Effect of Current Density on Microstructure and Corrosion Resistance of Ni–W Alloy Coatings

2014 ◽  
Vol 1033-1034 ◽  
pp. 1241-1244
Author(s):  
Yi Xiao ◽  
Qiong Yu Zhou ◽  
Jian Hui Fang ◽  
Qing Dong Zhong
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Current Density ◽  
Alloy Coating ◽  
Critical Value ◽  
Current Densities ◽  
Electroplated Coating ◽  
Deposition Current Density ◽  
Scanning Electron

Ni-W alloy coating was electroplated on the surface of mild steel and the effect of current density on its corrosion behavior was evaluated in this paper. The microstructure of the coatings were scanning electron microscopy (SEM) Polarization techniques have been used to investigate the corrosion behavior in 3.5wt.% NaCl. The results showed that the surface morphology of the coatings is strongly influenced by the deposition current density. And the increased of current densities is benefit for the Ni-W coating from0.5 to 4A/dm2, and the critical value of current densities is 4A/dm2, the corrosion resistance of electroplated coating present better worse when current densities exceeds the critical value or more.

Research on Preparation and Properties of Al-Mn Alloy Coating in NaCl-KCl-AlCl3-NdCl3 Molten Salts

2011 ◽  
Vol 121-126 ◽  
pp. 335-339
Author(s):  
Xian Jin Yu ◽  
Li Peng Zhang ◽  
Zhi Wei Ge ◽  
Yun Hui Dong ◽  
Dang Gang Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Molten Salts ◽  
Alloy Coating ◽  
Surface Coatings ◽  
X Ray Diffraction ◽  
Pitting Potential ◽  
X Ray ◽  
Scanning Electron

Al-Mn alloy coatings were electrodeposited on an iron substrate from AlCl3-NaCl-KCl low-temperature molten salts with anhydrous MnCl2 enhanced by the addition of NdCl3.The microstructure and properties of the Al-Mn alloy coatings were investigated, and scanning electron microscopy, X-ray diffraction, and polarization curves were used to determine the composition, surface morphology, phase structure, and corrosion resistance of the obtained deposits. The results show that the surface coatings were smooth, and that the crystallites were dense and uniform when 0.23 wt% NdCl3 was added to the molten salt. An amorphous mixture of Al and Al6Mn was obtained. NdCl3 enhanced the corrosion resistance and increased the hardness of the single amorphous phase alloys. The pitting potential of the coating was approximately −1.04V, and its hardness was 392 kgf/mm2.

Corrosion Analysis of AZ61 Alloy with Different Level of Ca Addition and Aging

2014 ◽  
Vol 592-594 ◽  
pp. 821-825
Author(s):  
S. Manivannan ◽  
M.P. Sathishkumar ◽  
S.P. Kumaresh Babu ◽  
Srinivasan Sundarrajan
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Microstructural Change ◽  
Nacl Solution ◽  
Ca Addition ◽  
Polarization Technique ◽  
Potentiostatic Polarization ◽  
Scanning Electron

The corrosion behavior of AZ61 alloyed with 0.5, 1.0, 1.5 and 2.0% Ca were studied by potentiostatic polarization technique in 3.5wt. % NaCl solution and the further effect of corrosion behavior have been studied after aging at different temperature in a controlled environment.The results show that the calcium addition enhances the corrosion resistance.Simultaneously when the alloy is aged at 180°C, the corrosion resistance has improved. This study also reveals the interesting microstructural change that isresponsible for the improved corrosion resistance. Themicrostructural characterization of this alloy was studied using Optical and Scanning Electron Microscopy (SEM).

Assessment of the Corrosion Behavior of Nd-Fe-B Magnets Used in Dentistry

2008 ◽  
Vol 587-588 ◽  
pp. 57-61
Author(s):  
E.A. Martins ◽  
Isolda Costa ◽  
J.L. Rossi ◽  
Hercílio G. De Melo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Permanent Magnets ◽  
Electrochemical Impedance ◽  
Test Solution ◽  
Potentiodynamic Polarization Curves ◽  
Diffusion Controlled ◽  
Scanning Electron

Permanent magnets based on intermetallic compounds are employed in dentistry to fix dental prosthesis. However, these materials are very sensitive to corrosion. In this study the corrosion behavior of a sintered commercial Nd-Fe-B magnet has been investigated at neutral pH in a phosphate buffered solution (PBS). With this aim demagnetized specimens were immersed in the test solution and their corrosion behavior were monitored at increasing test times by means of electrochemical impedance spectroscopy ( EIS ), potentiodynamic polarization curves and surface observation by scanning electron microscopy ( SEM ). Experimental results indicated that the corrosion resistance is seriously affected in this solution. Moreover, no decrease in the intensity of the corrosive attack was verified during test periods of up 4 hours. Impedance results have indicated the occurrence of diffusion controlled phenomenon, likely linked to the presence of pores in the magnet microstructure.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Influence of Fly Ash on Corrosion Resistance of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 325 ◽  
pp. 181-187
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Fly Ash ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Zones ◽  
Refractory Ceramics ◽  
Scanning Electron

This article examines the influence of fly ash on corrosion resistance of refractory forsterite-spinel ceramics by molten iron as a corrosive medium. Fly ash in comparison with alumina were used as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1550°C for 2 hours. Samples were characterized by X-ray diffraction analysis and thermal dilatometric analysis. Crucibles were then made from the fired ceramic mixtures and fired together with iron at its melting point of 1535°C for 5 hours. The corrosion resistance was evaluated by scanning electron microscopy on the transition zones between iron and ceramics. Mixtures with increased amount of spinel had higher corrosion resistance and mixtures with fly ash were comparable to mixtures with alumina in terms of corrosion resistance and refractory properties.

scholarly journals Effect of deposition current density and annealing temperature on the microstructure and magnetic properties of nanostructured Ni-Fe-W-Cu alloys

2019 ◽  
Vol 51 (2) ◽  
pp. 209-221 ◽  
Author(s):  
Milica Spasojevic ◽  
Dusan Markovic ◽  
Miroslav Spasojevic ◽  
Zoran Vukovic ◽  
Aleksa Maricic ◽  
...  
Keyword(s):  
Current Density ◽  
Amorphous Matrix ◽  
Ammonium Citrate ◽  
High Current ◽  
Cathodic Polarization Curve ◽  
Cu Alloy ◽  
Powder Particles ◽  
Current Densities ◽  
Deposition Current Density ◽  
Microstructure And Magnetic Properties

Ni-Fe-W-Cu alloy powders were obtained by electrodeposition from an ammonium citrate bath at current densities ranging between 70 and 600 mA cm-2. As the deposition current density increased, the contents of Fe and W in the alloy increased, and those of Ni and Cu decreased. The total cathodic polarization curve was recorded, and partial polarization curves for Ni, Fe and W deposition and hydrogen evolution were determined. The current efficiency of alloy deposition was measured. The powders contained an amorphous matrix and FCC nanocrystals of the solid solution of Fe, W and Cu in Ni. At high current densities, small-sized nanocrystals exhibiting high internal microstrain values were formed. Powder particles were dendrite- and cauliflower-shaped. The dendrites had a large number of secondary branches and higher-order branches containing interconnected globules. The density of branches was higher in particles formed at high current densities. The powders formed at high current densities exhibited higher magnetization. Annealing at temperatures up to 460?C resulted in structural relaxation, accompanied by an increase in magnetization. At temperatures above 460?C, amorphous matrix crystallization and FCC crystal growth took place, accompanied by a decrease in magnetization.

Electrochemical Corrosion Behavior of Different Graphite Shapes Cast Irons in Acidic Solution

2014 ◽  
Vol 906 ◽  
pp. 275-282
Author(s):  
Zhu Huan Yu ◽  
Jun Feng Qiang ◽  
Hui Lu Li
Keyword(s):  
Electron Microscopy ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Driving Force ◽  
Acidic Solution ◽  
Electrochemical Corrosion ◽  
White Iron ◽  
Cast Irons ◽  
The Matrix ◽  
Electrochemical Corrosion Behavior

The effect of graphite shapes on the electrochemical corrosion behavior of cast iron was studied by means of weight loss tests, electrochemical measurements and electron microscopy. It was found that the electrochemical corrosion behavior of graphite is significantly different from one other, and the corrosive potential difference between carbide ad the matrix is the main driving force of the different phase corrosions. Among them, the center A type and edge D type graphite exhibited the highest corrosion resistance. The corrosion of white iron is worst, because there are so many type carbides in white iron and so there is an obvious tendency to produce micro-cell in white iron.

Study of Corrosion Behavior of Friction Surfacing AA6351 Aluminium Alloy Coating on AISI 1020 Low Carbon Steel

2020 ◽  
Vol 1012 ◽  
pp. 401-406
Author(s):  
Carlos Trivellato de Carvalho Filho ◽  
Pedro Paiva Brito
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Carbon Steel ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Low Carbon Steel ◽  
Alloy Coating ◽  
Low Carbon ◽  
Friction Surfacing ◽  
Finishing Process

In the present work, the friction surfacing process was applied to manufacture aluminum alloy (AA6351) coatings on low carbon steel (AISI 1020) substrates. After friction surfacing the AA6351 deposited coatings were submitted to two finishing process in order to adjust surface roughness: milling and milling followed by sanding. The corrosion behavior of the two finishing process was compared with the as-deposited condition in order to determine the influence of surface roughness on the corrosion resistance of friction surfacing coatings. The corrosion behavior was examined by electrochemical impedance spectroscopy and potentiodynamic polarization in a 3.5wt.%NaCl solution containing naturally dissolved O2. The results obtained indicated that the elevated surface roughness observed in the as-deposited condition led to relatively lower corrosion resistance in comparison, with lower values for polarization resistance and more anodic corrosion potential.

The study of proventricular micromorphological characterization of ten Grylloidea species (Orthoptera: Grylloidea) from China

Zootaxa ◽  
2011 ◽  
Vol 2906 (1) ◽  
pp. 52
Author(s):  
XIAOQIANG LI ◽  
BINGZHONG REN ◽  
YUTING ZOU ◽  
JIAN ZHANG ◽  
YINLIANG WANG
Keyword(s):  
Electron Microscopy ◽  
Clustering Analysis ◽  
Feeding Habits ◽  
Critical Value ◽  
Morphological Characterization ◽  
Species Relationships ◽  
Future Studies ◽  
Selection Of ◽  
Scanning Electron

The present study compares the proventricular morphology, analyzed under optic microscope and scanning electron microscopy (SEM), among ten Grylloidea species. The result showed that the size of proventriculus was of critical value. Internally, the main differences were the number of sclerotized appendix (sa), middle denticles (md) and lateral denticles (ld), and the structure of lateral teeth (lt). In addition, we analyzed the crickets’ feeding habits and note that the the proventriculus possesses highly sclerotized projections which act in the selection of victuals. The morphology of proventriculus is closely related to feeding habits. A clustering analysis of seven features of the proventriculus was constructed. It revealed that the proventriculus had significance for taxonomy and species relationships. Observations on morphological characterization of proventricular morphology will be useful in future studies of the feeding habits and phylogeny of crickets.

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