Corrosion Behavior of some Sintered CuNi Alloys – Preliminary Laboratory Data

2008 ◽  
Vol 38 ◽  
pp. 229-237 ◽  
Author(s):  
Adriana Sorcoi ◽  
Raluca Fako ◽  
S. Cojocaru
Keyword(s):  
Corrosion Behavior ◽  
Laboratory Data ◽  
Sintered Specimen ◽  
Specimen Surface ◽  
Alloying Element ◽  
Corrosion Tests ◽  
Corrosion Mechanisms ◽  
Sintered Alloys ◽  
Manufacturing Parameters

The paper aims to discuss some aspects on corrosion behavior of specimens from sintered CuNi alloys (e.g. Cu90Ni10; Cu70Ni30). The above mentioned specimens were manufactured by dissimilar laboratory routes: from alloyed powders, from elementary powders and from mixtures consisting of Cu80Ni20 alloy and an alloying element. Research aims to establish the manufacturing parameters influence on sintered specimens characteristics (density, porosity, microstructure features) in order to correlate them with corrosion tests laboratory data. There were investigated the corrosion mechanisms in relation with macro- and microstructure properties of the sintered specimen surface. For comparison purposes, it is intended to extend the analysis to Cu60Ni40 and Cu80Ni20 sintered alloys.

scholarly journals Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Hao-Hsiang Huang ◽  
Fan-Bean Wu ◽  
Jyh-Wei Lee ◽  
Li-Chun Chang
Keyword(s):  
Corrosion Behavior ◽  
Single Layer ◽  
Phase Identification ◽  
Bilayer Thickness ◽  
Ni Alloy ◽  
Nitride Coatings ◽  
Superior Corrosion Resistance ◽  
Corrosion Mechanisms ◽  
Steel Substrates ◽  
Crn Coatings

The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100) silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of . The single-layer Ni-alloy and CrN coatings deposited at were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the and values ranged from –0.64 to –0.33 V and to  A/, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

Computational and Experimental Insights into the Role of Acidic Molecules on the Corrosion Behavior on 7A46 Aluminum Alloy

2021 ◽  
Vol 21 (4) ◽  
pp. 2221-2233
Author(s):  
Yaru Liu ◽  
Qinglin Pan ◽  
Xiangdong Wang ◽  
Ye Ji ◽  
Qicheng Liu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Corrosion Behavior ◽  
First Principles ◽  
First Principles Calculations ◽  
Corrosive Media ◽  
Corrosion Depth ◽  
Corrosion Mechanisms ◽  
Nanoscale Level

The corrosion mechanisms for different corrosive media on the aged 7A46 aluminum alloy were systematically investigated at nanoscale level. The combination of empirical intergranular and exfoliation corrosion behavior was employed, and coupled with first-principles calculations. Results revealed that the dispersed distribution of matrix precipitates (MPs) leads to the enhancement of the corrosion resistance pre-ageing (PA) followed by double-ageing (PA-DA) alloy. The deepest corrosion depth of PA-DA alloy was in hydrochloric acid, and the calculation result demonstrates that the passivation effect in combination with the accumulation of corrosion products in nitric acid protect the PA-DA alloy from further corrosion.

High-Temperature Corrosion of Ni3Al+ 2.9%Cr Alloy in Ar-0.2%SO2 Gas

2018 ◽  
Vol 775 ◽  
pp. 441-447
Author(s):  
Dong Bok Lee ◽  
Min Jung Kim ◽  
Gyu Chul Cho ◽  
Soon Young Park ◽  
Poonam Yadav
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Kirkendall Effect ◽  
High Temperature Corrosion ◽  
Scale Spallation ◽  
Corrosion Tests ◽  
Cooling Period ◽  
Corrosion Kinetics ◽  
Period 2

The high-temperature corrosion behavior of Ni3Al+2.9 wt% Cr alloy was studied in SO2-containing environment. Corrosion tests were carried out at 900, 1000, and 1100 °C for 100 h in atmospheric Ar-0.2% SO2 gas. The alloy corroded relatively slowly due mainly to formation of Al2O3 in the scale. Its corrosion kinetics deviated from the parabolic corrosion rate law to a certain extent owing to ensuing scale spallation. This was attributed to (1) stress generated during scaling and the subsequent cooling period, (2) voids that formed due to the Kirkendall effect, and (3) incorporation of sulfur in the scale. The scale that formed after corrosion at 900 °C consisted of the outer NiO scale, middle NiAl2O4 scale, and inner Al2O3 scale. The increased corrosion rate at 1000 and 1100 °C led to formation of the outer NiO scale, and inner Al2O3 scale.

Corrosion Tests of Zircaloy Hull Waste to Confirm Applicability of Corrosion Model and to Evaluate Influence Factors on Corrosion Rate under Geological Disposal Conditions

2014 ◽  
Vol 1665 ◽  
pp. 195-202 ◽  
Author(s):  
Osamu Kato ◽  
Hiromi Tanabe ◽  
Tomofumi Sakuragi ◽  
Tsutomu Nishimura ◽  
Tsuyoshi Tateishi
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Pure Water ◽  
Influence Factors ◽  
Spent Fuel ◽  
Geological Disposal ◽  
Corrosion Tests ◽  
Temperature Range ◽  
Corrosion Rates ◽  
Temperature Ranges

ABSTRACTCorrosion behavior is a key issue in the assessment of disposal performance for activated waste such as spent fuel assemblies (i.e., hulls and end-pieces) because corrosion is expected to initiate radionuclide (e.g., C-14) leaching from such waste. Because the anticipated corrosion rate is extremely low, understanding and modeling Zircaloy (Zry) corrosion behavior under geological disposal conditions is important in predicting very long-term corrosion. Corrosion models applicable in the higher temperature ranges of nuclear reactors have been proposed based on considerable testing in the 523−633 K temperature range.In this study, corrosion tests were carried out to confirm the applicability of such existing models to the low temperature range of geological disposal, and to examine the influence of material, environmental, and other factors on corrosion rates under geological disposal conditions. A characterization analysis of the generated oxide film was also performed.To confirm applicability, the corrosion rate of Zry-4 in pure water with a temperature change from 303 K to 433 K was obtained using a hydrogen measuring technique, giving a corrosion rate for 180 days of 8 × 10-3 μm/y at 303 K.To investigate the influence of various factors, corrosion tests were carried out. The corrosion rates for Zry-2 and Zry-4 were almost same, and increased with a temperature increase from 303 K to 353 K. The influence of pH (12.5) compared with pure water was about 1.4 at 180 days at 303 K.

Corrosion of Si3N4-Ceramics in Acids and Basics

2006 ◽  
Vol 45 ◽  
pp. 148-155 ◽  
Author(s):  
Jochen Schilm ◽  
Mathias Herrmann ◽  
G. Michael
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Aqueous Media ◽  
Structural Features ◽  
Boundary Phase ◽  
The Subject ◽  
Corrosion Mechanisms ◽  
Si3n4 Ceramics ◽  
Made In

The corrosion behavior of silicon nitride materials in aqueous media strongly depends on the composition and amount of the grain boundary. But there exist no systematic investigations of the relation between the corrosion behavior and the composition and amount of the grain-boundary phase. The subject of this study is based on the evaluation of the corrosion mechanisms of Si3N4 ceramics and YSiAlON glasses, both with defined and characterized compositions, in acidic and basic environments with different concentrations. Special effort has been made in describing the compositions of grain boundary phases in the sintered Si3N4 ceramics. A model to describe structural features of YSiAlON-glasses was developed which allows the correlation of the corrosion behavior of the ceramics and the glasses with their compositions. In combination with SEM and TEM investigations it became possible to give structural reasons for the different observed corrosion mechanisms.

scholarly journals Corrosion Resistance of Al/SiC Laser Cladding Coatings on AA6082

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 673
Author(s):  
Ainhoa Riquelme ◽  
Pilar Rodrigo ◽  
María Dolores Escalera-Rodríguez ◽  
Joaquín Rams
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Laser Cladding ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
The Matrix ◽  
Corrosion Mechanisms ◽  
Silicon Carbide Particles ◽  
Carbide Particles

Aluminum matrix composites reinforced with silicon carbide particles (SiCp) were deposited by laser cladding on AA6082 aluminum alloy. Different compositions of the matrix of the composites coating were used and different amounts of Si and Ti were added to a base of Al-12Si in order to control the reactivity between molten aluminum and SiCp during laser cladding. The corrosion behavior of the coatings deposited was evaluated in 3.5 wt.% NaCl solution using gravimetric analyses and electrochemical polarization tests. The corrosion products observed were Al(OH)3 and Al2O3, and they formed a layer that limited the evolution of corrosion. However, the presence of discontinuities in it reduced the corrosion resistance of the coating. The corrosion mechanisms were different depending on the coating composition. The addiction of Ti to the alloy allowed for better corrosion behavior for the composite coating than that of the aluminum substrate.

The corrosion behavior of chromated AA2024 aluminum alloy in 3.5% NaCl solution

2019 ◽  
Vol 66 (6) ◽  
pp. 879-887 ◽  
Author(s):  
Yong Zhou ◽  
Pei Zhang ◽  
Jinping Xiong ◽  
Fuan Yan
Keyword(s):  
Aluminum Alloy ◽  
Grain Boundary ◽  
Corrosion Behavior ◽  
Electrochemical Measurement ◽  
Nacl Solution ◽  
Content Type ◽  
Chromate Conversion Coating ◽  
Chromate Coating ◽  
Corrosion Mechanisms ◽  
Corrosion Pits

Purpose A chromate conversion coating was prepared on the surface of bare AA2024 aluminum alloy by direct immersion in the chromating treatment bath, and the corrosion behavior of chromated AA2024 aluminum alloy in 3.5 per cent NaCl solution was studied by electrochemical measurement and microstructural observation. Design/methodology/approach According to the polarization curve test and the scanning electron microscope observation, the corrosion evolution of chromated AA2024 in 3.5 per cent NaCl solution was divided into the following three stages: coating failure, pitting corrosion and intergranular corrosion (IGC). Findings In the first stage, the chromate coating degraded gradually due to the combined action of chloride anions and water molecules, resulting in the complete exposure of AA2024 substrate to 3.5 per cent NaCl solution. Subsequently, in the second stage, chloride anions adsorbed at the sites of θ phase (Al2Cu) and S phase (Al2CuMg) on the AA2024 surface preferentially, and some corrosion pits initiated at the above two sites and propagated towards the deep of crystal grains. However, the propagation of a pit terminated when the pit front arrived at the adjacent grain boundary, where the initiation of IGC occurred. Originality/value Finally, in the third stage, the corrosion proceeded along the continuous grain boundary net and penetrated the internal of AA2024 substrate, resulting in the propagation of IGC. The related corrosion mechanisms for the bare and the chromated AA2024 were also discussed.

scholarly journals Effect of Iron Ion on Corrosion Behavior of Inconel 625 in High-Temperature Water

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Huiling Zhou ◽  
Yipeng Chen ◽  
Yi Sui ◽  
Yunfei Lv ◽  
Zhiyuan Zhu ◽  
...  
Keyword(s):  
High Temperature ◽  
Corrosion Behavior ◽  
Great Influence ◽  
Surface Oxidation ◽  
Selective Dissolution ◽  
Solid State Reactions ◽  
Inconel 625 ◽  
High Temperature Water ◽  
Corrosion Mechanisms ◽  
Temperature Water

The corrosion behavior of an ultralow iron nickel-based alloy Inconel 625 under high-temperature water has been evaluated. The results show that surface oxidation and pitting were the principal corrosion mechanisms of Inconel 625 during the initial immersion period. The surface layer of the oxide film is first Ni-enriched and then Fe-enriched as immersion time increases. The iron ions dissolved from the autoclave could lead to the formation of NiFe2O4 and have a great influence on the oxidation behavior of Inconel 625. The oxides nucleated by solid-state reactions with selective dissolution of Fe and Ni and then grew up through precipitation of cations from solution.

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