Cheng Zhang, Liang Wu, Zilong Zhao, Guangsheng Huang, Bin Jiang, A. Atrens and Fusheng Pan
This paper aims to investigate microstructure, corrosion behavior and mechanical properties of Mg-4Li and Mg-4Li-3Al.
Abstract
Purpose
This paper aims to investigate microstructure, corrosion behavior and mechanical properties of Mg-4Li and Mg-4Li-3Al.
Design/methodology/approach
The microstructure was characterized by using scanning electron microscopy and electron backscatter diffraction. The corrosion behaviors were measured by hydrogen evolution and potentiodynamic polarization tests. The mechanical properties were evaluated by tensile tests.
Findings
The addition of Al results in the precipitation of some Mg-Al phase and Al3Li phase particles, and the formation of some fine recrystallized grains.
Originality/value
Mg-4Li-3Al showed a higher corrosion rate than that of Mg-4Li, attributed to the precipitate particles in Mg-4Li-3Al causing microgalvanic corrosion and the change of grain orientation. The addition of 3 Wt. per cent Al increased the tensile strength by solid solution strengthening, precipitation strengthening, refinement strengthening and texture strengthening, whilst the elongation decreased by almost half.
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D.N.P. Murthy, A. Atrens and J.A. Eccleston
The approach to maintenance management has changed over the last one hundred years. Over the last few years, the Reliability Engineering and Risk Management Group (RERMG) at the…
Abstract
The approach to maintenance management has changed over the last one hundred years. Over the last few years, the Reliability Engineering and Risk Management Group (RERMG) at the University of Queensland has developed an approach called the strategic maintenance management (SMM) approach. The paper outlines the approach and contrasts it with the current approaches. It then discusses the industry‐university partnership in the implementation of this approach and the current activities at the University of Queensland to assist industry in the implementation of the SMM approach.
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Nida Fatima and Raza Ali
This study aims to explore how businesswomen running micro and small enterprises (MSEs) use social media (SM) to engage customers. The study also investigates how SM (vs…
Abstract
Purpose
This study aims to explore how businesswomen running micro and small enterprises (MSEs) use social media (SM) to engage customers. The study also investigates how SM (vs traditional media) and customer engagement improve business performance.
Design/methodology/approach
This qualitative study is based on interviews with businesswomen.
Findings
Businesswomen use SM actively but not effectively. SM are used primarily for advertising and promotion. External factors, such as family and friends, are more influential in the decision of women to use SM in business. Women mostly use defensive rather than offensive strategies. Effective use of SM in conjunction with conventional marketing tools can improve customer engagement and increase business performance.
Practical implications
The research findings are valuable for marketing managers, women entrepreneurs and micro and small businesses in making decisions to effectively use SM.
Originality/value
This study investigates customer engagement from the owner/manager’s perspective in contrast to the general customer-centric approach. The study contributes analysing an important and scarcely explored area, which is the use of SM by women-run MSEs in less developed countries to engage consumers.
Propósito
Este estudio explora cómo las mujeres de negocios que dirigen micro y pequeñas empresas (MSE) utilizan las redes sociales para atraer a los clientes. El estudio también investiga cómo las redes sociales (frente a los medios tradicionales) y la involucración de los clientes mejoran el rendimiento empresarial.
Metodología
Este estudio cualitativo se basa en entrevistas con mujeres empresarias.
Conclusiones
Las mujeres empresarias utilizan las redes sociales de forma activa, pero no eficaz. Las redes sociales se utilizan principalmente para la publicidad y la promoción. Los factores externos, como la familia y los amigos, influyen más en la decisión de las mujeres de utilizar las redes sociales en los negocios. Las empresarias utilizan sobre todo estrategias defensivas en lugar de ofensivas. El uso eficaz de las redes sociales junto con las herramientas de marketing convencionales puede mejorar el compromiso de los clientes y aumentar el rendimiento de la empresa.
Implicaciones prácticas
Los resultados de la investigación son valiosos para las directivas de marketing, las mujeres empresarias y las micro y pequeñas empresas a la hora de tomar decisiones y para utilizar eficazmente las redes sociales.
Originalidad
Este estudio investiga el compromiso del cliente desde la perspectiva del propietario/gerente en contraste con el enfoque general centrado en el cliente. El estudio contribuye a analizar un área importante y escasamente explorada, que es el uso de las redes sociales por parte de las microempresas dirigidas por mujeres en los países menos desarrollados para involucrar a los consumidores.
目的
本研究探讨了经营微型和小型企业(MSEs)的女商人如何使用社交媒体来吸引客户。该研究还调查了社交媒体(相对于传统媒体)和客户参与如何提高企业绩效。
方法
这项定性研究是基于对女商人的采访。
研究结果
女商人积极使用社交媒体, 但并非有效。社交媒体主要用于广告和推广。外部因素, 如家庭和朋友, 对妇女在商业中使用社交媒体的决定更有影响力。女性大多使用防御性而非进攻性策略。将社交媒体与传统的营销工具有效地结合起来使用, 可以提高客户的参与度, 增加企业的业绩。
实践意义
研究结果对营销经理、女企业家和小微企业做出有效使用社交媒体的决定很有价值。
原创性
本研究从业主/经理的角度调查了客户参与度, 与一般的以客户为中心的方法不同。该研究有助于分析一个重要的、很少被探索的领域, 即欠发达国家的妇女经营的微型企业使用社交媒体来吸引消费者。
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Lyuyuan Wang, Jian Huang, Yong Peng, Yang Jia and Rong Ni
This paper aims to evaluate the corrosion resistance of fusion zones in different heat treated condition from laser welded Mg-Gd-Y alloys and analyze their intrinsic corrosion…
Abstract
Purpose
This paper aims to evaluate the corrosion resistance of fusion zones in different heat treated condition from laser welded Mg-Gd-Y alloys and analyze their intrinsic corrosion mechanism.
Design/methodology/approach
The corrosion behavior of fusion zone from laser-welded Mg-Gd-Y alloy joints in the as-welded, ageing and solution + ageing conditions was investigated in the 3.5 wt.% NaCl solution by immersion tests.
Findings
The corroded surface of as-welded fusion zone consists of dark and bright regions, and the bright regions were composed of high-density needle-like products, whereas some different extended direction of the cracks with lots of long ultrafine needle-shaped corrosion products appeared in the dark regions. The corrosion resistance of the fusion zone is slightly decreased after the ageing treatment.
Originality/value
The solution + ageing treated fusion zone exhibits the highest corrosion resistance than that of the as-welded and ageing treated state because of the full dissolution of the cathodic coarse eutectic compound, grains growth and relatively compact protective films. The inhomogeneous distribution of the β′ can somewhat improve the corrosion rate of solution + ageing treated fusion zone when compared with base metal.
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Charis Apostolopoulos, Argyro Drakakaki and Maria Basdeki
As it is widely known, corrosion is a major deterioration factor for structures which are located on coastal areas. Corrosion has a great impact on both the durability and seismic…
Abstract
Purpose
As it is widely known, corrosion is a major deterioration factor for structures which are located on coastal areas. Corrosion has a great impact on both the durability and seismic performance of reinforced concrete structures. In the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves – for unilateral and bilateral loadings – of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy). The paper aims to discuss this issue.
Design/methodology/approach
In the present study, two identical reinforced concrete columns were constructed and mechanical tests were organized to simulate seismic conditions. The tests were executed under the combination of a constant vertical force with horizontal, gradually increasing, cyclic loads. The implemented displacements, of the free end of the column, ranged from 0.2 to 5 percent. Prior to the initiation of the mechanical tests, the base of one of the two columns was exposed to predetermined accelerated electrochemical corrosion (at a height of 60 cm from the base). After the completion of the experimental loading procedure, the hysteresis curves of the two samples were presented and analyzed (in terms of strength, displacement and dissipated energy).
Findings
Analyzing the results, for both unilateral and bilateral loadings, a significant reduction of the seismic performance of the corroded column was highlighted. The corrosion damage imposed on the reference column resulted in the dramatic decrease of its energy reserves, even though an increase in ductility was recorded. Furthermore, more attention was paid to the consequences of the uneven corrosion damage, recorded on the steel bars examined, on ductility, hysteretic behavior and damping ratio.
Originality/value
In the present paper, the influence of the corrosion effects on the cyclic response of structural elements was presented and analyzed. The simulation of the seismic conditions was achieved by imposing, at the same time, a constant vertical force and horizontal, gradually increasing, cyclic loads. Finally, an evaluation of the performance of a column, under both unilateral and bilateral loadings, took place before and after corrosion.
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Mohamed Gobara and Mohamed Shamekh
This paper aims to study both the mechanical properties and the corrosion behavior of the synthesized in situ (TiC-TiB2) particulates/AZ91 magnesium matrix composite and compare…
Abstract
Purpose
This paper aims to study both the mechanical properties and the corrosion behavior of the synthesized in situ (TiC-TiB2) particulates/AZ91 magnesium matrix composite and compare the results with that of the conventional AZ91D alloy.
Design/methodology/approach
Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were used to study the surface morphology and crystalline structure. Mechanical compression tests were used to investigate the mechanical performance according to ASTM E9-89a. The corrosion behavior of the synthesized magnesium alloy was examined using both electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques in dilute Harrison solutions.
Findings
The microstructure of the Mg composite showed a uniform distribution of reinforcing phases. Also, the reinforcing phases were formed without residual intermediate phases. The addition of titanium and boron carbides not only enhanced the mechanical properties of the matrix but also improve its corrosion behavior.
Originality/value
This is the first time that magnesium matrix composite has been to synthesized with TiC and TiB2 particulates starting from starting from Ti and B carbides powder without adding aluminium using practical and low-cost technique (in situ reactive infiltration technique). This paper studies the corrosion behavior of synthesized Mg matrix in dilute Harrison solution and compares the results with that of conventional AZ91D.
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Qianqian Zhang and Huichen Zhang
The purpose of this paper is to evaluate the effect of micro-nano mixed super-hydrophobic structure on corrosion resistance and mechanism of magnesium alloys.
Abstract
Purpose
The purpose of this paper is to evaluate the effect of micro-nano mixed super-hydrophobic structure on corrosion resistance and mechanism of magnesium alloys.
Design/methodology/approach
A super-hydrophobic surface was fabricated on AZ91 and WE43 magnesium alloys by laser etching and micro-arc oxidation (MAO) with SiO2 nanoparticles coating and low surface energy material modification. The corrosion resistance properties of the prepared super-hydrophobic surfaces were studied based on polarization curves and immersion tests.
Findings
Compared with bare substrates, the corrosion resistance of super-hydrophobic surfaces was improved significantly. The corrosion resistance of super-hydrophobic surface is related to micro-nano composite structure, static contact angle and pretreatment method. The more uniform the microstructure and the larger the static contact angle, the better the corrosion resistance of the super-hydrophobic surface. The corrosion resistance of super-hydrophobic by MAO is better than that of laser machining. Corrosion of super-hydrophobic surface can be divided into air valley action, physical shielding, pretreatment layer action and substrate corrosion.
Originality/value
The super-hydrophobic coatings can reduce the contact of matrix with water so that a super-hydrophobic coating would be an effective way for magnesium alloy anti-corrosion. Therefore, the corrosion resistance properties and mechanism of the prepared super-hydrophobic magnesium alloys were investigated in detail.
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Argyro Drakakaki, Alkiviadis Apostolopoulos and Charis Apostolopoulos
The safety of reinforced concrete structures is generally related to the expected service life of their individual materials. Corrosion damage manifesting on steel reinforcement…
Abstract
Purpose
The safety of reinforced concrete structures is generally related to the expected service life of their individual materials. Corrosion damage manifesting on steel reinforcement is usually underestimated, although it greatly affects both load bearing capacity and plastic deformation limits of steel reinforcement. Corrosion damage degree has a great impact on the life expectancy of structures. This paper aims to discuss these issues.
Design/methodology/approach
In the present study, an effort has been made to examine and present critical parameters, which are significantly responsible for the differentiation of the corrosion damage level, as far as mass loss is concerned. Consequently, the size effect of the exposed – to the aggressive conditions – area of the specimen, as well as the volume of the protected (against corrosion) area, was examined in detail.
Findings
Differential aeration greatly affects the results of corrosion on the material, given that under both high and low oxygen concentration corrosion process is still ongoing.
Originality/value
Findings proceeded are worth mentioning, as they may contribute to a more pertinent evaluation of the corrosion damage (as far as mass loss is concerned), restricting the risk of erroneous predictions concerning the mechanical behavior of steel reinforcement.
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Jun Yang, Pei Zhang, Lihuizi Su, Fuan Yan and Zhou Yong
The aim of this work was to propose a method to prepare composite phosphate conversion coating (CPCC), including ternary phosphate conversion coating (TPCC) and binary phosphate…
Abstract
Purpose
The aim of this work was to propose a method to prepare composite phosphate conversion coating (CPCC), including ternary phosphate conversion coating (TPCC) and binary phosphate conversion coatings (BPCC), with one-step chemical conversion and to reveal and compare the corrosion resistance between TPCC and BPCC.
Design/methodology/approach
In this work, a calcium–manganese–zinc (Ca–Mn–Zn) TPCC was prepared on the surface of magnesium alloy (MA) AZ91D with one-step chemical conversion method; for Ca-Mn-Zn@TPCC, its microstructure was characterized with scanning electron microscope observation and scanning tunneling microscope detection, and its composition was characterized with energy dispersion spectroscopy and X-ray photoelectron spectroscopy analyses. Particularly, the corrosion resistance of Ca-Mn-Zn@TPCC and its comparison with Ca–Mn, Ca–Zn and Mn–Zn BPCCs were clarified with electrochemical and immersion measurements.
Findings
Ca-Mn-Zn@TPCC, which was composed of Ca, Mn, Zn, P and O, exhibited a mud-shaped with cracks microstructure, and the average crack width, terrain fluctuation and coating thickness were 0.61 µm, 23.78 nm and 2.47 µm, respectively. Ca-Mn-Zn@TPCC provided good corrosion resistance to MA AZ91D; in NaCl solution, the total degradation of Ca-Mn-Zn@TPCC consumed eight days; corrosion products with poor adhesion peeled out from Ca-Mn-Zn@TPCC-coated MA AZ91D spontaneously. Besides, the corrosion resistance of Ca-Mn-Zn@TPCC was better than that of Ca-Mn@BPCC, Ca-Zn@BPCC or Mn-Zn@BPCC.
Originality/value
The successful preparation of Ca-Mn-Zn@TPCC on MA AZ91D surface confirmed the proposed method to prepare CPCC with one-step chemical conversion was feasible; at the same time, it was further confirmed that for phosphate conversion coating, ternary coating had better corrosion resistance than binary coating did.
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Pengxiong Zhao, Wei Wu, Zeyu Ma and Yong Dan
This paper aims to investigate the corrosion evolution process of AZ91 magnesium alloy in 3.5 wt.% NaCl solution under different stresses by using in situ methods, thereby…
Abstract
Purpose
This paper aims to investigate the corrosion evolution process of AZ91 magnesium alloy in 3.5 wt.% NaCl solution under different stresses by using in situ methods, thereby evaluate the influence of stress on the corrosion sensitivity of AZ91 magnesium alloy, and discuss the potential mechanism.
Design/methodology/approach
A four-point bending method was used to apply different loads to the magnesium alloy samples, a charge coupled device camera and electrochemical impedance spectroscopy test being used for in situ study. Scanning electron microscopy and X-ray diffraction (XRD) analysis were performed for corrosion product and morphology characteristics.
Findings
The observation results show that the corrosion of AZ91 magnesium alloy becomes more and more serious with the increase in the stress and generated many corrosion products. Originally, corrosion products prevented alloy matrix from contacting the corrosive medium. However, the increase in the stress facilitated the emergence of the corrosion holes in the corrosion products, which provided the microscopic channels for corrosive solution to attack the Mg alloy matrix, and accelerated the corrosion of the magnesium alloy, resulting in a lot of corrosion pits on the magnesium alloy surface under the corrosion product layer.
Originality/value
The evolution information of corrosion process is crucial to explore the mechanism of corrosion. Currently, most researches about corrosion of magnesium alloy used traditional testing techniques to obtain corrosion information, lacking the direct tracking and monitoring of the corrosion evolution process. Hence, this paper focuses on in situ corrosion study of AZ91 magnesium alloy. The technology with spatial resolution capability observed the changes in magnesium alloy surface at different times in the corrosion process in situ. Meanwhile, the in situ electrochemical technology was used to monitor the changes in micro-electrochemical signals during the corrosion process of magnesium alloy under different stresses.