| Popis: |
The objective of this study was to investigate the stress and strain levels present in quartz and alumina-bearing porcelains, and correlate these values to mechanical strength. Data indicated that residual strain increased as filler particle size increased, but only to a critical value, after which strain decreased, indicating a relaxation caused by spontaneous microcracking of quartz grains. The maximum strain was observed for samples containing 87 pm quartz grains. Analysis of stresses and strains generated between quartz grains and the surrounding glass phase demonstrate that cracking must first occur in the weaker filler grains, not the glass phase, as is commonly reported. Mechanical strength was maximum in samples containing 26 μm quartz grains, decreasing rapidly upon increase of quartz size. Acoustic emission was used to attribute this trend to the generation of microcracks upon induced loading. |
