Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational s...Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational speed of400r/min.For increasing the elongation,milled powders were mixed with30%and50%unmilled aluminum powder(mass fraction)with meanparticle size of>100μm and<100μm and then consolidated by hot pressing and hot extrusion with9:1extrusion ratio.Hot extrudedsamples were studied by optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),tensile and hardness tests.The results showed that mechanical milling process andpresence of B4C particles increase the yield strength of Al5083alloy from130to566MPa but strongly decrease elongation(from11.3%to0.49%).Adding<100μm unmilled particles enhanced the ductility and reduced tensile strength and hardness,but usingthe>100μm unmilled particles reduced the tensile strength and ductility at the same time.By increasing the content of unmilledparticles failure mechanism changed from brittle to ductile.展开更多
Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which pl...Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which plowing-extruding tool moved forward at two different feeds,f1 and f2,in turn.In this method,overlaps that are usually avoided in practical application were utilized to manufacture high fins and average height of fins was up to 1.58 mm.The critical feed(fc) of overlaps forming and terms of high fins forming were analyzed.The main technical parameters that affect the fins height were discussed.The experimental results show that the fins height increases with extruding inclination angle and plowing-extruding depth,and the fins height increases with f1 increasing when f1 is smaller than fc,and decreases with f1 increasing if f1 is larger than fc.展开更多
The present study reports investigations on rheological,mechanical,thermal,tribological and morphological properties of feedstock filaments prepared with polylactic acid-polyether ketone ketone-hydroxyapatite-chitosan...The present study reports investigations on rheological,mechanical,thermal,tribological and morphological properties of feedstock filaments prepared with polylactic acid-polyether ketone ketone-hydroxyapatite-chitosan(PLA-PEKK-HAp-CS)composite for 3D printing of functional prototypes.The study consists of a series of melt processing operations on melt flow index(MFI)setup as per ASTM D-1238 for melt flow certainty followed by fixation of reinforcement composition/proportion as 94%PEKK-4%HAp-2%CS(B)by mass in PLA matrix(A).The blending of reinforcement and preparation of feedstock filament for fused deposition modeling(FDM)set up has been performed on commercial twin screw extruder(TSE).The results of study suggest that feedstock filaments prepared with blend of 95%A-5%B(by mass)at 200℃processing temperature and 100 r/min rotational speed on TSE resulted into better tensile properties(35.9 MPa peak strength and 32.3 MPa break strength)with 6.24%surface porosity,42.67 nm surface roughness(R_(a))and acceptable heat capacity(2.14 J/g).However as regards to tribological behavior,the minimum wear of 316μm was observed for sample with poor tensile properties.As regards to crash application for scaffolds the maximum toughness of 1.16 MPa was observed for 85%A-15%B(by mass)at 200℃processing temperature and 150 r/min rotational speed on TSE.展开更多
文摘Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational speed of400r/min.For increasing the elongation,milled powders were mixed with30%and50%unmilled aluminum powder(mass fraction)with meanparticle size of>100μm and<100μm and then consolidated by hot pressing and hot extrusion with9:1extrusion ratio.Hot extrudedsamples were studied by optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),tensile and hardness tests.The results showed that mechanical milling process andpresence of B4C particles increase the yield strength of Al5083alloy from130to566MPa but strongly decrease elongation(from11.3%to0.49%).Adding<100μm unmilled particles enhanced the ductility and reduced tensile strength and hardness,but usingthe>100μm unmilled particles reduced the tensile strength and ductility at the same time.By increasing the content of unmilledparticles failure mechanism changed from brittle to ductile.
基金Project(50605023) supported by the National Natural Science Foundation of China
文摘Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which plowing-extruding tool moved forward at two different feeds,f1 and f2,in turn.In this method,overlaps that are usually avoided in practical application were utilized to manufacture high fins and average height of fins was up to 1.58 mm.The critical feed(fc) of overlaps forming and terms of high fins forming were analyzed.The main technical parameters that affect the fins height were discussed.The experimental results show that the fins height increases with extruding inclination angle and plowing-extruding depth,and the fins height increases with f1 increasing when f1 is smaller than fc,and decreases with f1 increasing if f1 is larger than fc.
基金Guru Nanak at Dev Engg. College, Ludhiana (GNDEC) and SERB (File No. IMRC/AISTDF/R&D/P-10/2017) for providing financial/technical assistance to carry out the research
文摘The present study reports investigations on rheological,mechanical,thermal,tribological and morphological properties of feedstock filaments prepared with polylactic acid-polyether ketone ketone-hydroxyapatite-chitosan(PLA-PEKK-HAp-CS)composite for 3D printing of functional prototypes.The study consists of a series of melt processing operations on melt flow index(MFI)setup as per ASTM D-1238 for melt flow certainty followed by fixation of reinforcement composition/proportion as 94%PEKK-4%HAp-2%CS(B)by mass in PLA matrix(A).The blending of reinforcement and preparation of feedstock filament for fused deposition modeling(FDM)set up has been performed on commercial twin screw extruder(TSE).The results of study suggest that feedstock filaments prepared with blend of 95%A-5%B(by mass)at 200℃processing temperature and 100 r/min rotational speed on TSE resulted into better tensile properties(35.9 MPa peak strength and 32.3 MPa break strength)with 6.24%surface porosity,42.67 nm surface roughness(R_(a))and acceptable heat capacity(2.14 J/g).However as regards to tribological behavior,the minimum wear of 316μm was observed for sample with poor tensile properties.As regards to crash application for scaffolds the maximum toughness of 1.16 MPa was observed for 85%A-15%B(by mass)at 200℃processing temperature and 150 r/min rotational speed on TSE.
