Asbestos was added as an common ingredient to Brake Pads post-WWI, as car speeds began to increase, because research showed that its properties allowed it to absorb the heat (which can reach 500 °F) while still providing the friction necessary to stop a vehicle. However, as the serious health-related hazards of asbestos eventually started to become apparent, other materials had to be found. Asbestos brake pads have largely been replaced by non-asbestos organic (NAO) materials in first world countries. Today, brake pad materials are classified into one of four principal categories, as follows:
Non-metallic materials - these are made from a combination of various synthetic substances bonded into a composite, principally in the form of cellulose, aramid, PAN, and sintered glass. They are gentle on rotors, but produce a fair amount of dust, thus having a short service life.
Semi-metallic materials - synthetics mixed with varying proportions of flaked metals. These are harder than non-metallic pads, more fade-resistant and longer lasting, but at the cost of increased wear to the rotor/drum which then must be replaced sooner. They also require more actuating force than non-metallic pads in order to generate braking torque.
Fully metallic materials - these pads are used only in racing vehicles, and are composed of sintered steel without any synthetic additives. They are very long-lasting, but require more force to slow a vehicle while wearing off the rotors faster. They also tend to be very loud.
Ceramic materials - Composed of clay and porcelain bonded to copper flakes and filaments, these are a good compromise between the durability of the metal pads, grip and fade resistance of the synthetic variety. Their principal drawback, however, is that unlike the previous three types, despite the presence of the copper (which has a high thermal conductivity), ceramic pads generally do not dissipate heat well, which can eventually cause the pads or other components of the braking system to warp.However, because the ceramic materials causes the braking sound to be elevated beyond that of human hearing, they are exceptionally quiet.
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Nanjing Pukou Textile Factory Suddenly Fire Casualty Report Diesel Generator | Diesel Generator Price / 2012-07-23
About two o'clock this afternoon, near the entrance of the Pukou section of the Yangtze River Crossing Tunnel in Nanjing, a textile factory burst into flames and heavy smoke blew up.
According to eyewitnesses at the scene, the fire spread rapidly and the smoke was as high as tens of meters. There are no reports of casualties.
Ben Wang reporter will send back new reports at the scene of the accident.
15:10, more than 10 fire engines have arrived on the scene
At 15:10, Ben Wang reporters saw at the scene of the accident that more than 10 fire engines had arrived at the scene, and 120 vehicles had arrived at the scene. About 2-3 wounded people were sent to the hospital.
Another witness on the scene said that in the event of a fire, a factory worker inside the factory called for help on the second floor of the plant. The firefighters broke into the window and finally rescued him. This female worker, who has suffered more serious injuries, has now been sent to the hospital for treatment.
According to a textile worker at the site, the fire was caused by a short circuit in the distribution box lighting up the plastic foam in the factory.
15:30 At present, the fire has basically been controlled
At 15:30, the reporter saw at the scene that after a firefighter’s intense work, the fire has basically been controlled.
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