Appeal 2007-0882
Application 10/702,987
cracks 7 and defects in the outer surface 5. It is important to be able to
repair the surface cracks 5 without affecting the internal cooling passages
3.” Col. 4, ll. 56-60.
4) In White’s process, “cracks with openings in the outermost surface
are coated by Hyper Velocity Oxy-Fuel or other thermal spray process,
such as low pressure plasma deposition, to seal the crack region. The
preferred method of coating is the Hyper Velocity Oxy-Fuel process. The
low pressure plasma deposition process, being chamber contained and
therefore more costly and limiting, would be used only if the reduced
atmosphere from the process was found to [be] beneficial in reducing
oxidation and gas volume in the cracked surface region.” Col. 5, ll. 8-17.
5) White teaches that “[t]he coating material to seal the crack prior to
hot isostatic pressing, is chosen to match the superalloy substrate material
or it can be deliberately made to be different, so as to have enhanced
beneficial surface properties, or to allow easy removal of the coating after
hot isostatic pressing. The choice of coating must be compatible with the
superalloy part material.” Col. 5, ll. 20-26. White defines compatibility
as “some continuity or similarity of crystal structure, metallurgical
structure, or both, between the superalloy article and the repair of the
defect by diffusion healing from the coated material.” White further
states that “compatibility” implies that the superalloy material and the
coating material do not adversely affect each other. Col. 5, ll. 26-32.
6) According to White, the coating thickness should be sufficient to
be diffusion bonded by hot isostatic pressing (“HIP”) and seal the crack.
Generally, the thickness is about 0.001 to 0.010 inches thick before HIP
diffusion bonding, preferably about 0.010 inches. Col. 5, ll. 32-35.
4
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