1993 Volume 57 Issue 7 Pages 756-760
The relationship between the effect of crystallization by anorthite and mechanical properties was investigated by the 4-points bending test and fracture toughness testing (SEPB) in alumina particulate glass composite. PbO-borosilicate glass and CaO-borosilicate glass composite were prepared and crystallized in the interface between glass and alumina or particulate by anorthite and alumina. As crystallized, the bending strength decreased in vacuum because of the initial defects, and increased in air and water because of a decrease of the stress corrosion. On the other hand, the bending strength decreased in all environment where the glass is particulate by anorthite and alumina. By using the AE method, in the noncrystallized specimens, even particulate by anorthite, it was found that the microcrack extended rapidly because of stress corrosion if one microcrack processed. However, if the crystallization occur in the interface between glass and alumina, the crack extension stopped, leading to an increase of the bending strength. Because fracture toughness increased in all environment by the crystallization treatment, it was demonstrated to control the microfracture by crystallization and hence develop the method to obtain the material having the higher reliability in both air and water.
