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The research investigated the application of continuous coaxial laser cladding by powder injection as a surface treatment or coating process. The investigation aimed to establish the relationship between a change in the main laser cladding process variables and the geometry and characteristics of an Al-20wt-Si single pass clad layer formed on an Al 1370-F substrate using a Nd:YAG laser. The main process variables considered were: laser power, laser scanning velocity and the powder feed rate. The relationship between a change in the main laser cladding process variables and the geometry and characteristics of the clad layer was established by statistically analysing the variation in the process response with a change in the main laser cladding process variables. The process variables were varied based on a full-factorial, experimentally optimized test matrix. The clad geometry which is mainly defined by: the clad height, width, clad aspect ratio, depth of alloy penetration, and the clad root angle/wetting angle was investigated. In addition to the clad geometry several clad characteristics were investigated such as the dilution of the clad layer in the substrate material, the Vickers microhardness and microstructure of the clad crosssection, the powder efficiency of the process and the amount of visible defects. The study successfully established the relationship between the main laser cladding process variables and the clad geometry and characteristics. The secondary objective of establishing a suitable processing window by considering the relationship mentioned above was only partially met since it is believed that further refinement of the experimental cladding test setup and therefore also the experimental variable test levels is required.

Qin Shuijie. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 109-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

"27 September 2003." / Includes bibliographical references (leaves xix-xxv ; v. 1) / 2 v. : ill., plates (some col.), photos (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Chemical Engineering and School of Mechanical Engineering, 2004

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With the progress of microfabrication and nanofabrication technologies, there has been a reawakened interest in the possibility of controlling the propagation of light in various materials periodically structured at a scale comparable to, or slightly smaller than the wavelength. We can now engineer materials with periodic structures to implement a great variety of optical phenomena. These include well known effects, such as dispersing a variety of wavelength to form a spectrum and diffracting light and controlling its propagation directions, to new ones such as prohibiting the propagation of light in certain directions at certain wavelengths and localizing light with defects in some artificially synthesized dielectric materials. Advances in this field have had tremendous impact on modern optical and photonic technologies. This doctoral research was aimed at investigating some of the physics and applications of periodic structures for building blocks of the optical communication and interconnection system. Particular research emphasis was placed on the exploitation of innovative periodic structure-based optical and photonic devices featuring better functionality, higher performance, more compact size, and easier fabrication. Research topics extended from one-dimensional periodic-structure-based wavelength-division-multiplexing (WDM) optical interconnects (beam wavelength selection devices), and liquid crystal beam steerers (beam steering devices), to two-dimensional periodic-structure-based silicon photonic-crystal thermo-optic and electro-optic modulators (beam switching devices). This research was specifically targeted to seek novel and effective solutions to some long-standing technical problems, such as the limited wavelength coverage of coarse WDM devices, small bandwidth of highly dispersed dense WDM devices, low deflection efficiency of high-resolution liquid crystal beam steerers, slow switching speed, large device size, and high power consumption of silicon optical modulators, among others. For each subtopic, research challenges were presented and followed by the proposed solutions with extensive theoretical analysis. The proposals were then verified by experimental implementations. Experimental results were carefully interpreted and the future improvements were also discussed.

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