Effect of stearic acid coating on anti-oxidation property of Sn-Ag-Cu solder powder

2019 ◽  
Vol 31 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Fen Peng ◽  
Wensheng Liu ◽  
Yufeng Huang ◽  
Siwei Tang ◽  
Chaoping Liang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Stearic Acid ◽  
Photoelectron Spectroscopy ◽  
Hydroxyl Group ◽  
Phase Method ◽  
Layer By Layer ◽  
Content Type ◽  
Maximum Angle ◽  
Coated Powder

Purpose The purpose of this study is to develop a monolayer surface coating of stearic acid on Sn-Ag-Cu solder powder to limit oxidation. Design/methodology/approach Stearic acid was adsorbed onto Sn-Ag-Cu solder powder through liquid-phase adsorption. The isotherm of adsorption was measured and then the microstructure of coated powder was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Findings The adsorption isotherm of stearic acid on the powder was “H” type, which revealed the layer-by-layer adsorption on non-porous surface. When the concentration of solution was in the range of 0.001-0.006 mol/L, with an adsorption amount of 0.12 ± 0.1 mg/g, monolayer stearic acid covered the solder powder completely. Uniform and integrated self-assembled monolayer coating was formed through hydrogen bonds between the oxygen ions in surface lattice of Sn3.0Ag0.5Cu solder powder and the —O—H hydroxyl group of stearic acid. The maximum angle of stability of coated powder also reduced by 2.87° compared with that of non-coated powder. The increase rate of oxygen content of coated powder was much slower than that of non-coated powder when they were exposed to humid air. Originality/value As a result, oxidation of fine solder powder was effectively limited. Essentially, this method can also be applied to the coating of other types of solder powder and has reference significance to other coating by liquid-phase method.

Comparison of fabrication methods for the effective loading of Ag onto PVA nanofibers

2018 ◽  
Vol 89 (4) ◽  
pp. 625-634 ◽  
Author(s):  
Davood Kharaghani ◽  
Hoik Lee ◽  
Takahiro Ishikawa ◽  
Tomoki Nagaishi ◽  
Seong Hun Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Ag Nanoparticles ◽  
Inductively Coupled Plasma ◽  
Composite Nanofibers ◽  
Reduction Method ◽  
Reduction Process ◽  
Hydroxyl Group ◽  
Immersion Method ◽  
Ag Particles

We investigated and compared three different methods for synthesizing Ag/PVA nanofibers by effectively dispersing and loading Ag particles onto PVA nanofibers and preventing the detachment of Ag from the nanofibers. The three methods were: (a) the solution reduction method (Method 1) in which the reduction of Ag+ was conducted before electrospinning, resulting in mixing the polymer and the Ag nanoparticles in the electrospinning solution; (b) the immersion method (Method 2) in which electrospun PVA nanofibers were immersed in the Ag+ solution, resulting in loading the Ag particles onto the PVA nanofibers; and (c) the nanofiber reduction method (Method 3) in which the Ag+/PVA solution underwent electrospinning followed by the reduction process with Ag+/PVA nanofibers. All of the electrospun nanofibers had a crosslinked structure that resulted from the chemical reaction of glutaraldehyde with the hydroxyl group of PVA, to prevent dissolution in the aqueous solution. Fourier transform infrared spectra provided evidence of the successful formation of the crosslinked structure of the nanofibers, and x-ray photoelectron spectroscopy and transmission electron microscopy confirmed the loading of Ag nanoparticles onto the nanofibers. The release profiles were investigated by inductively coupled plasma, and the morphology of the nanofibers was observed by scanning electron microscopy. Method 3 had the best performances for loading Ag particles onto the nanofibers and for minimizing the loss of Ag nanoparticles from the nanofibers. These findings identified an effective method for fabricating metal/polymer composite nanofibers, and will allow the expansion of the applications of metal/polymeric composite nanofibers.

scholarly journals Selective Liquid-Phase Oxidation of Toluene with Molecular Oxygen Catalyzed by Mn3O4 Nanoparticles Immobilized on CNTs under Solvent-Free Conditions

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 623
Author(s):  
Yuwei Feng ◽  
Aiwu Zeng
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Benzyl Alcohol ◽  
Photoelectron Spectroscopy ◽  
Supported Catalysts ◽  
Liquid Phase Oxidation ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Phase Oxidation ◽  
Mn3o4 Nanoparticles

The catalytic performance of Mn3O4 supported on carbon nanotubes (CNTs) in the liquid-phase oxidation of toluene to benzyl alcohol and benzaldehyde was studied. The supported catalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherms and ICP-MS. The results demonstrate that Mn3O4 nanoparticles loaded on CNTs performed better compared with pristine Mn3O4 or CNTs. The main reason for the increased catalytic activity is the dispersion and loading of Mn3O4 in CNTs. By optimizing the reaction temperature, reaction time, catalyst quality, oxygen flow rate and initiator dosage, the optimum reaction conditions were obtained. Using tert-butyl hydroperoxide (TBHP) as the initiator and oxygen as the oxidant, the toluene conversion rate was as high as 24.63%, and benzyl alcohol and benzaldehyde selectivity was 90.49%. The good stability of the catalyst was confirmed by repeating the experiment for four cycles and observing no significant changes in its performance.

scholarly journals Effect of the Fluorine Substitution for –OH Group on the Luminescence Property of Eu3+ Doped Hydroxyapatite

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 191 ◽  
Author(s):  
Xiaojun Zhang ◽  
Qingguo Xing ◽  
Lixuan Liao ◽  
Yingchao Han
Keyword(s):  
Electron Microscopy ◽  
Phase Composition ◽  
Photoelectron Spectroscopy ◽  
Hydroxyl Group ◽  
Fluorine Substitution ◽  
Luminescence Enhancement ◽  
X Ray ◽  
Fluoridated Hydroxyapatite ◽  
Chemical Structures ◽  
Substitution Ratio

In this study, different fluoridated hydroxyapatite doped with Eu3+ ion nanoparticles were prepared by the hydrothermal method. The relationship between luminescence enhancement of Eu3+ ions and a fluorine substitution ratio for hydroxyl group in hydroxyapatite was discussed. Moreover, the effect of fluorine substitution for a hydroxyl group on phase composition, crystallinity, and crystal size was studied. Phase composition and chemical structures were identified by X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) Spectroscopy analyses. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) patterns were performed to analyze the morphology and particle size. X-ray Photoelectron Spectroscopy (XPS) patterns were observed to analyze fluorine substitution for the hydroxyl group and chemical state of Eu3+ ions in fluoridated hydroxyapatite. The results of these experiments indicated that the samples with a different fluorine substitution ratio were prepared successfully by maintaining the apatite structure. With an increasing fluorine substitution ratio, the morphology maintained a rod-like structure but the aspect ratio tended to decrease. XPS patterns displayed that the fluorine replaced the hydroxyl group and brought environmental variation. The fluorine ions could affect the crystal field environment and promote luminescence conversion. There was a linear relationship between the fluorine substitution ratio and luminescence enhancement.

A simple method to prepare carbon nanotubes from sunflower seed hulls and sago and their application in supercapacitor

2015 ◽  
Vol 44 (1) ◽  
pp. 7-12 ◽  
Author(s):  
H.Y. Zhang ◽  
H.J. Niu ◽  
Y.M. Wang ◽  
C. Wang ◽  
X.D. Bai, ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Photoelectron Spectroscopy ◽  
Sunflower Seed ◽  
Electrochemical Impedance ◽  
Cyclic Voltammograms ◽  
Production Scale ◽  
Simple Method ◽  
Content Type ◽  
X Ray

Purpose – The purpose of this paper was to provide a simple method for the preparation of carbon nanotubes (CNTs) by pyrolysing sunflower seed hulls and sago and to evaluate the application of such CNTs in supercapacitors. Design/methodology/approach – The CNTs were obtained by pyrolysing sunflower seed hulls and sago at 800°C. The prepared CNTs were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammograms, galvanostatic charge and discharge and electrochemical impedance spectra methods. Findings – The CNTs had large surface areas as determined by the methylene blue method and the Brunauer – Emmett – Teller method. And the CNTs that were prepared by pyrolysing the natural sunflower seed hulls (denoted as CNTs-1) and sago (denoted as CNTs-2) had capacitances of 86.9 F/g and 26.7 F/g, respectively. Research limitations/implications – The capacitances of CNTs can be further improved. Practical implications – The exceptional electronic and mechanical properties of CNTs prepared lend the CNTs to diverse applications including electrocatalysts, hydrogen storage, photovoltaic devices actuators, energy storage, field-emitting flat panel displays and composites. Originality/value – Currently, CNTs have not yet been used in the industry at a mass production scale due to high costs associated. The outcomes of the study reported in this article could provide a convenient method in aid of industrialisation of the production of CNTs.

scholarly journals Elasticity of Cross-Linked Titania Nanocrystal Assemblies Probed by AFM-Bulge Tests

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1230 ◽  
Author(s):  
Hensel ◽  
Schröter ◽  
Schlicke ◽  
Schulz ◽  
Riekeberg ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Edge Length ◽  
Film Deposition ◽  
Layer By Layer ◽  
Functional Coatings ◽  
Transmission Electron ◽  
Dodecanedioic Acid ◽  
And Control

In order to enable advanced technological applications of nanocrystal composites, e.g., as functional coatings and layers in flexible optics and electronics, it is necessary to understand and control their mechanical properties. The objective of this study was to show how the elasticity of such composites depends on the nanocrystals’ dimensionality. To this end, thin films of titania nanodots (TNDs; diameter: ~3–7 nm), nanorods (TNRs; diameter: ~3.4 nm; length: ~29 nm), and nanoplates (TNPs; thickness: ~6 nm; edge length: ~34 nm) were assembled via layer-by-layer spin-coating. 1,12-dodecanedioic acid (12DAC) was added to cross-link the nanocrystals and to enable regular film deposition. The optical attenuation coefficients of the films were determined by ultraviolet/visible (UV/vis) absorbance measurements, revealing much lower values than those known for titania films prepared via chemical vapor deposition (CVD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed a homogeneous coverage of the substrates on the µm-scale but a highly disordered arrangement of nanocrystals on the nm-scale. X-ray photoelectron spectroscopy (XPS) analyses confirmed the presence of the 12DAC cross-linker after film fabrication. After transferring the films onto silicon substrates featuring circular apertures (diameter: 32–111 µm), freestanding membranes (thickness: 20–42 nm) were obtained and subjected to atomic force microscopy bulge tests (AFM-bulge tests). These measurements revealed increasing elastic moduli with increasing dimensionality of the nanocrystals, i.e., 2.57 ± 0.18 GPa for the TND films, 5.22 ± 0.39 GPa for the TNR films, and 7.21 ± 1.04 GPa for the TNP films.

Effect of engine oil additives reduction on the tribofilm structure of a cylinder liner model surface

2019 ◽  
Vol 72 (4) ◽  
pp. 515-523
Author(s):  
Maria de Lourdes Miranda-Medina ◽  
Christian Tomastik ◽  
Tia Truglas ◽  
Heiko Groiss ◽  
Martin Jech
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cylinder Liner ◽  
Engine Oil ◽  
Antiwear Additives ◽  
Content Type ◽  
X Ray ◽  
Underlying Mechanisms

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.

Transient liquid phase bonding in the Cu-Sn system

2019 ◽  
Vol 31 (4) ◽  
pp. 221-226
Author(s):  
Behnam Hosseinzaei ◽  
Ali Reza Kiani Rashid
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Liquid Phase ◽  
Transient Liquid Phase ◽  
Bonding Process ◽  
Bonding Interface ◽  
Phase Method ◽  
Shear Tests ◽  
Content Type ◽  
Ε Phase

Purpose This paper aims to study the features of microstructures and mechanical properties of the joints which were produced by transient liquid phase method. The difference between phases in bonding region identified through metallography pictures and applying hardness and shear strength tests. Design/methodology/approach The bonding process was carried out at a temperature of 300°C for time durations ranging from 15 to 120 min. The scanning electron microscopy equipped with energy dispersive spectroscopy system and optical microscopy were used to examine microstructural characteristics, and mechanical properties of the joints were studied by applying microhardness and shear tests. The shear tests were conducted by a shear fixture which was mounted on the tensile machine. Findings The intermetallic compounds of the Cu6Sn5 −η and the Cu3Sn-ε were formed simultaneously in the bonding interface. Although the η-phase, which exhibits scallop-shaped morphology, grows very quickly, upon completion of the isothermal solidification stage, it turns into the ε-phase. The hardness of the bonding interface is significantly higher than that of the substrate. The shear results show that once the bonding process is complete, brittle fracture occurs. Moreover, a greater decrease in strength was observed when the ε-phase is the only phase in the bonding region. Originality/value The hardness number of the η-phase is higher than that of the ε-phase. The hardness numbers of the η-phase and the ε-phase are 894 and 689 HV, respectively. The mean shear strength values of the samples that were bonded at 300 °C for 15, 60 and 120 min were 11.7, 9.5 and 5.4 MPa, respectively.

Template-free fabrication of NiO nanobelts: promising candidate for ethanol gas sensor at room temperature

2016 ◽  
Vol 33 (2) ◽  
pp. 68-72 ◽  
Author(s):  
Zhiwei Li
Keyword(s):  
Electron Microscopy ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Hydrothermal Reaction ◽  
Ethanol Vapor ◽  
Promising Candidate ◽  
Content Type ◽  
X Ray ◽  
Template Free

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.

Tribological properties of carbonized polydopamine/rGO composite coatings

2019 ◽  
Vol 72 (1) ◽  
pp. 54-65
Author(s):  
Ming Yang ◽  
Zhengfeng Jia ◽  
Denghu Wei ◽  
Yunxia Wang ◽  
Xianjuan Pang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Composite Coatings ◽  
Copper Substrate ◽  
Friction Reduction ◽  
Wear Properties ◽  
Content Type ◽  
X Ray

Purpose The purpose of this paper is to investigate the tribological properties of carbonized polydopamine/reduced graphene oxide (CPDA/rGO) composite coatings. Design/methodology/approach CPDA/rGO composite coatings were prepared using the spray technique and subsequent pyrolysis under argon. The transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy revealed the conversion of PDA and GO into CPDA and rGO, respectively. Findings The results of tribological investigations show that the CPDA/rGO composite coatings with heat treatment at 300°C possess much better friction-reduction and anti-wear properties. Originality/value The worn surfaces of the PDA/GO composite films after heat treatment at 300°C were much smoother than that of the copper substrate. The tribofilms containing C, N, O and Cu played an important role on reducing friction and increasing wear resistance.

Identification of hepatitis a virus in cell cultures by solid phase immune electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 238-239
Author(s):  
C.D. Humphrey ◽  
T.L. Cromeans ◽  
E.H. Cook ◽  
D.W. Bradley
Keyword(s):  
Electron Microscopy ◽  
Liquid Phase ◽  
Cell Cultures ◽  
Rapid Detection ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Solid Phase ◽  
Immune Electron Microscopy ◽  
Detection And Identification

There is a variety of methods available for the rapid detection and identification of viruses by electron microscopy as described in several reviews. The predominant techniques are classified as direct electron microscopy (DEM), immune electron microscopy (IEM), liquid phase immune electron microscopy (LPIEM) and solid phase immune electron microscopy (SPIEM). Each technique has inherent strengths and weaknesses. However, in recent years, the most progress for identifying viruses has been realized by the utilization of SPIEM.

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