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Herein, the breakdown mechanism of alumina‐based ceramics (Al2O3–ZrO2) is studied. The specimens are characterized for their density, phase structure, micromorphology, breakdown process, and breakdown channel by micro computed tomography, high‐speed cameras, etc. The study reveals that the dielectric breakdown stability of the samples shows a decreasing trend and the dielectric loss shows an upward trend with the increase of ZrO2 content. The tetragonal phase zirconia is beneficial to enhance the dielectric breakdown strength of the sample, which is related to the martensitic transformation to prevent crack propagation. Before the ceramic breakdown, the insulating oil first breaks down, causing electric sparks. Once the ceramic breakdown occurs, the charges are rearranged, and a large amount of heat energy is generated instantly to melt the substance around the breakdown channel and erupt to the surface to form pits under the action of high internal stress. [ABSTRACT FROM AUTHOR]

There is growing awareness of the need to protect system circuit from the abnormal impact loading environment. Impact mechanical sensor can immediately hold back system circuit in the extreme environment. Especially, mechanical response component of it must possess the characteristics of high fracture strength and high Weibull modulus simultaneously. Engineered stress profiles glass (ESP glass) is the best choice for achieving these two performances in all kinds of material. In many cases, it is desirable that once the impact mechanical sensor has served its function that ESP glass then fractures into very small fragments. ESP glass with controlled static fracture properties so far has been carried out theoretically and experimentally, whereas impact properties of it are rarely performed. In order to understand mechanical properties of ESP glass under impact loading environment, the mechanical behavior of the simply supported beam including ESP glass is investigated by theoretical formulae and finite element method (FEM) simulation in this paper. The theoretical computational results of the dynamic flexural strength of ESP glass are consistent with the simulation results of it. Results gained show that the relation between static mechanical properties and dynamic mechanical properties of ESP glass can be established by dynamic coefficient.

Irradiation-induced UV–VIS absorptance spectra and electron paramagnetic resonance X-band spectra of some cerium (Ce)-doped borosilicate glasses and alumino-borosilicate glasses were studied, and it was found that the addition of calcium oxide could reduce irradiation resistance of Ce-doped (alumino-)borosilicate glass. As a result, the concentration of calcium oxide in the Ce-doped irradiation-resistant (alumino-)borosilicate glass should be reduced. [ABSTRACT FROM PUBLISHER]

Abstract: Optical absorption spectra, electron paramagnetic resonance (EPR) spectra, Raman spectra of a borosilicate glass after irradiation by 10MeV proton, 1.85MeV electron and 60Co-γ ray were studied. The process of irradiation inducing color centers in the glass was discussed. The band gap of the glass before and after 60Co-γ ray irradiation was studied using Mott and Davis''s theory, and it was found that calculated change of the band gap introduced a paradox, because Mott and Davis''s theory on the band gap cannot be adopted in the study on the irradiated glass. [Copyright &y& Elsevier]

Before and after 11 kGy 60Co-γ irradiation as well as after 150°C bleaching, reflectivity and absorption coefficient of a borosilicate glass were calculated from the intensity of transmitted light and the intensity of reflected light measured using an integrating sphere. The irradiation induced absorption in the studied wavelength range, while it only made the reflectivity change obviously in the range 4.5–5.6 eV (275–221 nm). The absorption coefficient spectrum and the reflectivity spectrum of the irradiated glass both recovered to a degree after 150°C bleaching. The relative error of irradiation-induced absorption coefficient calculated neglecting reflectivity change was studied, and the relative errors in the studied wavelength range theoretically increase when the thickness of glass sheet decreases, so if irradiation-induced absorption coefficients are studied using a thin glass sheet, reflectivity changes should be considered. The band gap of the glass was studied using Mott and Davis's theory, and it was found to reduce after irradiation, then after 150°C bleaching, it increased but still smaller than the one before irradiation. [ABSTRACT FROM PUBLISHER]