HEATER TUBE MADE OF CERAMICS

摘要

PURPOSE:To enhance toughness of the heater tube by utilizing slurry having specified viscosity and manufacturing the heater tube so that an SiC whisker is orientated and dispersed in an Si3N4 matrix nearly parallel to the wall face of the heater tube two-dimensionally at random. CONSTITUTION:Slurry having <=3.0 poise viscosity is obtained by mixing about 75wt.% (hereinafter %) Si3N4 powder having about 1mum particle diameter, 5-30% SiC whisker having about 0.1-1mum diameter and about 5-100mum length and about 15% cordierite-based sintering adjuvant with water. This slurry is introduced into a gypsum mold and a green molded body having >=60% density is obtained. This molded body is roasted at 1700 deg.C for 3 hours in the N2 atmosphere. A tough heater tube is obtained wherein the SiC whisker 1 is orientated and dispersed in an Si3N4 matrix 3 nearly parallel to both the outer surface 2 of the heater tube and the wall face of the inner surface 2' two-dimensionally at random. Furthermore tension stress imparted on the outer surface is reduced and progress of the generated fine cracks 4, 4' is stopped.