Effects of sintering atmospheres on properties of stainless steel porous hollow fiber membranes

Stainless steel (SS) is one of excellent materials for fabrication of hollow fiber membranes because of its good mechanical property. Phase inversion technique is a promising method for preparation of SS hollow fibers. The sintering step is critical for controlling the quality of SS hollow fibers by removal of organic additives and activation of particle binding. In this work, we prepared SS porous hollow fiber membranes by combined dry-wet spinning and sintering technique. The influence of sintering atmosphere (air, CO₂, N₂, He and H₂) on microstructure and properties of SS hollow fibers were investigated extensively. It was found that air and CO₂ could lead to metal oxidation while inert atmospheres (He and N₂) caused carbon remaining in SS hollow fibers. By contrast, H₂ atmosphere was effective in removing organic additives without metal oxidation. High mechanical strength could be achieved for the hollow fiber membranes sintered in H₂ atmosphere. At 1100°C for 1h, the as-sintered SS hollow fiber showed high bending strength of >200MPa and nitrogen permeance up to 9.5×10^-5mols^-1m^-2Pa^-1.