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dc.contributor.authorDadvand, Nazila.en_US
dc.date.accessioned2014-10-21T12:38:03Z
dc.date.available2014-10-21T12:38:03Z
dc.date.issued2002en_US
dc.identifier.otherAAINQ77589en_US
dc.identifier.urihttp://hdl.handle.net/10222/55879
dc.descriptionOne of the major drawbacks to using aluminum parts in automotive applications is poor wear resistance. Various techniques have been used to address this concern and the purpose of this work was to produce a hard and wear resistant Ni-B coating on AA6061. This was accomplished using an electroless nickel-boron (EN-B) bath preceded by a protective zincating/electroless nickel-phosphorus pretreatment. The experimental parameters for Ni-P and Ni-B baths were optimized, and the effect of various experimental parameters on the plating rate were examined. The phosphorus and boron contents of each deposit were measured using electron probe microanalysis (EPMA) and atomic absorption spectroscopy (AAS), respectively; the surface morphology of each coating was examined using scanning electron microscopy (SEM). Results showed that the surface morphology of the Ni-B coating varies with that of the intermediate EN-P coating. In turn the surface morphology of the intermediate EN-P coating depends on the thickness of the coating and the EN-P plating bath condition.en_US
dc.descriptionAs well the corrosion behaviour of electroless nickel-phosphorus (EN-P) coatings with phosphorus content ranging from 2 to 12.5 w% was investigated using potentiodynamic (PT) and cyclic voltammetry (CV) techniques in 0.5 M sodium hydroxide. It was found that although the corrosion resistance of EN-P coatings generally decreased with an increase in phosphorus content the trend was observed only for samples where the difference in the P content was large. For example, a very low P EN coating (2 w%) was more resistant in alkaline solution than two medium P (6.5, 8 w%) samples, and these in turn were more resistant than the high P (12.5 w%) coated sample. However, when comparing the 6.5 and 8 w% samples the higher P content showed more resistance. This behaviour may be explained in terms of the two counteracting effects, activation and inhibition, of phosphorus on corrosion resistance. The activating effect is due to the lower protectiveness of the passivating film because of its lower thickness. As the P content increases, the inhibiting effect increases as a result of phosphate formation. As well, the corrosion products and cyclic voltammetric behaviour of the EN samples varied with bath pH.en_US
dc.descriptionFinally the corrosion behaviour of electroless nickel-boron (EN-B) coatings with boron content of 6 w% was also investigated using potentiodynamic technique in 0.5M sodium hydroxide, and the results were compared with those of nickel-phosphorus coating with phosphorus content of 6 w%.en_US
dc.descriptionThe overall results are discussed with a view to providing an optimum process to inhibit the corrosion of AA6061.en_US
dc.descriptionThesis (Ph.D.)--DalTech - Dalhousie University (Canada), 2002.en_US
dc.languageengen_US
dc.publisherDalhousie Universityen_US
dc.publisheren_US
dc.subjectEngineering, Metallurgy.en_US
dc.subjectEngineering, Materials Science.en_US
dc.titleInvestigation of the corrosion behaviour of electroless nickel-boron and nickel-phosphorus coatings in basic solutions.en_US
dc.typetexten_US
dc.contributor.degreePh.D.en_US
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