| abstract |
To provide a heater tube for immersing a molten metal made of a silicon nitride sintered body having a higher thermal conductivity and density and a better heat transfer rate than those of conventional ones. A molten metal immersion heater tube (1) has a cylindrical heater accommodating portion (4) having a closed end (2) and an open end (3), and the heater accommodating portion (4) includes silicon nitride and a compound containing yttrium. And a compound containing magnesium, and the surface roughness Ra of the outer peripheral surface of the heater housing 4 is 0.5 μm or more and 10 μm or less. [Selection] Figure 2 |