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.

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.

Study of Corrosion Behavior of Conventional and Nanostructured WC-Co HVOF Sprayed Coats

2010 ◽  
Vol 64 ◽  
pp. 13-18 ◽  
Author(s):  
Shahin Khameneh Asl ◽  
Mohammad Reza Saghi Beyragh ◽  
Mahdi Ghassemi Kakroudi
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Heat Treating ◽  
Crystalline Phases ◽  
Chemical Test ◽  
Transmission Electron ◽  
Hvof Spray ◽  
Wear And Corrosion Resistance

Interest in nanomaterials has increased in recent years. This is due to the potential of size reduction to nanometric scale to provide properties of materials such as hardness, toughness, wear, and corrosion resistance. The current study is focused on WC-Co cermet coats, materials that are extensively used in applications requiring wear resistance. In this work, WC-17Co powder was thermally sprayed onto mild steel using High Velocity Oxy Fuel (HVOF) spray technique. The nanostructured specimen was produced from sprayed sample by heat-treating at 1100°C in a vacuum chamber. Their structures were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Polarization and electrochemical impedance spectroscopy (EIS) tests were performed on the both types of coated samples in 3.5% NaCl solution. The amorphous phase in WC-17Co coating was transformed to crystalline phases by heat treatment at high temperatures. The heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. Generation of these phases produced the nanostructured coating with better mechanical properties. Comparative electro chemical test results showed that, the heat treatment could improve corrosion resistance of the nanostructured WC-17Co coat than the as sprayed coats.

Wear and Corrosion Resistance of Electroless Nickel-Boron Coated Mild Steel

2010 ◽  
Vol 638-642 ◽  
pp. 846-851 ◽  
Author(s):  
Abdoul Fatah Kanta ◽  
Véronique Vitry ◽  
Fabienne Delaunois
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Electroless Nickel ◽  
Uncoated Steel ◽  
Wear And Corrosion ◽  
Heat Treated ◽  
Wear And Corrosion Resistance ◽  
Hardening Heat Treatment

Nickel-boron coatings were synthesized on mild steel by the electroless deposition method. Some of the coatings were submitted to a hardening heat treatment at 400°C during 1 hour in an atmosphere containing 95% Ar and 5% H2. Uncoated steel, treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the samples was investigated by the way of polarization and electrochemical impedance spectroscopy (EIS) and the influence of the heat treatment was observed.

Effect of KI on the Corrosion Resistance of Ni-P Electroless Plating Coating

2014 ◽  
Vol 633-634 ◽  
pp. 817-820
Author(s):  
Ping Liang ◽  
Yun Xia Zhang ◽  
Yan Hua Shi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Phosphorus Content ◽  
Electrochemical Impedance ◽  
Nacl Solution ◽  
Electroless Coating ◽  
Scanning Electron

To improve the corrosion resistance of Ni-P electroless coating, the KI was added in the electroless solution. The surface micrograph was observed using scanning electron microscopy (SEM), and the corrosion resistance of Ni-P coatings in 3.5%NaCl solution was examined by polarization curves and electrochemical impedance spectroscopy (EIS). The experimental results showed that KI reduced the amount of defects and the size of crystal grain of Ni-P coating, and the surface of Ni-P coating became more homogenous, smoother and compact by KI. In addition, the phosphorus content of Ni-P coating was increased by KI. These factors increased the ability to corrosion protection of Ni-P coating.

Characterization of Ni-P and Ni-P-Al2O3 Heat Treated Layers

2017 ◽  
Vol 1143 ◽  
pp. 26-31
Author(s):  
Lucica Balint ◽  
Gina Genoveva Istrate
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Composite Coatings ◽  
Treatment Temperature ◽  
Initial State ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Before And After

Research has shown the relationship among hardness, usage and corrosion resistance Ni-P-Al2O3 composite coatings on steel support heat treated. The electroless strips were heat treated at 200°C, 300°C, 400°C, 500°C and 600°C. Further studies on corrosion, hardness and usage revealed changes in properties, compared to the initial state, both on the strips coated with Ni-P and the ones coated with Ni-P-Al2O3 composite. The samples have been studied before and after the heat treatment via Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Analysis (EDX) and X-Ray Diffraction (XRD). The results show that untreated Ni-P layers exhibit strong corrosion resistance, while hardness and usage increase with heat treatment temperature, with a peak at 400 °C. Using suspended particles co-deposition, led to new types of layers, some with excellent hardness and usage properties. Corrosion resistance increase with heat treatment. Coating layers can be adjusted to the desired characteristics, by selecting proper parameters for the expected specific results.

scholarly journals Effect of Microstructure on Corrosion Behavior of WE43 Magnesium Alloy in As Cast and Heat-Treated Conditions

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1552
Author(s):  
Chenxi Yang ◽  
Nikhil Gupta ◽  
Hanlin Ding ◽  
Chongchen Xiang
Keyword(s):  
Heat Treatment ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Immersion Test ◽  
Adjacent Area ◽  
Protective Film ◽  
Nacl Solution ◽  
Rich Phase ◽  
Corrosion Reaction ◽  
Heat Treated

The improvement in corrosion resistance of WE43 was well realized by heat treatment. To study the influence of microstructure on the corrosion behavior of WE43 in as-cast and heat-treated conditions, an immersion test was employed with as-cast and heat-treated samples in the 3.5% NaCl solution. The corrosion rate and change of morphology were recorded and the corrosion behavior was further investigated by scanning electron microscopy (SEM). The results indicated that the corrosion rate of the WE43 alloy decreased after heat treatment. It was observed that the eutectic gradually damages the protective film on the surface of the as-cast WE43 in the process of corrosion, which further increases the corrosion rate. The Zr-rich phase formed a domed structure resulting in the adjacent area being further corroded. The Y-rich phase has little effect on the corrosion reaction.

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.

scholarly journals Corrosion Resistance of Heat-Treated Ni-W Alloy Coatings

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1172
Author(s):  
Magdalena Popczyk ◽  
Julian Kubisztal ◽  
Andrzej Szymon Swinarew ◽  
Zbigniew Waśkiewicz ◽  
Arkadiusz Stanula ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Active Surface ◽  
Active Surface Area ◽  
X Ray Diffraction ◽  
Kelvin Probe ◽  
Research On Evaluation ◽  
Heat Treated ◽  
Electrochemically Active

The paper presents research on evaluation of corrosion resistance of Ni-W alloy coatings subjected to heat treatment. The corrosion resistance was tested in 5% NaCl solution by the use of potentiodynamic polarization technique and electrochemical impedance spectroscopy. Characteristics of the Ni-W coatings after heat treatment were carried out using scanning electron microscopy, scanning Kelvin probe technique and X-ray diffraction. Suggested reasons for the improvement of properties of the heat treated Ni-W coating, obtained at the lowest current density value (125 mA∙cm−2), are the highest tungsten content (c.a. 25 at.%) as well as the smallest and the most homogeneous electrochemically active surface area.

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.

Effect of Heat Treatment of AZ91 Magnesium Alloy on the Electroless Ni-P Deposition

2018 ◽  
Vol 1148 ◽  
pp. 122-127 ◽  
Author(s):  
Charu Singh ◽  
S.K. Tiwari ◽  
Raghuvir Singh
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Electrochemical Impedance ◽  
Cast Alloy ◽  
Az91 Magnesium Alloy ◽  
Heat Treated ◽  
Az91 Magnesium ◽  
Electroless Ni

Magnesium alloys are excellent choice for automobile, aerospace, and computer components owing to their light weight, unique physical and mechanical properties. However, poor corrosion resistance has restricted their applications in aggressive environments. The surface coating is one of the viable options to reduce the susceptibility of magnesium alloys to corrosion. The present study focuses on the effect of heat treatment of AZ91 magnesium alloy, for different durations at 400 °C, prior to electroless Ni-P deposition on corrosion resistance. The microstructure and elemental analysis of the heat-treated specimens are performed using SEM and EDS techniques respectively. It is observed that the duration of heat treatment has a significant effect on the surface morphology and microstructure of the alloy. The precipitates in the cast alloy (enriched with Mg and Al) fragmented and the transformed into a new Al and Zn rich phase, after 12 h heat treatment. The dissolution of precipitates, however, observed on heating further to 24 h and exhibited relatively a lesser corrosion current density. The dense electroless Ni-P deposition is formed on the alloy heat treated for 24 h. The corrosion behavior of the single Ni-P layer on the heat treated (for 12 h) and untreated alloy show a marked deterioration, as investigated by the anodic polarization and electrochemical impedance spectroscopy (EIS) techniques. Relatively a better corrosion performance is seen for the double-layer Ni-P deposition. The duplex layer coatings on the as cast and heat treated for 24 h at 400 °C substrates showed an improved corrosion resistance compared to that on the 12 h heat treated substrate.

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