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1 – 10 of over 3000Introduction The electron microscope and electron microprobe analyser are two of the newest and most advanced instruments available for corrosion and oxidation research…
Abstract
Introduction The electron microscope and electron microprobe analyser are two of the newest and most advanced instruments available for corrosion and oxidation research. Metallographic techniques with a light microscope are very limited for the typically rough surfaces of corroded metal, and even a simple brown rust spot (Fig. 1a) takes on a new character when viewed with a scanning electron microscope (SEM), Fig. 1b. The depth of focus is at least three hundred times better than the light microscope, which makes the SEM very suitable for examining the surface topography of worn surfaces, fatigue fractures, hydrogen embrittled specimens, stress corroded materials or high temperature oxidation products. Normally, as the materials are conducting, the only preparation needed is to stick the piece of corroded metal on to a stub with conducting paint. Where specimens are too large to put into the microscope's vacuum system, a positive replica of the surface may be used instead.
A RECENT meeting of the Society of Automotive Engineers at St. Louis reviewed operations of Diesel Engines in Industry and opened with a presentation of technical papers outlining…
Abstract
A RECENT meeting of the Society of Automotive Engineers at St. Louis reviewed operations of Diesel Engines in Industry and opened with a presentation of technical papers outlining progress in the use of the spectrograph and electron microscope for studying the condition of new and used oils, particularly additive containing oils. Three papers were presented as follows :—“An Electron looks at Detergent Oils” by John L. Broughten of the Union Oil Co., California; “Diesel Maintenance Control by Spectrographic Means” by H. R. Sennstrom (Research and Testing Engineer of American Locomotive Company); “Practical Use of the Spectrograph and Electron Microscope for Study of Diesel Engine Conditions” by Ray McBrian and L. C. Atchison, both of the Denver & Rio Grande Western Railroad Co. The following are the main points made in these papers.
J.A. von Fraunhofer and G.A. Pickup
In the previous two articles the emphasis was on wet and electrochemical techniques, with particular reference to the potentiostat. The physical examination of corrosion products…
Abstract
In the previous two articles the emphasis was on wet and electrochemical techniques, with particular reference to the potentiostat. The physical examination of corrosion products is of equal importance, especially, for example, in the study of oxidation by dry gases at elevated temperatures where electrochemical studies are not normally feasible. In this article the application of physical techniques to corrosion studies will be discussed.
First January 1973 will not only mark the beginning of a New Year but a year which history will mark as a truly momentous one, for this is the year that Britain, after centuries…
Abstract
First January 1973 will not only mark the beginning of a New Year but a year which history will mark as a truly momentous one, for this is the year that Britain, after centuries of absence, re‐enters the framework of Europe as one of the Member‐States of the enlarged European Community. This in itself must make for change on both sides; Britain is so different in outlook from the others, something they too realize and see as an acquisition of strength. There have been other and more limited forms of Continental union, mainly of sovereignty and royal descent. Large regions of France were for centuries under the English Crown and long after they were finally lost, the fleur de lis stayed on the royal coat of arms, until the Treaty of Amiens 1802, when Britain retired behind her sea curtain. The other Continental union was, of course, with Hanover; from here the Germanized descendants of the Stuarts on the female line returned to the throne of their ancestors. This union lasted until 1832 when rules of descent prevented a woman from reigning in Hanover. It is interesting to speculate how different history might have been if only the British Crown and the profits of Tudor and Stuart rule had been maintained in one part of central Europe. However, Britain disentangled herself and built up overwhelming sea power against a largely hostile Europe, of which it was never conceived she could ever be a part, but the wheel of chance turns half‐circle and now, this New Year, she enters into and is bound to a European Community by the Treaty of Rome with ties far stronger, the product of new politico‐economic structures evolved from necessity; in a union which cannot fail to change the whole course of history, especially for this country.
Rania Abdel Gwad Eloriby and Hamdy Mohamed Mohamed
This study aims to assess the efficacy of nano-alumina (nano-Al2O3) in improving the performance of epoxy adhesives used to assemble archaeological glass. The conservators face a…
Abstract
Purpose
This study aims to assess the efficacy of nano-alumina (nano-Al2O3) in improving the performance of epoxy adhesives used to assemble archaeological glass. The conservators face a significant problem in assembling this type of artifact. Therefore, the assembling process is considered one of the important stages that must be taken care of to preserve these artifacts from damage and loss.
Design/methodology/approach
To evaluate the stability of adhesives, the samples were subjected to artificial aging under varying environmental conditions. Some investigative techniques and mechanical testing were used in this study to evaluate the selected materials. It includes a transmission electron microscope, X-ray diffraction, visual assessment, digital microscope, scanning electron microscopy (SEM), color change and tensile strength test.
Findings
The visual evaluation and the digital microscope results showed that the epoxy/nano-Al2O3 greatly resisted artificial aging. Although slight yellowing was present, it did not significantly affect the general appearance of the samples. On the other hand, the pure epoxy sample showed cracks of different sizes on its surface due to aging, as evidenced by SEM examination. Furthermore, epoxy/nano-Al2O3 has a better tensile strength (11.27 MPa) and slight color change (ΔE = 2.06).
Originality/value
The main objective of the experimental study was to identify appropriate adhesive materials that possess key properties such as non-yellowing and improved tensile strength by conducting various tests and evaluations. Ultimately, the goal was to identify materials that could serve as effective adhesives for assembling the archaeological glass.
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Fawzia Fahim Abdel-Mohsen and Hassan Salah Aly Emira
– The purpose of this study was to prepare colour pigments for use as spectrally selective coatings for solar absorbers.
Abstract
Purpose
The purpose of this study was to prepare colour pigments for use as spectrally selective coatings for solar absorbers.
Design/methodology/approach
Nano-particles cobalt and nickel oxides were prepared by sol–gel techniques. These oxides were prepared with its molar ratios and annealed at 200, 400, 600 and 800°C. The structure of the pigments was characterized by infrared spectrometer, differential scanning calorimetry analysis, X-ray diffraction, transmission electron microscope and scanning electron microscope.
Findings
Encapsulated cobalt and nickel oxides were completely formed at 800 and 600°C, and its colour was black and dark green, respectively. The results confirmed that black and green pigments combined selectivity with colour. Optical properties such as absorption and reflection were affected by the firing temperatures on cobalt and nickel oxides–gel polymers. All synthesized pigments consisted of nano-particles.
Research limitations/implications
The prepared samples used in the present work were synthesized from cobalt chloride and nickel acetate. The salts were dispersed in polyacrylamide as a precursor.
Practical implications
The prepared metal oxides had good solar properties.
Originality/value
Colour becomes more important for thermal solar collectors, and it has attracted interest. This might be related to a generally growing attention towards architectural integration of solar energy systems into building. Architects would prefer different colours besides black, even if lower efficiency would have to be accepted.
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Abstract
Purpose
To study the effect of Ag content on the melting temperature and wetting properties of Sn‐8.5Zn‐xAg‐0.01Al‐0.1Ga lead‐free Solders.
Design/methodology/approach
The solder alloys used in the experiment were Sn‐8.5Zn‐xAg‐0.01Al‐0.1Ga (x=0, 0.1, 0.3, 0.5, 1 and 1.5). In this study, the alloys were initially studied using differential scanning calorimetry to determine their melting temperatures. Afterward, the solderability of the solders was studied using wetting balance and contact angle methods. Moreover, the microstructures of the solders were also investigated with an optical microscope, scanning electron microscope, energy dispersive X‐ray, X‐ray diffraction and electron probe micro analysis.
Findings
A small increase in Ag content in the Sn‐8.5Zn‐xAg‐0.01Al‐0.1Ga solders, from 0.1 to 1.0 wt%, has been found to lower their solidus temperature from 198.05°C to 190.20°C. A Ag content of 1.5 wt% increased the solidus temperature of the studied solder systems to 197.79°C. Furthermore, the study also found that the addition of silver lowered the wetting forces of the studied solders. The formation of multi‐intermetallic layers of Cu‐Zn and Ag‐Zn at the interface between the studied solders and copper might explain the reduction of the wetting forces.
Research limitations/implications
The silver contents in the studied Sn‐8.5Zn‐xAg‐0.01Al‐0.1Ga solders were limited to 0, 0.1, 0.3, 0.5, 1.0 and 1.5 wt%.
Practical implications
Useful literature for solder alloy designers and SMT engineers.
Originality/value
The paper provides the answers to the research question of what is the effect of silver content on the melting temperature and wetting properties of Sn‐8.5Zn‐xAg‐0.01Al‐0.1Ga solders.
Benjamin Tawiah, Liping Zhang, Anli Tian and Shai Shao Fu
The purpose of this paper is to colour aluminium pigment to the highest chroma using SiO2 and organic silane with dichlorotriazine reactive dye and investigate its reaction…
Abstract
Purpose
The purpose of this paper is to colour aluminium pigment to the highest chroma using SiO2 and organic silane with dichlorotriazine reactive dye and investigate its reaction mechanism, chemical stability and thermal properties to improve its applicability in surface coatings.
Design/methodology/approach
Aluminium pigment was encapsulated by the catalysed sol-gel method using SiO2, followed by modification with γ-glycidoxypropyltrimethoxysilane (GPTMS). Purified reactive dye (1-Amino-4-[3-(4,6-dichlorotriazin-2-ylamino)-4-sulfophenylamino]anthraquinone-2-sulfonic acid (X-BR)) was covalently immobilized onto modified SiO2 to obtain coloured aluminium pigment. The reaction mechanism, chemical stability and thermophysical properties were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope and thermogravimetric analyses (TGA).
Findings
The results showed that X-BR was covalently attached to modified Al/SiO2 with maximum colour grafting of 95 per cent when the dosage of GPTMS and X-BR per weight of modified Al/SiO2 was 25 and 15 per cent, respectively, at pH 8.5 and a temperature of 40°C. The coloured aluminium pigment had good chemical stability with excellent anti-migration properties in many solvents.
Research limitations/implications
The organic silane used required a careful control of pH to ensure maximum colour grafting efficiency meanwhile other silanes with amine groups could also be used effectively with different kinds of colorants besides reactive dyes.
Practical implications
The method used is less cumbersome and provides a simple route to preparing coloured aluminium pigment.
Originality/value
The use of organic-inorganic SiO2/γ- GPTMS with purified reactive dye to covalently colour aluminium pigment to the highest chroma is novel and will help advance the frontiers of knowledge on coloration of aluminium pigments.
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Reza Shoja Razavi, Gholam Reza Gordani and H.C. Man
The purpose of this paper is to consider the corrosion properties of laser nitrided Ti‐6Al‐4V alloys that have been reported previously by several researchers.
Abstract
Purpose
The purpose of this paper is to consider the corrosion properties of laser nitrided Ti‐6Al‐4V alloys that have been reported previously by several researchers.
Design/methodology/approach
Different kinds of surface nitriding methods of titanium alloys, such as plasma nitriding, ion nitriding, gas and laser nitriding, are introduced. Microstructure changes, such as phase formation and the influence of laser processing parameters in laser nitriding layers of Ti‐6Al‐4V alloys, were investigated using scanning electron microscope, transmission electron microscope, X‐ray photo‐electron spectroscopy, and X‐ray diffraction. Based on investigations presented in the literature, the effect of laser nitriding on the corrosion behavior of Ti‐6Al‐4V alloy was reviewed.
Findings
By regulating the laser processing parameter, the microstructure of the nitrided layer can be controlled to optimize corrosion properties. This layer improves corrosion behavior in most environments, due to the formation of a continuous TiNxOy passive film, which can retard the ingress of corrosive ions into the substrate and can maintain a constant value of a current density. Therefore, the laser gas nitrided specimens have a relatively noble corrosion potential and a very small corrosion current, as compared to untreated specimens.
Originality/value
This paper comprises a critical review, and its collection of references is useful. It summarizes current knowledge in laser surface treatment research.
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Yi Xin, Zijiang Jiang, Wenwen Li, Zonghao Huang and Cheng Wang
This paper aimed to prepare a kind of ZnS nanoparticles/poly(phenylene vinylene) (PPV) nanofibre and investigate its properties. Because the ZnS nanoparticles are important…
Abstract
Purpose
This paper aimed to prepare a kind of ZnS nanoparticles/poly(phenylene vinylene) (PPV) nanofibre and investigate its properties. Because the ZnS nanoparticles are important optoelectronic materials, their incorporation into one-dimensional (1D) nanoscale polymer matrices should be a meaningful subject for electrospinning.
Design/methodology/approach
ZnS/PPV composite nanofibres with an average diameter of 600 nm were successfully prepared by a combination of the in situ method and electrospinning technique. The nanofibres were electrospun from Zn(CH3COO)2·2H2O and PPV precursor composite solution, and the ZnS/PPV fibres were obtained by exposure of the electrospun fibres to H2S gas to prepare ZnS nanoparticles in situ. Such fibres were characterised using X-ray Diffraction (XRD), Fourier transform infrared, transmission electron microscope (TEM), scanning electron microscope and photoluminescence (PL). The photoelectric properties of the fibres obtained were also investigated.
Findings
XRD patterns proved that ZnS nanocrystals generated in the composite nanofibres. The TEM image showed that the nanocrystals were homogeneously dispersed in the nanofibres. The PL spectrum of ZnS/PPV composite nanofibres exhibited a blue shift relative to the PPV nanofibres. I-V curve of the single nanofibre device under 5.76 mW/cm2 light illumination showed that the composite nanofibres have good photoelectric properties.
Research limitations/implications
The comparisons of advantages between ZnS/PPV nanofibres with similar nanofibres will be further expanded in a later research.
Practical implications
Results demonstrate the promise of these novel nanostructures as ultraminiature photodetectors with the potential for integration into future hybrid nanophotonic devices and systems.
Originality/value
The integration of inorganic semiconductor nanoparticles into organic conjugated polymers leads to composite materials with unique physical properties and important application potential. In this work, ZnS nanoparticles were introduced into PPV by an in situ method, so as to obtain a kind of novel 1D nanomaterials with good photoelectric properties.
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