黏性烧结过程的相场模拟  

Phase Field Simulation of Viscous Sintering

作　　者：郭松源 柳文波[1,2] 杨庆成 戚晓勇 恽迪 GUO Songyuan;LIU Wenbo;YANG Qingcheng;QI Xiaoyong;YUN Di(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology,Xi’an Jiaotong University,Xi’an 710049,China;Shanghai Key Laboratory of Mechanics in Energy Engineering,Shanghai University,Shanghai 200072,China)

机构地区：[1]西安交通大学能源与动力工程学院,西安710049 [2]西安交通大学陕西省先进核能技术重点实验室,西安710049 [3]上海大学上海市能源工程力学重点实验室,上海200072

出　　处：《金属学报》2024年第12期1691-1700,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金委员会与中国工程物理研究院联合基金(NSAF联合基金)项目No.U2130105;之江实验室科研攻关项目(No.2021PE0AC02);中国核工业集团有限公司领创科研项目。

摘　　要：为研究黏性烧结过程的组织形貌和物理性能的变化规律,本工作建立了黏性烧结过程的相场模型,分析了烧结颗粒的形貌、轴向速度场和压强场的演化结果。模拟结果表明:在表面张力驱动下,2个等大颗粒逐渐合并为1个圆形颗粒,演变过程中质量守恒;速度场在颗粒内部分为接触应变区域与刚体运动区域;颗粒内外压强差与颗粒曲率成正比关系。进一步分析发现,2个圆形颗粒的颈球比与收缩率在演化的开始阶段变化很大,符合黏弹性接触的规律;而在演化后期的变化较慢,此时2个圆形颗粒的颈球比与收缩率接近平衡状态的值;随着迁移率的增大,演化速率加快,但对稳定状态的形貌影响不大。多颗粒的模拟结果表明,黏性烧结过程中气孔会发生球化,随后缓慢消失,出现致密化;相同模拟条件下,尺寸较小的气孔演化速率更快。The presence of a liquid phase,which provides capillary force during viscous sintering,can accelerate the evolution of sintered particles.Due to the difficulty of coupling about the Navier-Stokes equations,however,it is quite challenging to obtain simulation results that meet the laws of physics.In the present study,a phase field model of the viscous sintering process is established,and the morphology,velocity field,and pressure field evolutions of the sintered particles are analyzed.First,the Cahn-Hilliard and Navier-Stokes equations are solved using the finite difference method and the predictor-corrector method.In the finite difference method,the upwind and central difference schemes are combined.The simulation results show that under the drive of surface tension,two circular particles gradually merge into one.The velocity field is divided into a pure straining region and a rigid body motion region inside the par-ticle;the pressure difference between the inside and outside of the particles is proportional to the curvature of the particles.Then,the contact radius and shrinkage of the two circular particles are calculated,and then a curve over time is drawn.The results show that they vary drastically at the beginning stage of evolution and satisfy the law of viscoelastic contact.In the later stage of evolution,the change becomes slower when the contact radius and shrinkage of the two circular particles are close to the values of the equilibrium state.With the increase in mobility,the evolution rate accelerates,but the morphology of the stable state is almost unchanged.The evolution of multiparticles and pores is also simulated.The results show that the pores in the viscous sintering process are initially spheroidized and then slowly disappear,resulting in densification.Under the same simulation conditions,the smaller pores evolve faster.

关 键 词：相场模拟 黏弹性接触 黏性烧结 气孔演化 

分 类 号：TG111.4[金属学及工艺—物理冶金]