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

• Influence of sintering atmospheres on SS hollow fibers were investigated.
• Metal oxidation was found for SS hollow fibers sintered in air and CO2.
• Inert atmospheres of N2 and He caused carbon remaining in SS hollow fibers.
• H2 atmosphere was effective for obtaining high-performance SS hollow fibers.

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 1 h, the as-sintered SS hollow fiber showed high bending strength of >200 MPa and nitrogen permeance up to 9.5×10−5 mol s−1 m−2 Pa−1.

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