Appeal No. 2007-1530
Application 10/095,112
While attempting to produce a substrate that is lower in weight, higher
in electrical conductivity, tougher and harder than its aluminum
predecessors, the Al—B—C ceramic is excellent. Its density is lower
than the others, its electrical conductivity nearly rivals pure metallic
aluminum, its stiffness is excellent, its fracture toughness is very
good, and its hardness is more than satisfactory. As one can see, all
the properties needed for a substrate are easily met or exceeded by the
Al—B—C composite material.
(Col. 8, ll. 22-29.) Thus, the electrical conductivity of the Al—B—C ceramic is
described as “nearly rival[ling] pure metallic aluminum” (id.) even though
aluminum’s conductivity exceeds that of the Al—B—C ceramic by more than an
order of magnitude. High electrical conductivity and low density are also among
the properties mentioned in the following summary of the properties of Pyzik’s
composites:
Accordingly, the present invention provides hard drive disk
substrates, methods of making same, and materials made therefrom,
wherein the material has a high hardness, a high wear resistance, a
high fracture toughness, a high damping capability, a low density, and
a high specific stiffness and is electrically conductive. In addition, the
material forming the disk substrates exhibits unique combinations of
properties, such as high stiffness and high toughness, high hardness
and high strength, and high stiffness and high damping capability.
Col. 13, ll. 3-12 (emphasis added).
Pyzik’s composite material is also capable of being coated with a layer of
metal, such as copper: “If a sub-surface (below the magnetic media layer) coating
is desirable, the sub-surface material may be metal (e.g., chromium, nickel, cobalt,
silicon, aluminum, copper, titanium, or magnesium), metal alloy, metal oxide,
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