Cyclic fatigue life characteristics of ceramic balls under variable thermal shock loadings

Abstract

Ceramic balls made of silicon nitride (Si3N4) exhibited excellent mechanical properties are used in high-end components operating at ultra-high speeds, and high and low temperatures. Previously, studies have involved the cyclic mechanical and thermal fatigue tests of ceramic balls under a constant temperature. However, the thermal fatigue characteristics of brittle materials have not been theoretically or experimentally investigated under variable thermal shock loadings to date. Herein, cyclic thermal shock fatigue (CTSF) life characteristics of Si3N4 ceramic balls subjected to single- and two-stage cyclic thermal shock loadings were theoretically and experimentally investigated using a probabilistic model based on slow crack growth concept in conjunction with Weibull distribution. Consequently, the fracture criterion derived from the probabilistic model was related to the linear cumulative damage law (Miner’s rule). Thereafter, the predicted CTSF life of the ceramic balls was compared with the experimental results to validate the proposed probabilistic model. Therefore, the proposed model accurately reproduced the experimental results to a certain extent.