2001 年 8 巻 294 号 p. 333-338
Fracture toughness of fine ceramics depends on notch root radius, crack length and grain size. The effects of notch root radius on fracture toughness were investigated using gypsum and polymer gypsum composite. The notch root radius were varied in size ranging from 0.1 mm to 1.0 mm. Experiments were conducted at room temperature. The results were discussed based on the process zone size fracture criterion. The relationship between notch root radius and fracture toughness was in good agreement with the theoretical one deduced from the criterion. Polymer gypsum composite was confirmed to be excellent materials showing high fracture toughness and bending strength in compared with gypsum.