A diffusion approach for plasma synthesis of superhard tantalum borides

Rau, Aaditya; Chakrabarty, Kallol; Gullion, William; Baker, Paul; Bikmukhametov, Ilias; Martens, R. L.; Thompson, Gregory B.; Catledge, Shane A.

doi:10.1557/jmr.2019.357

Cited by 3 publications

(2 citation statements)

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“…Reactant gases for the growth of the boron carbide coatings include H 2 and B 2 H 6 , but little is known of the plasma species and underlying the spectroscopic aspects responsible for boron carbide growth in its various structural forms. Investigation of the excited state plasma species from optical emission spectroscopy in our MPCVD system shows that emission from atomic boron is highest at low chamber pressure and high microwave power [ 25 , 26 ]. Copious amounts of atomic boron in the plasma may be beneficial under some growth conditions for producing high hardness boron-rich carbides, such as B 50 C 2 , B 50 C, B 48 C 3 , B 51 C, B 49 C 3 , or many other forms of boron-rich carbide.…”

Section: Introductionmentioning

confidence: 99%

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

et al. 2020

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Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness.

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Section: Introductionmentioning

confidence: 99%

Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

et al. 2020

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“…With recent efforts in developing liquid lithium and tungsten PFCs (such as the wall materials projected for use in ITER), the simulation framework developed in this study can provide a starting point for understanding bombardment processes in those systems. Furthermore, plasma deposition of boron has been used to create hard coatings for metals, thus the current work has potential for improving understanding of surface modification with boron even beyond fusion device development [29][30][31].…”

Section: Discussionmentioning

confidence: 99%

Simulations of graphite boronization: A molecular dynamics study of amorphization resulting from bombardment

et al. 2022

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The molecular dynamics code LAMMPS was used to simulate the bombardment of a graphite structure by atomic boron with impact energies ranging from 50–250 eV. The transient structural evolution, penetration depth, and amorphous layer thickness were analyzed. Simulations show that larger impact energies lead to a greater volume of amorphization and penetration of boron, but that the growth rate of the amorphous layer decreases with increasing fluence. Furthermore, the change in surface chemistry of the amorphized structures was studied using the ReaxFF formalism, which found that the amorphization process introduces dangling bonds thus increasing reactivity in the amorphous region.

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