On the critical thickness of ceramic to shatter WC-Co bullet cores

In this paper, the 7.62 mm x 51 mm FFV round consisting of a tungsten carbide core (1550 HV) and copper gilding jacket was fired at silicon nitride, titanium diboride, tungsten carbide and silicon carbide ceramics. Of particular interest is the thickness of the ceramic required to change the penetration mechanism from that of an intact body to broken body, and finally, to becoming completely fragmented during penetration. There appears to be a correlation between the acoustic impedance of the ceramic and the thickness required to shatter the core. The effect of ceramic hardness is less-marked. The existence of a critical thickness to shatter the core suggests that it is not only the magnitude of the shock-stress imparted to the core but the duration of the shock-stress that is important in causing shattering of these relatively brittle cores.