PCCB Material ???
11-09-2005, 05:02 PM
#1
PCCB Material ???
Perhaps this is a really geeky question, but anyone know what the PCCB rotors are made from.???
I saw the Elise had some Aluminum:Silicon Carbide MMC rotors.
Some article about Yamaha bikes talked of Carbon fibre reinforced materials (Aulminum infiltrated ?)
Being an Engineer i would just like to satisfy my curiosity on this, and know if its the same Al:SiC that im working with..
Thanks
I saw the Elise had some Aluminum:Silicon Carbide MMC rotors.
Some article about Yamaha bikes talked of Carbon fibre reinforced materials (Aulminum infiltrated ?)
Being an Engineer i would just like to satisfy my curiosity on this, and know if its the same Al:SiC that im working with..
Thanks
11-09-2005, 06:04 PM
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C:SiC. It is a silicon impregnated C/C (Carbon/Carbon) composite. That is, a porous carbon fiber/carbon matrix precursor body is impregnated with molten silicon, reacting for form SiC. The final structure should have a matrix phase of SiC providing high heat capacity, high temperature properties, hardness, and wear resistance (SiC has a Mohs hardness between 9 and 10, compared to a 10 for diamond).
Similar technology is used in the context of high temperature semiconductor processing components, such as wafer boats, paddles and process tubes, which rely on a silicon infiltration process to form siliconized silicon carbide having stellar high temperature properties.
The rotors are made by the SGL Carbon Group for Porsche.
The Elise no longer uses composite rotors. The company that used to make them for Lotus went bankrupt, Lanxide based out of Delaware. That rotor was entirely different, and was formed through an oxidation process of Al. Lanxide went belly up and was sued by its shareholders IIRC.
As you can tell, I'm a geek too.
Similar technology is used in the context of high temperature semiconductor processing components, such as wafer boats, paddles and process tubes, which rely on a silicon infiltration process to form siliconized silicon carbide having stellar high temperature properties.
The rotors are made by the SGL Carbon Group for Porsche.
The Elise no longer uses composite rotors. The company that used to make them for Lotus went bankrupt, Lanxide based out of Delaware. That rotor was entirely different, and was formed through an oxidation process of Al. Lanxide went belly up and was sued by its shareholders IIRC.
As you can tell, I'm a geek too.
11-09-2005, 07:34 PM
#3
I did some reading on this on the net and discovered that not all cermaic rotors/disks are alike in composition. They contain various quantatities of carbon and Si depending on the precise properties they are aiming for.
11-09-2005, 09:55 PM
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11-09-2005, 09:57 PM
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From the Christophorus #311 Article....
At the core of a state-of-the-art automotive brake is a disk. In the Porsche Ceramic Composite Brake (PCCB), this brake disk is exceptionally rugged and effective. Now the second generation has been rolled out.
Donatus Neudeck, manager of the Department of Brakes, Hydraulics and Actuation Systems at the Porsche Development Center in Weissach, is pleased with recent advances in deceleration. "Since 2001, we've been producing the ceramic brake on a fairly large scale. And thanks to our rigorous development program, we're already selling the second generation," he reports proudly. When it comes to brakes, making what's already excellent even better is often a matter of incremental advances. Accordingly, the specification for the Porsche Ceramic Composite Brake (PCCB) included just three objectives: improved cooling, reduced wear, and increased dimensional stability of the disk.
So what's actually new in the new-generation brake? To illustrate, Neudeck places two 350-millimeter-diameter brake disks side by side on his desk-one old, one new. That almost settles the issue right then and there. While the 20 air outlets in the first generation are oblong, the new ones are square. And there are twice as many outlets now as before. The perforation pattern on the braking surface has been changed as well. It used to be regular. Not it's more random. Neudeck explains that the reason is on the inside as he retrieves two cut-away models from a cabinet. While the cooling channels in the first generation follow an involute curve, the new channels are based on an Arcus design. This is an entirely new cooling channel geometry. It allows the cooling air to enter with a minimum of friction and accelerates it to a high speed as it exits. The brake disk becomes a turbine- to maximize airflow at any engine speed. At 200 km/h, an air flow of about 250 liters per second is conducted efficiently through these channels along the internal surface of the disk. The result: The new design has improved efficiency by 20 percent.
Now Neudeck rearranges the "show-and-tell" on his desk. He shoves the two cut-away models aside and puts a complete brake disk in their place. Then he wipes some grime off his hands with his handkerchief. "This disk was installed in one of our test vehicles and has traveled a total distance of 300,000 kilometers (186,300 miles)." Any visible wear? None. This disk, which had been mounted on the front axle, is still 34 millimeters thick, just like when it was new. "This disk doesn't really look so out of the ordinary. But then, it wasn't supposed to."
Abrasion resistance has been further improved. "We're using thicker carbon fibers now," notes Neudeck. Actually, they're fiber bundles. Three thousand fibers were previously used to form such a bundle; the new generation has 400,000! A company located near Augsburg has proven an effective partner in manufacturing PCCB disks. As a first step, carbon fibers are produced from the plastic polyacrylonitrite (PAN). These fibers are then heated and carbonized in a two-phase process-first in an oxidizing atmosphere, then with the air excluded. Then the carbon fibers are ground up and saturated in a synthetic resin to produce a sticky putty that can be shaped.
In the new brake disk, each carbon fiber bundle consists of 400,000 fibers (compared to 3000 in prior models).
"To create the new shape of the cooling channels, we use a 'lost core' that burns up without leaving a residue," Neudeck explains. The polymer components are allowed to harden in a heated press. The intermediate result is a carbon-fiber reinforced blank. The blank is heated to nearly 1000 degrees Celsius (1830 degrees Fahrenheit) in a nitrogen-rich atmosphere to convert it into pure carbon. In the next step, the disk is heated to about 1420 Grad Celsius (2590 degrees Fahrenheit) and infiltrated with silicon. The disk absorbs the molten silicon like a sponge. When the disk cools, silicon carbide forms, which is almost as hard as diamond. "The new fiber technology causes even more silicon carbide to form on the surface, which results in even greater resistance to wear and abrasion," Neudeck explains.
The "lost-core" process can be used to create more complex geometries than had been possible with previous production processes, which used to create two half-disks that were then joined and bonded together before being siliconized. At the same time, the new process can accommodate larger production quantities. In the future, the PCCB will therefore be available not only in the Carrera GT and the Turbo, but also in both models of the 911 Carrera and in the Boxster S.
The PCCB has reduced the weight of the braking system for the new 911 by 14 kilograms (31Ibs.).
Though Neudeck's team has just completed developing the second generation PCCB, its members are eagerly looking forward to further developments. "Since this is still a relatively new subject, we're learning by leaps and bounds," notes the team leader. One improvement they've achieved is the lower weight. In the new 911 Carrera, the brake disks weigh only half of what they used to weigh, and the complete braking system weighs 14 kilograms (3.1lbs.) less. "Lightweight materials-mostly aluminum alloys-are being used throughout the chassis," notes Neudeck. But not one of those engineering improvements has trimmed off as much weight as have the lightweight but rugged brake disks. According to Neudeck, the reduction in unsprung mass of the ceramic brake not only provides a more comfortable ride, but also improves driving dynamics. And in a Porsche, that's certainly an important advantage.
Before removing the demo disks from his desk, Neubeck delivers his final point: "Today the ceramic brake is still a high-end component. But it's technically so superior that we're working hard to make it available for more general use."
At the core of a state-of-the-art automotive brake is a disk. In the Porsche Ceramic Composite Brake (PCCB), this brake disk is exceptionally rugged and effective. Now the second generation has been rolled out.
Donatus Neudeck, manager of the Department of Brakes, Hydraulics and Actuation Systems at the Porsche Development Center in Weissach, is pleased with recent advances in deceleration. "Since 2001, we've been producing the ceramic brake on a fairly large scale. And thanks to our rigorous development program, we're already selling the second generation," he reports proudly. When it comes to brakes, making what's already excellent even better is often a matter of incremental advances. Accordingly, the specification for the Porsche Ceramic Composite Brake (PCCB) included just three objectives: improved cooling, reduced wear, and increased dimensional stability of the disk.
So what's actually new in the new-generation brake? To illustrate, Neudeck places two 350-millimeter-diameter brake disks side by side on his desk-one old, one new. That almost settles the issue right then and there. While the 20 air outlets in the first generation are oblong, the new ones are square. And there are twice as many outlets now as before. The perforation pattern on the braking surface has been changed as well. It used to be regular. Not it's more random. Neudeck explains that the reason is on the inside as he retrieves two cut-away models from a cabinet. While the cooling channels in the first generation follow an involute curve, the new channels are based on an Arcus design. This is an entirely new cooling channel geometry. It allows the cooling air to enter with a minimum of friction and accelerates it to a high speed as it exits. The brake disk becomes a turbine- to maximize airflow at any engine speed. At 200 km/h, an air flow of about 250 liters per second is conducted efficiently through these channels along the internal surface of the disk. The result: The new design has improved efficiency by 20 percent.
Now Neudeck rearranges the "show-and-tell" on his desk. He shoves the two cut-away models aside and puts a complete brake disk in their place. Then he wipes some grime off his hands with his handkerchief. "This disk was installed in one of our test vehicles and has traveled a total distance of 300,000 kilometers (186,300 miles)." Any visible wear? None. This disk, which had been mounted on the front axle, is still 34 millimeters thick, just like when it was new. "This disk doesn't really look so out of the ordinary. But then, it wasn't supposed to."
Abrasion resistance has been further improved. "We're using thicker carbon fibers now," notes Neudeck. Actually, they're fiber bundles. Three thousand fibers were previously used to form such a bundle; the new generation has 400,000! A company located near Augsburg has proven an effective partner in manufacturing PCCB disks. As a first step, carbon fibers are produced from the plastic polyacrylonitrite (PAN). These fibers are then heated and carbonized in a two-phase process-first in an oxidizing atmosphere, then with the air excluded. Then the carbon fibers are ground up and saturated in a synthetic resin to produce a sticky putty that can be shaped.
In the new brake disk, each carbon fiber bundle consists of 400,000 fibers (compared to 3000 in prior models).
"To create the new shape of the cooling channels, we use a 'lost core' that burns up without leaving a residue," Neudeck explains. The polymer components are allowed to harden in a heated press. The intermediate result is a carbon-fiber reinforced blank. The blank is heated to nearly 1000 degrees Celsius (1830 degrees Fahrenheit) in a nitrogen-rich atmosphere to convert it into pure carbon. In the next step, the disk is heated to about 1420 Grad Celsius (2590 degrees Fahrenheit) and infiltrated with silicon. The disk absorbs the molten silicon like a sponge. When the disk cools, silicon carbide forms, which is almost as hard as diamond. "The new fiber technology causes even more silicon carbide to form on the surface, which results in even greater resistance to wear and abrasion," Neudeck explains.
The "lost-core" process can be used to create more complex geometries than had been possible with previous production processes, which used to create two half-disks that were then joined and bonded together before being siliconized. At the same time, the new process can accommodate larger production quantities. In the future, the PCCB will therefore be available not only in the Carrera GT and the Turbo, but also in both models of the 911 Carrera and in the Boxster S.
The PCCB has reduced the weight of the braking system for the new 911 by 14 kilograms (31Ibs.).
Though Neudeck's team has just completed developing the second generation PCCB, its members are eagerly looking forward to further developments. "Since this is still a relatively new subject, we're learning by leaps and bounds," notes the team leader. One improvement they've achieved is the lower weight. In the new 911 Carrera, the brake disks weigh only half of what they used to weigh, and the complete braking system weighs 14 kilograms (3.1lbs.) less. "Lightweight materials-mostly aluminum alloys-are being used throughout the chassis," notes Neudeck. But not one of those engineering improvements has trimmed off as much weight as have the lightweight but rugged brake disks. According to Neudeck, the reduction in unsprung mass of the ceramic brake not only provides a more comfortable ride, but also improves driving dynamics. And in a Porsche, that's certainly an important advantage.
Before removing the demo disks from his desk, Neubeck delivers his final point: "Today the ceramic brake is still a high-end component. But it's technically so superior that we're working hard to make it available for more general use."
