Characterization of thermal-shock cracks in ceramic bars

Abstract

Experimental analysis of the cracking in the ceramics subsequent to water quenching have been conducted to clarify the uncertainties of cracking in the ceramics when subjected to thermal shock. The results here indicate that at the critical point of quench temperature, the crack density and the depth reached the minimum and the maximum limits, respectively. On increase of the quench temperature, the crack density increased rapidly before reaching its saturation point, while the crack depth initially decreased rapidly and then increased gradually before reaching its saturation point.

Fractal characterization of ceramic crack patterns after thermal shocks

“…Since ceramics are brittle materials, this crack can be speculated as the principal factor that reduces the strength of the ceramic. This phenomenon is the same with the results of Bahr and Xu, they indicated that the cracks on the surface (No. 3 and No.…”

“…The stress is largest on the surface and decays with depth, while the fractal dimension is sensitive to this fine distinction. Previous research has found that, when quenching temperature T just passed critical temperature T c , the crack depth and the crack density have an opposite tendency . That means, although the density of cracks increases at 300°C, the crack depth decreases to a certain extent.…”

“…Inspired by Bahr's research works, in the last decade, many researchers studied crack patterns after thermal shocks, in order to reveal mechanisms between residual strength and crack characteristics . For thin ceramic specimens, Shao conducted thermal shock testing in the temperature range higher than the critical thermal shock temperature difference (Δ T c ) and showed that the depth of long crack was gradually increased in regime III, which supported the standpoint of Davidge and Bahr, although Hasselman had opposite results.…”

“…Shao considered the influence of long crack depth and density on residual strength offset each other to some extent, which was also revealed from the results of the finite element method. From the experimental aspect, Xu suggested that at the critical point of quench temperature, the crack density and the depth of ceramic bars reached the minimum and the maximum limits, respectively, which provided a quantified relationship between crack density and depth.…”

Strange matter and strange stars in a thermodynamically self-consistent perturbation model with running coupling and running strange quark mass

“…This way of extending the applicable range of the perburbative calculation was shown to be reasonable for the one-flavor case [54]. It has also been shown, for the massless two-flavor case, that the renormalization subtraction point should be taken as a function of the summation of the biquadratic chemical potentials while the additional term not only keeps the thermodynamics self-consistent, but also produces reasonable results [59]. In the present paper, we extend this thermodynamically enhanced perturbative QCD (EPQ) model to the actual SQM with massless up (u) and down (d) quarks plus massive strange (s) quarks.…”