Appeal No. 95-3422
Application 07/891,132
the art would have wanted to solve them. Accordingly, we
reverse the examiner’s rejections of Claims 1-9 and 12-21.
Claims 10 and 11 present a slightly different issue
because Richerson describes a silicon nitride electrical
insulating layer or jacket integrally bonded to a silicon
carbide/silicon nitride heating element (Richerson, col. 2, l.
49-68). The examiner argues that it would have been prima
facie obvious in view of Richerson’s teaching to apply a high
temperature resistant silicon nitride electrical insulating
layer or jacket to the
heating element of Levin’s reactor. On consideration of the
prior art teaching as a whole, we find the examiner’s argument
untenable.
First, Richerson describes a silicon nitride electrical
insulating layer or jacket hot-pressed to a silicon carbide/
silicon nitride heating element. Richerson does not indicate
that silicon nitride electrical insulating layers or jackets
may be applied to, or are useful as electrical insulators for,
heating elements generally. See Richerson’s Example 1, col.
5, l. 35-51:
A graphite mold set-up was assembled with the exception
of the top plate. An 81.0 gram quantity of the silicon
nitride powder was spread in the mold, followed by 21.7
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