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Improvement Of The Mechanical Properties Of The Reaction Bonded Boron Carbide Composites By Using Multimodal Boron Carbide Powder Mixtures
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Book Synopsis Improvement of the Mechanical Properties of the Reaction Bonded Boron Carbide Composites by Using Multimodal Boron Carbide Powder Mixtures by : Amir Weizman
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:
Book Synopsis Heat Treatment of Reaction Bonded Boron-carbide Composites Fabricated at Temperatures Lower Than 1000°C by : Tal Ellert
Download or read book Heat Treatment of Reaction Bonded Boron-carbide Composites Fabricated at Temperatures Lower Than 1000°C written by Tal Ellert and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In present study, two goals were set. First, to study the effect of the initial (i.e. the preinfiltration) parameters of the preforms before infiltration on the mechanical properties. The research was focused on understanding the effect of boron carbide particle size and green density of the preforms on mechanical properties. For the first time these major parameters were decupled, and the effect of each parameter was analyzed. The second goal is to investigate the effect of post infiltrating thermal treatment on mechanical properties of reaction bonded boron carbide (RBBC). This is possible due to B4C a prolonged interaction between boron carbide and infiltrating metal, which lead to the formation of additional ceramic phases, decreasing the fraction of the residual metal and so to improve mechanical properties.
Book Synopsis The Inter-relationships Between the Static and Dynamic Mechanical Properties and the Microstructure of Reaction Bonded Boron Carbide Composites by : Shmuel Hayun
Download or read book The Inter-relationships Between the Static and Dynamic Mechanical Properties and the Microstructure of Reaction Bonded Boron Carbide Composites written by Shmuel Hayun and published by . This book was released on 2009 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fabrication Development of Boron Carbide and Boron Carbide+silicon Carbide Mixtures for Possible Application as Lumped Burnable Poisons in PWR-2 by : S. F. Kaufman
Download or read book Fabrication Development of Boron Carbide and Boron Carbide+silicon Carbide Mixtures for Possible Application as Lumped Burnable Poisons in PWR-2 written by S. F. Kaufman and published by . This book was released on 1964 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mechanical Properties of Particulate-reinforced Boron Carbide Composites by : Lorenzo W. Hankla
Download or read book Mechanical Properties of Particulate-reinforced Boron Carbide Composites written by Lorenzo W. Hankla and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The mechanical properties of boron carbide 4C) with 10 and 20 vol% particulate inclusions of commercially available nano-sized alpha-phase silicon carbide (�ł-SiC) or micron-sized titanium diboride (TiB2) were investigated so as to produce a fine-grained material with high hardness, toughness, and overall strength in order to increase the effectiveness of B4C as a structural ceramic, whose use in the field has been limited because of the extreme brittle nature of the material. Full density sintering of the ceramics (+ [or] -99% theoretical) was completed using the novel Plasma Pressure Compaction (P2C℗ʼ) technique, which limited grain growth due to a reduced processing temperature and a significantly reduced consolidation time. The reinforced ceramic composites had particulate grains homogeneously distributed within the B4C matrix. X-ray diffraction patterns confirmed that the constituents did not interdiffuse. The four-point flexure strength for the monolithic B4C ceramic was found to be significantly larger than any recorded value found in scientific literature, and was most likely attributed to the fine-grained microstructure resulting from the P2C℗ʼ processing. The mechanical properties of the nano-sized �ł-SiC-B4C ceramics showed a slight increase in the Chevron-notched four-point bend fracture toughness due to the crack deflection toughening mechanism. A slight decrease in the Vickers microhardness and the static elastic modulus values were also observed. A significant increase in the fracture toughness as well as a slight increase in the microhardness and elastic modulus of the micron-sized TiB2-B4C materials was found. The toughening mechanism of this composite was attributed to the slight chemical bond between the B4C matrix and the ultra-small, ultra-tough TiB2 particulates, which forced a propagating crack to completely rip apart the TiB2 reinforcing particles. This cleaving nature resulted in significant amounts of energy being absorbed by the micron-sized particulates. It was concluded that the composite with 20 vol% TiB2 allowed for the largest gain in toughness because it possessed the largest number of ultra small, ultra tough particulate-cracktip interactions.
Book Synopsis Mechanical Properties of Boron Carbide Particle Reinforced Aluminum Matrix Composites by : Emre Can Yürüker
Download or read book Mechanical Properties of Boron Carbide Particle Reinforced Aluminum Matrix Composites written by Emre Can Yürüker and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Chemical and Structural Characterization of Boron Carbide Powders and Ceramics by : Kanak Anant Kuwelkar
Download or read book Chemical and Structural Characterization of Boron Carbide Powders and Ceramics written by Kanak Anant Kuwelkar and published by . This book was released on 2016 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron carbide is the material of choice for lightweight armor applications due to its extreme hardness, high Young's modulus and low specific weight. The homogeneity range in boron carbide extends from ~9 to ~20 at% carbon with the solubility limits not uniquely defined in literature. Over the homogeneity range, the exact lattice positions of boron and carbon atoms have not been unambiguously established, and this topic has been the consideration of significant debate over the last 60 years. The atomic configuration and positions of the boron and carbon atoms play a key role in the crystal structure of the boron carbide phases. Depending on the atomic structure, boron carbide exhibits different mechanical properties which may alter its ballistic performance under extreme dynamic conditions. This work focusses on refinement and development of analytical and chemical methods for an accurate determination of the boron carbide stoichiometry. These methods were then utilized to link structural changes of boron carbide across the solubility range to variations in mechanical properties. After an extensive assessment of the currently employed characterization techniques, it was discerned that the largest source of uncertainty in the determination of the boron carbide stoichiometry was found to arise from the method utilized to evaluate the free carbon concentration. To this end, a modified spiking technique was introduced for free carbon determination where curve fitting techniques were employed to model the asymmetry of the 002 free carbon diffraction peak based on the amorphous, disordered and graphitic nature of carbon. A relationship was then established between the relative intensities of the carbon and boron carbide peaks to the percentage of added carbon and the free-carbon content was obtained by extrapolation. Samples with varying chemistry and high purity were synthesized across the solubility range by hot pressing mixtures of amorphous boron and boron carbide. Vibrational mode frequencies and lattice parameter measurements from Rietveld refinement were correlated to the respective B:C ratios calculated using the developed characterization techniques. An expansion of the unit cell and change in slope in the lattice parameter-stoichiometry relationship were observed at more boron rich stoichiometries. These observations were justified through the proposal of a simplified structural model considering preferential substitution of boron atoms for carbon atoms in the icosahedra from 20 at% to 13.3 at% carbon, followed by formation of B-B bonds from 13.3 at % C to ~9 at% C. Hardness measurements uncovered decreased hardness values in boron rich boron carbide which was attributed to the formation of weaker unit cells. Load induced amorphization was also detected in all the indented materials. Finally, experimental observations have shown that failure in boron carbide may be governed by a mechanism other than amorphization and synthesizing boron carbide with a modified microstructure at stoichiometries close to B4C may be the way forward to attain improved ballistic performance.
Book Synopsis Boron Carbide by : Kolan Madhav Reddy
Download or read book Boron Carbide written by Kolan Madhav Reddy and published by . This book was released on 2020-04-04 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron carbide is a superhard and lightweight ceramic material. As a result of these characteristics, it used as a protective component in bulletproof vests, tank armour and also has many other industrial applications (eg: tooling, abrasives). Research on boron carbide remains active given a long-standing challenge to understand its complex failure behavior in extreme environments owing to its unique microstructure and mechanical properties, where many current efforts are underway to improve its behavior through microstructure alteration via additives that form secondary phases, chemical doping, and altering the chemical composition of the boron-to-carbon ratio in the crystal structure. This book covers some of the key challenges involving boron carbide that are currently being studied by many materials scientists and ceramists. The authors who are active in this research field have prepared the chapters for this book and specific topics covered highlight the state-of-the art research in structure, processing, properties and applications. The organization of the book is designed to provide an easy understanding for students and professionals interested in advanced material for novel applications.
Book Synopsis Boron and Refractory Borides by : G.V. Samsonov
Download or read book Boron and Refractory Borides written by G.V. Samsonov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt: V. I. MATKOVICH During the meeting of the International Symposium on Boron held in October, 1972 in Tbilisi, U.S.S.R., the idea was proposed to assemble a review of boron and refractory borides by the specialists present. The advantages of such a work were immediately apparent. Such diverse applications of borides as in protective armor, nuclear reactors, coat ings, reinforcement, etc. can hardly all be presented in sufficient detail by a single author. On the other hand it was also recognized that with so much specialization, some areas of interest may not be covered. Within the last decade or two a number of areas have been developed in which the use of refractory borides is growing and improvements are being actively explored. Thus, a number of borides have considerable potential as reinforcing material for plastics or light metals, though only boron fibers have been firmly established up to the present. Ap plication of flakes and films for two-dimensional reinforcement appears attractive, although the high cost of materials and development repre sents a considerable barrier. A number of borides have been used to manufacture lightweight protec tive armor. In this area relatively fast changes seem to be taking place as improvements in performance and weight are made. Boron carbide has found considerable use in this application and new developments exploit the light weight of beryllium borides.
Book Synopsis Densification of Rapid Carbothermal Synthesized and Commercial Boron Carbide by Spark Plasma Sintering by : Muhammet Fatih Toksoy
Download or read book Densification of Rapid Carbothermal Synthesized and Commercial Boron Carbide by Spark Plasma Sintering written by Muhammet Fatih Toksoy and published by . This book was released on 2014 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron carbide is a structural ceramic material with exceptionally good physical and chemical properties. Thus, boron carbide is proposed for applications in extreme conditions. However synthesizing and sintering of boron carbide is extremely difficult due to its high melting point and strong covalent bonding. Secondary phases, non-uniform composition, complex stoichiometry and powder morphology are problems in most commercial powders as a result of synthesis and powder preparation procedures. Achieving more than 90% TD is difficult due to strong covalent bonding structure and low plasticity of boron carbide. Very high sintering temperatures that approach the melting point are needed for densification. This dissertation seeks to establish an improved understanding on Spark Plasma Sintering (SPS) behaviors of boron carbide and effects of powder properties on final products. Rapid carbothermal reduction (RCR) method was utilized to synthesize boron carbide powder. Submicron boron carbide powders with narrow particle size distribution were synthesized. Free carbon was significantly reduced and near B4C stoichiometry was achieved. Commercial boron carbide powders were also modified by processing in the RCR reactor. Free carbon was reduced to trace amounts; powder morphology and stoichiometry was modified. Commercial, synthesized and modified boron carbide powders were analyzed and characterized using X-Ray diffraction (XRD), electron microscopy, particle size analysis and chemical analyses. Synthesized boron carbide powder had smaller particle size, lower free carbon levels and increased concentration of twinning compared to commercial samples. Standard sintering procedure for boron carbide was established for SPS. Powders were sintered to different temperatures with various dwell times to analyze sintering behavior of boron carbide on SPS without any additives. Synthesized boron carbide powders reached +99% TD at lower temperature and shorter dwell times compared to commercial boron carbide samples. Highly dense materials were produced with limited grain growth. Dense samples were analyzed by XRD and electron microscopy. Knoop hardness tests were applied to dense boron carbide samples. Hardness results showed an improvement with RCR synthesized powders. Results were correlated and powder-sintering-final properties relations were established.
Book Synopsis Improvement on the Mechanical Properties of Boron Suboxide (B60) Based Composites Using Other Compounds as Second Phase by : Oluwagbenga Temidayo Johnson
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:
Book Synopsis Toughening of Boron Carbide Composites with Hierarchical Microstructuring by : Jingyao Dai
Download or read book Toughening of Boron Carbide Composites with Hierarchical Microstructuring written by Jingyao Dai and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: With a unique combination of properties including high hardness, high melting point, low density, neutron absorption capability, and semi-conductivity, boron carbide (B4C) is suitable for various structural and multi-functional applications. However, B4C's current applications are limited by its intrinsic brittleness. Previous studies on toughening B4C focused on mechanisms including crack deflection and micro-crack toughening by introducing secondary reinforcement such as titanium diboride (TiB2), zirconium diboride (ZrB2) and crack deflection/bridging by carbon-based nanofillers including carbon nanotubes and graphene nanoplatelets. More recent studies demonstrated novel toughening strategies including grain boundary sliding and nano-pore compression enabled by nanocrystalline, nano-porous B4C. This study pursued toughness enhancement of B4C composites through hierarchical microstructure designs that combine multiple microstructure features including TiB2 particles, graphite platelets, and nanocrystalline, nano-porous B4C phases. Using field assisted sintering technology (FAST) and starting powders of different compositions and particle sizes, three types of B4C composites were fabricated: micro/nano B4C with graphite platelets, micro B4C-TiB2 with in-situ formed micron-sized TiB2 particles, and micro/nano B4C-TiB2 with sub-micron sized TiB2 particles and graphite platelets. Hardness and fracture toughness of these B4C composites were characterized using indentation at micro scale and using four-point bending at macro scale. Fracture toughness enhancement was observed for fabricated B4C composites: 2.38 MPa∙m1/2 for the reference B4C sample, 2.85 MPa∙m1/2 for the micro/nano B4C with ~10 vol% graphite platelets, 3.32 MPa∙m1/2 for the micro B4C-TiB2 with ~15 vol% TiB¬2, and 3.65 MPa∙m1/2 for the micro/nano B4C-TiB2 with ~15 vol% TiB2 and ~8.7 vol% graphite platelets when measured by the four-point bending. The fabricated micro/nano B4C-TiB2 samples exhibited high fracture toughness while retaining high hardness (31.88 GPa with ~15 vol% TiB2) due to inhibited grain growth, despite the lower hardness of formed graphite platelets and TiB2 particles. Through post-testing microstructure inspection, toughening mechanisms for the fabricated B4C composites were identified as graphite delamination, crack deflection, bridging, and micro-crack toughening. To obtain more understanding about the toughening contribution from each mechanism, micromechanics modeling was conducted for the micro and micro/nano B4C-TiB2 composites which exhibited the highest fracture toughness enhancement. The thermal residual stress resulted from the coefficient of thermal expansion mismatch between B4C and TiB2, and the existence of weak interphases were found to be two main driving factors behind the observed micro-crack toughening behavior. This thesis work demonstrated fracture toughness enhancement, without degradation of hardness, can be achieved through multiple toughening mechanisms enabled by the hierarchical microstructure design with components including TiB2 grains, graphite platelets, etc. The basic process-microstructure-property relations established in this study for B4C composites with hierarchical microstructures will contribute to future microstructure designs of ceramic composites with enhanced fracture toughness.
Book Synopsis Mechanical Properties of Boron Carbide (B4C) by : Ruslan Kuliiev
Download or read book Mechanical Properties of Boron Carbide (B4C) written by Ruslan Kuliiev and published by . This book was released on 2020 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron carbide (B4C) is one of the most important opaque boride ceramics that has high hardness and Young’s modulus that along with low density lead to a significant resistance to ballistic impact and, thus, B4C is broadly used as a protective material. B4C has also high neutron capturing cross section; therefore, it is used as control rods and neutron absorption shielding in nuclear reactors. In this work thermal, electrical and mechanical properties of dense B4C ceramics (99%) sintered using Spark Plasma Sintering (SPS) were investigated. The Young’s modulus of B4C measured by three different techniques -- IE, RUS, and nanoindentation showed a very good overlap in values, which ranges from 419.2 ± 47.3 GPa for nanoindentation to 458.7 GPa for RUS measurements at room temperature. The mean contact pressure-contact depth plots obtained from load-displacement nanoindentation data indicated pop-in events during loading and an “elbow” event during unloading, both of which are indicative of possible structural changes in B4C structure during nanoindentation. The appearance of “elbow” deviations in load-displacement nanoindentation curves of B4C was detected for the first time. The 4-point bending strength of the B4C ceramics was equal to 585±70 MPa with Weibull parameter of 9.9 and scale parameter equal to 611 MPa. The biaxial strength of B4C was measured to be much lower and equal to 238.6±122 MPa with Weibull parameters of 2.2 and scale parameter equal to 271 MPa. To the best of our knowledge the biaxial strength of B4C was also measured for the first time. In this work it was determined that failure of B4C occurred by fully transgranular fracture, with no intergranular failure present on fracture surface. B4C’s fracture toughness K[subscript lc] = 3±0.19 MPa x m[superscript 1/2] was measured using SEVNB technique, which is similar to previously reported values.
Book Synopsis Determination of Structural Changes and Phase Transformations in Boron Carbide by Static and Dynamic Studies by : Varun Gupta
Download or read book Determination of Structural Changes and Phase Transformations in Boron Carbide by Static and Dynamic Studies written by Varun Gupta and published by . This book was released on 2010 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent transmission electron microscopy results demonstrate that the failure of B4C is commensurate with the segregation of boron icosahedra embedded in amorphous carbon in 2-3 nm wide amorphous bands along the (113) lattice direction, in good agreement with our recent theoretical results. Boron carbide is generally composed of multiple polytypes of B4C which have the same primitive lattice parameters but differ from each other by the location of the boron and carbon atoms in the unit cells. The unit cells are formed by a 12-atom B12-nCn icosahedron and a 3-atom (C3-nBn) chain. Our theoretical results indicate that one polytype, B12(C3), whose formation is responsible for the failure of the entire material. This anomalous and poorly understood glass-like behavior in boron carbide has been the subject of research since its discovery over 70 years ago. The characterization of disorder in hot pressed and powder boron carbide samples is therefore of primary interest. The research work has focused on characterization techniques which can be used at a micrometric sampling size so that individual powder grains of the material can be utilized. Specifically, micro-Raman and electrical conductivity measurements can be used with micrometric gap cells to understand the disorder in B4C. The results also demonstrate that it is possible to induce transformations in boron carbide using electric fields that are comparable with those obtained under shock and nanoindentation. Our calculations present a hypothesis which can provide a solution to prevent the premature failure of B4C. A route to achieve suppression of the B12(CCC) polytype without significantly affecting the elastic constants is via low concentration Silicon (Si) doping of B4C. Suppression of B12(CCC) by Si doping has implications towards development of boron carbide armor with improved properties for protection against high velocity threats. In order to achieve this, nanostructures (nanowires, nanorods, etc.) of Sidoped boron carbide have been synthesized using a Solid-Liquid-Solid (SLS) growth mechanism. The resulting structures have been characterized by SEM, TEM and Raman spectroscopy and consolidated to evaluate their mechanical properties. In addition, the application of nanowires in a transparent and thermally conducting nanocomposite is demonstrated.
Book Synopsis Boron Carbide/magnesium Alloys Composites by : Matan Cafri
Download or read book Boron Carbide/magnesium Alloys Composites written by Matan Cafri and published by . This book was released on 2012 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Improved Method for the Preparation of Boron Carbide with Some Notes on Its Properties by : Henry James Wheeler Bliss
Download or read book An Improved Method for the Preparation of Boron Carbide with Some Notes on Its Properties written by Henry James Wheeler Bliss and published by . This book was released on 1905 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Mechanical Response of Boron Carbide-aluminum Composites During Compressive Loading by :
Download or read book The Mechanical Response of Boron Carbide-aluminum Composites During Compressive Loading written by and published by . This book was released on 2000 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
