Thesis (M.S.)--University of Wisconsin--Madison, 1953. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 40).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 91-95).

An absorption complex or compound between boron nitride and chromyl chloride was discovered and studied in some detail. The method used to prepare the boron nitride had some effect on the composition of the complex but for a given sample of boron nitride the equilibrium composition for temperatures from 0°C to 160°C was constant. The kinetics of formation were studied at 24.1°C, 67.1°C, and 117.0°C. The reaction was interpreted as diffusion controlled with two diffusion coefficients--each for a certain concentration range. The corresponding two energies of activation were 5.0 and 6.1 kcal. These are of the same order of magnitude as for similar processes. X-ray studies of the complex showed a strong reflection line at the same place as for the main layer separation in boron nitride itself. There could have been a small amount of reflection due to a greater layer spacing, but it was not detected. Water hydrolyses the chromyl chloride in the complex, leaving the original boron nitride and a solution of dichromate and HCl. Carbon tetrachloride would not dissolve out the chromyl chloride from the complex. Similar complexes of chromyl chloride with disulfides of molybdenum, tungsten and uranium and of cupric and aluminum chlorides with boron nitride were discovered but the kinetics of their formation were not studied. The theory of formation of lamellar compounds is discussed. / Science, Faculty of / Chemistry, Department of / Graduate

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Ph.D., Faculty of Engineering and the Built Environment, University of the Witwatersand, 2012 / This thesis focuses on the boron suboxide B6O, a boron-rich super-hard ceramic material. With hardness values previously reported between 24 GPa and 45 GPa, B6O is one of the hardest known materials. Although first reports on boron suboxides date back as far as 1909 (Weintraub E., Transactions of the American Electrochemical Society, 16 (1909) 165), it is the B6O-based composites that have attracted considerable interest in recent years due to their enormous technological potential, especially as an alternative to polycrystalline diamond and polycrystalline cubic boron nitride for wear and abrasive applications. Investigations into the properties of B6O itself appear to have been neglected in favour of the improvement of densification and fracture toughness of the composites. The B6O samples used for the work reported in this work was hot-pressed was prepared under an argon environment at 1800 C and 50 MPa for 20 minutes followed metallographical preparation. The density of the hot-pressed compacts measured 2.44 g/cm3. The starting B6O powder material was supplied from the Fraunhofer Institute for Ceramic Technologies and Systems, Dresden. This thesis primarily seeks to generate and report as much practical data for polycrystalline B6O materials prepared by uniaxial hot-pressing as possible from a variety of characterization techniques. Firstly, the Raman spectra of hot-pressed B6O, which was until now poorly understood, was investigated using using a 514.5 nm green Ar+ laser excitation source. Secondly, the fundamental nature of some mechanical properties of hot-pressed B6O were investigated by means of Vickers and Berkovich indentation techniques. New approaches for data analysis, especially the investigations of the nanomechanical properties of hot-pressed B6O by Berkovich nanoindentation, were also suggested. Thirdly, the intrinsic hardness of hot-pressed B6O was investigated by means of a comprehensive inter-model comparison study. Fourthly, a combined experimental and simulation approach for determining mechanical properties of hot-pressed B6O by nanoindentation was also carried out, based on the outcomes of the study, the deformation response of the material under dynamic indentation was investigated at di erent stages using a custom developed finite element model. Finally, based on the preliminary ab initio density functional calculations of the structural properties of B6O conducted by Lowther showing that the presence of a high electronegativity interstitial in the B6O structure could enhance the strength of the bonding in B6O, fluorine ion implantation into B6O were conducted. The e ects to the structural and the nanomechanical properties of radiation damage induced by ion implantation was investigated. The possible formation of novel nanostructures in the ion-irradiated B6O matrix near-surface was also investigated. Results obtained from this study provides a vast amount of practical data for hot-pressed B6O materials as well as a number of novel analysis approaches for the extraction useful properties from the measured raw data. Firstly, using an automated background subtraction method, observable first- and second-order Raman spectra of B6O were obtained. A comparative analysis with previously reported spectra of other -rhombohedral boron-rich ceramic materials demonstrate a good agreement. Results also confirm the existence of highly resolved Raman modes measured at ambient conditions using a green Ar+ excitation source which is contrary to the conventional understanding. Secondly, results from the micro-indentation investigations indicate the measured microhardness exhibits indentation load dependence. A model inter-comparison study of indentation size e ects in the microhardness measurements of hot-pressed B6O is comprehensively discussed. Thirdly, the intrinsic hardness value of 30 GPa was deduced. Fourthly, a quantitative analysis approach was developed to simulate multi-cycling loading load-displacement curves from a single measured load-displacement nanoindentation curve. Based on the results, the nature of the indentation size e ect in the nanoindentation hardness as well as the intrinsic nanomechanical properties of hot-pressed B6O were established. Fifthly, a combined experimental and finite element method simulation approach for determining mechanical properties of hot-pressed B6O by nanoindentation was developed. Based on the outcomes of the combined experimental and simulation studies, the deformation response of the material under dynamic indentation was also investigated at di erent stages using a custom developed finite element model. Finally, results from the structural characterization of the ion implanted B6O material demonstrates the formation of novel nanostructures by means of the ion bombardment of B6O. In addition, the study presented here also seeks to investigate the e ects of the fluorine ion implantation on the near-surface nanomechanical properties of hot-pressed B6O. The principal conclusions that the study provide are both comprehensive practical data for B6O materials prepared by uniaxial hot-pressing. A number of properties, including the Raman spectra, the intrinsic hardness, and the radiation resistance and the e ects of radiation damage are reported in the thesis.

A series of boron suboxide films with hardness higher than 40 GPa was prepared and characterized. The correlation between OB ratio and mechanical properties, both hardness and elastic modulus were analyzed. Our studies on beta r-B, B2O3, surface oxidation of betar-B, and B6O illustrate that an XPS peak shift can be caused by a change in chemical state and bonding configuration. The shifts of B 1s peaks provide some good evidence to substantiate this conventional wisdom of XPS. We have applied this concept to enrich our XPS studies of boron and BxO y, and indeed found an intriguing variety of surface and interfacial physical conditions of those samples. / In our study, three boron nitride (BN) samples, the c-BN, h-BN and a-BN were prepared to serve as the standard specimens. And also, a series of thick BN films with different cubic phase content were prepared using a dual-ion beam assisted deposition (DIBAD) system. A quantitative method to measure the various phases content in BN film by the deconvolution of the energy loss features of N 1s signal was established. The feasibility of this method was proved by comparing the results with the results from FT-IR. To our understanding, this method has never been reported. / Many mechanical applications constantly demand superhard materials. Commonly a material is qualified as "superhard" when its microhardness exceeds 40 GPa. Therefore, great efforts have been made to search for other materials with high hardness in the past several decades. In the design of superhard materials, boron is a peculiar element/constituent. c-BN that possesses the zinc-blende structure shows numerous highly desirable mechanical properties, especially the high hardness and chemical inertness. Boron often exhibits three-center two-electron bonds in addition to the common two-center two-electron bonds. This overall bonding configuration must be very effective as shown by the high hardness of solid boron at 35 GPa. When impurities with more valence electrons than boron are added to pure boron, the overall mechanical strength can be further enhanced. By incorporation of oxygen, a family of hard boron suboxide compounds is thereby formed such as B6O. / Zheng Bin. / "August 2005." / Adviser: Chan Man Chor. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6427. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Chemistry." Includes bibliographical references (p. 146-161).