| 摘要 |
PROBLEM TO BE SOLVED: To provide a furnace core tube which controls heat stress, and the reaction with strong alkali components generated from the material to be heat-treated in the furnace core tube, has an extended service life, and is of a high industrial use, and a furnace core tube composite member using the same.SOLUTION: The furnace core tube includes mainly alumina and magnesia or either of alumina or magnesia, and any one of the oxide materials among composite materials containing not less than one kind selected from among SiO, ZrO, MgO, and AlOand different form the main components described above, has a fine particle-distributed layer 20, not less than 80 vol.% of which is made up of fine particles having a particle size of 0.1-1 μm in the region at least 30 μm deep from the surface to the depth direction, and a coarse particle-distributed layer 21, not less than 60 vol.% of which is made up of fine particles having a particle size of not less than 0.5-2 μm on the outer circumferential side deeper than the fine particle-distributed layer. |
