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Article
Publication date: 8 February 2016

Mathias Linz, Franz Walzhofer, Stefan Krenn, Andreas Steiger-Thirsfeld, Johannes Bernardi, Horst Winkelmann and Ewald Badisch

The purpose of this paper is to investigate the driving mechanisms for crack propagation regarding the related microstructures. Cracks in white etching layers have been…

Abstract

Purpose

The purpose of this paper is to investigate the driving mechanisms for crack propagation regarding the related microstructures. Cracks in white etching layers have been found at the surface of submerged steel blades subjected to frictional sliding conditions.

Design/methodology/approach

In-situ monitoring revealed a fluctuation between mixed lubrication and hydrodynamic lubrication conditions. One lamella including a crack tip was prepared for transmission electron microscopy (TEM) using focused ion beam milling. Transmission electron microscope analysis was performed with the aim to understand the characteristics of the crack propagation, especially considering the influence of the microstructural configuration (grain refinement, carbides, martensite and ferrite grains).

Findings

The investigations have shown a grain-refined plastically deformed layer (friction martensite with grain sizes of < 100 nm) which influences the propagation direction of cracks introduced at the frictionally stressed surface. Thereby, the crack propagation is dominantly parallel to the margin of the grain-refined martensitic layer at the surface and the base material. Cracks were split into side cracks what mostly appears at present carbides. In this case, the crack propagation might strike through the carbide or separate it from the matrix due to the mechanical misfit.

Originality/value

For obtaining the results of this paper, a very special preparation of tribologically stressed samples was performed. Accordingly, specific findings of the crack propagation behavior under such conditions were achieved and are documented in the presented work. Moreover, the described crack propagation process is a combination of several mechanisms which occur in very limited region underneath the surface and are investigated by high-resolution TEM.

Details

Industrial Lubrication and Tribology, vol. 68 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 February 2013

Xin Luo, Wenhui Du, Xiuzhen Lu, Toshikazu Yamaguchi, Gavin Jackson, Li lei Ye and Johan Liu

The composition and thickness of surface oxide of solder particles is extremely important to the quality of interconnect and reliability of packaged system. The purpose of…

Abstract

Purpose

The composition and thickness of surface oxide of solder particles is extremely important to the quality of interconnect and reliability of packaged system. The purpose of this paper is to develop an observable measurement to research the issue.

Design/methodology/approach

AES (Auger electron spectroscopy), XPS (X‐ray photoelectron spectroscopy), TEM (transmission electron microscopy) and STEM (scanning transmission electron microscopy) were employed to examine the oxide layer on microscale solder powders. Conventional techniques and FIB (Focus Ion Beam) were employed for the TEM sample preparation. High angle annular dark field (HAADF) pattern was applied to distinguish the oxide layer and the solder matrix by the contrast of average atomic number. The results were confirmed by AES and XPS measurement.

Findings

The solder powders were exposed to air (70% relative humidity) at 150°C for 0, 120 and 240 h for the accelerated growth of oxide. The surface oxide thickness was 6 nm and 50 nm measured by TEM for 0 h and 120 h samples, respectively. It was found that the increase in surface oxide thickness of solder particles is proportional to the rooting of time. The elemental distribution along the oxide was quantified by line scanning using STEM and the atomic ratio of Sn to O in the oxide layer nearer to the outer, the middle, and the inner (adjacent to the solder matrix) was found to be 1:2, 2:3 and 1:1, respectively. The result was validated using XPS which gave Sn to O ratio of 1:2 at 5 nm depth of surface oxide.

Originality/value

This is the first time FIB technology has been used to prepare TEM specimens for solder particles and TEM pictures shown of their surface oxide layer. Though requiring more care in sample preparation, the measurements by TEM and STEM are believed to be more direct and precise.

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Article
Publication date: 1 February 1990

C.D. Qin and B. Derby

The strength of annealed ZrO2/Pd diffusion bonds was found to be weakened after annealing in both air and vacuum. Annealing in air reduces the strength much faster and…

Abstract

The strength of annealed ZrO2/Pd diffusion bonds was found to be weakened after annealing in both air and vacuum. Annealing in air reduces the strength much faster and more severely than in vacuum. Fracture surfaces of as‐bonded joints and those annealed in air and vacuum were studied to characterise the different effects of air and vacuum on the bonded interfaces. Various sizes of precipitates and voids were observed and their distribution on the fractured surfaces was examined by light microscopy. Large precipitates and voids were found close to the edges of the specimen. It is believed that the loss of strength after annealing is an effect of these defects at the highly stressed specimen edges. Transmission and analytical electron microscopy of as‐bonded joints show that an interface layer of very fine grains about 1 micron thick was formed during the bonding process. This layer has a different crystalline structure and composition from both Pd and ZrO2. Characterisation of this layer by electron microscopy is presented in this report. The formation of such a thick interface layer is probably not a pure diffusion process, rather a diffusion and melting process. From the Pd‐Zr phase diagram, there is a range of compositions near a eutectic point where a liquid phase is possible at the bonding temperatures used (1100°C). Taking the Pd‐Zr system as a qualitatively comparable system to Pd‐ZrO2, it is deduced that, at the very beginning of the bonding, Zr and Pd diffuse into each other until the melting composition is reached. The formation of the liquid phase will promote the contact and bonding processes dramatically. This explains why strong bonding cannot be achieved at lower bonding temperatures as was reported in an earlier paper. Similar experiments on Ni/ZrO2 diffusion bonds have also been studied to identify the mechanism of bonding and to compare it with Pd/ZrO2. No reaction was observed at the interface in Ni/ZrO2. Thus the wetting mechanism is absent which explains the formation of a large amount of interface voids and the much weaker bonding strength found in Ni/ZrO2 bonds.

Details

Microelectronics International, vol. 7 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 14 June 2013

Mieczysław Kaczorowski and Radosław Winiczenko

The results of a study of friction welding of ductile cast iron using stainless steel interlayer are presented. Based on the microstructure evolution at the region close…

Abstract

Purpose

The results of a study of friction welding of ductile cast iron using stainless steel interlayer are presented. Based on the microstructure evolution at the region close to the ductile cast iron‐stainless steel interface, the phenomena accompanying the process of joining were evaluated. Therefore, the purpose of this paper is to take a closer look into metallurgical phenomena accompanying the friction welding of ductile cast iron.

Design/methodology/approach

In this paper, ductile cast iron and austenitic‐stainless steel are welded using the friction welding method. The tensile strength of the joints was determined using a conventional tensile test machine. Moreover, the hardness across the interface ductile cast iron‐stainless steel interface was measured on a metallographic specimen. The microstructure of the joints was examined using light metallography as well as electron microscopy. In this case, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied. Energy Dispersive X‐ray analysis (EDS) was carried out across the section of friction welded ductile iron‐stainless steel interface.

Findings

On the basis of careful analysis of experimental data it was concluded that the process of friction welding was accompanied with diffusion of Cr, Ni and C atoms across the ductile cast iron‐stainless steel interface. This leads to an increase of carbon concentration in stainless steel where chromium carbides were formed, the size and distribution of which was dependent on the distance from the interface.

Originality/value

The main value of this paper is to contribute to the literature on friction welding of ductile cast iron.

Details

Industrial Lubrication and Tribology, vol. 65 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 6 April 2020

Maryam Khashij, Arash Dalvand, Mohammad Mehralian, Ali Asghar Ebrahimi and Rasoul Khosravi

The purpose of this paper is to analyze zero valent iron nanoparticles (NZVIs) by a novel green method, taken from Thymus vulgaris (TV) plant extract, were synthesized and…

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Abstract

Purpose

The purpose of this paper is to analyze zero valent iron nanoparticles (NZVIs) by a novel green method, taken from Thymus vulgaris (TV) plant extract, were synthesized and applied to degrade reactive black 5 (RB5) azo dye.

Design/methodology/approach

The optimum conditions for the highest removal of RB5 dye were determined. Characterization of NZVIs was done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The NZVIs were used for the removal of dye RB5, and the parameters affecting were discussed like pH, initial concentration, contact time and NZVIs dosage.

Findings

The characterization results of NZVIs by SEM, TEM, FTIR and XRD show that polyphenols, organic acids and proteins reduce not only the green synthesis of NZVIs but also the aggregation of nanoparticles. The maximum dye removal efficiency of 99.6 per cent occurred at pH 4, NZVIs dose of 600 mg/L, and contact time of 5 min. The adsorption of RB5 dye onto the NZVIs surface and scavenging of the azo bond (−N = N) by the strong reduction of NZVIs were the proposed mechanisms for dye removal. The application of NZVIs to treat wastewater containing reactive dye shows high degradation efficiency.

Research limitations/implications

The findings may greatly benefit the application of the NZVIs taken from Thymus vulgaris (TV) in the fields of dye adsorption.

Practical implications

The present study is novel because it incorporated the morphological and structural properties of the synthesized NZVIs using a native plant of Iran and studied the capability of green-synthesized NZVIs to remove RB5 as a water contaminant.

Social implications

The native plant presented here can be developed for reduced environmental pollution before discharge to accepted water.

Originality/value

The NZVIs is prepared via green-synthesized method, which is prepared with leaves of TV. There are two main innovations. One is that the novel NZVIs is prepared successfully by native plant via green-synthesized method. The other is that the optimized conditions were obtained for the removal of RB5 dye as a water contaminant. Furthermore, to the best of our knowledge, no study has ever investigated the removal of RB5 by NZVIs produced using a native plant in Iran.

Details

Pigment & Resin Technology, vol. 49 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Content available
Article
Publication date: 2 August 2019

Maria de Lourdes Miranda-Medina, Christian Tomastik, Tia Truglas, Heiko Groiss and Martin Jech

The purpose of this paper is to provide a general picture for describing the formed tribofilm, including chemical and physical aspects in the micro-scale and the…

Abstract

Purpose

The purpose of this paper is to provide a general picture for describing the formed tribofilm, including chemical and physical aspects in the micro-scale and the nano-scale. In a previous study, the durability of zinc dialkyl dithiophosphate (ZDDP) tribofilms on cylinder liner samples has been investigated in a tribometer model system by using fresh and aged fully formulated oils and replacing them with PAO8 without additives. Analyses of the derived tribofilms by means of X-ray photoelectron spectroscopy and scanning electron microscopy could give some hints about the underlying mechanisms of the tribofilm build-up and wear performance, but a final model has not been achieved.

Design/methodology/approach

Thus, characterisation of these tribofilms by means of focused ion beam-transmission electron microscopy (FIB-TEM) and energy dispersive X-ray spectroscopy is presented and a concluding model of the underlying mechanisms of tribofilm build-up is discussed in this paper.

Findings

For tribotests running first with fresh fully formulated engine oil, a rather homogeneous ZDDP-like tribofilm is found underneath a carbon rich tribofilm after changing to non-additivated PAO8. However, when the tests run first with aged fully formulated engine oil, no ZDDP-like tribofilm has been found after changing to non-additivated PAO8, but a wear protective carbon rich tribofilm.

Originality/value

The obtained results provide insights into the structure and durability of tribofilms. Carbon-based tribofilms are built up on the basis of non-additivated PAO8 because of the previously present ZDDP tribofilms, which suggests an alternative way to reducing the consumption of antiwear additives.

Details

Industrial Lubrication and Tribology, vol. 72 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 1 July 1988

Lalgudi V. Ramanathan

The examination of products of aqueous and non aqueous corrosion is carried out to obtain information about one of a combination of aspects such as composition, hardness…

Abstract

The examination of products of aqueous and non aqueous corrosion is carried out to obtain information about one of a combination of aspects such as composition, hardness, stress level, adhesion to basis metal and other mechanical properties (figure 1). A number of techniques are avialable to investigate corrosion products and some of these techniques have found greater application with products of aqueous corrosion and some with products of gaseous corrosion. This paper presents the technqiues available for obtaining information about the various aspects mentioned above and discusses the main characteristics, nature of data obtainable, advantages and limitations of some of the less know techniques.

Details

Anti-Corrosion Methods and Materials, vol. 35 no. 7
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 3 May 2016

Zhiwei Li

The purpose of this paper is to seek a surfactant or template-free, simple and green method to fabricate NiO nanobelts and to find an effective technique to detect the…

Abstract

Purpose

The purpose of this paper is to seek a surfactant or template-free, simple and green method to fabricate NiO nanobelts and to find an effective technique to detect the ethanol vapor at room temperature.

Design/methodology/approach

NiO nanobelts with high aspect ratio and dispersive distribution have been synthesized by a template-free hydrothermal reaction at 160°C for 12 h. The products are studied by X-ray diffraction (XRD), energy dispersive spectroscopY, scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, selective area electron diffractio and X-ray photoelectron spectroscopy. In particular, the room-temperature ethanol sensitivity of NiO nanobelts is investigated by the surface photo voltage (SPV) technique.

Findings

The prepared NiO nanobelts is single crystalline bunsenite structure with the length of approximately 10 μm and the diameter of approximately 30 nm. The atomic ratio of “Ni” to “O” is 0.92:1. When the concentration of ethanol vapor reaches 100 ppm, the sensitivity of NiO nanobelts is 7, which can meet the commercial demanding of ethanol gas sensor.

Originality/value

The NiO nanobelts can be obtained by a template-free, simple and green hydrothermal reaction at 160°C for 12 h. The NiO nanobelts-based gas sensor is a promising candidate for the application in ethanol monitoring at room temperature by SPV technique.

Details

Microelectronics International, vol. 33 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 July 1973

Anita Fursey

Introduction 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.

Details

Anti-Corrosion Methods and Materials, vol. 20 no. 7
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 12 January 2010

Nivin M. Ahmed and Mohamed M. Selim

The purpose of this paper is to introduce a new method of pigment preparation, which is economic and highly efficient in corrosion protection properties, known as the…

Abstract

Purpose

The purpose of this paper is to introduce a new method of pigment preparation, which is economic and highly efficient in corrosion protection properties, known as the core‐shell method. According to this method, a cheap core (an extender) is covered with only a surface layer of effective pigments. Following this method of preparation, a new group of pigments is prepared in this research using the Egyptian kaolin ore as the core covered with single and mixed zinc, magnesium, and zinc‐magnesium phosphates as a shell to replace the original phosphates. These new pigments combine the properties of both its core and shell counter‐parts exhibiting improved corrosion protection properties that exceed both of kaolin and zinc phosphate individually.

Design/methodology/approach

Pigments concerned in this paper are prepared using simple chemical techniques, and then they are characterised using X‐ray diffraction, scanning electron microscopy combined with energy‐dispersive X‐ray analysis, and transmission electron microscopy. These pigments are incorporated in solvent‐based paint formulations based on medium oil alkyd resin. The physico‐mechanical properties of dry films and their corrosion properties are tested using accelerated laboratory test in 3.5 percent NaCl for 28 days, according to ASTM.

Findings

The prepared kaolin‐phosphate (core‐shell) pigments are based essentially on Egyptian kaolin ore, which is an abundant cheap ore in Egypt, and then the kaolin is covered with a surface layer of phosphates that are proved to be efficient anticorrosive pigments. These pigments are easily prepared, economically feasible and can successfully replace ordinary phosphate pigments with superior corrosion protection behaviour.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent.

Originality/value

Prepared pigments are environmentally friendly and can replace hazardous pigments (e.g. chromates) and ordinary phosphates. The main advantages of these pigments are that they combine both the properties of their core and shell counter‐parts, and they are of lower cost with similar and maybe in some cases better efficiency in corrosion protection of metals. Also, they can be applied in industries other than paints, e.g. paper, rubber and plastics composites.

Details

Pigment & Resin Technology, vol. 39 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

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