Preparation Of Surface Texture And Its Effect On Tribological Properties Of RGO/TZ3Y20A Composite

Ceramic materials,as the most promising materials in the field of artificial joints,have been widely concerned owing to their high hardness,good corrosion resistance and wear resistance.Strengthening and toughening materials,exploiting the function of surface texture to further improve the performance of ceramic matrix composites,which has important significance for promoting the application of composite materials in the field of artificial joints.The ceramic powders ZrO₂?3 mol.%Y₂O₃?-20 wt.%Al₂O₃?TZ3Y20A?was selected as the matrix material.When sintered at 1600 °C,the hardness of TZ3Y20 A ceramic is 15.48 GPa,flexural strength is 1188 MPa and fracture toughness is 15.2 MPa·m1/2.The RGO/TZ3Y20 A composite was prepared by adding the graphene oxide into the ceramic powder and sintered at 1450 °C.With the increase of graphene oxide content,the density of the composites decreased,but the hardness,bending strength and fracture toughness increased first and then decreased.The best mechanical properties of composites are achieved when the graphene oxide content is 0.5%,which the hardness is 17.75 GPa,flexural strength is 1300 MPa,and fracture toughness is 17.6 MPa·m1/2.The morphologies of the dimples were regularly machined on the TZ3Y20 A ceramic and RGO/TZ3Y20 A composites by laser drilling.The dimple is 90 ?m in diameter,25 ?m in depth,and the dimples pitch is 300 ?m,200 ?m and 140 ?m,which the corresponding texture density were 7%,16% and 33%,respectively.Grinding with alumina under 4.9 N load,TZ3Y20 A ceramic with 33% texture density has lower of friction coefficient and wear rate.Under the load of 9.8 N,the morphology of the dimples was destroyed and the effect of surface texture to reduce the friction coefficient was decreased.Grinding with stainless steel,the friction coefficient of TZ3Y20 A ceramics with 33% texture density decreased 34% at 4.9 N load and 29% at 9.8 N load,compared with none texture ceramics.Grinding with UHMWPE under the 100 N load,the friction coefficient of ceramics is between 0.25 and 0.27,the surface texture loses the effect of decreasing the friction coefficient of ceramics.Grinding with alumina,the friction coefficient and wear rate of the composite with 0.5 wt.% graphene decreased with the increase of the texture density.Under 4.9 N load,the friction coefficient of the composite with 33% texture density is 0.67.and wear rate is 0.78×10-6 mm3/Nm.While under 9.8 N load,the friction coefficient is 0.65,and wear rate is 1.76×10^-6 mm³/Nm.The composite has a lower friction coefficient and wear rate than that of TZ3Y20 A ceramics.The graphene in composites enhances the fracture toughness of the material by pulling out,bridging and deflecting the crack,and improves the wear resistance of the composite materials by reducing the brittle fracture.The surface texture will trap the wear debris during the friction process and reduce the accelerated wear due to the abrasive to bring a stable friction process.