Pub Date : 2002-02-01DOI: 10.1179/000705902225002358
S. Prakash, S. Singh
Abstract Molten vanadate induced hot corrosion is a serious problem in power plants using residual fuel oil. In this investigation the effects of MgO and CaO on the hot corrosion behaviour of an iron based superalloy, Superfer 800H (equivalent to Incoloy 800) has been investigated using an aggressive environment of Na2SO4-60 wt-%V2O at 900°C for up to 50 cycles. Weight change has been plotted with respect to time to establish the corrosion kinetics. Corrosion products were analysed by SEM, X-ray diffraction, and electron probe microanalysis (EPMA). X-ray diffraction identified the presence of the phases FeV2O4, Fe2O3, FeS, NiO, and Cr2O3, together with Mg3V2O8 in the case of MgO coated specimens and Ca3V2O8 in the case of CaO coated specimens. These latter phases remain solid at 900°C, explaining the inhibiting behaviour of CaO and MgO. The presence of various oxides and spinels was identified by EPMA. It is concluded that MgO and CaO injected onto hot section surfaces can be used to counteract hot corrosion of Superfer 800H owing to trace impurities of Na, V, and S in residual fuel oil.
{"title":"Effects of MgO and CaO on hot corrosion of Fe base superalloy Superfer 800H in Na2SO4-60%V205 environment","authors":"S. Prakash, S. Singh","doi":"10.1179/000705902225002358","DOIUrl":"https://doi.org/10.1179/000705902225002358","url":null,"abstract":"Abstract Molten vanadate induced hot corrosion is a serious problem in power plants using residual fuel oil. In this investigation the effects of MgO and CaO on the hot corrosion behaviour of an iron based superalloy, Superfer 800H (equivalent to Incoloy 800) has been investigated using an aggressive environment of Na2SO4-60 wt-%V2O at 900°C for up to 50 cycles. Weight change has been plotted with respect to time to establish the corrosion kinetics. Corrosion products were analysed by SEM, X-ray diffraction, and electron probe microanalysis (EPMA). X-ray diffraction identified the presence of the phases FeV2O4, Fe2O3, FeS, NiO, and Cr2O3, together with Mg3V2O8 in the case of MgO coated specimens and Ca3V2O8 in the case of CaO coated specimens. These latter phases remain solid at 900°C, explaining the inhibiting behaviour of CaO and MgO. The presence of various oxides and spinels was identified by EPMA. It is concluded that MgO and CaO injected onto hot section surfaces can be used to counteract hot corrosion of Superfer 800H owing to trace impurities of Na, V, and S in residual fuel oil.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"42 1","pages":"56 - 62"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77449235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002367
G. Kılınççeker, B. Yazıcı, A. Yilmaz, M. Erbil
Abstract The effect of phosphate ions on the corrosion behaviour of copper in sulphate solutions was investigated at different temperatures (293, 313, 333, and 353 K) and at different pH values (pH = 2·1, 7·2, and 12·3). A three electrode electrochemical technique was used for the measurements, using a saturated calomel electrode (SCE) for reference purposes. Both anodic and cathodic polarisation curves were established, from which the anodic and cathodic Tafel constants were determined. Corrosion potentials were determined by extra trapolation of the anodic and cathodic Tafel lines to the point of zero current density. The results showed that for a pH value of 2·1, the corrosion rate of copper showed a marked tendency to increase with increasing temperature in solutions containing either sulphate alone or sulphate plus phosphate. However, at pH values of 7·2 and 12·3, this tendency became less pronounced in solutions containing sulphate alone and in solutions containing sulphate plus phosphate together, max imum corrosion rates were greatly reduced and showed less tendency to increase with increasing temperature. Anodic and cathodic reaction mechanisms are proposed to explain the observations for the corrosion of copper.
{"title":"Effect of phosphate ions on electrochemical behaviour of copper in sulphate solutions","authors":"G. Kılınççeker, B. Yazıcı, A. Yilmaz, M. Erbil","doi":"10.1179/000705902225002367","DOIUrl":"https://doi.org/10.1179/000705902225002367","url":null,"abstract":"Abstract The effect of phosphate ions on the corrosion behaviour of copper in sulphate solutions was investigated at different temperatures (293, 313, 333, and 353 K) and at different pH values (pH = 2·1, 7·2, and 12·3). A three electrode electrochemical technique was used for the measurements, using a saturated calomel electrode (SCE) for reference purposes. Both anodic and cathodic polarisation curves were established, from which the anodic and cathodic Tafel constants were determined. Corrosion potentials were determined by extra trapolation of the anodic and cathodic Tafel lines to the point of zero current density. The results showed that for a pH value of 2·1, the corrosion rate of copper showed a marked tendency to increase with increasing temperature in solutions containing either sulphate alone or sulphate plus phosphate. However, at pH values of 7·2 and 12·3, this tendency became less pronounced in solutions containing sulphate alone and in solutions containing sulphate plus phosphate together, max imum corrosion rates were greatly reduced and showed less tendency to increase with increasing temperature. Anodic and cathodic reaction mechanisms are proposed to explain the observations for the corrosion of copper.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"18 1","pages":"23 - 30"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81605903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1109/MCOMSTD.2017.8258593
G. Masini, C. Gunther, Jonathan Segev, Y. Zhang, Huan Deng, G. Lee, Dong Wang, E. Kowalczyk, Kangchan Lee, Leo Lehmann, Tom Huber, S. Gorshe, S. Shew, Stefano Ruffini, S. Rodrigues, H. Youm, Yutaka Miyake, A. Taddei
{"title":"Standards news","authors":"G. Masini, C. Gunther, Jonathan Segev, Y. Zhang, Huan Deng, G. Lee, Dong Wang, E. Kowalczyk, Kangchan Lee, Leo Lehmann, Tom Huber, S. Gorshe, S. Shew, Stefano Ruffini, S. Rodrigues, H. Youm, Yutaka Miyake, A. Taddei","doi":"10.1109/MCOMSTD.2017.8258593","DOIUrl":"https://doi.org/10.1109/MCOMSTD.2017.8258593","url":null,"abstract":"","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"1 1","pages":"7 - 7"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82280414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002439
X. Zhao, N. Cui, J. Luo, S. Chiovelli
Abstract The effects of erosion on the corrosion of two types of stainless steel in aqueous 0·5M NaCl and 1M NaCl environments at ambient temperature have been studied using a modified rotating cylinder electrode system. Erosion by silica particles greatly increased the passive current density for both ferritic type 430 and austenitic type 316 stainless steels. It is suggested that two factors were largely responsible for the observed effects. The impact of the eroding silica particles on the specimen surface destroyed the passive film and removed corrosion products from the specimen surface; and impact with the fast moving silica particles generated numerous microplastic deformation sites on the metal surface which were activated owing to the presence of residual stress, dislocations and defects, etc., and the emission of low energy electrons.
{"title":"Effects of erosion on corrosion of type 430 and 316 stainless steels in aqueous environments","authors":"X. Zhao, N. Cui, J. Luo, S. Chiovelli","doi":"10.1179/000705902225002439","DOIUrl":"https://doi.org/10.1179/000705902225002439","url":null,"abstract":"Abstract The effects of erosion on the corrosion of two types of stainless steel in aqueous 0·5M NaCl and 1M NaCl environments at ambient temperature have been studied using a modified rotating cylinder electrode system. Erosion by silica particles greatly increased the passive current density for both ferritic type 430 and austenitic type 316 stainless steels. It is suggested that two factors were largely responsible for the observed effects. The impact of the eroding silica particles on the specimen surface destroyed the passive film and removed corrosion products from the specimen surface; and impact with the fast moving silica particles generated numerous microplastic deformation sites on the metal surface which were activated owing to the presence of residual stress, dislocations and defects, etc., and the emission of low energy electrons.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"PP 1","pages":"63 - 68"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84296923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002420
Á. Pardo, E. Otero, M. Merino, M. D. López, M. Vázquez, P. Agudo, M. D. Escalera, A. Mhich
Abstract This study addressed the influence of Cr concentration on the corrosion resistance of Co73·5Si13 ·5B9Nb3Cu1 metallic glass in simulated marine atmospheres with 1000 ppm of chlorides. Anodic and cyclic polarisation measurements were carried out to study the susceptibility to passivation and localised corrosion. The corrosion kinetics were analysed using dc electrochemical techniques. Every test was conducted using the same material in different states: amorphous, nanocrystalline and crystalline. The study also focused on changes in the magnetic properties of the material as a result of Cr addition and exposure to an aggressive medium. These properties depend mainly on the Cr concentration and the material state (amorphous, crystalline or nanocrystalline).
{"title":"Influence of chromium additions on corrosion resistance of Co75·5Si13·5B9 Nb3Cu1 metallic glass in marine environment","authors":"Á. Pardo, E. Otero, M. Merino, M. D. López, M. Vázquez, P. Agudo, M. D. Escalera, A. Mhich","doi":"10.1179/000705902225002420","DOIUrl":"https://doi.org/10.1179/000705902225002420","url":null,"abstract":"Abstract This study addressed the influence of Cr concentration on the corrosion resistance of Co73·5Si13 ·5B9Nb3Cu1 metallic glass in simulated marine atmospheres with 1000 ppm of chlorides. Anodic and cyclic polarisation measurements were carried out to study the susceptibility to passivation and localised corrosion. The corrosion kinetics were analysed using dc electrochemical techniques. Every test was conducted using the same material in different states: amorphous, nanocrystalline and crystalline. The study also focused on changes in the magnetic properties of the material as a result of Cr addition and exposure to an aggressive medium. These properties depend mainly on the Cr concentration and the material state (amorphous, crystalline or nanocrystalline).","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"1 1","pages":"69 - 75"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89642775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002402
T. Du
Abstract The semiconductor properties, electronic structure and reduction susceptibility of passive films on AISI type 304 stainless steel in dilute sulphuric acid solutions have been studied by electrochemical impedance spectroscopy measurements, Mott-Schottky analysis and the photoelectrochemical technique. The passive film shows features of an amorphous or highly disordered n type semiconductor. The donor level is in the range of 1026-1027 m-3 and increases with the amplitude of ac potential. The passive film thickness increases linearly with the amplitude of the applied ac potential. The reduction susceptibility of the passive film is also decreased with the amplitude of the applied ac. The photoelectrochemical measurements also indicate that the passive film is n type semiconductor and the photcurrent is decreased after ac modulation. It might be related to the surface chromium accumulation.
{"title":"Electronic structure study of ac modified passive film on stainless steel","authors":"T. Du","doi":"10.1179/000705902225002402","DOIUrl":"https://doi.org/10.1179/000705902225002402","url":null,"abstract":"Abstract The semiconductor properties, electronic structure and reduction susceptibility of passive films on AISI type 304 stainless steel in dilute sulphuric acid solutions have been studied by electrochemical impedance spectroscopy measurements, Mott-Schottky analysis and the photoelectrochemical technique. The passive film shows features of an amorphous or highly disordered n type semiconductor. The donor level is in the range of 1026-1027 m-3 and increases with the amplitude of ac potential. The passive film thickness increases linearly with the amplitude of the applied ac potential. The reduction susceptibility of the passive film is also decreased with the amplitude of the applied ac. The photoelectrochemical measurements also indicate that the passive film is n type semiconductor and the photcurrent is decreased after ac modulation. It might be related to the surface chromium accumulation.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"5 1","pages":"18 - 22"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79968041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002349
C. Batt, M. Robinson
Abstract A potentiostatic weight loss technique has been used to compare the corrosion rates of Weldox 700 high strength low alloy steel exposed to both natural and sterile sea water at potentials ranging from the free corrosion condition to - 1000 mV (SCE). Anodic polarisation curves with Tafel constants of 54 and 64 mV per decade were fitted to the data and the minimum levels of protection required to limit the corrosion rate to 0·001 mm per year were found to be - 770 and - 790 mV (SCE) in natural and sterile sea water, respectively. Lower corrosion rates occurred in filtered natural sea water than in sterile sea water but the highest rates were recorded on specimens ex posed to a seabed sediment. The reasons for this behaviour are discussed in terms of the biofilms and the numbers of sulphate reducing bacteria present on the surfaces.
{"title":"Cathodic protection requirements for high strength steel in sea water assessed by potentiostatic weight loss measurements","authors":"C. Batt, M. Robinson","doi":"10.1179/000705902225002349","DOIUrl":"https://doi.org/10.1179/000705902225002349","url":null,"abstract":"Abstract A potentiostatic weight loss technique has been used to compare the corrosion rates of Weldox 700 high strength low alloy steel exposed to both natural and sterile sea water at potentials ranging from the free corrosion condition to - 1000 mV (SCE). Anodic polarisation curves with Tafel constants of 54 and 64 mV per decade were fitted to the data and the minimum levels of protection required to limit the corrosion rate to 0·001 mm per year were found to be - 770 and - 790 mV (SCE) in natural and sterile sea water, respectively. Lower corrosion rates occurred in filtered natural sea water than in sterile sea water but the highest rates were recorded on specimens ex posed to a seabed sediment. The reasons for this behaviour are discussed in terms of the biofilms and the numbers of sulphate reducing bacteria present on the surfaces.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"13 1","pages":"31 - 36"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90450788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002321
A. Neville, X. Hu
Abstract Erosion-corrosion by liquid-solid impact results in damage on high alloy stainless steels where slurries are transported through pipes, valves, and pumps. It is well recognised that this damage is caused by a complex combination of mechanical (impact) and electrochemical (corrosion) processes. The synergy between erosion and corrosion is significant and depends on the nature of the materials and the aqueous environment. As part of a wider study investigating the mechanisms or erosion-corrosion of high alloy stainless steels, a series of electrochemical tests under multiple particle erosion-corrosion conditions and single impact conditions have been performed. In this paper the electrochemical behaviour under slurry erosion-corrosion and the transient electrochemical response under single impact of three stainless steels (UNS S31254, UNS S32654, and UNS S32750) is assessed. The depassivation and repassivation characteristics of the surface are characterised and these results are discussed in relation to the overall performance of the materials under erosion-corrosion conditions.
{"title":"Assessment of electrochemical response from high alloy stainless steels during slurry impingement and single impacts to improve understanding of erosion–corrosion","authors":"A. Neville, X. Hu","doi":"10.1179/000705902225002321","DOIUrl":"https://doi.org/10.1179/000705902225002321","url":null,"abstract":"Abstract Erosion-corrosion by liquid-solid impact results in damage on high alloy stainless steels where slurries are transported through pipes, valves, and pumps. It is well recognised that this damage is caused by a complex combination of mechanical (impact) and electrochemical (corrosion) processes. The synergy between erosion and corrosion is significant and depends on the nature of the materials and the aqueous environment. As part of a wider study investigating the mechanisms or erosion-corrosion of high alloy stainless steels, a series of electrochemical tests under multiple particle erosion-corrosion conditions and single impact conditions have been performed. In this paper the electrochemical behaviour under slurry erosion-corrosion and the transient electrochemical response under single impact of three stainless steels (UNS S31254, UNS S32654, and UNS S32750) is assessed. The depassivation and repassivation characteristics of the surface are characterised and these results are discussed in relation to the overall performance of the materials under erosion-corrosion conditions.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"7 1","pages":"43 - 47"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88209670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-02-01DOI: 10.1179/000705902225002394
M. Arshadi, M. Hosseini, M. Ghorbani
Abstract The inhibition effects of 3,5 bis (2-pyridil) 4-amino 1,2,4 triazole (NBTA) and 1-10 phenantrolin (PHEN) , on corrosion of mild steel in acid solutions, (sulphuric acid and hydrochloric acid) were studied. The Tafel polarisation and ac impedance techniques were employed. Results obtained reveal that both compounds are relatively good inhibitors. The inhibition efficiencies of NBTA are higher in hydrochloric acid than in sulphuric acid. This has been attributed to the synergistic effect of chloride ions present in hydrochloric acid. The mechanism of inhibition of PHEN is believed to be owing to the formation of insoluble chelates between the organic molecules and atom/ion on the metal surface. The adsorption of NBTA is believed to occur through the formation of an iron-nitrogen coordinate bond. The adsorption isotherms were also determined and found to be of the Langmuir type.
{"title":"Inhibition effect of 3,5 bis (2-pyridil) 4-amino 1,2,4 triazole and 1-10 phenantrolin on corrosion of mild steel in acid solutions","authors":"M. Arshadi, M. Hosseini, M. Ghorbani","doi":"10.1179/000705902225002394","DOIUrl":"https://doi.org/10.1179/000705902225002394","url":null,"abstract":"Abstract The inhibition effects of 3,5 bis (2-pyridil) 4-amino 1,2,4 triazole (NBTA) and 1-10 phenantrolin (PHEN) , on corrosion of mild steel in acid solutions, (sulphuric acid and hydrochloric acid) were studied. The Tafel polarisation and ac impedance techniques were employed. Results obtained reveal that both compounds are relatively good inhibitors. The inhibition efficiencies of NBTA are higher in hydrochloric acid than in sulphuric acid. This has been attributed to the synergistic effect of chloride ions present in hydrochloric acid. The mechanism of inhibition of PHEN is believed to be owing to the formation of insoluble chelates between the organic molecules and atom/ion on the metal surface. The adsorption of NBTA is believed to occur through the formation of an iron-nitrogen coordinate bond. The adsorption isotherms were also determined and found to be of the Langmuir type.","PeriodicalId":9349,"journal":{"name":"British Corrosion Journal","volume":"5 1","pages":"76 - 80"},"PeriodicalIF":0.0,"publicationDate":"2002-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81214610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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