The traction transmission system is an important component of high-speed railways and is crucial for the conversion of mechanical and electrical energy. The traction motor that maintains high-speed operation of high-speed rail can be called the "heart" of high-speed rail. The key to manufacturing it is aramid paper, an insulating material with high electrical strength, high temperature resistance, and fire resistance.

What does a piece of paper have to do with high-speed rail?

Isn't paper a flammable material?

Aramid paper,

It's not just ordinary paper,

The reason why it is so "tough" is that its main raw material is aramid fiber

——Under the premise of equal quality,

The strength of aramid fiber is about 5 times that of steel.

Image source of aramid insulation paper: Zhuzhou Times New Materials Technology Co., Ltd. official website

01

What is aramid fiber that claims to be capable of building rockets?

The full name of aramid fiber is "aromatic polyamide fiber". In the 1960s, aramid fiber was first developed by DuPont in the United States and successfully industrialized.

The series of "papers" developed from aramid fibers can be used to prepare honeycomb sandwich composite materials, which have the characteristics of light weight, high specific strength and stiffness, impact resistance, excellent sound insulation, heat insulation and flame retardant properties, good high-temperature stability and electromagnetic wave transmission performance. They are strategic materials urgently needed for major national projects.

For a long time, high-end aramid materials have been monopolized by foreign companies, and China has long been subject to others, paying huge "expenses" every year for this. In order to truly grasp the initiative of competition and development, China began research on aramid paper at the end of the 20th century and the beginning of the 21st century.

Image source of aramid honeycomb paper: Zhuzhou Times New Materials Technology Co., Ltd. official website

02

Intangible cultural heritage techniques imprint the label of "Made in China" on high-tech materials

Intangible cultural heritage, why is it related to cutting-edge technology again? Little did they know that the transformation from aramid fiber to aramid paper was achieved using the wet papermaking technique of the Cai Lungu method.

In 105 AD, Cai Lun of the Eastern Han Dynasty improved the papermaking process and produced high-quality and inexpensive paper. Since then, human civilization has taken a big step forward, and papermaking has become one of China's the Four Great Inventions.

On the road of research and production of domestically produced aramid materials, researchers have innovated and developed traditional techniques such as "pounding" and "copying", and carried out a series of work from single material development, insulation system design to prototype production verification. Ultimately, the independent aramid paper achieved comprehensive application performance at the same technical level as imported materials.

In 2019, the first batch of aramid paper developed and manufactured by Zhuzhou Times Huaxian Material Technology Co., Ltd. was officially put into production, breaking through the hydraulic headbox forming technology and high-temperature rolling technology, realizing the engineering application and domestic substitution of independent aramid paper in major fields such as high-speed rail and aerospace, and promoting innovation and breakthroughs in China's bottleneck field of new materials. At present, CRRC aramid paper has been widely used in high-speed trains, locomotives, and subway traction motors.

High speed railway traction motor. Image source: Central Video

Not long ago, relevant researchers also introduced the application of self-developed aramid paper in traction power equipment for rail transit in the CCTV program "China in Intangible Cultural Heritage".

On site experiments have shown that honeycomb made of aramid paper can not only withstand high temperatures of 500 ℃, but also, due to its strong morphology, can even withstand the test of heavy trucks rolling over it! The 20 ton truck was rolled without any damage.

The host lit both regular paper and aramid paper at the same time, and found that the aramid paper extinguished as soon as it left the fire. Source of animation: Central Video

Nowadays, with the efforts of researchers, the localization and independent development of high-performance aramid insulation paper and aramid honeycomb paper have been achieved, making this thin "paper" widely used in high-precision fields such as rail transit, aerospace, and new energy. The integration of intangible cultural heritage tradition and modernity has also given us pride and confidence from ancient wisdom.

Salute to the amazing Chinese researchers!

Source | Translated from "Science Popularization China", welcome to download "Science Popularization China" and become a proud "Science Popularization Information Officer"

Original title: "Unexpectedly, the paper that cannot be burned by an open flame at 500 ℃ is actually the insulation material in the 'heart' of high-speed rail