Tensile Strengths of Silicon Carbide (SiC) Under Shock Loading

摘要

The present work was initiated to measure and compare tensile strengths (i.e., spall thresholds) of five different types/varieties of silicon carbide materials. Two of these materials were sintered, and the remaining three were hot-pressed. Three types of silicon carbides (one sintered by Sohio and. the other two hot-pressed by Cercom) were manufactured in the United States. The remaining two varieties of silicon carbides were manufactured in France. Spall strengths of these five different silicon carbide materials were measured by performing plane shock wave experiments to a maximum impact-generated stress level of 17 GPa on the light gas-gun facility at the U.S. Army Research Laboratory (ARL). The single most important result of this investigation is that spall strength of silicon carbide, irrespective of its manufacturing process, improves initially to a certain impact stress level before it begins to deteriorate under higher impact stress. The decline in the spall strength of both sintered materials and Cercom SiC-B begin at an impact stress between 3-5 GPa. SiC-N data have a very large scatter. Spall strength of the French sintered and hot-pressed material increases to an impact stress of 11.7 GPa. Its spall strength increases from 0.8 GPa at an impact stress of 1.6 GPa to 1.8 GPa at an impact stress of 11.7 GPa. In terms of spall strength, the French sintered and hot-pressed materials show the least scatter and largest increase with an increase in the impact stress. The results of the present work thus offer new challenges to modeling ceramic materials.