This present paper investigates the friction and wear properties of friction material developed by ‘Hot Powder Preform Forging’ technique. The conventional technique to manufacture Metallo-ceramic brake pads was suc...This present paper investigates the friction and wear properties of friction material developed by ‘Hot Powder Preform Forging’ technique. The conventional technique to manufacture Metallo-ceramic brake pads was successfully and economically tried to replace the above process. Compacting and sintering technology suffers from certain major limitations such as inadequate joining of friction element with backing plate, poor density levels achieved in friction element owing to limited application of pressure during compacting, poor thermal conductivity due to high levels of porosity in the product, poor strength due to segregation of the impurities along prior particle boundaries (PPB’s) and, wide variations in final characteristics due to large number of variables involved. In contrast to these limitations, the present technique can offer brake pads of much simpler chemistry but with improved performance on account of simultaneous application of pressure and temperature and with better control of variables. Fade and recovery studies were carried out on a Krauss machine tester following the Economic Commission for Europe Regulation for replacement brake linings (ECE R-90). μfade, μrecovery, μperformance, % age fade , % age recovery & temperature rise lie within the range for friction materials used for low duty applications. The mechanical properties of these materials were characterized using ASTM standards.展开更多
Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Haw...Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Hawaii, of particulate matter (PM) PM = 60, PM = 10, and PM = 2.5. In order to do a rock magnetic characterization we have performed low field susceptibility vs. temperature [k-T] experiments to determine the Curie points of small particles collected from exhaust pipes, as well as from brake pads of four different types of car engines using gasoline octane ratings of 87, 89, and 92. The Curie point determinations are very well defined and range from 292<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C through 393<span style="white-space:normal;"><span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span></span>C and up to 660<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C. In addition, we have conducted magnetic granulometry experiments on raw tobacco, burnt tobacco ashes, as well as on automotive engine exhaust, and brake pads in question. The results of the experiments show ferro and ferrimagnetic hysteresis loops with magnetic grain sizes ranging from superparamagnetic-multidomain [SP-MD], multidomain [MD] and pseudo-single domain [PSD] shown on the modified Day et al., diagram of <a href="#ref3">Dunlop (2002)</a>. Thus far, the results we have obtained from this pilot study are in agreement with other studies conducted from cigarette ashes from Bulgaria. Our results could be correlated to the traffic-related PM in Rome, Italy where the SP fraction mainly occurs as coating of MD particles originated by localized stress in the oxidized outer shell surrounding the un-oxidized core of magnetite-like grains. All these magnetic particles have been reported to be very harmful to our human bodies (i.e. brain, lungs, heart展开更多
文摘This present paper investigates the friction and wear properties of friction material developed by ‘Hot Powder Preform Forging’ technique. The conventional technique to manufacture Metallo-ceramic brake pads was successfully and economically tried to replace the above process. Compacting and sintering technology suffers from certain major limitations such as inadequate joining of friction element with backing plate, poor density levels achieved in friction element owing to limited application of pressure during compacting, poor thermal conductivity due to high levels of porosity in the product, poor strength due to segregation of the impurities along prior particle boundaries (PPB’s) and, wide variations in final characteristics due to large number of variables involved. In contrast to these limitations, the present technique can offer brake pads of much simpler chemistry but with improved performance on account of simultaneous application of pressure and temperature and with better control of variables. Fade and recovery studies were carried out on a Krauss machine tester following the Economic Commission for Europe Regulation for replacement brake linings (ECE R-90). μfade, μrecovery, μperformance, % age fade , % age recovery & temperature rise lie within the range for friction materials used for low duty applications. The mechanical properties of these materials were characterized using ASTM standards.
文摘Today, it is well known that small airborne particles are very harmful to human health. For the first time in Hawaii we have conducted an environmental pilot study of fine magnetic particles on the island of Oahu, Hawaii, of particulate matter (PM) PM = 60, PM = 10, and PM = 2.5. In order to do a rock magnetic characterization we have performed low field susceptibility vs. temperature [k-T] experiments to determine the Curie points of small particles collected from exhaust pipes, as well as from brake pads of four different types of car engines using gasoline octane ratings of 87, 89, and 92. The Curie point determinations are very well defined and range from 292<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C through 393<span style="white-space:normal;"><span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span></span>C and up to 660<span style="color:#4F4F4F;font-family:" font-size:14px;white-space:normal;background-color:#ffffff;"="">°</span>C. In addition, we have conducted magnetic granulometry experiments on raw tobacco, burnt tobacco ashes, as well as on automotive engine exhaust, and brake pads in question. The results of the experiments show ferro and ferrimagnetic hysteresis loops with magnetic grain sizes ranging from superparamagnetic-multidomain [SP-MD], multidomain [MD] and pseudo-single domain [PSD] shown on the modified Day et al., diagram of <a href="#ref3">Dunlop (2002)</a>. Thus far, the results we have obtained from this pilot study are in agreement with other studies conducted from cigarette ashes from Bulgaria. Our results could be correlated to the traffic-related PM in Rome, Italy where the SP fraction mainly occurs as coating of MD particles originated by localized stress in the oxidized outer shell surrounding the un-oxidized core of magnetite-like grains. All these magnetic particles have been reported to be very harmful to our human bodies (i.e. brain, lungs, heart
