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Article
Publication date: 10 November 2020

Weiling Tuo, Shun'an Cao and Jie Zhong

The purpose of this study was to investigate the corrosion of low molecular organic acids from water-steam cycles such as acetic acid and formic acid in mental parts of…

Abstract

Purpose

The purpose of this study was to investigate the corrosion of low molecular organic acids from water-steam cycles such as acetic acid and formic acid in mental parts of steam turbine initial condensation zone.

Design/methodology/approach

The corrosion behavior of gray cast iron in initial condensate containing different concentrations of acetic acid and formic acid was studied by weight loss test, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction.

Findings

The results indicated that gray cast iron had a certain degree of corrosion in the simulated initial condensate containing acetic acid and formic acid, but the acid corrosion of gray cast iron was not only caused by low molecular organic acid but also affected by inorganic anions such as Cl. When Cl existed, after removing corrosion products, surface analysis results proved that the surface of gray cast iron was rough and uneven with many cracks, which was corrected more serious.

Originality/value

The corrosion behavior of thermal equipment by low molecular organic acids and inorganic anions in water-steam cycles was studied. The research results can provide theoretical guidelines for corrosion control of steam turbine in power plants.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 June 1973

M.N. Desai and S.S. Rana

Introduction The corrosive attack of nitric acid on copper is mainly due to the nitrous acid formed by the reaction between copper and nitric acid. The reaction is…

Abstract

Introduction The corrosive attack of nitric acid on copper is mainly due to the nitrous acid formed by the reaction between copper and nitric acid. The reaction is conditioned by: the concentration of the acid; temperature; the presence of nitrous acid; and the solubility of the reaction products in the acid. It has been suggested that as soon as a trace of NO2 has been formed by the reaction, NO3− + 2H+ + e → NO2 + H2O, it is quickly reduced to NO2− by the reaction NO2 + e → NO2−. Then NO2− combines with hydrogen ions to give nitrous acid. Nitrous acid can readily react with nitric acid to regenerate twice the original quantity of NO2 by the reaction, HNO2 + HNO3 → 2NO2 + H2O. In each cycle the quantity of NO2 and HNO2 is doubled.

Details

Anti-Corrosion Methods and Materials, vol. 20 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 August 1997

S.A. Abdel‐Hafiz, F.F. El‐Sisi, M. Helmy and A. Hebeish

Samples of loomstate cotton fabric were first treated with aqueous potassium permanganate solution at different concentrations in the presence of a non‐ionic wetting…

Abstract

Samples of loomstate cotton fabric were first treated with aqueous potassium permanganate solution at different concentrations in the presence of a non‐ionic wetting agent. The samples were then washed and treated using solutions containing methacrylic acid, wetting agent and acid or basic dye along with citric acid of different concentrations at different temperatures for different times. The critical properties of the fabric such as graft yield (expressed as carboxyl content m.eq/100g cellulose), colour strength before and after soaping and percentage loss in colour strength due to soaping were found to depend on the concentrations of KMnO4, citric acid and methacrylic acid as well as duration of the treatment. Based on the results obtained, treating formulations consisting of KMnO4 (0.1g/l), citric acid (0.1g/l), methacrylic acid (50 per cent), dye (1 per cent) and wetting agent (2g/l) was considered appropriate for concurrent grafting and dyeing of the said fabrics provided that the treatment was carried out at 90°C for 60 minutes.

Details

Pigment & Resin Technology, vol. 26 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 22 November 2011

Michael J. Mullins, David K. Luttrull and Hans Schumacher

Boric acid has been used for many years as a catalyst inhibitor and crosslinking agent to increase the glass transition temperature of epoxy resins for printed circuit…

Abstract

Purpose

Boric acid has been used for many years as a catalyst inhibitor and crosslinking agent to increase the glass transition temperature of epoxy resins for printed circuit boards (PCB), as well as in the glass fibre reinforcement. Recent regulation related to boric acid and its salts by the ECHA, a regulatory agency in the EU, may limit the use of these materials. The purpose of this paper is to describe the implications of this new regulation and to propose an analytical procedure that is relevant to PCB's.

Design/methodology/approach

Potential analytical procedures, including dissolution in acid and aqueous extraction followed by boric acid titration, are discussed and evaluated.

Findings

The use of acid for the digestion of prepreg, laminates and PCBs has the potential to greatly overstate the concentration of boric acid in PCBs.

Originality/value

An aqueous extraction method (German DIN 38414‐4) gives results that represent a worst‐case leaching process. It is proposed that it becomes the official analytical method for printed circuit boards in order to comply with the ECHA regulation.

Details

Circuit World, vol. 37 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 June 1997

Inder Singh, A.K. Bhattamishra and D.K. Basu

Stainless steels are very unique in that they offer a wide range and combination of resistance to corrosion, resistance to oxidation at high temperature and good…

Abstract

Stainless steels are very unique in that they offer a wide range and combination of resistance to corrosion, resistance to oxidation at high temperature and good mechanical properties at room temperature. With rapid industrialization all over the world, these very properties have led to extensive use of stainless steels in different industries. Austenitic stainless steels containing molybdenum exhibit corrosion resistance in both sulphuric acid and nitric acid. Stainless steel undergoes severe attack in sulphuric acid having concentrations in the range of 20‐85 per cent, whereas they are immune to nitric acid in any concentration. However, sensitized stainless steels are prone to intergranular attack in acids, even in nitric acid. Further, the attack is aggravated in the presence of aggressive ions. Study of the behaviour of stainless steels in a mixture of acids (nitric and sulphuric acid) is lacking in the literature. This paper, therefore, discusses the performance of AISI‐316 and 316‐L in sulphuric acid and nitric acid and a mixture thereof at room temperature. It is observed that the steels are quite resistant to sulphuric acid and nitric acid, but in the acid mixture they are not so resistant, especially in AISI‐316 SS in respect of corrosion resistance, even in acid mixture containing C1 and Cu++ ions.

Details

Anti-Corrosion Methods and Materials, vol. 44 no. 3
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 April 1995

J.E. Sohn and U. Ray

Weak organic acids (WOAs) are commonly used as activators in no‐clean fluxes. Surface insulation resistance (SIR) was determined as a function of WOA type and residue…

Abstract

Weak organic acids (WOAs) are commonly used as activators in no‐clean fluxes. Surface insulation resistance (SIR) was determined as a function of WOA type and residue level through three temperature/humidity test environments. Acidic residue levels were determined after wave solder processing, and after exposure to each of the three test environments. With each of the WOAs studied, the greater the residue level, the lower the SIR. Chemical structure and physical property differences of the WOAs are discussed in the context of differences in SIR observed. WOA volatilisation is found to occur with all four WOAs when exposed to the highest test temperature (85°C). This work shows that testing WOA‐containing solder fluxes at 85°C may not be useful or appropriate.

Details

Circuit World, vol. 21 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 May 1991

Edgar S. Lower

A number of derivatives of vegetable and animal oils and fats are useable in the processing of rubbers, including fatty acids, fatty acid amides, amines, metallic soaps…

Abstract

A number of derivatives of vegetable and animal oils and fats are useable in the processing of rubbers, including fatty acids, fatty acid amides, amines, metallic soaps, and sulphur containing materials, etc.

Details

Pigment & Resin Technology, vol. 20 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 August 1998

Pasi Kangas and Mark Newman

Considers the advantages of highly alloyed stainless steel such as duplex stainless steels or nickel‐based alloys in highly corrosive environments. Looks at corrosion…

Abstract

Considers the advantages of highly alloyed stainless steel such as duplex stainless steels or nickel‐based alloys in highly corrosive environments. Looks at corrosion rates for alloys in acetic acid and presents results of tests on the influence of contaminants in the acid. Gives practical applications. Concludes that duplex stainless steels demonstrate higher corrosion resistance than austenitic stainless steels and are often comparable to nickel base alloys.

Details

Anti-Corrosion Methods and Materials, vol. 45 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 June 1994

A.A. Al‐Suhybani and I.H. Al‐Hwaidi

Introduction The corrosion of iron has been extensively studied in various media. In nitric acid solutions, the corrosion of iron is much faster than in other mineral acids

Abstract

Introduction The corrosion of iron has been extensively studied in various media. In nitric acid solutions, the corrosion of iron is much faster than in other mineral acids at comparable concentrations. This is attributed to an autocatalytic process involving some nitrogen oxides, nitrous acid and/or some iron complexes. At high nitric acid concentrations, passivation of iron takes place. The factors affecting the dissolution and the passivation processes are not fully understood. The effect of various inhibitors on the corrosion of iron in acid media has been studied. Thus Ammar et al. have studied the passivation of iron and the effect of some anions, e.g. Br− and I− on the passive film. The effect of amides as inhibitors for iron in nitric acid has been reported by Fouda and Gouda. These authors have found that the corrosion process is controlled by the reaction of amides with HNO3 and not by the surface reaction. The effect of aniline and some aminobenzoic acids on the rate of corrosion of iron has been reported. The present work is aimed at examining the efficiencies of some aniline substitutes as corrosion inhibitors for the corrosion of iron in concentrated nitric acid solution.

Details

Anti-Corrosion Methods and Materials, vol. 41 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 April 2004

Lowell L. Dilworth, Felix O. Omoruyi, Oswald Simon, Errol Y. Morrison and Helen N. Asemota

In this study, phytic acid was extracted from Jamaican sweet potato, which has been reported to contain a high phytic acid to zinc ratio and fed to Wistar rats for three…

Abstract

In this study, phytic acid was extracted from Jamaican sweet potato, which has been reported to contain a high phytic acid to zinc ratio and fed to Wistar rats for three weeks. Animals were then sacrificed and blood glucose, intestinal amylase activity and faecal minerals were determined. Blood glucose levels in all the groups fed phytic acid extract from sweet potato or commercial phytic acid were reduced compared to their controls. This lowering was more pronounced in the groups fed phytic acid extract from sweet potato or commercial phytic acid plus zinc supplement. Faecal zinc was significantly higher in the groups fed phytic acid extract from sweet potato compared to the controls in weeks 1 and 2. Supplementation of the diets with phytic acid extract from sweet potato or commercial phytic acid resulted in an increase in the faecal output of iron except for the group that was fed commercial phytic acid plus zinc. Overall, the supplementation of the rat diet with phytic acid extract from sweet potato resulted in a general increase in the output of these faecal minerals.

Details

Nutrition & Food Science, vol. 34 no. 2
Type: Research Article
ISSN: 0034-6659

Keywords

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