Modification of Silicon Nitride Powders and Friction and Wear Properties of Ceramics at High Temperature

The effects of powder type, particle size, impurity content and phase composition of commercial silicon nitride powder on material properties were studied. Density, bending strength, thermal conductivity, friction and wear properties and microstructure of silicon nitride ceramics from different powders were examined. The silicon nitride powder treated with methanol modified liquid for 20 min led to silicon nitride ceramics with optimized comprehensive properties, including density of 3.16 g·cm⁻³, bending strength of (727±20) MPa, thermal conductivity of 71.6 W·m⁻¹·K⁻¹, friction coefficient between Si₃N₄ ceramics and C/SiC ceramics of < 0.7 at 1200 ℃. The ceramics exhibited strong high temperature resistance to friction and wear.