Influence of Fe<SUB>3</SUB>O<SUB>4</SUB> and Mo on Lipophilic Property of Silicon Nitride Ceramics

Si3N4 ceramics are often used as sliding parts in severe environments because of their properties of high hardness, light weight and superior abrasion resistance. Oil lubricant is applied to minimize their friction and wear. In addition to or instead of oil lubricant, lipophilic and self-lubricating materials and processes are being explored.In this study, Fe3O4 and Mo were added to Si3N4 to enhance the lipophilic properties and the abrasion resistance, while retaining strength. As a result, after adding Fe3O4 or Mo, the hardness, bending strength and density of Si3N4 ceramics decreased, while the lipophilic properties and abrasion resistance were enhanced. The lipophilic properties and abrasion resistance of Si3N4 ceramics after adding Fe3O4 and Mo were enhanced by either porosity or Fe3O4 on the material surface. The contact angle of macro-oil droplets became lower after adding Fe3O4, while the contact angle of micro-oil droplets remained almost the same.