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1 – 10 of over 1000Guotao Zhang, Zan Zhang, Zhaochang Wang, Yanhong Sun, Baohong Tong and Deyu Tu
The lubricating fluid stored in the porous matrix will spontaneously exude to supplement the lubricating film in the damaged area, thus ensuring the long-term self-lubricating…
Abstract
Purpose
The lubricating fluid stored in the porous matrix will spontaneously exude to supplement the lubricating film in the damaged area, thus ensuring the long-term self-lubricating function of the porous surface. To reveal the repair mechanism of oil film, it is necessary to understand the flow characteristics of oil in micropores. The purpose of this study guides the design of micropore structure to realize the rapid exudation of oil to the porous surface and the rapid repair of the lubricating film.
Design/methodology/approach
In this paper, cylindrical orifice, convergent orifice and divergent orifice were studied. The numerical model of lubricating oil exudation in micropores was established. The distribution characteristics of oil pressure, velocity and three-phase contact line in the process of oil exudation were investigated. The effects of different orifice shapes and orifice structure parameters on the pinning and spreading characteristics of oil droplet were analyzed. Then the internal mechanisms of oil droplet formation and spread on the orifice surface were summarized.
Findings
The results show that during the process of oil exudation, the three-phase contact line of the oil drop is pinned once at the edge of the cylindrical and convergent orifice. Compared with the three orifice structures, the inlet pressure of the oil drop is low, and the oil velocity at the pinning point is stable in the divergent orifice. Resulting in favorable oil exudation. It is easier for oil droplet to depin by appropriately reducing the wall wetting angle, increasing the aperture or controlling the wall inclination angle. Ensure the self-healing and long-lasting lubrication film of porous oil-bearing surfaces.
Practical implications
The effect of pore structure on the flow behavior of lubricating fluid has always been concerned. But the mechanism by which different orifice shape affect the pinning behavior of oil droplets is not yet clear, which is crucial for understanding the self-healing mechanism of oil films on porous surfaces. It is meaningful to analyze the mechanism of oil exudation and spreading on the porous surface of oil in the special orifice, to optimize the design of the orifice structure.
Originality/value
Orifice shape has influence on internal flow field parameters. There is no report on the influence of orifice shape on the film formation process of oil seepage and diffusion from pores. The effects of different orifice shapes and orifice structure parameters on the characteristics of oil droplet pinning and diffusion were studied.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0118/
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A. Syafiq, A.K. Pandey, Vengadaesvaran Balakrishnan, Syed Shahabuddin and Nasrudin Abd Rahim
This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles.
Abstract
Purpose
This paper aims to investigate the thermal stability and hydrophobicity of difference alkyl chain of silanes with silicon (Si) micro- and nanoparticles.
Design/methodology/approach
Sol-gel methods have been used to design superhydrophobic glass substrates through surface modification by using low-surface-energy Isooctyl trimethoxysilane (ITMS) and Ethyl trimethoxysilane (ETMS) solution. Hierarchical double-rough scale solid surface was built by Si micro- and nanoparticles to enhance the surface roughness. The prepared sol was applied onto glass substrate using dip-coating method and was dried at control temperature of 400°C inside the tube furnace.
Findings
The glass substrate achieved the water contact angle as high as 154 ± 2° and 150.4 ± 2° for Si/ITMS and Si/ETMS films, respectively. The Si/ITMS and Si/ETMS also were equipped with low sliding angle as low as 3° and 5°, respectively. The Si micro- and nanoparticles in the coating system have created nanopillars between them, which will suspend the water droplets. Both superhydrophobic coatings have showed good stability against high temperature up to 200°C as there are no changes in WCA shown by both coatings. Si/ITMS film sustains its superhydrophobicity after impacting with further temperature up to 400°C and turns hydrophobic state at 450°C.
Research limitations/implications
Findings will be useful to develop superhydrophobic coatings with high thermal stability.
Practical implications
Sol method provides a suitable medium for the combination of organic-inorganic network to achieve high hydrophobicity with optimum surface roughness.
Originality/value
Application of different alkyl chain groups of silane resin blending with micro- and nanoparticles of Si pigments develops superhydrophobic coatings with high thermal stability.
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Olayinka Moses, Dimu Ehalaiye, Matthew Sorola and Philippe Lassou
The purpose of this study is to examine the Nigerian Extractive Industry Transparency Initiative’s (NEITI) ineffectiveness in delivering public accountability to Nigerian…
Abstract
Purpose
The purpose of this study is to examine the Nigerian Extractive Industry Transparency Initiative’s (NEITI) ineffectiveness in delivering public accountability to Nigerian citizens. Although this failure is recognised in prior literature, the authors contend that NEITI’s role is obscured by one-sided links to external factors.
Design/methodology/approach
The conceptual framework presented in this study is built around Dillard and Vinnari’s (2019) distinction between different accountability systems and Brown and Dillard’s (2020) complimentary insights on the technologies of hubris and humility. The analytical framework draws from Grant and Keohane’s (2005) modes of accountability, which the authors use to articulate conflicting accountability demands (to-whom and for-what) of NEITI’s operating relationships. Combined, the authors analyse official documents, media, reports and interview responses from members of NEITI’s National Stakeholders Working Group.
Findings
This study surfaces a variety of intersecting interests across NEITI’s operational relationships. Some of these interests are mutually beneficial like that of Donors and the Extractive Industries Transparency Initiative. Others run counter to each other, such as NEITI’s relationship to the Presidency which illustrates a key source of NEITI’s ineffectiveness. In discussing these interests, the authors articulate their connection to NEITI’s design as an accountability system and its embedded limitations.
Originality/value
The authors provide incremental understanding of prior insight regarding NEITI’s ineffectiveness by drawing attention to its fundamental design as an accountability system and its failure to deliver public accountability. To illuminate these failures, the authors also map NEITI’s competing accountability demands – the nexus of accountability – to demonstrate the complex socio-political reality within which NEITI is expected to operate. The authors posit that NEITI’s ineffectiveness has as much to do with NEITI itself, as it does with external factors like the quality of information disclosed and the unique Nigerian context.
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Amirul Syafiq, Nasrudin Abd. Rahim, Vengadaesvaran Balakrishnan and A.K. Pandey
This paper introduced the simple synthesis process of self-cleaning coating with fog-resistance property using hydrophobic polydimethylsiloxane (PDMS) polymer and nano-calcium…
Abstract
Purpose
This paper introduced the simple synthesis process of self-cleaning coating with fog-resistance property using hydrophobic polydimethylsiloxane (PDMS) polymer and nano-calcium carbonate (nano-CaCO3) and titanium dioxide (TiO2).
Design/methodology/approach
The synthesis method of PDMS/nano-CaCO3-TiO2 is based on sol-gel process. The crosslinking between PDMS and nanoparticles is driven by the covalent bond at temperature of 50°C. The 3-Aminopropyltriethoxysilane is used as binder for nanoparticles attachment in polymer matrix. Two fabrication methods are used, which are dip- and spray-coating methods.
Findings
The prepared coated glass fulfilled the requirement of standard self-cleaning and fog-resistance performance. For the self-cleaning test BS EN 1096-5:2016, the coated glasses exhibited the dust haze value around 20%–25% at tilt angle of 10°. For the antifog test, the coated glasses showed the fog haze value were below 2% and the gloss value were above 85%. The obtained results completely achieved the standard antifog value ASTM F659-06 protocol.
Research limitations/implications
Findings will provide an infrastructure support for the building glass to enhance building’s energy efficiency, cleaning performance and friendly environment.
Practical implications
This study proposed the simple synthesis method using hydrophobic polymer and nano-CaCO3 and nano-TiO2, which can achieve optimum self-cleaning property at low tilt angle and fog-resistance performance for building glass.
Social implications
The research findings have high potential for building company, cleaning building company and government sector. The proposed project capable to reduces the energy consumption about 20% per annum due to labor cost, time-consuming and safety during manual cleaning.
Originality/value
The novel method to develop self-cleaning coating with fog-resistance using simple synthesis process and fabrication method for building glass application.
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Yang Zhou, Zhong Li, Yuhe Huang, Xiaohan Chen, Xinggang Li, Xiaogang Hu and Qiang Zhu
Laser powder bed fusion (LPBF) in-situ alloying is a recently developed technology that provides a facile approach to optimizing the microstructural and compositional…
Abstract
Purpose
Laser powder bed fusion (LPBF) in-situ alloying is a recently developed technology that provides a facile approach to optimizing the microstructural and compositional characteristics of the components for high performance goals. However, the complex mass and heat transfer behavior of the molten pool results in an inhomogeneous composition distribution within the samples fabricated by LPBF in-situ alloying. The study aims to investigate the heat and mass transfer behavior of an in-situ alloyed molten pool by developing a three-dimensional transient thermal-flow model that couples the metallurgical behavior of the alloy, thereby revealing the formation mechanism of composition inhomogeneity.
Design/methodology/approach
A multispecies multiphase computational fluid dynamic model was developed with thermodynamic factors derived from the phase diagram of the selected alloy system. The characteristics of the Al/Cu powder bed in-situ alloying process were investigated as a benchmark. The metallurgical behaviors including powder melting, thermal-flow, element transfer and solidification were investigated.
Findings
The Peclet number indicates that the mass transfer in the molten pool is dominated by convection. The large variation in material properties and temperature results in the presence of partially melted Cu-powder and pre-solidified particles in the molten pool, which further hinder the convection mixing. The study of simulation and experiment indicates that optimizing the laser energy input is beneficial for element homogenization. The effective time and driving force of the convection stirring can be improved by increasing the volume energy density.
Originality/value
This study provides an in-depth understanding of the formation mechanism of composition inhomogeneity in alloy fabricated by LPBF in-situ alloying.
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Suehail Aijaz Shah, Manzoor Ahmad Tantray and Jan Mohammad Banday
Durability of concrete can be enhanced by reducing the pore size/volume of pores or by entrapping the pores. This can be achieved by adding concrete admixtures that have particle…
Abstract
Purpose
Durability of concrete can be enhanced by reducing the pore size/volume of pores or by entrapping the pores. This can be achieved by adding concrete admixtures that have particle size finer than cement. In this study, GNP, having particle size much smaller than cement, has been introduced/added to concrete mix to control the pore size in concrete to tape out the contribution of GNP in the durability enhancement of concrete.
Design/methodology/approach
Different concrete mixes, at various water–cement ratios and amounts of graphene, have been manufactured to produce concrete containing three different %ages of GNP, i.e. 0%, 0.05% and 0.1%. To demonstrate the effect on durability of the concrete through the addition of GNP, these concrete samples have been subjected to repeated Freeze-Thaw cycles. Followed by testing after 28 days of curing, including weight loss, water absorption and strength, which are directly related to the durability aspect of concrete.
Findings
It has been observed that the addition of GNP to concrete mixes reduces the weight loss and pore size distribution and enhances tensile and compressive strength of concrete, thereby increasing the durability of concrete in unfavorable circumstances like freeze-thaw i.e. alternate hot and cold weather conditions.
Originality/value
This investigation presents original piece of experimental work conducted on modified concrete (GNP-based concrete). The aim is to construct the civil infrastructure in deep-cold region with increased life span and better performance.
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Debasmita Mohanty, Krishnan Kanny, Smita Mohanty and Sanjay K. Nayak
The purpose of this study is to reduce the application of petroleum in automobile paint industry by replacing it with bio-based castor oil along with nano fillers to synthesize…
Abstract
Purpose
The purpose of this study is to reduce the application of petroleum in automobile paint industry by replacing it with bio-based castor oil along with nano fillers to synthesize automobile base coat (BC).
Design/methodology/approach
Bio-based polyurethane (PU) coating applicable in automobile BC was synthesized by using modified castor oil incorporated with nano silica (NS) and titanium-based pigment particles. The influential characteristics of the coating was studied by carrying out cross-cut tape test, abrasion resistance, pencil hardness, lap-shear, thermo gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and acid, alkali and oil resistance tests.
Findings
Incorporation of NS particles, along with titanium-based pigment particles in optimized ratio into the paint matrix, increases the mechanical, chemical and oil resistance properties and hydrophobicity of the BC, and the findings are compared with the petro-based commercial BC.
Research limitations/implications
There is no significant improvement in thermal properties of the paint matrix, and it is less thermally stable than the commercial BC.
Practical implications
The paint developed through this study provides a simple and practical solution to reduce the petro-based feed-stock in automobile paint industry.
Originality/value
The current work which reports the use of ecofriendly PU BC for automobile paint applications is novel and findings of this study are original.
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Zaheer Abbas, Sabeeh Khaliq, Sana Usman and Muhammad Yousuf Rafiq
The coating process is broadly employed in the manufacturing of wallpapers, adhesive tapes, wrapping, protection of fabrics and metals, X-ray and photographic films…
Abstract
Purpose
The coating process is broadly employed in the manufacturing of wallpapers, adhesive tapes, wrapping, protection of fabrics and metals, X-ray and photographic films, beautification, books and magazines, film foils, magnetic records, coated paper, etc.
Design/methodology/approach
In this study, an incompressible flow of non-Newtonian fluid is modeled to inspect the rheological behavior of finite coating thickness in the reverse roll coating process. With the assistance of lubrication approximation theory (LAT), the dimensionless form of governing expressions is simplified. Exact solutions for distributions for velocity, flow rate, temperature and pressure gradient attained utilizing perturbation technique and their variation is presented as well as discussed in graphs. Meanwhile, some important factors from an engineering perspective including coating thickness and transition point were calculated mathematically and are displayed in a tabular manner. Also, streamlines are drawn to observe the flow pattern.
Findings
Prandtl fluid parameters provide a controlling factor to regulate the flow rate, velocity, coating thickness, and pressure gradient leading to an efficient coating process. Moreover, the Brinkman number and Prandtl fluid parameters significantly improve the temperature distribution.
Originality/value
In the literature, this study fills a gap in the theoretical prediction of coating thickness rheologically influenced by Prandtl fluid in reverse roll coating process.
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Abhishek Kumar Sharma and Shaligram Tiwari
This paper aims to carry out numerical study on growth of a single bubble from a curved hydrophilic surface, in nucleate pool boiling (NPB). The boiling performance associated…
Abstract
Purpose
This paper aims to carry out numerical study on growth of a single bubble from a curved hydrophilic surface, in nucleate pool boiling (NPB). The boiling performance associated with NPB on a curved surface has been analyzed in contrast to a plane surface.
Design/methodology/approach
Commercial software ANSYS Fluent 2021 R1 has been used with its built-in feature of interface tracking based on volume of fluid method. For water as the working fluid, the effect of microlayer evaporation underneath the bubble base has been included with the help of user-defined function. The phase change behavior at the interface of vapor bubble has been modeled by using “saturated-interface-volume” phase change model.
Findings
An interesting outcome of the present study is that the bubble departure gets delayed with increase in curvature of the heating surface. Wall heat flux is found to be higher for a curved surface as compared to a plane surface. Effect of wettability on the time for bubble growth is relatively more for the curved surface as compared to that for a plane surface.
Originality/value
Effect of surface curvature has been investigated on bubble dynamics and also on temporal variation of heat flux. In addition, the impact of surface wettability along with the surface curvature has also been analyzed on bubble morphology and spatial variation of heat flux. Furthermore, the influence of wall superheat on the bubble growth and also the wall heat flux has been studied for fixed angle of contact and varying curvature.
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Zhichuang Qi, Jingshan Chen, Zhangmi Huang, Chunyan Hu and Baojiang Liu
This paper aims to prepare Poly(Styrene-Butyl acrylate-Methacrylic acid) @Poly Gallic acid-Fe3+ photonic crystal composite inks [P(St-BA-MAA)@PGA-Fe3+ PCCI, @ means the PGA-Fe3+…
Abstract
Purpose
This paper aims to prepare Poly(Styrene-Butyl acrylate-Methacrylic acid) @Poly Gallic acid-Fe3+ photonic crystal composite inks [P(St-BA-MAA)@PGA-Fe3+ PCCI, @ means the PGA-Fe3+ is loaded on the microspheres] and construct noniridescent structural colors on fabric substrates, with the goal of improving the visibility of structural colors.
Design/methodology/approach
P(St-BA-MAA)@PGA-Fe3+ PCCI were prepared by coating P(St-BA-MAA) microspheres with a metal-polyphenol network formed by gallic acid (GA, C7H6O5) and Fe3+. The assembly effects of the inks were explored under different conditions, including pH, temperature, concentration and surface tension. The optimal self-assembly conditions of the inks were determined using the controlled variable method.
Findings
The results demonstrated the successful preparation of P(St-BA-MAA)@PGA-Fe3+ PCCI. The metal polyphenol network film composed of GA and Fe3+ was successfully coated on the surface of P(St-BA-MAA) seed microspheres. The assembly mechanism of the inks was investigated, indicating that at a diethylene glycol (DEG, C4H10O3) concentration of 0.3 wt% and pH of 7, bright noniridescent structural colors could be formed on fabric surfaces after self-assembly by PCCI at 60 °C for 10 min. Furthermore, the mechanical fastness of the structural colors was enhanced due to the adherence of the soft shell composed of P(St-BA-MAA) and GA.
Originality/value
Utilizing a cost-effective approach and a diverse array of readily available raw materials, we have successfully prepared P(St-BA-MAA)@PGA-Fe3+ PCCI, which boasts superior performance and offers fabrics a range of unique coloring styles. This innovation paves the way for potential applications of structural colors in practical production, thereby broadening their realm of utility.
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