A Method for Preparing Electrically Conductive SiC Ceramics Through Hot-Press Sintering Followed by Nitrogen Pressure Heat Treatment

This paper demonstrates a novel method for preparing electrically conductive silicon carbide (SiC) ceramics by combining hot-press sintering and nitrogen pressure heat treatment. By incorporating graphite and AlN-Y2O3 sintering additives, conductive SiC ceramics with intergranular regions containing Y, C, and O elements were fabricated via low-temperature hot-pressing in a hot-press furnace. Following this, the samples were subjected to heat treatment in nitrogen atmosphere at varying temperatures using a gas pressure sintering furnace. It is revealed that Y and N elements were successfully dissolved into SiC grains, enhancing electrical conductivity. Additionally, localized nitridation occurred, and the Y2Si4CN6 phase—a newly identified phase in nitrided regions—was discovered for the first time, potentially contributing to reduced resistivity. After heat treatment, the sample resistivity decreased significantly from an initial 3.1 × 10−1 Ω·cm to the minimum of 7.56 × 10−3 Ω·cm.