锌合金成本控制.doc

锌合金成分控制1. 标准合金成分Zamak 2Zamak 3Zamak 5ZA8SuperloyAcuZinc 5铝3.8 4.33.8 4.33.8 4.38.2 8.86.6 7.22.8 3.3铜2.7 3.30.0300.7 1.10.9 1.33.2 3.85.0 6.0镁0.035 0.06 0.035 0.060.035 0.060.02 0.0350.0050.025 0.05铁0.0200.0200.0200.0350.0200.075铅0.0030.0030.0030.0050.0030.005镉0.0030.0030.0030.0050.0030.004锡0.0010.0010.0010.0010.001 0.08%时，产生热脆、韧性下降、流动性下降。 易在合金熔融状态下氧化损耗。 镁对合金流动性的影响。（4）杂质元素：铅、镉、锡 使锌合金的晶间腐蚀变成十分敏感，在温、湿环境中加速了本身的晶间腐蚀，降低机械性能，并引起铸件尺寸变化。 当锌合金中杂质元素铅、镉含量过高，工件刚压铸成型时，表面质量一切正常，但在室温下存放一段时间后（八周至几个月），表面出现鼓泡。（5）杂质元素：铁 铁与铝发生反应形成Al5Fe2金属间化合物，造成铝元素的损耗并形成浮渣。 在压铸件中形成硬质点，影响后加工和抛光。 增加合金的脆性。 铁元素在锌液中的溶解度是随温度增加而增加，每一次炉内锌液温度变化都将导致铁元素过饱和（当温度下降时），或不饱和（当温度上升时）。当铁元素过饱和时，处于过饱和的铁将与合金中铝发生反应，结果是造成浮渣量增加。当铁元素不饱和时，合金对锌锅和鹅颈材料的腐蚀将会增强，以回到饱和状态。两种温度变化的一个共同结果是最终造成对铝元素的消耗，形成更多的浮渣。 1.the function of every element in metal The valid elements in metal : aluminum, copper, magnesium; the baneful impure elements: lead, cadmium, tin, iron(1) aluminum function: to improve the metals capability in casting, improve its liquidity, fine crystal, cause strengthening solid-liquid, improve mechanical capability to reduce the reacting capability of zinc to iron, reduce eroding to the iron material ,such as goose , mold, pot.Content of aluminum should be controlled in the scope of 3.8%-4.3% which is thiought mainly about the asked intensity and liquidity. Liquidity is the requirement to obtain a whole cast with precise dimention and smooth surface.Attached is the drawing 3 of the influence of aluminum to liquidity and mechanical capability. The highest liquidity is at the point when the content of aluminum is 5%; when the content of aluminum is reduced to 3%, the liquidity is the lowest. The influence of aluminum to intensity is drawn as a broken line in drawing 3. The highest intensity is at the point when the content of aluminum is 3.5%; when the content of aluminum is improved to 6%, the liquidity is the lowest. When the content of aluminum is over 4.3%, metal will be crisp. When the content of aluminum is under some asked scope, it will be difficult to make cast with thin wall.It is possible to be broken when the cast be cold. The bad influence of aluminum in metal is to produce Fe2A13 scruff which will cause the content of aluminum reducing.(2) copper function: to improve metals rigidity and intensity; to improve metal capability of resisting friction; to reduce eroding among crystaldisadvantage: If the content of copper is over 1.25%, casts dimension and mechanical intensity will be changed as time goes by. to reduce metal extensibilityfunction: to improve attached is the drawing 4 of the influence of content of copper to metal intensity.(3) magnesium function: to reduce eroding among crystal to fine structure of metal to improve metal intensity; to improve metal capability of resisting fictiondisadvantage: when the content of magnesium is over 0.08%, metal will be hot and crisp, its tenacity and liquidity will be reduced ;be easy to be oxidation and wasted when metal is melting.Influence of magnesium to metal liquidityThey will make eroding in crystal of zinc metal very sensitive , which will accelerate its eroding in crystal in warm and wet environment , reduce mechanical capability, and cause change of cast dimension.If the content of impure elements such as lead, cadmium in zinc metal is more high, quality of cast surface will be normal when the workpiece is cast. After a time in room temperature (8 weeks to some months), the surface will heave vesicles. (5) impure element: iron Metal compound Al5Fe2 formed by the reaction between iron and aluminum will cause aluminum to be wasted and produce scruff. to form horniness in cast to influence after-processing and polishing to increase metal brittleness The more temperature is increased, the more solubility of iron in zinc liquid is increased. Change of temperature of zinc liquid in furnace will cause iron over-saturated (when temperature is fallen)or unsaturated (when temperature is increased). If iron is over-saturated, redundant iron will react with aluminum in metal and cause scruff increased.