This thesis focuses on the volatile and hygroscopic properties of mixed aerosol species. In particular, the influence organic species of varying solubility have upon seed aerosols. Aerosol studies were conducted at the Paul Scherrer Institut Laboratory for Atmospheric Chemistry (PSI-LAC, Villigen, Switzerland) and at the Queensland University of Technology International Laboratory for Air Quality and Health (QUT-ILAQH, Brisbane, Australia). The primary measurement tool employed in this program was the Volatilisation and Hygroscopicity Tandem Differential Mobility Analyser (VHTDMA - Johnson et al. 2004). This system was initially developed at QUT within the ILAQH and was completely re-developed as part of this project (see Section 1.4 for a description of this process). The new VHTDMA was deployed to the PSI-LAC where an analysis of the volatile and hygroscopic properties of ammonium sulphate seeds coated with organic species formed from the photo-oxidation of á-pinene was conducted. This investigation was driven by a desire to understand the influence of atmospherically prevalent organics upon water uptake by material with cloud forming capabilities. Of particular note from this campaign were observed influences of partially soluble organic coatings upon inorganic ammonium sulphate seeds above and below their deliquescence relative humidity (DRH). Above the DRH of the seed increasing the volume fraction of the organic component was shown to reduce the water uptake of the mixed particle. Below the DRH the organic was shown to activate the water uptake of the seed. This was the first time this effect had been observed for á-pinene derived SOA. In contrast with the simulated aerosols generated at the PSI-LAC a case study of the volatile and hygroscopic properties of diesel emissions was undertaken. During this stage of the project ternary nucleation was shown, for the first time, to be one of the processes involved in formation of diesel particulate matter. Furthermore, these particles were shown to be coated with a volatile hydrophobic material which prevented the water uptake of the highly hygroscopic material below. This result was a first and indicated that previous studies into the hygroscopicity of diesel emission had erroneously reported the particles to be hydrophobic. Both of these results contradict the previously upheld Zdanovksii-Stokes-Robinson (ZSR) additive rule for water uptake by mixed species. This is an important contribution as it adds to the weight of evidence that limits the validity of this rule.

This thesis presents the results of a study focussed on the elucidation of the mechanisms responsible for determining the structural integrity of carbon coatings on ductile substrates. Through elucidation of these mechanisms, two different coating systems are designed; a multilayered coating and a functionally graded coating. While concentrating upon carbon coatings, the findings of this study are applicable to a broad range of hard coatings on ductile substrates. The thesis concludes with a chapter outlining a brief study of the effects of gold coatings on silicon under contact load at moderate temperatures to complement the major part of the thesis. Carbon coatings with differing mechanical properties were deposited using plasma enhanced chemical vapour deposition (PECVD), filtered assisted deposition (FAD) and magnetron sputtering deposition methods. Combinations of these techniques plus variation of deposition parameters enabled composite multilayered and functionally-graded coatings to also be deposited. Substrates were ductile metals; stainless steel and aluminium. Characterisation of the coating mechanical properties was undertaken using nanoindentation and nano-scratch tests. The same techniques were used to induce fracture within the coatings to allow subsequent analysis of the fracture mechanism. These were ascertained with the assistance of cross-sectional imaging of indents prepared using a focussed ion beam (FIB) mill and transmission electron microscopy (TEM) using specimen preparation techniques also utilising the focussed ion beam mill. A two dimensional axisymmetric finite element model (FEM) was built of the coating systems using the commercial software package, ANSYS. Substrate elastic-plastic properties were ascertained by calibrating load-displacement curves on substrate materials with the finite element model results. Utilising the simulation of spherical indentation, the distribution of stresses and the locations for fracture initiation were ascertained using finite element models. This enabled determination of the influence such factors as substrate mechanical properties, residual stresses in the coatings and importantly the variation of elastic properties of the different coating materials. Based upon the studies of monolithic coatings, simulations were undertaken on multilayer and functionally-graded coatings to optimise design of these coating types. Based on the results of the modelling, multilayered and functionally graded coatings were then deposited and mechanical testing undertaken to confirm the models. Three major crack types were observed to occur as the result of the spherical nanoindentation on the coatings; ring, radial and lateral cracks. Ring cracks were found to initiate from the top surface of the film, usually at some distance from the edge of the spherical contact. Radial cracks usually initiated from the interface between the coating and the substrate directly under the symmetry axis of indentation and propagated outwards in a non symmetrical star-like fashion. Lateral cracks formed either between layers in the multilayer coatings or at the interface with substrate. Ring and radial cracks were found to form upon loading whereas lateral cracks formed upon both loading and unloading depending upon the crack driving mechanism. Pop-in events in the load displacement indentation curve were found to be indicative of the formation of ring cracks, while the formation of the other types of cracks was not signified by pop-ins but rather by variations in the slope of the curve. The substrate yield strength was found to influence the initiation of all crack systems while compressive stresses in the coating were seen to only influence the formation of ring and radial cracks. However, it was also noted that the initiation of one form of crack tended to then hinder the subsequent formation of others. In multilayer coatings, the lateral cracks were suppressed, as opposed to the monolayer coating system, but a ring crack was observed. This drawback in the multilayer system was successfully addressed by the design of a graded coating having the highest Young??s modulus at the middle of the film thickness. In this coating, due to the graded nature of the elastic modulus, the stresses at the deleterious locations (top surface and interface) were guided toward the middle of coating and hence increased the load bearing capabilities. The effect of substrate roughness upon the subsequent surface roughness of the coating and also upon the fracture process of the coating during indentation was also investigated. For the coatings deposited on rough substrates, the radial cracks were observed to form initially and this eventfully delayed the initiation of ring cracks. Also the number of radial cracks observed at the interface was found to be proportional to the distribution of the interfacial asperities. In summary, the study elucidated the fracture mechanisms of monolayer, multilayer and graded carbon coatings on ductile substrates under uniaxial and sliding contact loading. The effects of the yield strength, surface roughness of the substrate, along with the residual stress and elastic modulus of the coatings on the fracture of coatings were investigated. The study utilised finite element modelling to explain the experiments observations and to design coating systems.

Thesis (Ph. D.)--Duke University, 2008. / Includes bibliographical references.

Thesis (Ph.D.)--Flinders University, Dept. of Chemistry. / Typescript bound. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 144-152).

Thesis (M.E.-Res.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references: leaf 226-238.

Thesis (M. Sc.)--University of Canterbury, 2009. / Typescript (photocopy). "June 2009." Includes bibliographical references (p. [113]-119).

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Ceramic and Materials Science and Engineering." Includes bibliographical references.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Collard, David M.; Committee Co-Chair: Garcia, Andres J.; Committee Member: France, Stefan; Committee Member: Ragauskas, Arthur; Committee Member: Temenoff, Johnna. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph.D.) - Carleton University, 2007. / Includes bibliographical references (p. 249-266). Also available in electronic format on the Internet.