微注射成形与微波烧结的实验和模拟研究
发布时间：2023-05-28 10:50
粉末注射成形过程包括四个阶段：混料、注射、脱脂和烧结。本论文主要对微注射成形和微波烧结两个工艺过程展开研究：修正和补充了用于模拟注射填充过程的数值算法；实现表面张力效应的计算与评估；以17-4PH不锈钢粉末成形件为样品进行微波烧结实验研究；在微波加热和热传导模拟的基础上,补充粉末材料的烧结致密化模型,实现了微波烧结多物理场耦合现象的数值模拟。为提高注射成形过程数值模拟结果的准确性,本论文修改和补充了用于注射填充过程的全矢量显式模拟算法。针对填充流在复杂形状模腔中流向失真的问题,本论文采用类似迎风法的概念,修正了空气流动速度场对填料填充的不真实影响,有效抑制了填充流向的失真现象。建议了补充合理边界条件的数值方法,修正不可压缩流体在填充末段出现的非线性填充延迟现象,并验证了该方法的有效性。为了拓展研究组内自行开发的有限元模拟软件,使其适用于模拟微注射成形问题,本论文在原有注射成形模拟算法的基础上,实现了表面张力计算和模拟功能。由于没有针对有限元法的适当算法,本文建议并实施了一种系统化操作的算法,实现了填充前沿面曲率的计算,进而求解得到表面张力值。应用植入表面张力功能的软件,模拟了一系列典型...
【文章页数】：157 页
【学位级别】：博士
【文章目录】：
摘要
Abstract
Resume
Glossary
Nomenclature
Introduction
Chapter 1 State of the art
1.1 Brief introduction of PIM
1.2 The advantages of PIM
1.3 PIM development and market
1.4 The principal research centers in PIM processing
1.5 Researches on PIM process in France and in China
Chapter 2 Developments of modified algorithms for Mold Filling Process
2.1 Modeling and Simulation of PIM injection
2.1.1 General Definition
2.1.2 Governing Equations
2.1.3 Explicit algorithm for simulation
2.2 Algorithm for improvement of wrongly adverted filling profile
2.2.1 The source for distorted simulation results
2.2.2 Modification of the solution procedure
2.2.3 Validation of the modification scheme
2.2.4 Conclusion
2.3 The outlet condition in simulation of MIM injection to track the end of filling process
2.3.1 The inexact result at the end of filling process
2.3.2 Modification of the outlet boundary condition
2.3.3 Validation of the modified algorithm
2.3.4 Conclusion
Chapter 3 Numerical method and analysis for surface tension effects in micro-injectionprocess
3.1 Mechanical modeling
3.2 Surface tension force
3.3 Implementation of Surface tension in FEM
3.3.1 Surface curvature computation
3.3.2 Surface tension force in computation
3.4 Numerical investigation and discussion
3.5 Conclusion
Chapter 4 Brief Introduction and Foundational Theories for Sintering
4.1 Introduction of sintering
4.1.1 Berif introduction of sintering
4.2 Foundational Theories for Sintering
4.2.1 Driving Forces of Sintering
4.2.2 Sintering Mechanisms
4.2.3 Stages of Sintering
4.3 Models and Simulations of Sintering
4.3.1 Simulation history
4.3.2 Three sintering models
Chapter 5 Efficient sintering of 17-4PH stainless steel powder by microwave
5.1 Research background
5.2 Experimental procedure
5.3 Results and discussion
5.3.1 Specimen sizes after being injected, debinded and MW sintered
5.3.2 The influence factors in MW sintering process
5.3.3 Microstructure
5.3.4 Distribution of the Vickers-hardness
5.3.5 Comparison with the conventional sintering
5.3.6 Conclusions
Chapter 6 Mathematical Modeling and Simulation of Microwave Sintering Process
6.1 Research Background
6.2 Mathematical model of microwave sintering
6.2.1 Solve Maxwell equation to get electromagnetic fields in cavity of the furnace
6.2.2 Solve for distribution of the heat generation in process of microwave sintering
6.2.3 Solution of heat transfer equation to get temperature field in the sintered body
6.2.4 Solve the governing equations of sintering densification to get the structural response of sintered body
6.2.5 Coupling of the Maxwell equation, heat transfer equation and mechanic equations
6.3 Numerical simulation of microwave sintering process
6.3.1 Modeling of Microwave Sintering
6.3.2 Numerical analysis
6.4 Conclusion and outlook
Chapter 7 Conclusions and Perspectives
7.1 Conclusions
7.2 Future Work
Acknowledgement
References
Publications
本文编号：3824446
【文章页数】：157 页
【学位级别】：博士
【文章目录】：
摘要
Abstract
Resume
Glossary
Nomenclature
Introduction
Chapter 1 State of the art
1.1 Brief introduction of PIM
1.2 The advantages of PIM
1.3 PIM development and market
1.4 The principal research centers in PIM processing
1.5 Researches on PIM process in France and in China
Chapter 2 Developments of modified algorithms for Mold Filling Process
2.1 Modeling and Simulation of PIM injection
2.1.1 General Definition
2.1.2 Governing Equations
2.1.3 Explicit algorithm for simulation
2.2 Algorithm for improvement of wrongly adverted filling profile
2.2.1 The source for distorted simulation results
2.2.2 Modification of the solution procedure
2.2.3 Validation of the modification scheme
2.2.4 Conclusion
2.3 The outlet condition in simulation of MIM injection to track the end of filling process
2.3.1 The inexact result at the end of filling process
2.3.2 Modification of the outlet boundary condition
2.3.3 Validation of the modified algorithm
2.3.4 Conclusion
Chapter 3 Numerical method and analysis for surface tension effects in micro-injectionprocess
3.1 Mechanical modeling
3.2 Surface tension force
3.3 Implementation of Surface tension in FEM
3.3.1 Surface curvature computation
3.3.2 Surface tension force in computation
3.4 Numerical investigation and discussion
3.5 Conclusion
Chapter 4 Brief Introduction and Foundational Theories for Sintering
4.1 Introduction of sintering
4.1.1 Berif introduction of sintering
4.2 Foundational Theories for Sintering
4.2.1 Driving Forces of Sintering
4.2.2 Sintering Mechanisms
4.2.3 Stages of Sintering
4.3 Models and Simulations of Sintering
4.3.1 Simulation history
4.3.2 Three sintering models
Chapter 5 Efficient sintering of 17-4PH stainless steel powder by microwave
5.1 Research background
5.2 Experimental procedure
5.3 Results and discussion
5.3.1 Specimen sizes after being injected, debinded and MW sintered
5.3.2 The influence factors in MW sintering process
5.3.3 Microstructure
5.3.4 Distribution of the Vickers-hardness
5.3.5 Comparison with the conventional sintering
5.3.6 Conclusions
Chapter 6 Mathematical Modeling and Simulation of Microwave Sintering Process
6.1 Research Background
6.2 Mathematical model of microwave sintering
6.2.1 Solve Maxwell equation to get electromagnetic fields in cavity of the furnace
6.2.2 Solve for distribution of the heat generation in process of microwave sintering
6.2.3 Solution of heat transfer equation to get temperature field in the sintered body
6.2.4 Solve the governing equations of sintering densification to get the structural response of sintered body
6.2.5 Coupling of the Maxwell equation, heat transfer equation and mechanic equations
6.3 Numerical simulation of microwave sintering process
6.3.1 Modeling of Microwave Sintering
6.3.2 Numerical analysis
6.4 Conclusion and outlook
Chapter 7 Conclusions and Perspectives
7.1 Conclusions
7.2 Future Work
Acknowledgement
References
Publications
本文编号：3824446
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