Recently, the evaluation meeting for domestic powder metallurgy aluminum matrix composite brake disc passenger transport operation, hosted by the China Urban Rail Transit Association, was held in Guangzhou. Led by the National Engineering Research Center for Safety and Operation and Maintenance of Urban Rail Transit System of Guangzhou Metro Group Co., Ltd. and jointly implemented by Hunan Xiangtou Light Material Technology Co., Ltd. (hereinafter referred to as "Xiangtou Light Material"), CRRC Zhuzhou Locomotive Co., Ltd. and Knorr Bremse Vehicle Equipment (Suzhou) Co., Ltd., the project of powder metallurgy aluminum matrix composite brake disc successfully passed the review.
The meeting invited 9 urban rail transit industry experts from Shanghai Shentong Metro Group Metro Group Co., Ltd., Shenzhen Metro Metro Group Co., Ltd., Qingdao Metro Group Co., Ltd., CRRC Brake System Co., Ltd., China Academy of Railway Sciences Group Co., Ltd., Tongji University, Central South University and other units to form an expert group to review the project. The project achievements have broken the long-term monopoly of foreign countries in the field of high-speed aluminum based brake discs, solved the problem of high maintenance costs for imported aluminum based brake discs, and achieved a historical breakthrough in free maintenance throughout the entire life cycle of brake discs. The expert group unanimously agreed that the project passed the review, and suggested that the batch loading of powder metallurgy aluminum based composite brake discs should be expanded as soon as possible. This move means that Xiangtou Light Material Powder Metallurgy Aluminum Matrix Composite Brake Discs are about to promote large-scale installation and application, promoting the comprehensive entry of China's urban rail transit equipment into a new era of greening and localization.

The brake discs applied to a train of Guangzhou Metro Line 21 this time are the first batch of aluminum matrix composite brake discs prepared by powder metallurgy near net forming process in China. As of June 10, 2023, the train has carried more than 60000 kilometers of passengers. Under the current operating mileage, the maximum wear of aluminum based brake discs is 0.0073mm/10000 kilometers. According to the maximum wear, the service life of the brake disc is 6.84 million km. According to the annual operating mileage of Guangzhou Metro Line 21, the service life of the brake disc can reach more than 30 years.
The measured data shows that the weight of aluminum based brake discs with dimensions 640/350-21 is reduced by about 60% compared to traditional cast iron discs. The reduction of vehicle axle load and unsprung rotational mass can reduce the impact on the track during vehicle operation, while a smaller rotational mass can reduce vehicle acceleration energy consumption, which is particularly significant for subway systems with frequent braking and acceleration. A typical 120km/h subway train is expected to save 50000 kWh of electricity per year, meeting the green and low-carbon development needs of the rail transit industry.
The powder metallurgy aluminum matrix composite brake disc adopts advanced aluminum matrix ceramic composite materials independently developed by Xiangtou Light Materials, and integrates advanced innovative technology achievements from upstream and downstream companies such as industry leading enterprises in braking systems, international first-class vehicle equipment, and subway operation enterprises. The overall technology has reached the international advanced level. The successful application of this product in Guangzhou Metro Line 21 also marks that the project has achieved phased results. In the next stage, Xiangtou Light Material will continue to strengthen independent innovation and forward-looking research and development, promote the further application of powder metallurgy aluminum matrix composite brake discs in rail vehicles through strategic cooperation, so as to expand the scale of industrial production, achieve mass loading, promote the green transformation and development of rail transit industry with scientific and technological innovation, and help the country achieve the "double carbon" strategic goal.