Preparation of Silicon Nitride Ceramics with High Wear Resistance by Aqueous Colloidal Process

Advanced silicon nitride ceramics with high wear resistance were fabricated by colloidal process.Orthogonal design was utilized to optimize the process parameters.The change of Zeta potential for Si_3N_4 particles after adding dispersant was analyzed.Furthermore,the microstructure,mechanical properties and wear resistance of silicon nitride ceramics were investigated.The results indicate that the green body with high density can be formed when the volume fraction of solid phase of silicon nitride slurry is equal to 45%.And silicon nitride ceramics with fracture toughness of 7.21MPa.m~(1/2),hardness of 9.30GPa is obtained in the optiinum condition.The friction and wear tests show that silicon nitride ceramics happen to crisp rupture and break off in the dry condition;while in the water-lubricated condition,the film of Si(OH)_4 is formed on the friction surface,and the wear mechanism is mainly chemical fretting wear.