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1969
Commercial Introduction of Borazon* CBN – Cubic
Boron Nitride
New
Workpiece Materials Challenge GE Scientists
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| Borazon
CBN 1000 |
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| Borazon
CBN Type I |
CBN is not
found in nature. GE scientists invented it in 1957,
when they were conducting experiments to produce a substance
harder than diamond. The scientists substituted graphite
with hexagonal boron nitride, whose arrangement of atoms
is similar to graphite, and then used a catalyst of
alkali metals and nitrides of lithium, calcium and magnesium
in the high pressure/high temperature diamond manufacturing
process. The CBN crystals that were created were not
harder than diamond and were, in fact, not as good as
diamond for cutting cemented tungsten carbide. However,
other uses awaited this material.
The emergence of hardened steel, stainless steel, and
a wide variety of superalloys created a need for a new
abrasive capable of grinding these workpiece materials.
Diamond is not effective grinding steel because its
carbon solubility is high in ferrous materials at the
high temperatures and pressures normally occurring in
the grinding and machining processes. When this carbon
solubility problem was discovered, scientists already
had a noncarbon superabrasive product on the shelf.
Cubic boron nitride (CBN) makes it possible to manufacture
grinding wheels that are harder, longer lasting, quicker,
and that produce a better finished product than aluminum
oxide.
Like manufactured diamond, CBN production can be manipulated
to meet the need for specific applications. It can be
produced either as monocrystals, blocky-shaped large
crystals or strongly bonded microcrystalline, micrometer-size
grits, that are irregular in shape. Cubic boron nitride
was commercially introduced by GE in 1969 as Borazon*
CBN, a superabrasive for grinding hardened steel. It
was quickly proven to be far superior to conventional
aluminum oxide abrasives. Today there is a family of
Borazon* CBN products, each tailored to a specific bond
system and/or mode of material removal for grinding
tool and die steels, hardened steels and superalloys.
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