Download or read book Improvement on the Mechanical Properties of Boron Suboxide B60 Based Composites Using Other Compounds as Second Phase written by Oluwagbenga Temidayo Johnson and published by . This book was released on 2008 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Improvement of the Mechanical Properties of the Reaction Bonded Boron Carbide Composites by Using Multimodal Boron Carbide Powder Mixtures written by Amir Weizman and published by . This book was released on 2009 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boron Suboxide B6O Materials with Improved Properties written by Oluwagbenga Johnson and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of low fracture toughness and the difficulties to densify has delayed the application of boron suboxide (B6O) materials as superhard materials in the industry. Therefore, in this book, efforts have been directed towards improving the fracture toughness and densification of these materials by incorporating suitable secondary phases. Possible candidates are transition metals, which form under sintering conditions a liquid phase. Therefore different Co containing additives (metal, oxide & boride) were used to densify boron suboxide powder by hot pressing. The resulting materials have a strongly improved fracture toughness (3.9 MPam1/2) and still high hardness (HV5=28.6 GPa.).
Download or read book Improving Hardness and Toughness of Boride Composites Based on AIMgB14 written by and published by . This book was released on 2007 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB14-TiB2 composite. The composite has been shown to exhibit hardness greater than either of its constituent phases, relying on its sub-micron microstructure to provide hardening and strengthening mechanisms. With possible hardness around 40 GPa, an AlMgB14 - 60 vol% TiB2 approaches the hardness of cBN, yet is amenable to processing under ambient pressure conditions. There are interesting aspects of both the AlMgB14 and TiB2 phases. AlMgB14 is comprised of a framework of boron, mostly in icosahedral arrangements. It is part of a family of 12 known compounds with the same boron lattice, with the metal atoms replaced by Li, Na, Y or a number of Lanthanides. Another peculiar trait of this family of compounds is that every one contains a certain amount of intrinsic vacancies on one or both of the metal sites. These vacancies are significant, ranging from 3 to 43% of sites depending on the composition. TiB2 is a popular specialty ceramic material due to its high hardness, moderate toughness, good corrosion resistance, and high thermal and electrical conductivity. The major drawback is the difficulty of densification of pure TiB2 ceramics. A combination of sintering aids, pressure, and temperatures of 1800 C are often required to achieve near full density articles. The AlMgB14 - TiB2 composites can achieve 99% density from hot-pressing at 1400 C. This is mostly due to the preparation of powders by a high-energy milling technique known as mechanical alloying. The resulting fine powders have high activity, and Fe from wear debris acts as a sintering aid. Mechanical alloying improves the sinterability of the composite material, it has the same effect on pure TiB2. TiB2 processed by high-energy milling has been found to achieve 99% theoretical density at 1400 C with the addition of 1̃ wt% Fe. Both the AlMgB14 - TiB2 composites and pure TiB2 produced from these methods have enhanced mechanical properties due to their fine microstructures. These materials show exceptional promise in the field of wear resistance. This includes cutting tools, erosion resistant coatings, and low-friction sliding contacts to name a few. Under certain wear conditions, the composite material can show performance on par with that of current high-end cBN and WC materials tailored for wear resistance. The composite material also exhibits low reactivity with Ti alloys, a pre-requisite for effective machining of these alloys, a trait that few hard materials possess.
Download or read book Optimization of Boride Containing Boron Suboxide B6O Materials written by Oluwagbenga Johnson and published by LAP Lambert Academic Publishing. This book was released on 2012 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for suitable additives for boron suboxide (B6O) materials which could improve densification, reduce sintering temperature and tailor the microstructure has been of great importance. B6O materials doped with 0-5 vol% cobalt addition were sintered at temperatures up to 1850oC and pressure of 50MPa for 20mins. Relationship among the formed phases, microstructures and mechanical properties of the sintered materials was investigated as a function of sintering conditions and added cobalt content. The hardness of the sintered B6O materials increases with sintering temperature, while it decreases with increase in cobalt content. The reverse is also true for the fracture toughness.
Download or read book Development of Boron Suboxide Composites with Improved Toughness written by Anthony Andrews and published by . This book was released on 2008 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Boron Rich Solids written by Nina Orlovskaya and published by Springer. This book was released on 2010-10-01 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •Boron-rich solids: science and technology •Synthesis and sintering strategies of boron rich solids •Microcantilever sensors •Screening of the possible boron-based thermoelectric conversion materials; •Ultra-high temperature ZrB2 and HfB2 based composites •Magnetic, transport and high-pressure properties of boron-rich solids •Restrictions of the sensor dimensions for chemical detection •Armor
Download or read book The Preparation and Characterization of Boron Suboxide B6O Based Composites written by Thembinkosi Collison Shabalala and published by . This book was released on 2007 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomic Layer Deposition for Semiconductors written by Cheol Seong Hwang and published by Springer Science & Business Media. This book was released on 2013-10-18 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offering thorough coverage of atomic layer deposition (ALD), this book moves from basic chemistry of ALD and modeling of processes to examine ALD in memory, logic devices and machines. Reviews history, operating principles and ALD processes for each device.
Download or read book Analysis of an Improved Boron Aluminum Composite written by JL. Christian and published by . This book was released on 1972 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improvements in the mechanical properties of a boron/aluminum composite material have been achieved through thermal treatments and the addition of small amounts of high strength stainless steel wires perpendicular to the boron. This study provides an analysis of these improved composite materials, utilizing scanning electron microscopy and X-ray radiography to examine the micromechanics of the composites and their fiber and matrix components. Phenomena analyzed and discussed are matrix-matrix bonding, filament-matrix bonding, matrix failure, filament damage, and fracture initiation and propagation.
Download or read book Novel Molecular Sources for Dispersing Boron in Carbon Carbon Composites written by and published by . This book was released on 1993 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improving the oxidation resistance of carbon-carbon composites is key to extending the applications of this material system into higher temperature regimes. While molecularly dispersed boron, through addition of carborane, helps to provide oxidation protection to phenolic derived carbon, the moisture affinity of the boria seriously affects composite performance. Substitution of furfuryl and pitch as the resin precursors significantly improved the moisture resistance of the carbon matrix material by stabilizing the boron at low temperatures and minimizing premature boria formation. Carborane addition to a commercial furfuryl/pitch blend (Kaiser Code88A) yielded a carbon char with reduced moisture affinity and improved oxidation resistance. Mechanical properties of the Code88A matrix composites were not significantly affected by the addition of carborane. Although sample size limitations in testing detracted from the demonstration of success, data suggests that the oxidation resistance of carbon-carbons can be significantly enhanced via this approach without detriment to the physical attributes and moisture resistance of the composite. (MM).
Download or read book Synthesis and Mechanical Properties of Two Phase Nanostructured Al Based Composites written by Koteswararao Venkata Rajulapati and published by . This book was released on 2006 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: high pressure torsion, ball milling, mechanical properties, second phase, transmission electron microscopy, nanocrystalline materials.
Download or read book Ceramic Abstracts written by and published by . This book was released on 1999 with total page 950 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Clean Electricity From Photovoltaics written by Mary D Archer and published by World Scientific. This book was released on 2001-06-04 with total page 870 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic cells provide clean, reversible electrical power from the sun. Made from semiconductors, they are durable, silent in operation and free of polluting emissions. In this book, experts from all sectors of the PV community — materials scientists, physicists, production engineers, economists and environmentalists — give their critical appraisals of where the technology is now and what its prospects are./a
Download or read book Molecular Modelling and Synthesis of Nanomaterials written by Ihsan Boustani and published by Springer Nature. This book was released on 2020-07-14 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents nanomaterials as predicted by computational modelling and numerical simulation tools, and confirmed by modern experimental techniques. It begins by summarizing basic theoretical methods, then giving both a theoretical and experimental treatment of how alkali metal clusters develop into nanostructures, as influenced by the cluster's "magic number" of atoms. The book continues with a discussion of atomic clusters and nanostructures, focusing primarily on boron and carbon, exploring, in detail, the one-, two-, and three-dimensional structures of boron and carbon, and describing their myriad potential applications in nanotechnology, from nanocoating and nanosensing to nanobatteries with high borophene capacity. The broad discussion of computational modelling as well as the specific applications to boron and carbon, make this book an essential reference resource for materials scientists in this field of research.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1975 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
