Ceramic brake discs? With a special
combination of carbons and silicon developed by the DaimlerChrysler researchers, brake
discs can now be mass-produced from carbon-fiber-reinforced ceramics. FR ceramics retain
their heat resistance up to 2,000°C; only in excess of this temperature do they lose
their dimensional stability. They do not rust under high oxygen concentration, and their
low density makes them three times as light as steel -- in the case of a high-speed ICE
train with 36 brake discs, the weight savings could amount to six tons. As brake discs,
they do not wear even under constant use. Heavily-laden commercial vehicles can be braked
safely over long distances without having to undergo brake maintenance, dispensing with
the need for expensive maintenance. The brake disks are produced by first compressing
short carbon fibers, carbon powder and rosin, then sintering the mix at 1,000°C. In the
furnace, a stable framework of carbon fibers in a carbon matrix is created. Once cooled,
this material can be ground down like wood, and the brake disc obtains its final shape.
Together with silicon, the disc blank goes into the furnace a second time. Pores in the
carbon framework absorb the silicon melt like a sponge, creating the ceramic material when
the matrix carbon combines with the liquid silicon.
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The last few years have brought several advances in self-contained
power systems, with an April announcement of one company's intent to have fuel
cell-powered buses on the road by 2002. Another company, Metallic Power of Carlsbad, CA,
has been demonstrating their prototype zinc/air fuel cell in small utility carts, which
will be their first target market. Power in the cell comes from combining 1mm spheres of
zinc with airborne oxygen in the presence of an electrolyte. The resultant reaction
produces electricity and zinc oxide, a safe byproduct commonly used in skin creams and
sunblocks. When the cell runs low on power output, it is inserted into a recycling unit
that uses standard household current to convert the zinc oxide back into zinc, releasing
oxygen back into the air. Thus, the entire process would be a closed-loop system, with
nothing to add and nothing to discard. Production versions of the recycling unit will
provide cell turnaround times of less than six minutes. In comparison with a lead-acid
battery, the zinc fuel cell has up to seven times more energy per pound and three times
the energy per volume. Where lead-acid batteries have a typical life of two years under
heavy use (as in utility carts), the zinc/air fuel cell may last five to ten years,
according to Metallic Power.
Ceramic brake discs? With a special
combination of carbons and silicon developed by the DaimlerChrysler researchers, brake
discs can now be mass-produced from carbon-fiber-reinforced ceramics. FR ceramics retain
their heat resistance up to 2,000°C; only in excess of this temperature do they lose
their dimensional stability. They do not rust under high oxygen concentration, and their
low density makes them three times as light as steel -- in the case of a high-speed ICE
train with 36 brake discs, the weight savings could amount to six tons. As brake discs,
they do not wear even under constant use. Heavily-laden commercial vehicles can be braked
safely over long distances without having to undergo brake maintenance, dispensing with
the need for expensive maintenance. The brake disks are produced by first compressing
short carbon fibers, carbon powder and rosin, then sintering the mix at 1,000°C. In the
furnace, a stable framework of carbon fibers in a carbon matrix is created. Once cooled,
this material can be ground down like wood, and the brake disc obtains its final shape.
Together with silicon, the disc blank goes into the furnace a second time. Pores in the
carbon framework absorb the silicon melt like a sponge, creating the ceramic material when
the matrix carbon combines with the liquid silicon.
The last few years have brought several advances in self-contained
power systems, with an April announcement of one company's intent to have fuel
cell-powered buses on the road by 2002. Another company, Metallic Power of Carlsbad, CA,
has been demonstrating their prototype zinc/air fuel cell in small utility carts, which
will be their first target market. Power in the cell comes from combining 1mm spheres of
zinc with airborne oxygen in the presence of an electrolyte. The resultant reaction
produces electricity and zinc oxide, a safe byproduct commonly used in skin creams and
sunblocks. When the cell runs low on power output, it is inserted into a recycling unit
that uses standard household current to convert the zinc oxide back into zinc, releasing
oxygen back into the air. Thus, the entire process would be a closed-loop system, with
nothing to add and nothing to discard. Production versions of the recycling unit will
provide cell turnaround times of less than six minutes. In comparison with a lead-acid
battery, the zinc fuel cell has up to seven times more energy per pound and three times
the energy per volume. Where lead-acid batteries have a typical life of two years under
heavy use (as in utility carts), the zinc/air fuel cell may last five to ten years,
according to Metallic Power.