Synthesis of New(W,Mo)(C,N) Powder by Heating W-Mo Alloy Powder in CH4+NH3 Mixed Gas of Normal-Pressure.

Abstract

The authors had already succeeded in synthesizing the powders of new tungsten and molybdenum mono-carbonitrides, i.e., W(C, N) and Mo(C, N), by the following two processes: (1) high-pressure process: heating of W+C and Mo+C mixed powder in N2 gas of 10-150 MPa at 1523-1773 K, and (2) normal-pressure process: heating of W and Mo powder in CH4+NH3 mixed gas of 0.1 MPa at 1373-1573 K. In this study, the synthesis of (W0.3Mo0.7) (C, N) was attempted by the latter normal-pressure process, i.e., by heating W-70at%Mo alloy+C mixed powder in NH3 gas (method I) and by heating the alloy powder in CH4+NH3 mixed gas (method II). It was found that (W0.3Mo0.7) (C, N) with nitrogen contents of 23-21 at% could be synthesized by method II at 1373-1573 K. The maximum nitrogen content was fairly larger than 5 at% of W(C, N) and 17 at% of Mo(C, N) synthesized by method II, and also larger than 16-21 at% of (W0.3Mo0.7)(C, N) synthesized by the high-pressure process at 10-150 MPa.