Si/SiC-Based Layer Deposited on Boron Carbide Particles via CVD

2014 ◽  
Vol 602-603 ◽  
pp. 270-273 ◽  
Author(s):  
Yu Feng Xu ◽  
Hong Qiang Ru ◽  
Xin Yan Yue
Keyword(s):  
Low Temperature ◽  
Surface Morphology ◽  
Boron Carbide ◽  
Energy Dispersive Spectrometer ◽  
Protective Layer ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Binding Phase ◽  
Nodular Growth ◽  
Carbide Particles

The application of B4C as structural materials has been restricted largely because of its poor sinter-ability. Compared with pressure-less and hot pressing methods, sintering the B4C via the reaction-bonded boron carbide (RBBC) can to great extent circumvent such problem, which can even be conducted at low temperature, when Si/Si-based alloy was used as binding phase. However molten Si/Si-based alloy infiltrated into performs of bare B4C powders can strongly react with and significantly consume B4C particles based on molten infiltration reaction method. The present study aims to encapsulate B4C particles with a protective layer to block off its contact with molten Si/ Si-based alloy via chemical vapor deposition (CVD) method in CH3SiCl3(MTS)-H2-Ar system at low temperature (900-1100 °C) under atmospheric pressure. The phase composition and surface morphology of encapsulated B4C particles were studied using X-ray diffraction (XRD) , scanning electron microscopy (SEM) plus energy dispersive spectrometer (EDS), respectively. It was found that the deposition temperatures have a significant effect on microstructure and composition of deposited coating. The studies on surface morphology revealed that spine-like crystals, nodular growth, island structure and whiskers can be deposited onto the surface of boron carbide particles. When deposited at 900-1000 °C,the coatings is Si + SiC co-deposition, while pure SiC coatings form only at as high deposition temperature at 1050 °Cand 1100 °C.

Low Temperature Large Scale CVD Synthesis of Nano Onion-Like Fullerenes

2012 ◽  
Vol 490-495 ◽  
pp. 3211-3214 ◽  
Author(s):  
Lei Shan Chen ◽  
Cun Jing Wang
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Aluminum Hydroxide ◽  
Large Scale ◽  
Iron Catalyst ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Naoh Solution ◽  
Synthesis Reactions

Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

scholarly journals Получение карбида бора в низковольтной электрической дуге постоянного тока, инициированной в открытом воздушном пространстве

2018 ◽  
Vol 44 (14) ◽  
pp. 26 ◽  
Author(s):  
А.Я. Пак ◽  
Г.Я. Мамонтов
Keyword(s):  
Boron Carbide ◽  
Arc Discharge ◽  
Electron Microscopic Examination ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Vacuum Equipment ◽  
X Ray ◽  
Gas Atmosphere ◽  
Average Size ◽  
Carbide Particles

AbstractWe describe a method of obtaining ultrafine boron carbide (B_13C_2) powder using the effect of a dc electric arc on a mixture of initial reactants containing carbon and boron. A peculiarity of the proposed method is that it can be implemented using arc discharge operating in open air without any vacuum equipment and protective inert gas atmosphere. X-ray diffraction data showed that the synthesized product in the general case contained three crystalline phases: boron carbide (B_13C_2), graphite (C), and boron oxide (B_2O_3). Electron-microscopic examination showed that the average size of boron carbide particles ranged from ~50 nm to ~2 μm.

scholarly journals Boron Carbide Nanowires from Castor Oil for Optronic Applications: A Low-Temperature Greener Approach

2020 ◽  
Author(s):  
H. V. Saritha Devi ◽  
M. S. Swapna ◽  
S SANKARARAMAN
Keyword(s):  
Low Temperature ◽  
Boron Carbide ◽  
Castor Oil ◽  
Light Emission ◽  
Bandgap Energy ◽  
X Ray Diffraction ◽  
Blue Light Emission ◽  
Tauc Plot ◽  
Plot Analysis ◽  
Cie Plot

Abstract The development of one-dimensional nanostructures has revolutionized electronic and photonic industries because of their unique properties. The present paper reports the low-temperature green synthesis of boron carbide nanowires, of diameter 14 nm and length 750 nm, by the condensation method using castor oil as the carbon precursor. The nanowires synthesized exhibit beaded chain morphology, and bandgap energy of 2.08 eV revealed through the Tauc plot analysis. The structure of boron carbide nanowires is revealed by Fourier transform infrared spectroscopy and X-ray diffraction analyses. The photoluminescence study reveals the nanowire's blue light emission capability under ultraviolet excitation, which is substantiated by the CIE plot suggesting its potential in photonic applications.

Preparation of Boron Carbide Nanoparticles by Carbothermal Reduction Method

2004 ◽  
Vol 848 ◽  
Author(s):  
Baohe Chang ◽  
Bonnie Gersten ◽  
Jane W. Adams ◽  
Steve Szewczyk
Keyword(s):  
Boron Carbide ◽  
Reduction Method ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Boron Powder ◽  
X Ray ◽  
Transmission Electron ◽  
Crystalline Boron ◽  
Average Size ◽  
Carbide Particles

ABSTRACTA carbothermal reaction process was employed to synthesize nano-sized boron carbide particles. The reactions were carried out by heating a mixture of boric oxide powder and amorphous carbon reactant under a flow of argon atmosphere in a conventional high temperature tube furnace at 1350–1700 °C for 1–4 h. In order to obtain stoichiometric powder product, additional pure boron powder was added to the reaction mixture to compensate for the boron loss in the form of B2O2/B2O3vapor during the reaction. The effect of the structure and morphology of the precursor materials on that of the products was also investigated. X-ray diffraction (XRD) studies indicated that the powdered product prepared under optimized reaction conditions was crystalline boron carbide. Transmission electron microscopy (TEM) observations showed that the product nanoparticles ranged from 50 nm to 250 nm with the average size between 100 nm and 150 nm depending on the reaction conditions. Some boron carbide particles were as small as 50 nm. Energy dispersive spectroscopy (EDS) was also used to determine the stoichiometry of the boron carbide nanoparticle products.

Formation of an Interfacial Buffer Layer for 3C-SiC Heteroepitaxy on AlN/Si Substrates

2014 ◽  
Vol 778-780 ◽  
pp. 251-254 ◽  
Author(s):  
Kazuki Meguro ◽  
Tsugutada Narita ◽  
Kaon Noto ◽  
Hideki Nakazawa
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Surface Morphology ◽  
Buffer Layer ◽  
Vapor Deposition ◽  
Intermediate Layer ◽  
Chemical Vapor ◽  
Si Substrates ◽  
Pressure Chemical ◽  
Sic Films

We have formed a SiC interfacial buffer layer on AlN/Si substrates at a low temperature by low-pressure chemical vapor deposition (LPCVD) using monomethylsilane (CH3SiH3; MMS), and grew 3C-SiC films on the low-temperature buffer layer by LPCVD using MMS. We investigated the surface morphology and crystallinity of the grown SiC films. It was found that the formation of the SiC buffer layer suppressed the outdiffusion of Al and N atoms from the AlN intermediate layer to the SiC films and further improved the surface morphology and crystallinity of the films.

Aqueous Corrosion Investigation of Yb Doped Lead Oxychloride Tellurite Glass

2015 ◽  
Vol 1107 ◽  
pp. 477-482
Author(s):  
Khaidzir Hamzah ◽  
M. Abdullah Izat Yassin ◽  
Ahmad Farhan Suffian ◽  
Md. Rahim Sahar ◽  
Sib Krishna Ghoshal
Keyword(s):  
Corrosion Rate ◽  
Surface Morphology ◽  
Structural Characteristics ◽  
Glass Network ◽  
Protective Layer ◽  
X Ray Diffraction ◽  
Aqueous Corrosion ◽  
Electron Microscopic ◽  
Corrosion Investigation ◽  
Corrosion Rate Measurement

Series of glass based on (80-x)TeO2-10PbO-10PbCl2-xYb2O3 where 0.0 ≤ x ≤ 3.0 were successfully prepared via melt quenching technique. The corrosion rate measurement was carried out by immersing the glass in various pH solutions in the range of pH 2 to 11. The alteration in surface morphology and structural characteristics was examined using field emission scanning electron microscopic and X-ray diffraction measurements. The corrosion investigations showed that the corrosion rate of the glass decreased over time due to the formation of protective layer on the glass surface. Furthermore, the increase in Yb amount in the glass network was found to enhance the corrosion resistance. This attributed to the enhancement of glass compactness. However, as the amount reached 2 mol%, the ability to resist corrosion decreased due to inability of Yb to participate in the structure. The FESEM micrographs indeed revealed the differences of surface morphology of glass after immersion in various pH solutions. It is demonstrated that the corrosion of acid and alkali occurred differently where acidic attacks were faster compared to alkali and distilled water.

Electroless Copper Coating on Boron Carbide Particles by Using Copper Activation Method

2014 ◽  
Vol 576 ◽  
pp. 127-131
Author(s):  
Wei Wang ◽  
Qiu Lin Li ◽  
Wei Liu ◽  
You Wei Yao ◽  
Xue Jun Li
Keyword(s):  
Boron Carbide ◽  
Activation Method ◽  
Complexing Agent ◽  
X Ray Diffraction ◽  
Electroless Coating ◽  
X Ray ◽  
Structure And Morphology ◽  
Coating Layers ◽  
Average Size ◽  
Carbide Particles

The present work is focused on electroless coating of copper nanolayer onto boron carbide (B4C) particle surfaces by using copper activation method. The B4C particles used are approximately 18.25μm in average size. B4C particle surfaces were washed by acetone and activated through copper activation method. In the electroless coating bath, copper sulfate, EDTA-2Na and seignette salt, hydrazine hydrate were used as the copper catalytic centers source, complexing agent and reducing agent respectively. The structure and morphology of the coating layers were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD and SEM observations show that B4C particle surfaces were successfully coated by a homogeneous and continuous copper layer.

Dielectric Property of Si3N4/SiBCN Composite Ceramics Doped with SiC

2013 ◽  
Vol 748 ◽  
pp. 91-95
Author(s):  
Fang Ye ◽  
Li Tong Zhang ◽  
Xiao Wei Yin ◽  
Ya Jun Zhang ◽  
Yong Sheng Liu ◽  
...  
Keyword(s):  
Energy Dispersive Spectrometer ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Sic Nanoparticles ◽  
X Ray ◽  
Absorbing Material ◽  
Absorbing Property ◽  
Sic Film

Si3N4/SiBCN composite ceramics were prepared by infiltrating and pyrolyzing liquid polyborosilazane in porous Si3N4 ceramics. To increase their wave-absorbing ability, SiC nanoparticles and SiC film obtained by chemical vapor infiltration were separately introduced into the composite ceramics. The surface morphology, element and phase composition of ceramics were analyzed by means of scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction. Dielectric and electromagnetic wave absorbing property researches show that the permittivity and dielectric loss of the ceramics were effectively improved and the electromagnetic reflection coefficient was visibly decreased when SiC was loaded. It is indicated that SiC is an effective dielectric lossy absorbent, and the Si3N4/SiBCN composite ceramics containing SiC possess the great potential in the application of wave-absorbing material.

Modification of Optical Surfaces Employing CVD Boron Carbide Coatings

1991 ◽  
Vol 250 ◽  
Author(s):  
Richard A. Lowden ◽  
Laura Riester ◽  
M. Alfred Akerman
Keyword(s):  
Optical Properties ◽  
Boron Carbide ◽  
Chemical Vapor ◽  
Surface Characteristics ◽  
Incident Radiation ◽  
X Ray Diffraction ◽  
Satellite Systems ◽  
Optical Surfaces ◽  
Carbide Coatings ◽  
Service Environments

AbstractNon-reflective or high emissivity optical surfaces require materials with given roughness or surface characteristics wherein interaction with incident radiation results in the absorption and dissipation of a specific spectrum of radiation. Coatings have been used to alter optical properties, however, extreme service environments, such as experienced by satellite systems and other spacecraft, necessitate the use of materials with unique combinations of physical, chemical, and mechanical properties. Thus, ceramics such as boron carbide are leading candidates for these applications. Boron carbide was examined as a coating for optical baffle surfaces. Boron carbide coatings were deposited on graphite substrates from BCl3, CH4, and H2 gases employing chemical vapor deposition (CVD) techniques. Parameters including temperature, reactant gas compositions and flows, and pressure were explored. The structures of the coatings were characterized using electron microscopy and compositions were determined using x-ray diffraction. The optical properties of the boron carbide coatings were measured, and relationships between processing conditions, deposit morphology, and optical properties were determined.

MOCVD Growth of GaAs on Si with Low Temperature Preheating Process

1992 ◽  
Vol 259 ◽  
Author(s):  
N. Takagi ◽  
T. Eshita ◽  
S. Miyagaki ◽  
M. Kimura ◽  
K. Takasaki
Keyword(s):  
Low Temperature ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Mocvd Growth ◽  
Atomic Force ◽  
Preheating Temperature ◽  
Wet Chemical ◽  
Better Than

ABSTRACTA low temperature preheating process is developed for metalorganic chemical vapor deposition (MOCVD) growth of GaAs on wet chemical pretreated Si substrates. NH4 OH/H2 O2 is found to be most effective in decreasing the preheating temperature among the chemicals we tried: NH4 OH/H2 O2, H2SO4 /H2O2, or hot HNO3. By using NH4OH/H2 O2, the preheating temperature is reduced from 1000°C to 875°C. X-ray diffraction measurements and surface observations with an atomic force microscope (AFM) show that the GaAs film quality obtained with the 875 °C preheating process is better than that obtained with 1000°C preheating.

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