Effect of sintering temperature and time on the microstructure, density, phase, selected mechanical and tribological properties of Cf/Si3N4 composite …

The purpose of this study is to examine the effect of different temperatures and sintering times on the microstructure, density, hardness, bending strength, coefficient of friction (COF), fracture toughness, and abrasion rate of Cf/Si3N4 fabricated via the spark plasma sintering (SPS) technique. For this target, the α phase of Si3N4 powder was prepared alongside sintering aids of alumina, yttria, and carbon fiber. Next, five samples were sintered via spark plasma sintering method at temperatures 1750 °C, 1800 °C, and 1850 °C, under the pressure of 70 MPa, and times of 10, 15, and 20 min. The obtained data illustrated that with an elevation of the sintering temperature from 1750 °C to 1850 °C, the density of the sintered body increased from 91.11% to 93.03%, and the hardness rose from 536 to 916 Vickers. Furthermore, upon prolonging the holding time from 10 min to 20 min, the density was enhanced from 93.03% to 96.53%, and hardness improved from 916 to 1433 Vickers. The results showed that with an elevation of temperature and time of sintering, the abrasion rate dropped from 14.4×10-7 to 4.4×10-7 g/N.m due to reducing the porosity of the sample. Finally, with a temperature rise from 1750 °C to 1850 °C, the bending strength of the samples decreased.