Preparation of the highly dense ceramic–metal fuel particle with fine-grained tungsten layer by chemical vapor deposition for the application in nuclear thermal propulsion

Tungsten ◽  
2021 ◽  
Author(s):  
Li-Hua Guo ◽  
Feng Zhang ◽  
Lin-Yuan Lu ◽  
Yan You ◽  
Jun-Qiang Lu ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fuel Particle ◽  
Fine Grained ◽  
Tungsten Layer ◽  
Dense Ceramic ◽  
Metal Fuel

Influence of substrate annealing on the epitaxial growth of BaTiO3 thin films by metal-organic chemical vapor deposition

1997 ◽  
Vol 12 (6) ◽  
pp. 1625-1633 ◽  
Author(s):  
Cheol Seong Hwang ◽  
Mark D. Vaudin ◽  
Gregory T. Stauf
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Nucleation Kinetics ◽  
Fine Grained ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
Mgo Substrate

BaTiO3 thin films were deposited by metal-organic chemical vapor deposition at 840 °C on two differently treated (100) MgO single crystal substrates. One MgO substrate was only mechanically polished and the other substrate was polished and then annealed at 1100 °C for 4 h in oxygen. Observation by transmission electron microscopy showed that the BaTiO3 thin film deposited on the unannealed substrate was fine-grained and that the whole film was epitaxial (100) in nature. In contrast, the film deposited on the annealed substrate consisted of large, (100)-oriented, epitaxial grains within which were distributed (110)-oriented grains with random in-plane orientations. These differences in BaTiO3 films deposited on differently treated substrates are discussed with reference to the surface structure of the MgO substrate and nucleation kinetics of BaTiO3 thin films on MgO.

Preparation of Silicon Carbide Coating Layer by Fluidized Bed Chemical Vapor Deposition Using a Halogen-Free Precursor

2016 ◽  
Vol 697 ◽  
pp. 846-851 ◽  
Author(s):  
Ma Lin Liu ◽  
Rong Zheng Liu ◽  
Jia Xing Chang ◽  
You Lin Shao
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Fluidized Bed ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Chemical Vapor Deposition Method ◽  
Fuel Particle ◽  
Coated Materials

Tristructural-isotropic (TRISO) particle, with spherical ceramic fuel particle kernels followed by three layers of pyrolytic carbon and one layer of silicon carbide (SiC), has been successful now in high temperature gas cooled reactor (HTGR). The silicon carbide (SiC) layer used in TRISO coated fuel particles is normally produced at high temperatures (~1600°C) via fluidized bed chemical vapor deposition from methyltrichlorosilane (MTS) in a hydrogen environment. The precursor is strong corrosive and the process is not environmentally friendly. In this work, hexamethyldisilane (HMDS) was used instead of MTS and the deposition behavior was investigated via fluidized bed chemical vapor deposition method. Different experimental parameters were tested, such as deposition temperature (800~1450°C) and gas flow ratio of Ar: H2. The deposition rates were obtained and compared. It was found that the optimization parameters of highest deposition rate is 1000°C with the ratio of Ar: H2 of 1:1. The microstructures of the products were further investigated by SEM, XRD and Raman scattering. From the X-ray diffraction pattern it could be inferred that the β-SiC phase was obtained, and free carbon was also found in deposition products. Different types of SiC layer, including dense and porous layer can be prepared. The experimental results validated that HMDS was an alternative precursor for preparing the SiC layer in producing the TRISO particle and other SiC-coated materials in lower temperatures

Fine‐grained 3C‐SiC thick films prepared via hybrid laser chemical vapor deposition

2019 ◽  
Vol 102 (9) ◽  
pp. 5668-5678 ◽  
Author(s):  
Youfeng Lai ◽  
Hong Cheng ◽  
Zhenglin Jia ◽  
Qizhong Li ◽  
Meijun Yang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Thick Films ◽  
Chemical Vapor ◽  
Laser Chemical Vapor Deposition ◽  
Fine Grained

Coating of Small Particles by Chemical Vapor Deposition While the Particles are Fluidized

1994 ◽  
Vol 372 ◽  
Author(s):  
J. L. Kaae
Keyword(s):  
Chemical Vapor Deposition ◽  
Fluidized Bed ◽  
Vapor Deposition ◽  
Collection Efficiency ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Small Particles ◽  
Two Phase ◽  
Fine Grained ◽  
Particle Bed

AbstractCoating of small particles is often employed to impart special properties to the particles. One process that has been used to accomplish this is chemical vapor deposition while the particles are fluidized. Because the depositing solids can plug small orifices, the gas distributors used for chemical vapor deposition in a fluidized bed of particles are different from those used for most other fluidized bed processes. The turbulent mixing of the gases by the particle bed and the high collection efficiency of depositing species by the large surface area of the particle bed can produce unique coating microstructures. Examples of these unique microstructures are those of isotropic pyrolytic carbon, fine-grained silicon carbide and carbon-silicon two-phase mixtures.

Preparation of Fine Grained SiC Layer by Fluidized Bed Chemical Vapor Deposition with Pulsed Propylene

2016 ◽  
Vol 99 (6) ◽  
pp. 1870-1873 ◽  
Author(s):  
Rongzheng Liu ◽  
Malin Liu ◽  
Ziliang Wang ◽  
Youlin Shao ◽  
Jiaxing Chang ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Fluidized Bed ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fine Grained
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