| 摘要 |
The present invention is intended to drastically improve a precision polishing characteristic of a cordierite-based sintered body which has low thermal expansibility, high dimensional long-term stability and high rigidity (high elastic modulus). The cordierite-based sintered body comprises cordierite as primary components, and one or more selected from the group consisting of La, Ce, Sm, Gd, Dy, Er, Yb and Y in an oxide-equivalent amount of 1 to 8 mass%, without any crystal phase other than a cordierite crystal phase. A mass ratio of primary components of the cordierite satisfies the following relations: 3.85 ‰¤ SiO 2 / MgO ‰¤ 4.60, and 2.50 ‰¤ Al 2 O 3 / MgO ‰¤ 2.70, and the cordierite-based sintered body after being subjected to precision polishing has a precisely polished surface with an average surface roughness (Ra) of 1 nm or less. |
