Multi-metal Influence On Tissue Forming And Mechanical Property Of Al₂O₃-Ti?C,N?

With the improvement of industrial production technology,the traditional die material has gradually cannot meet the demand.Due to its good mechanical properties,the Al₂O₃-Ti?C,N?based cermet has a wide application prospect in the field of die materials,but,as a ceramic material,its strength and toughness still has to be further improved.The experiment prepared Al₂O₃-Ti?C,N?based cermet material by vacuum hot-pressing sintering method,and researched the influence of the metal?Ta,V,Nb?and?Ni,Mo?content as well as hot-pressing process parameters on mechanical properties and microstructure of the Al₂O₃-Ti?C,N?based cermet materials,and it tests its thermal shock resistance and high temperature oxidation resistance.The main conclusion are as follows.?1?Adding Metal?Ta,V,Nb?and?Ni,Mo?to the Al₂O₃-Ti?C,N?based materials can effectively increase the material's mechanical properties.The right amount of metal additives can promote the densification degree of the material,refine the grain size and make material organization well-distributed,thereby enhancing the strength and toughness of the materials.In the process of sintering,the existence of liquid metals?Ni,Mo?can effectively reduce the sintering temperature and the holding time.?2?The sintering temperature and holding time are important process parameters in the sintering process of the ceramic material.The excessive low sintering temperature and the short holding time make an insufficient sintering process,more matrix porosity,the low densification degree of the materials and poor mechanical properties.Also,exorbitant temperature and long holding time will induce abnormal growth of the grains,and the existence of large grain will also reduce the material mechanics performance.?3?With the content of 7.5% metal?Ta,V,Nb?,the sintering temperature of 1700?,and the holding time of 30 min,Al₂O₃-Ti?C,N?-?Ta,V,Nb?cermet materials have the best mechanical properties.Its bending strength,hardness and fracture toughness respectively is 717 MPa,19.85 GPa and 6.24MP·am1/2,and the relative density is 98.87%.With the content of 7.5% metal?Ni,Mo?,the sintering temperature of 1650?,holding time of 25 min,Al₂O₃-Ti?C,N?-?Ni,Mo?cermet materials have the best mechanical properties.Its bending strength,hardness and fracture toughness is 834 MPa,19.22 GPa and 7.02MP·am1/2,respectively,and the relative density is 98.96%.?4?Adding metal?Ta,V,Nb?and?Ni,Mo?to the Al₂O₃-Ti?C,N?based materials can improve the material's inherent strength in different degrees,therefore,Al₂O₃-Ti?C,N?-?Ta,V,Nb?and Al₂O₃-Ti?C,N?-?Ni,Mo?cermet materials have better thermal shock resistance than Al₂O₃-Ti?C,N?composite material's.The bigger thermal shock temperature difference is,the more number of cracks exists in the material and the lower residual flexure strength the material has.The critical temperature difference of Al₂O₃-Ti?C,N?-?Ta,V,Nb?and Al₂O₃-Ti?C,N?-?Ni,Mo?cermet materials is 260? and 290?,respectively.?5?Al₂O₃-Ti?C,N?-?Ta,V,Nb?and Al₂O₃-Ti?C,N?-?Ni,Mo?cermet material have better high-temperature oxidation resistance.The material just has a slight oxidation reaction in 800?,and the residual flexural strength of the material is higher.At 1000?,the reaction becoming sharply and the oxidation products TiO2 forms a pyknotic oxidation film covering the surface of the materials.The existence of the oxide film can seriously reduce the material's flexure strength,but it also hinders the oxygen into the substrate,thereby slowing the further oxidation reaction.After 20 hours of oxidation at 1000?,the residual flexure strength of Al₂O₃-Ti?C,N?-?Ta,V,Nb?and Al₂O₃-Ti?C,N?-?Ni,Mo?cermet material is 352 MPa and 363 MPa,respectively.