Effect of the reduction treatment on the basalt continuous fiber crystallization properties

Basalt continuous fibers were treated in H-2/Ar atmosphere at 650 degrees C and 700 degrees C. The Fe-57 Mossbauer spectroscopy indicated that after the treatment at 650 degrees C all ferric cations reduced to ferrous. Reduction at higher temperature leads to metallic iron formation. DSC and XRD data indicated that crystallization process in reduced basalt fibers carried slower. Glass transition temperature decreases after the reduction due to the increase of amount of ferrous cations, that act as modifiers. Due to Fe2+/Fe3+ ratio changing spinel-like phase crystallization ability decreases. Crystallization in reduced basalt fibers starts at lower temperature. The tensile strength of reduced fibers is higher than the tensile strength of basalt continuous fibers that were annealed at the same condition in air. (C) 2013 Elsevier B.V. All rights reserved.