In cryogenic applications such as cryogenic storage tanks and aerospace refrigeration equipment, the performance stability of ceramic fiber boards directly determines the reliability of thermal insulation systems. To investigate the effects of cryogenic environments on ceramic fiber boards, this experiment selected two types of ceramic fiber boards—1260 standard grade and 1400 high-purity grade—as samples. Three typical cryogenic temperature gradients (-80°C, -120°C, and -196°C, liquid nitrogen temperature) were simulated. Multidimensional testing analyzed the patterns of performance changes.
Prior to testing, both ceramic fiber board samples underwent pretreatment: they were cut to standard dimensions of 300mm × 300mm × 50mm, dried at 105°C for 4 hours to remove moisture, and their initial thermal conductivity, compressive strength, and bulk density were precisely measured. Testing was conducted using a cryogenic constant-temperature chamber. Samples were placed in different temperature environments and maintained at constant temperatures for 24 hours. Three parallel samples were set for each temperature gradient to ensure data reproducibility.
Thermal conductivity test results indicate that cryogenic environments significantly optimize the thermal insulation performance of ceramic fiber boards. The thermal conductivity of the 1260 standard ceramic fiber board was 0.042 W/(m·K) at room temperature, decreasing to 0.038 W/(m·K) at -80°C, further decreasing to 0.035 W/(m·K) at -120°C, and stabilizing at 0.032 W/(m·K) at -196°C. The thermal conductivity of 1400 high-purity ceramic fiber boards is 0.038 W/(m·K) at room temperature, dropping to 0.029 W/(m·K) in deep-cold environments at -196°C. This occurs because air molecule movement within the ceramic fiber board slows in deep-cold environments, weakening convective heat transfer and further reducing overall thermal conductivity. The high-purity type ceramic fiber board exhibits more pronounced thermal insulation optimization due to its higher fiber purity.
Mechanical property tests reveal that low temperatures cause a slight increase in brittleness of ceramic fiber boards while maintaining stable strength. The compressive strength of 1260 standard-grade ceramic fiber boards is 0.8 MPa at room temperature and 0.78 MPa at -196°C, representing a decrease of only 2.5%. The 1400 high-purity ceramic fiber board exhibits a compressive strength of 1.1 MPa at room temperature and 1.07 MPa at -196°C, representing a decrease of less than 3%. Scanning electron microscopy (SEM) observation revealed no fiber fractures or structural delamination in either ceramic fiber board under cryogenic conditions. Only a slight reduction in inter-fiber bonding strength was observed locally, with complete recovery of properties upon return to room temperature and no irreversible damage.
Structural integrity was validated through freeze-thaw cycles: the ceramic fiber boards underwent 20 alternating cycles between -196°C and ambient temperature, with a 2-hour interval between each cycle. After completion, the 1260 standard-grade ceramic fiber board exhibited a volume shrinkage rate of 0.3%, while the 1400 high-purity grade showed 0.2% shrinkage—both well below the 1% industry safety threshold. No surface cracks or flaking occurred. This demonstrates the boards’ sustained structural stability during alternating deep-cold and ambient temperature cycles, making them suitable for deep-cold equipment requiring frequent start-stop operations.
This experiment confirms that ceramic fiber boards not only exhibit enhanced thermal insulation performance in cryogenic conditions but also meet stringent requirements for mechanical strength and structural integrity. Among them, the 1400 high-purity ceramic fiber board, with its superior properties, is more suitable for ultra-cryogenic scenarios below -120°C, providing scientific basis for selecting insulation materials for cryogenic equipment.
