Silicon carbide, with single‐edge precracked beam (SEPB) toughness greater than 7 MPa·m1/2, was made by hot‐pressing using Al–B–C (ABC) or Al–Y2O3 (YAG) as additives. The hardness of SiC processed with a liquid phase was always less than SiC densified without a liquid phase despite having a similar or finer grain size. With increasing Al content, the ABC system changed from trans‐ to intergranular fracture with a drop in hardness and a two‐ to threefold increase in SEPB toughness. Strength and Weibull modulus for materials processed with a liquid phase were higher than those of solid‐state densified SiC. Ballistic testing, however, did not show any improvement over SiC densified with B and C additives. Depth of penetration was controlled by hardness of the SiC‐based materials, while V50 values for 14.5 mm WC–Co cored projectiles were in the range of 720–750 m/s for all materials tested.
Processing additives and conditions allow a wide variation in microstructures and mechanical properties for Sic-based ceramics prepared by hot pressing. Five experimental materials with a wide variety of microstructures and mechanical properties were fabricated and compared with SIC-N, a commercially available material. Quasi-static fracture modes varied from predominantly transgranular to primarily intergranular, leading to a twofold increase in the single-edged precracked beam (SEPB) fracture toughness. Hardness varied due to an order of magnitude change in grain size, while porosity varied by less than one percent. Ballistic v 5 0 performance was measured using 14.5 mm projectiles shot at ceramic/composite targets. The relative ranking of ballistic performance is discussed in terms of microstructure and mechanical properties.The data indicate that a wide variety of Sic-based materials can give good ballistic results, contradicting some of the theories about what is important to improve ceramics for armor. Several materials were as good or better than Sic-N in these tests. The relative ballistic ranking was not predictable based solely on hardness, toughness, strength, grain size, elastic modulus, or fracture mode. Although Weibull modulus correlated with ballistic performance, this is likely coincidental since strength values extrapolated to a low failure probability based on the respective Weibull distributions could not rank the ballistic results.
INTRODUCTIONSic is the ceramic armor of choice for moderate to heavy threats due to the likely amorphitization of BhC at high pressures. The key to making improved armor is to understand what controls the ballistic performance of the armor system. This paper focuses only on the ceramic portion of the ballistic package realizing that the performance is tied to the system. In previous work' using 7.62 mm diameter by 51 mm long WC-Co cored ammunition, it was
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.