Dependence of the resistivity of hot-pressed Si3N4–ZrC composites on their composition

Abstract

The paper examines the microstructure, phase composition, and resistivity of Si3N4-based composites depending on ZrC concentration and isothermal holding temperature. It is established that ZrCxNy forms in the composites during hot pressing. Its amount is determined only by isothermal holding temperature. It is shown that the resistivity and porosity of the composites depend not so much on the rate of chemical reactions as on the agglomeration of the starting powders when mixed. Addition of 10 to 20 vol.% zirconium carbide substantially changes the aggregation–disaggregation ratio. The reproducible resistivity of 0.5–10 Ω ∙ cm is reached. Thus these materials can be used as a resistive layer of small-size converters to perform under intensive heat exchange.