Use of Edge-on Impact Tests with Synchrotron-Based MHz Radioscopy to Investigate the Multiple Fragmentation Process in SiC Ceramics

Abstract

Ceramic materials are widely used all around the world in protective solutions as front plate of bilayered configurations, a metallic or composite material being used as backing to absorb the kinetic energy of fragments. However, during the impact, an intense fragmentation process composed of numerous oriented cracks develops in the ceramic plate due to high-loading rates tensile stresses. The edge-on impact (EOI) configurations constitute one of the best testing techniques to analysis the dynamic fragmentation process in brittle materials. A metallic cylindrical projectile hits the edge of a prismatic target of thickness smaller than the projectile diameter with an impact velocity ranging from 100 to 300 m/s. The damage process is usually observed on the lateral surface with a digital ultra-high speed camera (“open configuration”). However, the fragmentation cannot be observed in the bulk of the target except if a post-mortem analysis is conducted (“sarcophagus configuration”). In the present work, in addition to this classical testing methods, EOI experiments have been conducted in the European Synchrotron Radiation Facility (beamline ID19) with X-ray radioscopy technique using the 16-bunch operation mode. Targets, 60 × 30 × 6 mm³, made of silicon carbide were placed in an intense X-ray beam (mean photon energy about 30 keV) providing an observation field of 12.8 mm in width and 8 mm in height, and impacted with projectile velocities ranging from 150 to 200 m/s. A Shimadzu HPV-X2 camera lens-coupled to a fast scintillator (LYSO:Ce) was used to visualize the fragmentation process through the thickness with an interframe time set to 1065 ns. The fragmentation pattern was compared to data obtained in classical “open configuration” with surface visualization and to post-mortem analysis obtained in “sarcophagus configuration”.