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Title: NIOBIUM CARBIDE COATING OF GRAPHITE TUBES

Abstract

Graphite tubes having a length-to-bore-diameter ratio of 430 were coated on the inside with uniform adherent layers of niobium carbide in thicknesses of 0.002 and 0.004 in. Intimate conformity to the graphite surface and improved uniformity were obtained by reacting NbCl/sub 5/ vapor with the graphite under pressuretemperature conditions thermodynamically unfavorable for the deposition of niobium by thermal dissociation of the chloride, but favorable for the formation of NbC. Thus, the rate of coating fermation depended primarily on the rate of diffusion of carbon through the carbide, which is a function of temperature and independent of vapor-flow considerations over a wide range, Although adherent coatings were obtained on a porous uraniumloaded graphite in the as-received condition, it was necessary to etch a more dense graphite to promote adherence. (auth)

Authors:
; ; ;
Publication Date:
Research Org.:
Battelle Memorial Inst., Columbus, Ohio
OSTI Identifier:
4265029
Report Number(s):
BMI-1296
NSA Number:
NSA-13-003807
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; ADHESION; CARBON; CHEMICAL REACTIONS; COATING; DECOMPOSITION; DENSITY; DIFFUSION; ETCHING; GRAPHITE; LAYERS; NIOBIUM; NIOBIUM CARBIDES; NIOBIUM CHLORIDES; POROSITY; PRESSURE; SURFACES; TEMPERATURE; THERMODYNAMICS; THICKNESS; TUBES; URANIUM; VAPORS

Citation Formats

Blocher, J.M. Jr., Browning, M.F., Leiter, D.P. Jr., and Campbell, I.E. NIOBIUM CARBIDE COATING OF GRAPHITE TUBES. United States: N. p., 1958. Web. doi:10.2172/4265029.
Blocher, J.M. Jr., Browning, M.F., Leiter, D.P. Jr., & Campbell, I.E. NIOBIUM CARBIDE COATING OF GRAPHITE TUBES. United States. doi:10.2172/4265029.
Blocher, J.M. Jr., Browning, M.F., Leiter, D.P. Jr., and Campbell, I.E. Wed . "NIOBIUM CARBIDE COATING OF GRAPHITE TUBES". United States. doi:10.2172/4265029. https://www.osti.gov/servlets/purl/4265029.
@article{osti_4265029,
title = {NIOBIUM CARBIDE COATING OF GRAPHITE TUBES},
author = {Blocher, J.M. Jr. and Browning, M.F. and Leiter, D.P. Jr. and Campbell, I.E.},
abstractNote = {Graphite tubes having a length-to-bore-diameter ratio of 430 were coated on the inside with uniform adherent layers of niobium carbide in thicknesses of 0.002 and 0.004 in. Intimate conformity to the graphite surface and improved uniformity were obtained by reacting NbCl/sub 5/ vapor with the graphite under pressuretemperature conditions thermodynamically unfavorable for the deposition of niobium by thermal dissociation of the chloride, but favorable for the formation of NbC. Thus, the rate of coating fermation depended primarily on the rate of diffusion of carbon through the carbide, which is a function of temperature and independent of vapor-flow considerations over a wide range, Although adherent coatings were obtained on a porous uraniumloaded graphite in the as-received condition, it was necessary to etch a more dense graphite to promote adherence. (auth)},
doi = {10.2172/4265029},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1958},
month = {10}
}