Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of...Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of Si makes the reaction interface change from the lingual-tooth interface of hot-dip Al to the flat interface of hot-dip Al-Si.It also reduces the thickness of the alloy layer in the coating,especially the Fe_(2)Al_(5) layer.When the Si content is 1.5 wt%or 3.0 wt%,the diffusion channel crosses the conjugate line of the two-phase region(FeAl_(3)+liquid phase)into the FeAl_(3) single-phase region,and then moves to the region with higher Si content.Next,the diffusion channel cuts off the conjugate line of FeAl_(3)phase,τ_(1)/τ_(9) phase,and Fe_(2)Al_(5)phase,which promotes the form ofτ_(1)/τ_(9) phase.The formedτ_(1)/τ_(9) phase inhibits the diffusion between Fe and Al atoms.When the Si content is 7.0 wt%,the diffusion channel passes through the two-phase region(liquid phase+τ_(5))and enters theτ_(5) single-phase region.The form ofτ_(5) single-phase region has a strong inhibitory effect on the interatomic diffusion of Fe and Al,thereby reducing the thickness of the coating,especially the Fe_(2)Al_(5)layer.展开更多
Laboratory-scale experiments were performed to investigate the deoxidation of H13 tool steel with CaF_(2)-MgO-Al_(2)O_(3)-CaO-SiO_(2) slags at 1873 K.The calculation of thermodynamics and kinetics was also verified th...Laboratory-scale experiments were performed to investigate the deoxidation of H13 tool steel with CaF_(2)-MgO-Al_(2)O_(3)-CaO-SiO_(2) slags at 1873 K.The calculation of thermodynamics and kinetics was also verified through the experimental results.The results show that[Si]-[O]reaction is the control reaction,and with the increase of basicity of slag,the limitation of deoxidation was decreased.The limitation of deoxidation is the lowest for the slag with basicity of 2.0.Under the conditions of the basicity of 2.0 and the content of CaF_(2) more than 50%,the limitation of deoxidation is less than 10×10^(−6),and it does not depend on the contents of Al_(2)O_(3) and CaF_(2) in slags.The mass transport of oxygen in the metal phase is the rate-controlling step,and the slag composition has no effect on the equilibrium time of deoxidation.Based on this finding,the optimized slag composition is designed and it contains the following components:51.5%CaF_(2),20.3%MgO,16.2%Al_(2)O_(3),8.2%CaO and 3.8%SiO_(2).In the case of the optimized deoxidizing slag,the total oxygen content in H13 steel can be reduced from 25×10^(−6) to 6×10^(−6).展开更多
基金Projects(51971039,51671037)supported by the National Natural Science Foundation of ChinaProject(19KJA530001)supported by the Natural Science Research Project of Higher Education of Jiangsu,ChinaProject(KYCX21_2868)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘Based on the diffusion channel,the influence of Si content on the microstructure evolution of iron-based hot-dip Al-χSi coating was analyzed(χ=0,1.5 wt%,3.0 wt% and 7.0 wt%).The results show that the introduction of Si makes the reaction interface change from the lingual-tooth interface of hot-dip Al to the flat interface of hot-dip Al-Si.It also reduces the thickness of the alloy layer in the coating,especially the Fe_(2)Al_(5) layer.When the Si content is 1.5 wt%or 3.0 wt%,the diffusion channel crosses the conjugate line of the two-phase region(FeAl_(3)+liquid phase)into the FeAl_(3) single-phase region,and then moves to the region with higher Si content.Next,the diffusion channel cuts off the conjugate line of FeAl_(3)phase,τ_(1)/τ_(9) phase,and Fe_(2)Al_(5)phase,which promotes the form ofτ_(1)/τ_(9) phase.The formedτ_(1)/τ_(9) phase inhibits the diffusion between Fe and Al atoms.When the Si content is 7.0 wt%,the diffusion channel passes through the two-phase region(liquid phase+τ_(5))and enters theτ_(5) single-phase region.The form ofτ_(5) single-phase region has a strong inhibitory effect on the interatomic diffusion of Fe and Al,thereby reducing the thickness of the coating,especially the Fe_(2)Al_(5)layer.
基金Project(18SYXHZ0069)supported by the Science and Technology Program of Sichuan Province,ChinaProjects(51974139,51664021)supported by the National Natural Science Foundation of China。
文摘Laboratory-scale experiments were performed to investigate the deoxidation of H13 tool steel with CaF_(2)-MgO-Al_(2)O_(3)-CaO-SiO_(2) slags at 1873 K.The calculation of thermodynamics and kinetics was also verified through the experimental results.The results show that[Si]-[O]reaction is the control reaction,and with the increase of basicity of slag,the limitation of deoxidation was decreased.The limitation of deoxidation is the lowest for the slag with basicity of 2.0.Under the conditions of the basicity of 2.0 and the content of CaF_(2) more than 50%,the limitation of deoxidation is less than 10×10^(−6),and it does not depend on the contents of Al_(2)O_(3) and CaF_(2) in slags.The mass transport of oxygen in the metal phase is the rate-controlling step,and the slag composition has no effect on the equilibrium time of deoxidation.Based on this finding,the optimized slag composition is designed and it contains the following components:51.5%CaF_(2),20.3%MgO,16.2%Al_(2)O_(3),8.2%CaO and 3.8%SiO_(2).In the case of the optimized deoxidizing slag,the total oxygen content in H13 steel can be reduced from 25×10^(−6) to 6×10^(−6).
