JIANG Yong, HUANG Xinhua, WU Lan'er, LU Youjun
(Beifang University of Nationalities, Yinchuan 750021, Ningxia, China)
Abstract: Si3N4-TiZrN2-TiN electric ceramic composite was prepared by pressless sintering at 1750 ℃ with Y2O3, La2O3 and AlN as sintering additives and ZrN-TiN as electric phases. The sintering behavior, mechanical and electric properties of the composite were tested. The phase composition and microstructure of the composite were analyzed by XRD and SEM. The result shows that its relative density reaches 98%, its bending strength 960 MPa, its Vickers hardness 14.7 GPa, and its fracture toughness 7.6 MPa·m1/2. The electric resistivity of the samples decreases to as low as 10-2 Ω·cm from 1013 Ω·cm of single phase Si3N4. It makes electrical discharge machining of the composite possible. Phase composition analysis result shows a new phase of TiZrN2 is formed in the samples and Si3N4-TiZrN2-TiN composite conductive ceramic is produced. The grains are less than 2 μm, and the samples have a microstructure in which the TiZrN2, TiN and Si3N4 grains are closely bonded to each other and uniformly distributed.
Key words: Si3N4-TiZrN2-TiN; conductive ceramic composite; conductive phase; resistivity