In the production of ceramic fiber blankets, fiber uniformity is a core indicator affecting their thermal insulation performance, tensile strength, and service life. Excessive differences in fiber diameter or uneven distribution can lead to localized imbalances in heat conduction efficiency, reducing overall insulation effectiveness. Simultaneously, uneven fiber interlacing density weakens the blanket's structural stability, increasing the risk of cracking or shedding during use. Therefore, ensuring fiber uniformity requires comprehensive control over raw material processing, fiber-forming processes, molding technology, and equipment maintenance.
The purity and chemical composition of raw materials are fundamental to fiber uniformity. High-purity raw materials reduce the introduction of impurities, avoiding fiber diameter fluctuations caused by differences in impurity melting points. For example, using synthetic powders instead of natural mineral raw materials can reduce the content of impurities such as Fe₂O₃ and Na₂O, making the melt viscosity more stable, thus forming fibers with more uniform diameters during the fiber-forming process. Furthermore, uniform mixing of raw materials ensures that all components react fully in the molten state, avoiding differences in fiber performance due to component segregation.
The fiber-forming process is a crucial step in controlling fiber uniformity. Currently, both the mainstream centrifugal spinning and blown fiber processes require high-speed rotation or high-pressure airflow to stretch the molten liquid into fibers. The spinning method optimizes fiber tensile force distribution by adjusting the spinning roller speed and fiber-forming distance. For example, in a three-roller centrifugal spinning process, the speed gradient design of rollers A, B, and C must match the molten liquid flow rate. Fluctuations in speed or excessive differences in speed between rollers can lead to uneven fiber diameter. The blown fiber process requires precise control of compressed air pressure and nozzle structure, utilizing a Laval tube to achieve supersonic airflow, causing the molten liquid to be uniformly torn into fine fibers at the moment of ejection. Insufficient airflow pressure or nozzle design defects can easily lead to fiber agglomeration or diameter differentiation.
Fiber collection and the fabrication process directly affect the uniformity of fiber distribution within the blanket. After fiber formation, the loose fibers need to be removed and uniformly settled using a fiber collector. The uniformity of negative pressure within the negative pressure chamber of the cotton collector is crucial. Uneven distribution of negative pressure under the mesh will lead to differences in fiber settling density on the conveyor belt, resulting in localized fiber accumulation or sparseness in the blanket. Furthermore, details such as the position of the blower nozzles, the adjustment of the duct annular air vent baffles, and the opening angle of the observation window at the end of the cotton collector can all dynamically optimize the uniformity of fiber distribution by fine-tuning the fiber settling path. For example, when uneven fiber distribution appears on the cross-section of the cotton collector, the fiber can be guided to settle towards the sparser area by adjusting the nozzle offset or covering part of the duct annular air vent.
Needle-punching blanket making enhances the bonding force between fibers through mechanical interlacing, while further optimizing the uniformity of fiber arrangement. Parameters such as the needle punching speed, belt speed, needle density, and needle length of the needle punching machine must be matched with the fiber diameter and blanket density. If the needle punching speed is too fast or the needle density is too high, it may damage the original fiber arrangement structure, leading to localized fiber breakage or entanglement; conversely, insufficient interlacing points cannot be formed, reducing the tensile strength of the blanket. Therefore, process parameters must be set according to fiber characteristics. For example, a lower needle punching speed and a higher needle density should be used for fine-diameter fibers to ensure sufficient fiber interlacing and minimal damage.
Equipment maintenance and process stability are the long-term foundation for ensuring fiber uniformity. Wear or aging of key components such as the spinning roller, blower nozzles, and cotton collector conveyor belt directly affect fiber forming quality. For example, slippage of the spinning roller drive belt will cause a decrease in rotation speed, resulting in insufficient fiber tensile force and a thicker diameter; partial blockage of the cotton collector conveyor belt will disrupt the uniformity of negative pressure, leading to cotton distribution deviation. Therefore, a regular inspection and maintenance system must be established to replace worn parts in a timely manner and calibrate equipment parameters to ensure stable and controllable process conditions.
Ensuring fiber uniformity in ceramic fiber blankets requires consideration of the entire process, including raw material selection, fiber formation control, cotton collection, needle punching, and equipment maintenance. By optimizing raw material purity, precisely controlling fiber forming process parameters, dynamically adjusting fiber collection paths, matching needle punching processes with fiber characteristics, and strengthening equipment stability management, the uniformity of fiber distribution can be significantly improved, thereby enhancing the thermal insulation performance and structural reliability of the ceramic fiber blanket and meeting the demand for high-efficiency energy-saving materials in high-temperature industrial fields.
