Report of Research at Technische Universität Darmstadt on Ultrahard Materials in the B-C-N-Si System

Report No. ARL-CR-0774
Authors: Ralf Riedel; James W McCauley
Date/Pages: June 2015; 98 pages

There are 3 phases of this research program:

1) The synthesis of a boron carbide (B4C) ceramic powder by means of a polymer pyrolysis route. The synthesis involves the polycondensation of single molecules and subsequent thermal decomposition of the resulting boron-containing polymer at 1,100 °C. The product is annealed in a second step at 2,000 °C to form polycrystalline B4C. The work is divided into 3 parts: i) synthesis of the educts—namely, bis(trimethylsilyl)carbodiimide and 2,4,6-trichloroborazine; ii) synthesis of the preceramic polymer by reaction of the aforementioned educts; and iii) thermolysis of the polymer up to 2,000 °C in a helium atmosphere.

2) A comprehensive literature review on superhard materials and their method of fabrication, projected properties, and possible scale-up, with a focus on the B-C-N system.

3) Attempting to fabricate, using the multianvil press, larger samples of c-Si3N4 (transparent if possible)—a spinel structure material.

Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2015