K. Jafarzadeh, T. Shahrabi, S.M.M. Hadavi and M.G. Hosseini
The paper aims to focus on the recognition of corrosion product morphologies of AA5083‐H321 corroding aluminum‐magnesium alloys used in the manufacture of aluminum high speed…
Abstract
Purpose
The paper aims to focus on the recognition of corrosion product morphologies of AA5083‐H321 corroding aluminum‐magnesium alloys used in the manufacture of aluminum high speed boats and submarines during flow induced corrosion in seawater.
Design/methodology/approach
All experiments were conducted in a 3.5 percent NaCl solution as the simulated marine environment. Hydrodynamic conditions were created by an rotating cylinder electrode (RCE) system. Morphological characterization of the surface was undertaken using SEM and EDAX techniques. Cyclic polarization tests were used to determine the electrochemical behavior of the alloy.
Findings
The results obtained reveal that the pit density on the sample surface increased with increasing the rotation speed. The enhanced flow condition also enhanced the tendency for intermetallic particles, including submicron size Al(Mg,Mn) inclusions, to promote pitting corrosion of the alloy. An interesting result was that crystallographic pitting occurred at rotation speeds greater than 5 m/s.
Practical implications
In the selection of corrosion control methods for high speed aluminum‐hulled boats, control of erosion corrosion was determined to be more important than any other form of corrosion.
Originality/value
Provides information about the contribution of mechanical and electrochemical corrosion phenomena in corrosion of high speed aluminum boats under hydrodynamic conditions. Characterization of new intermetallic particles in aluminum‐magnesium alloys that can promote pitting during flow induced corrosion in marine environments. Provides new information about the origin of crystallographic pitting attack on aluminum.
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K. Jafarzadeh, T. Shahrabi and S.M.M. Hadavi
The sulphidation behaviour of high contraction (HC) and low contraction (LC) chromium plated steel was studied in sulphur with a partial pressure of 1 atm at 1, 3, 5 and 7 h and…
Abstract
The sulphidation behaviour of high contraction (HC) and low contraction (LC) chromium plated steel was studied in sulphur with a partial pressure of 1 atm at 1, 3, 5 and 7 h and 0.1 and 0.01 atm at 5 h. The temperature was 600°C throughout the work. It was found that HC and LC chromium plating imparted significant sulphidation resistance to steel. It should be mentioned that by increasing sulphidation time and sulphur partial pressure, the hardness of chromium coating decreased. LC chromium coating had a lower thermal shock resistance than the HC coating. Thus, it was concluded that the HC chromium coating had the better sulphidation resistance.
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Vaira Vignesh Ramalingam, Padmanaban Ramasamy and Madhav Datta
The purpose of this study is to refine the microstructure and improve the corrosion behaviour of aluminium alloy AA5083 by subjecting it to friction stir processing (FSP).
Abstract
Purpose
The purpose of this study is to refine the microstructure and improve the corrosion behaviour of aluminium alloy AA5083 by subjecting it to friction stir processing (FSP).
Design/methodology/approach
FSP trials are conducted as per central composite design, by varying tool rotation speed, tool traverse speed and shoulder diameter at three levels. The microstructure is examined and the hardness is measured for both the base material and the processed workpieces. The corrosion behaviour of the base material and processed workpieces is studied using potentiodynamic polarization technique for three different testing temperatures, and the corrosion current and corrosion rate are calculated.
Findings
The results reveal that FSP refined the grains, dispersed secondary phases, increased the hardness and improved the corrosion resistance of most of the friction stir processed specimens than the base material at all the three testing temperatures. Grain refinement and fine dispersion of ß phase improves the hardness and corrosion resistance of most of the FSPed specimens. However partial dissolution of ß phase decreases the hardness in some of the specimens. Most of the FSPed specimens displayed more positive potential than the base material at all the testing temperatures representing a higher nobility than the base material, as a result of fine dispersion of secondary phase particles in the matrix. Large pits formed on the surface of the base specimen indicating a higher corrosion rate at all three testing temperatures. The SEM image of FSPed specimens reveals the occurrence of very few pits and minimal corrosion products on the surface, which indicates lower corrosion rate.
Originality/value
The corrosion mechanism of the friction stir-processed AA5083 specimens is found to be a combination of activation and concentration polarization.
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Akshya Kumar Guin, Manish Bhadu, Mohua Sinhababu, Tapan Kumar Rout and G. Udayabhanu
This paper aims to investigate the potential of sol-gel coating as replacement for hazardous hexavalent chrome passivation treatment for galvanised iron (GI) sheet. Generally…
Abstract
Purpose
This paper aims to investigate the potential of sol-gel coating as replacement for hazardous hexavalent chrome passivation treatment for galvanised iron (GI) sheet. Generally, corrosion resistance properties of the GI sheet are increased by hexavalent chrome passivation treatment. But hexavalent chrome is hazardous and not environment friendly.
Design/methodology/approach
The aim of this study was to understand the effect of nano zinc oxide (ZnO) on corrosion behaviour of sol-gel coating prepared by hydrolysis of the 3-(Glycidoxy propyl) methyl diethoxy silane (GPTMS) and tetra-ethyl-orthosilicate (TEOS). The morphology of the film was characterised by a scanning electron microscope (SEM). The corrosion resistance of the coated samples was evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation curve and salt spray test.
Findings
From a different corrosion resistance study, it has been observed that sol-gel coating doped with 1 per cent nano ZnO rendered maximum corrosion protection. Beyond 1 per cent of nano ZnO, corrosion resistance property of coated galvanised steel sheet decreased drastically which may be due to agglomeration of nano ZnO and high water permeability of coated galvanised steel sheet.
Research limitations/implications
The anti-corrosive property of the coating can be tested by means of atmospheric exposure which produces a real-time evaluation of the anti-corrosive nature of the coating under natural conditions rather than using an accelerated laboratory test.
Practical implications
It may be useful for other metal industry like aluminium. The work can be used as a guiding chemistry for development of chrome-free passivation for aluminium.
Social implications
It has the potential to replace hexavalent chrome passivation.
Originality/value
The use of nano ZnO in sol-gel polymer matrix for the development of corrosion resistant chrome-free polymer coating for galvanised steel sheet and its corrosion resistance study (EIS curve fitting, capacitance value and water permeability) is a novel approach in this research.
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Guangwei Liang, Zhiming Gao, Cheng-Man Deng and Wenbin Hu
The purpose of this study is to reveal the effect of nano-Al2O3 particle addition on the nucleation/growth kinetics, microhardness, wear resistance and corrosion resistance of…
Abstract
Purpose
The purpose of this study is to reveal the effect of nano-Al2O3 particle addition on the nucleation/growth kinetics, microhardness, wear resistance and corrosion resistance of Co–P–xAl2O3 nanocomposite plating.
Design/methodology/approach
The kinetics and properties of Co–P–xAl2O3 nanocomposite plating prepared by electroplating were investigated by electrochemical measurements, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Vickers microhardness measurement, SRV5 friction and wear tester and atomic force microscopy.
Findings
A 12 g/L nano-Al2O3 addition in the plating solution can transform the nucleation/growth kinetics of the plating from the 3D progressive model to the 3D instantaneous model. The microhardness of the plating increased with the increase of nano-Al2O3 content in plating. The wear resistance of the plating did not adhere strictly to Archard’s law. An even and denser corrosion product film was generated due to the finer grains, with a high corrosion resistance.
Originality/value
The effect of different nano-Al2O3 addition on the nucleation/growth kinetics and properties of Co–P–xAl2O3 nanocomposite plating was investigated, and an anticorrosion mechanism of Co–P–xAl2O3 nanocomposite plating was proposed.
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Jaber Valizadeh and Peyman Mozafari
Production of waste has been increased exponentially due to world industrialization and urban and machine life expansion. On the other hand, the outbreak of the COVID-19…
Abstract
Purpose
Production of waste has been increased exponentially due to world industrialization and urban and machine life expansion. On the other hand, the outbreak of the COVID-19 coronavirus quickly became a global crisis. This crisis has added a large amount of waste to urban waste. The purpose of this study is to create cooperation between municipal waste collector contractors.
Design/methodology/approach
Thus, a mathematical model is proposed under uncertain conditions, which includes the volume of municipal waste and infectious waste including personal protective equipment and used equipment for patients. To reduce total costs, the results are evaluated with four cooperative game theory methods such as Shapley value, t value, core center and least core. Ultimately, the saved cost by cooperation in each coalition is allocated fairly among the contractors. Finally, a comparison was made between the solution methods based on the value of the objective function and the solution time.
Findings
The results indicate that the proposed cooperative method increases cost savings and reduces the fine of residual waste. Therefore, it can be mentioned that this kind of cooperation would finally result in more incentives for contractors to form larger coalitions. Genetic algorithms were used to solve the large-scale model.
Originality/value
The proposed model boosts the current understanding of waste management in the COVID-19 pandemic. The paper adds additional value by unveiling some key future research directions. This guidance may demonstrate possible existing and unexplored gaps so that researchers can direct future research to develop new processes.
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Yuting Lv, Xing Ouyang, Yaojie Liu, Ying Tian, Rui Wang and Guijiang Wei
This paper aims to investigate the differences in hot corrosion behavior of the GTD222 superalloy and TiC/GTD222 composite in a mixed salt of 75% Na2SO4 and 25% K2SO4 at 900°C.
Abstract
Purpose
This paper aims to investigate the differences in hot corrosion behavior of the GTD222 superalloy and TiC/GTD222 composite in a mixed salt of 75% Na2SO4 and 25% K2SO4 at 900°C.
Design/methodology/approach
The GTD222 superalloy and TiC/GTD222 nickel-based composite were prepared using selective laser melting (SLM). Subsequently, the hot corrosion behavior of the two alloys was systematically investigated in a salt mixture consisting of 75% Na2SO4 and 25% K2SO4 (Wt.%) at 900°C.
Findings
The TiC/GTD222 composite exhibited better hot corrosion resistance compared to the GTD222 superalloy. First, the addition of alloying elements led to the formation of a protective oxide film on the TiC/GTD222 composites 20 h before hot corrosion. Second, TiC/GTD222 composite corrosion surface has a higher Ti content, after 100 h of hot corrosion, the composite corrosion surface Ti content of 10.8% is more than two times the GTD222 alloy 4% Ti. The Ti and Cr oxides are tightly bonded, effectively resisting the erosion of corrosive elements.
Originality/value
The hot corrosion behavior of GTD222 superalloy and TiC/GTD222 composites prepared by SLM in a mixed salt of 75% Na2SO4 and 25% K2SO4 was studied for the first time. This study provides insights into the design of high-temperature alloys resistant to hot corrosion.
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Ömer Utku Kahraman and Erdal Aydemir
The purpose of this paper is to manage the demand uncertainty considered as lower and upper levels for a medium-scale industrial distribution planning problem in a biobjective…
Abstract
Purpose
The purpose of this paper is to manage the demand uncertainty considered as lower and upper levels for a medium-scale industrial distribution planning problem in a biobjective inventory routing problem (IRP). In order to achieve this, the grey system theory is applied since no statistical distribution from the past data and incomplete information.
Design/methodology/approach
This study is investigated with optimizing the distribution plan, which involves 30 customers of 12 periods in a manufacturing company under demand uncertainty that is considered as lower and upper levels for a biobjective IRP with using grey demand parameters as a grey integer programming model. In the data set, there are also some missing demand values for the customers. So, the seven different grey models are developed to eliminat the effects on demand uncertainties in computational analysis using a piece of developed software considering the logistical performance indicators such as total deliveries, total cost, the total number of tours, distribution capacity, average remaining capacity and solution time.
Findings
Results show that comparing the grey models, the cost per unit and the maximum number of vehicle parameters are also calculated as the new key performance indicator, and then results were ranked and evaluated in detail. Another important finding is the demand uncertainties can be managed with a new approach via logistics performance indicators using alternative solutions.
Practical implications
The results enable logistics managers to understand the importance of demand uncertainties if more reliable decisions are wanted to make with obtaining a proper distribution plan for effective use of their expectations about the success factors in logistics management.
Originality/value
The study is the first in terms of the application of grey models in a biobjective IRP with using interval grey demand data. Successful implementation of the grey approaches allows obtaining a more reliable distribution plan. In addition, this paper also offers a new key performance indicator for the final decision.
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Kok Wei Poh, Cheng Huong Ngan, Ji Yin Wong, Tiang Koi Ng and Nadiah Mohd Noor
There was limited study available on successful intervention for central-line-associated bloodstream infection (CLABSI) done at nonintensive care unit (ICU) and resources-limited…
Abstract
Purpose
There was limited study available on successful intervention for central-line-associated bloodstream infection (CLABSI) done at nonintensive care unit (ICU) and resources-limited setting. The objective of this study was to design, implement and evaluate a strategy to reduce CLABSI rate in non-ICU settings at general medical wards of Hospital Tuanku Ja'afar Seremban.
Design/methodology/approach
Preinterventional study was conducted in one-month period of January 2019, followed by intervention period from February to March 2019. Postintervention study was conducted from April to July 2019. The CLABSI rates were compared between pre and postintervention periods. A multifaceted intervention bundle was implemented, which comprised (1) educational program for healthcare workers, (2) weekly audit and feedback and (3) implementation of central line bundle of care.
Findings
There was a significant overall reduction of CLABSI rate between preintervention and postintervention period [incidence rate ratio (IRR) of 0.06 (95 percent CI, 0.01–0.33; P = 0.001)].
Practical implications
CLABSI rates were reduced by a multifaceted intervention bundle, even in non-ICU and resource-limited setting. This includes a preinterventional study to identify the risk factors followed by a local adaption of the recommended care bundles. This study recommends resources-limited hospitals to design a strategy that is suitable for their own local setting to reduce CLABSI.
Originality/value
This study demonstrated the feasibility of a multifaceted intervention bundle that was locally adapted with an evidence-based approach to reduce CLABSI rate in non-ICU and resource-limited setting.
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W. Wan Nik, R. Rosliza, M. Zulkifli and D. Hui
The effect of different cooling methods on the corrosion behaviour at welded area of aluminium alloy 5083 was investigated by using weight loss study, potendynamic polarization…
Abstract
The effect of different cooling methods on the corrosion behaviour at welded area of aluminium alloy 5083 was investigated by using weight loss study, potendynamic polarization study and morphology study. All samples were cooled by using air cooling method and quenching method. There was an increase of weight loss for both cooling methods where samples with air cooling method showed lower percentage of weight loss as compared to samples with quenching methods. The corrosion rate gained from this study revealed that samples with air cooling method showed lower corrosion rate compared to samples with quenching method. In potentiodynamic polarization study, the value of corrosion current density, Icorr increased with respect to immersion period. This behaviour signifies the occurrence of porosity where the air cooled samples show lower value of Icorr compared to quenched samples. The increase in Icorr causes the value of polarization resistance, Rp to decrease and corrosion rate to increase. The morphology study conducted revealed the existence of porosity and caused pitting corrosion on quenched samples which proved the samples with quenching method was more corroded as compared to samples with air cooling method.