Thesis (PhD)--University of South Australia, 2002.

Thesis (PhD (Metallurgical Engineering))--University of South Australia, 1997

Thesis (PhD (Metallurgical Engineering))--University of South Australia, 1997

Thesis (Ph.D.)--University of Wollongong, 2003. / Typescript. Bibliography: leaf 288-292.

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 139-148).

No description available.

This research focused on the surface modification and interfacial profile studies of a siloxane modified polyimide, BDS [BTDA (3,3\4.4'~ benzophenonetetracarboxylic dianhydride) ~ DDS (3.3'~diaminodiphenyl sulfone) - PSX (polydimethylsiloxane) copolymer], used as a coating material. The BDS coating surface can be modified by pretreatment in an alkaline solution. This surface pretreatment etched away the top siloxane surface layer, activated the surface by exposing and creating polar functional groups, particularly carboxylic acid groups, and roughened the surface. These changes on the coating surface significantly improved the wettability and the strength of the bond between the coating surface and a polar adhesive. Interfacial composition profiles were obtained from angular dependent X-ray photoelectron spectroscopy and Auger electron spectroscopy. Two kinds of interphases were found near the bond line of the coating/metal substrate. One was a component gradient interphase which was formed by component segregation of the BDS copolymer. The component gradient was different on different metal oxide surfaces with the siloxane interfacial excess in the order of AI > Ti > Zn. The relative acidities of the metal oxide surfaces were characterized by poly(vinyl chloride) adsorption tests which were quantified by XPS measurements. The relative acidities were found in the order of AI > Ti > Zn. Therefore, the cause for the BDS component segregation was suggested to be the influence of acid·base interactions between components of the BDS copolymer and the metal surface oxides. The other kind of interphase was a polymer-metal oxide mixture interphase which formed on penetration of the BDS copolymer solution into porous aluminum surfaces. / Master of Science

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 1993 / The formation of VC, NbC, and Cr-carbide coatings on steels immersed in molten borax baths containing carbide-forming constituents has been known for some time. A study was made of the formation of carbide coating on steel specimens treated in molten borax cont.ad.Lnr.q ferro-vanadium and V20S as bath additives. The prevalence of oxidizing or reducing conditions in the bath was found to playa decisive role in the formation of the VC layer. The influence of treatment factors such as time, temperature, and bath composition on the thickness of the coating was investigated. A detailed investigation into the behaviour of baths containing V205 and Al was carried out in this regard. Microstructural examination of coated specimens was performed using optical and electron microscopy. Microhardness tests, X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses were carried out in order to characterise the layers produced. The corrosion behaviour of the vanadf.um carbide coating was evaluated by accelerated electrochemical means. Samples of mild steel and EN9(O.5% C) steel were treated for various lengths of time in order to obtain coatings of various thicknesses. The corrosion resLst.ance of the carbide coating was found to be superior to that of the untreated base alloys. Five diffet"ent tool steel materials were a.lso treated. Microscopy examination and hardness testing of the VC coated tool steels was performed in order to assess the effects of treatment by this process on the bas~ material. The austenitizing temperature and the nature of the carbides in the matrix of the tool steels was found to play an important role in this respect. / MT2017

No description available.