Interference No. 103,995 Paper 29
Morel v. Sekhar Page 11
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between 600 and 700 C” (c. 2, ll. 34-45). The ‘084 patent defines the invention as “a
coating for protecting materials against reactions with atmosphere at high temperatures,
characterized in that the coating contains zirconium diboride and colloidal silica” (c. 2, ll. 6-
9).
31. Dr. Laurent further testified that
The Morel patent [i.e., the ‘084 patent] discloses the formation of a
coating by vitrification of a mixture of zirconium diboride and colloidal silica.
By my personal understanding of the process, this vitrification occurs in
several steps:
1) Oxidation of ZrB2
ZrB + 5/2 O 6 ZrO + B O (boric acid)2 2 2 2 3
2) Boric oxide reacts with silica
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B O + SiO 6 B O :SiO which forms a eutectic at 372 C2 3 2 2 3 2
[MAEx 1, p. 2, ¶ 4, emphasis added.]
The glassy material of formula B O :SiO fills the pores and coats the
2 3 2
remaining grains, thereby producing a coating impervious to oxygen. [MAEx
1, p. 2, ¶ 5.]
When added to the mixture, SiC strengthens the coating but does not
necessarily take part in the vitrification reaction, since SiC starts to oxidize
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at 1300 - 1400 C. [MAEx 1, p. 3, ¶ 6.]
32. Dr. Laurent further testified that
When the weight ratio of zirconium diboride to silica is at least about
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1:1, vitrification takes place at 600-700 C. With lesser amounts of
zirconium diboride, the formation of the glassy eutectic composition is
greatly diminished, although, as disclosed in US Patent 5,364,513 the
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particles may be sintered at temperatures in excess of 900 C. [MAEx 1, p. 3,
¶ 7.]
33. Dr. Laurent still further testified that
I believe that the vitrification which takes place when the weight ratio
the alkali and alkaline earth or heavy metals (p. 298).
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