Numerical Simulation Of Hot Pressing Sintering Process Of Ceramic Tool Materials

In recent decades,high-speed cutting technology has been successfully applied to the cutting process of metals and their alloy materials in high-precision manufacturing fields such as aerospace,automobile manufacturing,and high-speed rail and ships,due to their high production efficiency and good processing quality.Because of the extremely high speed of high-speed cutting,it is easy to form heat accumulation and cause local wear of the tool.Therefore,higher requirements are placed on the mechanical properties of the tool material.Based on this,researchers at home and abroad have studied and developed a variety of new tool materials suitable for high-speed cutting.With its good mechanical properties and excellent cost performance,ceramic tools have shown the irreplaceable advantages of traditional tools in the field of high-speed cutting.However,the ceramic tool materials currently prepared by hot-press sintering cannot fully meet people’s performance requirements.In addition,the ceramic tool materials prepared by hot-press sintering are also prone to uneven sintering,low density,excessive thermal stress and micro cracks and other defects.To this end,this article takes Al₂O₃-Ti C-Co multi-phase ceramic tool material as an example,through the analysis of the main factors affecting the hot pressing sintering process,the temperature field of the ceramic green body during the hot pressing sintering process is numerically simulated,and on the basis of this,the numerical simulation of the formation of residual stress during the hot-press sintering densification process and cooling process is carried out,and the suitable process parameters are determined.The main contents of this research are as follows:（1）The densification process of hot-press sintering is studied,and its main factors affecting hot-press sintering are analyzed.Combining the characteristics of powder materials,the principle is elaborated from the aspects of yield condition,flow rule and constitutive equation,and the theoretical formula of the thermo-elastic plastic deformation constitutive model;based on the characteristics of the hot-press sintering process,the iterative relationship between the temperature conduction equation and the stress-strain equation of the thermal-structure coupling analysis is analyzed.（2）Aiming at the complex heat transfer problem in the hot press sintering process,the theoretical equations of heat radiation and heat conduction process are built;the temperature field distribution of the ceramic tool material during hot press sintering process is simulated using finite element software,and different initial porosity.The influence of heating rate,holding time and heat insulation layer on the temperature field distribution of the ceramic body during the hot pressing sintering process determines the appropriate heating rate and holding time,and improves the overall temperature and sintering uniformity of the ceramic body.（3）According to the characteristics of the powder deformation mechanism in the hot press sintering process,the finite element software is used to simulate the densification process of the ceramic powder in the hot press sintering process,revealing the flow law of the ceramic powder during the hot press sintering process;the influence of pressure and holding time on the density of ceramic powder during the sintering process;determining the appropriate sintering pressure and holding time provides a certain theoretical basis for the optimization of the parameters of the sintering process.（4）Combined with the actual cooling process,a theoretical model of the thermal stress of the ceramic tool material in the cooling process is constructed;by establishing a finite element model of the cooling process of the sintering furnace,the temperature gradient distribution and residual stress distribution of the ceramic tool material in the cooling process are studied;The comparison of two material models analyzes the reasons for the formation of residual stress in the cooling process,and studies the distribution of residual stress in the ceramic body.The numerical simulation method of the hot pressing sintering process of ceramic tool materials based on the finite element theory has the advantage that it can overcome the defects of traditional experimental methods that cost a lot of manpower and material resources,and realize the sintering prediction and parameter optimization of different material properties.Sintering process optimization provides theoretical guidance.