Search results

1 – 10 of 685
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 1 August 2000

Zaki Ahmad, I.M. Allam and B.J. Abdul Aleem

The eastern coast of Saudi Arabia has one of the most corrosive environments in the world. Dhahran is therefore an ideal location for the study of atmospheric corrosion. One out…

1761

Abstract

The eastern coast of Saudi Arabia has one of the most corrosive environments in the world. Dhahran is therefore an ideal location for the study of atmospheric corrosion. One out of every seven cars in the region is corroded. The atmosphere is contaminated by SO2 and a high concentration of suspended particulate matter (SPM) containing sand, salt and carbon particles, exceeding the World Health Organization (WHO) and Middle East Environmental Protection Agency (MEPA) limits most of the time. Corrosion proceeds in the Dhahran atmosphere at a R.H. as low as 40 per cent. At locations close to the sea (1.5 Km), β‐FeOOH is the major corrosion product and α‐ and γ‐FeOOH with some aluminates, silicates and hydrocarbons the minor products. At a location remote from the sea α‐ and γ‐FeOOH are found to be the major corrosion products as shown by XRD and FTIR spectroscopy. The concentration of hydrogen ions, chloride ions and SO2 appears to control the corrosion process during the initial exposure period up to one year and the adsorption of anions on the corrosion product films in the later period.

Details

Anti-Corrosion Methods and Materials, vol. 47 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Abstract

Purpose

This paper aims to achieve two main objectives. First, to introduce to the literature a new versatile active building block, namely, voltage differencing differential voltage current conveyor (VD-DVCC) for analog signal processing applications. Second, to design a novel electronically tunable mixed-mode universal filter. The designed filter provides low-pass, high-pass, band-pass, band-reject and all-pass responses in voltage-mode (VM), current-mode (CM), trans-impedance-mode (TIM) and trans-admittance-mode (TAM).

Design/methodology/approach

The proposed filter uses two VD-DVCCs, three resistors and two capacitors. All the capacitors used are grounded, which is advantageous from the monolithic integration point of view. The VD-DVCC is designed and validated in Cadence software using CMOS 0.18 µm process design kit from Silterra Malaysia at a supply voltage of ±1 V.

Findings

The proposed novel filter enjoys many attractive features including as follows: the ability to operate in all four modes, no requirement of capacitive matching, tunability of quality factor (Q) independent of pole frequency, availability of both inverting and non-inverting outputs for VM and TIM mode, high output impedance explicit current output for CM and TAM, no requirement for double/negative input signals (voltage/current) for response realization and low active and passive sensitivities. The filter is designed for a pole frequency of 5.305 MHz. The obtained results bear a close resemblance with the theoretical findings.

Originality/value

The proposed novel filter structure requires a minimum number of active and passive components and provides operation in all four operating modes. The filter will find application in structures of mixed-mode systems.

Details

Circuit World, vol. 48 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Access Restricted. View access options
Article
Publication date: 1 January 2016

Ramazan Kahraman, Huseyin Saricimen, Zuhair Omar Malaibari and Md Abdur Rauf

The purpose of this study was to investigate the performances of two inhibitors in controlling corrosion of steel products in industrial and marine atmosphere.

124

Abstract

Purpose

The purpose of this study was to investigate the performances of two inhibitors in controlling corrosion of steel products in industrial and marine atmosphere.

Design/methodology/approach

Corrosion rates were determined by weight loss measurements. At certain periods of atmospheric exposure, the (disc shape) specimens were retrieved and studied by scanning electron microscopy and energy-dispersive spectrometry surface analysis techniques.

Findings

Both inhibitors were effective against corrosion of steel in the early stages of the atmospheric exposure (for about two months). With further exposure to the atmosphere, their inhibition effectiveness deteriorated and was totally lost within four months. Analysis of the specimens before exposure showed that the inhibitor film was thin for both treatments, and the unexposed treated surface for both inhibitors appeared similar to the untreated unexposed specimen surface. Characterization of the specimens at different exposure periods showed fewer corrosion blisters on dicyclohexylamine nitrite- and sodium benzoate-treated surfaces than on untreated specimens.

Originality/value

The objective of this study was to characterize the surfaces of the steel products produced locally during their exposure to the industrial and marine atmosphere of the Arabian Gulf region after being treated by sodium benzoate and dicyclohexylamine nitrite in controlling the corrosion of local mild steel products. According to the literature review, this study is original and will add value to the studies of inhibition of steel corrosion under similar environments.

Details

Anti-Corrosion Methods and Materials, vol. 63 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 1 April 2004

A. Al‐Mathami, H. Saricimen, R. Kahraman, M. Al‐Zahrani and S. Al‐Dulaijan

The purpose of this study was to evaluate the effectiveness of sodium dihydrogen orthophosphate as an inhibitor to slow down or prevent atmospheric corrosion of the local mild…

703

Abstract

The purpose of this study was to evaluate the effectiveness of sodium dihydrogen orthophosphate as an inhibitor to slow down or prevent atmospheric corrosion of the local mild steel during storage in the Arabian Gulf region. In light of the results of some preliminary studies, sodium dihydrogen orthophosphate was selected for further evaluation against atmospheric corrosion of steel after it was applied at 10 mM concentration for 1 day at room temperature.

Details

Anti-Corrosion Methods and Materials, vol. 51 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 1 October 2002

R. Kahraman, A.A. Al‐Mathami, H. Saricimen, N. Abbas and S.U. Rahman

The weather in the Arabian Gulf region constitutes an environment that is corrosive to carbon steel. In the Gulf region, atmospheric corrosion is aggravated further by the high…

848

Abstract

The weather in the Arabian Gulf region constitutes an environment that is corrosive to carbon steel. In the Gulf region, atmospheric corrosion is aggravated further by the high salinity of Gulf sea‐water. In addition, sulphur dioxide and deposits from combustion products tend to make the atmosphere in the Gulf region even more corrosive. Various inhibitors are reported in the literature that can help in the prevention of metal corrosion in aqueous environments. Among these, sodium dihydrogen orthophosphate, sodium benzoate, sodium nitrite and sodium nitrate were obtained and the effectiveness of certain corrosion inhibitors on carbon steel specimens was examined in a simulated atmospheric corrosion environment containing 2% NaCl and 1% Na2SO4 with various inhibitor concentrations. Test specimens were prepared from locally produced carbon steel reinforcing bars. It was found as a result of the test programme that treatment of the steel with 10 or 100mM sodium dihydrogen orthophosphate for one day at room temperature resulted in the best inhibition of corrosion. The results also demonstrated that inhibitors such as sodium benzoate and sodium nitrite were only similarly effective, as was sodium nitrate. Plans further study to examine the inhibition performance of sodium dihydrogen orthophosphate under actual atmospheric conditions.

Details

Anti-Corrosion Methods and Materials, vol. 49 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 3 February 2020

Utino Worabo Woju and A.S. Balu

Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design and…

207

Abstract

Purpose

Performance of the structure depends on design, construction, environment, utilization and reliability aspects. Other factors can be controlled by adopting proper design and construction techniques, but the environmental factors are difficult to control. Hence, mostly in practice, the environmental factors are not considered in the analysis and design appropriately; however, their impact on the performance of the structures is significant along with the design life. It is in this light that this paper aims to perform the time-dependent performance analysis of reinforced concrete structures majorly considering environmental factors.

Design/methodology/approach

To achieve the intended objective, a simply supported reinforced concrete beam was designed and detailed as per the Euro Code (EC2). The time-dependent design parameters, corrosion parameters, creep and shrinkage were identified through thorough literature review. The common empirical equations were modified to consider the identified parameters, and finally, the time-dependent performance of reinforced concrete beam was performed.

Findings

Findings indicate that attention has to be paid to appropriate consideration of the environmental effect on reinforced concrete structures. In that, the time-dependent performance of reinforced concrete beam significantly decreases with time due to corrosion of reinforcement steel, creep and shrinkage.

Originality/value

However, the Euro code, Ethiopian code and Indian code threat the exposure condition of reinforced concrete by providing corresponding concrete cover that retards the corrosion initiation time but does not eliminate environmental effects. The results of this study clearly indicate that the capacity of reinforced concrete structure degrades with time due to corrosion and creep, whereas the action on the structure due to shrinkage increases. Therefore, appropriate remedial measures have to be taken to control the defects of structures due to the environmental factors to overcome the early failure of the structure.

Details

Journal of Engineering, Design and Technology , vol. 18 no. 5
Type: Research Article
ISSN: 1726-0531

Keywords

Access Restricted. View access options
Article
Publication date: 2 May 2017

Anwar Ul-Hamid, Luai M. Al-Hems, Abdul Quddus, Abdulrashid I. Muhammed and Huseyin Saricimen

The purpose of this study was to determine the atmospheric corrosion behavior of aluminium (Al) exposed to the industrial and coastal environments of northeastern Arabian…

140

Abstract

Purpose

The purpose of this study was to determine the atmospheric corrosion behavior of aluminium (Al) exposed to the industrial and coastal environments of northeastern Arabian Peninsula for a period of 15 months.

Design/methodology/approach

The samples were exposed under atmospheric, underground and splatter zone conditions at the coastal region. Soil, groundwater, seawater and air particulate samples obtained from the exposure site were analyzed. Secondary electron microscopy was used to identify and study the microstructural features of the corrosion products formed at the surface of the test coupons. The corrosion rates of the samples were determined by the weight loss method.

Findings

The results showed that Al exhibited a moderate corrosion rate despite high degree of variation in temperature and humidity and large concentrations of chloride and sulfate in this region. Splatter zone environment was the most corrosive because of high chloride concentrations in seawater and the alternating wetting–drying cycles.

Originality/value

In this paper, corrosion of Al was evaluated in atmospheric, soil and splatter zone conditions along the northeastern coast of Arabian Peninsula and was also compared with the results of the test reported for other international locations.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 1 January 2006

A.N. Shuaib

The purpose of this paper is to develop a procedure for deciding on the limits of initial clearance to which tubesheet holes can be enlarged before replacement in heat exchanger…

437

Abstract

Purpose

The purpose of this paper is to develop a procedure for deciding on the limits of initial clearance to which tubesheet holes can be enlarged before replacement in heat exchanger maintenance.

Design/methodology/approach

An empirical model that relates the hardness of roller expanded tubes and ligaments to initial clearance is developed from experimental data to predict the extent of tolerable levels of over‐enlargement of tubesheet holes before the joint loses its structural integrity. The developed model serves as an additional criterion to decide whether to keep or discard a tubesheet having over‐enlarged holes during heat exchanger maintenance.

Findings

The current industrial criterion does not directly include the effect of material degradation for over‐enlarged holes. The empirical models indicate that both tubes and ligaments suffer strain hardenings. A new procedure is proposed to supplement the current industrial criterion.

Practical implications

The procedure will assist maintenance managers/engineers in deciding on the replacement of heat exchanger tubesheets. The combined criteria will have an impact on the cost of heat exchanger maintenance and plant downtime.

Originality/value

The procedure proposed in this paper adds to the industrial criterion another one that caters for the degradation in properties that the tube, tubesheet, and surrounding ligaments will be subjected to during roller expansion. In other words, it considers the strain hardening of the tube and tubesheet materials in setting the initial clearance between the tube and tubesheet that ensures adequate joint integrity.

Details

Journal of Quality in Maintenance Engineering, vol. 12 no. 1
Type: Research Article
ISSN: 1355-2511

Keywords

Access Restricted. View access options
Article
Publication date: 1 August 2002

M. Mobin, H.K. Sharma and S.K. Hasan

The aluminide and CeO2 and La2O3 containing aluminide coatings on carbon steel have been prepared by a pack cementation process. The influence of CeO2 and La2O3 additions on the…

621

Abstract

The aluminide and CeO2 and La2O3 containing aluminide coatings on carbon steel have been prepared by a pack cementation process. The influence of CeO2 and La2O3 additions on the oxidation rates of aluminide coatings has been investigated. The performance of coatings was studied by measuring oxidation kinetics, metallography, SEM and X‐ray diffraction analysis techniques. The oxidation‐resistance of coated carbon steel is discussed on the basis of a decrease in oxidation rates as well as adherence of oxide scales. The oxidation rates of carbon steel and aluminide coatings were markedly reduced in the presence of CeO2 and La2O3 in the temperature range of 700‐900°C. The oxidation rates were significantly affected by the morphology of oxide scales. In the case where the structure of oxides scales was not seriously disrupted due to decarburisation, the oxidation rates were significantly reduced.

Details

Anti-Corrosion Methods and Materials, vol. 49 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Access Restricted. View access options
Article
Publication date: 28 August 2024

Luo Yue, Yan Meng, Eunji Lee, Pengpeng Bai, Yingzhuo Pan, Peng Wei, Jie Cheng, Yonggang Meng and Yu Tian

The incorporation of phosphide additives is regarded as a highly effective strategy for enhancing the lubricative qualities of base oils. This study aims to assess the lubrication…

74

Abstract

Purpose

The incorporation of phosphide additives is regarded as a highly effective strategy for enhancing the lubricative qualities of base oils. This study aims to assess the lubrication behavior and efficacy of various phosphide additives in polyethylsiloxane (PES) through the employment of the Schwingum Reibung Verschleiss test methodology, across a temperature range from ambient to 300°C.

Design/methodology/approach

PES demonstrated commendable lubrication capabilities within the Si3N4/M50 system, primarily attributable to the Si-O frictional reaction film at the interface. This film undergoes disintegration as the temperature escalates, leading to heightened wear. Moreover, the phosphide additives were found to ameliorate the issues encountered by PES in the Si3N4/M50 system, characterized by numerous boundary lubrication failure instances. A chemical film comprising P-Fe-O was observed to form at the interface; however, at elevated temperatures, disintegration of some phosphide films precipitated lubrication failures, as evidenced by a precipitous rise in the coefficient of friction.

Findings

The results show that a phosphide reactive film can be formed and a reduction in wear rate is achieved, which is reduced by 64.7% from 2.98 (for pure PES at 300°C) to 1.05 × 10–9 μm3/N m (for triphenyl phosphite at 300°C).

Originality/value

The data derived from this investigation offer critical insights for the selection and deployment of phosphide additives within high-temperature lubrication environments pertinent to PES.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0139/

Details

Industrial Lubrication and Tribology, vol. 76 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

1 – 10 of 685
Per page
102050