Search results

1 – 10 of 11
Click here to view access options
Article
Publication date: 6 November 2017

Jiayuan Hu, Zhixing Fang, Zhouhai Qian, Xiaoming Shen, Haifei Zhou and Dongchun Jin

The purpose of this paper is to study the cause of severe corrosion of the galvanized lightning rods in a 220 kV transformer substation, and to seek the effective…

Abstract

Purpose

The purpose of this paper is to study the cause of severe corrosion of the galvanized lightning rods in a 220 kV transformer substation, and to seek the effective corrosion inhibition measures for the hollow lightning rods.

Design/methodology/approach

The corrosion morphology and rust component of lightning rod was analyzed, and the corrosion process of lightning rod was researched by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), ion chromatography and electrochemical tests.

Findings

The results indicated that the outer surface of hollow lightning rod was corroded slightly; however, its inner surface suffered severe corrosion because of a long time high-humidity environment inside the tube caused by the rainwater permeation. A rust layer consisted of Fe3O4 and a little FeOOH was accumulated on the inner surface of the hollow lightning rod. Moreover, Fe3O4 rust layer worked as a large cathode area which could promote the corrosion of metal substrate further. A self-accelerating corrosion process was formed on the inner surface, making the corrosion failure of lightning rod occurred and aggravated gradually.

Originality/value

The corrosion of inner surface of hollow lightning rod cannot be detected easily. More attention should be paid to the corrosion inhibition of lightning rod. The key of corrosion inhibition for the hollow lightning rod was to avoid the rainwater accumulation inside tube. The research results can provide guidelines on the corrosion inhibition measures selection of lightning rod in transformer substation.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 5 June 2017

Jianli Xie, Jiayuan Hu, Jundong Lu and Xinmin Li

The purpose of this paper was to study the corrosion control of B10 copper-nickel alloy using the LiOH-N2H4 compound inhibitors and to evaluate the feasibility of…

Abstract

Purpose

The purpose of this paper was to study the corrosion control of B10 copper-nickel alloy using the LiOH-N2H4 compound inhibitors and to evaluate the feasibility of replacing the original inhibitors (NaNO2-Na2MoO4) with the new ones (LiOH-N2H4) for the chilled water system in a nuclear unit.

Design/methodology/approach

The corrosion resistance performance of B10 copper-nickel alloy was evaluated during the whole replacement process of inhibiters using electrochemical tests and surface analysis techniques.

Findings

The results indicated that the corrosion of B10 copper-nickel alloy could be prevented effectively using LiOH to increase the pH value of solution higher than 10.0 and using N2H4 to consume dissolved oxygen. During the replacement process of inhibitors from NaNO2-Na2MoO4 to LiOH-N2H4, the corrosion resistance performance of B10 copper-nickel alloy had not decreased greatly. The new LiOH-N2H4 inhibitor, which could enhance the compactness of rust, was able to reduce the corrosion rate of rusted B10 metal.

Originality/value

It is feasible and operable to replace the NaNO2-Na2MoO4 inhibitors with the LiOH-N2H4 inhibitors for the corrosion prevention of B10 copper-nickel alloy. The research results can provide guidelines for the inhibitor selection of chilled water system in a nuclear unit.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 25 February 2014

Jiayuan Hu, Shun'an Cao, Jianli Xie and Li Yin

The purpose of this investigation was to study the effects of sodium hexametaphosphate and zinc sulfate on the corrosion control of rusted iron in reverse osmosis (RO…

Abstract

Purpose

The purpose of this investigation was to study the effects of sodium hexametaphosphate and zinc sulfate on the corrosion control of rusted iron in reverse osmosis (RO) product water of seawater.

Design/methodology/approach

The synergistic effects and inhibition effects of corrosion inhibitors on rusted carbon steel were studied using the weight-loss method, electrochemical tests and surface analysis techniques.

Findings

The results indicated that sodium hexametaphosphate could partly suppress the corrosion of rusted steel, but zinc sulfate used alone had no inhibition effect. Hexametaphosphate and zinc sulfate showed a strong synergistic effect and the optimal ratio of two chemicals was 1:1. The inhibition efficiency appeared to increase with increasing inhibitor concentration and the ideal dosage of inhibitors was set at 20 mg/L, when chemical cost and inhibition efficiency were taken into account. Surface analysis results proved that this compound inhibitor could make the rust layer much more compact. The inhibitive mechanism was to combine with rust and form a protective film, which consisted of iron oxide, polyphosphate and Zn(OH)2.

Originality/value

It was found that the compound inhibitor consisting of sodium hexametaphosphate and zinc sulfate had a good inhibitive effect on rusted iron in RO product water. The research results can provide theoretical guidelines for corrosion control of rusted pipes in power plants.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 29 April 2014

Jiayuan Hu, Shun-an Cao, Li Yin and Yang Gao

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on…

Abstract

Purpose

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on metal corrosion and establishing a corrosion model for rusted iron.

Design/methodology/approach

The corrosion behavior of rusted carbon steel in dilute NaCl solution was studied by means of weight-loss determinations, scanning electron microscopy, Raman spectrometry and electrochemical techniques.

Findings

The results indicated that carbon steel had a similar corrosion behavior in all three NaCl solutions. The iron rust, which consisted of a thin γ-FeOOH layer and a thick Fe3O4 layer, can facilitate the corrosion process of carbon steel via reduction of γ-FeOOH and the large area cathode of Fe3O4. Hence, the corrosion rate of carbon steel was accelerated significantly and finally was determined by the limiting diffusion rate of oxygen.

Originality/value

A corrosion model of rusted carbon steel was established, suggesting that iron rust formed in all slightly acidic waters with low alkalinity probably promotes the corrosion of carbon steel. Anti-corrosion measures for iron in this type of solution, such as desalination water, should be aimed to reduce the promotional effect of the rust layer on metal corrosion.

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 15 March 2013

Jiayuan Hu, Shun‐an Cao and Jianli Xie

The purpose of this paper is to explore the long‐term corrosion behavior of carbon steel in 3% NaCl solution and evaluate the effect of rust layer on the corrosion process.

Abstract

Purpose

The purpose of this paper is to explore the long‐term corrosion behavior of carbon steel in 3% NaCl solution and evaluate the effect of rust layer on the corrosion process.

Design/methodology/approach

The corrosion behavior of rusted carbon steel in 3% NaCl solution was studied by means of infrared spectroscopy (IR) and electrochemical impedance spectroscopy (EIS).

Findings

The results indicated that the corrosion of carbon steel was affected by chloride ion in initial immersion and then controlled by the rust layer. The rust layer consisted of a thin outer layer (γ‐FeOOH layer) and a thick inner layer (Fe3O4 layer). The outer rust layer facilitated the cathodic process via reduction of γ‐FeOOH, while the inner rust layer provided a large cathode area and oxygen could be reduced on its surface. As a result, the corrosion rate of carbon steel was determined by the limiting diffusion rate of oxygen and stabilized at a high value.

Originality/value

The corrosion model of rusted carbon steel in 3% NaCl solution was established. It is probable that the iron rust in all slightly acidic water with low alkalinity can promote the corrosion process via reduction of γ‐FeOOH. Anti‐corrosion measures for iron in this type of solutions should be aimed to reduce the promoting effect of rust layer on the metal corrosion. The NaCl solution prepared from tap water is more suitable for the substitution of artificial water than that prepared from deionized water.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 2 November 2012

Jiayuan Hu, Shunan Cao, Li Yin, Qinqin Liang and Jianli Xie

Some power plants in China that adopt reverse osmosis (RO) product water as their fresh water source face serious metal corrosion of their water distribution system. The…

Abstract

Purpose

Some power plants in China that adopt reverse osmosis (RO) product water as their fresh water source face serious metal corrosion of their water distribution system. The corrosion process of carbon steel in RO product water is still not clear and there is no suitable anti‐corrosion method for the power plant to employ. The purpose of this paper is to study the corrosion behavior of carbon steel in RO product water, determine the factors leading to the high corrosion rate of carbon steel, and then suggest appropriate anti‐corrosion measures.

Design/methodology/approach

By measuring polarization curves and AC impedance values of the corrosion system and analyzing corrosion products using scanning electron microscopy (SEM), infrared spectroscopy (IR) and X‐ray diffraction (XRD), the corrosion behavior of Q235A carbon steel in the RO product water derived from seawater was studied.

Findings

The experimental results showed that the corrosion process of carbon steel in RO product water is controlled by the diffusion process of oxygen, and the corrosion products contain γ‐FeOOH, Fe3O4 and small amounts of α‐FeOOH. Although rust formed had a double layer structure, the outer rust layer, which contained γ‐FeOOH and a little α‐FeOOH, was thin. The inner rust layer, containing Fe3O4, was the main component of the rust layer. Due to the weak acidity of RO product water, γ‐FeOOH can be transformed to Fe3O4 very quickly and Fe3O4 will accumulate on the metal surface. Because of the electrical conductivity and fractured surface of the Fe3O4 layer, the corrosion product layer cannot inhibit the corrosion process by hindering the diffusion process of oxygen, and hence the corrosion rate of carbon steel is always high.

Originality/value

The paper describes the first systematic research to be carried out on the corrosion behavior of carbon steel in RO product water. It was found that the generation and accumulation of Fe3O4 on the metal surface was the primary reason leading to the high corrosion rate of carbon steel, and anti‐corrosion measures can be chosen following the following rules: deoxygenation, raising of the pH of the solution, or addition of corrosion inhibitors to the solution.

Details

Anti-Corrosion Methods and Materials, vol. 59 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 4 January 2013

Shun'an Cao, Jiayuan Hu, Jianli Xie, Qinqin Liang and Li Yin

The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at…

Abstract

Purpose

The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at high temperatures, and determine the optimum process condition of shutdown protection for units under full load if ODA has a good film‐forming effect at high temperatures.

Design/methodology/approach

An autoclave was used to simulate the water‐vapor environments at 350‐560°C in the water‐steam system of power plants. The decomposition test of ODA was investigated and the ODA film‐forming characteristics were studied for furnace tube materials used in gas‐fired power plants.

Findings

Results showed that ODA had a decomposition equilibrium and the decomposition products did not contain harmful organic substances such as low molecular organic acids. ODA would form a satisfactory protective film in the range of 350‐560°C with the best film at 480°C. The protection effect of the film formed by ODA at 560°C was much stronger than was that of its oxide film, which showed the feasibility of shutdown protection using ODA for gas‐fired power plants operating under full load. The optimal conditions of shutdown protection under full load were as follows: the temperature was 560°C, the concentration of ODA was 80 mg/L, the pH was 9.5 and the exposure time was 2 h. From the experimental results of X‐ray photoelectron spectroscopy, it was known that the surface film on the specimens was composed of a compound of ferroferric oxide and ODA, and the film‐forming mechanism was chemical adsorption between N in the ODA and Fe.

Originality/value

It was found that ODA has a good film‐forming effect at high temperatures and it is practicable to implement shutdown protection for base‐load units. The research results can provide theoretical guidelines for shutdown protection of gas‐fired power plants.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Abstract

Details

Anti-Corrosion Methods and Materials, vol. 61 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Click here to view access options
Article
Publication date: 28 September 2021

Muhammad Hasan Ashraf, Mehmet G. Yalcin, Jiayuan Zhang and Koray Ozpolat

Third-party logistics (3PL) companies have experienced an explosion of volume during coronavirus disease 2019 (COVID-19). Special tiers have been introduced to provide…

Abstract

Purpose

Third-party logistics (3PL) companies have experienced an explosion of volume during coronavirus disease 2019 (COVID-19). Special tiers have been introduced to provide differentiated levels of service to the customers. However, such changes in an organization reveal and intensify tensions known as paradoxes. The purpose of this research is to identify what paradoxes emerged or have become more salient specifically due to COVID-19 in 3PLs' ground operations and how they are dealt with by ground operation managers.

Design/methodology/approach

This is a qualitative study conducted in two phases. Phase one utilizes a questionnaire approach to identify the paradoxes within the 3PLs operating in the USA. Phase two, conducted six months after phase one, follows an in-depth one-on-one interview approach. NVivo 12 is employed to analyze the interview data.

Findings

The results show that new paradoxes did in fact emerge due to the COVID-19 and are mostly related to the performing paradox category. Findings from in-depth interviews show that the 3PL managers focus on keeping safety as priority to manage COVID-19 related paradoxes, along with modifying operational plans, improving communication, investing in training, optimizing hub network, introducing modified/new methods and adapting modified human resource policies.

Originality/value

This paper is among the first known to identify paradoxes within the 3PL operations during the COVID-19 and provides insights into how these paradoxes are dealt with at mid-management level. Findings of this study provide foundations for the development of a theoretical framework on handling paradoxes within 3PLs.

Details

The International Journal of Logistics Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0957-4093

Keywords

Click here to view access options
Article
Publication date: 4 March 2014

Shaobo Ni and Jiayuan Shan

The purpose of this paper is to present a sliding mode attitude controller for reusable launch vehicle (RLV) which is nonlinear, coupling, and includes uncertain…

Abstract

Purpose

The purpose of this paper is to present a sliding mode attitude controller for reusable launch vehicle (RLV) which is nonlinear, coupling, and includes uncertain parameters and external disturbances.

Design/methodology/approach

A smooth second-order nonsingular terminal sliding mode (NTSM) controller is proposed for RLV in reentry phase. First, a NTSM manifold is proposed for finite-time convergence. Then a smooth second sliding mode controller is designed to establish the sliding mode. An observer is utilized to estimate the lumped disturbance and the estimation result is used for feedforward compensation in the controller.

Findings

It is mathematically proved that the proposed sliding mode technique makes the attitude tracking errors converge to zero in finite time and the convergence time is estimated. Simulations are made for RLV through the assumption that aerodynamic parameters and atmospheric density are perturbed. Simulation results demonstrate that the proposed control strategy is effective, leading to promising performance and robustness.

Originality/value

By the proposed controller, the second-order sliding mode is established. The attitude tracking error converges to zero in a finite time. Meanwhile, the chattering is alleviated and a smooth control input is obtained.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 7 no. 1
Type: Research Article
ISSN: 1756-378X

Keywords

1 – 10 of 11