TiN is used commercially as a wear resistant coating on cutting tools and as a diffusion barrier in microelectronics. TiN has gained increased interest as a material for MEMS, however there has been very little work carried out in the area of patterning and releasing TiN for use as a structural MEMS material. This thesis presents an investigation into the patterning and release of filtered arc deposited TiN thin films using surface micromachining techniques. Two novel strategies are presented for patterning TiN thin films and are achieved using excimer laser micromachining and photolithographic wet-etching. TiN was deposited onto single crystal Si and Cr and Cu sacrificial layers on Si. The use of Cr as a sacrificial layer was found to facilitate the best quality patterning of the TiN and hence the majority of the work involved using Cr sacrificial layers. TiN was deposited using partial filtration and full filtration and differences in the ability to selectively laser pattern the TiN from the Cr sacrificial layer are presented. Various analytical techniques were employed to investigate the origin of the difference in laser patterning the TiN thin films. The establishment of TiN and Cr as a novel material combination for surface micromachined MEMS was extended by etching the Cr sacrificial layer to facilitate the release of TiN stress-measurement structures. The major finding of this thesis is that filtered arc deposited TiN thin film on Cr can be used as a material combination to surface micromachine freestanding TiN structures as high quality patterning and etch selectivity can be achieved using both excimer laser micromachining and photolithographic wet-etching.

Thesis (Ph.D)--Technische Universiteit Eindhoven, 2006. / Title from title screen (viewed on Dec. 6, 2007). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

Thesis (M.S.)--University of Akron, 2004. / Title from Web page (viewed on Dec. 17, 2007). "December, 2004." Includes bibliographical references (p. 118-124).

Thesis (M.S.)--State University of New York at Binghamton, Department of Physics, 2006. / Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Anette M. Karlsson, Dept. of Mechanical Engineering. Includes bibliographical references.

Graduation date: 1998

Thesis (Ph. D.)--University of Rhode Island, 2006. / Typescript. Includes bibliographical references (leaves 126-134).

This dissertation describes the characterization of layer-by-layer silica and titania coatings deposited using a protamine-induced method. It was found that silica coatings were thinner and more porous than titania coatings. These coatings were functionalized by immobilizing modified Glucose oxidase during the layer-by-layer buildup. The enzyme was found to retain higher activity in silica versus titania, with full retention of activity observed in one configuration. Immobilization in both materials resulted in enhanced thermal stability and proteolytic protection. The enzyme-functionalized coatings were then modified by the immobilization of silver nanoparticles to the exterior, and this biological/inorganic composite was tested for its antimicrobial activity against E. coli and S. aureus. Against E. coli the composite worked in a synergistic fashion, showing more potent antimicrobial activity when compared to either agent used alone. The enzyme modification method was then extended to Laccase, which was immobilized to carbon nanotubes and characterized as a biocathode. Modified laccase returned a nearly two-fold higher current density versus the native enzyme. Finally, synthetic peptides were tested for their ability to adsorb to silica and titanium-oxide surfaces and subsequently deposit titanium-oxide coatings, in an effort to better understand the structure-function relationships of mineralizing peptides.

Coatings are often used on critical components in machines and engines to reduce wear and to provide low friction in order to reduce energy losses and the environmental impact. A triboactive coating not only provides this desired performance, it also actively maintains the low friction by a structural or chemical change in a very thin top layer of these already micrometer thin coatings. This so-called tribofilm is often 5-50 nm thick and can be formed either from the coating itself or by a reaction with the counter surface or the surrounding atmosphere, i.e. gas, fuel, oil, etc. The tribofilm will maintain the wanted performance for as long as the system is not chemically disturbed. This thesis provides a detailed overview of the functionality of triboactive low-friction coatings, in many different systems. The majority of the tribofilms discussed, formed in very different environments, are built up by tungsten disulfide (WS2), which is a material similar to graphite, with a lamellar structure where strongly bonded atomic planes may slip over each other almost without resistance. The major difference is that WS2 is an intrinsically triboactive material, while graphite is not. However, graphite and other carbon-based materials can be made triboactive in certain atmospheres or by addition of other elements, such as hydrogen. The remarkable affinity and driving force to form such WS2 low-friction tribofilms, regardless of the initial states of the sulfur and tungsten, and even when the forming elements are present only at ppm levels, is a recurrent observation in the thesis. Addition of an alloying element to sputtered coatings of WS2 can improve its mechanical and frictional properties significantly. Several promising attempts have been made to find good candidates, out of which a few important ones are investigated in this thesis. Their achievable potential in friction reductions is demonstrated. By reducing friction, energy losses can be avoided, which also results in lower particle and exhaust emissions, which directly reduces the environmental impact. Triboactive coatings are shown to be a promising route to significantly improve tribological applications and allow more environmental friendly and energy efficient vehicles.

Surface temperature and heat flux measurements were made in a single cylinder SI engine piston when uncoated and with two different surface coatings: a metal TBC and YSZ. A new thermocouple was developed to accurately measure surface temperatures. The engine was operated in a standard full load mode and a knock promoting mode featuring heated intake air and advanced spark timing. Cylinder pressures were measured to quantify knock. It was found that average heat flux into the piston substrate was 33 % higher with the metal TBC and unchanged with the YSZ relative to the uncoated surface. The increase with the metal TBC was attributed to its surface roughness. However, the metal TBC and YSZ reduced peak heat flux by 69 and 77 %, respectively. Both the metal TBC and YSZ reduced knock compared to the uncoated surface. After testing, the metal TBC was undamaged and the YSZ was slightly chipped.