Na2O对连铸保护渣熔化性能的影响

实验研究了Na2O对连铸保护渣熔化性能的影响规律，测定了实验渣系的熔化温度、熔化速度和结晶温度．结果表明，在实验渣基本成分条件下，Na2O的质量分数为10％时，保护渣的熔化特性能够满足高速连铸要求．     

Li2O对连铸保护渣熔化性能的影响

实验研究了Li2O对连铸保护渣熔化性能的影响规律,测定了实验渣系的熔化温度、熔化速度和结晶温度.结果表明,在实验渣基本成分条件下,Li2O的质量分数为3%时,实验保护渣具有较好的熔化性能.     

应用6σ法控制超低碳钢连铸过程增碳

应用6σ法对影响连铸过程的增碳因素进行分析,使用单因子方差分析法考察了钢包砖衬、开浇渣种类、中间包涂料批次、中包渣批次、保护渣种类等因素对超低碳钢增碳量的影响.结果表明,钢包砖衬、开浇渣种类、保护渣种类是影响超低碳钢增碳的主要因素.根据研究结果,在生产中采取了使用无碳砖衬钢包、无碳开浇渣、低碳结晶器保护渣等措施,铸坯增碳量显著降低,超低碳钢连铸工序增碳量小于3×10-6.     

F,MgO对包钢高炉渣性能影响的实验研究

根据目前包钢高炉渣的成分采用二次回归方法配制合成渣,通过对合成渣的粘度、熔化性温度及熔化区间的测定,研究F和MgO对包钢高炉渣性能的影响程度,寻求适宜的高炉渣成分.实验结果表明,当炉渣中w(F)≤1%时,CaF2具有降低炉渣开始熔化温度,增加炉渣熔化区间,降低炉渣热焓,降低炉渣粘度和炉渣熔化性温度的作用.随着炉渣中MgO的质量分数的增加,炉渣的热稳定性提高,炉渣粘度降低,当w(MgO)=11.652%时,熔化性温度达到最高值.     

超低碳钢连铸保护渣的特点

为了使保护渣良好地完成5个方面的作用，最重要的就是使控制结晶器保护渣粉形成“三层结构”．为此，在渣粉中配加适当碳粉以控制熔化速度．如果渣子熔化速度控制得合适，在结晶器液面上会形成“液渣-烧结-粉渣”的合理结构，再加上钢液面波动小，钢渣界面波动较小，渣中的碳消耗殆尽，不会造成铸坯增碳．     

结晶器保护渣各渣层碳含量的研究

以实验研究为基础,分析研究不同因素对结晶器保护渣各层碳含量的影响,寻找降低超低碳钢连铸过程中增碳的有效途径和方法,为该钢种结晶器保护渣的设计提供理论依据.     

CaO-BaO-Al2O3-SiO2-MgO-CaF2精炼渣系熔化温度研究

利用正交试验的方法进行CaO-BaO-Al2O3-SiO2-MgO-CaF2精炼渣系熔化温度的研究,结果表明,BaO的质量分数在0～15％范围内精炼渣系的熔化温度随BaO含量升高而降低;CaO/Al2O3含量比值由1增加到2,精炼渣系熔化温度逐渐升高,而CaO/Al2O3含量比值由2增加到4,精炼渣系熔化温度又开始下降;SiO2的质量分数由8％～20％,精炼渣系熔化温度随SiO2含量升高而升高.     

C，SiC和BN纳米管熔化与拉伸特性的分子动力学研究

采用Tersoff势的分子动力学方法,研究了(5,5)型单壁C,SiC和BN纳米管的熔化与轴向拉伸特性,给出了不同温度下各纳米管的形态、原子径向分布、能量变化以及拉伸力-应变曲线;根据模拟结果,分析了它们熔化与拉伸性能的差异。研究表明,C,SiC和BN纳米管的熔点分别为6 300,4 300,4 500 K左右,C及BN管熔化后呈现为网状,而SiC管为疏松的团簇;C纳米管的稳定性与拉伸性能均优于SiC和BN纳米管。     

CaF2对高炉炉渣性能影响的研究

针对F的质量分数小于1%的高炉炉渣的物理性能进行研究.实验结果表明:当炉渣中F的质量分数≤1%时,CaF2具有降低炉渣开始熔化温度,增加炉渣熔化区间,降低炉渣热焓,降低炉渣粘度和炉渣熔化性温度的作用.     

碱度和Al2O3对中碳钢宽厚板连铸结晶器保护渣粘度和熔化温度的影响

分别研究了碱度为0.92,1.0,1.14,碱度为1.0时Al2O3的质量分数为4.3％,5.0％,6.1％时中碳钢宽厚板连铸结晶器保护渣粘度和熔化温度的变化.试验结果表明,随着保护渣的碱度由0.92升高到1.14,保护渣的粘度逐渐降低.碱度的不断增加保护渣的半球点温度迅速上升.本渣系中随着Al2O3的质量分数由4.3％增加到6.1％,保护渣粘度逐渐降低,保护渣粘度的降低保证了保护渣的润滑特性.Al2O3质量分数的增加对保护渣半球点温度的影响不是很剧烈,对保护渣的熔化温度起到降低的作用.     

中薄板坯连铸保护渣研究

系统地研究了中薄板坯连铸保护渣的化学成分与理化性能，熔化温度、熔化速度和粘度的关系，探讨了保护渣中的Al2O3、F^-、碳质量分数及碱度的大小对保护渣理化性能的影响，得到了优化的保护渣成分，为开发满足现场工艺要求的中薄板坯连铸保护渣提供理论依据和指导。     

冷轧超低碳钢带表面缺陷的研究与分析

针对马钢CSP工艺生产的某品种冷轧超低碳钢带表面缺陷进行了详细的统计和分析,同时对现场收集到的典型缺陷试样进行金相和扫描电镜分析,找出了钢带表面缺陷的种类、来源及分布的变化规律。对冷轧超低碳钢带表面缺陷分析发现缺陷主要是由具有结晶器保护渣特征的钙铝酸盐夹杂物、钙铝酸盐和硫化钙共生的夹杂物以及表面条状的氧化铁皮压入造成。本文根据表面缺陷分析研究的结果提出了相应的工艺控制措施,降低了表面缺陷的发生率。     

连铸结晶器保护渣熔点影响因素的研究

以生产现场实际使用的连铸结晶器保护渣为研究对象,研究碱度、碱金属氧化物含量、Al2O3含量和F含量对保护渣熔点的影响。结果表明,保护渣熔点随Al2O3含量和碱度增大呈先略微降低后逐渐升高势态,随碱金属氧化物和F含量的增加呈先显著降低后趋于平缓趋势。     

烧结与冷镦过程中铝硅共晶合金显微结构与密度的演变

采用烧结及后续的镦粗工艺制备了铝硅共晶合金块体材料,研究了烧结温度对烧结体显微结构、抗压强度及相对密度的影响。结果表明：烧结温度显著影响烧结体的显微结构和抗压强度,以临近铝硅共晶合金液相线的温度烧结时,发生了局部熔化,产生的熔融液体破坏了颗粒表面的氧化膜,颗粒之间相互黏结,形成了烧结骨架。以优化的555℃烧结,Si颗粒呈球状,抗压强度达到最佳,但相对密度未发生变化。在后续的冷镦过程中,烧结骨架及粉末颗粒均产生变形,孔隙减小,颗粒呈扁平状,相对密度达到了98%。     

Heating and melting mechanism of stainless steelmaking dust pellet in liquid slag

The heating and melting mechanisms of the pellets immersed in liquid slag were investigated, and the effect of the pellet heating and the melting conditions were studied. The results show that the dust component in the pellet is melted from the surface and no metallic elements are melted before the dust component, the time for the pellet completely melted is reduced as the iron powder content increases since the metallic iron has high thermal conductivity. These are four stages of heating and melting of pellet in liquid slag, they are the growth and melt of solid slag shell, penetration of liquid slag, dissolving of dust component and melting of reduced metals. The lifetime of the solid slag shell is in the range of 7-16 s and increasing the pre-heating temperature of the pellet and the slag temperature can shorten the slag shell lifetime. The time for the dust component in the pellet to be melted completely is in the range of 20-45 s and increasing the pre-heating temperature, especially in the range of 600-800 ℃, can obviously reduce the melting time. A higher slag temperature can also improve the pellet melting and the melting time is reduced by 10-15 s when the slag temperature is increased from 1 450 to 1 550 ℃. The pellet with higher content of iron powder is beneficial to the melting by improving the heat conductivity.     

Transition of Y<Subscript>2</Subscript>BaCuO<Subscript>5</Subscript> phase in powder melting processed YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−x</Subscript> superconductors

The morphology and the formation of Y2BaCuO5 phase in powder melting processed YBa2Cu3O7-x superconductors were investigated. The experimental results show the heat treatment can not change the shape of Y2BaCuO5 particles in powder melting processed samples. The formation of round Y2BaCuO5 phase is due to relative content of each constitution of precursor powders in powder melting process. For powder melting process, the excessive liquid phase is eliminated, which restrains the preferred growth of Y2BaCuO5 ...     

Experimental study on Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the ferrite region

A Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the conventional austenite region and in the ferrite region with lubrication was experimentally studied.Subsequent cold rolling and continuous annealing processes were also conducted.The results show that microstructures of ultra-low carbon bake hardening hot strips at room temperature are basically irregular polygonal ferrites.The yield strength,ultimate tensile strength,n value,and r value of the No.2 specimen hot-rolled in the ferr...     

The Influence of Mold Pressing Parameters on PTC of HDPE／CB Composites

The influence of mold pressing parameters on the positive temperature coefficrent of high-density polyethylene/carbon black composites was investigated. The composites with a low resistivity at room temperature and a high positive temperature coefficient can be obtainee with the mold pressing parameters as follows : mold pressing pressure 6- 14 MPa, mold pressing temperature 150- 170℃, mold pressing time about 15 min, and room temperature of molded specimen after cooling for 20- 60 minutes. The positive temperature coefficient effect of the composite is 7.7 when it is prepared under the mold pressing parameters , and the negative temperature coeffcient effect is less than 0. 8. Scanning electron microscopy (SEM) reveals some aggregations of carbon black panicles with a size of 1μm inside the composite, which was obtained at the mold pressing temperature of 180℃.