Effect of the Particle Size of Conductive Inclusions on the Structurization and Resistivity of Si3N4–ZrC Ceramics

 
M.V.Soltis,
 
E.Kirilenko,
 
I.V.Zvorskii,
  

I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2012, #05/06
http://www.materials.kiev.ua/article/1037

Abstract

Heating elements with an active resistive layer composed of Si3N4 and 13.5 vol.% ZrC addition with the grain size varying from 1 to 46 μm are produced by hot pressing. The phase and grain-size composition and morphology of zirconium carbide grains are examined with X-ray diffraction, sedimentation analysis, and scanning electron microscopy. DC resistivity is studied by voltmeter–ammeter method in the temperature range between 20 and 600 ºС. It is established that different types of structure may form. These structures considerably differ in resistivity. The resistivity of the composites depends on the morphology of the conductive particles: on the specific surface area of the conductive particles and the effective cross-sectional area of the conductive cluster (resistivity increases by an order of magnitude with the transition from statistical to matrix structure). It is shown that the structure and resistivity of the material can be controlled by introducing a bimodal mixture of coarse and fine conductive particles. The matrix degree of the composite is evaluated by measuring its resistivity.


GRAIN SIZE OF CONDUCTIVE PARTICLES, MICROSTRUCTURE, NONDESTRUCTIVE MONITORING, PERCOLATION, RESISTIVITY, SILICON CARBIDE, ZIRCONIUM CARBIDE