Effect of Lubricant on the Surface Structure of Aluminosilicate Fibers

Commercial aluminosilicate fibers of the nominal composition 45 wt% Al₂O₃, 54 wt% SiO₂ have similar bulk properties but different surface chemistries, depending on whether they were formed with (WL) or without (NL) the aid of a mineral-oil lubricant. Both fiber samples are X-ray amorphous as formed; they have similar crystallization temperatures and have activation energies for crystallization of 751 and 854 kJ/mol for samples NL and WL, respectively. Fiber surface properties differ markedly, as indicated by diffuse reflectance infrared transmission spectroscopy and X-ray photoelectron spectroscopy. These techniques show that carbon from the lubricant degradation and/or combustion is incorporated into the melt, whereupon it reacts with nonbonding oxygens in the Al-O network to form network carbonates.