INTERACTION AND PHASE FORMATION IN THE WC–Fe₂O₃–NiO–С SYSTEM WHEN HEATED IN VACUUM AND ARGON

Abstract

The features of interaction and phase formation in the WC–33 wt.% (80 Fe₂O₃ + 20 NiO) system with and without free carbon when heated in vacuum and in an argon atmosphere are studied. Superfine soot and sucrose were used as free carbon. The powders pressed as pellets were heated by incremental temperature increase. In the absence of free carbon, carbon contained in WC and oxygen contained in Fe and Ni oxide actively interact in the carbide–oxide system, leading to weight loss of the samples. Intermetallic (Fe, Ni)₇W₆ phase, (Fe, Ni)WO₄ oxide, and W form as a result. Addition of free carbon allows WC to be retained partially or completely and Fe and Ni to be reduced from oxides. If there is a lack of free carbon, some part of carbon contained in WC begins to interact with oxygen to form complex Ме₆C carbide in the system and metal phase with fcc and bcc structures. When heating proceeds in vacuum, more carbon is spent to remove the same amount of oxygen than in heating in an argon atmosphere, but temperature of active interaction between carbon and oxygen decreases.