Inviscid melt spinning: As-spun crystalline alumina fibers

Inviscid melt spinning yielded the first crystalline alumina fibers directly from the melts. In this experimental process, a liquid jet having a melt viscosity of <10¹ poise (vs>10⁴ for fiberglass) is extruded into propane and is thus chemically stabilized (vs rapidly quenched) before it forms Rayleigh waves and breaks up into droplets. This letter describes a 65.5% alumina-zirconia fiber, an 81.5% and a 90.6% alumina-calcia fiber, a 98.6% alumina-magnesia fiber, and a 100% alumina fiber. The δ-allomorph was identified as the crystalline phase of the melt spun 100% alumina fibers, compared to the α-allomorph reported for FIBER FP, a slurry spun and sintered 100% alumina fiber.