【作者】 杨淼；

【导师】 曹志强；

【作者基本信息】 大连理工大学 ， 材料加工工程， 2006， 硕士

【摘要】 电磁分离技术是九十年代中后期发展起来的一种新型的熔体分离技术,其基本原理是利用夹杂物与金属的导电性差异,使夹杂物在电磁场中受到金属液的挤压力而向边界移动,以最终实现夹杂物的分离。电磁分离技术是一种处理量大、分离能力强、适应范围广、无污染的新型分离技术。目前该技术除在铝液净化方面得到广泛应用外,正在应用于制备不同表层性能的梯度复合材料,以满足实际生产中对材料特殊性能的要求。 为了对制备颗粒增强Al基自生梯度复合材料进行探索,本文利用高频磁场尝试制备了Al—Si,Al—Mg₂Si颗粒增强复合材料,通过试验确定了一个较佳的试验参数,并应用摸索出的有效试验参数制各了管状复合材料。通过x射线衍射分析及扫描电镜面扫描,确定了Al—Mg₂Si合金的相组成。通过测量显微硬度,结合金相照片分析了Al-Si复合材料的形成规律、影响因素、组织性能。试验结果表明:利用高频磁场的分离机理可以制备初晶Si及初生Mg₂Si颗粒沿径向呈梯度分布的棒状及管状Al基复合材料。当加载的磁场为6kW,加载时间为30s时,棒状试样获得了很好的分离效果。磁场强度及作用时间及磁场的热效应是影响分离效果的主要因素。通过控制外加磁场的电磁力参数和时间,并运用冷却方法来控制高频磁场的热效应对合金的温度的影响,可实现复合材料中初晶Si、初生Mg₂Si相颗粒的体积分数在径向呈既定的梯度规律变化。Al-Si合金复合材料的管状分离试样在加载磁场3kW下作用30s,试样的上部及下部的分离效果都很好,硬度在径向上呈对称分布。更多还原

【Abstract】 The electromagnetic separating technology is a new kind of separating liquid alloy technology. The basic principle is based on the electric discrepancy between the inclusion and alloy, the inclusion moves to outside by the extrusion force of electromagnetic field, and then the alloy got purified. Electromagnetic separating technology is mass disposal, strong separating force, wide used and none pollution. At present, it is not only widely used in aluminum alloy liquid purification, but also applied in gradient composite preparation of different surface performance to satisfy the request of material’s special performance.In order to prepare the particle reinforced Al-matrix composite material, high frequency electromagnetic field is used to fabricate the Al—Si, Al—Mg₂Si particle reinforced composite material. Through it, series of available experiment parameters are ascertained and hollow column composite materials are thus fabricated. By the X -Ra diffract analyze and SEM analyze, the phase of Al—Mg₂Si alloy is ascertained. By the measurement of micro-hardness and the metallographic photo, the formation rule, the structure and performance of Al-Si gradient composite material is analyzed. The result indicates that it is possible to use high frequency electromagnetic field to prepare the solid stick and hollow column Al—Si and Al—Mg₂Si particle reinforced composite material, in which the primary Si and Mg₂Si present the gradient distribution along radius direction. When the electromagnetic power is 6kW, and acting time 3Os, the solid stick samples got very good separation effect. The electromagnetic intensity, the acting time and the heat effect are the main factors which influence the separating result. By controlling the electromagnetic intensity, acting time and cooling method to release the electromagnetic field’s heat effect, it can actualize primary Si and Mg₂Si presenting gradient distribution along radius direction in Al—Si and Al—Mg₂Si alloy. The hollow column sample of Al-Si composite material has good separating result under power 3kW, time 30s. Its top and bottom sections both have good separating result, and the micro-hardness is symmetrical along radius direction.更多还原