Preparation and Characterization of SiC Coating on Graphite Substrate

2014 ◽  
Vol 602-603 ◽  
pp. 412-415 ◽  
Author(s):  
Yan Li Huo ◽  
Shu Guang Chen ◽  
Hai Long Liang ◽  
Chun Peng Wang ◽  
Jian Zhou ◽  
...  

High thermal conductivity and dense SiC coating were fabricated by chemical vapor deposition (CVD) on surface of different graphite at temperature of 1100°C. The results indicated that the thickness of the coating influences the quality of coating. There was no crack in coating when thickness of the coating is less than 0.3mm. The structure of graphite affected the reaction badly. When the graphite is coarse and porous the reaction is chemical vapor infiltration (CVI) and the interface of coating and substrate isnt obvious. When the graphite is dense and smooth, the coating is covered in surface of graphite, the interface is found between the coating and substrate. Optical microscope and SEM were used to observe the surface and cross-section morphology and microstructure of coatings. It shown coating and substrate had a good combination and the deposited grains mainly showed equiaxed form with the crystallite size of 30 nm at 1100°C.

2013 ◽  
Vol 377 ◽  
pp. 28-32 ◽  
Author(s):  
Xue Guang Huang ◽  
Yao Qi Li ◽  
Nan Zhao ◽  
Hui Shi ◽  
Xi Yao ◽  
...  

Over 1800 SiCf/SiC patents have been searched and identified in this work. SiCf/SiC technologies are emerging rapidly from 2005 in China. However, the extremely low proportion of patents owned by companies indicates that more effort and focus on SiCf/SiC are extremely needed to enable industrial application. Statistical results of worldwide patents reveal that the modification of the mechanical properties is the most urgent demand in industry; meanwhile, the analysis results show that the CVI/CVD (chemical vapor infiltration /chemical vapor deposition) method appears promising to enhance the mechanical properties, as well as to improve the thermal conductivity and stability, to lower the costs and to enhance the controllability of the product.


1994 ◽  
Vol 9 (11) ◽  
pp. 2839-2844 ◽  
Author(s):  
G. Popovici ◽  
S. Khasawinah ◽  
T. Sung ◽  
M.A. Prelas ◽  
B.V. Spitsyn ◽  
...  

The crystalline quality of a diamond film with two different preferential orientations (100) and (111), obtained in the same run by hot filament chemical deposition, has been studied. The quality of the film determined by Raman spectroscopy measurements was found to be nearly the same for both orientations. The second order Raman spectrum for diamond film was observed by using an infrared excitation.


MRS Advances ◽  
2019 ◽  
Vol 4 (3-4) ◽  
pp. 255-262
Author(s):  
Yong Xie ◽  
Guanfei Wang ◽  
Zhan Wang ◽  
Tang Nan ◽  
Haolin Wang ◽  
...  

ABTRACTIt has been demonstrated that the introduction of NaCl can significantly improve the quality of monolayer WS2 at the growth temperatures ranging from 700°C to 850°C by atmospheric pressure chemical vapor deposition (APCVD) without the assistant of hydrogen. Here, the influence of NaCl on the nucleation and growth of WS2 has been thoroughly investigated. The morphology and quality of WS2 grown with different temperatures are discussed by optical microscope, Raman and Photoluminescence (PL) spectra. It was found that amount of NaCl can efficiently influence the morphology and quality of WS2 crystals. PL intensity of WS2 crystal increases around three times from the center region to the edge of an individual domain, which may be attributed to the appearance of small triangle hollows formed during the growth at the edge of single crystal WS2.


Author(s):  
M.G. Burke ◽  
R.M. Young ◽  
C.B. Freidhoff ◽  
W.D. Partlow ◽  
H. Buhay

Amorphous refractory materials can be used in a number of optoelectronic applications when fabricated in multilayer structures. When the layers are deposited with very small thicknesses, heterostructures are produced. Such structures have an adjustable optical bandgap because the wavelength of light is much larger than the distance over which the composition of the film varies (layer to layer). Thicker multilayer structures can be fabricated on metallized, high thermal conductivity substrates. The purpose of the structure is to both protect and modify the substrate's properties. Two types of plasma-assisted chemical vapor deposition (PACVD) techniques have been employed to produce these structures.


2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Shigeo Maruyama ◽  
Rong Xiang

Vertically aligned single-walled carbon nanotubes (VA-SWNTs) is expected to be an extra-ordinal material for various optical, electrical, energy, and thermal devices. The recent progress in growth control and characterization techniques will be discussed. The chemical vapor deposition (CVD) growth mechanism of VA-SWNTs is studied based on the in situ growth monitoring by laser absorption during CVD. The growth curves are characterized by an exponential decay of the growth rate from the initial rate determined by ethanol pressure. The initial growth rate and decay of it are discussed with carbon over-coat on metal catalysts and gas phase thermal decomposition of precursor ethanol. For the precisely patterned growth of SWNTs, we recently propose a surface-energy-difference driven selective deposition of catalyst for localized growth of SWNTs. For a self-assembled monolayer (SAM) patterned Si surface, catalyst particles deposit and SWNTs grow only on the hydrophilic regions. The proposed all-liquid-based approach possesses significant advantages in scalability and resolution over state-of-the-art techniques, which we believe can greatly advance the fabrication of nanodevices using high-quality as-grown SWNTs. The optical characterization of the VA-SWNT film using polarized absorption, polarized Raman, and photoluminescence spectroscopy will be discussed. Laser-excitation of a vertically aligned film from top means that each nanotube is excited perpendicular to its axis. Because of this predominant perpendicular excitation, interesting cross-polarized absorption and confusing and practically important Raman features are observed. The extremely high and peculiar thermal conductivity of single-walled carbon nanotubes has been explored by nonequilibrium molecular dynamics simulation approaches. The thermal properties of the vertically aligned film and composite materials are studied by several experimental techniques and Monte Carlo simulations based on molecular dynamics inputs of thermal conductivity and thermal boundary resistance. Current understanding of thermal properties of the film is discussed.


Author(s):  
K.L. More ◽  
R.A. Lowden

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.


2015 ◽  
Vol 32 (6) ◽  
pp. 638
Author(s):  
Xingmin Cai ◽  
Xiaoqiang Su ◽  
Fan Ye ◽  
Huan Wang ◽  
Guangxing Liang ◽  
...  

2020 ◽  
Vol 13 (7) ◽  
pp. 075505
Author(s):  
Tomohiro Yamaguchi ◽  
Hiroki Nagai ◽  
Takanori Kiguchi ◽  
Nao Wakabayashi ◽  
Takuto Igawa ◽  
...  

Author(s):  
A. Ramos-Carrazco ◽  
J. A. Gallardo-Cubedo ◽  
A. Vera-Marquina ◽  
A. L. Leal-Cruz ◽  
J. R. Noriega ◽  
...  

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