Investigation of Ultrasonic Electroplating Ni-P Coatings on Nd-Fe-B Permanent Magnet

2011 ◽  
Vol 284-286 ◽  
pp. 980-983
Author(s):  
Fei Fei Wang ◽  
Li Li
Keyword(s):  
Corrosion Resistance ◽  
Permanent Magnet ◽  
Technological Process ◽  
Immersion Test ◽  
Nacl Solution ◽  
Adhesion Test ◽  
Ultrasonic Agitation ◽  
Uniform Microstructure ◽  
Alloy Deposit ◽  
Poor Adhesion

In order to improve the corrosion resistance of Nd-Fe-B, the new technological process is done which involves electroplating Ni–P alloys with ultrasonic. The influence of ultrasonic on electroplating Ni–P alloy on Nd-Fe-B was studied by using microscope, adhesion test and NaCl solution immersion test. The results showed that the Ni–P alloy deposit on Nd-Fe-B is rough and has poor adhesion without ultrasonic agitation; however, the Ni–P alloy deposit on Nd-Fe-B with ultrasonic agitation has more compact and uniform microstructure, smoother morphology. At the same time, the adhesion and corrosion resistance are greatly enhanced.

Study on Ultrasonic Electroforming Ni-P Coatings on NdFeB Permanent Magnet

2012 ◽  
Vol 535-537 ◽  
pp. 1275-1278
Author(s):  
Li Li ◽  
Xiang Cheng ◽  
Feng Shi Yin
Keyword(s):  
Corrosion Resistance ◽  
Nacl Solution ◽  
Adhesion Test ◽  
Ndfeb Magnet ◽  
Ultrasonic Agitation ◽  
New Process ◽  
Strong Adhesion ◽  
Alloy Deposit ◽  
Ndfeb Permanent Magnet ◽  
Poor Adhesion

In order to improve the corrosion resistance of sintered NdFeB magnet, experiments are done by the new process which involves ultrasonic electroforming Ni–P alloys. The influence of ultrasonic on electroforming Ni–P alloy on NdFeB was studied by using microscope, adhesion test and NaCl solution immersion test.The results showed that the Ni–P alloy deposit on NdFeB is rough and has poor adhesion without ultrasonic agitation; However, the Ni–P alloy deposit on NdFeB with ultrasonic agitation has the following advantages: uniform and smooth deposit grains, strong adhesion and good corrosion resistance.

Surface Modification on Magnesium Alloys by Coating with Magnesium Fluorides

2005 ◽  
Vol 475-479 ◽  
pp. 505-508 ◽  
Author(s):  
T. Ohse ◽  
Harushige Tsubakino ◽  
Atsushi Yamamoto
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Az31 Alloy ◽  
Immersion Test ◽  
Low Ph ◽  
Nacl Solution ◽  
Filiform Corrosion ◽  
A New Technique

A new technique has been developed for improving corrosion resistance on magnesium alloys. Specimens of AZ31 magnesium alloy were dipped into molten salt of NaBF4 at 723 K for various times, and then cooled, rinsed with water, and dried in air. Corrosion resistance in the surface treated specimens was evaluated by salt immersion test using 1 % NaCl solution as a time for occurring filiform corrosion. On an un-treated AZ31 alloy, the time for starting the filiform corrosion was about 1.2 ks, while on the surface treated specimen, the time was prolonged into about 1300 ks. Moreover, the surface treated specimen showed corrosion resistance in low pH solutions, such as 1 % HNO3 and HCl solutions.

Effect of Coating Thickness on the Corrosion Behavior of Galvanized Steel in 3.5 % NaCl Solution

2021 ◽  
Vol 882 ◽  
pp. 35-49
Author(s):  
A.D. Vishwanatha ◽  
Bijayani Panda ◽  
J.N. Balaraju ◽  
Preeti Prakash Sahoo ◽  
P. Shreyas
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Coating Thickness ◽  
Electrochemical Impedance ◽  
Immersion Test ◽  
Carbon Steels ◽  
Galvanized Steel ◽  
Uniform Corrosion ◽  
Nacl Solution

Corrosion behavior of three carbon steels with increasing galvanized coating thickness of 5.6, 8.4 and 19.2 μm named as T1, T2 and T3, respectively, was studied by immersion test, potentiodynamic polarization and electrochemical impedance spectroscopy in freely aerated 3.5% NaCl solution. The major phase in the corrosion product of all the samples after immersion test was found to be zincite, as determined by X-Ray Diffraction and Fourier Transform Infrared Spectroscopy techniques. The corrosion product on sample T1was well adhered and was compact in most regions. Samples T2 and T3 showed porous and non-adherent growth of corrosion product. Corrosion rates were found to increase with increasing coating thickness. The impedance provided by the coating as well as the substrate was the highest for the sample with thinnest coating (T1). The early exposure of the underlying steel in sample T1 resulted in higher corrosion resistance, which was probably due to the combined effect of zinc corrosion products and Fe-Zn alloy layer. Higher amount of protective γ-FeOOH as well as compact corrosion product could have also improved the corrosion resistance of sample T1. Although the average uniform corrosion resistance was higher for T1, the localized pitting corrosion was also observed, probably due to the thin galvanized layer.

The Corrosion Resistance of the Mg-Al-Ca-Sr Sand Casting Magnesium Alloys

2012 ◽  
Vol 326-328 ◽  
pp. 255-260 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń ◽  
Joanna Michalska ◽  
Michal Stopyra
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
Immersion Test ◽  
Corrosion Layer ◽  
Sand Casting ◽  
Nacl Solution ◽  
Effective Barrier ◽  
Corrosion Rates

In this paper, the corrosion resistance of two sand-casting creep resistant magnesium alloys Mg-9Al-1.5Ca-0.3Sr and Mg-9Al-2.2Ca-0.8Sr in the salt environment has been investigated. Specimens of each alloy has been immersed in 3.5% NaCl solution at room temperature and successively taken out after 1, 2, 4, 5 and 9 days. After immersion test, the microstructure and the appearances of the corroded structure were examined. The corrosion rates of both investigated alloys increased lineally with increasing the exposure time in both solutions. Mg-9Al-1.5Ca-0.3Sr alloy exhibits the higher corrosion rate during the immersion test than Mg-9Al-2.2Ca-0.8Sr. The corrosion layer of both alloys consists of MgO, MgOH and phases containing Cl, Na, Al and Ca. The increase of Ca content in the Mg-9Al-2.2Ca-0.8Sr alloy improved the corrosion resistance due to the formation of the reticular (Mg,Al)2Ca phase, which acted as an effective barrier against corrosion.

Effect of Chromium Addition on Damping Capacity, Mechanical Property, and Corrosion Resistance of Fe-18%Mn Alloy

2006 ◽  
Vol 319 ◽  
pp. 73-78 ◽  
Author(s):  
Jung Chul Kim ◽  
Seung Han Baik ◽  
Joong Hwan Jun ◽  
Young Kook Lee
Keyword(s):  
Mechanical Property ◽  
Tensile Strength ◽  
Corrosion Resistance ◽  
Immersion Test ◽  
Damping Capacity ◽  
Nacl Solution ◽  
Chromium Addition ◽  
Cr Content ◽  
Cr Addition ◽  
Start Temperature

Effect of Cr addition on damping capacity, mechanical property, and corrosion resistance of Fe-18%Mn martensitic alloy has been studied. Martensite start temperature (Ms) of the alloy decreases linearly from 150 to 25 with increasing Cr content up to 15%. The damping capacity decreases gradually from 27 to 23% in SDC with increasing Cr content from zero to 10%, and decreases rapidly with further Cr content. The tensile strength of the alloy maintains a level of 60 / regardless of Cr content with an elongation of 20 to 25%. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy with a lesser decrease in damping capacity is about 10%.

Comparative Study of Microstructural and Corrosion Characteristics of Excimer Laser-Melted AA2124-T4 and AA6061-T4 Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 235-240 ◽  
Author(s):  
Dai Shu Qian ◽  
Zhu Liu
Keyword(s):  
Corrosion Resistance ◽  
Excimer Laser ◽  
Corrosion Behaviour ◽  
Electrochemical Techniques ◽  
Compositional Analysis ◽  
Laser Pulses ◽  
Immersion Test ◽  
Nacl Solution ◽  
Intermetallic Particles ◽  
Melted Layer

A KrF excimer laser was introduced for laser surface melting (LSM) of the aluminium alloys AA2124-T4 and AA6061-T4. The microstructural and compositional analysis was conducted using SEM, low-angle XRD, and TEM; the corrosion behaviour of as-received (AR) and laser-treated (LT) samples was evaluated by electrochemical techniques and immersion test in a 3.5% NaCl solution. A melted layer consisting of a re-solidified layer with refined microstructure and dissolution of intermetallic particles (IMPs), and a thin film of aluminium oxides at the top, was formed after LSM for both alloys. The corrosion resistance of both alloys was improved after LSM. The results of immersion test showed different corrosion behaviour for LT AA2124 and LT AA6061. The delamination of the melted layer was observed for AA2124 but was not observed for AA6061 after exposure to 3.5% NaCl solution for 24 h. This was attributed to the formation of copper-rich segregation bands in the melted layer of AA2124 due to higher content of copper in AA2124 than AA6061. A significant number of micro-pores were present in the melted layer for AA2124 treated with high number of laser pulses, leading to the decrease of the corrosion resistance.

scholarly journals High-Performance Mg–Al–Bi Alloy Anode for Seawater Batteries and Related Mechanisms

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1362
Author(s):  
Changqing Wu ◽  
Xu Meng ◽  
Wei Wang
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Performance ◽  
Electrochemical Properties ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Immersion Test ◽  
Utilization Efficiency ◽  
Discharge Process ◽  
Nacl Solution ◽  
Galvanostatic Discharge

Bi, a group 15 element, was added to magnesium alloys and applied to seawater batteries in marine operating machinery to improve the electrochemical performance and corrosion resistance of the battery. The electrochemical properties of as-cast pure Mg, Mg–8Al, and Mg–8Al–xBi alloy anodes in 3.5% NaCl solution were researched. Electrochemical impedance spectroscopy and an immersion test in 3.5% NaCl solution show that the Mg–8%Al–0.4%Bi alloy provides better corrosion resistance than Mg and the Mg–8Al alloy. The galvanostatic discharge results show that the Mg–8%Al–0.4%Bi alloy revealed better electrochemical properties and utilization efficiency in 3.5% NaCl solution. The Mg17Al12 and BiOCl phases formed during the discharge process of the Mg–8%Al–0.4%Bi alloy play an important role in improving the electrochemical performance and utilization efficiency of the alloy.

Corrosion Resistance of Mo-Fe-Ti Alloy for Overpack in Simulating Underground Environment

2010 ◽  
Author(s):  
Toshiyasu Nishimura
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Selective Dissolution ◽  
Immersion Test ◽  
Ti Alloy ◽  
Nacl Solution ◽  
Β Phase ◽  
Heat Treated

In order to examine the application of Mo-Fe-Ti alloy for overpak, the corrosion resistance of heat-treated its alloys was investigated by Electrochemical impedance spectroscopy (EIS), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDAX). Considering the welding, the sample subjected to solution heat treatment (ST) had a single β phase and samples subjected to aging heat treatment at 600–700°C had a-phase precipitation in b-phase. EIS results showed that the corrosion resistance of the aging heat-treated samples was lower than that of the ST sample, but much higher than that of pure Ti in long term immersion test in 10% NaCl solution of pH 0.5 at 97°C which simulating the crevice solution. Laser micrographs of the aging heat-treated samples indicated that a-phase at the grain boundary and in the grain was selectively corroded and caused selective dissolution in NaCl solution. The results of TEM combined with EDAX analyses showed that there were b-phase matrix composed of 2.7 wt% of Mo and 4.8wt% of Fe, and a-phase composed of 0.7 wt% of Mo and 0.1 wt% of Fe in sample aged at 600°C. Thus, Mo-poor a-phase was selectively dissolved in in 10% NaCl solution of pH 0.5 at 97°C. In a result, the ST sample of only b-phase showed the highest resistance, and aging heat-treated samples containing a-phase (0.7 wt% of Mo) showed higher values than pure Ti in the corrosion test. Addition of Fe did not decrease the resistance of alloy in the case of ST condition. Moreover, as Fe was involved in b-phase with Mo which increased remarkably the corrosion resistance, the addition of Fe did not decrease the corrosion resistance of aging heat-treated Mo-Fe-Ti alloy. Finally, it was concluded that Mo-Fe-Ti alloy had excellent resistance for overpack in simulating underground environment.

Influence of Various Heat Treatment on Corrosion Resistance of As-Extruded Mg-9Li-3Al-2.5Sr Alloys

2014 ◽  
Vol 788 ◽  
pp. 41-44 ◽  
Author(s):  
Yuan Qing Yu ◽  
Xiao Dong Peng ◽  
Hong Yu Yi ◽  
Jun Wei Liu
Keyword(s):  
Corrosion Resistance ◽  
Intermetallic Compounds ◽  
Unit Volume ◽  
Aging Treatment ◽  
Corrosion Current ◽  
Immersion Test ◽  
Corrosion Process ◽  
Nacl Solution ◽  
Boundary Area ◽  
Solution Treated

The corrosion behavior of Mg-9Li-3Al-2.5Sr alloy, solution treated at 400°C for 3h with various aging temperature (Ta; Ta=75,100,125,150,175°C), was investigated in 3.5% NaCl solution by immersion test and polarization curve measurement. Experimental results suggest that the alloy aged at150°Cfor 6h exhibits the highest corrosion resistance while the alloy treated at 75°C for 6h presents lowermost corrosion resistance. The corrosion resistance of the alloy is related to the grain size and the distribution of Al4Sr compound. The segregation of intermetallic compounds can accelerate the corrosion process. It was found that duo to the proper solid-solution and aging treatment, intermetallic compounds were distributed evenly along the grain boundaries, which can reduce the corrosion rate and corrosion current. In addition,with the growth of grain, the decrease of the grain boundary area per unit volume lead to improvement of corrosion resistance of the alloys.

Corrosion Resistance of Mg-Li Alloys Subjected to Different Heat Treatment

2014 ◽  
Vol 1044-1045 ◽  
pp. 164-167
Author(s):  
D.R. Fang ◽  
F.F. Liu ◽  
Li Wei Quan ◽  
Jing Yang
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Aging Treatment ◽  
Immersion Test ◽  
Annealed Sample ◽  
Nacl Solution ◽  
Aged Sample ◽  
Electrochemical Impedance Spectroscopy Measurement ◽  
Cast Sample

Casting Mg-Li alloy samples were subjected to annealing and aging treatment respectively, and the corrosion resistance of different samples was investigated by immersion test and electrochemical impedance spectroscopy measurement in 3.5% NaCl solution. The results show that the corrosion resistance of the as-cast sample is the best,the aged sample is the second, and the annealed sample is the worst to resist corrosion.

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