High speed sintering,a new powder-bed fusion additive manufacturing technology,utilizes infrared lights(IR)to intensely heat and melt polymer powders.The presence of defects such as porosity,which is associated with p...High speed sintering,a new powder-bed fusion additive manufacturing technology,utilizes infrared lights(IR)to intensely heat and melt polymer powders.The presence of defects such as porosity,which is associated with particle coalescence,is highly dependdent on the level of energy input.This study investigate the influcence of energy input on porosity and its subsequent effects on the mechanical properties and microstructures of PEBA parts.The parts were manufactured with a variety of lamp powers,resulting in a range of energy input levels spanning from low to high.Subsequebtly,they underwent testing using Archimedes’method,followed by tensile testing.The porosity,mechanical characteristics,and energy input exhibit a strong correlation;inadequate energy input was the primary cause of pore formation.Using the reduced IR light power resulted in the following outcomes:porosity,ultimate tensile strength,and elongation of 1.37%,7.6 MPa,and 194.2%,respectively.When the energy input was further increased,the porosity was reduced to as low as 0.05%and the ultimate tensile strength and elongation were increased to their peak values of 233.8%and 9.1 MPa,respectively.展开更多
A copper-catalyzed stereoselective 1,3-dipolar cycloaddition of methyleneindolinones and N,N0-cyclic azomethine imines has been developed under mild reaction conditions.The spiro[pyrazolidin-3,30-oxindoles] were obtai...A copper-catalyzed stereoselective 1,3-dipolar cycloaddition of methyleneindolinones and N,N0-cyclic azomethine imines has been developed under mild reaction conditions.The spiro[pyrazolidin-3,30-oxindoles] were obtained in moderate to high isolated yields（up to 82%） with good stereoselevtivities（up to 15：1） in the presence of 5 mol% of Cu（OAc）2at room temperature.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(No.52275333).
文摘High speed sintering,a new powder-bed fusion additive manufacturing technology,utilizes infrared lights(IR)to intensely heat and melt polymer powders.The presence of defects such as porosity,which is associated with particle coalescence,is highly dependdent on the level of energy input.This study investigate the influcence of energy input on porosity and its subsequent effects on the mechanical properties and microstructures of PEBA parts.The parts were manufactured with a variety of lamp powers,resulting in a range of energy input levels spanning from low to high.Subsequebtly,they underwent testing using Archimedes’method,followed by tensile testing.The porosity,mechanical characteristics,and energy input exhibit a strong correlation;inadequate energy input was the primary cause of pore formation.Using the reduced IR light power resulted in the following outcomes:porosity,ultimate tensile strength,and elongation of 1.37%,7.6 MPa,and 194.2%,respectively.When the energy input was further increased,the porosity was reduced to as low as 0.05%and the ultimate tensile strength and elongation were increased to their peak values of 233.8%and 9.1 MPa,respectively.
基金the National Natural Science Foundation of China (No.21172023)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and STD of Jiangsu Province for their financial supports
文摘A copper-catalyzed stereoselective 1,3-dipolar cycloaddition of methyleneindolinones and N,N0-cyclic azomethine imines has been developed under mild reaction conditions.The spiro[pyrazolidin-3,30-oxindoles] were obtained in moderate to high isolated yields（up to 82%） with good stereoselevtivities（up to 15：1） in the presence of 5 mol% of Cu（OAc）2at room temperature.
