corrosion resistance of the polymer film.

Originality/value

There have been few reports on the compound effects of silanes and cerium salts in the passivation process. The mechanism of this compound effect may be due to the ability of Ce3 + ions to gain access to the interface through tiny cracks or micropores in the cross‐linking structure of GPS polymer films on zinc, and the subsequent oxidation of Ce3 + to Ce4 + by H2O2 may result in a barrier effect between the electrolyte and the metallic substrate.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 14 September 2010

Qi Zheng Li, Yu Zuo, Jing Mao Zhao, Yu Ming Tang, Xu Hui Zhao and Jin Ping Xiong

By adding a Ce salt and an Nd salt to an anodizing electrolyte, modified anodic films are obtained on aluminum surfaces. This paper aims to study the effects of rare‐earth…

350

Abstract

Purpose

By adding a Ce salt and an Nd salt to an anodizing electrolyte, modified anodic films are obtained on aluminum surfaces. This paper aims to study the effects of rare‐earth elements on the corrosion resistance of the anode film.

Design/methodology/approach

The crystalline film was studied by X‐ray diffraction. The methods of scanning electron microscope, energy dispersive X‐ray analysis, electrochemical polarization, and electrochemical impedance spectroscopy (EIS) were used to characterize the properties of the films.

Findings

After rare‐earth element modification, the pores of the porous layer were very evidently smaller, the anodic film was more compact, and the thickness and hardness of the films had increased. The corrosion resistance of the anodic films modified with rare‐earth elements clearly was improved in neutral, acidic, and basic NaCl solutions. Ce showed a better effect than Nd in increasing the corrosion resistance of the films, and the film modified with Ce+Nd showed the highest corrosion resistance. EIS analysis showed that the impedances of both the barrier layer and porous layer of the anodic films increased after modification with the rare‐earth elements, indicating that the anodizing process was affected by the presence of the rare‐earth elements.

Originality/value

The results presented in this paper offer a foundation for further research and application of rare‐earth elements in aluminum anodic oxide films.

Details

Anti-Corrosion Methods and Materials, vol. 57 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 27 May 2022

Razieh Farahati, Ali Ghaffarinejad and S. Morteza Mousavi-Khoshdel

This paper aims to investigate the corrosion inhibition ability of 4–(4-nitrophenyl) thiazol-2-amine (NPT) on the copper in 1 M HCl.

46

Abstract

Purpose

This paper aims to investigate the corrosion inhibition ability of 4–(4-nitrophenyl) thiazol-2-amine (NPT) on the copper in 1 M HCl.

Design/methodology/approach

The corrosion inhibitory ability of NPT on the copper in 1 M HCl was studied by electrochemical impedance spectroscopy, scanning electron microscopy and atomic force microscopy. Theoretical calculations (molecular dynamics simulation, density functional theory and the nucleus independent chemical shift [NICS] as aromaticity indicator of the molecule) were also performed.

Findings

The corrosion inhibition efficacy of this compound was about 80%. Nyquist plots display a small arc contributed to the film or oxide layer resistance and a large loop associated with charge transfer resistance. The inhibitor adsorption was under Langmuir’s adsorption model. ΔG0ads values point to the presence of physical and chemical adsorption. Results of quantum chemical calculations showed that NPT has better interaction with copper than NPTH+. NICS of NPT in benzene or thiazole rings was less negative compared to NICS of NPTH+. Thus NPT shows less aromaticity compared with NPTH+, showing NPT can have better interaction with copper than NPTH+. NPT had more negative Eint value and more interactions with the Cu relative to NPTH+, this result was in agreement with the results of quantum chemical calculations.

Originality/value

NPT is an efficient corrosion inhibitor for copper in HCl. Theoretical calculations showed that NPT can have better interaction with copper than NPTH+. The results of the theoretical studies were in good agreement with the experimental studies.

Details

World Journal of Engineering, vol. 20 no. 6
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 16 January 2007

A.K. Mishra, R. Balasubramaniam and S. Tiwari

The research work in this paper aims to focus on understanding the corrosion inhibition of 6061‐8 (vol.%) SiC in 3.5 per cent NaCl solution using different concentrations (250…

1710

Abstract

Purpose

The research work in this paper aims to focus on understanding the corrosion inhibition of 6061‐8 (vol.%) SiC in 3.5 per cent NaCl solution using different concentrations (250, 500, 750 and 1,000 ppm) of cerium and lanthanum chloride.

Design/methodology/approach

The corrosion inhibition of 6061‐SiC in 3.5 per cent NaCl solution using the rare earth chloride inhibitors was analyzed by different electrochemical techniques. The techniques employed were linear polarization, Tafel extrapolation and electrochemical impedance spectroscopy (EIS). Further, surface characterization, before and after inhibitor addition, was studied using scanning electron microscopy (SEM) and energy dispersive analysis using X‐ray.

Findings

It was observed that the polarization resistance increased after addition of LaCl3 and CeCl3, with maximum increase noticed for 250 ppm LaCl3 and 1,000 ppm CeCl3. CeCl3 addition showed better improvement in polarization resistance value compared with LaCl3 addition. Pitting nucleation resistance also increased with addition of LaCl3 and CeCl3, with maximum obtained for 250 ppm LaCl3 and 500 ppm CeCl3. EIS studies showed that there was a significant increase in resistance of areas not covered by the surface film after addition of LaCl3 and CeCl3, when compared with the case without inhibitor, with a maximum increase observed with 1,000 ppm CeCl3. Rare earth chloride addition resulted in an increase in resistance on both cathodic intermetallic sites as well as the pitted regions by formation of precipitates of their oxide/hydroxide on those locations. This gave the high pitting nucleation resistance as well as improved corrosion resistance.

Research limitations/implications

It was observed that optimum concentrations of CeCl3 and LaCl3 resulted in good corrosion resistance properties on 6061‐SiC in 3.5 per cent NaCl solutions. Even small quantities of these inhibitors resulted in high corrosion resistance. However, it should be noted that both LaCl3 and CeCl3 did not follow a simple increase in corrosion resistance with composition, despite both being rare earth chloride inhibitors, and this issue merits further research.

Practical implications

Metal matrix composites (MMC) are of great use in the aerospace, military and automotive industries due to their good mechanical strength/density and stiffness/density ratios. A typical example might be the reinforcement of Al alloys with SiC particulates, which leads to a new generation of engineering materials. However, the addition of a reinforcing phase can cause discontinuities in any protective surface film, increasing the number of sites where corrosion can be initiated and rendering the composite liable to severe attack. Thus, this research work was performed to investigate if a suitable concentration of lanthanide salts (LaCl3 and CeCl3) could be identified that could improve both uniform and pitting corrosion resistance.

Originality/value

Earlier studies on the corrosion inhibition of 6061‐SiC used cerium conversion coatings. More recently (i.e. during the last 1‐2 years) work has started on lanthanum conversion coating on Al alloys. However, little work has been carried out on use of these lanthanide salts (CeCl3 and LaCl3) as corrosion inhibitors for 6061‐SiC. The present research work was performed in order to better understand the effectiveness of these inhibitors to reduce corrosion attack on 6061‐8(vol.%) SiC.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 2 January 2018

Behnam Abdollahi, Daryoush Afzali and Zahra Hassani

SiO2 and SiO2-ZrO2 nanocomposites were coated by sol–gel dipping method on carbon steel 178 (178 CS). Nanostructure and phase properties of nanocomposite coating were…

281

Abstract

Purpose

SiO2 and SiO2-ZrO2 nanocomposites were coated by sol–gel dipping method on carbon steel 178 (178 CS). Nanostructure and phase properties of nanocomposite coating were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared studies. Electrochemical polarization and electrochemical impedance spectroscopy (EIS) tests were used to study the corrosion behavior of 178 CS that was coated with SiO2-ZrO2 nanocomposite and SiO2 coating in 3.5 per cent NaCl solution. The results indicated that SiO2-ZrO2 nanocomposite coating performed better in terms of corrosion resistance compared with SiO2 coating. The corrosion resistance of SiO2-ZrO2 nanocomposite coating could be increased significantly in by approximately three and seven times of that of SiO2 coating and bare 178 CS, respectively.

Design/methodology/approach

SiO2 and SiO2-ZrO2 nanocomposites were coated using sol–gel dipping method on carbon steel 178. Electrochemical polarization and EIS tests have been used to study the corrosion behavior of 178 CS that was coated with SiO2-ZrO2 nanocomposite and SiO2 coating in 3.5 per cent NaCl solution.

Findings

Results indicated that SiO2-ZrO2 nanocomposite coating performed better in terms of corrosion resistance compared with SiO2 coating. The corrosion resistance of SiO2-ZrO2 nanocomposite coating could be increased significantly in by approximately three and seven times of that of SiO2 coating and bare 178 CS, respectively.

Originality/value

The SiO2-ZrO2 nanocomposite coating film showed significant improvement in corrosion resistance of 178 CS. The highest polarization resistance of the nanocomposite coating film was 10,600 Ω/cm2 from SiO2-0.2 ZrO2.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

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