scholarly journals Surface Characterization and Secondary Electron Emission Properties of Alumina Containing MgO Film on Ag-Mg-Al Alloy

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 570 ◽  
Author(s):  
Fan Zhou ◽  
Quan Zhang ◽  
Feifei Wang ◽  
Jing Wang ◽  
Yunfei Yang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Secondary Electron ◽  
Energetic Electron ◽  
Electron Bombardment ◽  
Mg Alloy ◽  
Al Alloy ◽  
Activation Process ◽  
Low Oxygen ◽  
Electron Multiplier

Ag-Mg alloy is used as a dynode material in electron multiplier tubes due to the high secondary electron yields (δ) of the surface of MgO film. However, MgO film is readily degraded under strong electron or ion bombardment, which results in a decrease in the lifetime of devices. In this study, alumina-containing MgO films of ~50–150 nm were developed on a Ag-2Mg-2Al alloy (silver alloy containing 2 wt % Mg and 2 wt % Al) after a thermal activation process performed at 500–600 °C under low oxygen pressures of 5.0–20.0 Pa. Auger electron spectroscopy and X-ray photoelectron spectroscopy analyses reveal that the film consists of a thin layer of pure MgO and a relatively thicker layer of alumina-containing MgO located beneath the top MgO layer. The alumina-containing MgO film exhibits high δ value of 7.7 at a primary electron energy of 580 eV and a much better stability under energetic electron bombardment than pure MgO film on Ag-Mg alloy. Alumina has higher bond dissociation energy than MgO, and the presence of alumina in the film contributes to mitigating the dissociation of the MgO film under electron bombardment. The Ag-2Mg-2Al alloy with alumina-containing MgO film is a promising candidate as a dynode material for electron multiplier tubes.

SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

1978 ◽  
Vol 36 (1) ◽  
pp. 524-525
Author(s):  
T. Koshikawa ◽  
Y. Fujii ◽  
E. Sugata ◽  
F. Kanematsu
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Life Time ◽  
Activation Process ◽  
Beam Diameter ◽  
Activation Temperature ◽  
Electron Multiplier ◽  
Activation Condition ◽  
Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

Surface Characterization of an Extruded 6060 Al Alloy

2007 ◽  
Vol 29-30 ◽  
pp. 67-70
Author(s):  
Wei Zhang ◽  
Jim Metson ◽  
C.L. Nguyen ◽  
S. Chen
Keyword(s):  
Aluminium Alloy ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Extrusion Direction ◽  
Surface Characteristics ◽  
Al Alloy ◽  
X Ray ◽  
Film Instability ◽  
Mg Content

The surface characteristics of an extruded 6060 aluminium alloy were investigated with X-ray Photoelectron Spectroscopy (XPS). The results revealed that the extruded surface was covered by oxides of aluminium and magnesium. The thickness of aluminium oxide was found to change along the extrusion direction with the thinnest and thickest oxide at the beginning and end of the extrudate, respectively. Magnesium segregation was found on the surface of the extrusion with the highest and lowest Mg concentration at the beginning and end of the extrudate, respectively. This is the inverse result of that expected where increasing Mg content was believed to be associated with film instability and thicker films.

scholarly journals Experimental Apparent Stern–Geary Coefficients for AZ31B Mg Alloy in Physiological Body Fluids for Accurate Corrosion Rate Determination

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 391
Author(s):  
Federico R. García-Galvan ◽  
Santiago Fajardo ◽  
Violeta Barranco ◽  
Sebastián Feliu
Keyword(s):  
Weight Loss ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Product Layer ◽  
Mg Alloy ◽  
Corrosion Rates ◽  
Corrosion Product Layer ◽  
The Relationship ◽  
Phosphate Buffered Saline

The corrosion behavior of AZ31B Mg alloy exposed to Ringer’s, phosphate-buffered saline (PBS), Hank’s, and simulated body fluid (SBF) solutions for 4 days was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, weight loss, and surface characterization. Changes in corrosion rates with immersion time determined by weight loss measurements were compared with EIS data to determine the possibility of obtaining quantitative electrochemical information. In addition, changes in the protective properties of the corrosion product layer calculated from the EIS parameters were evaluated as a function of their surface chemical composition as determined by X-ray photoelectron spectroscopy (XPS) and visual observations of the corroded specimen’s surface. Apparent Stern–Geary coefficients for the AZ31B Mg alloy in each test solution were calculated using the relationship between icorr from weight loss measurements and the EIS data (both Rp and Rt). This provided experimental reference B′ values that may be used as a useful tool in independent investigations to improve the accuracy of corrosion rates of AZ31B Mg alloy in simulated body solutions.

Direct Cladding from Molten Metals of Aluminum and Magnesium Alloys Using a Tandem Horizontal Twin Roll Caster

2015 ◽  
Vol 772 ◽  
pp. 250-256 ◽  
Author(s):  
Hideto Harada ◽  
Shin Ichi Nishida ◽  
Mayumi Suzuki ◽  
Hisaki Watari ◽  
T. Haga
Keyword(s):  
Surface Condition ◽  
Hardness Test ◽  
Al Alloys ◽  
Mg Alloy ◽  
Al Alloy ◽  
Molten Metals ◽  
Electron Probe Micro Analyzer ◽  
Twin Roll Caster ◽  
Aluminum And Magnesium Alloys ◽  
Twin Roll

This paper describes direct cladding of magnesium (Mg) and aluminum (Al) alloys using a tandem horizontal twin roll caster that has three pairs of upper and lower rolls. Manufacturing conditions that are appropriate for fabricating Al/Mg and Al/Mg/Al cladded material were investigated. The surface condition of the cladded cast strip was examined. An electron probe micro analyzer was used to observe the interface between Al alloy and Mg alloy. The thickness of the mixed layer of Al and Mg alloy was 15μm, and how the materials were connected was clarified. Microscopic observation and backscattered electron analysis were used to investigate the cladding mechanisms of the Al and Mg alloy layers. Average hardness was determined using the Vickers hardness test at the Al layer and at the diffused layer between Mg and Al alloys. Cladding of Al/Mg alloy and A/Mg/Al alloy was possible using a tandem twin-roll caster. In addition, Al3Mg2 and Al12Mg17 phase precipitation at the interface of the Al and Mg alloys was confirmed during direct cladding from molten metals.

Surface characterization and redox behaviour of iron-containing bismuth molybdovanadates by X-ray photoelectron spectroscopy

1988 ◽  
Vol 12 (4) ◽  
pp. 273-274 ◽  
Author(s):  
D. Gazzoli ◽  
A. Anichini ◽  
S. De Rossi ◽  
M. Lo Jacono ◽  
P. Porta ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
X Ray ◽  
Redox Behaviour

Surface Characterization and In Vitro Blood Compatibility of Poly(Ethylene Terephthalate) Immobilized with Hirudin

2005 ◽  
Vol 288-289 ◽  
pp. 421-424
Author(s):  
F. Li ◽  
Jin Wang ◽  
H. Sun ◽  
Nan Huang
Keyword(s):  
Free Energy ◽  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Ethylene Terephthalate ◽  
Blood Compatibility ◽  
Argon Plasma ◽  
Angle Measurement ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Poly(ethylene terephthalate) films were exposed under argon plasma glow discharge and induced polymerization of acrylic acid (AA) in order to introduce carboxylic acid group onto PET (PET-AA) assisting by ultroviolet radiation. Hirudin-immobilized PETs were prepared by the grafting of PET-AA, followed by chemical reaction with hirudin. The surface structure of the treated PET is determined by X-ray photoelectron spectroscopy (XPS). The wettability and surface free energy, interface free energy of the films is investigated by contact angle measurement. Platelet adhesion evaluatiion is conducted to examine the blood compatibility in vitro. Scanning electron microscopy (SEM) and optical microscopy reveal that the amounts of adhered, aggregated and morphologically changed platelets are reduced on hirudin-immobilized PET films.

Surface Characterization of W/Ni/Al2O3 Catalysts

1997 ◽  
Vol 497 ◽  
Author(s):  
M. H. Jordão ◽  
J. M. Assaf ◽  
P. A. P. Nascente
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Surface Characterization ◽  
Nickel Content ◽  
Stable Phase ◽  
Preparation Methods ◽  
X Ray ◽  
Inductively Coupled ◽  
Temperature Programmed ◽  
Two Phases

ABSTRACTCatalysts containing tungsten and nickel oxides are important in hydrodesulfurization (HDS), hydrogénation (HY), and steam reforming of hydrocarbons. A series of W/Ni/Al2O3 catalysts was prepared by two different methods: (1) coprecipitation of nickel and aluminium hydroxicarbonate from their nitrates, followed by calcination and impregnation of tungsten; (2) precipitation of boehmite from aluminium nitrate, followed by impregnations of nickel, firstly, and tungsten. The nickel content was kept constant, while the amount of tungsten varied from 2.5 to 15.5 wt-%. The resulting oxides were characterized by inductively coupled plasma spectroscopy (ICP), atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). ICP and AAS were used to determine the W, Ni, and Al concentrations. XRD detected two phases: NiO and NiAl2O4 (no phase containing metallic tungsten was detected). Increasing the amount of W, the quantity of NiAl2O4 rose, the quantity of NiO decreased, and the particle size of NiO enlarged. The TPR profiles presented three peaks: one at about 1000 °C, associated to a very stable phase; for the samples prepared by coprecipitation, the other two peaks corresponded to “free NiO” and a nonstoichiometric aluminate. For the samples prepared by impregnation, those peaks corresponded to NiO and NiAl2O4. XPS identified Al2O3, NiAl2O4, and Al2(WO4)3 for both preparation methods. Increasing the amount of tungsten in the impregnated samples, NiWO4 was also observed.

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