Wei Bingbo, academician of the Chinese Academy of Sciences
After 38 years of hard work, especially in the 32 years since the implementation of the manned space project, under the specific guidance of Academician Gu Yidong, the chief expert in space science of China's manned space project, and through two generations of struggle, we have achieved scientific and technological achievements of international attention within the scope of a number of research objectives we have selected
Our team is building, developing, and researching, from drawing design to parts installation, and experimental equipment debugging, and the experimental equipment developed has completely independent intellectual property rights
It is necessary to find out the superiority of doing scientific research in the space environment and use it to guide the improvement of the scientific research environment on the ground, which is an aspect that is more likely to produce new quality productive forces
"Lookout" Newsweek reporter Hu Yongshun
If you want to make the flight performance of the fighter better, on the one hand, it is to reduce the weight of the aircraft, and on the other hand, to improve the performance of the engine, niobium alloy can make the engine withstand higher temperatures, thereby improving the performance of the fighter. However, niobium is a refractory metal, with a melting point as high as 2468 °C, and it is difficult to find a suitable container in smelting.
Space has a special microgravity environment, and if the floating niobium alloy can be studied by laser heating, melting, cooling, supercooling and solidification in the space station, the container problem can be well solved.
This vision is becoming a reality. The space materials science and technology research team led by Academician Wei Bingbo of Northwestern Polytechnical University has successfully obtained the key thermophysical properties of refractory alloy melt by using the containerless material experiment cabinet of China's space station, and has made a number of new scientific discoveries in space solidification preparation, which has effectively promoted the expansion of refractory alloys from ground research to outer space research.
Wei Bingbo, academician of the Chinese Academy of Sciences and chief scientist of space materials science of China's manned space project, told the reporter of "Lookout" Newsweek, "Compared with European and American space powers, the gap between our space materials science is that the research coverage is not as good as theirs, but we have an independent space station, and we have come to the forefront of the world's space materials science in the 15 to 20 material systems selected by the mainland." It will take 10~15 years for our research to lead the world, which is exactly the goal to be achieved in the 10~15 years of our space station operation. ”
The continental space station has achieved important results in the research of refractory alloys
Lookout: What is the significance of studying space materials science? How did continental space materials science develop?
Wei Bingbo: Space materials science is an interdisciplinary field formed by the integration of materials science and space technology, and its main research content is to explore the physical and chemical properties, phase transformation process laws, synthesis and processing principles of various materials, and their final service performance in the supernormal environment characterized by microgravity, containerless, high vacuum and strong radiation in outer space. The development direction is firstly to use the special environmental conditions of outer space to conduct materials science research, and secondly, to lay a solid scientific foundation for the space application of various materials.
The vigorous development of manned spaceflight in the past 50 years has promoted the emergence and rise of space materials science. Throughout the research process of countries around the world, this branch of materials science originated from sporadic space carrying experiments in the 60s of the 20th century, experienced the irrational stage of trying to establish space material processing plants in the 70s and 80s, and entered a rational and stable research period in the 90s. Through the Space Shuttle, the United States conducted a large number of space material science experiments in the eighties and nineties. Since the beginning of the 21 st century, the United States, Russia, Europe, and Japan have jointly established the "International Space Station," which has become the largest space science research platform in orbit after the Soviet Union's "Mir" space station.
Since the launch of the 863 program in 1986, the mainland has officially deployed space materials scientific research. At that time, Mr. Chen Xichen of the Institute of Physics of the Chinese Academy of Sciences was the responsible expert of the expert group of the 863 Program, responsible for the organization of space materials scientific research, and the research team included the Institute of Physics, the Institute of Metals, the Institute of Ceramics, the Institute of Semiconductors, the Institute of Thermophysics, the Institute of Mechanics, the Lanzhou Institute of Chemistry and other units of the Chinese Academy of Sciences, as well as Northwestern Polytechnical University, where I was studying for a doctorate, as well as Harbin Institute of Technology, Beijing University of Aeronautics and Astronautics and other institutions. At the same time, the National Natural Science Foundation of China has also deployed related projects in space materials science.
In 1992, the mainland launched a manned space program, which strongly promoted the research of space materials science. Space materials science research has gradually developed with the "three-step" strategy of China's manned spaceflight.
Generally speaking, after 38 years of hard work, especially in the 32 years since the implementation of the manned space project, under the specific guidance of Academician Gu Yidong, chief expert in space science of China's manned space project, and through two generations of hard work, we have achieved scientific and technological achievements that have attracted international attention within the scope of a number of research objectives we have selected. For example, a variety of functional crystal materials made by the team of researcher Liu Xuechao of the Institute of Ceramics of the Chinese Academy of Sciences, friction lubrication materials made by the team of academician Liu Weimin of the Lanzhou Institute of Chemical Physics, phase separation materials made by the team of researcher Zhao Jiuzhou of the Institute of Metals, and the spatial rapid solidification of multiple alloys made by the team of Northwestern Polytechnical University. We have been at the forefront of these studies, and some of them have taken the lead. However, Europe and the United States and other aerospace powers started early and covered a wide range of research, in contrast, our space materials scientific research still needs to strive to become stronger and bigger.
Lookout: This year, you led your team to publish a series of scientific research papers on space materials conducted on China's space station.
Wei Bingbo: Compared with the solid phase, the liquid phase and gas are more sensitive to the space environmental conditions, so the liquid structure and properties of various materials, the movement law of the liquid phase and the gas phase, the dynamics of the liquid-solid and gas-solid phase transition, and the regulation mechanism of the material forming process have always been the main tasks of space materials scientific research. With the joint support of the Space Application Project of the China Manned Space Project and the Basic Science Center of the National Natural Science Foundation of China, our space materials science and technology research team has successfully completed important experiments such as the determination of liquid properties and rapid solidification of refractory alloys under microgravity conditions with the help of the Chinese space station, and has achieved five results:
First, the accurate determination of the liquid properties of refractory alloys. In microgravity, the melt of the suspended alloy is perfectly spherical. On this basis, we accurately determined the key physical properties that are essential for the preparation of materials such as the density and heat-to-spoke ratio of liquid niobium alloys and zirconium alloys in the temperature range from ultra-high temperature to extremely deep subcooling.
Second, the nucleation control of the alloy surface. Under the condition of small supercooling, the surface of the liquid alloy has multi-point nucleation and solidification is spherical. However, under heavy supercooling, the single-point nucleation of the surface causes the solidification to deviate from the spherical shape. By adjusting the number and position of nucleation points, a new idea is provided for the morphological control of alloy materials.
Thirdly, the surface structure of the alloy is controlled in the microgravity environment. Under the condition of microgravity, the electrostatic field is used to form a periodic corrugated structure and a special vortex structure on the surface by excitation of the alloy melt, which provides a new method for regulating the surface microstructure.
Fourth, the surface of the droplet solidifies and shrinks. We found that the craters after microgravity solidification have a specific pattern. By adjusting the solidification shrinkage kinetics, different porosity distribution patterns can be obtained, so as to reduce the influence of porosity on the microstructure properties of the alloy.
Fifth, the "decoupling" growth of eutectic alloys. Eutectic alloys are characterized by coupled growth, however, in the solidification experiment of refractory niobium alloys carried out on the Chinese space station, we were surprised to find that the two phases of niobium and niobium-silicon compounds, which were originally eutectic, can be "decoupled" to grow. This discovery reveals a new path of material manipulation, which indicates that higher performance alloys can be prepared in the space environment.
"Drawing the dragon on the ground, finishing the eye on space" develops space material science
Lookout: How did you lead the team to conduct scientific research on space materials after returning from studying abroad?
Wei Bingbo: There are two technical routes for space materials science research: one is to use space stations, space shuttles, spacecraft and other space vehicles to conduct real space science experiments; The second is to carry out ground simulation experiments by means of free fall, suspension technology and high-strength physics. The main contradiction restricting the development of this discipline is that materials science is an experimental science closely integrated with engineering technology, and a large number of systematic space science experiments must be carried out. But space experiments are not only constrained by high costs, but also have limited opportunities to fly on board. Therefore, ground simulation and space experiments may be the optimal way for the development of space materials science.
After I returned to China in 1992, it took me 30 years to develop five sets of experimental equipment, which we can basically systematically use on the ground in five ways: electromagnetic levitation, pneumatic levitation, electrostatic levitation, ultrasonic levitation, and metal melt free fall, to create some space simulation conditions. Our team is building, developing, and researching, from drawing design to parts installation, and experimental equipment debugging, and the experimental equipment developed has completely independent intellectual property rights.
Lookout: What is the working principle of the electrostatic levitation experimental system currently being carried out in space?
Wei Bingbo: In the ground laboratory, electrostatic levitation is the use of the electric field provided by the electrostatic site to overcome gravity, so as to achieve a container-free state. It can be used in a wide range of materials, as long as the sample generates a sufficient amount of charge, it can be suspended, and the material can remain in a stable suspension state in a vacuum environment, avoiding the influence of media. Compared with electromagnetic levitation, ultrasonic levitation and pneumatic levitation, electrostatic levitation does not have electromagnetic stirring, ultrasonic cavitation and air flow disturbance, and the external field has little influence on the sample. Therefore, the material can be melted and solidified without containers in an almost completely static environment, so that the melt of the material is easy to obtain deep subcooling, which is convenient for real-time in-situ determination of the physical and chemical properties of the supercooled state and the solidification process.
Compared with ground electrostatic levitation, the electrostatic suspension of the space station does not need to overcome gravity, and only needs to control the position of the sample, and its principle is to adjust the magnitude and direction of the coulomb force of the sample according to the change of the sample position, so that it is dynamically "positioned" in the set position. Compared with the ground experiment, the required voltage is smaller, and the interference to the sample is much less than that of the ground experiment, which in turn provides more ideal scientific experimental conditions, such as the liquid sample is more round and the sample oscillation is more ideal under microgravity conditions.
Get out of your own space materials science path
Lookout: What is the future development direction of materials science in mainland China?
Wei Bingbo: The mainland has become a big country in materials science and materials industry. With the scientific exploration of deep space, deep sea and deep earth, the application space scope of materials and the environmental boundaries of synthesis preparation and forming processing have been greatly expanded.
First, in deep space, through manned spaceflight, we have formed a matrix in the low-earth orbit of outer space, and if we keep going down the line of space, we will go from the space station to deep space exploration, the moon and even further. Deep space is faced with extreme environments such as high radiation, which brings new problems to the development of space materials science. In the 10~15 years of operation of the continental space station, we will make more impactful and truly original achievements in materials science and engineering.
Second, in the deep-sea, with the advancement of deep-sea exploration technology, we are able to conduct scientific research and resource development in a high-pressure and highly corrosive environment in the deep sea. This requires materials that must not only withstand extremely high water pressures, but also have excellent corrosion resistance. The mainland's research in the field of deep-sea materials will further promote the development of marine engineering and marine resources, and provide safer and more reliable material support.
Third, in the deep ground, scientific exploration and resource extraction allow us to penetrate deep into the Earth's interior, which requires materials to work stably for long periods of time in high-temperature, high-pressure, and highly corrosive environments. The development of materials suitable for deep extreme environments is not only of great significance for geology and mineral resource exploitation, but also provides material guarantee for the development of new energy sources such as nuclear energy and geothermal energy.
Lookout: How to give full play to the role of China's space station and promote the world's leading material science research in mainland China?
Wei Bingbo: After years of hard work, the mainland has ushered in its own space station era, which has opened up broader prospects for the development of space materials science. To give full play to the maximum role of China's space station, it is necessary to walk on two legs, and two kinds of scientific research must be done on the space station.
The first type of scientific research is the space science problem that cannot be simulated on the ground and needs to be studied in the space station. For example, Marangoni convection, hydrostatic pressure disappearance, etc., these phenomena exhibit completely different properties under microgravity conditions than those of ground experiments. These studies help us understand and control fluid behavior, crystal growth processes, and develop new materials and processes that are not possible on the ground. Through experiments on the space station, we can obtain accurate data that cannot be achieved on the ground, providing a valuable theoretical basis for the development of new materials. However, it is very difficult to achieve a major breakthrough in space science research, because there is no no such thing as a scientific research no-man's land, and what we are doing is more to expand on the discoveries of our predecessors.
The second type of scientific research is scientific research that can be done in the sky and on the ground, but it is necessary to find out the superiority of doing scientific research in the space environment and use it to guide the improvement of the scientific research environment on the ground. For example, in the extremely special space environment, we find and solve the core problems of material synthesis, fluid mechanics, and life science technology, which in turn guide ground scientific research, which is more likely to generate new quality productivity. In the next 10~15 years of operation of the space station, I hope for this scientific research model. ■
![Hey, hello everyone! Mr. 🐏 Yang will share with you an engineering and chemical SCI journal today! THE FOLLOWING IS THE JOURNAL INFORMATION: JOURNAL NAME: 📚 DRYINGTECHNOLOG[fig]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)