Consolidating cubic boron nitride (cBN) typically requires either a matrix of metal bearing materials that are undesirable for certain applications, or very high pressures within the cBN phase stability field that are prohibitive to manufacturing size and cost. We present new methodology for consolidating high stiffness cBN composites within a hexagonal boron nitride (hBN) matrix (15-25 vol%) with the aid of a binder phase (0-6 vol%) at moderate pressures (0.5-1.0 GPa) and temperatures (900-1300 °C). The composites are demonstrated to be highly tailorable with a range of compositions and resulting physical/mechanical properties. Ultrasonic measurements indicate that in some cases these composites have elastic mechanical properties that exceed those of the highest strength steel alloys. Two methods were identified to prevent phase transformation of the metastable cBN phase into hBN during consolidation: 1. removal of hydrocarbons, and 2. increased cBN particle size. Lithium tetraborate worked better as a binder than boron oxide, aiding consolidation without enhancing cBN to hBN phase transformation kinetics. These powder mixtures consolidated within error of their full theoretical mass densities at 1 GPa, and had only slightly lower densities at 0.5 GPa. This shows potential for consolidation of these composites into larger parts, in a variety of shapes, at even lower pressures using more conventional manufacturing methods, such as hot-pressing.

No abstract

No abstract

A high explosive pulsed power (HEPP) generator called the Advanced Helical Generator (AHG) has been designed, built, and successfully tested. The AHG incorporates design principles of voltage and current management to obtain a high current and energy gain.Its design was facilitated by the use of modern modeling tools as well as high precision manufacture. The result was a first-shot success. The AHG delivered 16 Mega-Amperes of current and 11 Mega-Joules of energy to a quasi-static 80 nH inductive load. A current gain of 154 times was obtained with a peak exponential rise time of 20 μs. We will describe in detail the design and testing of the AHG.

We have conducted three tests of a new pulsed power device called the full function test. These tests represented the culmination of an effort to establish a high energy pulsed power capability based on high explosive pulsed power (HEPP) technology. This involved an extensive computational modeling, engineering, fabrication, and fielding effort. The experiments were highly successful and a new U.S. record for magnetic energy was obtained.