| 摘要 |
PURPOSE:To obtain alpha-alumina filament having high tensile strength, high elasticity and high alumina content, by using alumina powder and a basic aluminum salt as main raw materials and carrying out preparation of spinning stock solution spinning, calcinating and heating under specific conditions. CONSTITUTION:In process for preparing a spinning stock solution, an aqueous solution of a basic aluminum salt is blended with 10-40wt% corresponding amount based on total oxide amount in fiber of alumina powder having <=0.1mum average-particle diameter, 4-10wt% corresponding amount of a spinning auxiliary and, if necessary, <=3wt% corresponding amount sintering auxiliary, adjusted to water content in such a way that the viscosity at 25 deg.C becomes 1,000-10,000 poises to form slurry. In a spinning process, the slurry is subjected to dry spinning at 5-50m/min spinning velocity and the spun filament is heated to <=150 deg.C at <=1,500 deg.C/min rate of heating to give filament. In a calcining process, the filament is passed through a heating zone of two stages at 250-500 deg.C and 700-900 deg.C in a ratio of retention time of the first and the second zones of 2-4:1. The calcination is carried out under heating at 1,400-1,600 deg.C. |
