以常见的废弃塑料制品组分高密度聚乙烯(PE-HD)、聚对苯二甲酸乙二醇酯(PET)为实验材料,设置两者的混杂比例为9/1、8/2和7/3,利用螺杆挤出机多次重复熔融再生,并利用体积脉动注塑成型工艺制备增强增韧的混杂塑料回收制品,实现多次回收...以常见的废弃塑料制品组分高密度聚乙烯(PE-HD)、聚对苯二甲酸乙二醇酯(PET)为实验材料,设置两者的混杂比例为9/1、8/2和7/3,利用螺杆挤出机多次重复熔融再生,并利用体积脉动注塑成型工艺制备增强增韧的混杂塑料回收制品,实现多次回收制品力学性能的显著提高。分析了不同注塑工艺对样品微观结构的影响机理,证明了体积脉动注塑成型引入的脉动应力场能有效提高不相容组分间的相容性,诱导掺杂相原位成纤和材料结晶形态的改变,构建互联杂化串晶结构。力学测试结果表明,在PE-HD和PET的混杂比例为9/1时,体积脉动注射成型制备的混杂回收材料屈服强度和冲击韧性达38.7 MPa和165 k J/m^(2),与稳态注射相比有54.8%和3675.7%的提升。混杂比例为7/3时,样品的屈服强度和冲击韧性为31.0 MPa和11.6 k J/m^(2),与稳态注射相比仍有14.8%和216.1%的提升。展开更多
A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional （3D） printing （AM/3DP） by n...A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional （3D） printing （AM/3DP） by numerical simulation, using a finite volume method （FVM）. The influence of the applied linear energy density （LED） on dimensions of the molten pool, thermodynamic mechanisms within the pool, bubbles migration and resultant densification behavior of AM/3DP-processed superalloy has been discussed. It reveals that the center of the molten pool slightly shifts with a lagging of 4 ktm towards the center of the moving laser beam. The Mar- angoni convection, which has various flow patterns, plays a crucial role in intensifying the convective heat and mass transfer, which is responsible for the bubbles migration and densification behavior of AM/3DP-processed parts. At an optimized LED of 221.5 J/m, the outward convection favors the numerous bubbles to escape from the molten pool easily and the resultant considerably high relative density of 98.9 % is achieved. However, as the applied LED further increases over 249.5 J/m, the convection pattern is apparently intensified with the formation of vortexes and the bubbles tend to be entrapped by the rotating flow within the molten pool, resulting in a large amount of residual porosity and a sharp reduction in densification of the superalloy. The change rules of the relative density and the corresponding distribution of porosity obtained by experiments are in accordance with the simulation results.展开更多
文摘以常见的废弃塑料制品组分高密度聚乙烯(PE-HD)、聚对苯二甲酸乙二醇酯(PET)为实验材料,设置两者的混杂比例为9/1、8/2和7/3,利用螺杆挤出机多次重复熔融再生,并利用体积脉动注塑成型工艺制备增强增韧的混杂塑料回收制品,实现多次回收制品力学性能的显著提高。分析了不同注塑工艺对样品微观结构的影响机理,证明了体积脉动注塑成型引入的脉动应力场能有效提高不相容组分间的相容性,诱导掺杂相原位成纤和材料结晶形态的改变,构建互联杂化串晶结构。力学测试结果表明,在PE-HD和PET的混杂比例为9/1时,体积脉动注射成型制备的混杂回收材料屈服强度和冲击韧性达38.7 MPa和165 k J/m^(2),与稳态注射相比有54.8%和3675.7%的提升。混杂比例为7/3时,样品的屈服强度和冲击韧性为31.0 MPa和11.6 k J/m^(2),与稳态注射相比仍有14.8%和216.1%的提升。
基金supported by the National Natural Science Foundation of China (51575267, 51322509)the Top-Notch Young Talents Program of China+9 种基金the Outstanding Youth Foundation of Jiangsu Province of China (BK20130035)the Program for New Century Excellent Talents in University (NCET-13-0854)the Science and Technology Support Program (the Industrial Part)Jiangsu Provincial Department of Science and Technology of China (BE2014009-2)the 333 high-level talents training project (BRA2015368)the Science and Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Human Resources and Social Security of Chinathe Aeronautical Science Foundation of China (2015ZE52051)the Shanghai Aerospace Science and Technology Innovation Fund (SAST2015053)the Fundamental Research Funds for the Central Universities (NE2013103, NP2015206 and NZ2016108)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A mesoscopic model has been established to investigate the thermodynamic mechanisms and densification behavior of nickel-based superalloy during additive manufacturing/three-dimensional （3D） printing （AM/3DP） by numerical simulation, using a finite volume method （FVM）. The influence of the applied linear energy density （LED） on dimensions of the molten pool, thermodynamic mechanisms within the pool, bubbles migration and resultant densification behavior of AM/3DP-processed superalloy has been discussed. It reveals that the center of the molten pool slightly shifts with a lagging of 4 ktm towards the center of the moving laser beam. The Mar- angoni convection, which has various flow patterns, plays a crucial role in intensifying the convective heat and mass transfer, which is responsible for the bubbles migration and densification behavior of AM/3DP-processed parts. At an optimized LED of 221.5 J/m, the outward convection favors the numerous bubbles to escape from the molten pool easily and the resultant considerably high relative density of 98.9 % is achieved. However, as the applied LED further increases over 249.5 J/m, the convection pattern is apparently intensified with the formation of vortexes and the bubbles tend to be entrapped by the rotating flow within the molten pool, resulting in a large amount of residual porosity and a sharp reduction in densification of the superalloy. The change rules of the relative density and the corresponding distribution of porosity obtained by experiments are in accordance with the simulation results.
