Febrication And Properties Of Graded Nano-composite Ceramic Tool Materials

By introducing functionally graded composite into Nano-composite ceramic tool material,an Al₂O₃/TiCN graded Nano-composite ceramic tool material was fabricated successfully.The mechanical properties,microstructure and fracture extension pattern of the ceramics were studied.Thermal shock resistance and cutting process were studied by FEM.By cutting AISI316L,cutting performance and fool failure mechanisms were detailed studied.When the volume fractions of Al₂O₃,TiCN,MgO and NiO are 54%,45%,5%and 5%,Al₂O₃/TiCN graded Nano-composite ceramic with strength of 810 MPa,hardness of 19.5GPa and touchness of 6.6 MPa·m^1/2 can be obtained by hot-press sintering under the temperature of 1650℃,pressure of 30MPa and holding time of 10 minutes.The microstructure of the Al₂O₃/TiCN graded Nano-composite ceramic is mainly characterized by transgranular fracture;the crack deflection,crack bridging and crack branching in the crack extension path also contribute to the improvement of mechanical properties.Thermal shock resistance of Al₂O₃/TiCN graded Nano-composite ceramic was simulated using ANSYS.The influence of Layer-thickness ratio and compositional distribution on thermal shock resistance were analyzed,and consequently the graded structure parameters were optimited.The cutting process of Al₂O₃/TiCN graded Nano-composite ceramic tool when machining AISI316L was simulated by DEFORM-2D.The influences of cutting speed on cutting temperature field,thermal stress field and cutting force were studied.With the speed increased,the tool temperature is higher.Compared with homogeneous ceramic tools,it has good thermal shock resistance.With the speed increased,tool stress also increased,the tool stress is lower than homogeneous ceramic tools at high cutting speeds.The cutting force decreased with the speed increased,which is equvilent to that of other ceramic tools.As for the maching of AISI316L steel,cutting force,temperatue,tool failure mechanisms of Al₂O₃/TiCN graded Nano-composite ceramic tool were studied.The cutting force decreased and temperature increased with the speed increased. Al₂O₃/TiCN graded Nano-composite ceramic tool has longer life than other ceramic tools under the same condition.The main failure mode is rake wear,flank wear and spalling when speed is low,because of abrasive and mechanical fatigue.The main failure mode is rake wear,flank wear and notch wear when speed is high,because of abrasive and adhesive.