scholarly journals Selective Etching of Sr-Modified and Directionally Solidified Industrial Al–Si Eutectic Alloys for Fabricating Fibrous Eutectic Si

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1974
Author(s):  
Jianjun Gao ◽  
Wei Gu ◽  
Fenfei Zhang ◽  
Haibin Geng ◽  
Jianhua Zhong ◽  
...  
Keyword(s):  
Pitting Corrosion ◽  
Selective Etching ◽  
Eutectic Alloys ◽  
Directionally Solidified ◽  
Optimal Amount ◽  
Eutectic Si ◽  
Constant Potential ◽  
Pit Depth ◽  
Voltammetry Methods ◽  
Hcl Solution

In order to fabricate fibrous eutectic Si, the selective etching of industrial Al–Si eutectic alloys directionally solidified at different growth rates and modified by different amounts of Sr was studied. Flake eutectic and fibrous Si were obtained by selective etching of non-modified, Sr-modified or directionally solidified Al–Si eutectic alloys. The optimal amount of Sr for fabricating branching eutectic Si was 0.04–0.07%. Through directional solidification with a high enough growth rate (more than 200 μm/s), lamellar eutectic Si transforms to fibrous eutectic Si for use in non-modified Al–Si eutectic alloys. The potentiodynamic polarization and cyclic voltammetry methods were used to test the corrosion behavior of non-modified and Sr-modified Al–Si eutectic alloys. With a constant potential of 0.5 V in HCl solution, non-modified Al–Si eutectic alloys displayed initial pitting corrosion and subsequent spalling corrosion, and 0.04% Sr-modified samples displayed uniform pitting corrosion. Compared with non-modified Al–Si eutectic alloys, Sr-modified samples displayed better corrosion resistance with lower current density and shallower pit depth during the same etching conditions.

scholarly journals Pitting Corrosion of Natural Aged Al–Mg–Si Extrusion Profile

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1081 ◽  
Author(s):  
Quanmei Guan ◽  
Jing Sun ◽  
William Wang ◽  
Junfeng Gao ◽  
Chengxiong Zou ◽  
...  
Keyword(s):  
Pitting Corrosion ◽  
High Speed ◽  
Three Dimensional ◽  
Optical Microscope ◽  
Damage Initiation ◽  
Coarse Grains ◽  
Corrosion Risk ◽  
Heterogeneous Microstructures ◽  
Set Up ◽  
Pit Depth

With the quick development of the high-speed railway and the service of the China Railway High-speed (CRH) series for almost a decade, one of the greatest challenges is the management/maintenance of these trains in environmental conditions. It is critical to estimate pitting damage initiation and accumulation and set up a corresponding database in order to support the foundations for interactive corrosion risk management. In this work, the pitting corrosion of a nature-aged commercial 6005A-T6 aluminum extrusion profile for 200 days was studied comprehensively. The heterogeneous microstructures were conventionally identified by the in situ eddy current, suggesting which investigated regions to fabricate samples for. After constant immersion for 240 h in 3.5 wt % NaCl, the shapes and depths of the pits were captured and measured by optical microscope (OM) and three-dimensional optical profilometry (OP), providing detailed quantification of uniform pitting corrosion. The typical features of the pits dominated by the distribution of precipitates include the peripheral dissolution of the Al matrix, channeling corrosion, intergranular attack, and large pits in the grains. Due to the high density of continuous anodic and cathodic particles constituted by alloying elements in coarse grains, the number of pits in the coarse grains was the highest while the number in the fine grains was the lowest, indicating that fine grains have the best corrosion resistance. The experimental dataset of the pit depth integrated with its corresponding microstructure would set the benchmark for further modeling of the pit depth and the remaining ductility, in order to manage the damage tolerance of the materials.

A Monte Carlo Model for Pitting Corrosion in Phosphor Bronze Tape Used in Underground Power Transmission Cables

CORROSION ◽  
10.5006/3347 ◽  
2020 ◽  
Vol 76 (1) ◽  
pp. 82-92
Author(s):  
Lixin Zhang ◽  
Simon Gill ◽  
Sivashangari Gnanasambandam ◽  
Maurizio Foresta ◽  
Jingzhe Pan ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Pitting Corrosion ◽  
Depth Distribution ◽  
Power Transmission ◽  
Monte Carlo Model ◽  
Probability Of Failure ◽  
Distribution Model ◽  
Pit Depth ◽  
Random Nature

Life of underground oil-filled power transmission cables used with phosphor bronze tapes is greatly reduced by pitting corrosion and hence accurate prediction of the pit growth in these tapes becomes essential. In the present work, the probability distribution of corrosion pit depth on phosphor bronze tapes is calculated using probabilistic Monte Carlo simulations and compared with the measured pit depth distribution on samples of broken tapes which have been in service for about 50 y. This Monte Carlo simulation is performed on every stable pit that nucleates, propagates, and repassivates on the metal surface. Due to the random nature of pitting corrosion, the probability of failure of this class of cables can be simulated based on the Monte Carlo model. This paper shows that the simulated pit depth distribution is very similar to the experimental data. The results demonstrate that the Monte Carlo model by Engelhardt and Macdonald can be effectively applied to long-term field data of phosphor bronze tapes, even over 50 y. In addition, the probability of failure due to pitting corrosion can be evaluated analytically, without need of conducting expensive and time-consuming experimental campaigns. Therefore, this probabilistic pit depth distribution model will be a powerful tool in the decision-making strategy for the replacement of underground power transmission cables near their end of life.

Morphological Characteristics of W-Nanowires after Selective Etching

2014 ◽  
Vol 1004-1005 ◽  
pp. 24-27
Author(s):  
Wen Jia Wang ◽  
Zhi Long Zhao ◽  
Ming Tang ◽  
Jian Jun Gao
Keyword(s):  
Growth Rate ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Morphological Characteristics ◽  
Selective Dissolution ◽  
Stability Diagram ◽  
Selective Etching ◽  
Directionally Solidified ◽  
Solidification Furnace ◽  
Nial Matrix

An eutectic NiAl–1.5 at.% W alloy prepared by using directionally solidified (DS)was employed as a source for producing W-nanowires. Several growth rate of 8,15,25/s was respectively used at a temperature gradient of ~240 K/cm in a Bridgman-type directional solidification furnace. A combined stability diagram was applied to predict proper conditions for the selective dissolution of NiAl matrix to get W-wires. Etching in a mixture of HCl:H2O2released parallel aligned W-nanowires with a wire diameter of ~500 nm. Different morphologies, such as nanobelts, lotus-shaped, conical of W-nanowires are obtained at the different conditions.

Analysis of the Pitting Corrosion’s Effect on the Residual Strength of Submerged Pressure Shell

2019 ◽  
Author(s):  
Weijun Xu ◽  
Tianyi Chen ◽  
Chenfeng Li ◽  
Xueqian Zhou ◽  
Feng Liu
Keyword(s):  
Finite Element ◽  
Pitting Corrosion ◽  
Residual Strength ◽  
Complex Structure ◽  
Element Model ◽  
Element Analysis ◽  
Influence Coefficients ◽  
The Finite Element Analysis ◽  
Corrosion Pit ◽  
Pit Depth

Abstract Submerged pressure shell’s corrosion situation is more serious due to bad work environment, complex structure and difficulty of maintenance. Based on the analysis of calculation method of submerged pressure shell structures with non-corrosion, the calculation formula of pressure shell with pitting corrosion is given. The Finite Element Model is constructed and its residual strength is investigated. The relationships between shell stress and some parameters, such as radius of corrosion pit, depth of corrosion pit and location of corrosion pit are studied. Based on the finite element analysis results, the effect of radius of corrosion pit on the stress of pressure shell with pitting corrosion is analyzed. Furthermore, the influence coefficients of residual strength of pressure shell due to depth and location of pitting corrosion are determined, which provide a reference for the strength evaluation of submerged pressure shell with pitting corrosion.

Effect of Pitting Corrosion on Strength of AISI 410 Stainless Steel Compressor Blades

2014 ◽  
Vol 606 ◽  
pp. 227-231 ◽  
Author(s):  
Mazmir Mat Noh ◽  
Farzin Mozafari ◽  
Muhammad Adil Khattak ◽  
Mohd Nasir Tamin
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Tensile Specimen ◽  
Maximum Diameter ◽  
Compressor Blades ◽  
Strength Tests ◽  
Corrosion Pits ◽  
Pit Depth ◽  
Geometry Analysis ◽  
Nucleation Phenomenon

In the present paper, effects of pitting corrosion on the strength of members made of AISI 410 Martensitic stainless steel were investigated. Stainless steel compressor blades in power generation industries commonly suffer from pitting corrosion. Pits geometry analysis and strength tests have been conducted. Pits geometry analysis established the maximum pit depth of 0.26 mm along with the maximum diameter of 1 mm. In addition, strength and elongation of the pitted tensile specimen gradually decrease with the increase of the area lost due to pitting corrosion. A damage nucleation phenomenon at the initial load values is also postulated.

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