| 摘要 |
PROBLEM TO BE SOLVED: To provide a ceramic roll where the specks are inhibited from transferring to the surface of a rolled metal foil, and a manufacturing method thereof.SOLUTION: A long ceramic roll 1 formed of sintered silicon nitride has an average pore area ratio of 0.2% or less in the usable region from the initial diameter to the disposal diameter, with the average pore area ratio on the central axis side from the disposal diameter being higher than the average pore area ratio in the usable region, having congested pores with an equivalent circle diameter of 0.3 to 10 μm and substantially no congested area of pores with a diameter of 80 μm or more at least in the usable region. The sintered silicon nitride includes Mg and at least one rare earth element in a total amount of 3 to 20 mass% in terms of oxides, with a mass ratio between Mg and the rare earth element in terms of oxides (MgO/oxide of the rare earth element) of 0.2 to 5. |
