Cementation of Copper on Pure Aluminum: Analysis of the Two-Step Rate Mechanism by Scanning Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 304-305
Author(s):  
V. Annamalai
Keyword(s):  
Structural Characteristics ◽  
Pure Aluminum ◽  
Secondary Electron Emission ◽  
Reaction Rates ◽  
Copper Deposits ◽  
Step Rate ◽  
Rotating Discs ◽  
Emission Mode ◽  
Rate Mechanism ◽  
Scanning Electron

Iron has been the major source of the precipitant metal in the copper cementation process. Aluminum, due to its abundant availability in the form of beverage cans, has been used successfully in the process in laboratory experiments1. In a recent study of the cementation of the Cu2+/pure A1 system2, it was found that the reaction rates followed a distinct two-step rate mechanism. This paper presents a physical explanation of the two-step rate mechanism on the basis of the structural characteristics of the copper deposits.A specially designed cementation cell along with aluminum (99.99% pure) rotating discs was used in this study2. Ultrasonic experiments were conducted using an 80 watt Bransonic 12 ultrasonic cleaner. Copper deposits were examined in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25 KV in the secondary electron emission mode.In most of the experiments, two distinct kinetic regions were observed, namely an initial slow rate followed by a final enhanced rate.

SEM analysis of the change in the reaction rates with deposit structures in the copper-iron cementation system

1978 ◽  
Vol 36 (1) ◽  
pp. 456-457
Author(s):  
V. Annamalai ◽  
L.E. Murr
Keyword(s):  
Structural Characteristics ◽  
Secondary Electron Emission ◽  
Copper Deposit ◽  
Reaction Rates ◽  
Sem Analysis ◽  
Experimental Conditions ◽  
Major Drawback ◽  
Emission Mode ◽  
Scrap Iron ◽  
Image Position

Economical recovery of copper metal from leach liquors has been carried out by the simple process of cementing copper onto a suitable substrate metal, such as scrap-iron, since the 16th century. The process has, however, a major drawback of consuming more iron than stoichiometrically needed by the reaction.Therefore, many research groups started looking into the process more closely. Though it is accepted that the structural characteristics of the resultant copper deposit cause changes in reaction rates for various experimental conditions, not many systems have been systematically investigated. This paper examines the deposit structures and the kinetic data, and explains the correlations between them.A simple cementation cell along with rotating discs of pure iron (99.9%) were employed in this study to obtain the kinetic results The resultant copper deposits were studied in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25kV in the secondary electron emission mode.

Scanning Electron Microscopy of Single-Crystal NiO Energetics

1975 ◽  
Vol 33 ◽  
pp. 68-69
Author(s):  
L. E. Murr ◽  
C.J. Miglionico
Keyword(s):  
Single Crystal ◽  
Secondary Electron Emission ◽  
Structural Features ◽  
Emission Mode ◽  
Hydrogen Flame ◽  
Negative Crystal ◽  
Growth Features ◽  
Negative Growth ◽  
Scanning Electron ◽  
Made In

The fusion of NiO powder in an oxygen-rich oxy-hydrogen flame at ∼2000°C at atmospheric pressure has been observed to produce, in addition to single-crystal Ni growth, a residual (001) vicinal NiO growth which exhibits an intergrowth and regrowth of isolated particles characterized as equilibrium (regular-faced) polyhedra, and a prominent “negative crystal” phenomena in the vicinal faces of the oxide. Observations of the NiO crystal growth and particle morphologies were made in a JE0L-JSM-50A scanning electron microscope operated at 25 kV in the secondary electron emission mode. The samples were uncoated.Figure 1(a) shows typically the NiO growth phenomena observed, while Fig. 1(b) illustrates the vicinal-surface growth features schematically. The major structural features can be characterized as terraces, ledges, and kinks, with "negative" growth features related to systematic terrace-atom desorption.

scholarly journals Material Application of a Transformer Box: A Study on the Electromagnetic Shielding Characteristics of Al–Ta Coating Film with Plasma-Spray Process

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 495 ◽  
Author(s):  
Fei-Shuo Hung
Keyword(s):  
Stainless Steel ◽  
Structural Characteristics ◽  
Steel Substrate ◽  
Pure Aluminum ◽  
Multilayer Coating ◽  
Thickness Effect ◽  
Stress Effect ◽  
Coating Film ◽  
Coating Structure ◽  
Frequency Condition

In this study we present the results of two experiments. In the first one, a Ta–Al–SS (stainless steel (SS)) multilayer coating structure was prepared using plasma spraying equipment to investigate the coating structure and interface properties. In the second one, Ta–Al on multilayer glass was prepared using the sputtering process to measure the thickness effect of thin film on electromagnetic wave shielding (EMI) characteristics and on the design of high-power switchboard covers. According to the experimental results, the multilayer structure of Ta–Al on SS improves the mechanical properties of a stainless steel plate by enhancing the explosion-proof property. An appropriate thickness of the plasma-sprayed pure aluminum layer can increase the adhesion to the stainless steel substrate and buffer the stress effect. After heat treatment (annealing), the Ta–Al–SS multilayer structural characteristics are excellent and suitable for shielding effects at different temperatures and humidity, which can be used as a reference for the engineering application of communication rooms and base power stations. According to EMI test of multi-coated glass (Ta–Al–glass), by increasing the thickness of Ta layer, we cannot effectively improve full-frequency EMI shielding with improved shielding at low-mid frequency condition. In addition, the Ta–Al interface formation of an Al–Ta–O compound layer can improve the adiabatic effect to reduce the thermal conductivity.

Examination of whewellite kidney stones by scanning electron microscopy and powder neutron diffraction techniques

2009 ◽  
Vol 42 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Michel Daudon ◽  
Dominique Bazin ◽  
Gilles André ◽  
Paul Jungers ◽  
Alain Cousson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Neutron Diffraction ◽  
Kidney Stones ◽  
Structural Characteristics ◽  
Calcium Oxalate Monohydrate ◽  
Atomic Scale ◽  
Mesoscopic Scale ◽  
Powder Neutron Diffraction ◽  
Scanning Electron

Kidney stones made of whewellite,i.e.calcium oxalate monohydrate, exhibit various morphological aspects. The crystalline structure of whewellite at the atomic scale was revisited through a single-crystal neutron study at room temperature using a four-circle automated diffractometer. The possible relationships between the various morphological types of whewellite stones and their structural characteristics were examined at the mesoscopic scale by the use of scanning electron microscopy and at the nanometric scale by powder neutron diffraction. All types of whewellite stones displayed a similar structure at the nanometric scale. However, significant differences were found at the mesoscopic scale. In particular, the crystallites in kidney stones resulting from a genetic hyperoxaluria exhibited a peculiar structure. There was a close relationship between stone morphology and crystallite organization at the mesoscopic level and the effectiveness of extracorporeal shockwave lithotripsy.

New Instrumental Techniques and Their Application to Electron Microprobe Analysis and Scanning Electron Microscopy

1970 ◽  
Vol 24 (4) ◽  
pp. 420-426 ◽  
Author(s):  
James P. Smith ◽  
Lee R. Reid
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Microprobe ◽  
Secondary Electron Emission ◽  
Rate Analysis ◽  
Quantitative Measurements ◽  
Modulation Techniques ◽  
New Instrumentation ◽  
Phase Sensitive ◽  
Scanning Electron

This paper reviews several applications of new instrumentation which have been developed for the electron microprobe analyzer and the scanning electron microscope. By using signal modulation techniques and phase sensitive detection, the information from the scanning electron microscope is made more quantitative. Digital techniques applied to photomultiplier outputs allow more sensitive and quantitative measurements of cathodoluminescence intensities and secondary electron emission. The technique of pulse rate analysis is used to enhance the information contained in x-ray scanning micrographs from an electron microprobe analyzer. Several examples of these techniques are discussed.

MASSIVE COPPER SULPHIDE MINERALIZATION IN DOLOMITES FROM THE LUBIN MINE (FORE-SUDETIC MONOCLINE)

2017 ◽  
pp. 29-48 ◽  
Author(s):  
Piotr Król ◽  
Zbigniew Sawłowicz
Keyword(s):  
Cross Sections ◽  
Copper Sulphide ◽  
Copper Deposits ◽  
Sulphide Mineralization ◽  
Ore Mineralization ◽  
First Time ◽  
Mineralizing Fluids ◽  
Scanning Electron

Massive ore mineralization in dolomites is described for the first time from the Fore-Sudetic copper deposits. Three cross-sections from the Lubin Mine were studied using polarized optical (PLM) and scanning electron (SEM-EDS) microscopy, also cathodoluminescence (CL) and XRD. Massive mineralization, composed mainly of chalcocite with calcite admixture, occurs in dolomites as horizontal pseudovein, locally underlain by clay-carbonate breccia and shale. Underlying dolomites were partly calcitized (dedolomitized). Various calcite generations are characterized in detail. A model of the formation of massive mineralization is proposed. Mesotectonic intralayer movements caused the cracking of dolomite layers and the formation of breccia. Calcitization led to both dedolomitization and the partial infilling of cracks. Mineralizing fluids infilled the cracks completely, partly replacing calcite and adjacent rocks.

Preparation of ZnAl2O4 Spinel Directly from Zinc Aluminum Layered Double Hydroxide Precursor

2012 ◽  
Vol 567 ◽  
pp. 127-130
Author(s):  
Jian Ye Song ◽  
Ming Zhe Leng ◽  
Xing Qi Fu ◽  
Jian Qiang Liu
Keyword(s):  
Layered Double Hydroxide ◽  
Single Phase ◽  
Structural Characteristics ◽  
Atomic Level ◽  
X Ray Diffraction ◽  
Simple Route ◽  
X Ray ◽  
Znal2o4 Spinel ◽  
Double Hydroxide ◽  
Scanning Electron

Single-phase ZnAl2O4 spinel has been prepared by a novel simple route using layered double hydroxide as a precursor. ZnAl2O4 spinel is directly obtained by calcination of zinc aluminum layered double hydroxide (Zn/Al molar radio is 0.5) without further chemical treatment. The key feature of this method is that it affords uniform distribution of all metal cations on an atomic level in the precursor. The structural characteristics of the as-synthesized precursor and the resulted calcined products are obtained by X-ray diffraction and scanning electron microscope.

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