At the moment of being unsealed, [video] went straight to the scene: materials for traveling back to Earth to the Chinese space station | scientific experiments | space station

Will there be any changes in the materials for traveling to the Chinese space station and returning to Earth? On June 21, the reporter of Jiefang Daily Shangguan directly attacked the moment when it was opened at the Shanghai Institute of Silicate, Chinese Academy of Sciences.

Five ceramic tubes, approximately 30 centimeters long, are arranged in a row on the desktop. They have been in the high-temperature material experimental cabinet of the Chinese space station for over 200 days and returned to the ground on June 4th with the Shenzhou-15 manned spacecraft.

The staff dismantled the "07" tube, which is an experimental sample from the Shanghai Institute of Ceramics. Eight white ceramic gaskets were taken out. In order to protect the experimental samples from fragmentation, their function is equivalent to the "foam cushion" in the express delivery. Amidst everyone's breathless anticipation, a quartz transparent glass tube about 10 centimeters long was taken out.

Liu Xuechao is holding a glass tube. Photo by Huang Haihua

"It looks very good with obvious holes," said Liu Xuechao, chief designer of the high-temperature materials science experimental system and researcher at the Shanghai Institute of Ceramics, picking up a glass tube and carefully examining it. Only a portion of silver indium selenium semiconductor materials can be seen growing tightly against the glass tube wall, and their "pores" can be clearly seen from the outside.

It is hard to imagine that this material grew at a speed of 1 millimeter per hour in microgravity space and lasted for more than 80 hours. "This is our first time verifying this material in space," said Liu Xuechao.

Why let materials travel in space? Follow the Liberation Daily News reporter to unlock new knowledge together.

[It's like having a good 'medicine guide']

"After all, I have been 'sharpening a sword' for 8 years, and I am still very excited. Some team members thought of receiving experimental samples today, and last night they were so excited that they lost sleep," said Liu Xuechao.

There are currently 14 scientific experimental cabinets on the Chinese space station, including two material science experimental devices, namely the "high-temperature material experimental cabinet" and the "containerless experimental cabinet". The scientific experimental systems are led by the Shanghai Institute of Ceramics.

High temperature material cabinet for space station. Respondents provide pictures

The space station has no container material cabinet. Respondents provide pictures

Why let materials travel in space? Liu Xuechao gave an example: Monocrystalline silicon has always been difficult to break through the bottleneck of "large-size". It was through space experiments that foreign scientists made an important discovery, and the key is to precisely control its "growth" interface. Nowadays, monocrystalline silicon can grow to over one meter on the ground. "In microgravity space, it is more convenient to measure various parameters of materials. By studying their spatial mechanisms, it can in turn guide research on the ground, which is of great significance for China to break through the key scientific and technological issues of 'bottleneck'."

Crystal growth requires good crystal seeds, but it is often difficult to prepare on the ground. Scientists have found that crystals grown in space have a defect density two orders of magnitude lower than those grown on the ground. "If a good 'embryo' is first cultivated in space and then taken to the ground for 'growth', it is like having a good 'medicinal primer', and the subsequent 'growth' trend will be better," said Liu Xuechao.

The high-temperature material experimental cabinet can support high-temperature heating, directional solidification, rapid cooling, real-time measurement and other functions of materials under microgravity, and is one of the latest generation of space material experimental devices in China. The maximum heating temperatures of the two high-temperature furnaces are 1200 ℃ and 1600 ℃, respectively. The number of samples heated in a single batch reaches 16, both of which are at the international leading level; X-ray transmission imaging is the first internationally conducted manned space station, which can observe the heating and solidification process of samples in real time.

What exactly is "containerless"

The fourth batch of samples from the "containerless experimental cabinet" also returned to the ground together from the space station. What exactly is "containerless"?

Materials are usually packed in a container, but the container often brings pollution, and the pressure generated by the container wall on the material can also lead to uneven stress during the preparation process. If there is no reaction with the container, higher purity and more uniform materials can be obtained. Can we use other external forces to make it float in space without a container?

This may sound a bit fanciful, but it eventually came true. As the first and second in orbit "containerless" experimental facility in China and internationally, the "containerless experimental cabinet" was launched into space from the core module of the space station on April 29, 2021. It has been operating steadily for more than 700 days, with a maximum heating temperature of 3000 ℃, reaching the international leading level.

How to implement "containerless"? "It's like launching a shell, first loading it into a magazine, then releasing it in space, allowing it to float in the air, and then recycling it back into the magazine after the experiment is over," Yu Jianding, chief designer of the containerless material science experimental system and researcher at the Shanghai Institute of Ceramics, told Liberation Daily Shangguan News.

Yu Jianding is holding a container free material sample box. Photo by Huang Haihua

It is reported that the "containerless experimental cabinet" has obtained a large amount of key scientific data that is difficult to obtain on the ground. On the one hand, it can provide guidance for exploring new metal materials with application prospects, such as aircraft engine blades; On the other hand, it also helps to explore the laws of planetary evolution and the origins of Earth's environmental changes.