Scaling laws of structure and fragmentation parameters of ZrO2 ceramics.

Abstract

The effects of loading intensity and material structure on statistical regularities of fragmentation were studied. The material under investigation is zirconia-based ceramics. The samples with different pore structure (10%, 20%, 30%, 45%, 60% - the porosity of the powder used for ceramic sample sintering) were tested. The experimental data on dynamical fragmentation of ZrO2 ceramics allowed us to construct the fragment size distribution (spatial scaling) and the distribution of time interval between fractoluminiscense pulses (time scaling). The power law exponent of spatial scaling depends on ceramics porosity and intensity of loading, which has a considerable influence on the power law exponent for samples with highest porosity (60%). Two types of the distribution function for time interval were observed. For ceramics of low porosity (less than 60%) the distribution is fitted by two power laws with different exponents, and the distribution of time intervals for ceramics of highest porosity (60%) obeys one power law. An increase in porosity leads to the growth of the number of single fracture events (the number of middle and short intervals), as a consequence of missing the second power law exponent. Statistics of pore systems in two samples with 20% and 60% porosity was studied using X-ray Computed Tomography (CT). Analyzing more than a thousand of cross section images for every sample, we get a cumulative pore area distribution, and a relationship between area and perimeter. The best fitting for pore area distribution are: 1) two power laws for sample with highest porosity (60%); 2) double exponential law for low porosity (20%). The area – perimeter relation satisfies a power law.