Effects of synthesis parameters on the microstructure and phase structure of porous 316L stainless steel supported TiO2 membranes

Porous stainless steel (PSS) supported TiO₂ membrane was synthesized from colloidal TiO₂ sol by the sol–gel technique. Morphology and phase structure of the obtained membranes were regulated through optimizing the synthesis parameters including organic binders, aging periods of the parent sol and concentrations of the casting solutions as well as the sintering temperatures. Polyvinyl alcohol (PVA) 1750 was found to be feasible to fabricate TiO₂ membrane with relatively flat surface and homogeneous morphology without crack. The aging period of the parent sol, which was revealed to be very important to the morphology of the particles deposited in the membranes on PSS, was decided to be 24 h. The concentration, under which the membranes could avoid macro-pores and have a uniform thickness of approximately 8 μm, was regulated to 0.0036 mol/l. Besides, a homogeneous microstructure with grain sizes of 0.08–0.2 μm was obtained in the membrane with a pure rutile phase when sintered at 850 °C. The obtained PSS supported TiO₂ membrane with homogeneous microstructure and rutile phase may be very promising for practical applications.