| 摘要 |
PROBLEM TO BE SOLVED: To obtain a ceramic roll having appropriate quality corresponding to actual stress condition and excellent reliability by producing a ceramic roll from the ceramic material essentially consisting of the materials satisfying a specific formula. SOLUTION: A ceramic roll is made of a ceramic material essentially consisting of silicon nitride or sialon having a parameter η of <=1.3 in a general formula for mixed mode fracture of opening mode and in-plane shear mode, that is, (K1 /K10 )+η(K2 /K10 )=1 (whereas K1 , K2 is an opening mode and stress magnification coefficient respectively, K10 is critical a stress magnification coefficient). Further, the ceramic material contains Mg component of 0.5-3wt.% in term of MgO, one or more components of Yb, Er of 3-10wt.% in term of Yb2 O3 or Er2 O3 and an acicular particle of silicon nitride or sialon, which has a minor diameter of 0.01-0.3μm as crystal phase and an aspect ratio of >=15, of 20-50wt.% in term of the total. |
