Preparation of Ni-precipitated hBN powder by rotary chemical vapor deposition and its consolidation by spark plasma sintering

Zhang, Jianfeng; Tu, Rong; Goto, Takashi

doi:10.1016/j.jallcom.2010.04.170

Cited by 32 publications

(15 citation statements)

References 16 publications

(21 reference statements)

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“…Relative density was observed to increase with increasing cBN content, reaching a maximum at 30 wt% cBN. The relative density of HSHBN-30 reached 95.5% at 1600 °C, slightly higher than the highest-reported result for hBN ceramics, of 95.1% in a sample sintered at 2000 °C 11 . When the sintering temperature is increased to 1700 °C, the relative density of the HSHBN-30 correspondingly increases to 97.6%.…”

Section: Resultscontrasting

confidence: 58%

“…Recently, Zhang et al 11 sintered hBN without any additives via spark plasma sintering (SPS) under an applied pressure of 100 MPa and achieved a relative density of 95.1% at a temperature of 2000 °C. While Zhang’s results are encouraging, the sintering conditions are too harsh to be feasible for the mass production of dense, high-purity dense hBN ceramics.…”

Section: Introductionmentioning

confidence: 99%

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Low temperature self-densification of high strength bulk hexagonal boron nitride

Yang

Fang

et al. 2019

Nat Commun

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Hexagonal boron nitride (hBN) ceramics are expected to have wide applications at high temperatures as both a structural and functional material. However, because of its flake structure and general inertness, it is currently impossible to sinter hBN powder to a dense bulk (with a relative density of above 96%) even at 2000 °C. Here, we report dense bulk hBN with 97.6% theoretical density achieved at a lower preparation temperature (1700 °C) via a self-densifying mechanism without sintering additives. During the sintering process, cubic boron nitride particles incorporated into the hBN flake powders transform into BN onions with a significant volume increase, thus filling in voids among the hBN flakes and highly densifying the hBN bulks. The resulting dense hBN ceramics possess 2–3 times the strength of traditional hBN ceramics. This phase-transition-induced volume expansion strategy could lead to dense sintered compacts with high performance in other ceramic systems.

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Section: Resultscontrasting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Low temperature self-densification of high strength bulk hexagonal boron nitride

Yang

Fang

et al. 2019

Nat Commun

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“…The advantages of RCVD include a uniform temperature distribution and the flexibility to use powders with different sizes and densities. 18), 19) In the present study, Ni and NiO nanoparticles were precipitated onto mesoporous silica and zeolite powders by RCVD. The effect of CVD parameters on the morphology, specific surface area, deposition features, and catalytic activities of the nanoparticles were investigated.…”

Section: Introductionmentioning

confidence: 97%

Precipitation of Ni and NiO nanoparticle catalysts on zeolite and mesoporous silica by rotary chemical vapor deposition

Zhang

Goto

2013

J. Ceram. Soc. Japan

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Ni and NiO catalytic nanoparticles were precipitated onto mesoporous silica and zeolite by rotary chemical vapor deposition (RCVD) using NiCp 2 as a precursor. The diameter of the nanoparticles precipitated onto zeolite increased from 5 to 50 nm when the oxygen flow rate (R O2 ) increased from 0 to 0.33 © 10 ¹6 m 3 s ¹1, whereas that of the nanoparticles precipitated onto mesoporous silica was 5 nm, independent of R O2 . The nanoparticles could be precipitated inside of the mesoporous silica pores but outside the zeolite pores. The highest H 2 production rate in the methanolsteam reforming reaction was 1150 © 10 ¹3 mol kg ¹1 s ¹1 at 633 K, which was achieved with a Ni/NiO catalyst on mesoporous silica, and this H 2 production rate is almost six times greater than that of the best Ni catalysts reported in literature.

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“…In addition, the physical rotation 34 , used in the VLS growth of CdS on the reduction site of the nanowire powder, was found to have an obvious effect on the H 2 evolution activity (Fig. 1).…”

Section: Introductionmentioning

confidence: 97%

Morphology Control of Energy-Gap-Engineered Nb2O5 Nanowires and the Regioselective Growth of CdS for Efficient Carrier Transfer Across an Oxide-Sulphide Nanointerface

Shinohara

Yamada

Sato

et al. 2017

Sci Rep

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Semiconductor nanowires with both nano- and micrometre dimensions have been used as effective materials for artificial photosynthesis; however, a single synthesis approach to provide rational control over the macroscopic morphology, which can allow for the high-throughput screening of photocatalytic performance, and carrier transfer between oxide and sulphide nanostructures has been poorly known. Our recent findings indicate that a single parameter, Nb foil thickness, in a vapor-phase synthesis method can alter the macroscopic morphology of resulting Nb2O5 nanowires. Thick Nb foil results in a free-standing Nb2O5 film, whereas a thinner foil leads to fragmentation to give a powder. During the synthesis process, a Rh dopant was provided through metal-organic chemical vapor deposition to reduce the Nb2O5 energy gap. Upon irradiation with visible light (λ > 440 nm), the free-standing nanowire film [Nb2O5:Rh-NW(F)] showed photoanodic current with a Faradaic efficiency of 99% for O2 evolution. Under identical irradiation conditions, the powdered counterpart [Nb2O5:Rh-NW(P)] showed activity for O2 evolution in the presence of an electron acceptor. The poor water-reduction ability was greatly enhanced by the Au-catalysed vapor-liquid-solid (VLS) growth of H2-evolving CdS onto the reduction sites of Nb2O5:Rh-NW(P) [Au/CdS/Nb2O5:Rh-NW(P)].

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Preparation of Ni-precipitated hBN powder by rotary chemical vapor deposition and its consolidation by spark plasma sintering

Cited by 32 publications

References 16 publications

Low temperature self-densification of high strength bulk hexagonal boron nitride

Low temperature self-densification of high strength bulk hexagonal boron nitride

Precipitation of Ni and NiO nanoparticle catalysts on zeolite and mesoporous silica by rotary chemical vapor deposition

Morphology Control of Energy-Gap-Engineered Nb2O5 Nanowires and the Regioselective Growth of CdS for Efficient Carrier Transfer Across an Oxide-Sulphide Nanointerface

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