Appeal No. 2004-2027
Application No. 09/670,189
mixture of Ar/10 volume % HCl was flowed in an external
chloride generator through a hafnium bed at 430 ºC. to
form hafnium tetrachloride containing a small amount
(e.g. less than 1 volume %) of zirconium tetrachloride.
The hafnium bed included a small concentration of
zirconium, such as less, than 1 weight % Zr.
Alternately, the coating gas mixture can be flowed
through a cogenerator having a hafnium bed and a
zirconium bed downstream of the hafnium bed to form
coating gas mixture... [Underscoring added.]
Smith discloses “sintered cemented carbide bodies coated
with thin and extremely wear resistant surface layers.” (Column
1, lines 6-8.) Specifically, Smith teaches a method of making an
aluminum oxide-coated cemented carbide body, wherein: a cemented
carbide substrate is contacted with a gas containing an aluminum
halide and a reducing agent at high temperature; titanium,
zirconium, and/or hafnium ions are added as dopants to the gas in
an amount of 0.03-0.5% of the total amount of supplied gas; and
the cemented carbide is coated with aluminum oxide, at least 85%
of which is in the kappa form. (Column 2, lines 26-37.)
According to Smith, the aluminum chloride may be provided in the
gas form by evaporation of the solid or liquid form. (Column 5,
lines 18-21.)
Basta ’963 discloses a CVD method in which a substrate
(e.g., nickel base superalloy) to be coated is supported in a
coating region of a reactor chamber and is heated to an elevated
reaction temperature. (Column 3, lines 19-23.) According to
Basta ’963, the method is especially useful for CVD aluminizing
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