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Title: COATING OF GRAPHITE WITH SILICON CARBIDE BY REACTION WITH VAPOR OF CONTROLLED SILICON ACTIVITY

Abstract

In the reaction of silicon halides with graphite to form silicon carbide, thermodynamic conditions were determined for the formation of SiC, free of elemental silicon. The use of these conditions was designed to limit the rate of coating formation by the rate of diffusion of carbon through the coating, and render the operation independent of the vapor-flow factors which normally limit the uniformity of vapor-deposited coatings. Although a wide range of pressure- temperaturecomposition conditions was explored, it was not possible to duplicate the success previously obtained in applying the method to NbC, TaC, TiC, and ZrC coatings. Fundamental differences in the characteristics of the carbides which may account for the difference in behavior are the lack of a range of homogeneity in beta SiC crystal structure, and the fact that SiC undergoes a modification from the cubic beta to a hexagonal form at l900 to 2000 deg C.There remains the prospect of forming a uniform SiC ''sponge'' by the present process which can be subsequently impregnated with metallic silicon to form an oxidation-resistant cpating. (auth) l6200 Preliminary results were obtained on the value that commercially pure Pu (95% Pu/sub 235/ and 5% Pu/subp 240/) has when used as nuclear fuel.more » The fuel value of Pu was taken to be such that the optimum Pu- fueled reactors have the same fuel costs as the optimum U-fueled reactors. For a given Pu value, that U enrichment which gave the minimum fuel cost was termed the optimum enrichment. This same procedure was used for the Pu-fueled reactors. For a given Pu value, the fuel cost was calculated as a function of Pu enrichment. That enrichment which gave minimum fuel cost was termed the optimum Pu enrichment. The fuel cost of the optimum U-fueled reactors was then plotted against the assumed Pu value. The same was done for the Pu-fueled reactors. The value of Pu corresponding to the crossing point of these curves was termed the fuel value. (W.L.H.)« less

Authors:
; ;
Publication Date:
Research Org.:
Battelle Memorial Inst., Columbus, Ohio
OSTI Identifier:
4234270
Report Number(s):
BMI-1349
NSA Number:
NSA-13-016199
DOE Contract Number:  
W-7405-ENG-92
Resource Type:
Technical Report
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-59
Country of Publication:
United States
Language:
English
Subject:
METALLURGY AND CERAMICS; CARBON; CHEMICAL REACTIONS; COATING; CONFIGURATION; CONTROL; CRYSTALS; DIFFUSION; GAS FLOW; GRAPHITE; HALIDES; HIGH TEMPERATURE; IMPREGNATION; LATTICES; NIOBIUM CARBIDES; OXIDATION; PRESSURE; SILICON CARBIDES; SILICON COMPOUNDS; STABILITY; TANTALUM CARBIDES; TEMPERATURE; THERMODYNAMICS; TITANIUM CARBIDES; VAPORS; ZIRCONIUM CARBIDES

Citation Formats

Blocher, J.M. Jr., Leiter, D.P. Jr., and Jones, R.P. COATING OF GRAPHITE WITH SILICON CARBIDE BY REACTION WITH VAPOR OF CONTROLLED SILICON ACTIVITY. United States: N. p., 1959. Web. doi:10.2172/4234270.
Blocher, J.M. Jr., Leiter, D.P. Jr., & Jones, R.P. COATING OF GRAPHITE WITH SILICON CARBIDE BY REACTION WITH VAPOR OF CONTROLLED SILICON ACTIVITY. United States. doi:10.2172/4234270.
Blocher, J.M. Jr., Leiter, D.P. Jr., and Jones, R.P. Mon . "COATING OF GRAPHITE WITH SILICON CARBIDE BY REACTION WITH VAPOR OF CONTROLLED SILICON ACTIVITY". United States. doi:10.2172/4234270. https://www.osti.gov/servlets/purl/4234270.
@article{osti_4234270,
title = {COATING OF GRAPHITE WITH SILICON CARBIDE BY REACTION WITH VAPOR OF CONTROLLED SILICON ACTIVITY},
author = {Blocher, J.M. Jr. and Leiter, D.P. Jr. and Jones, R.P.},
abstractNote = {In the reaction of silicon halides with graphite to form silicon carbide, thermodynamic conditions were determined for the formation of SiC, free of elemental silicon. The use of these conditions was designed to limit the rate of coating formation by the rate of diffusion of carbon through the coating, and render the operation independent of the vapor-flow factors which normally limit the uniformity of vapor-deposited coatings. Although a wide range of pressure- temperaturecomposition conditions was explored, it was not possible to duplicate the success previously obtained in applying the method to NbC, TaC, TiC, and ZrC coatings. Fundamental differences in the characteristics of the carbides which may account for the difference in behavior are the lack of a range of homogeneity in beta SiC crystal structure, and the fact that SiC undergoes a modification from the cubic beta to a hexagonal form at l900 to 2000 deg C.There remains the prospect of forming a uniform SiC ''sponge'' by the present process which can be subsequently impregnated with metallic silicon to form an oxidation-resistant cpating. (auth) l6200 Preliminary results were obtained on the value that commercially pure Pu (95% Pu/sub 235/ and 5% Pu/subp 240/) has when used as nuclear fuel. The fuel value of Pu was taken to be such that the optimum Pu- fueled reactors have the same fuel costs as the optimum U-fueled reactors. For a given Pu value, that U enrichment which gave the minimum fuel cost was termed the optimum enrichment. This same procedure was used for the Pu-fueled reactors. For a given Pu value, the fuel cost was calculated as a function of Pu enrichment. That enrichment which gave minimum fuel cost was termed the optimum Pu enrichment. The fuel cost of the optimum U-fueled reactors was then plotted against the assumed Pu value. The same was done for the Pu-fueled reactors. The value of Pu corresponding to the crossing point of these curves was termed the fuel value. (W.L.H.)},
doi = {10.2172/4234270},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1959},
month = {6}
}