Search results

1 – 10 of over 206000
To view the access options for this content please click here
Article
Publication date: 17 April 2020

Ankur V. Bansod, Awanikumar P. Patil and Sourabh Shukla

Low nickel austenitic stainless steel (ASS) has attracted much attention worldwide because of its economical price. This study aims to investigate the effect of different…

Abstract

Purpose

Low nickel austenitic stainless steel (ASS) has attracted much attention worldwide because of its economical price. This study aims to investigate the effect of different corrosive environments on the corrosion behavior of chrome-manganese (Cr-Mn) ASS. The tests were carried out as a function of H2SO4 concentrations, temperature and addition of ammonium thiocyanate (NH4SCN) (0.01 M). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to study the corrosion behavior of Cr-Mn ASS. It was observed that with increasing H2SO4 concentration, temperature and with the addition of NH4SCN solution, icorr, icrit and ipassive values increased. EIS data show decreasing charge transfer resistance value with increasing concentration and temperature. Higher corrosion rate with increasing temperature and concentration of H2SO4 is related to the anions (SO42−), which is responsible for reducing the stability of passive films. With the presence of 0.01 M NH4SCN thiocyanate (SCN anion), there is a higher dilution of the passive film resulting in a higher corrosion rate. Energy-dispersive spectroscopy (EDS) analysis reveals the adsorption of sulfur on the surface in NH4SCN containing a solution. The significant presence of counter ions and the adsorbed sulfur species on the steel surface play a vital role in corrosion behavior.

Design/methodology/approach

All the experiments were performed on a 3 mm thick sheet of Cr-Mn ASS (202 ASS) in hot rolled condition. The samples were then annealed at 1,050°C for 1 h, followed by water quenching. For microstructural examination, they were electrochemically etched in 10 Wt.% oxalic acid solution at 1 amp for 90 s. A computer-controlled Potentiostat (Biologic VMP-300) was used. After the cell was set up, the working electrode (WE) was electrostatically cleaned at −1 V vs saturated calomel electrode (SCE) for 30 s to remove the air-formed film. Then, WE were allowed to attain stable open circuit potential (OCP) for 1 h, following by the EIS test and potentiodynamic polarization test. The polarization test was started from a cathodic potential (−1.2 V vs SCE) and continued up to an anodic potential (1.6 V vs SCE) a scan rate of 0.1667 mV/s. EIS experiment was conducted on the same instrument by using a sinusoidal AC signal of 10 mV in a frequency range of 1,000,000 to 0.01 Hz at OCP.

Findings

Potentiodynamic polarization graph shows that with the increase in sulphuric acid concentration. Increasing temperature from 20°C to 80°C in 0.5 M H2SO4 solution increases the corrosion rate (icorr) of Cr-Mn ASS. On the addition of 0.01 M NH4SCN to the sulfuric acid solution (0.1, 0.5 and 1 M) the corrosion rate increases drastically almost four to five times. EDS and XRD analysis shows the presence of sulfur over the oxide film and preferential site for dissolution of Cr and Mn at the steel surface when NH4SCN is added to the sulfuric acid solution.

Originality/value

A study on the corrosion behavior of Cr-Mn ASS is scanty according to the author’s knowledge. Therefore, the present study will investigate the corrosion behavior of Cr-Mn ASS on SO4−2 anions, temperature and the addition of SCN ion in sulfuric acid.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here

Abstract

Details

Contingent Valuation: A Critical Assessment
Type: Book
ISBN: 978-1-84950-860-5

To view the access options for this content please click here
Article
Publication date: 1 May 1997

María J. López‐huertas

The need for thesauri to help users in their search for information in online information systems has been discussed for several decades. Many wide‐ranging contributions…

Abstract

The need for thesauri to help users in their search for information in online information systems has been discussed for several decades. Many wide‐ranging contributions have been made to solve this problem. Nevertheless, investigation is needed to design a thesaurus structure based on what is relevant for users and generators of information within a specific subject domain. This paper explores the possibility of creating a thesaurus from the cognitive viewpoint. This approach is based on a system (in this case represented by a thesaurus) that organises its representation of knowledge or its classification as closely as possible to the authors‘ and users’ images of the subject domain with the objective of increasing the interaction between users and texts, and thus the communication in a given information retrieval system. From this point of view, the thesaurus structure is considered as the essential foundation on which to base such an interactive thesaurus. Furthermore, this structure is conceived as representing the merging point for both the generators‘ and the users’ models of the subject domain and for their information needs. This paper is dedicated mainly to the generators‘ side involved in this process. It demonstrates how an author’s writings can be used to identify the generators‘ model and perception of the subject domain, and how these can later be inserted in the thesaurus structure. Discourse analysis is used as a main method to identify the categories and its relevance for building such a structure is discussed. It also outlines a general approach for the user side to set up different methods of getting the users’ information needs into the thesaurus structure.

Details

Journal of Documentation, vol. 53 no. 2
Type: Research Article
ISSN: 0022-0418

Keywords

To view the access options for this content please click here
Article
Publication date: 23 March 2012

Boris Mitavskiy, Jonathan Rowe and Chris Cannings

The purpose of this paper is to establish a version of a theorem that originated from population genetics and has been later adopted in evolutionary computation theory…

Abstract

Purpose

The purpose of this paper is to establish a version of a theorem that originated from population genetics and has been later adopted in evolutionary computation theory that will lead to novel Monte‐Carlo sampling algorithms that provably increase the AI potential.

Design/methodology/approach

In the current paper the authors set up a mathematical framework, state and prove a version of a Geiringer‐like theorem that is very well‐suited for the development of Mote‐Carlo sampling algorithms to cope with randomness and incomplete information to make decisions.

Findings

This work establishes an important theoretical link between classical population genetics, evolutionary computation theory and model free reinforcement learning methodology. Not only may the theory explain the success of the currently existing Monte‐Carlo tree sampling methodology, but it also leads to the development of novel Monte‐Carlo sampling techniques guided by rigorous mathematical foundation.

Practical implications

The theoretical foundations established in the current work provide guidance for the design of powerful Monte‐Carlo sampling algorithms in model free reinforcement learning, to tackle numerous problems in computational intelligence.

Originality/value

Establishing a Geiringer‐like theorem with non‐homologous recombination was a long‐standing open problem in evolutionary computation theory. Apart from overcoming this challenge, in a mathematically elegant fashion and establishing a rather general and powerful version of the theorem, this work leads directly to the development of novel provably powerful algorithms for decision making in the environment involving randomness, hidden or incomplete information.

To view the access options for this content please click here
Article
Publication date: 1 June 1998

Elaine Draper

Discusses US use of drug testing in the workplace, screening employees for smoking, AIDS, genetic traits and reproductive hazards. Attributes this to the costs employers…

Abstract

Discusses US use of drug testing in the workplace, screening employees for smoking, AIDS, genetic traits and reproductive hazards. Attributes this to the costs employers face in insurance, litigation and compensation. Points out that the purpose of drug testing is to circumvent management responsibility for: accidents in the workplace, stress, bad management practices, and disregarding health and safety initiatives. Acknowledges that the tests are harmful and indefensible. Reports that 81 per cent of members of the American Management Association in 1996 conducted drug testing. Claims that screening is the alternative to monitoring – that is screening out individuals who are seen as high risk in some way – yet that misses the point – the focus should be on making hazardous working conditions safe. Indicates that companies may use drug testing as a means of deterring drug users from gravitating towards their organization. Mentions that workplace‐induced stress can lead to substance abuse and that, therefore it is management driven, rather than being a problem the worker brings to the workplace. Quotes a number of company physicians who object to policing drug use. Indicates that drug testing has diverted attention away from health and safety issues and hazardous working conditions.

Details

International Journal of Sociology and Social Policy, vol. 18 no. 5/6
Type: Research Article
ISSN: 0144-333X

Keywords

To view the access options for this content please click here
Article
Publication date: 1 December 2003

F. Bensajjay, S. Alehyen, M. El Achouri and S. Kertit

1‐phenyl 5‐mercarpto 1,2,3,4‐tetrazole (PMT) was tested as an inhibitor for the corrosion of steel in 0.5 M H2SO4 and 1/3 M H3PO4 by weight‐loss and electrochemical…

Abstract

1‐phenyl 5‐mercarpto 1,2,3,4‐tetrazole (PMT) was tested as an inhibitor for the corrosion of steel in 0.5 M H2SO4 and 1/3 M H3PO4 by weight‐loss and electrochemical methods. Results obtained showed that the inhibition efficiency of PMT increased with the increase of inhibitor concentration and reached an optimum value (98 per cent) at 10−3M in H2SO4 and H3PO4 solutions. The effect of the temperature on the kinetic parameters of corrosion of steel in the aqueous solutions of H2SO4 and H3PO4 with and without addition of PMT has been studied and the associated parameters were determined.

Details

Anti-Corrosion Methods and Materials, vol. 50 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here
Article
Publication date: 1 January 1999

Kwong‐leung Tang

Examines the extent to which social policy adopted by the colonial government in Hong Kong (prior to its hand‐over China in 1997) has set the agenda for the government of…

Abstract

Examines the extent to which social policy adopted by the colonial government in Hong Kong (prior to its hand‐over China in 1997) has set the agenda for the government of the newly formed Special Administrative Region (SAR). Chronicles the historical development of social policy in Hong Kong since the inception of the colonial government in 1842; identifies that, with the exception of a short‐lived period of expansionism (stimulated by social unrest in the mid‐1960’s) social welfare provision appears to have been low on the government’s agenda and incremental in nature ‐ the emphasis being on economic growth, rather than public spending on welfare programmes. Examines the strengths and weaknesses of this incremental approach; outlines the commitment of the SAR government to the market economy and its proposals for a modest increase in welfare provision, essentially building on the legacy left behind by the colonial government.

Details

International Journal of Sociology and Social Policy, vol. 19 no. 1/2
Type: Research Article
ISSN: 0144-333X

Keywords

To view the access options for this content please click here
Article
Publication date: 14 September 2010

Yong‐Ming Tang, Yun Chen, Wen‐Zhong Yang, Xiao‐Shuang Yin, Ying Liu and Jin‐Tang Wang

The aim of this paper is to investigate inhibition of copper corrosion by 3,5‐bis(2‐thienyl)‐4‐amino‐1,2,4‐triazole (2‐TAT) in 1 M HCl and 0.5 M H2SO4.

Abstract

Purpose

The aim of this paper is to investigate inhibition of copper corrosion by 3,5‐bis(2‐thienyl)‐4‐amino‐1,2,4‐triazole (2‐TAT) in 1 M HCl and 0.5 M H2SO4.

Design/methodology/approach

Potentiodynamic polarization curves and electrochemical impedance measurements were carried out on copper in 1 M HCl and 0.5 M H2SO4 containing various concentrations of 2‐TAT, and the effects of temperature were also investigated.

Findings

As an efficient inhibitor, 2‐TAT behaves better in 1 M HCl than in 0.5 M H2SO4. 2‐TAT can be classified as cathodic‐type corrosion inhibitor in 1 M HCl and acts as relatively mixed type in 0.5 M H2SO4. Activation energies in the presence and absence of 2‐TAT were obtained by measuring the temperature independence of corrosion current. Adsorption of the inhibitor on the copper surface was found to obey the Langmuir adsorption isotherm.

Practical implications

This inhibitor could have application in industries where hydrochloric acid solutions are used to remove scale and salts from copper surfaces and may render dismantling unnecessary.

Originality/value

The results from this paper showed that 2‐TAT could be considered as a suitable inhibitor for copper in acidic media.

Details

Anti-Corrosion Methods and Materials, vol. 57 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here
Article
Publication date: 4 July 2016

Moses M. Solomon, Saviour A. Umoren, Aniekemeabasi U. Israel and Idongesit G. Etim

The purpose of this paper is to evaluate the performance of polypropylene glycol (PPG), as a corrosion inhibitor for aluminium corrosion in 0.5 M H2SO4 solution at 303-333…

Abstract

Purpose

The purpose of this paper is to evaluate the performance of polypropylene glycol (PPG), as a corrosion inhibitor for aluminium corrosion in 0.5 M H2SO4 solution at 303-333 K and the effect of addition of iodide ions on the corrosion inhibition efficacy of PPG.

Design/methodology/approach

The corrosion inhibition performance of PPG alone and on addition of iodide ions in the acid medium was evaluated using weight loss and electrochemical [electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and potentiodynamic polarization (PDP)] methods as well as surface analysis approach at 303-333 K. The morphology of the corroding aluminium surface without and with the additives was visualised using scanning electron microscopy (SEM). The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption.

Findings

Results obtained showed that PPG moderately retarded the corrosion of Al in 0.5 M H2SO4 solution. Addition of KI to PPG is found to synergistically improve the inhibitive ability of PPG. From the variation of inhibition efficiency, K_ads, and E_a, with rise in temperature, physisorption mechanism is proposed for the adsorption of PPG and PPG + KI onto the Al surface in 0.5 M H2SO4 solution. Polarisation results showed that PPG and PPG + KI acted as mixed type inhibitor. The adsorption of PPG and PPG + KI, respectively, onto the metal surface followed El-Awady et al. adsorption isotherm model. SEM and water contact angle analysis confirmed the adsorption of PPG and PPG + KI on Al surface.

Research limitations/implications

The research is limited to aqueous acid environment in aerated condition, and all tests were performed under static conditions.

Practical implications

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

Originality/value

The use of PPG as corrosion inhibitor for Al corrosion in acidic medium were reported for the first time. The results suggest that iodide ions could be used to enhance corrosion protection ability of PPG which could find practical application in corrosion control in aqueous acidic environment. The data obtained would form part of database on the synergistic effect of iodide ions addition to polymer to control acid-induced corrosion of metal.

Details

Pigment & Resin Technology, vol. 45 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

To view the access options for this content please click here
Article
Publication date: 1 June 1998

William R. Freudenburg, Scott Frickel and Rachel E. Dwyer

Examines the debate over “Higher superstition” (Gross and Levitt, 1994). Puts forward the arguments in the book and the response to the book from members of the US science…

Abstract

Examines the debate over “Higher superstition” (Gross and Levitt, 1994). Puts forward the arguments in the book and the response to the book from members of the US science and technology studies community. Asserts that increases in technical control have been at the expense of social and individual control. Mentions “diversionary reframing” – changing the subject, possibly by diverting attention away from the subject matter to the person doing the criticizing. Explores public attitudes towards science and technology, quoting a number of layman approaches to the bafflement of science. Identifies the irony in Gross and Levitt’s arguments, particularly in developing the interface between science and technology. Recommends paying more attention to the social construction of beliefs.

Details

International Journal of Sociology and Social Policy, vol. 18 no. 5/6
Type: Research Article
ISSN: 0144-333X

Keywords

1 – 10 of over 206000