Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the a...Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.展开更多
针对高强铝合金毛细芯结构的高精度成形及传质功能需求,研究了常规激光粉末床熔融(Conventional laser powder bed fusion,c-LPBF)与微细激光粉末床熔融(Micro laser powder bed fusion,μ-LPBF)成形高强铝合金微特征结构的成形性与毛...针对高强铝合金毛细芯结构的高精度成形及传质功能需求,研究了常规激光粉末床熔融(Conventional laser powder bed fusion,c-LPBF)与微细激光粉末床熔融(Micro laser powder bed fusion,μ-LPBF)成形高强铝合金微特征结构的成形性与毛细性能。μ-LPBF成形高强铝合金结构的极限尺寸约为86μm,缺陷等效直径集中于25~40μm,平均缺陷体积和球形度分别为9.99×10^(-6)mm^(3)、0.76;远优于c-LPBF工艺(缺陷等效直径50~100μm,球形度降至0.48),且在200μm以下结构展现出优异的尺寸精度与缺陷抑制能力。基于数值模型揭示了颗粒飞溅和剥蚀行为的演化机制,c-LPBF因强金属蒸汽羽流导致粉末飞溅速度超过10 m/s、剥蚀带宽度为821~932μm;而μ-LPBF因蒸汽扰动减弱,飞溅速度降至5 m/s以下、剥蚀带宽度缩小至159~239μm,工艺稳定性显著提升。μ-LPBF结构获得了更高的毛细压差-渗透率乘积(ΔP_(cap)K=16.08×10^(-8)N)与毛细因子(K/R_(eff)=1.16μm),展现出更均衡的综合传质性能,为热控结构的优化设计与一体化成形提供了参考。展开更多
基金the National Key Research and Development Program of China(2017YFB0304301)the Fundamental Research Funds for the Central Universities of Central South University(No.202044016).
文摘Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.
