Study On The Preparation And Performance Of Ceramic Cutting Tools Based On High Temperature Mechanical Behavior

Nickel-based superalloy GH4169 still has good mechanical properties,excellent oxidation resistance and corrosion resistance at high temperature of 1000℃,which has become an irreplaceable key material for hot end components of military and civil energy conversion devices.However,its poor machinability always restricts the efficient production of high-performance parts.The reason is that the tool is difficult to adapt to the strong thermal chemical multi field coupling environment in high-speed cutting of nickel base superalloy,which is manifested as short tool life,poor machining quality and low machining efficiency.Therefore,based on the high-speed cutting of nickel-based superalloy GH4169,this paper studies the relationship between high-temperature mechanical properties,cutting performance and tool failure mechanism of ceramic cutting tools,designs and optimizes the new ceramic cutting materials and their preparation process.Combined with simulation experiments,a new type of ceramic tool with excellent high temperature mechanical properties suitable for machining nickel-based superalloy GH4169 was developedIn this paper,nickel-based superalloy GH4169 was taken as the cutting object.Firstly,the high-speed cutting experiments were carried out with three kinds of domestic ceramic cutting tools of CC,SN2 and CJ,and their cutting parameters were optimized.During the cutting process,infrared thermal imaging cameras and Kistler 9257B dynamic dynamometer were used to test the cutting force and temperature in the cutting area.The high-temperature hardness test system HTV-PHS30 was used to test the variation trends of hardness and fracture toughness of different brands of cutting tools with temperature and the evolution mechanism was analyzed.Then the failure mechanism of ceramic cutting tools with different material components was studied.The research shows that the material and cutting amount of the tool will affect the failure form and failure mechanism of the tool;the failure form of the CC ceramic tool with the best cutting performance is micro chipping,flank wear,and severe boundary groove wear.The failure mechanism is severe adhesive wear,slight abrasive wear and oxidation wear at the tipBased on the evolution of high-temperature mechanical behavior of three grades of ceramic tools and the failure mechanism of high-speed cutting superalloy GH4169,a design principle for the material composition of high-performance cutting tools for nickel-based superalloy GH4169 was proposed.And based on the theory of synergistic toughening,the advanced AWN ceramic cutting tool material was designed with Al2O3 as the matrix,SiCw and Si3N4 as the reinforcing phases,and Y2O3,La2O3,CeO2(YLC)as the sintering aidsThe powder mixing process of AWN composite ceramic materials was studied.The results show that the dispersion of whiskers and the uniform mixing with micro-nano particles play a vital role in the excellent performance of AWN ceramic materials Through optimized experimental research,a powder mixing process capable of overcoming the intertwining of whiskers and agglomerating particles was proposedThe effects of Si3N4 particle content and sintering process on the comprehensive properties of AWN ceramic materials were studied,and the synergistic toughening and strengthening mechanism of SiC whiskers and Si3N4 particles was studied.Based on the feedback of the microstructure and mechanical properties of AWN ceramic materials,further adjustments were made.The component content and the sintering process were optimized.The advanced AWN 15 tool material with low-defect and high-performance was sintered under a pressure of 32 MPa and a temperature of 1600℃ in vacuum for 30 min.The optimized densities,Vickers hardness,fracture toughness,flexural strength and fracture toughness of the new AWN15 ceramic materials at room temperature are 99.2 ±0.15%,18.2 ± 0.16 GPa,769± 22 MPa,and 6.78 ± 0.12 MPa·m1/2,respectively.The fracture toughness of AWN15 composite ceramic materials were effectively enhanced due to the cooperative toughening mechanism of SiCw and Si3N4,crack deflection,whisker bridging cracks,whisker pull-out,transgranular fracture and microcrack generation.The mechanical properties and microstructure of AWN15 ceramic cutting tool material with temperature were studied and the evolution mechanism was studied.The results show that the decrease tendency of the hardness and fracture toughness of AWN 15 composite ceramic materials with increasing temperature slowed down significantly.And when the test temperature reached 1000℃,the hardness and fracture toughness can maintain more than 65%of that at room temperature.The reason is that the addition of Si3N4 particles is beneficial to reduce the temperature sensitivity of AWN15 ceramic materials,stabilize the Vickers hardness and fracture toughness at high temperature,and help improve the high-temperature wear resistance of AWN15 ceramic tools and increase the resistance to breakage.The mechanical properties of AWN 15 ceramic materials were weakened due to the defects inside the material caused by high temperature and the decrease of the grain boundary strength,and the plastic deformation that occurs after the material softens can alleviate the deterioration of the high temperature fracture toughness to a certain extentThe cutting process of AWN 15 ceramic tool for high-speed machining of nickel-based superalloy GH4169 was studied.The tool geometry and tool working angle were optimized,and the cutting amount was planned.According to the simulation analysis of high-speed cutting of GH4169 with alumina-based ceramic tools,the reasonableness of the established finite element model is verified,and the feasibility of AdvantEdge software to guide the research on the performance of AWN15 new ceramic tools is verified.A small chamfer width(0.1 mm)and a reasonable rake angle(-6°)were determined to improve the stress and temperature field distribution in the working area of the tool.The cutting parameters of the high-speed turning of nickel-based superalloy GH4169 by AWN15 new ceramic tool were optimized,that is,the cutting speed ≤180 m/min and the feed speed<0.14 mm/r.