It is common to divide hard materials into two groups: ultra-hard with
diamond and cubic boron nitride and a second group of hard materials
listed as SiC, TiC, etc. Between these two groups, a few ternary phase
s have a hardness overlapping that of cBN. We have perviously reported
on the synthesis of B-C-SI Si-O-C and Si-N-C crystalline phases. This
paper reports on crystalline silicon carbonitride phase-synthesized u
sing microwave plasmas with nitrogen or N-2-CH4-H-2 vapor etching sili
con. The crystalline phase possesses the pseudo-alpha-Si3N4 structure.
The microcrystals have a columnar form and an average size of 10 mu m
. The FTIR spectrum resembles that of alpha-Si3N4, but a set of new ab
sorption peaks appears. This new material is much harder than the Si3N
4 cutting tool insert, and it scratches single crystals of alpha-SiC,
sapphire and even the (001) surface of diamond. (C) 1998 Elsevier Scie
nce S.A. All rights reserved.