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

摘要

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 deg C. The product is annealed in a second step at 2,000 deg 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 deg 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.