Unveiling the Lubricant Used by the Yutu Lunar Exploration Device
author: Leila
2024-08-05
In the early morning of December 2, 2013, the Chang'e-3 lunar exploration satellite was launched from the Xichang Satellite Launch Center on the Long March-3 carrier rocket. Chang'e held Yutu and flew to the moon. Yutu will then conduct a three-month lunar patrol.
All moving parts on Earth cannot do without lubrication, and so do space equipment. Space probes are the first to explore space. When conditions are ripe in the future, humans may migrate to other planets. So, what kind of lubricant can meet the requirements of space probes?
The environment on Mars and the Moon is worse than on Earth, with high vacuum, large temperature difference, strong radiation and corrosive environment, and dust storms. In these cases, liquid lubricants will evaporate quickly, and only solid lubricants can be selected.
Commonly used solid lubricants include: layered solid materials (such as graphite, molybdenum disulfide, boron nitride, etc.), other inorganic compounds (such as lithium fluoride, calcium fluoride, lead oxide, lead sulfide, etc.), soft metals (such as lead, indium, tin, gold, silver, cadmium, etc.), polymers (such as nylon, polytetrafluoroethylene, polyimide, etc.) and composite materials.
Like the selection of liquid lubricants and greases, the selection of solid lubricants is also based on various conditions such as working conditions and environment to select the type of solid lubricants that can meet the requirements. The research and development of aerospace lubricants is also based on the environment and working conditions of lubricant use, and the best lubricating materials and lubricating solutions are selected based on tribology.
On Mars and the Moon, solid lubricants are chosen because:
1. The vacuum and weightless environment of space make any liquid lubricant used on Earth vaporize in an instant and cause pollution to equipment (such as optical equipment or electronic equipment).
2. At extremely high temperatures, liquid lubricants quickly decompose and oxidize.
3. At extremely low temperatures, liquid lubricants solidify or become extremely viscous, losing their liquid lubrication function. Some solid lubricating materials have lubrication capabilities even at -273 degrees Celsius.
4. Strong radiation environments can cause liquid lubricants to decompose and fail.
5. Liquid lubricants will adhere to impurities in an environment with a lot of dust and impurities, while solid lubricants such as graphite and boron nitride can adapt to such environments.
6. On space probes, liquid lubricants add a heavier burden to the equipment, while solid lubricants are relatively light and easy to carry.
7. In the case of large changes in equipment load, working conditions, and environment, the lubrication ability of solid lubricants is more stable.
Compared with liquid lubricants, the main disadvantages of solid lubricants are:
1. The friction coefficient of solid lubrication is greater than that of fluid lubrication.
2. Some solid lubricants have poor heat dissipation, such as polymer-based lubricants.
3. The self-repairing ability of solid lubricants is not as good as that of fluid lubrication, so damage to the lubricating layer will affect the overall lubrication performance and service life. However, there are related technologies for repair, such as the use of carbon nanotube materials.
Lubricants are a key link in supporting the operation of machinery and equipment. They contain rich "health" information about the machine and can reflect the operating status of the machine and equipment. Therefore, it is very important to sample and analyze the lubricants. In 2008, the Shenzhou VII manned spacecraft was successfully launched, and the work project for the first spacewalk of Chinese astronauts was determined to be the retrieval of the solid lubricating material test device.
Industrial lubricant product classification and functions
Selection principles of industrial lubricants
