Optimization of composition and structure of electrodeposited Ni–Cr composites for increasing the oxidation resistance

2012 ◽  
Vol 62 ◽  
pp. 147-152 ◽  
Author(s):  
Z. Dong ◽  
X. Peng ◽  
Y. Guan ◽  
L. Li ◽  
F. Wang
Keyword(s):  
Oxidation Resistance ◽  
Composition And Structure ◽  
Optimization Of Composition

Process and Properties of Ultrafine Silver-Coated Electrolytic Copper Powders

2017 ◽  
Vol 898 ◽  
pp. 898-907
Author(s):  
De Rong Meng ◽  
Li Min Wang ◽  
Jing Guo Zhang ◽  
Qiang Hu ◽  
Li Gen Wang ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Reducing Agent ◽  
Silver Coating ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrolytic Copper ◽  
Dispersing Agent ◽  
Copper Powders ◽  
Composition And Structure

The ultrafine electrolytic copper powders were coated by silver using a combination of displacement reaction and reduction method, and the bimetallic core-shell powders with a 10wt.% addition of silver were obtained. The effects of concentration of complexing-dispersing agent and reducing agent on the silver coating layer were studied. The morphology, composition and structure of bimetallic core-shell powders were characterized by scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The oxidation resistance and electric conductivity of the coated powders were also investigated. The experimental results showed that the powders have a better oxidation resistance and higher conductivity using the complexing-dispersing agent of 10g/L EDTA-2Na and the reducing agent n of 30 g/L formaldehyde.

scholarly journals Zeolite-Based Materials for the Catalytic Oxidation of VOCs: A Mini Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Tianshan Xue ◽  
Li Yang
Keyword(s):  
Catalytic Oxidation ◽  
Functional Material ◽  
Monolithic Catalysts ◽  
Composition And Structure ◽  
Optimization Of Composition

Catalysts for VOCs combustion have been widely studied and zeolite-based materials and have been structured to meet the need of particle use in this field. This review summarized several new trends in zeolite-based catalysts for VOCs catalytic oxidation. Intensive effort has been devoted to the optimization of composition and structure of catalysts, abatement of CVOCs, design of zeolite-based monolithic catalysts and adsorbent/catalyst bi-functional material. The suggestions for further work here presented are put forward based on the collation of recently published papers.

Optimization of Composition and Structure of Metal‐Hydride Electrodes

1994 ◽  
Vol 141 (7) ◽  
pp. 1747-1750 ◽  
Author(s):  
Konstantin Petrov ◽  
Abbas A. Rostami ◽  
Arnaldo Visintin ◽  
Supramaniam Srinivasan
Keyword(s):  
Metal Hydride ◽  
Composition And Structure ◽  
Structure Of Metal ◽  
Metal Hydride Electrodes ◽  
Optimization Of Composition

Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

1972 ◽  
Vol 30 ◽  
pp. 524-525
Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit
Keyword(s):  
Electron Microscopy ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Substrate Surface ◽  
Morphological Features ◽  
Thermally Induced ◽  
Oxide Spallation ◽  
Oxidation Resistant ◽  
Induced Stresses ◽  
Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

Off-axis electron holography applied to the study of interfaces

1992 ◽  
Vol 50 (1) ◽  
pp. 244-245
Author(s):  
J.K. Weiss ◽  
M. Gajdardziska-Josifovska ◽  
M. R. McCartney ◽  
David J. Smith
Keyword(s):  
Electric Fields ◽  
Resolution Enhancement ◽  
Interfacial Structure ◽  
Atomic Scale ◽  
Bulk Property ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Composition And Structure ◽  
Chemical Segregation ◽  
Diffraction Effects

Interfacial structure is a controlling parameter in the behavior of many materials. Electron microscopy methods are widely used for characterizing such features as interface abruptness and chemical segregation at interfaces. The problem for high resolution microscopy is to establish optimum imaging conditions for extracting this information. We have found that off-axis electron holography can provide useful information for the study of interfaces that is not easily obtained by other techniques.Electron holography permits the recovery of both the amplitude and the phase of the image wave. Recent studies have applied the information obtained from electron holograms to characterizing magnetic and electric fields in materials and also to atomic-scale resolution enhancement. The phase of an electron wave passing through a specimen is shifted by an amount which is proportional to the product of the specimen thickness and the projected electrostatic potential (ignoring magnetic fields and diffraction effects). If atomic-scale variations are ignored, the potential in the specimen is described by the mean inner potential, a bulk property sensitive to both composition and structure. For the study of interfaces, the specimen thickness is assumed to be approximately constant across the interface, so that the phase of the image wave will give a picture of mean inner potential across the interface.

Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

1994 ◽  
Vol 52 ◽  
pp. 538-539
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J.-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Elevated Temperatures ◽  
Matrix Material ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

Specific composition and structure of population phytopathogens of vegetable crops

2019 ◽  
Vol 326 (3) ◽  
pp. 76-78
Author(s):  
V.L. Nalobova ◽  
◽  
N.S. Opimah ◽  
M.V. Nalobova ◽  
I.V. Haponenka ◽  
...  
Keyword(s):  
Vegetable Crops ◽  
Specific Composition ◽  
Composition And Structure ◽  
Structure Of Population

The diatoms as a component of bottom algocenoses in the mouth of the Oka River

2019 ◽  
Author(s):  
Alexander G. Okhapkin ◽  
Tabet Hhedairia
Keyword(s):  
Water Temperature ◽  
Preliminary Estimation ◽  
Composition And Structure

The preliminary estimation of composition and structure of diatoms in the benthos of the Oka River allowed to determine the clear spatiotemporal confinedness of structure in such communities of them which has the most diverse composition in the low water period while water temperature decreasing.

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