| 摘要 |
PROBLEM TO BE SOLVED: To prolong the life of a doctor blade by forming the edge part of a doctor blade of a zirconia ceramic containing a specific component. SOLUTION: The edge part 3a of a doctor blade 1 is formed of a zirconia ceramic based on ZrO2 as a main component with the content of 8-15mol% of MgO and at least 10mol% of a monoclinic crystal structure. That is, a distortion or a microcrack is generated around the monoclinic crystal by causing the generation of the monoclinic crystal structure to such a high molar percentage of at least 10mol%. Consequently, an external stress is absorbed by the microcrack and also the crack, if generated, is dispersed by the microcrack. Thus the high tenacity of the edge part 3a is obtained. In addition, the outstanding resistance against a thermal shock is obtained because the microcrack moderates a rapid expansion caused by the thermal shock. If the monoclinic crystal structure exceeds 50mol%, the transverse breaking strength is deteriorated. On the other hand, if the MgO content is not more than 80mol%, the monoclinic crystal is increased beyond the limits of necessity. If the MgO content is equivalent to 15mol% or more, the strength of the edge part is lowered. |
