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Title: CARBIDE COATINGS ON GRAPHITE

Abstract

A method has been developed for the uniform coating of graphite tubes with carbides of niobium, tantalum, and zirconinm by thermal decomposition of their respective halide vapors. Conditions of coating temperature and pressure are so chosen as to prevent the deposition of metal, but to permit the formation of the carbide as rapidly as carbon can diffuse to the surface. If the carbon diffusion can be made the rate-limiting step, the coating process becomes self- regulating and uniform thickness results. The limits of the temperature-pressure range have been determined experimentally for the thermal decomposition of zirconium iodide and of the chlorides and bromides of niobium, tantalum, and zirconium. With the successful development of coating equipment and definition of conditions, 99 blowpope test specimens were coated with uniform, continuous, and adherent layers of the carbides in three ranges of thickness, light (0.001 in.), medium (0.005 in.), and heavy (0.01 in.). Determinatlons were made of the coefficient for the diffusion of carbon in zirconium carbide as a function of temperature. Exploratory work on small specimens of graphite impregnated with 7 wt.% uranium indicated that the coating results were essentially unchanged, but that loss of uranium occurred. Means of avoiding the loss ofmore » uraninm are discussed. (auth)« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Battelle Memorial Inst., Columbus, Ohio
OSTI Identifier:
4265033
Report Number(s):
BMI-1200
NSA Number:
NSA-13-003805
DOE Contract Number:  
W-7405-ENG-92
Resource Type:
Technical Report
Resource Relation:
Other Information: Decl. Nov. 6, 1958. Orig. Receipt Date: 31-DEC-59
Country of Publication:
United States
Language:
English
Subject:
METALLURGY AND CERAMICS; CARBON; COATING; DECOMPOSITION; DIFFUSION; GRAPHITE; HALIDES; IMPREGNATION; LAYERS; LOSSES; MATERIALS TESTING; NIOBIUM CARBIDES; NIOBIUM COMPOUNDS; PIPES; PRESSURE; SURFACES; TANTALUM CARBIDES; TANTALUM COMPOUNDS; TEMPERATURE; THICKNESS; TUBES; URANIUM; VAPORS; ZIRCONIUM CARBIDES; ZIRCONIUM COMPOUNDS; ZIRCONIUM IODIDES

Citation Formats

Blocher, Jr., J. M., Ish, C. J., Leiter, D. P., Plock, L. F., and Campbell, I. E. CARBIDE COATINGS ON GRAPHITE. United States: N. p., 1957. Web. doi:10.2172/4265033.
Blocher, Jr., J. M., Ish, C. J., Leiter, D. P., Plock, L. F., & Campbell, I. E. CARBIDE COATINGS ON GRAPHITE. United States. https://doi.org/10.2172/4265033
Blocher, Jr., J. M., Ish, C. J., Leiter, D. P., Plock, L. F., and Campbell, I. E. 1957. "CARBIDE COATINGS ON GRAPHITE". United States. https://doi.org/10.2172/4265033. https://www.osti.gov/servlets/purl/4265033.
@article{osti_4265033,
title = {CARBIDE COATINGS ON GRAPHITE},
author = {Blocher, Jr., J. M. and Ish, C. J. and Leiter, D. P. and Plock, L. F. and Campbell, I. E.},
abstractNote = {A method has been developed for the uniform coating of graphite tubes with carbides of niobium, tantalum, and zirconinm by thermal decomposition of their respective halide vapors. Conditions of coating temperature and pressure are so chosen as to prevent the deposition of metal, but to permit the formation of the carbide as rapidly as carbon can diffuse to the surface. If the carbon diffusion can be made the rate-limiting step, the coating process becomes self- regulating and uniform thickness results. The limits of the temperature-pressure range have been determined experimentally for the thermal decomposition of zirconium iodide and of the chlorides and bromides of niobium, tantalum, and zirconium. With the successful development of coating equipment and definition of conditions, 99 blowpope test specimens were coated with uniform, continuous, and adherent layers of the carbides in three ranges of thickness, light (0.001 in.), medium (0.005 in.), and heavy (0.01 in.). Determinatlons were made of the coefficient for the diffusion of carbon in zirconium carbide as a function of temperature. Exploratory work on small specimens of graphite impregnated with 7 wt.% uranium indicated that the coating results were essentially unchanged, but that loss of uranium occurred. Means of avoiding the loss of uraninm are discussed. (auth)},
doi = {10.2172/4265033},
url = {https://www.osti.gov/biblio/4265033}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1957},
month = {6}
}