Mechanical Properties Of Boron Carbide B4c
DOWNLOAD
Download Mechanical Properties Of Boron Carbide B4c PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Mechanical Properties Of Boron Carbide B4c book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Mechanical Properties Of Boron Carbide B4c
DOWNLOAD
Author : Ruslan Kuliiev
language : en
Publisher:
Release Date : 2020
Mechanical Properties Of Boron Carbide B4c written by Ruslan Kuliiev and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
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.
Mechanical Properties Of Particulate Reinforced Boron Carbide Composites
DOWNLOAD
Author : Lorenzo W. Hankla
language : en
Publisher:
Release Date : 2008
Mechanical Properties Of Particulate Reinforced Boron Carbide Composites written by Lorenzo W. Hankla and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
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.
Mechanical Properties Of Pecvd Boron Carbide
DOWNLOAD
Author : Dhairyashil U. Aher
language : en
Publisher:
Release Date : 2011
Mechanical Properties Of Pecvd Boron Carbide written by Dhairyashil U. Aher and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Determination Of Structural Changes And Phase Transformations In Boron Carbide By Static And Dynamic Studies
DOWNLOAD
Author : Varun Gupta
language : en
Publisher:
Release Date : 2010
Determination Of Structural Changes And Phase Transformations In Boron Carbide By Static And Dynamic Studies written by Varun Gupta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Boron compounds categories.
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.
Boron Carbide
DOWNLOAD
Author : Kolan Madhav Reddy
language : en
Publisher:
Release Date : 2020-04-04
Boron Carbide written by Kolan Madhav Reddy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-04-04 with categories.
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.
Chemical And Structural Characterization Of Boron Carbide Powders And Ceramics
DOWNLOAD
Author : Kanak Anant Kuwelkar
language : en
Publisher:
Release Date : 2016
Chemical And Structural Characterization Of Boron Carbide Powders And Ceramics written by Kanak Anant Kuwelkar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Boron categories.
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.
Improvement Of The Mechanical Properties Of The Reaction Bonded Boron Carbide Composites By Using Multimodal Boron Carbide Powder Mixtures
DOWNLOAD
Author : Amir Weizman
language : en
Publisher:
Release Date : 2009
Improvement Of The Mechanical Properties Of The Reaction Bonded Boron Carbide Composites By Using Multimodal Boron Carbide Powder Mixtures written by Amir Weizman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Boron compounds categories.
Heat Treatment Of Reaction Bonded Boron Carbide Composites Fabricated At Temperatures Lower Than 1000 C
DOWNLOAD
Author : Tal Ellert
language : en
Publisher:
Release Date : 2020
Heat Treatment Of Reaction Bonded Boron Carbide Composites Fabricated At Temperatures Lower Than 1000 C written by Tal Ellert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
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.
Computational Studies Of Physical Properties Of Boron Carbide
DOWNLOAD
Author :
language : en
Publisher:
Release Date : 2011
Computational Studies Of Physical Properties Of Boron Carbide written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
The overall goal is to provide valuable insight in to the mechanisms and processes that could lead to better engineering the widely used boron carbide which could play an important role in current plight towards greener energy. Carbon distribution in boron carbide, which has been difficult to retrieve from experimental methods, is critical to our understanding of its structure-properties relation. For modeling disorders in boron carbide, we implemented a first principles method based on supercell approach within our G(P, T) package. The supercell approach was applied to boron carbide to determine its carbon distribution. Our results reveal that carbon prefers to occupy the end sites of the 3-atom chain in boron carbide and further carbon atoms will distribute mainly on the equatorial sites with a small percentage on the 3-atom chains and the apex sites. Supercell approach was also applied to study mechanical properties of boron carbide under uniaxial load. We found that uniaxial load can lead to amorphization. Other physical properties of boron carbide were calculated using the G(P, T) package.
The Effect Of Boron Carbide Addition On The Structural And Mechanical Properties Of Tungsten Matrix Composites
DOWNLOAD
Author : Nil Ünal
language : en
Publisher:
Release Date : 2006
The Effect Of Boron Carbide Addition On The Structural And Mechanical Properties Of Tungsten Matrix Composites written by Nil Ünal and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.