October 13,2026
Ultra-low-temperature bearings generally refer to operating conditions below -60°C, and even as low as -253°C. Core applications are concentrated in scenarios requiring the pumping or handling of liquefied gases.
Liquefied Natural Gas (LNG) and Liquefied Petroleum Gas (LPG) Pumps
LNG is stored and transported at temperatures of approximately -160°C or lower, while LPG operates below -47°C. Cryogenic submerged pumps are the core equipment of LNG receiving terminals and fueling stations, with bearings operating fully immersed in cryogenic liquids.
Aerospace and Rocket Cryogenic Propulsion Systems
This is the most demanding scenario. Liquid hydrogen (LH₂) reaches temperatures as low as -253°C, and liquid oxygen (LOX) and liquid nitrogen (LN₂) are similarly in deep cryogenic states. Turbopump bearings must operate at extremely high speeds (DN values up to 4 million) without conventional lubrication, and liquid hydrogen itself can only provide extremely limited cooling and boundary lubrication effects.
Superconducting Equipment and Cryogenic Motors
Superconducting magnetic levitation cryogenic submerged pumps utilize the cooling environment provided by superconducting materials at low temperatures to achieve non-contact bearing support, fundamentally solving the cryogenic lubrication challenge.
Other Deep Cryogenic Industrial Processes
These include liquid nitrogen pumps, liquefied gas pumps, and certain material handling equipment that must operate in extremely cold regions (such as below -50°C).
Hybrid Ceramic Bearings (Most Widely Used Solution)
These use 9Cr18 or G95Cr18 stainless steel rings combined with silicon nitride (Si₃N₄) ceramic balls. Ceramic balls offer high hardness and low density, making them less prone to adhesion with steel rings in liquid nitrogen, with stable friction coefficients. PTFE (polytetrafluoroethylene)-based cages transfer to the raceways during operation to form a solid lubricating film, compensating for the inability to use grease. Nikkiso's hybrid ceramic bearing products can operate safely within the range of -253°C to 350°C. Liquid nitrogen bench tests (-196°C, 40,600 rpm, 90 minutes) have verified their reliability.
Full Ceramic Bearings (Preferred for Extreme Conditions)
Inner and outer rings and rolling elements are all Si₃N₄ ceramic materials. During low-temperature operation, a self-lubricating film can form on the ceramic contact surfaces, requiring no external lubrication. Experiments with 6206 Si₃N₄ full ceramic bearings under continuous temperature cycling from 93K (-180°C) to 293K, as well as heavy loads and oil-free lubrication conditions, have demonstrated good cryogenic adaptability. The disadvantages are high requirements for cage materials (need for wear resistance and low expansion) and relatively high brittleness, requiring caution under impact loads.
Special Stainless Steel Bearings (Dedicated for Cryogenic Applications)
Patented technology uses ultra-tough martensitic high-nitrogen stainless steel (nitrogen content 0.1–0.4 wt%) for rings. After cryogenic treatment (-65°C to -198°C), the retained austenite content is reduced to below 7 vol%, with hardness reaching HRC 58–61, while avoiding volume changes and microcracks caused by austenite-to-martensite transformation at low temperatures. AISI 440C is a classic material for stainless steel bearings, but its toughness and corrosion resistance are limited below -160°C, and it is gradually being replaced by high-nitrogen steels and hybrid ceramic solutions.
Superconducting Magnetic Levitation Bearings (Ultimate Non-Contact Solution)
These utilize the magnetic levitation force between high-temperature superconductors and permanent magnets to achieve completely non-contact support. Since the working medium (such as liquid nitrogen) can directly provide the cooling environment for the superconductor, no additional cooling system is required. This is a solution that fundamentally addresses the cryogenic lubrication problem, but it is still in the research and early application stage, suitable for special scenarios such as cryogenic submerged pumps.
Key Selection Considerations
The fundamental contradiction in ultra-low-temperature bearing design is that conventional lubricants (greases) completely fail at deep cryogenic temperatures, and reliance must be placed on solid transfer lubrication (provided by cage materials) or self-lubrication (ceramic materials). When selecting, key attention must be paid to: cage materials (PTFE-based composites such as Salox M and Rulon A are proven reliable choices), thermal expansion matching between rings and balls (the combination of ceramic balls and steel rings maintains stable clearance at low temperatures), and the toughness of materials at low temperatures (to avoid brittle fracture).
If your equipment requires specially customized bearings for ultra low temperature environment but standard bearings cannot meet the requirements, please feel free to contact us. We can provide customized solutions tailored to your specific needs.
