HPM@SU-AI@sri-unix.UUCP (08/28/83)
From: Hans Moravec <HPM@SU-AI>
n102 2020 21 Aug 83
By Robert Cooke
(c) 1983 Boston Globe (Independent Press Service)
Propped against the wall in Jim Hannoosh's office is a dark gray
slab of sparkly material that represents tomorrow.
''That,'' Hannoosh said, pointing to the slab, ''is state of the
art'' in modern ceramics. It's made of silicon nitride, which,
through research, has been made into a 21st Century material so
strong, so heat-and-corrosion resistant it makes steel seem a
weakling.
On Hannoosh's desk at the Norton Co. in Worcester, Mass., there's
also a handful of small ball bearings. These, too, are made of
silicon nitride, and they're capable of standing three times more
pressure and two times more heat than most steel bearings.
Such products are just the beginning. In modern research
laboratories around the world, scientists have developing a new
family of exotic ceramics that are opening a new era of super-strong,
ultra-hard, heat-resistant materials for high technology.
Other high technology ceramic materials include aluminum oxide,
zirconium oxide and silicon carbide, each of which has its own set of
useful properties.
In time, these new ceramics are expected to replace rare and
expensive metals in many applications, especially where heat
resistance, hardness and durability are critical factors. In diesel
engines, for instance, or in gas turbines.
Because of recent progress, and increasing demand for ultra-durable
materials, says Prof. G.B. Kenney, at MIT, high technology ceramics
have now reached a threshhold, ''a leverage point ... where you make
a major or quantum jump with a new materials technology, and a lot of
(other) new technologies open up.''
Thus, observers expect high technology ceramics use to increase
dramatically in the electronics industry, in gas turbines, jet
engines, in automotive engines and elsewhere.
As should be expected, the Japanese are out front in the race to
take command of this hot new technology. As reported by MIT
Professors H. Kent Bowen and Kenney, Japan's aggressive new emphasis
on ceramics ''represents a bold initiative to achieve technological
and market leadership'' in the field.
They estimated the current worldwide market for high technology
ceramics is around $4.25 billion. Half of it is now being met by
Japanese companies, with sales of $2 billion in 1980.
''Fine ceramics (high performance ceramics) are expected to
significantly influence the future of electronics, machining
operations, automotive and utility power plants and processing and
manufacturing system automation.''
In fact, say Bowen and Kenney, half of the high-technology ceramics
now marketed worldwide are made by the Japanese. And on top of that,
the Japanese government and industry have teamed to support an
ambitious, richly endowed research program that may make Japan
unbeatable in high performance ceramics.
As Japan has pushed into the lead, they added, ''Great Britain, a
traditional leader in the development of ceramics, has lost its
advantage ... . The current challenge for ceramic industry leadership
comes from Japan, where ceramics production and technology are
flourishing.''
Hannoosh, a scientist involved the Norton Co.'s expanding ceramics
research effort, added that the United States ''is actively competing
with them. In some areas we're behind. But in other areas we're
ahead.''
And, he said, one should remember that ''the United States has been
the benchmark against which other work has been compared.''
Recently, Hannoosh said, several U.S. agencies ''have begun
increasing funding in this area, in part because of the increased
spending in Japan and Europe, but also because this is recognized as
a technology that the United States needs. And we do have the people,
the materials science techniques and the resources to make it work.''
In addition, he said, ''Norton considers itself a leader in this
field of high performance ceramics, and we plan to be a key player in
the future in this area.''
Looking ahead, Hannoosh said ''there are going to be applications
for these materials where they haven't been used before,'' since
their properties suit them for use in high performance machinery as
bearings, as blades, bushings and other critical parts. This is
especially true, he said, for the ''hot'' zones in new machinery
where components must stand up reliably to extremes of heat and
pressure.
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nyt-08-21-83 2310edt
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n104 2041 21 Aug 83
BC-CERAMICS-1stadd-08-22
X X X HEAT AND PRESSURE.
At present, many such parts - especially those made for use in
extra-hot environments - are made from expensive metals, the
so-called super-alloys. These alloys require large amounts of metals
such as cobalt and chromium, which are not abundant in the United
States.
Ceramics, on the other hand, are made from common and plentiful
elements such as silicon, nitrogen, carbon and zirconium, which are
abundant.
According to researchers, some of the emerging uses for the new
ceramics include:
- The ceramic diesel engine, already built and being tested in
separate programs by the U.S. Army and Japanese industrial firms.
Ceramic engine parts are so heat-resistant they can operate at very
high temperatures. Thus cooling equipment can be minimized, or even
eliminated, savi ght. As a result of less weight and higher
''burn'' temperatures, fuel efficiency is boosted by as much as 50
percent.
- Ceramic armor, made of boron carbide backed by Kevlar, is formed
into crashworthy and bullet-resistant seats for military helicopters.
A Norton Co. official, Richard Alliegro, said the seats provide
protection at 35 percent of the weight of comparable steel armor.
- In energy production systems, ceramic turbine blades allow hotter,
more complete combustion. Researchers expect fuel savings of up to 15
percent.
- Inclusion of high technology ceramics in metals, such as aluminum,
to increase stiffness without increasing weight. The military is
especially interested in such ''metal matrix'' materials for use in
helicopters, tanks, bridges and other applications where weight is
important.
Ceramics, of course, are among the oldest materials used by humans.
The use of ceramics dates back thousands of years to the oldest clay
bowls, fashioned from mud and baked in the hot flames of a campfire.
But these new ceramics are a far cry from the bowls and basins
thrown on a potter's wheel, very different indeed from the familiar
cups, saucers and toilet bowls that also are known as ceramics.
Unfortunately, most ceramic materials, including some of the high
technology ceramics, share a common problem, brittleness, the
tendency to shatter.
In other words, ceramic materials tend to be hard, and they can be
strong, but they're limited by not being very tough.
Norton's vice president for high performance ceramics, Robert A.
Rowse, noted that ''The problem has been reliability. When they
(ceramic parts) fail, they fail catastrophically.''
As a result, engineers designing machinery tend to avoid using
ceramics in rapidly rotating parts.
''So,'' Rowse said, research is ''aimed now at improving strength,
and to avoid catastrophic failure.''
In looking at current research and development, Hannoosh said the
most exciting areas are:
- Ceramic matrix composite materials, in which ceramic fibers are
embedded in a ceramic structures to supply toughness, overcoming the
difficult problem of brittleness.
- Transformation-toughened materials, in which the interior
structure of a ceramic part is toughened by controlled application of
heat, similar to the heat-treating of metals.
- Hot isostatic pressing, in which intricately shaped ceramic parts
can be toughened under special conditions in very high-pressure
furnaces.
As for the ceramic diesel engine, the Cummins Engine Co., working
with the U.S. Army's Tank and Automotive Command, has developed a
five-ton truck powered by an uncooled engine that has ceramic-lined
combustion chambers.
According to Robert Katz, chief of the ceramic research division of
AMMRAC (Army Materials and Mechanics Research Center) in Watertown,
on a 500-mile trip the truck achieved about 9 miles per gallon, a 50
percent improvement over a conventional diesel engine.
Also, the Kyocera Corp., in Kyoto, Japan, has built an automobile
powered by an uncooled diesel engine, which is made substantially of
silicon nitride. Company officials estimate the fuel savings will be
close to 30 percent.
END
nyt-08-21-83 2331edt
***************sdb@shark.UUCP (Steven Den Beste) (08/30/83)
I don't know much about chemical bonds, but it seems to me that silicon nitride should be extremely explosive. Obviously it isn't if they can line the cylinders of a diesel engine with it...