【作者】 郭庆涛；

【导师】 金俊泽； 李廷举；

【作者基本信息】 大连理工大学 ， 材料加工工程， 2005， 硕士

【摘要】 电磁净化作为一种新兴的净化技术,由于其具有的洁净、高效,以及夹杂物的去除与密度差关系不大等特点,近年来已成为研究的热点之一。外加高频交变磁场的电磁净化方法更因为具有施加方便等特点而成为电磁净化领域的主要研究对象。 本文从电磁场的基本原理出发,根据金属熔体内部电磁体积力的数学表达式,建立了电磁净化时间计算模型,依靠此模型可以计算用电磁力去除理想金属熔体中的不同尺寸的非金属夹杂物所需的时间,以及圆管中的净化效率等。 为了验证电磁力对铝合金中不同尺寸的非金属夹杂物的电磁净化效果,配制了含硅量为18%、12.6%和10%的三种铝硅合金,其中,18%的铝硅合金又分为加磷、不加磷两种情况。在不同的凝固条件下,分别生成了尺寸为100μm、30μm和10μm的硅块,进而进行电磁净化模拟试验研究。试验结果证明,初生硅块可以较好地模拟铝熔体中的非金属夹杂物,在磁感应强度达到0.03T时,直径为100μm左右的非金属夹杂物可以在10s内被去除,单个尺寸在10μm的非金属夹杂物也可以依靠电磁挤压力去除。 针对去除小尺寸非金属夹杂物是净化过程中的难点问题,本文采用定点加入5μm氧化铝颗粒的方法,分别进行了如下验证性试验: 1.0.7mm铁芯外用铝箔包裹氧化铝颗粒,定点加入铝熔体中,检验在电磁力作用下细小陶瓷管内金属熔体的流动; 2.2mm铁芯外用铝箔包裹氧化铝颗粒,定点加入铝熔体中,模拟空心圆管电磁净化试验; 3.铝熔体中弥散分布有氧化铝颗粒后,取出铁芯,检验在细管中电磁净化去除铝熔体中细小非金属夹杂物的可行性。 试验结果表明,在磁感应强度达到0.03T以上时,铝熔体中的流动严重影响小尺寸非金属夹杂物的去除,即使利用空心圆管进行电磁净化试验,当磁感应强度为0.06T,净化时间达到120s,直径在5μm的氧化铝颗粒也不能完全去除。更多还原

【Abstract】 Electromagnetic Purification (EMP), which is a new technique of purification, has become one of research focuses because of its non-pollution, high-efficiency and less effect of the different density between the melt and nonmetallic inclusions. So AC magnetic field purification, which is one of the electromagnetic purification, has also become one of the main study hots because of its convenient application.In this paper, electromagnetic body force has been deduced on the base of the Maxwell equations and the model of EMP which can calculate purification time and efficiency of different diameter inclusions in molten metal has also been set up.In order to accurately analyze the effect of high frequency electromagnetic field on the non-metallic inclusions, the EMP experiments have been done with the 100 μm 、 30 μm and 10 pm primary silicons which are used to simulate the nonmetallic inclusions and are produced by 18%(with phosphor and without phosphor)、 12.6% and 10% Al-Si alloys respectively. The results show that the primary silicons are more suitable to simulate the non-metallic inclusions in molten aluminium. When the magnetic induction intensity is 0.03T, the non-metallic inclusions with the diameter 100 μm can be eliminated in 10 seconds. And the single non-metallic inclusions with the diameter 10 μm can also be eliminated by electromagnetic repulsive force.The key problem in EMP is how to eliminate minor diameter non-metallic inclusions. So alumina particles with diameter 5 μm have been added into molten aluminum at certain position.The following experiments are done:1. In order to verify the flow in molten aluminum with Electromagnetic body force, alumina particles have been added into melt at certain position with 0.7mm diameter iron core which is wrapped by aluminum foil;2. In order to simulate EMP in hollow pipe, alumina particles have been added into melt with 2mm diameter iron which is wrapped by aluminum foil;3. With alumina particles in the melt, EMP has been performed without iron core in tubule. The results show that when the magnetic induction intensity is more than 0.03T, the flow in themolten aluminum will strongly affect on elimination of minor diameter non-metallic inclusions. And even if the experiment is done in hollow pipe and the purification time is 120 seconds, thealumina particles with diameter 5 μm cannot be completely eliminated when the magnetic induction intensity is 0.06T.更多还原