Zinc and zinc alloy composite coatings for corrosion protection and wear resistance PDF
Preview Zinc and zinc alloy composite coatings for corrosion protection and wear resistance
Loughborough University Institutional Repository Zinc and zinc alloy composite coatings for corrosion protection and wear resistance ThisitemwassubmittedtoLoughboroughUniversity’sInstitutionalRepository by the/an author. Additional Information: • A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University. Metadata Record: https://dspace.lboro.ac.uk/2134/10888 Publisher: (cid:13)c J.T. Tuaweri Please cite the published version. This item was submitted to Loughborough University as a PhD thesis by the author and is made available in the Institutional Repository (https://dspace.lboro.ac.uk/) under the following Creative Commons Licence conditions. For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ . i • . •. ', I I .. Lo'!ghbprough ...• • UmverSIty '!, University Library -----------------------------., ,i :r.·: .... ·.. .. ·.. · =E.l./?\~.£&Lr .. AuthorlFiling Title .... ........... .................................. ................................ .... ......,". : . .. ~ I ........ Class Mark ...........................• ! ..................•....... -: ----------------- .. ' Please note that fines are charged on ALL overdue items. 0403271134 IIIIII IIIIIIII III II II III II III III III III IIIII Zinc and zinc alloy composite coatings for corrosion protection and wear resistance by Tuaweri, Johnnie Tolumoye M.Se (Eng.) (Donetsk) A doctoral thesis submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University Supervisor: Dr. G.D.Wi1cox Institute of Polymer Technology and Materials Engineering Loughborough University December 2005· " © by Tuaweri, J.T U Loughborough Uni\'C!I'sity Pilkinglllll Library Date ~£P-r 2..00b -,- Class ~~~ 01t032:.-=t1 \ 3~ SYNOPSIS Zinc and its alloys are among the most widely utilised metallic coatings for the sacrificial protection of steel. Although excellent in this mode of protection, these coatings are often less durable when subjected to environments of combined wear and corrosion due to their intrinsic relative softness and ductility. A possible and fast growing way of improving the durability of these coating is by the codeposition of inert particles into the zinc and zinc-alloy matrix. The main aim of this research was therefore to improve the durability of zinc and zinc-nickel coatings by the incorporation of inert particles via electrolytic codeposition methods. The first five chapters of this thesis comprise literature review on the electrodeposition of zinc, its alloys and composite electrodeposition in general. A major part of which was dedicated to the review of various conventional methods and parameters such as current density, agitation, temperature, solution composition, bath additives and pH usually investigated in electrodeposition. The experimental work was principally based on DC electrodeposition and was aimed at understanding the deposition behaviour of zinc and zinc-nickel electrodeposition baths, conditions which influence them and solution compatibility to the introduction of silica particles A systematic study on the deposition behaviour of both zinc/silica and zinc-nickel/silica composite baths was carried out with particular interest on the rate of particle incorporation and the influence of particles on zinc-nickel alloy deposition. The complimentary codeposition behaviour of the nickel and silica particles was observed. The influence of bath additives such as N,N Dimethyldodecylamine (NND) and sodium nitrate on the rate of silica incorporation was also studied. Both additives were found to improve the rate of particle incorporation for the zinc/silica. The morphologies and compositions of the coatings were analysed with the use of SEM and FEGSEM. I Corrosion performance studies were carried out in a neutral salt spray chamber and linear polarisation resistance methods used to determine barrier corrosion properties of the coatings. Anodic polarisation studies were also carried out. The results show an improvement in the corrosion performance of these coatings with the addition of silica particles Reciprocating wear tests were used to determine the wear behaviour of the coatings in terms of weight loss. Improvement in wear resistance was not observed in the zinc/silica coatings probably due to the high content of silica in the coatings. Lower silica contents may be required for the desired improvements. However, there were obvious improvements in the wear behaviour of the zinc-nickel/silica coatings due to the presence of the silica particles. Keywords Composite, electrodeposition, zinc, zinc-nickel, N,N Dimethyldodecylamine, sacrificial coatings, corrosion resistance, wear resistance. 11 ACKNOWLEDGEMENTS I would like to express my deepest gratitude to my supervisor, Dr. G.D. Wilcox for his concern, support, encouragement, patience and dedication in the supervision of this research work. Thanks also to Professor R. Faulkner my director of research. I also want to thank my beloved wife and children, Pastor Lizzy, Toboulayefa, Gloria, Woyengipreye and Ebiegberi for their prayers, love and sacrifice throughout the period of this research work. Special thanks to my parents Mr 1.0. Tuaweri and Mrs. M.P. Tuaweri for the love and sacrifice for my education. I also want to thank my sister and her husband Mrs Kens Walson and Mr Ken Walson for their love and support over the years. I wish to specially thank Dr. Keming Chen for his invaluable discussions and support at all stages of this research work. Many thanks also to Mr. I.S. Bates, Mr. F. Page for their help with the FEGSEM and SEM analysis. Thanks also to my colleagues and friends on study fellowship at Loughborough University, Mr. Promise Mebine, Mr Emmanuel Adigio, Allen Ekubo, Mrs Ibiba Harry, Mrs Rhoda Gumus, Mr Osaisai and Mr. Cornelius Odigi for their encouragements. My gratitude also extends to all the staff and students of IPTME for the friendly and supportive environment during the period of this research. These acknowledgements are also extended to all that may have been directly or indirectly involved in this research that I happen to have overlooked. Last, but not the least, I wish to thank the Bayelsa State Government for funding this research work. III Dedication This work is dedicated to God almighty for ''The earth is the Lord's, and the fullness thereof; the world and they that dwell therein" (Psalm 24:1). IV
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