Special Topic Review: Composite Materials Empowering Aerospace to New Heights - Decoding the "Made in China" Innovation of the Tiangong Space Station

In the vast expanse of the sky, 400 kilometers above the Earth, China's Tiangong Space Station orbits at a speed of 7.7 kilometers per second. This "space science ark" independently built by China is not only a milestone in the country's manned spaceflight program but also a "super testing ground" for technological innovations in composite materials. From the "heart" of the core module to the astronauts' "space wristwatches," China's composite material industry has injected powerful momentum into the aerospace sector through groundbreaking material advancements.

I. Hall Thrusters: The "Space Debut" of Ceramic Matrix Composites

As the core equipment for orbit maintenance of the Tiangong Space Station, the four LHT100 Hall thrusters installed in the Tianhe core module have achieved the first application of electric propulsion technology in a manned spacecraft. The core component, the discharge chamber, utilizes nitrogen boride ceramic matrix composites developed by the Institute of Metal Research, Chinese Academy of Sciences. This material, known as "white graphite," features a unique layered crystal structure, combining low density (2.2 g/cm³), high strength (flexural strength ≥ 150 MPa), and excellent thermal shock resistance, enabling it to withstand the high temperatures of thousands of degrees Celsius and ion sputtering produced by plasma ionization.

Unlike traditional chemical thrusters that rely on burning propellants, Hall thrusters generate ion thrust by electron beam ionization of xenon gas, offering a specific impulse 5-10 times higher. The domestic breakthrough in nitrogen boride ceramic matrix composites has not only broken the monopoly of Europe and the United States in high-end ceramic matrix composites but also saved the Tiangong Space Station approximately $200 million in annual fuel costs. During the material's research and development, the Institute of Metal Research overcame challenges such as low strength, moisture absorption, and unstable cavity discharge of nitrogen boride materials. Through optimizing the material formulation and preparation process, they successfully achieved the transition from laboratory to engineering applications.

Compared to the purely chemical propulsion system used by the International Space Station, Tiangong's electric propulsion technology represents the direction of future interstellar travel. Currently, while the X3 Hall thruster developed by the United States has a higher thrust (about 5 N), Tiangong's LHT100 model has advantages in reliability and lifespan.

II. Flexible Solar Arrays: The Energy Revolution of "Paper-Thin" Materials

The power system of the Tiangong Space Station is akin to a "space power station." Its flexible solar arrays employ multi-junction gallium arsenide solar cells, achieving a power generation efficiency of over 30% and a daily power output of nearly 1,000 kWh, equivalent to the electricity consumption of an average household for one and a half months. Remarkably, the solar array panels are only 0.7 millimeters thick yet maintain stability under extreme temperature variations from -120°C to 150°C.

The core supporting structure of the solar arrays uses silicon carbide particle-reinforced aluminum matrix composites. This material is 30% less dense than aluminum alloy while offering a 40% increase in strength, successfully addressing the lightweight and reliability challenges of the solar array deployment mechanism. The team led by Ma Zongyi from the Institute of Metal Research enhanced the billet production efficiency by over five times and increased the plate yield by 20% through powder metallurgy batch production technology and isotropic medium-thick plate plastic forming technology. Additionally, the shape memory polymer composites developed by Harbin Institute of Technology enable in-orbit controllable deployment of the solar array panels through intelligent structural design, eliminating the need for traditional electromechanical drive systems and becoming the first internationally verified flexible solar cell support technology in orbit.

The preparation of silicon carbide particle-reinforced aluminum matrix composites employs the powder metallurgy method, achieving uniform dispersion of reinforcing particles through mechanical alloying processes, with a porosity rate below 1% and mechanical properties reaching international advanced levels. Shanghai Real Industrial's patent application in 2025 further optimized the material's preparation process, making it suitable for high-end applications in aerospace, automotive, and other fields.

III. Space Watches: The "Precision Dance" of Titanium Alloy and Carbon Fiber

During the 9-hour extravehicular activity of the Shenzhou-19 astronauts, the Fiyta space watch served as a "space metronome" with its accurate timekeeping. This wristwatch features a TA15 titanium alloy case, which is only 55% the density of stainless steel yet can withstand instantaneous high temperatures of 1,000°C and deep cold shocks of -196°C. The crown and strap utilize carbon fiber composites, achieving a perfect balance between lightweight design and anti-magnetic interference through three-dimensional weaving technology.

TA15 titanium alloy is a high-aluminum equivalent near-α type titanium alloy with an aluminum equivalent of 6.58% and a molybdenum equivalent of 2.46%, offering excellent thermal stability and weldability, capable of long-term operation at 500°C. The movement gears of the Fiyta space watch employ ceramic matrix composites, maintaining a timekeeping accuracy of 0.5 seconds per day in a vacuum environment. This material technology has been extended to fields such as aviation engine blades and high-speed train brake discs.

Currently, only China's Fiyta and Switzerland's Omega can provide space watches for long-term national manned space missions. The domestic breakthrough of the Fiyta space watch not only ensures the independence of China's manned space missions but also promotes the upgrading of domestic high-end equipment manufacturing. During its research and development, the company collaborated with the Institute of Metal Research to overcome key technologies such as titanium alloy surface treatment and carbon fiber anti-magnetic interference.

IV. Industry Breakthroughs: Transitioning from "Following" to "Leading"

Data from the China Composite Materials Industry Association indicates that in 2024, China's carbon fiber production capacity exceeded 200,000 tons, with T1100-grade products achieving mass production and prepreg technical indicators reaching international advanced levels. In the construction of the Tiangong Space Station, M55J-grade carbon fiber from Zhongfu Shenying was used in the cabin structural components, while HF60-grade materials from Hengshen Co. contributed to a 15% weight reduction in large solid rocket engines.

Technological Innovation and Industrial Ecosystem

In the carbon fiber sector, Guangwei Composite Materials achieved the engineering production of T1100-grade carbon fiber through the dry-jet wet spinning process, while Zhongfu Shenying made breakthroughs in hundred-ton-level discrete and stable performance. In 3D printing technology, China took the lead in realizing continuous fiber-reinforced composite material 3D printing in space, completing printing validations of honeycomb structures and aerospace logos under microgravity conditions, laying the technological foundation for future on-orbit expansion of space stations.

Enterprise Cases and Market Expansion

Hengshen Co. developed T800-grade medium-temperature prepregs for the low-altitude economy and participated in the development of full-aircraft structures for multiple drone models. Its subsidiary in Zigong, Sichuan Province, invested 140 million yuan to build a drone support base, promoting the application of carbon fiber composites in logistics, foreign trade, and other fields. Additionally, enterprises such as Antai Composite Materials and Xinchuang Aerospace have achieved batch production of composite material components for the domestic large aircraft C919 and are involved in the development of low-altitude economy aircraft.

V. Policy Support: The "Chinese Approach" to the New Materials Industry

During the "14th Five-Year Plan" period, the state incorporated carbon-based new materials into the strategic emerging industries plan, with Shanxi and Jiangsu provinces approved to build national-level carbon-based new materials industrial bases. The Ministry of Industry and Information Technology has promoted breakthroughs in key technologies such as silicon carbide composites and ceramic matrix composites through tax incentives and special funds.

Policy Support and Local Practices

Relying on the China Electronics Technology Group (Shanxi) Silicon Carbide Materials Industrial Base, Shanxi Province is promoting the mass production of 8-inch N-type silicon carbide substrates, with an expected production value of 300,000 wafers by 2025. Jiangsu Province, through policies such as the "Nine Measures for Technological Transformation" and "Technological Transformation Special Loans," supports high-performance composite material projects, allocating 1.1 billion yuan in special debt for major projects in Fuling District in 2024.

International Cooperation and Standard Leadership

China actively participates in the formulation of international standards, promoting the internationalization of technical standards for materials such as carbon fiber and silicon carbide. Through "Belt and Road" cooperation, it exports composite material technologies to developing countries, enhancing China's voice in the global industrial chain.

VI. Future Prospects: From Near-Earth Orbit to Deep Space Exploration

With the iteration of technologies such as newton-level Hall thrusters and space 3D printing, composite materials will continue to empower strategic fields such as deep space exploration and space-air shuttle missions. For example, graphene aviation batteries offer over 50% higher energy density, potentially providing efficient energy for lunar bases; metamaterial technologies may enable stealth and efficient communication for spacecraft.

Technology Roadmap and Challenges

In the short term, China will focus on enhancing the lightweight, high-temperature resistance, and radiation resistance of composite materials. The medium- to long-term goal is to achieve intelligent and self-healing functions in materials. However, major challenges remain, including cost control of high-end materials, large-scale industrialization, and international technological blockades.

Industrial Collaboration and Talent Cultivation

The development of composite materials requires collaboration across the entire industrial chain of "materials-design-manufacturing." Universities and enterprises should strengthen industry-university-research cooperation to cultivate interdisciplinary talents. Meanwhile, the government should further optimize the policy environment and guide social capital investment in basic research and pilot-scale conversion.

From the "space heart" of nitrogen boride ceramic matrix composites to the "intelligent wings" of shape memory polymers, China's composite material industry is writing a new chapter of "material power" with the Tiangong Space Station as its stage. In the future, with continued technological breakthroughs, composite materials will provide lighter, stronger, and smarter "Chinese solutions" for humanity's exploration of the universe.

References: China Manned Space Engineering Office, China Composite Materials Industry Association, Institute of Metal Research, Chinese Academy of Sciences, etc.