Preparation and Characterization of SiC Nanoparticles for ATF-FCM

2018 ◽  
Vol 281 ◽  
pp. 22-27
Author(s):  
Zhao Chen ◽  
Rong Zheng Liu ◽  
Jia Xing Chang ◽  
Ma Lin Liu
Keyword(s):  
Gas Flow ◽  
Chemical Vapor ◽  
Pure Hydrogen ◽  
Fukushima Accident ◽  
Flow Rates ◽  
Sic Nanoparticles ◽  
Hydrogen Flow ◽  
Different Temperatures ◽  
Carrier Gas Flow

Accident Tolerant fuel (ATF) concept was put forward after the Fukushima accident. Among different kinds of ATF, Fully Ceramic Microencapsulated Fuels (FCM) have been paid more and more attention in recent years. SiC matrix is one of the important constituent parts in FCM fuel system, which is sintered from kinds of SiC powders. In this study, SiC nanoparticles were prepared by Fluidized Bed Chemical Vapor Deposition (FB-CVD) method using Hexamethyldisilane (HMDS) as precursor, aimed at reducing the sintering temperature and pressure of FCM-SiC matrix. Experiments of different temperatures with different argon gas ratios were carried out. It was found that good crystal SiC could be obtained from 850°C to 1250°C, under pure hydrogen or H2: Ar=15:1. Different H2 carrier gas flow rate tests were also conducted. With the increase of hydrogen flow rates, the SiC was transformed from 3C-SiC to other types, such as 6H or 15R, but no significant effect was found on particle shape. Based on the characterizations of XRD, SEM and TEM, the results showed the spherical SiC nanoparticles could be obtained as well as 20 nanometers in diameter at the condition of 1150°C, H2: Ar=15:1, under different hydrogen flow rates. Different hydrogen flow rates had little influence on the particle size of SiC nanoparticles.

The Effects of Hydrogen Flowrate during Pre-Annealing on Graphene Growth by Chemical Vapor Deposition Using Methanol as a Liquid Carbon Precursor

2019 ◽  
Vol 290 ◽  
pp. 107-112
Author(s):  
Raed Abdalrheem ◽  
Fong Kwong Yam ◽  
Abdul Razak Ibrahim ◽  
Khi Poay Beh ◽  
Hwee San Lim ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Light Transmittance ◽  
High Hydrogen ◽  
Flow Rates ◽  
Hydrogen Flow ◽  
Number Of Layers ◽  
Crystallite Sizes ◽  
Grown Graphene

Studying an influence of several parameters on Chemical Vapor Deposition (CVD) used for graphene synthesis is crucial to optimizing the graphene quality to be Compatible with advanced devices. The effect of different hydrogen (H2) flow-rates (0, 50, 100, 150, 200, 250, and 300 sccm) during the pre-annealing process on CVD grown graphene have been reported. This study revealed that hydrogen flow rates during annealing changed the surface roughness/smoothness of the copper substrates. For high hydrogen flow rates, the smoothing effect was increased. Furthermore, the annealed graphene samples emerged a deferent number of layers because of morphological surface changes. According to Raman D- to G-band intensity ratios (ID/IG), the graphene quality was influenced by the annealing hydrogen flowrate. The visible light transmittance values of the grown graphene samples confirmed a few number of layers (mono to seven-layer). Mostly, the samples which annealed under moderate hydrogen flow rates showed less defects intensities and higher crystallite sizes.

EFFECT OF ACETYLENE FLOW RATE ON ELECTROSORPTION CAPACITY OF CARBON NANOTUBE AND NANOFIBER COMPOSITE FILM ELECTRODES

2007 ◽  
Vol 14 (01) ◽  
pp. 135-139 ◽  
Author(s):  
X. Z. WANG ◽  
L. K. PAN ◽  
M. G. LI ◽  
Y. W. CHEN ◽  
R. M. CHENG ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Composite Film ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Nanofiber Composite ◽  
Spectra Analysis ◽  
Flow Rates ◽  
Hydrogen Flow ◽  
Successful Removal ◽  
Desalination Technology

Electrosorption of carbon nanotube and nanofiber (CNT–CNF) composite film electrodes was studied as a new desalination technology. The CNT–CNF composite film electrodes were grown on nickel sheets by low pressure thermal chemical vapor deposition. Different growth conditions at different acetylene flow rates of CNT–CNF composite film electrodes have been performed to obtain different crystallinities. The electrosorption experiments and Raman spectra analysis show the successful removal of ions with CNT–CNF composite film electrodes, depending on the optimal degree of crystalline perfection. In our work, optimal electrosorption was realized for the CNT–CNF composite film electrodes growing at 550°C with the acetylene and hydrogen flow rates of 30 and 200 sccm.

Characterization of Gan/Sapphire Interface and the Buffer Layer by TEM/AFM

2001 ◽  
Vol 7 (S2) ◽  
pp. 330-331
Author(s):  
B. Shea ◽  
Q. Sun-Paduano ◽  
D. F. Bliss ◽  
M. C. Callahan ◽  
C. Sung
Keyword(s):  
Buffer Layer ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Wide Band ◽  
Buffer Layers ◽  
Organic Chemical ◽  
Wide Band Gap ◽  
Tem Analysis ◽  
Flow Rates ◽  
Device Applications

Interest in wide band gap III-V nitride semiconductor devices is increasing for optoelectronic and microelectronic device applications. to ensure the highest quality, TEM analysis can characterize the substrate and buffer layer interface. Measurements taken by TEM reveal the density of dislocations/cm2 and the orientation of Burger's vectors. This information allows for changes to be made in deposition rates, temperatures, gas flow rates, and other parameters during the processing.The GaN/sapphire samples grown at AFRL were produced in two consecutive steps, first to provide a thin buffer layer, and the other to grow a lum thick epitaxial film. Both growth steps were prepared using metallic organic chemical vapor deposition (MOCVD) in a vertical reactor. Buffer layers were prepared using a range of temperatures from 525 to 535°C and with a range of flow rates and pressures in order to optimize the nucleation conditions for the epitaxial films.

Copper Films Prepared by Metal Organic Chemical Vapor Deposition (MOCVD) Process Using Copper (Acetylacetonate) and Water Vapor as Reactants: The Impact of Water Vapor

1992 ◽  
Vol 282 ◽  
Author(s):  
Yu-Neng Chang
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Gas Flow Rate ◽  
Cu Films ◽  
Metal Organic ◽  
Carrier Gas Flow ◽  
Organic Chemical Vapor Deposition

ABSTRACTBy using the strong reductive potential of copper acetylacetone (Cu(acac)2) when Cu(acac)2) was thermally decomposed, copper metal films were prepared by metal organic chemical vapor deposition (MOCVD) process using sublimed Cu(acac)2 vapor and water vapor as reactants, at one atmosphere pressure. According to thermodynamic calculations, Cu films could be prepared by MOCVD process with a high ratio of partial pressures for water vapor and Cu(acac)2 vapor (PH2O/Pcu(acac)2>30) In this paper, the impacts of MOCVD processing parameters such as watervapor partial pressure, total carrier gas flow rate, and precursor partial pressure on film composition and microstructure were investigated. Deposition temperature is the primary processing parameter affecting film stoichiometry. In a specific deposition temperature window, from 370°C to 400°C, polycrystalline Cu films with Cu [111] preferential orientation were deposited. ER and XRD results indicated that films deposited at temperature lower than 350°C contain copper oxide phase with poor crystal structure. By comparing the values of X-ray Auger Electron Spectroscopy (XAES) and Auger parameter (αAu) from photoelectrons of Cu films and standards from reference compounds, die principle oxidation state of copper in these films was determined as Cu(0). The deposition results indicated that a water vapor partial pressure above 10 torr is necessary to produce Cu films. As indicated by SEM, Increasing the carrier gas flow rate, above 600 sccm, can reduce the average temperature profile in the thermal boundary layer above the substrate surface, retard the gas phase reaction rate, presumably eliminate the homogeneous nucleation, and deposit smooth Cu films.

Effects of Temperature on Carrier-Gas Flow Rates in Packed and Capillary Columns.

1966 ◽  
Vol 38 (1) ◽  
pp. 7-9 ◽  
Author(s):  
Gary. Horlick ◽  
W. E. Harris ◽  
H. W. Habgood
Keyword(s):  
Gas Flow ◽  
Capillary Columns ◽  
Flow Rates ◽  
Carrier Gas ◽  
Effects Of Temperature ◽  
Carrier Gas Flow

Synthesis and Study of Carbon Nanotubes by the Spray Pyrolysis Method Using Different Carbon Sources.

2015 ◽  
Vol 1752 ◽  
pp. 31-38
Author(s):  
Beatriz Ortega Garcia ◽  
Oxana Kharissova ◽  
Francisco Servando Aguirre-Tostado ◽  
Rasika Dias
Keyword(s):  
Carbon Nanotubes ◽  
Spray Pyrolysis ◽  
Gas Flow ◽  
Carbon Sources ◽  
Spray Pyrolysis Method ◽  
Solution Flow ◽  
Synthesis Time ◽  
Transmission Electron ◽  
Carrier Gas Flow

ABSTRACTAccording to the reports of Z.E. Horvath et al [1] and Liu Yun-quan et al [5], carbon nanotubes can be synthesized by spray pyrolysis from different carbon sources (n-pentane, n-hexane, n-heptane, cyclohexane, toluene and acrylonitrile) and several metallocene catalysts (ferrocene, cobaltocene and nickelocene). This paper describes two different existing methods for growth of carbon nanotubes and the influence of applied parameters (oven temperature, synthesis time, catalyst concentration, carrier gas flow and solution flow) on the CNT's morphology. Also, a possible influence of number of carbons in carbon sources and structures of their compounds (linear or aromatic) on properties of formed carbon nanotubes. Transmission Electron Microscopy (TEM), Infrared Spectroscopy (FTIR) and Raman spectroscopy were applied for characterization of obtained materials.

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