镁合金熔体杂质形态及净化方法研究（本科毕业论文设计）.doc

镁合金熔体杂质形态及净化方法研究



摘    要


　　本文在分析镁熔体熔炼过程中一系列熔炼特性和杂质离析机理的基础上，将镁合金熔体的精炼原理和精炼工艺进行了一定深度的归纳研究。

就氧化性说，在实际熔炼条件下，元素的氧化反应不仅与 有关，而且与反应物的活度和分压有关。改变反应物或生成物的活度与炉气中反应物的分压，可影响氧化反应进行的趋势、顺序及程度，甚至改变反应进行的方向。这是进行控制或调整氧化还原反应的理论依据。而弄清熔炼条件下氧化反应的机制、控制氧化反应的环节及影响氧化速度的诸因素(温度、浓度、氧化膜结构及性质等)，可有效针对具体情况，改善熔炼条件，控制氧化速度，减少组元的氧化烧损。

由分压差脱除原理，除氢可采用精炼剂吸附脱除、吹气精炼脱除，以及振荡脱除。

    对混入镁合金熔体中的杂质，特别归纳分析了金属杂质Fe、Ni，因为它们是影响镁合金熔体质量的主要破坏因素；又主要讨论了目前国内使用稀土元素进行净化的熔剂精炼法，也综合文献资料指出吹气精炼是今后能够得到进一步发展的净化方法。




关键词：镁合金，精炼，杂质离析


 


ABSTRACT


Based on the analysis of series of melting characteristics and mechanism on segregation impurities which are in the process of melting magnesium, the principle of refining and

refining technology of magnesium alloy melt are studied summed up with a certain

depth.

On the oxidation of that, in actual melting conditions, the elements of not only with the response, but with the reaction of the activity and the pressure on. Change the reaction of the product or activity with the gas furnace in the reaction of the pressure, can affect the trend of oxidation, and the degree of order, and even change the direction of reaction. This is the control or adjustment of the redox reaction theory. And understand melting under the conditions of the response mechanism to control oxidation of the link speed and impact of the factors (temperature, concentration, structure and nature of oxide film, etc.), to be effective against specific circumstances, improve the melting conditions, control of speed, Reduce the element of the burning.

Removal of pressure from the principle, with the exception of hydrogen can be refined removal of adsorption, inflatable refining removal, and removal of oscillation.

Among the impurities mixed in magnesium alloy melt, Fe and Ni are investigated in particular, because they are the main factor lowering the quality of magnesium alloy melt; As a current domestic method of the flux refining, also discuss the rare earth elements used to purify melt; Literatures point out that inflatable refining can be further in the future development of the purification method.




Key words: Magnesium Alloy Melt，Refining，Segregation Impurities

 


目   录


中文摘要 Ⅰ

ABSTRACT Ⅱ

绪论 1

1 镁熔体熔炼特性 2

  1.1 镁的氧化性 2

    1.1.1氧化热力学条件 2

1.1.2 氧化动力学分析 4

1.1.3 影响氧化烧损的因素 6

1.1.4 降低氧化烧损的方法 6

1.2 镁的吸气性 7

1.2.1 气体在金属中的存在形态及来源 7

1.2.2 吸氢动力学过程 8

1.2.3 气体的溶解度及影响因素 9

  1.3 镁的吸杂性 10

2 熔体精炼原理 12

  2.1除渣精炼原理 12

  2.2脱气精炼原理 13

2.2.1 分压差脱气的热力学 14

2.2.2 分压差脱气的动力学分析 16

2.2.3 其他脱气方法 17

3 熔体精炼工艺 18

  3.1 熔剂精炼法 18

3.1.1 对熔剂的要求及熔剂的组成 18

3.1.2 除去镁中杂质的机理 19

  3.2镁熔体的除Fe工艺 20

3.3吹气精炼法 23

3.3.1 吹气精炼介质 23

3.3.2 吹气形式 23

3.3.3 国外几种投入生产的吹气精炼方法 25

   3.4稀土精炼 26

3.4.1 稀土与Cl元素的作用 26

3.4.2稀土去气去杂作用 27

结论 28

参考文献 29