PREPARATION OF POROUS MATERIALS BY BACTERIALLY ENHANCED CORROSION OF FE IN IRON-TITANIUM HOT-PRESSED PLATES

Sintered iron-titanium plates, presenting several titanium-rich and ir on-rich phases, were submitted to bacterial corrosion in acidic media containing dissolved oxygen in order to produce a porous material to b e infiltrated by lithium and used as an anode for thermal batteries. T he iron-rich phases were selectively attacked, and the presence of Thi obacillus ferroxidans bacteria in the electrolyte accelerated the corr osion. The postulated mechanism involved an anodic reaction of Fe, yie lding Fe2+ ions, which underwent rapid bacterial oxidation to Fe3+ in the electrolyte. Reduction of these Fe3+ ions to Fe2+ ions constituted the cathodic reaction. The corrosion reaction rate was limited by fer ric hydroxide precipitation. The largest pore volume obtained was 3.1 x 10(-4) m(3) kg(-1).