摘要:

AbstractWe report on the atmospheric corrosion of different cast statue bronzes in humid air containing ppb levels of SO2and SO2+NO2. In addition, copper, tin, zinc, and lead samples were studied in these environments. The samples were exposed to synthetic atmospheres with careful control of pollutant concentrations, relative humidity and flow conditions. Deposition of SO2was studied using on‐line gas analysis. The weight gain was registered after four weeks exposure, and corrosion products were analysed by Electron Probe Micro Analyser (EPMA), X‐ray diffraction (XRD), and Fourier Transform Infrared spectroscopy (FTIR).The synergistic effect of SO2and NO2was remarkable on all bronze materials examined. The weight gain was correlated to alloy composition. Thus, high zinc and low lead content resulted in the greatest weight gain, while high tin content favoured a low weight increase. Lead exhibited a rapid deposition of SO2followed by zinc and copper, while tin was unreactive towards SO2. There was no measurable indication that microstructure influenced corrosion.The corrosion product morphology found in SO2+NO2environment indicated a localised type of attack. The anodic sites were covered by a tin‐rich corrosion product close to the metal. Oxidation of soluble divalent tin by O2at the anodic sites to form insoluble SnO2– xH2O, is suggested to explain the corrosion protection afforded by alloying with tin. Tin was enriched in the corrosion products while no lead was found. The zinc/copper relation was higher in the corrosion products than in the alloy comp

ISSN:0947-5117    

DOI:10.1002/maco.19970481102

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe corrosion behavior or commercial Fe ana Co base alloys and Fe‐Cr model alloys with different contents of Co and/or Mn was investigated by continuous exposure tests in the presence of a thin carbonate film. All alloys studied form multi‐layered corrosion scales consisting of outer Li containing oxides and inner Cr rich oxides, i.e. spinels or LiCrO2. The LiCrO2is formed on alloys with high Cr contents (≤ 20 wt.%), whereas mixed (Fe,M)3‐xCrxO4spinels (M = Co, Mn, Ni) were found on alloys with lower Cr content (15–20 wt.%). Insoluble Cr containing oxides occur only in the inner layers of the corrosion scale, whereas on the surface of corroded specimens soluble chromates were detected. Alloys with Mn contents greater than 15 wt.% form Mn2O3in the initial stages of the experiments, this oxide reacts with the melt and formation of Li2MnO3takes place. In exposure tests up to 500 h Fe‐Cr alloys with low contents of Mn and Co (10 wt.% Co or Mn) form iron rich oxides (LiFeO2and LiFe5O8) with varying amounts of dissolved Mn or Co. In the later corrosion stages outward diffusion of Mn and/or Co takes place and LiCoO, and Li2MnO3are formed on top of LiFeO2, whereby the concentration of Mn and/or Co in the inner layers (LiFeO2and spinel) decreases. The outer Li containing oxides LiFeO2, LiCoO2and Li2MnO3are nearly insoluble in the melt and when present at the surface protect the metallic material from further corrosive attack. Fe‐Cr model alloys containing Co and Mn form multi‐layered corrosion layers after 2000 h of exposure. These layers consist of four oxides in the following sequence from the metal‐scale to the scale‐melt interface: (Fe,Cr,Co,Mn)3O4spinel, LiFeO2

ISSN:0947-5117    

DOI:10.1002/maco.19970481103

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractChromate pigmented paints are commonly used in painting the aluminium parts of the aircrafts. This study is directed to find an alternative inhibitor in place of chromate the most widely used inhibitor in aircraft paints. In that effect sodium benzoate, polyacrylic acid (PAA), strontium chloride, cerium chloride, malic acid, glycin, cobalt sulphate, pyrrol, and quartamin T (alkyl three methyl ammonium chloride) were tried in place of Na2CrO4. The anodic and cathodic polarisation curves were recorded and weight loss measurements were carried out in 0.1 M NaCl solutions with and without inhibitor. Quartamin T, pyrrol and PAA which were observed to provide satisfactory inhibition effect were added to the polyurethane based paints used in the aircraft industry and the Al (2024) alloy painted with this paint was subjected to electrochemical corrosion tests in 0.1 M NaCl. Pyrrol and quartamin T containing paints were observed to give results as good as those obtained with chromate containing paints.

ISSN:0947-5117    

DOI:10.1002/maco.19970481104

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractAluminiumpigmente korrodieren in Gemischen aus Wasser und Butylglykol bei pH 8 bzw. 10 unter Wasserstoffentwicklung, was gasvolumetrisch leicht gemessen werden kann. Diese Korrosionsreaktion kann durch Zusatz von Estern der Gallussäure (Gallate) inhibiert werden. Dabei steigt die korrosionsinhibierende Wirkung der Gallate mit zunehmender Kettenlänge des Esteralkohols; dieser Zusammenhang zwischen dem chemischen Aufbau der Inhibitoren und der entwickelten Menge an Wasserstoff läßt sich mit Hilfe einer Exponential funktion mathematisch korrelieren. Mit dem besten Inhibitor Dodecylgallat, das ein Amphiphil mit zur Chelatkomplexbildung befähigter Kopfgruppe ist, wurden Schutzwerte um 99% erreicht. Um die Vermutung, das derartige Amphiphile allgemein gute Inhibitoren für die untersuchte Korrosionsreaktion sind, zu erhärten, wurde als zweites Beispiel das Amphiphil Agaricinsäure (α‐Hexadecylcitronensäure) im Vergleich zur Kopfgruppe Citronensäure geprüft; auch hier inhibierte das Amphiphil die Korrosionsreaktion des Aluminiumpigments besser als die Kopfg

ISSN:0947-5117    

DOI:10.1002/maco.19970481105

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970481106

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper presents the results obtained in a 5 year study of the galvanic protection afforded to the base steel by a 55 % Al‐ZnMade in Spain by CSI Planos under the trademark Algafort which has been licensed by BIEC International, Inc. This product is commercially available in U.S.A. under the trademark Galvalume.coating and its comparison with a galvanized coatin., in different types of atmospheres. While both coatings hardly supply cathodic protection (CP) in rural and urban atmospheres, in marine and industrial type atmospheres they present excellent galvanic performance, which is conditioned only by the duration of the anodic material on the steel substrate. This duration is considerably greater in the 55% Al‐Zn coating, due to its lower corrosion rate in the atmosph

ISSN:0947-5117    

DOI:10.1002/maco.19970481107

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970481108

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970481109

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970481112

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970481113

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY