scholarly journals Deposition and Modification of Tantalum Carbide Coatings on Graphite by Laser Interactions

1992 ◽  
Vol 285 ◽  
Author(s):  
James Veligdan ◽  
D. Branch ◽  
P.E. Vanier ◽  
R.E. Barletta
Keyword(s):  
Chemical Vapor ◽  
Tantalum Carbide ◽  
Metal Halide ◽  
Graphite Substrate ◽  
Deposition Kinetics ◽  
Carbide Coatings ◽  
Hydrocarbon Gas ◽  
Bulk Substrate ◽  
Krf Excimer Laser ◽  
Laser Interactions

ABSTRACTGraphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000° C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCI5 gas near the substrate. The results of preliminary experiments using these techniques are described.

scholarly journals The Development of CVR Coatings for PBR Fuels

1993 ◽  
Vol 327 ◽  
Author(s):  
Robert. E. Barletta ◽  
P. E. Vanier ◽  
M. B. Dowell ◽  
J. A. Lennartz
Keyword(s):  
Pyrolytic Graphite ◽  
Chemical Vapor ◽  
Graphite Substrate ◽  
Refractory Carbide ◽  
Carbide Coatings ◽  
Large Numbers ◽  
Fuel Design ◽  
Fuel Particles ◽  
Particle Bed ◽  
Surrogate Fuel

AbstractParticle bed reactors (PBRs) are being developed for both space power and propulsion applications. These reactors operate with exhaust gas temperatures in the range of 2500 to 3000 K and fuel temperatures which may be hundreds of degrees higher. One fuel design for these reactors consists of uranium carbide encapsulated in either carbon or graphite. This fuel kernel must be protected from the coolant gas, usually H2, both to prevent attack of the kernel and to limit fission product release. Refractory carbide coatings have been proposed for this purpose. The typical coating process used for this is a chemical vapor deposition. Testing of other components have indicated the superiority of refractory carbide coatings applied using a chemical vapor reaction (CVR) process, however technology to apply these coatings to large numbers of fuel particles with diameters on the order of 500 gim were not readily available.A process to deposit these CVR coatings on surrogate fuel consisting of graphite particles is described. Several types of coatings have been applied to the graphite substrate. These include NbC in various thicknesses and a bilayer coating consisting of NbC and TaC with a intermediate layer of pyrolytic graphite. These coated particles have been characterized prior to test and the results of this characterization will be presented.

Determination of creep mechanisms in various silicon carbides via TEM

1986 ◽  
Vol 44 ◽  
pp. 484-487
Author(s):  
C. H. Carter ◽  
J. E. Lane ◽  
J. Bentley ◽  
R. F. Davis
Keyword(s):  
Heat Exchangers ◽  
Sintered Material ◽  
Polycrystalline Material ◽  
Chemical Vapor ◽  
Graphite Substrate ◽  
Second Phase ◽  
Reaction Bonding ◽  
Creep Mechanisms ◽  
Porous Sic

Silicon carbide (SiC) is the generic name for a material which is produced and fabricated by a number of processing routes. One of the three SiC materials investigated at NCSU is Norton Company's NC-430, which is produced by reaction-bonding of Si vapor with a porous SiC host which also contains free C. The Si combines with the free C to form additional SiC and a second phase of free Si. Chemical vapor deposition (CVD) of CH3SiCI3 onto a graphite substrate was employed to produce the second SiC investigated. This process yielded a theoretically dense polycrystalline material with highly oriented grains. The third SiC was a pressureless sintered material (SOHIO Hexoloy) which contains B and excess C as sintering additives. These materials are candidates for applications such as components for gas turbine, adiabatic diesel and sterling engines, recouperators and heat exchangers.

Gas products and carbon deposition kinetics in chemical vapor deposition from propylene

2010 ◽  
Vol 25 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Cui-ying LU ◽  
Lai-fei CHENG ◽  
Li-tong ZHANG ◽  
Chun-nian ZHAO
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Carbon Deposition ◽  
Chemical Vapor ◽  
Deposition Kinetics ◽  
Gas Products

Research progress on tantalum carbide coatings on carbon materials

Carbon ◽  
2022 ◽  
Vol 188 ◽  
pp. 544-545
Author(s):  
Xing-liang LIU ◽  
Yu DAI ◽  
Zhuo-jian WANG ◽  
Jian WU
Keyword(s):  
Carbon Materials ◽  
Tantalum Carbide ◽  
Research Progress ◽  
Carbide Coatings

scholarly journals Growth of Carbon Nanostructure on a Graphite Substrate by Plasma-Enhanced Chemical Vapor Deposition

Shinku ◽  
2003 ◽  
Vol 46 (5) ◽  
pp. 429-432 ◽  
Author(s):  
Shunsuke KAWAKI ◽  
Won-Chul MOON ◽  
Masamichi YOSHIMURA ◽  
Kazuyuki UEDA
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Graphite Substrate ◽  
Carbon Nanostructure

FORMATION OF SILICON CARBIDE COATINGS BY CHEMICAL VAPOR DEPOSITION (review). Part 1

2021 ◽  
pp. 100-111
Author(s):  
D.V. Sidorov ◽  
◽  
A.A. Schavnev ◽  
A.A. Melentev ◽  
◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Point Of View ◽  
Technological Parameters ◽  
Technical Literature ◽  
Pure Silicon ◽  
Carbide Coatings ◽  
Complex Process

The article provides an overview of the scientific and technical literature in the field of the formation of silicon carbide coatings by chemical vapor deposition (CVD). CVD is a complex process, approaches to which vary depending on the tasks being solved. Depending on the technological parameters, the initial reagents, the substrate for deposition, the type and design of the CVD reactors, it is possible to achieve both the deposition of pure silicon carbide and the co-deposition of silicon and/or carbon. In the first part of the article, attention is paid to the study of CVD from the point of view of the mechanisms of chemical reactions, the design of the deposition apparatus, the substrates for deposition.

Poly-Resistor Thin Film Formation by Excimer Laser Micromachine

2015 ◽  
Vol 780 ◽  
pp. 17-21
Author(s):  
A.F.M. Anuar ◽  
Yufridin Wahab ◽  
M.Z. Zainol ◽  
H. Fazmir ◽  
M. Najmi ◽  
...  
Keyword(s):  
Thin Film ◽  
Excimer Laser ◽  
Laser Energy ◽  
Film Formation ◽  
Chemical Vapor ◽  
Laser Pulses ◽  
Beam Size ◽  
Silicon Thin Film ◽  
Pressure Chemical ◽  
Krf Excimer Laser

A simple theoretical model and resistor fabrication for calculating the resistance of a polycrystalline silicon thin film is presented. The resistance value for poly-resistor is perfomed in terms of polysilicon thickness and its total area. The KrF excimer laser micromachine is used in assisting the resistor formation for a low pressure chemical vapor deposition (LPCVD) based polysilicon. Laser micromachine with three main parameters is used to aid the fabrication of the poly-resistor; namely as the pulse rate (i.e. number of laser pulses per second), laser beam size and laser energy. These parameters have been investigated to create the isolation between materials and also to achieve the desired poly-resistor shape. Preliminary results show that the 35 um beam size and 15 mJ of energy level is the most effective parameter to produce the pattern. Poly-resistor formation with 12 and 21 number of squares shows the total average resistance of 303.52 Ω and 210.14 Ω respectively. The laser micromachine process also significantly reduce the total time and number of process steps that are required for resistor fabrication.

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