Microstructural characterization of boron-rich boron carbide

Xie, Kelvin Y.; Domnich, Vladislav; Farbaniec, Lukasz; Chen, Bin; Kuwelkar, Kanak; Ma, Luoning; McCauley, James W.; Haber, Richard A.; Ramesh, K.T.; Chen, Mingwei; Hemker, Kevin J.

doi:10.1016/j.actamat.2017.06.063

Cited by 97 publications

(74 citation statements)

References 53 publications

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“…As shown in Figure A, porosity plus two secondary phases was observed in ZB, neither of which was detected by XRD. These secondary phases were determined to be graphitic carbon (black high aspect ratio particles) and B 4 C (dark gray equiaxed grains) using Raman spectroscopy . The graphitic carbon was present in trace amounts, and the B 4 C content was estimated to be ~1.0 vol% based on areal analysis of the micrographs.…”

Section: Resultsmentioning

confidence: 99%

“…These secondary phases were determined to be graphitic carbon (black high aspect ratio particles) and B 4 C (dark gray equiaxed grains) using Raman spectroscopy. 41,42 The graphitic carbon was present in trace amounts, and the B 4 C content was estimated to be ~1.0 vol% based on areal analysis of the micrographs. Graphitic carbon was found to be isolated to the grain boundaries of the ZB structure.…”

Section: F I G U R E 1 Xrd Patterns Of Zb and Ztb With The Inset Plotmentioning

confidence: 99%

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Solute distributions in tantalum‐containing zirconium diboride ceramics

et al. 2019

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Solute segregation was examined in zirconium diboride and zirconium‐tantalum diboride solid solution ceramics that were produced by reactive hot pressing. Microstructural analysis demonstrated that the ZrB2 and (Zr,Ta)B2 ceramics reached nearly full relative density and were nominally phase‐pure. X‐ray diffraction was consistent with full incorporation of Ta into solid solution within the ZrB2 structure, and energy‐dispersive spectroscopy demonstrated that tantalum was well distributed throughout the bulk of the Ta‐doped specimens. The weak characteristic X‐rays for B led to inaccurate results for total atom concentrations in boride ceramics by energy‐dispersive spectroscopy. Atom probe tomography was used to analyze the amount and spatial distribution of Ta species. No obvious Ta segregation was observed in grains or grain boundaries. However, nitrogen strongly segregated to a grain boundary. This study demonstrated that atom probe tomography is an accurate method for characterizing the amount and spatial distribution of metallic and nonmetallic species in ZrB2 ceramics.

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Section: Resultsmentioning

confidence: 99%

Section: F I G U R E 1 Xrd Patterns Of Zb and Ztb With The Inset Plotmentioning

confidence: 99%

Solute distributions in tantalum‐containing zirconium diboride ceramics

et al. 2019

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“…An X-ray diffraction pattern taken from polished surface of B 4 C is shown in Figure 2A. All of the diffraction peaks in the pattern belong to the rhombohedral Bravais lattice of space group of B 4 C and the peak at~26.16 • 2θ belonging to carbon indicates that a small quantity of carbon was present as a secondary phase [8,91]. Raman spectrum obtained using a 532 nm laser measured from a polished surface of B 4 C is shown in Figure 2B.…”

Section: Shrinkage Behavior Structure Thermal Expansion and Electrimentioning

confidence: 99%

“…13, 1612 7 of 21 Reference[91,92]. The grain size of B 4 C was equal to 3.4 ± 0.05 micron as estimated from the fracture surface of broken samples(Figure 3).Materials 2020, 13, x FOR PEER REVIEW 7 of (A) X-ray diffraction pattern and (B) Raman spectrum of B4C taken from polished surface.…”

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confidence: 99%

Spark Plasma Sintered B4C—Structural, Thermal, Electrical and Mechanical Properties

et al. 2020

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The structural, thermal, electrical and mechanical properties of fully dense B 4 C ceramics, sintered using Spark Plasma Sintering (SPS), were studied and compared to the properties of B 4 C ceramics previously published in the literature. New results on B 4 C's mechanical responses were obtained by nanoindentation and ring-on-ring biaxial strength testing. The findings contribute to a more complete knowledge of the properties of B 4 C ceramics, an important material in many industrial applications.Materials 2020, 13, 1612 2 of 21 bonds, the intericosahedral bonds and the highly delocalized intraicosahedral sp2 bonds [5]; and their localization and delocalization, iconicity and covalent character along with the electron density determine the properties of B 4 C [15][16][17][18][19]. Group theory predicts 5A 1g + 2A 1u + 2A 2g + 6A 2u + 7E g + 8E u representation for the normal modes of lattice dynamics of R3m rhombohedral B 4 C, where the 12 modes of A 1g and Eg symmetry are Raman active, the 14 modes of A 2u and E u symmetry are Infrared (IR) active and the A 1u and the A 2g modes are optically inactive. When the zero-frequency modes are removed, the number of IR active modes become 12 [20]. If carbon atoms are introduced into the icosahedron, a higher number of vibrational modes can be expected in the collected spectra [5].It was reported that B 4 C exhibits a strong anisotropy of the elastic constants, meaning that elastic moduli are orientation dependent [21]. It was found that the Young's modulus of B 5.6 C single crystal has a maximum E max = 522 GPa along the [111] direction and a minimum Emin = 64 GPa and a maximum shear modulus Gmax = 233 GPa along the [201] direction and Gmin = 165 GPa in the [112] direction [5]. The elastic moduli of isotropic polycrystalline B 4 C have a dependence on the stoichiometry of the B or C atoms [22][23][24][25][26]. While B 4 C exhibits high elastic moduli, determined by the atomic bonding in the compound, the extremely rigid framework arising from the covalently bonded icosahedra and chain units leads to their refractory nature and extreme hardness [27]. B 4 C shows good flexure strength, which is dependent on external factors, such as processing conditions, size of the samples tested, grain size, porosity, presence of defects and so forth. Because B 4 C ceramic is relatively brittle, it shows a strong flaw sensitivity, where defects play a detrimental role and often are responsible for premature failure. Therefore, there has been a significant effort to improve the compaction technologies to provide enhancement in sintering, with the majority of the techniques used for densification of B 4 C being pressureless sintering [28][29][30][31][32], hot pressing [33][34][35][36], hot isostatic pressing [37], direct current sintering [38][39][40][41][42], high pressure sintering in multi-anvil apparatus [43] and contactless flash sintering [44] techniques. Currently, the most accepted and well developed processing technique for densification of B 4 C is the direct current sinterin...

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“…B 4 C consists of 12‐atom icosahedra (mostly B 11 C) connected via 3‐atom linear chains (eg, ‐CBC‐). Subhash et al suggested that doping Si, Ni and B into boron carbide could prevent the icosahedra from collapsing, thus mitigating amorphization in boron carbide. An et al performed density functional theory calculations and proposed that replacing ‐CBC‐ chain with Si–Si chain (Si‐doping) would stabilize the icosahedra, so that the system could shear without breaking the icosahedra and alleviating amorphization .…”

Section: Introductionmentioning

confidence: 99%

The effect of boron and aluminum additions on the microstructure of arc‐melted boron carbide

et al. 2020

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In this work, B4C, B4C + 5 at.% Al, B4C + B, and B4C + B + 5 at.% Al were arc melted, and the resultant solid products were characterized. Results from x‐ray diffraction and scanning electron microscopy showed that adding Al alone in B4C did not result in Al doping; adding Al and B in B4C led to Al doping. Al‐doping also changed the surface energy of boron carbide in the liquid state, thus altered the wettability. Transmission electron microscopy revealed that stacking faults are more likely to form in the Al‐doped sample, especially in the regions where the Al concentration is high.

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Microstructural characterization of boron-rich boron carbide

Cited by 97 publications

References 53 publications

Solute distributions in tantalum‐containing zirconium diboride ceramics

Solute distributions in tantalum‐containing zirconium diboride ceramics

Spark Plasma Sintered B4C—Structural, Thermal, Electrical and Mechanical Properties

The effect of boron and aluminum additions on the microstructure of arc‐melted boron carbide

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