Scanning Electron Microscopy And Energy Dispersive Spectroscopy Research Articles

Electrochemical Extraction of Holmium and Thermodynamic Properties of Ho-Bi Alloys in LiCl-KCl Eutectic

The electrochemical reduction of Ho (III) on W electrode and liquid Bi film electrode was investigated in LiCl-KCl eutectic by various electrochemical techniques. The reduction reaction of Ho (III) was found to be diffusion-controlled process with three electrons exchanged, which was considered as quasi-reversible. The diffusion coefficient of Ho (III) was determined by cyclic voltammetry and chronopotentiometry. The results of cyclic voltammetry and square wave voltammetry obtained on Bi film electrode exhibited two new reduction peaks at less negative potential than that on W electrode due to the formation of different Ho-Bi intermetallic compounds. Furthermore, the thermodynamic properties on the formation of Ho-Bi intermetallic compounds were measured using open circuit chronopotentiometry in the temperature range from 773 K to 863 K. The electroextraction of holmium was performed on liquid Bi electrode by potentiostatic and galvanostatic electrolysis. The extractive products were characterized by scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD). It was showed that Ho-Bi alloys consisted of HoBi and Bi phases. The concentration of Ho (III) was monitored by square wave voltammetry and analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES). The calibration curve was obtained on linear relationship of peak currents and concentration of Ho (III). Meanwhile, the extraction efficiencies were calculated by ICP-AES and calibration curve, respectively, the highest extraction efficiency could reach 95.9% by potenostatic electrolysis at −1.6 V for 27 h.

Influence of Calcium Chloride Addition on Coal-Based Reduction Roasting of Low-Nickel Garnierite Ore

This work investigates the influence of calcium chloride addition on coal-based reduction roasting low-nickel garnierite ore, and which is most evident in nickel enrichment and ferronickel particles aggregation. The results demonstrate that a concentrate with 11.83% nickel, corresponding to a nickel recovery of 97.38%, was obtained when the ore was reduced at 1150℃ for 40 min in the presence of 12 mass% CaCl2·2H2O, followed by magnetic separation at 250 mT. Compared with the ore reduced without calcium chloride, the nickel enrichment ratio of the concentrate was increased from 3 to 14 by the addition of 12 mass% CaCl2·2H2O. Duing to the vaporization of the nickel chloride formed and the emergence of a new reactive surface, the addition of calcium chloride makes NiO in the garnierite easier to be reduced. The X-ray diffraction and scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) studies show that metallic nickel was mainly enriched into a kamacite phase, and the presence of CaCl2·2H2O significantly accelerated the aggregation and growth of ferronickel particles, attributing to the vaporization and precipitation of nickel chloride on carbon surface together with ferrou chloride.

Microstructure, tensile properties and wear resistance correlations on directionally solidified Al-Sn-(Cu; Si) alloys

The development of alloys suitable for engine bearings demands not only reducing the amount of wear as well as increasing the load carrying capability due to both engines stop/start systems and sudden rise in load or velocity. Al-Sn based alloys are well-known for having excellent tribological and mechanical properties fulfilling these requirements: Sn is a self-lubricating component and addition of third elements should increase the strength of the Al-rich matrix. The current study focuses on interrelations of microstructure of directionally solidified Al-Sn(Cu; Si) alloys and mechanical/tribological properties. In order to analyze the influence of alloy Sn content on the tribological behavior of these ternary alloys, ball-on-disc wear tests were performed under dry sliding conditions. Correlations between tensile strength, elongation and wear volume and the primary dendritic arm spacing (λ1) have been determined. The worn samples were analyzed by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and the wear scar topographies by a confocal profilometer. The analysis of the worn surfaces revealed a change from abrasive to adhesive wear mechanism for Al-Sn-Cu alloys and only adhesive one for Al-Sn-Si alloys. For Al-Sn-Cu alloys, the best wear resistance was observed to be related to coarser microstructures whereas refined microstructures improved the tensile properties, indicating an inverse trend between tensile and tribological properties. The wear resistance of the Al-Sn-Si alloys were shown not to be affected by the size of λ1, however the tensile strength is shown to increase significantly with the decrease in λ1.

Effect of Ni content on the microstructure, thermal properties, and morphology of Ni-SiC composites produced by mechanical alloying

A mixture of nickel (Ni) and silicon carbide (SiC) powder with increasing Ni content (30%, 50%, 70% and 80%) was processed with a planetary mill to obtain a composite material capable of reducing wear and corrosion by thermal spraying. The obtained material was analyzed using scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) to determine its morphology, particle size and elemental composition. Additionally, X-ray diffraction (XRD) was employed for crystallographic analysis, and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to determine whether new phases were formed during the milling process. It was found that samples with a high nickel percentage (i.e., 70% and 80%) possessed spherical particle morphology, which is ideal for improving the fluidity of the material for use in thermal spraying.

Experimental meso scale study on the distribution and evolution of methane adsorption in coal

To reveal the nature of methane storage in coal under different adsorption pressures, a method combining scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) with infrared thermal imaging is used to observe meso structures, methane distribution, and evolution characteristics in coal. The results indicate that the different meso structures of coal have different methane adsorption characteristics, leading to a non-uniformity of the methane distribution and evolution. In other words, compared with the cavity pores and meso fractures in telocollinite, which are compactly filled with clay minerals, the cell cavity pores and meso fractures in telinite, which are non-compactly filled with clay minerals, have more inter-gravel pores and broken coal structures at different scales, and can store great amounts of methane owing to a larger surface area and greater number of adsorption sites for methane molecules. Therefore, the methane content in coal increases sharply in these meso structures with increasing adsorption pressure, resulting in a centralization of the adsorption locations and increasing inhomogeneity of methane storage at different locations. In addition, owing to the shallower potential wells for methane adsorption, the coverage rate of the adsorption sites in these meso structures increases more slowly during an increase in pressure, leading to a decreased aggregation of methane storage in coal.

Interactions between the Ionic Liquid and the ZrO2 Support in Supported Ionic Liquid Membranes for CO2 Separation

This work reports the interaction study of two supported ionic liquid membranes (SILMs) based on 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), which were impregnated into porous zirconia supports with 20 nm average pore diameters. The interaction of ionic liquid-support observed from diffuse reflectance (DR), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) is reported. The IR spectrum in the 600 to 4000 cm−1 range showed a specific interaction of the ionic liquid with the support. The N2 and CO2 permeances in the SILMs with [C4mim][BF4] were 8.7 × 10−8 mol·s−1·m−2·Pa−1 and 9.6 × 10−7 mol·s−1·m−2·Pa−1, respectively. The separation factor through the ionic liquid in the membrane as a function of temperature showed that the SILMs studied here can be used for CO2 separation at low temperatures.

Fire in the Early Palaeolithic: Evidence from burnt small mammal bones at Cueva Negra del Estrecho del Río Quípar, Murcia, Spain

The development of pyrotechnology is a hallmark of human history, providing our ancestors with warmth, security and cooked food. Evidence for fire use before 400 thousand years ago (kya) remains contentious due largely to the taphonomically fragile nature of charcoal and ash. As such, it is imperative to the study of prehistoric fire that we develop techniques and methodologies for identifying anthropogenic fire use via more robust materials. A new methodology described by Fernández-Jalvo and Avery (2015) based on small mammal taphonomy to identify high intensity fire events from the distant past is replicated herein. When we applied this method to assemblages from Cueva Negra del Estrecho del Río Quípar, an upland rock-shelter in southeastern Spain, dated to between 780kya and 980kya, we recognized a spatial relationship between highly heat modified micromammal specimens and a previously reported delineated feature of thermally altered and carbonate rich sediment which also includes heat-fractured chert and calcined bone (the fire feature). The proportion of heavily heat-modified specimens (charred and/or calcined specimens) identified within the stratigraphic context associated with the fire feature proved statistically significant (x2=169.18, p<0.001) when compared with the proportion of similarly modified specimens from overlying deposits (within other stratigraphic layers). The degree of discolouration seen on the micromammal remains within the fire feature has been linked to temperatures exceeding 600°C (Shipman et al., 1984), and as such supports claims that the fire feature may have an anthropogenic origin. Environmental scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) of bone specimens confirms that this discolouration is due to burning rather than post-depositional mineral staining. This confirms that methodology, which represents a novel line of evidence for identifying pyrotechnical events at early Palaeolithic sites, can be used to identify potentially anthropogenic fire events from the distant past when alternative scenarios are excluded. Furthermore, studies of this type showcase the value of including detailed taphonomic studies of microfauna assemblages within multidisciplinary research projects.

Fly ash-slag interaction during alkaline activation: Influence of activators on phase assemblage and microstructure formation

In this work, the influence of activator on the interaction mechanisms between slag and low-calcium fly ash (FA-F) during alkaline activation was investigated. In particular, the evolution of phase assemblage and microstructure of alkali-activated binary slag and FA-F paste was monitored by means of X-ray diffraction with Rietveld analysis, scanning electron microscopy, and energy-dispersive spectroscopy (SEM/EDS). The results show that the nature of amorphous gels and type of crystalline phases formed are dependent on sample age, initial slag to FA-F ratio, and activator type and dosage. The interaction between FA-F and slag during alkaline activation or geopolymerization is primary demonstrated as: (1) modified nanostructure (e.g. crystallology and lattice parameters) and chemical composition of precipitates, (2) depressing or triggering the formation of some crystalline phases, and (3) spatial heterogeneity of composition in microstructure. The activator is chemically incorporated into interactions between slag and FA-F, and likely affects the dissolution and reaction kinetics.

Modified natural magnetite with Al and La ions for the adsorption of fluoride ions from aqueous solutions

Abstract Natural magnetite ore (Fe 3 O 4 ) was modified with aluminum and lanthanum ions to increase the fluoride removal efficiency from aqueous solutions. The modified and unmodified magnetite samples were characterized by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), infrared spectroscopy (IR), surface area (BET) and zeta potential ( ζ ). The adsorption and stability of fluoride on magnetite were investigated using modified magnetite in batch systems. The SEM results indicate the formation of a lanthanum oxide layer around the magnetite and that aluminum oxide is dispersed between the particles. Al and La were deposited as hydroxides (IR), which increased the surface area by 7.5 and 9.5 times higher than natural magnetite and shifted the surface potential toward positive values. The IR results indicated that fluoride replaces a hydroxyl group from the aluminum hydroxides whereas no such replacement was detected for materials with La. Batch tests showed that adsorption increased from 30 to 90% and 96% for the aluminum and lanthanum modified materials, respectively.

Adsorption, oxidation, and reduction behavior of arsenic in the removal of aqueous As(III) by mesoporous Fe/Al bimetallic particles

In this study, mesoporous iron/aluminum (Fe/Al) bimetallic particles were synthesized and employed for the removal of aqueous As(III). Scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), Brunauer-Emmett-Teller (BET) analysis method, Vibrating-sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the Fe/Al bimetals before and after reaction with As(III). The physical properties, compositions, and structures of Fe/Al bimetallic particles as well as the As(III) removal mechanism were investigated. The characterization of the bimetallic particles after the reaction has revealed the removal of As(III) is a complex process including surface adsorption and oxidation, and intraparticle reduction. The good As(III) removal capability and stability of the Fe/Al bimetallic particles exhibited its great potential as an effective and environmental friendly agent for As(III) removal from water.

Aragonite infill in overgrown conceptacles of coralline Lithothamnion spp. (Hapalidiaceae, Hapalidiales, Rhodophyta): new insights in biomineralization and phylomineralogy.

New empirical and quantitative data in the study of calcium carbonate biomineralization and an expanded coralline psbA framework for phylomineralogy are provided for crustose coralline red algae. Scanning electron microscopy (SEM) and energy dispersive spectrometry (SEM-EDS) pinpointed the exact location of calcium carbonate crystals within overgrown reproductive conceptacles in rhodolith-forming Lithothamnion species from the Gulf of Mexico and Pacific Panama. SEM-EDS and X-ray diffraction (XRD) analysis confirmed the elemental composition of these calcium carbonate crystals to be aragonite. After spore release, reproductive conceptacles apparently became overgrown by new vegetative growth, a strategy that may aid in sealing the empty conceptacle chamber, hence influencing the chemistry of the microenvironment and in turn promoting aragonite crystal growth. The possible relevance of various types of calcium carbonate polymorphs present in the complex internal structure and skeleton of crustose corallines is discussed. This is the first study to link SEM, SEM-EDS, XRD, Microtomography and X-ray microscopy data of aragonite infill in coralline algae with phylomineralogy. The study contributes to the growing body of literature characterizing and speculating about how the relative abundances of carbonate biominerals in corallines may vary in response to changes in atmospheric pCO2 , ocean acidification, and global warming.

Passive ultrasonic irrigation in calcium hydroxide removal from root canals: a sem/eds analysis

AIM: The aim of this study was to evaluate the efficacy of different lengths of time of passive ultrasonic irrigation (PUI) in removing calcium hydroxide (CH) paste from root canal, using scanning electron microscopy and energy dispersive spectrometry (SEM/EDS). MATERIAL AND METHODS: Fifty-four human premolars were used. After coronal access, a size #15 K-file was used to obtain apical patency. Root canal preparation was performed using WaveOne 40.08 instruments. CH paste was placed into the root canal. Specimens were stored in a humid environment, and after seven days, they were divided into five groups (n=12) according to the irrigation protocols: Manual– a size #40 K-file; PUI/1– 1 min; PUI/2– 2 min; PUI/3– 3 min; and Control– without CH paste. An elementary chemical microanalysis (SEM/EDS) was performed to quantify the presence of calcium on the dentinal walls. RESULTS: The percentage of calcium was higher in all experimental groups when compared to the control group (P &lt; 0.05); but no differences among them were found (P &gt; 0.05). CONCLUSION: The amount of calcium hydroxide paste on the dentinal walls was not dependent on length of time of ultrasonic activation. SEM/EDS analysis seems to be a reliable method to assess CH paste removal from the root canals.

Discoveries and oddities in library materials

Surprising discoveries can happen while analyzing library materials.This paper presents four case studies focusing on four artifacts of different ages and provenances, all analyzed and studied at the Istituto Centrale per il Restauro e la Conservazione del Patrimonio Archivistico e Librario (Icrcpal). The common denominator amongst the case studies presented in this work, lies in the need for a strong interconnection between the analysis of biological issues and chemical data. The interplay between the two complementary approaches is paramount for the correct interpretation of the status of the material under examination as, as will be shown in the following case studies, chemical data could find an interpretation only in the face of biological observations and vice versa.The first case we here present, deals with two parchment codices that have been found in 2008 during a fishing expedition in the Canale di Sicilia. At that time a deep-sea fishing boat belonging to the fleet of Mazara del Vallo caught in its nets, two artifacts, leading to the first discovery of library materials in the deep sea. The Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analyses allowed for the creation of a compositional map of the surface of the samples, where several microscopic encrusting sea organisms and biogenic materials were also observed. Almost nothing of the original structure of the parchment (of which the object is presumably made) could be recognized at SEM. The absence of the typical collagen features was confirmed by Raman analyses that could only collect spectra of an isoprenic-type polymer of putative biogenic origin.The second case deals with fragments of medieval manuscripts that were found in 2007 buried in the walls of the Great Mosque of Sana'a in Yemen. An outstanding discovery regarded the dark brown inks used on a Qur'ānic fragment attributed to the 10th century. SEM micrographs disclosed the presence of red blood cells mixed to ink components. The inks were also investigated with Raman spectroscopy.The third case study is the book “Libretto di appunti e memorie del Padre Francesco Zazzera”, dated 17th century that presented a peculiar modification of the black ink that appeared to be faded and turned to a white-yellowish color. Raman and SEM analyses recognized and documented a biogenic formation of jarosite on top of the ink. It was possible to remove the jarosite layer and to recover the original black ink, thus allowing an easier reading of the text.The fourth and last case analyzed and presented in this paper consists of the measurements on the invaluable Codex Purpureus Rossanensis dated 6th century. Raman spectroscopy here allowed the demonstration of the use of an elderberry lake to obtain a mauve color. This is the first experimental evidence of the use of that particular dye in such an ancient illuminated manuscript.A sort of archeological discovery was also done on this codex with respect to the past misfortunes that occurred to it; by simply observing some traces we were able to support some intriguing hypothesis on its history and vicissitudes.

Preparation and performance of desiccant coating with modified ion exchange resin on finned tube heat exchanger

In this paper, a desiccant coating with lithium and magnesium modified ion exchange resin (MIER) on finned tube heat exchanger was prepared by impregnation method and electrostatic spraying process, respectively. Impregnation condition and spraying process, which would badly affect the adsorption performance of MEIR desiccant coating, were investigated in detail. Also the morphology, structure, composition and thermal performance of desiccant coating were characterized by X-ray diffractometer (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and temperature programmed desorption (TPD), respectively. Besides, its cycle stability was also taken into consideration. The results manifested that electrostatic spraying technique and impregnation method can be employed to prepare a thick and uniform desiccant coating (120 µm) with modified ion exchange resin on finned tube heat exchanger successfully, which had an excellent cycle stability. The results of TPD analysis showed, for the enhanced interaction between the modified ions and water molecules, desorption activation energy of the modified resin can be raised slightly. And the static and dynamic adsorption curves of modified desiccant coating indicated that, whether in high or low humidity environment, the adsorption performance could be significantly improved after modification.

Influence of temperature on abrasive wear of boron steel and hot forming tool steels

In many industrial applications the occurrence of abrasive wear results in failure and replacement of components. Examples of these applications are found in mining, mineral handling, agriculture, forestry, process and metalworking industry. Some of these applications also involve operation of relatively moving surfaces at elevated temperatures which increases the severity of wear. A typical example of high temperature wear phenomena is that of tool steels during interaction with boron steel in hot forming. Some studies have been carried out regarding the high temperature tribological behaviour of these materials but results pertaining to their high temperature three body abrasive behaviour have not been published in the open literature. In this work, the high-temperature three body abrasive wear behaviour of boron steel and two different prehardened tool steels (Toolox33 and Toolox44) was investigated using a high temperature continuous abrasion machine (HT-CAT) at different temperatures ranging from 20°C to 800°C using a load of 45N and a sliding speed of 1ms−1. The wear results were correlated to the hot hardness of the different materials measured by means of a hot hardness tester (HHT) at a load of 10kgf. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) techniques were used to characterise the worn surfaces. The hot hardness measurements of the three different materials showed a slight but continuous decrease of hardness from room temperature to 600°C. At temperatures above 600°C the hardness showed a sharp decrease. The wear rate of Toolox44 was constant from 20°C to 400°C. On the other hand, Toolox33 and boron steel, showed a reduced wear rate from 20°C to 400°C attributed to an increased toughness and the formation of wear-protective tribolayers respectively. At higher temperatures (from 400°C to 800°C), the wear rate for these materials increased mainly due to a decrease in hardness and the occurrence of recrystallization processes.

Influences of rare earth element Ce-doping and melt-spinning on microstructure and magnetostriction of Fe83Ga17 alloy

In order to improve magnetostriction of the polycrystalline Fe-Ga alloy, the rare earth element Ce was firstly doped into Fe83Ga17 and the melt-spinning method was subsequently applied. The as-cast Fe83Ga17 and Ce-doped Fe83Ga17 alloys were prepared by arc melting. Then the as-cast Ce-doped Fe83Ga17 alloy was melt-spun by the melt-spinning technique. The microstructures and magnetostrictions of all these three alloys were investigated by X-ray diffractometer (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), differential scanning calorimeter (DSC) and magnetostriction measurements. The results indicated that the CeGa2 phase and asymmetrical DO3 phase are formed caused by Ce-doping and melt-spinning, respectively. The magnetostrictions of three alloys are ranked in sequence the melt-spun Fe83Ga17Ce0.8 alloy>as-cast Fe83Ga17Ce0.8 alloy>as-cast Fe83Ga17 alloy. The enhanced magnetostriction is attributed to the fact that the formation of new phases and the preferred orientation along (100) direction.

Dry Sliding Wear Behavior of a High-Mn Austenitic Twinning Induced Plasticity (TWIP) Steel Microalloyed with Ti

ABSTRACTHigh-Mn austenitic twinning induced plasticity (TWIP) steels are the object of intense worldwide scientific study due to the promising combination of strength and ductility of these alloys. Mechanical behavior of this family of new generation steels has been extensively studied recently. However, limited information regarding their tribological properties is available in the literature. The aim of this research work is to study the wear behavior of a high-Mn austenitic Fe–20Mn–1.5Si–1.5Al–0.4C TWIP steel microalloyed with Ti. The wear behavior was evaluated under dry sliding condition by the ‘‘pin-on-ring’’ method. For this purpose, solution-treated samples were worn for 10 km against a counterface disc made of hardened AISI M2 steel, under loads of 52, 103 and 154 N, and at speeds of 0.20, 0.60 and 0.86 m/s. The wear resistance was evaluated from the average wear rate. Wear debris and worn surfaces were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (SEM-EDS). The Ti addition to TWIP steel slightly improved the wear resistance particularly at a speed of 0.86 m/s and at loads of 52 and 103 N. Results show that the wear resistance increases with increasing sliding speed. This is attributed to the formation of an oxide layer acting as a protective layer against wear, which suggests that the main wear mechanism for the studied TWIP steel under these conditions is oxidative.

Experimental Study of Microbial Pyrite Oxidation: A Suggestion for Geologically Useful Biosignatures

The oxidation of pyrite in cultures of Acidithiobacillus ferrooxidans (A.f) was studied. The experiments were performed at an initial pH of 2.5 at 28°C. The concentrations of total dissolved iron in solution and the pH were monitored during the first 36 days. Pyrite surfaces were examined by scanning electron microscopy and energy-dispersive spectrometry (SEM-EDS) after 100 days. The concentrations of total dissolved iron and hydrogen ions increased significantly in the presence of bacteria. SEM examination indicated that the crystal surfaces were subjected to two types of dissolution phenomena. Cracks were observable on the of crystal surfaces under both biotic and abiotic conditions, whereas rounded and polygonal pits appeared additionally on the surfaces under biotic conditions. The co-occurrence of the rounded and polygonal pits on the crystal surfaces and the presence of A.f at the pyrite surface suggests that A.f promotes pyrite oxidation by a contact mechanism. We propose that the rounded and polygonal pits be considered to represent a practical biosignature for tracing the evolution of microbial iron oxidation in the remote past.

The effects of thermal aging on metallic interconnects of solid oxide fuel cells

For solid oxide fuel cells (SOFCs), metallic interconnects (ICs) are crucial components to add to the electrochemical catalyst electrodes. The high temperature operation condition in SOFCs is an extremely degrading factor for metallic ICs. Three metallic ICs have been selected in this thermal aging study. IC-1 and IC-2 contain similar Mn/Cr compositions. The thermal mechanical property of IC-2 is better than that of IC-1, attributed to the inclusion of rare earth elements. IC-3 has lower chromia composition, whereas IC-1 and IC-2 have higher Cr contents. Thermal aging is introduced under ambient atmosphere at 800°C from 0 to 100 h. X-ray diffraction study of the IC oxide scales shows growth of (MnCr)3O4 with the spinel structures. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) reveal the thickness and spinel particles for the three ICs, the oxide layers at about 0·9–1·3 μm thick and the spinel sizes at 1·0–1·3 μm. The oxide weight gain studies have shown that IC-3 is the more readily oxidised IC, with an estimated oxidation rate of ∼1·98×10−7 g2 cm−4 s−1 at 800°C. Thus, IC-3 should be better coated with a protective layer for SOFC applications. For the thermal Cr diffusion study, we applied homemade glass sealant on the surface of IC-1. After thermal aging for 1000 h under ambient atmosphere at 800°C, we examined the sample with micro-Raman. The cross-sectional microstructures were studied with SEM/EDS. Both Raman and SEM/EDS results indicated that the Cr ions penetrated into the glass sealant by ∼65 μm. The oxide scales on ICs are influential on the electrical conductivity. The electrochemical impedance spectroscopy study on IC-2 samples after thermal aging is also shown.

Ultra‐short vertically aligned carbon nanofibers transfer and application as bonding material

PurposeThe transferred carbon nanofibers (CNFs) can be applied in flip chip package as interconnect material, as an alternative to the conventional solder and conductive adhesive (CA) materials.Design/methodology/approachThe structure of CNFs was confirmed by transmission electron microscopy (TEM). The electrical performance of the vertically aligned carbon nanofibers (VACNFs) joint was measured by four points probe method and compared to conventional lead‐free solder Sn3.0Ag0.5Cu, pure indium and silver CA. A shear test was carried out in order to evaluate the mechanical performance of VACNFs joint. After the shear test, the fracture surface was analyzed by scanning electron microscopy and energy dispersive spectroscopy (SEM‐EDS).FindingsThe results showed a high success rate in the transfer of VACNFs from growth chip to target chip. The Au‐coated CNF can be wetted well with melted indium during the transfer and bonding process. In‐Au intermetallic compound (IMC) formed on the surface of CNF. The electrical and mechanical performance of VACNFs is comparable to that of the traditional interconnect materials. The fracture surface is located at the interface between VACNFs and chips. The stacked‐cone structure of CNF can be confirmed from a cross‐section of the break CNF by TEM.Originality/valueUltra‐short VACNFs were grown and first successfully transferred to the target chip using a process which required little pressure, low temperature and short time.