Plate impact response of ceramics and glasses

Abstract

Soft-recovery plate impact experiments have been conducted to study the evolution of damage in polycrystalline Al2O3 samples. Examination of the recovered samples by means of scanning electron microscopy and transmission electron microscopy has revealed that microcracking occurs along grain boundaries; the cracks appear to emanate from grain-boundary triple points. Velocity-time profiles measured at the rear surface of the momentum trap indicate that the compressive pulse is not fully elastic even when the maximum amplitude of the pulse is significantly less than the Hugoniot elastic limit. Attempts to explain this seemingly anomalous behavior are summarized. Primary attention is given to the role of the intergranular glassy phase which arises from sintering aids and which is ultimately forced into the interfaces and voids between the ceramic grains. Experiments are reported on the effects of grain size and glass content on the resistance of the sample to damage during the initial compressive pulse. To further understand the role of the glass, plate impact experiments were conducted on glass with chemical composition comparable to that which is present in the ceramic. These experiments were designed to gain further insight into the possibility of ‘‘failure waves’’ in glasses under compressive loading.

A review of the processing, composition, and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

“…Sintered or hot pressed alumina is commercially available in a wide range of purities, with strength increasing with increasing purity. Some very high flexural, tensile and compressive strength values have been reported in the literature for carefully prepared aluminas, produced from high-purity powders, with low porosity, small grain size, and lacking the glassy grain boundary phases typically present in commercially supplied alumina [135,[151][152][153]. These materials are not representative of commercially available alumina, and so are not included here.…”

Origin of compression-induced failure in brittle solids under shock loading

“…The preexisting defects simply reduce the threshold impact velocity, facilitate damage dynamics and increase failure wave velocity. The seemingly conflicting phenomena observed in previous experiments, including incubation time 17 , failure wave velocity variations 18,46 , and surface roughness effects 7,12 , can all be explained consistently with nucleation and growth of microdamage, and the effects of loading strength and preexisitng defects.…”

Computer Aided Multi-scale Design of SiC-Si3N4 Nanoceramic Composites for High-Temperature Structural Applications

“…To reduce computational time, results from Case C at iteration 7 are used as the starting design in this case, just before mean values of the deformation energy are used to construct the RSA. The table shows that the robust optimum microstructure is given by the design x * = [40,24,36,21,9,8,8]. Again, we notice how the robust optimum design is very similar to the conventional design (Case C), where variations in the objective function are not considered.…”

“…(20) 1 ( Table 9 shows the results of the sequential approximate optimization under uncertainty algorithm. It details the current design (x n ) and candidate design (x n *) per iteration, showing that the optimum microstructure is given by the design x * = [10,19,9,7,3,8,8]. This design results in a more intermediate microstructure, compared to the results from cases A-D where designs did not show compromised microstructures.…”

“…The fracture resistance of single phase and multiphase polycrystalline materials has been analyzed in past using analytical, computational, and experimental approaches, [8], [9], [10], [11], [12], and [13]. However, leaving aside some recent promising approaches (such as [14]) analyses have not considered explicit combined role of GBs and second phase particles in the microstructure dependent fracture of these nanocomposites.…”