Airborne wear particles from passenger car disc brakes: A comparison of measurements from field tests, a disc brake assembly test stand, and a pin-on-disc machine

Passenger car disc brakes are a source of ultrafine, fine, and coarse particles. It is estimated that 21% of total traffic-related PM10 emissions in urban environments originate from airborne brake wear particles. Particle number emission factors are in the magnitude of 1010 km−1 wheel brake during real-world driving conditions. Due to the complexity of the tribological processes and the limited observability of the friction zone between brake disc and pad, the phenomena causing particle emission of disc brakes are only partially understood. To generate a basis for understanding the emission process and, based on this, to clarify which influencing variables have how much potential for reduction measures, one approach consists in the identification and quantification of influencing variables in the form of emission maps. The subject of this publication is the influence of disc brake temperature on ultrafine, fine, and coarse particle emissions, which was investigated with a systematic variation of temperature during single brake events on an enclosed brake dynamometer. The systematic variation of temperature was achieved by increasing or decreasing the disc temperature stepwise which leads to a triangular temperature variation. Two types of brake pads were used with the main distinction in its chemical composition being organic and inorganic binder materials. The critical disc brake temperature for the generation of ultrafine particles based on nucleation is at approximately 180 °C for pads with an organic binder and at approximately 240 °C for pads with inorganic binder materials. Number concentration during those nucleation events decreased for successive events, probably due to aging effects. PM10 emissions increased by factor 2 due to an increase in temperature from 80 °C to 160 °C. The influence of temperature could be only repeatable measured for disc brake temperatures below 180 °C. Above this temperature, the emission behavior was dependent on the temperature history, which indicates also a critical temperature for PM10 relevant emissions but not in an increasing rather than a decreasing manner.

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A Pin-on-Disc Study Focusing on How Different Load Levels Affect the Concentration and Size Distribution of Airborne Wear Particles from the Disc Brake Materials

Tribology Letters ◽

10.1007/s11249-012-9944-5 ◽

2012 ◽

Vol 46 (2) ◽

pp. 195-204 ◽

Cited By ~ 39

Author(s):

J. Wahlström ◽

L. Olander ◽

U. Olofsson

Keyword(s):

Size Distribution ◽

Disc Brake ◽

Wear Particles ◽

Pin On Disc

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Wear Induced Failure of Automotive Disc Brakes—A Case Study

Materials ◽

10.3390/ma12244214 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4214 ◽

Cited By ~ 3

Author(s):

Ali Mohammadnejad ◽

Abbas Bahrami ◽

Majid Goli ◽

Hossein Dehbashi Nia ◽

Peyman Taheri

Keyword(s):

Wear Mechanisms ◽

Optical Microscope ◽

Outer Edge ◽

Brake Disc ◽

Disc Brake ◽

Root Cause ◽

Disc Brakes ◽

Pin On Disc ◽

Radial Cracks ◽

Worn Surface

This paper investigated a failure in a ventilated disc brake in an automobile. The failed brake disc had been in service for approximately 10 years. The observed failure was in the form of radial cracks that appeared to have initiated at the outer edge of the disc brake. The cracks were rather straight with no branching. Optical microscope, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) were used to study the microstructure of the failed disc. Vickers microhardness test was also used to evaluate the hardness of the samples. Results showed that the root cause of crack formation, in this case, was related to the excessive wear in the brake disc. Different wear mechanisms, namely abrasive and adhesive wear, were recognized in the failed specimen. Moreover, the worn surface in some areas was covered with fine oxide particles. These particles appeared to have a significant contribution toward abrasion. To further understand the wear mechanisms, pin-on-disc experiments were also conducted on the samples. Results of the pin-on-disc experiments were compared and correlated to the results obtained from the failed brake disc.

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A disc brake test stand for measurement of airborne wear particles

Lubrication Science ◽

10.1002/ls.87 ◽

2009 ◽

Vol 21 (6) ◽

pp. 241-252 ◽

Cited By ~ 15

Author(s):

Jens Wahlström ◽

Anders Söderberg ◽

Lars Olander ◽

Ulf Olofsson

Keyword(s):

Test Stand ◽

Disc Brake ◽

Wear Particles

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Braking performance of a novel frictional-magnetic compound disc brake for automobiles

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407018791056 ◽

2018 ◽

Vol 233 (10) ◽

pp. 2443-2454 ◽

Cited By ~ 1

Author(s):

Yan Yin ◽

Jiusheng Bao ◽

Jinge Liu ◽

Chaoxun Guo ◽

Tonggang Liu ◽

...

Keyword(s):

Magnetic Field ◽

Temperature Rise ◽

Friction Material ◽

Maximum Temperature ◽

Interface Temperature ◽

Disc Brake ◽

Braking Performance ◽

Maximum Temperature Rise ◽

Disc Brakes ◽

Braking Torque

Disc brakes have been applied in various automobiles widely and their braking performance has vitally important effects on the safe operation of automobiles. Although numerous researches have been conducted to find out the influential law and mechanism of working condition parameters like braking pressure, initial braking speed, and interface temperature on braking performance of disc brakes, the influence of magnetic field is seldom taken into consideration. In this paper, based on the novel automotive frictional-magnetic compound disc brake, the influential law of magnetic field on braking performance was investigated deeply. First, braking simulation tests of disc brakes were carried out, and then dynamic variation laws and mechanisms of braking torque and interface temperature were discussed. Furthermore, some parameters including average braking torque, trend coefficient and fluctuation coefficient of braking torque, average temperature, maximum temperature rise, and the time corresponding to the maximum temperature rise were extracted to characterize the braking performance of disc brakes. Finally, the influential law and mechanism of excitation voltage on braking performance were analyzed through braking simulation tests and surface topography analysis of friction material. It is concluded that the performance of frictional-magnetic compound disc brake is prior to common brake. Magnetic field is greatly beneficial for improving the braking performance of frictional-magnetic compound disc brake.

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