Author | Reporter Deng Yajing Correspondent Liu Shiliang Liu Xuan
Source | State-owned Xiaoxiang media
Rail transit is a business card of Hunan, what is the next trend?
Lighter, more energy efficient, more low carbon.
Hunan's construction of a world-class industrial cluster for rail transit is bound to cultivate and drive a number of new stars in the industrial supply chain enterprises.
On December 14, it was learned from Hunan Xiangtou Group that its holding subsidiary Jintian Aluminum High-tech Co., Ltd. (hereinafter referred to as "Jintian Aluminum") "120km/h rail transit vehicle powder metallurgy aluminum matrix composite brake disc" project passed the evaluation of scientific and technological achievements.
Academician Huang Boyun of the Chinese Academy of Engineering, Professor Xiao Jiayu of the National University of Defense Technology and other 7 experts unanimously assessed that the project in the industry for the first time using powder metallurgy technology to prepare 120km/h rail transit vehicle aluminum matrix composite brake discs, in the aluminum matrix composite material composition design, forming technology and industrial continuous production and other aspects of the formation of a complete set of powder metallurgy aluminum matrix composite brake disc production technology, the overall technology of the project ranks at the international advanced level, some of the technology reached the international leading level.
This means that Hunan is the next city in the rail transit industry chain to achieve import substitution, and has made a key breakthrough in achieving weight reduction, energy conservation and emission reduction for rail vehicles such as subways.
△The scene of the judging meeting.
A new trend in rail vehicles: lightweighting
Brake discs are the key components under the spring of rail transit vehicles. At present, the brake disc products used in domestic rail transit are still dominated by cast iron brake discs of traditional materials, and with the development trend of vehicle lightweighting and the impact of energy-saving and emission-reduction policies, they are being replaced by revolutionary new material products aluminum matrix composite brake discs.
Compared with traditional brake discs, aluminum matrix composite brake discs have the advantages of light weight, good heat transfer and friction performance. According to CRRC's relevant data, the use of aluminum matrix composite brake discs instead of traditional cast iron brake discs can reduce weight by about 60%, which can not only reduce the under-spring weight of vehicles, meet the requirements of axle load limit, but also significantly reduce the energy consumption of subway operation. Relevant calculations show that a 6-group subway train with aluminum matrix composite brake discs can achieve weight reduction of about 2.4 tons, save about 50,000 kWh of electricity per year, and reduce carbon dioxide emissions by about 50 tons.
△Review experts learn more about powder metallurgy aluminum matrix composite brake discs.
"At this stage, China's aluminum matrix composite brake discs are mainly imported from developed countries such as Germany. It is expected that during the '14th Five-Year Plan' period, aluminum matrix composite brake discs will occupy the mainstream of the market, we are expected to replace foreign imported products, and have obtained bulk orders from customers. The relevant person in charge of Jintian Aluminum Company told the state-owned Xiaoxiang Rong Media reporter.
Five years of scientific research achievements: substitution of imports
As the first enterprise in China to industrialize nitrogen atomization technology to produce fine spherical aluminum powder, Jintian Aluminum is located in Luxi County, Xiangxi Prefecture, and has exclusively drafted and formulated the industry standard of "Nitrogen Atomized Aluminum Powder" and led the drafting of the national standard of "Nitrogen Atomized Aluminum Powder". During the "13th Five-Year Plan" period, the company laid out to the downstream of the industrial chain, carried out the research and development of powder metallurgy aluminum matrix composites and related products, and after nearly five years of scientific research, built the first large-size powder metallurgy aluminum matrix composite lightweight brake disc production line in China, with an annual production capacity of about 12,000 pieces.
Talking about the research process, the relevant person in charge of Jintian Aluminum Company frankly said that the project team invested nearly five years to break through the common technical problems of metallurgical combination in the process of aluminum powder oxide film affecting powder metallurgy, established a multi-series database of high-performance aluminum matrix composite materials, and the volume fraction of silicon carbide can reach up to 70%; developed the key process technology of large size, complex structure, and integrated powder metallurgy near net forming to achieve stable, efficient and continuous production of aluminum matrix composite brake discs.
"Jintian Aluminum innovatively used powder metallurgy technology to prepare aluminum matrix composite discs for 120km/h rail transit vehicles for the first time in the industry, which solved the technical bottlenecks such as the easy aggregation of existing aluminum matrix composite brake disc reinforcement phases, the limited content of reinforced phase additions and the difficulty of avoiding metallurgical defects in the preparation process, greatly improved the mechanical, wear-resistant, temperature-resistant and other properties of aluminum matrix composite brake discs, and successfully realized the preparation technology innovation and performance upgrade." The company's aforementioned person in charge told state-owned Xiaoxiang Rong Media that at present, it has been applied to the Shenzhen urban rail comprehensive detection vehicle, which is in good condition and can fully realize the substitution of imported products.
△ Huang Boyun, academician of the Chinese Academy of Engineering (third from the left), and other experts conducted on-site inspections.
As a major rail transit country, as of the first half of 2021, a total of 8448.67 kilometers of urban rail transit lines have been put into operation in 49 cities in mainland China. According to CRRC's 2020 annual report, the sales volume of urban rail vehicles exceeded 9,000, and it is expected that during the "14th Five-Year Plan" period, the annual number of new urban rail vehicles in China will be stable at about 10,000.
"The results of the previous research and development have laid a solid foundation for the development of aluminum matrix composite brake discs for rail transit vehicles with higher speed grades such as 160km/h, and will effectively expand the product market space." It is estimated that by 2025, the annual demand for aluminum matrix composite brake discs for rail transit vehicles in China will exceed 45,000 pieces. The person in charge of the Jintian Aluminum project said that focusing on the strategic needs of national high-end transportation equipment lightweight, the company will continue to increase investment in research and development, comprehensively carry out technical research on high-performance powder metallurgy aluminum matrix composite brake discs, form a unique competitiveness in the core braking components of rail transit vehicles, and help Hunan build a world-class industrial cluster of rail transit.
Editor-in-chief | Xie Gongmei
Executive Editor 丨Huang Shangrun
Proofreading | Small billion
Responsible Editor | Excellent