Polycrystalline diamond body prodn. - by epitaxially forming diamond-graphite coat on particles and sintering at high temp. and press.

摘要

Prodn. of polycrystalline diamond bodies by coating individual diamond particles with graphite, and sintering a suitable shaped agglomerate under pressure whereby the graphitic domains are converted into the diamond structure. The diamond-graphite coating is formed on the particles by epitaxial deposition. The subsequent heating and compressing of the agglomerate results in the formation of a strong compact body free of graphitic inclusions. The epitaxial deposition takes place in a stream of a carbon-contg. gas. The gas stream is stopped before a purely graphitic surface layer is formed. The initial deposit has the diamond structure; then a mixed layer is formed; and finally a purely graphitic structure. These bodies withstand dynamic loading, so that they can be used as drill heads, cutting edges of metal-working tools, metal wire-drawing dies, etc. The starting material may contain even very small particles (1 mu), in contrast to the known process.