SOME PHYSICAL PROPERTIES OF POLYCRYSTALLINE SILICON BORIDE
Abstract
Silicon hexaborid and silicon tetraboride were synthesized, isolated from reac ion products, and fabricated into dense self-bonded structures. The physical properties of these polycrystalline structures were determined, including thermal expansion, thermal conductivity, electrical conductivity, oxidation resistance, transverse strength, modulus of elas icity nd icrohardness. Silicon tetraboride was synthesized by a solid state reaction of the elements in Ar at a temperature not exceeding 1300 C. Excess Si was removed by reaction wi Br gas and the purified powder fabricated into a dense body by hot pressing a prepressed section at 1350 C and 6000 psi for between 3 and 4 hours. Maximum density obtained was 2.08 g/cc. Silicon hexaboride was easily synthe ized by reactions similar to the tetraboride at temperatures of 1600 C or better. Excess Si was removed by treatment in very dilute hydrofluoric a d nitric acid solutions and th purified powder fabricated into a dense body by hot pressing a prepressed section at 1500 C and 6000 psi for 2 hours. A maximum density of 2.41 g/cc was obtained. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1962
- Accession Number
- AD0277686
Entities
People
- Robert S. Feigelson