Process Breakthroughs in Gradient Porosity and High-Strength Skeleton – New Advances in Manufacturing Technology for Ceramic Fiber Filter Tubes

The manufacturing of ceramic fiber filter tubes is a systematic engineering endeavor involving fiber processing, forming control, and high-temperature sintering. The core technology lies in constructing a fiber skeleton with a gradient pore structure while ensuring sufficient mechanical strength and thermal shock resistance of the tubular body. At the initial stage, ceramic fibers of specified lengths—such as aluminum silicate fibers and mullite fibers—are mixed with organic binders, dispersants, and an appropriate amount of water to prepare a uniform slurry. Through a vacuum filtration forming process, the fibers in the slurry are directionally deposited using molds to produce tube blanks with defined wall thickness and diameter. During the forming process, by adjusting slurry concentration, filtration pressure, and mold configuration, a radial fiber packing density gradient can be achieved across the tube wall, resulting in an asymmetric structure with pore sizes gradually decreasing from the outer to the inner surface.

After demolding, the tube blanks enter the drying stage, where slow drying under constant temperature and humidity conditions is employed to eliminate internal stresses and prevent cracking. The dried blanks are then subjected to high-temperature sintering under a specific heating schedule, during which neck formation and grain-boundary fusion occur between ceramic fibers, imparting sufficient strength and rigidity to the tubes. Post-sintering treatments include end-face machining and seal assembly, yielding finished products ready for direct installation. In recent years, through optimization of fiber formulations and sintering curves, the flexural strength, thermal shock resistance, and filtration precision of the tubes have been substantially enhanced. Furthermore, the adoption of environmentally friendly water-based binders has reduced volatile organic compound emissions during the manufacturing process, making the entire production chain more green and sustainable.