摘要:

AbstractIn einem Überblick über die historische Entwicklung zur Bestimmung des Langzeitverhaltens von Kunststoffrohren and der Untersuchungen zur Beurteilung der Widerstandsfähigkeit der Kunststoffe gegen Chemikalieneinwirkung werden these Methoden beschrieben.Die Zeitstandinnendruckprüfung von Rohren bei gleichzeitiger Chemikalieneinwirkung wird erläutert und die bisher ermittelten Versuchsergebnisse nach der Prüfung mit konstanten Drucksteigerungsraten entsprechend ISO 8584 T2 mitgeteilt [1].Ein Vergleich dieser Prüfergebnisse mit den Ergebnissen aus konventionellen Zeitstandinnendruckversuchen unter konstanten Prüfspannungen entsprechend ISO 8584 T1 [2] wird vorgenommen und eine erste Bewertung der Drucksteigerungsmethode für die Bestimmung von chemischen Resistenzfaktoren durc

ISSN:0947-5117    

DOI:10.1002/maco.19970480502

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe metal‐metalloid glass (Fe, Cr)80(P, C, Si)20was investigated in aqueous solutions which contain high quantities of NaCl (3 M). For comparison we use a solution with 1.5 M Na2SO4. These solutions reach from the strong acid area (0.5 M H2SO4) to the strong alkaline region (1 M NaOH). The corrosive properties of the metal‐metalloid glass were determined at 25°C and 5°C.By the use of electrochemical methods it was possible to estimate the long time corrosive properties. Therefore current‐potential‐curves were determined by the use of a potentiodynamic technique. Starting from this curves it was possible by use of the tafel plot method or the determination of the polarisation resistance to. calculate an annual pull down of the metallic glass. For these electrochemical experiments we used the glass ribbons as electrodes and we measured under rotating conditions.The determined values of the annual pull down vary in a large region. The highest rate (44 mm/a) was calculated for an acid chloride containing solution at a temperature of 50°C. The lowest pull down rate (≈ 0.3 μm/a) is obtained in the alkaline solution at room temperature. In the alkaline area there is no difference between the addition of NaCl or Na2SO4.The treated glass fibres were characterised by the use of Scanning Electron Microscopy (SEM) and

ISSN:0947-5117    

DOI:10.1002/maco.19970480503

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe electrochemical behaviour of the Zr55Cu30Al10Ni5amorphous alloy prepared as cylindrical bulk samples with 7 mm diameter has been investigated. Cyclic potentiodynamic polarization measurements carried out on the cross section areas of the samples in air‐saturated and nitrogen‐purged sulphate and hydroxide solutions, respectively, show that the alloy rapidly forms protective passive layers with low electron conductivity which are stable in a wide pH‐value and potential range. Anodic layer formation reactions are characterized. In chloride containing electrolytes a pitting corrosion susceptibility of the bulk material exists. The effect of crystalline defects as active sites for the initiation of localized corrosion processes is critically disc

ISSN:0947-5117    

DOI:10.1002/maco.19970480504

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractSulphidation of an ordered bee alloy having the nominal composition Fe‐40 at.% Al was studied at temperatures of 1073‐1273 K in hydrogen/hydrogen sulphide mixtures at sulphur pressures of 10−5– 10−2Pa. The sulphidation runs were followed thermogravimetrically. Phase and chemical composition of the sulphide scales and the scale morphologies were determined by means of XRD, EDX, EPMA and SEM. The sulphidation runs showed a relatively fast uptake of sulphur at the beginning followed by a gradual slowdown. The estimated parabolic rate constants for the second stage of the reaction were of the order of 10−12– 10−11kg2/m4s, i. e. comparable to the oxidation rates of alumina formers in the same temperature range. The initial faster growth of the sulphide scale was attributed to the formation of iron‐aluminum sulphospinel whereas the second stage to the development of aluminum sulphide at the allo

ISSN:0947-5117    

DOI:10.1002/maco.19970480505

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractA high sensitive detection method allows the direct determination of Pt2+/Pt4+within a concentration range of ng/1 (ppt). The procedure was used to establish the development of soluble platinum species during constant or dynamic polarisation of platinum electrodes in phosphate buffered saline solution.Platinum showed some properties of a passive metal. In the passivated state the dissolution was influenced by a surface film. Furthermore a soluble platinum species was found to be produced during the reduction of the surface oxide. These results confirmed by direct evidence the conclusions of earlier investigations concerning the corrosion of platinum based on electrochemical measurements.

ISSN:0947-5117    

DOI:10.1002/maco.19970480506

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractCopper tubes are considered as material of choice for most domestic and institutional plumbing requirements. However, to a few instances problems have arisen which were shown to involve microbiological activity. The BRITE/EURAM Project “New Types of Corrosion Impairing the Reliability of Copper in Potable Water Caused by Microorganisms” (Contract‐No. BREU‐CT 91‐0452) was launched to examine the interactions between microorganisms and their secreted products and a copper tube surface involving a cross‐disciplinary consortium. A review of this project is reported in this contribution.Based upon chemical analysis of biofilms from failed copper tubes, it was possible to develop model biopolymers of defined composition and well characterised surface adsorption properties to establish suitable electrochemical test procedures. Culture biopolymers showing similar chemical compositions could be produced from a range of copper‐pitting‐associated bacteria. It was possible to demonstrate cation selective behaviour by layers of these relevant model and culture biopolymers.Two linked copper electrodes, one hare and the other coated with a cation selective biopolymer, were shown to establish a corrosion element. The covered areas acted as the cathode whilst the bare areas were anodic. This was also seen in single metal samples with disrupted polymer coatings giving “bare” patches.In anodic areas the corrosion follows a chloride induced mechanism leading to repassivation of the surface. This could also be demonstrated in the original potable water taken from an institutional building affected by Microbially Influenced Corrosion (MIC). Sulphate ions inhibit this expected passivation process. The basic corrosion process appears to follow the chloride model, but this can become overshadowed by the effects of additional anions such as sulph

ISSN:0947-5117    

DOI:10.1002/maco.19970480507

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractA case study is presented about the failure of a stainless steel blade reinforcing band in a steam turbine. The inspection results and analysis of samples of material are discussed. Being pitting corrosion and cracks the main defects found, a study of chemical composition and heat treatment state of the steel is made and findings are related to type of failure.

ISSN:0947-5117    

DOI:10.1002/maco.19970480508

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970480509

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970480512

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0947-5117    

DOI:10.1002/maco.19970480513

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY