应用电磁技术控制非晶带材制备工艺过程的基础研究

In planar flow casting (PFC) process for the manufacture of new functional material---amorphous ribbon, the effective controlling on the fluid flow, heat transfer and rapid solidification of the amorphous melt in PFC process is a key to the success of manufacturing the amorphous ribbon. In the present project, the idea of applying the exteriorly imposed electromagnetic field and utilizing its inducted forcing and/or heating effect to control the melt behaviors in PFC process is proposed. In combination with water model experiment of nozzle ladle (including the nozzle slip) and sample testing & analysis, a mathematical model of electromagnetic braking to describe the melt flow, heat transfer, surface level fluctuation and inclusion floatation in the nozzle ladle is developed and a model to describe the melt flow, heat transfer and solidification behavior in the melt puddle under the electromagnetic field is established. Based on the developed models, the interaction among the electromagnetic, the melt flow, heat transfer and/or solidification and their effects on the formation of amorphous ribbon under the imposed electromagnetic field are systematically investigated. The effects of the electromagnetic braking and electromagnetic pressurizing field on the melt behavior and the formation of amorphous ribbon are analyzed. By varying the typical process and operating parameters under the different induced electromagnetic intensities and electromagnetic field distributions, the melt behavior and the uniformity of the amorphous ribbon is studied and the key parameters to determine the operating widow formed by electromagnetic force, injection pressure, viscous force and surface tension force in PFC process is examined. The purpose of this project is to get an insight into the coupled physical phenomena of the melt behaviors under the action of the induced electromagnetic fields in PFC process and to provide a theoretical foundation on applying the electromagnetic field into the PFC process. It is expected that the present results can lead to form a new electromagnetic technology to control the melt behaviors in PFC process for amorphous ribbon.

在平面流铸法制备新型功能材料非晶带材工艺中，对非晶熔体的流动、传热和快速凝固行为实施有效控制是其成功关键。本项目提出引入外加的电磁场并利用其力效应/热效应来控制非晶熔体行为的研究思路。结合喷嘴包水模型实验和取样测试分析，通过建立描述电磁制动作用下喷嘴包（含喷嘴缝）熔体流动、传热、液面波动及夹杂物上浮的数学模型，以及建立电磁场作用下熔潭内流动、传热和快速凝固的数学模型，系统地研究引入的电磁场与熔体流动、传热或快速凝固等多物理现象之间的作用机理及其对非晶制带过程的影响。研究不同磁场强度和磁场分布下，典型工艺和操作参数(如嘴缝宽度、辊速等)改变对熔潭行为和非晶带材均匀性的影响，分析由电磁力、喷射压力、粘性力和表面张力所决定的工艺窗口关键参数。揭示电磁制动及电磁压力场对熔体行为及其非晶带形成的影响规律，为平面流铸法制备非晶带材工艺实施电磁控制提供理论基础，以期形成面向平面流铸法新的电磁场控制技术。

在平面流铸法制备新型功能材料非晶带材工艺中，对非晶熔体的流动、传热和快速凝固行为实施有效控制是其成功关键。本项目提出引入非接触外加电磁场，并利用其力效应/热效应来控制非晶熔体行为的研究思路。通过现场测试、水模型实验和数值模拟相结合方法，系统地研究了引入的电磁场与熔体流动、微细夹杂物、传热或快速凝固等多物理现象之间的作用机理其对非晶制带过程的影响。主要研究内容归类如下：(1)非晶喷嘴包浇注期实验测试及非晶薄带制备全流程的夹杂物分析；(2)非晶喷嘴包的控流装置水模拟及电磁制动作用下的喷嘴包结构设计优化；(3)喷嘴缝内的熔体流动行为及电磁场作用下熔潭布流行为分析；(4)电磁场对熔潭形状、快速凝固行为及其非晶带材形成影响的数值模拟；(5)平面流铸法制备非晶合金工艺的中试电磁装置设计。.项目组人员在执行期内完成了预期研究目标，取得了如下研究成果：.（1）获得了传统非晶制带工艺在长时间浇注期内温度、成份波动及带材质量均匀性的变化规律，首次揭示了非晶带材全流程工艺中夹杂物形成及来源机理。为满足大规模稳定且连续化的非晶宽带生产,水模型分析了一体式与传统分体式喷嘴包（含喷嘴缝）的流体流动行为，设计了改进型一体式喷嘴包结构及其与电磁制动相结合的控流方法。.（2）建立了电磁场作用下平面流铸法中喷嘴包流体流动及夹杂物去除的数学模型、电磁制动作用下喷嘴缝内的流动及传热行为、以及引入的电磁场和喷嘴缝附近直流载流线圈产生的磁场作用下的全域熔潭内三维流动、传热及快速凝固的数学模型。开发了外加电磁场应用于熔体流动、传热及凝固模拟的计算模型，分析了磁场模式、磁感应强度和磁场分布在典型工艺参数改变时对非晶熔体流动行为及其带材质量的影响，形成了利用外加电磁场控制平面流铸工艺过程的计算方法,为平面流铸法制备非晶带材工艺中开发新兴的电磁控制技术提供了理论基础。.（3）提出的平面流铸法中应用电磁制动控制喷嘴包流动行为、全域熔潭区域内的电磁场施加模式得到现场认可，设计了非晶制带工艺中试永磁体电磁装置。具有较好的实际应用价值。