ISSN:0947-5117    

DOI:10.1002/maco.19940450514

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19940450515

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19940450516

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19940450517

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19940450521

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe stress corrosion cracking (SCC) behaviour of aluminium alloy sheet was investigated in the long transverse direction using the slow strain rate testing technique. The synthetic environment used was an aqueous solution of 3% NaCl + 0.3% H2O2. No indications of SCC sensitivity are observed for the alloys 2024‐T351, 8090‐T81, and 2091 CPHK‐T8X. The alloys 2091 T8X and 6061‐T4 are found to be susceptible to intergranular stress corrosion cracking. At strain rates below 4 · 10−7s−1, the slow strain rate testing technique indicates a slight SCC sensitivity with alloy 6013‐T6. Fractography reveals transgranular stress corrosion cracking. Transgranular stress corrosion cracking is also observed with 6061‐T4 specimens which are dynamically strained at strain rates below 5 · 10−7s−1. Aqueous 3% NaCl solution with hydrogen peroxide addition promotes pitting and intergranular corrosion. The loss of ductility caused by these corrosion processes interferes with the evaluation of the results of the slow strain r

ISSN:0947-5117    

DOI:10.1002/maco.19940450502

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractCoated sintered steel parts were subjected to corrosion resistance tests and electrochemical characterization. A wide range of industrially produced coatings, covering all the main proposed treatments, were analysed.Conventional corrosion tests were employed to compare corrosion resistance, whereas electrochemical test methods were used with the aim of giving a better understanding of the mechanisms which control corrosion processes and the corrosion rate. In particular, electrochemical impedance spectroscopy showed to be very helpful in allowing the monitoring of corrosion behaviour as a function of testing time, without introducing significant electrical perturbation on the examined system.The experimental results of this study showed that sintered steel protection by coating is possible if the process is very well controlled, however, defects in the coating can always be present due to the substrate porosity. With this fact in mind the use of sacrificial coatings is recommendable due to the possibility of a cathodic protection corresponding to coating defects.

ISSN:0947-5117    

DOI:10.1002/maco.19940450503

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractBlättchenförmige Aluminiumpigmente (Al‐Gehalt>99,5%) werden in einem alkalischen Gemisch aus Wasser und Butylglykol im Verhältnis 9: 1 korrodiert. Durch Chelatkomplexbildner wie Citronensäure bzw. Polyacrylsäure kann diese Korrosionsreaktion inhibitirt werden. Der zeitliche Verlauf der Korrosionsreaktion läßt sich durch gasvolumetrische Bestimmung des entstehenden Wasserstoffs und zusätzlich, beim Einsatz der genannten Inhibitoren, durch Messung der elektrischen Leitfähigkeit der Lösung verfolgen.Die Korrosionsreaktion besteht im wesentlichen aus zwei Teilschritten:1In derLatenzphase, in der kaum Korrosion stattfindet, werden wahrscheinlich die Schutzschichten, (natürliche Oxidschicht bzw. durch Reaktionsprodukte von Inhibitor und Aluminium verstärkte Schichten) aufgelöst.2Danach kommt es zur eigentlichen sehr schnellenKorrosionsreaktion.Es wurde nachgewiesen, daß sich Änderungen des pH‐Wertes bzw. der Zusatz von carboxygruppenhaltigen Inhibitoren nur auf die Länge der Latenzphase auswirken; danach läuft die Korrosionsreaktion unabhängig von den untersuchten Bedingungen in e

ISSN:0947-5117    

DOI:10.1002/maco.19940450504

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAn experimental statistical plan is utilized to solve corrosion problems of a section of an industrial plant for the production of caprolactam, consisting of a multistage flash evaporator entirely constructed in AISI 316L (X2CrNiMo 17 12 2). Preliminary tests show that the nitrates or acidity due to the sulfuric acid do not influence the corrosive phenomena and confirmed the positive, though costly, effect of adding hydroxylamine sulfate (SI) in the evaporator feed. An experimental plan was prepared to diminish the cost and dosage of SI in the system: the experimental statistical approach has allowed us to minimize the number of tests required in order to define the system rapidly and adequately, and to optimize the required amount of SI.The data processed have been obtained in a two‐step experimental plan that allowed us to establish a relationship between the logarithm of critical corrosion current (icr) and the concentrations of some evaporator feeding components. In addition, it has been possible to clarify certain corrosion effects and to reduce the SI addition up to 1.4 g/l, thereby optimizing the chemical system and considerably reducing maintenance costs. A plausible explanation of the related effects of some of the feeding components is also propose

ISSN:0947-5117    

DOI:10.1002/maco.19940450505

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19940450506

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY