Mr. Shotaro Imai, ADVICS CO.,LTD., JAPAN

Mr. Katsuya Okayama, ADVICS CO.,LTD., JAPAN

Mr. Koji Sugimoto, ADVICS CO.,LTD., JAPAN

Ms. Noriko Matsunaga, ADVICS CO.,LTD., JAPAN

Brake wear debris and its contents have been matters of concern due to their impacts on the human body and the environment, which has led to many studies being done in the brake industry.

In North America, copper is a prime example of brake wear debris impacting the environment when it’s exhausted to the atmosphere. The regulation of copper content in brake pads for new cars has been enacted and has led to the development of copper free friction materials which are used in the market today.

In Europe, micro particles such as PM2.5 and PM10 contained in the brake wear debris, which are also called BPE (brake particle emissions), are considered to affect human health and air pollution. As regulatory activities have accelerated, so has the work towards establishing measuring methods of BPE.

As a brake supplier, fundamental research is necessary for understanding characteristics of BPE and reducing the amount of BPE for each type of friction material. As the first step of the research, BPE characteristics were investigated for various friction materials, such as Low Steel, Non Asbestos Organic, and Cu-Free Non Asbestos Organic. In addition, a hard coated rotor was also prototyped and investigated.

In this study, a brake corner for a compact passenger car was used for testing.

Particulate mass (PM2.5 and PM10) were obtained by a measurement system in accordance with JASO C470 (established in 2020). Also, the CPC (condensation particle counter) device was added to this system in order to measure the particulate number (PN) which was proposed in the WP29/GRPE/PMP/TF2 document.

As a result, there were significant differences in the amount of BPE among the friction materials tested. The results also show good correlation between the amount of BPE and wear mass of the pad and rotor. In addition, it is suggested that PM2.5 account for 9-18% of wear mass, PM10 for 31-43% in this test condition.

Mr. Masato Furuta, ADVICS CO.,LTD., JAPAN

Mr. Yukio Nishizawa, ADVICS CO.,LTD., JAPAN

Mr. Masaru Yagihashi, ADVICS CO.,LTD., JAPAN

Mr. Masayoshi Fuji, Nagoya Institute of Technology, JAPAN

In the automotive industry, regulations concerning fuel economy are expected to be reinforced to address environmental and energy-related issues. Therefore, demands for products with reduced size and weight are expected to increase. Furthermore, measures for reducing CO2 emissions in the manufacturing process will also be required to contribute to a low-carbon society. However, conventional brake pads, which contain organics in the blended materials, are not beneficial to reducing the size and weight of brake pads because organic materials tend to decompose during high-temperature friction, leading to reduction in frictional performance. Furthermore, the heating process, which is a source of CO2 emissions, cannot be eliminated in the manufacturing process, because thermosetting resins are used as a binder.

Given the above issues, this research focused on a ceramics technology that utilizes mechanochemical reactions to achieve solidification without firing (non-firing ceramics). By using the non-firing ceramics as a binder, it is expected that high temperature decomposition can be prevented and frictional performance can be improved. It is also expected that CO2 emissions can be reduced, as this technology is a solidification method that proceeds at low temperatures and completes in a short time; this implies that firing will not be required in the manufacturing process.

We combined the binder (non-firing ceramics) with abrasive materials, lubricants, inorganic fillers, and reinforcement fibers, and fabricated brake pads. Results showed that the fabricated brake pads had demonstrated good frictional performance under high temperature and sufficient strength. We consider that non-firing ceramics can be applied to brake pads.