Additive manufacturing is a new emerging technology which is ideal for low-to-zero waste production, and it is considered to be a green and clean process that has the potential to lower the cost and energy consumption...Additive manufacturing is a new emerging technology which is ideal for low-to-zero waste production, and it is considered to be a green and clean process that has the potential to lower the cost and energy consumption of production. However, the cost of the feedstock for additive manufacturing and the additive manufactured parts is usually very high, which hinders the further application of additive manufacturing, especially for the metal additive manufacturing. The concept of circular metal additive manufacturing involves the recycling of the metal feedstock and the additive manufactured parts leading to the truly zero waste production and the most energy saving. This paper reviews the technologies that help the formation of a circular metal additive manufacturing through recycling of the feedstocks and the damaged metal parts. Reactive metals, such as titanium, tend to be contaminated easily during handling and production. Recycling of the titanium for achieving a circular titanium additive manufacturing is reviewed in detail.展开更多
Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO_(2),V_(2)O_(5) and Al_(2)O_(3) in this study.The oxide mixture was first reduced by Mg in MgCl_(2) at 750℃ in argon,where oxygen wa...Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO_(2),V_(2)O_(5) and Al_(2)O_(3) in this study.The oxide mixture was first reduced by Mg in MgCl_(2) at 750℃ in argon,where oxygen was reduced to 2.47 wt%from 40.02 wt%.The oxygen content in the final powder was eventually reduced to an extremely low level(0.055 wt%)using calcium at 900℃ in argon,and the final powder had the composition of 90.12 wt%Ti,5.57 wt%Al,and 3.87 wt%V,which meets the standard specification of Ti-6Al-4V(ASTM F1108-09).Between the two reductions,a heat treatment step was designed to help controlling the specific surface area and particle size.The effect of the heat treatment temperature on the morphology,and composition uniformity of the powder was investigated in detail.Heat treatment above 1300℃ attributed to a dense powder with a controlled specific surface area.Thermodynamic modeling and experimental results indicated that onlyα-Ti enriched with Al andβ-Ti enriched with V exist in the final powder,and other possible phases including Al-Mg and Al-V were excluded.This study also offers a triple-step thermochemical process for producing high-purity Ti-based alloy powder.展开更多
A high-purity Ti-48Al-2Nb-2Cr alloy powder with an oxygen content as low as 0.0572 wt.%and a particle size of<150μm was produced from a mixture of TiO_(2),Al_(2)O_(3),Nb_(2)O_(5),and Cr_(2)O_(3)powders through red...A high-purity Ti-48Al-2Nb-2Cr alloy powder with an oxygen content as low as 0.0572 wt.%and a particle size of<150μm was produced from a mixture of TiO_(2),Al_(2)O_(3),Nb_(2)O_(5),and Cr_(2)O_(3)powders through reduction with magnesium and deoxidation with calcium.The phase and composition of the products were analyzed.The final product mainly includedγ-TiAl and minorα_(2)-Ti_(3)Al phases,and Ti,Al,Cr,and Nb were homogenously distributed in the powder with a mole ratio of 49.73:43.51:2.05:1.98.The reduction and deoxidation mechanisms were investigated by thermodynamic modeling using the HSC Chemistry software and Pandat software based on the Ti alloy database.展开更多
A direct production method of high-strength titanium alloy from upgraded titania slag(UGS)was developed.First,UGS was reduced into alloy powder with 1.3 wt.%oxygen using magnesium powder.Subsequently,the alloy powder ...A direct production method of high-strength titanium alloy from upgraded titania slag(UGS)was developed.First,UGS was reduced into alloy powder with 1.3 wt.%oxygen using magnesium powder.Subsequently,the alloy powder was compacted at 600 MPa to produce a pellet.Lastly,the pellet was sintered to produce titanium alloy.The reduced powder was characterized,and the effect arising from the sintering temperature on the sintered density,compressive strength,microstructure,and hardness of the alloys was studied.The results showed that the density tended to increase with the temperature increasing from 900 to 1200℃,whereas the porosity decreased.A significant sintering densification was achieved at the temperature above 1100℃(98.65%at 1100℃ and 99.41%at 1200℃).At 1100℃,the hardness and compressive strength reached the maximal values of the alloy,HV 655.7 and 1563 MPa,respectively.展开更多
基金the National Natural Science Foundation of China(No.52004342)Innovation-driven Project of Central South University,China(No.150240015)Natural Science Fund for Outstanding Young Scholar of Hunan Province,China(No.2021JJ20065).
基金Project(52004342)supported by the National Natural Science Foundation of ChinaProject(150240015)supported by the Innovation-driven Project of Central South University,ChinaProject(2021JJ20065)supported by the Natural Science Fund for Outstanding Young Scholar of Hunan Province,China。
基金Project(51922108)supported by the National Natural Science Foundation of ChinaProject(2019JJ20031)supported by Hunan Natural Science Foundation,ChinaProject(2019SK2061)supported by Hunan Key Research and Development Program,China。
文摘Additive manufacturing is a new emerging technology which is ideal for low-to-zero waste production, and it is considered to be a green and clean process that has the potential to lower the cost and energy consumption of production. However, the cost of the feedstock for additive manufacturing and the additive manufactured parts is usually very high, which hinders the further application of additive manufacturing, especially for the metal additive manufacturing. The concept of circular metal additive manufacturing involves the recycling of the metal feedstock and the additive manufactured parts leading to the truly zero waste production and the most energy saving. This paper reviews the technologies that help the formation of a circular metal additive manufacturing through recycling of the feedstocks and the damaged metal parts. Reactive metals, such as titanium, tend to be contaminated easily during handling and production. Recycling of the titanium for achieving a circular titanium additive manufacturing is reviewed in detail.
基金Project(52004342) supported by the National Natural Science Foundation of ChinaProject(150240015) supported by the Innovation-Driven Project of Central South University,ChinaProject(2021JJ20065) supported by the Natural Science Fund for Outstanding Young Scholar of Hunan Province,China。
文摘Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO_(2),V_(2)O_(5) and Al_(2)O_(3) in this study.The oxide mixture was first reduced by Mg in MgCl_(2) at 750℃ in argon,where oxygen was reduced to 2.47 wt%from 40.02 wt%.The oxygen content in the final powder was eventually reduced to an extremely low level(0.055 wt%)using calcium at 900℃ in argon,and the final powder had the composition of 90.12 wt%Ti,5.57 wt%Al,and 3.87 wt%V,which meets the standard specification of Ti-6Al-4V(ASTM F1108-09).Between the two reductions,a heat treatment step was designed to help controlling the specific surface area and particle size.The effect of the heat treatment temperature on the morphology,and composition uniformity of the powder was investigated in detail.Heat treatment above 1300℃ attributed to a dense powder with a controlled specific surface area.Thermodynamic modeling and experimental results indicated that onlyα-Ti enriched with Al andβ-Ti enriched with V exist in the final powder,and other possible phases including Al-Mg and Al-V were excluded.This study also offers a triple-step thermochemical process for producing high-purity Ti-based alloy powder.
基金financially supported by the National Natural Science Foundation of China(No.52004342)Innovation-driven Project of Central South University,China(No.502501015)the Natural Science Fund for Distinguished Young Scholar of Hunan Province,China(No.2019JJ20031)。
文摘A high-purity Ti-48Al-2Nb-2Cr alloy powder with an oxygen content as low as 0.0572 wt.%and a particle size of<150μm was produced from a mixture of TiO_(2),Al_(2)O_(3),Nb_(2)O_(5),and Cr_(2)O_(3)powders through reduction with magnesium and deoxidation with calcium.The phase and composition of the products were analyzed.The final product mainly includedγ-TiAl and minorα_(2)-Ti_(3)Al phases,and Ti,Al,Cr,and Nb were homogenously distributed in the powder with a mole ratio of 49.73:43.51:2.05:1.98.The reduction and deoxidation mechanisms were investigated by thermodynamic modeling using the HSC Chemistry software and Pandat software based on the Ti alloy database.
基金the National Natural Science Foundation of China(No.52004342)the Innovation-Driven Project of Central South University,China(No.150240015)the Natural Science Fund for Outstanding Young Scholar of Hunan Province,China(No.2021JJ20065).
文摘A direct production method of high-strength titanium alloy from upgraded titania slag(UGS)was developed.First,UGS was reduced into alloy powder with 1.3 wt.%oxygen using magnesium powder.Subsequently,the alloy powder was compacted at 600 MPa to produce a pellet.Lastly,the pellet was sintered to produce titanium alloy.The reduced powder was characterized,and the effect arising from the sintering temperature on the sintered density,compressive strength,microstructure,and hardness of the alloys was studied.The results showed that the density tended to increase with the temperature increasing from 900 to 1200℃,whereas the porosity decreased.A significant sintering densification was achieved at the temperature above 1100℃(98.65%at 1100℃ and 99.41%at 1200℃).At 1100℃,the hardness and compressive strength reached the maximal values of the alloy,HV 655.7 and 1563 MPa,respectively.
