アルミナ繊維の溶融アルミニウム合金への濡れ性

抄録

Wettability of alumina fibres containing 15%SiO₂ to liquid aluminum alloys were measured using a dip coverage method, dipping a bundle of fibres into liquid metal. The wetting process could be analyzed by the same model applied in the previous work. Although the value of overall reaction rate constant k₀ for fibre dipped into pure aluminum at 1273K slightly decreased, the incubation time increased considerably comparing with that for block. On the other hand, the value of k₀ for fibre to Al-Ca system alloy at 1273K increased higher than that of block. These experimental results were explained based on the Wenzel's rule describing the effect of the roughness of solid/melt interface on the wettability. Calcium and magnesium additions improved the wettability at 1023K by forming their oxides or silicide at or near the interface. On the other hand, silicon showed an inferior effect on the wettability. The dependence of the wettability of fibre to a Al-3%Ca alloy on temperature gave the activation energy of 335kJ/mol, which was almost the same as the single binding energy of Si-O of 370kJ/mol. Therefore, the wetting process of alumina fibre containig 15% SiO₂ is possibly controlled by the rate of dissociation of SiO₂.