熔体抽拉金属纤维形成过程及缺陷形成分析  

Forming Process and Defects Formation of Metallic Fibers by Melt Extracted Method

作　　者：张树玲[1,2] 陈炜晔 耿桂宏 于永川[1] ZHANG Shuling;CHEN Weiye;GENG Guihong;YU Yongchuan(School of Mechanical Engineering,Ningxia University,Yinchuan 750021,China;School of Mechanical&Automotive Engineering,Qingdao University of Technology,Qingdao 266520,China;School of Materials Science and Engineering,North Minzu University of Nationalities,Yinchuan 750021,China)

机构地区：[1]宁夏大学机械工程学院,宁夏银川750021 [2]青岛理工大学,机械与汽车工程学院,山东青岛266520 [3]北方民族大学材料科学与工程学院,宁夏银川750021

出　　处：《宁夏工程技术》2020年第2期114-119,共6页Ningxia Engineering Technology

基　　金：国家自然科学基金资助项目(51604159)。

摘　　要：为解决制备金属纤维时存在的直径不均匀、竹节状缺陷等问题,采用数值模拟软件(ANSYS和FLUNET)对熔体抽拉金属纤维成形过程进行研究,并对纤维成形过程中熔融金属的运动及相场、温度场、流场的演变进行分析。结果表明,熔体表面稳定性和大的温度梯度容易导致纤维直径不均匀,特别是熔体与辊轮接触区。熔体的稳定性是决定金属纤维表面质量的重要因素,液面越不稳定,越容易出现带化及直径不均匀现象;纤维成形过程中熔体与辊面接触区域间存在具有一定角度的缝隙,随着纤维的成形并被甩出过程的持续,这一角度逐渐减小;而且该过程中熔体内部由于气相场的变化逐渐在不同区域产生涡流,发生卷气现象,凝固后由于气泡的塌陷,导致纤维凝固组织不均匀,形成表面凹凸等。对温度场演变的分析表明,不同区域冷却速率的差异使熔体内形成大的温度梯度,这导致熔池明显分层,靠近辊轮表面为流速最慢的过冷层,下方为流速最快的抽拉层,流体速度差使得金属纤维成形时容易在下游形成直径波动,这进一步加剧了金属纤维直径的波动。实验和理论分析表明,避免液面剧烈波动和大的温度梯度的产生是金属纤维成形的关键,表面光滑、直径均匀的金属纤维的成形需要金属熔体和熔体抽拉工艺的紧密配合。The metallic fiber forming process by melt extracted method is analyzed by numerical simulation software ANSYS and FLUNET.The characteristics of the melting pool are investigated before and after the molten metal is risen to the surface of the copper wheel.The phase field,temperature field,flow field and the formation mechanism of surface and microstructure defects during metal fiber forming process are analyzed.It is found that the uneven diameter is related to the surface instability of the molten alloy and temperature gradient.There is a gap with a certain angle between the upstream meniscus and the roll surface,which gradually decreases as the fiber is formed and extracted out.In this process,the gas-filling phenomenon induces bubbles in the solidified microstructure for the existence of local vortexes.The large temperature gradient causes the stratification of the molten pool,and near the roller is a supercooled layer characterized by the slowest flow rate and there is also a lower drawing layer with the fastest flow rate,which also leads to the diameter fluctuation of the metallic fibers.Therefore,the control of the molten pool is the key to get fine metallic fibers with smooth surface and uniform diameter.

关 键 词：熔体抽拉法 成形过程 相场 温度场 数值模拟 

分 类 号：TG146[一般工业技术—材料科学与工程]