Oxidation of an aluminum-0.4 wt% magnesium alloy
Oxidation of an aluminum-0.4 wt% magnesium alloy
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氧化%20of%20an%20铝-0.4%20wt%%20镁%20合金
DOI：
10.1007/bf00275297
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
J. S. Kim
中科院分区：
文献类型：
--
作者：
Dong;E. Yoon;J. S. Kim
由于铝合金具有优异的耐腐蚀性能和良好的耐光强度，当今工业对铝合金的需求逐渐增加。随着废铝、废铝片、废饮料罐等铝副产品的不断增加，为了经济效益和环境保护，铝工业要求进行回收利用。然而，由于高温快速氧化的特点，在回收过程中会形成渣滓，导致大量铝金属的损失是不可避免的结果。在回收过程中，必须在中等温度（-300℃）下对铝屑和碎屑进行预处理，以去除工程油混合物和其他杂质，如加工过程产生的铁粉。回收工艺的目的是通过降低操作温度使氧化率降到最低，通过提高操作温度使表面残油混合物和其他金属杂质的去除效率达到最大。因此，本研究的目的是了解固态氧化，以便通过实验确定铝废料回收预处理的适宜操作环境。研究表明，一般情况下，含镁铝合金的氧化机理与纯铝不同。在熔点以下，高纯铝的氧化反应最初表现为近似线性的反应速率，随后反应速率随着重量的增加而迅速下降。然而，铝镁合金的氧化速率不符合任何常见的氧化规律，而是在200 - 400℃之间几乎呈抛物线状，在400℃以上几乎呈线性。在任何情况下，与高纯铝相比，A1-Mg合金的氧化速度要快得多，重量增加也大。在较低的温度下，氧化主要是由于A1或氧离子的热扩散，形成连续的无定形氧化膜，起到扩散屏障的作用，阻碍进一步的反应。当温度高于400℃时，7-A1203在金属-氧化物界面处成核，破坏连续的非晶态氧化膜[2]。如果合金中含有镁，则镁会通过形成MgA1204的纺锤状结构域来破坏连续的氧化膜，从而允许氧和金属离子通过开放途径快速交换。在
The industrial demands of aluminum alloys have been gradually increased today due to their useful properties, such as excellent corrosion resistance and proper strength with lighmess. Following the increasing amount of byproducts, such as Al-scrap, chip and used beverage cans, the aluminum industry demanded a recycling process for economic benefit and environmental conservation. However, significant Al-metal loss during the recycling process is an unavoidable consequence due to the formation of dross as a characteristic of rapid oxidation at high temperature. In the recycling process pretreatment at moderate temperatures (-300 C) of aluminum scraps and chips has to be performed to remove engineering oil-mixtures and other impurities, such as Fe-powder resulting from machining processes. The objective of the recycling process is to minimize the oxidation rate by lowering the operating temperamre and maximize the removal efficiency of the residual oil-mixture and other metal impurities on the surface by raising the operating temperature. Therefore the purpose of the present study is to understand the solid state oxidation in order to determine experimentally the appropriate operating environment for pretreatment of aluminum scrap recycling.It has been shown that, generally, aluminum alloy containing Mg has a different oxidation mechanism from that of pure aluminum. Oxidation of highpurity aluminum below the melting temperature is initially characterized by a near-linear reaction rate, followed by a rate which decreases rapidly with further weight gain. However, the oxidation rate of an aluminum-magnesium alloy does not conform to any common oxidation law, but is nearly parabolic at temperatures between 200 and 400 C, and nearly linear at temperatures above 400 C [1]. In any case, the oxidation rate of the A1-Mg alloy is much faster with large weight gain than that of high-purity aluminum. At a relatively low temperature, oxidation is mainly due to thermal diffusion of A1 or oxygen ions and causes a continuous amorphous oxide film that acts as a diffusion barrier retarding further reaction. At temperatures above 400 C, 7-A1203 nucleates at the metal-oxide interface to break the continuous amorphous oxide film [2]. If the alloy contains magnesium, magnesium facilitates disruption of the continuous oxide film by forming spindlike domains of MgA1204 that allow rapid exchange of oxygen and metal ions through open pathways. In