Abstract: A composition of a ceramic shell mold, a method of using the ceramic shell mold in investment casting of a structural part, and a structural part formed therefrom is provided. The ceramic shell mold has one or more investment layers formed from slurries and interlayer barriers formed over the investment layers. The interlayer barriers include a self-lubricating soluble solution and grit having a predetermined grit size that is a function of the feature spacing within the structural part. The grit size of each sequential interlayer barrier is at least as large as the grit size of each preceding sequential interlayer barrier.

Abstract: An improved barrel for use in a weapon includes a housing which is cast as one piece of a directionally solidified superalloy which is free of generally spherical, randomly oriented crystals. The housing has first properties in a direction extending parallel to its central axis and properties which are different than the first properties in a direction transverse to the central axis of the housing. The superalloy forming the housing may be directionally solidified with a columnar grain crystallographic structure. Alternatively, the superalloy of the housing may be directionally solidified with a plurality of single crystal sections, one or more of which extend between opposite end portions of the housing. As another alternative, the superalloy may be directionally solidified as a single crystal which extends between opposite end portions of the housing.