Papers by Author: Young Moo Kim

Abstract: An infiltration technique using W-Cu composite powder has been developed to enhance microstructural uniformity of W-Cu pseudo-alloy. W-Cu composite powder, manufactured by reduction from WO3 and CuO powder mixtures, were blended with W powder and then cold isostatically pressed into a cylindrical bar under 150 MPa. The pressed samples were pre-sintered at 1300 oC for 1 hour under hydrogen to make a skeleton structure. This skeleton structure was more homogeneous than that formed by using W and Cu powder mixtures. The skeleton structures were infiltrated with Cu under hydrogen atmosphere. The infiltrated W-Cu pseudo-alloy showed homogeneous microstructure without Cu rich region.

Abstract: A new tungsten heavy alloy with hybrid structure was manufactured for the kinetic energy penetrator. The tungsten heavy alloy is composed of two parts: core region is molybdenum added heavy alloy to promote the self-sharpening; outer part encompassing the core is conventional heavy alloy to sustain severe load in a muzzle during firing. The fracture surfaces of the specimen is observed after ballistic tests. The core region revealed brittle behavior with W/W inter-granular fracture which activates self-sharpening. On the other hand, outer part exhibited conventional ductile fracture mode. From ballistic test, it was found that the penetration performance of the hybrid structure tungsten heavy alloy is higher than that of conventional heavy alloy. This heavy alloy is thought to be very useful for the penetrator in the near future.