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1 – 10 of over 6000Xiaoli Kong, Bo Zhou, Jixiao Wang and Wenping Li
The purpose of this paper is to study the engineering application of diamond like carbon (DLC) coatings on the surfaces of piston pins and bucket tappets for a 2.0 L supercharged…
Abstract
Purpose
The purpose of this paper is to study the engineering application of diamond like carbon (DLC) coatings on the surfaces of piston pins and bucket tappets for a 2.0 L supercharged gasoline engine. The friction loss and durability of DLC-coated components were investigated.
Design/methodology/approach
The tribological characteristics were examined under oil-lubricated conditions in a CETR UMT reciprocating tribometer. In a motored engine test rig, friction loss torque test was performed to estimate the improvement in fuel economy. Fired engine durability bench tests of typical duration of 450 h were completed to access the durability and wear resistance of DLC coating. Before and after durability tests, coated and uncoated components were measured on the sliding surface by a profilometer technique.
Findings
Friction and wear test results show that DLC coating has low friction coefficient and reduces the wear rates by almost ten times compared to those of uncoated surfaces. Friction loss measurements indicate that DLC-coated tappets can reduce valve train friction loss by 29 per cent, and DLC-coated piston pins can reduce piston group friction by 11 per cent. Based on fired engine durability bench tests, it is evidenced that none of the coated tappets and pins show any noticeable peeling or delamination. Wear profiles analysis results indicate that DLC-coated engine components give rise to a substantial reduction in wear.
Originality/value
DLC coating applied onto the working surface of piston pin and bucket tappet can effectively reduce the friction loss of gasoline engine. DLC coating exhibits sufficient durability and improves friction and wear performance.
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The purpose of this paper is to discuss a method that can evaluate the friction durability of automatic transmission fluid.
Abstract
Purpose
The purpose of this paper is to discuss a method that can evaluate the friction durability of automatic transmission fluid.
Design/methodology/approach
A small clutch was used to test the friction durability. The method adopts a similar sequence to that of SAE No. 2. Three commercial oils were studied. One of them meets the specification of the GM's DEXRONIIE and the others meet the DEXRONIII.
Findings
The results showed that two commercial oils have different friction durability. Two further samples were blended in the lab and friction durability was researched by this method.
Originality/value
The results showed that the samples have a good durability. The research indicates that the method is quite capable of distinguishing between some samples. The results also indicate the difference between the DEXRON specifications at friction durability.
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Wu Huijun, Zhan Diao and Kaizuo Fan
The purpose of this paper is to focus on the durability of underwater non-dispersible concrete in seawater environment.
Abstract
Purpose
The purpose of this paper is to focus on the durability of underwater non-dispersible concrete in seawater environment.
Design/methodology/approach
In this paper, ten groups of underwater non-dispersible concrete mixtures were designed, and the anti-dispersibility and fluidity of the mixtures were tested.
Findings
The durability test analysis shows that different pouring methods have different effects on the durability of concrete. The durability of concrete poured on land is better than that poured in water. Different mineral admixtures have different effects on the durability of concrete: the frost resistance of the underwater non-dispersible concrete specimens with silica fume is the best; the impermeability and chloride ion permeability of the non-dispersible underwater concrete specimens with waterproofing agent are the best; and the alternation of wetting and drying has adverse effects on the durability indexes of the non-dispersible underwater concrete.
Originality/value
The durability of underwater non-dispersible concrete is tested and the results can be used for reference in engineering practice.
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Yajun Ma, Wancheng Zhao, Shenghua Li, Yuansheng Jin, Yucong Wang and Tung C. Simon
Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine…
Abstract
Purpose
Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine oils.
Design/methodology/approach
The lubricating durability D was defined based on definition of three characteristic points Pd, PS, Pi and three key time lengths Td, Ts, Ti. Two kinds of engine oils, respectively, belonging to GF‐2 and GF‐3 categories, were selected as samples to compare their lubricating durability.
Findings
Test results indicate the GF‐3 oil has much better lubricating durability than GF‐2 oil. With investigation of the topography and chemical composition changes of wear tracks along with the tribotests' time extending, the meanings of three characteristic points were discussed. Analysis indicates much better tribofilm, formed by the synergistic effect of Ca‐containing detergent with MoDTC/ZDTP in GF‐3 oil, is the major factor resulting in GF‐3 oil's longer lubricating durability.
Originality/value
Provides further research on lubricating durability, which is important for engine oil change and maintenance, as well as decreased cost and pollution to the environment, and improved energy conservation.
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Poonam Shekhawat, Gunwant Sharma and Rao Martand Singh
The purpose of this study is to investigate the effect of various heat conditions on the durability of eggshell powder (ESP)–flyash (FA) geopolymer subjected to wetting–drying…
Abstract
Purpose
The purpose of this study is to investigate the effect of various heat conditions on the durability of eggshell powder (ESP)–flyash (FA) geopolymer subjected to wetting–drying cycles.
Design/methodology/approach
In this study, two waste materials, ESP and FA, which are destined for landfills, were used as precursors to produce geopolymers in a sustainable manner. The mixture of Na2SiO3 and NaOH was used as a liquid alkaline activator in geopolymerization. The ESP and FA content were varied as 30, 50 and 70% and Na2SiO3/NaOH ratios were varied as 0.5, 1 and 2. Geopolymer samples were cured at three heat conditions: 25°C (ambient temperature), 50°C and 80°C for seven days prior to durability tests.
Findings
The results of this study revealed that the strength loss of the geopolymer decreases with an increase in curing temperature up to 50°C and then increases for higher temperature up to 80°C. Further, the strength loss of the geopolymer decreases with an increase in FA replacement and Na2SiO3/NaOH ratio. Geopolymer composites exhibited early strength development because of the inclusion of calcium-rich ESP. The weight loss of the ESP–FA geopolymer follows a similar pattern of strength loss. Geopolymer samples previously cured at optimum heat condition of 50°C for seven days exhibited higher durability.
Originality/value
The inclusion of calcium-rich ESP in FA-based geopolymer is novel research. As ESP–FA geopolymer composites show higher mechanical strength and higher durability compared to Indian standards, the potential use of this geopolymer can be in road subbases/subgrades.
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Tara L. Cavalline and David C. Weggel
Reuse of construction and demolition (C&D) waste as aggregates is becoming increasingly popular for a number of environmental and economic reasons. The purpose of this paper is to…
Abstract
Purpose
Reuse of construction and demolition (C&D) waste as aggregates is becoming increasingly popular for a number of environmental and economic reasons. The purpose of this paper is to explore this topic.
Design/methodology/approach
In this study, structural‐ and pavement‐grade portland cement concrete (PCC) mixtures were developed using crushed recycled brick masonry from a demolition site as a replacement for conventional coarse aggregate. Prior to developing concrete mixtures, testing was performed to determine properties of whole clay brick and tile, as well as the crushed recycled brick masonry aggregate (RBMA), and a database of material properties was developed.
Findings
Concrete mixtures exhibiting acceptable workability and other fresh concrete properties were obtained, and tests were performed to assess mechanical properties and durability performance of the hardened concrete. Results indicated that recycled brick masonry aggregate concrete (RBMAC) mixtures can exhibit mechanical properties comparable to that of structural‐ and pavement‐grade PCC containing conventional coarse aggregates.
Research limitations/implications
Results for durability performance were mixed, but additional testing to evaluate durability performance is recommended.
Practical implications
Although RBMAC has been untested in field applications, results of laboratory studies performed to date indicate that this material shows promise for use in pavement and structural applications. Future testing of RBMAC in both laboratory and field settings will allow stakeholders to gain a comfort level with its properties, identify specific potential uses, and establish guidelines that will assist in ensuring acceptable service life performance.
Originality/value
From the standpoint of sustainability, use of recycled materials as aggregates provides several advantages. Landfill space used for disposal is decreased, and existing natural aggregate sources are not as quickly depleted. Use of recycled aggregates in lieu of virgin quarried aggregates can potentially result in a lower embodied energy of the concrete, although this is often dependent on hauling costs. This particularly holds true if the methodology used to compute the embodied energy of a structure accounts for the “recovery” of energy at the end of its service life.
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Luciano Castro Lara, Henara Costa and José Daniel Biasoli de Mello
This paper aims to analyse the influence of the thickness of different layers [diamond-like-carbon (DLC) and chromium nitride (CrN)] on the sliding wear behaviour of a…
Abstract
Purpose
This paper aims to analyse the influence of the thickness of different layers [diamond-like-carbon (DLC) and chromium nitride (CrN)] on the sliding wear behaviour of a multifunctional coating on AISI 1020 substrates. When small and cheap components need to be manufactured in large scale, they are often produced using soft metals, such as unhardened low carbon steels and pure iron.
Design/methodology/approach
Two families, one with thicker films and the other with thinner films, were deposited onto a soft carbon steel substrate by plasma-enhanced chemical vapour deposition (PECVD). Reciprocating linear tests with incremental loading assessed the durability of the coatings. In addition, friction coefficient and wear rates of both specimens and counterbodies were measured at a constant load.
Findings
Thinner layers presented lower sliding wear rates (four-five times lower) for both specimens and counterbodies, less spalling and protective tribolayers on the wear tracks.
Originality/value
Although multilayered CrN–DLC coatings on relatively hard substrates such as HSS and cemented carbide tools are already a proven technology, much less is known about its deposition on a much softer substrate such as low carbon steel. In previous works, we have analysed the influence of layer thickness on hardness and scratch resistance of the same coatings. This paper presents results for their performance under wear sliding conditions using an original approach (three-dimensional triboscopic maps) for two distinct configurations (increasing load and constant load).
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Elina Ilén, Farid Elsehrawy, Elina Palovuori and Janne Halme
Solar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is…
Abstract
Purpose
Solar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is prerequisite for the product acceptance of e-textiles, has been rarely examined. This paper aims to report a systematic study of the laundry durability of solar cells embedded in textiles.
Design/methodology/approach
This research included small commercial monocrystalline silicon solar cells which were encapsulated with functional synthetic textile materials using an industrially relevant textile lamination process and found them to reliably endure laundry washing (ISO 6330:2012). The energy harvesting capability of eight textile laminated solar cells was measured after 10–50 cycles of laundry at 40 °C and compared with light transmittance spectroscopy and visual inspection.
Findings
Five of the eight textile solar cell samples fully maintained their efficiency over the 50 laundry cycles, whereas the other three showed a 20%–27% decrease. The cells did not cause any visual damage to the fabric. The result indicates that the textile encapsulated solar cell module provides sufficient protection for the solar cells against water, washing agents and mechanical stress to endure repetitive domestic laundry.
Research limitations/implications
This study used rigid monocrystalline silicon solar cells. Flexible amorphous silicon cells were excluded because of low durability in preliminary tests. Other types of solar cells were not tested.
Originality/value
A review of literature reveals the tendency of researchers to avoid standardized textile washing resistance testing. This study removes the most critical obstacle of textile integrated solar energy harvesting, the washing resistance.
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Jingying Xu, Zimin Jin, Jing Jin, Lei Lei and Jianwei Tao
People have always been invaded by mosquitoes, and the development of new anti-mosquito fabrics has attracted much attention. The purpose of this paper is to study the effect of…
Abstract
Purpose
People have always been invaded by mosquitoes, and the development of new anti-mosquito fabrics has attracted much attention. The purpose of this paper is to study the effect of knitting process on the performance of anti-mosquito seamless fabrics and provide a basis for obtaining anti-mosquito seamless knitted fabrics with excellent comprehensive performance.
Design/methodology/approach
This paper uses bamboo–polyester mosquito repellent yarn containing wormwood extract as the face of seamless knitted fabric. The test factors include ordinary material in the face yarn, ground yarn material, seamless knitted structure and arrangement ratio of ordinary yarn and anti-mosquito yarn in face yarn. According to the quasi-level additional orthogonal test, 12 knitting plans are determined, and the mosquito repellent test and durability test are performed on the fabric.
Findings
The experimental results show that the optimal fabric for anti-mosquito performance is 12#, and the average repellent rate after washing 15 times is 58.57%. The corresponding process is that the face yarn is fully anti-mosquito yarn, the fabric is a single-sided mesh structure and the ground yarn is made of 4.4tex moisture-absorbing nylon/2.2tex spandex wrapped yarn.
Research limitations/implications
In this paper, there is still a lack of diversity in the selection of yarn materials and fabrics. In the follow-up research, the authors will use more fabrics and yarn materials for combination and experimentation and simulate and predict the mosquito resistance rate of knitted fabrics with different materials and structures.
Practical implications
The development of anti-mosquito seamless knitted fabrics with good comprehensive performance and the use of environmentally friendly wormwood repellents not only conform to the current people's healthy and environmentally friendly life philosophy, but also promote the development of the functional seamless knitted fabric market.
Social implications
In addition, seamless knitted fabrics have a huge market prospect, and many of their fabrics are used for sports underwear and outdoor wear. Therefore, the research and development of functional knitted fabrics will attract consumers to buy. While improving the wearing comfort, it can increase profits for the company.
Originality/value
The mosquito-proof functional seamless knitted fabric developed in this research has a high mosquito-proof rate after 15 times and can be used as underwear fabric or outdoor sports fabric.
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Pingping Hou, HongYan Huang, Yong Wang, Jun Zhang and Dewen Sun
The purpose of this study is to prepare a robust superhydrophobic coating on concrete substrate with remarkable chemical and mechanical durability through “all-covalent” strategy.
Abstract
Purpose
The purpose of this study is to prepare a robust superhydrophobic coating on concrete substrate with remarkable chemical and mechanical durability through “all-covalent” strategy.
Design/methodology/approach
Amino-modified silica nano/micro-particles were prepared through two synthetic steps. “All-covalent” strategy was introduced to prepare a robust superhydrophobic coating on concrete surface via a “all-in-one” dispersion and a simple spraying method. The successful construction of the products was confirmed by Fourier transform infrared spectroscopy, water contact angles (WCA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The concrete protective properties were verified by solution immersion test, pull-off test and rapid chloride migration coefficient test. The mechanical durability was tested by falling sand impact.
Findings
Hierarchical structures combined with the low-surface-energy segments lead to typically superhydrophobic coating with a WCA of 156° and a sliding angle of 1.3°. The superhydrophobic coating prepared through “all-covalent” strategy not only improves chemical and mechanical durability but also achieves higher corrosion and wear resistance than the comparison sample prepared by physically blending strategy. More importantly, the robust superhydrophobic coating showed excellent adhesion and protective performance of concrete engineerings.
Practical implications
This new “all-covalent” superhydrophobic coating could be applied as a concrete protective layer with properties of self-cleaning, anti-graffiti, etc.
Originality/value
Introduction of both silica nanoparticles and silica microparticles to prepare a robust superhydrophobic coating on concrete surface through “all-covalent” strategy has not been systematically studied previously.
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