2-2真空熔炼炉说课

12/19/20201真空应用Vacuum

Application主讲：王晓冬

xdwang@Vacuum

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真空冶金真空冶金的特点和分类√钢液真空处理√真空电炉的分类和组成真空感应熔炼真空电弧熔炼电子束熔炼2.3真空电炉分类和组成炉子—工业炉

区别其它如民用炉等，必有一个热源提供热量，热源

是炉子的核心部分。电炉—工业炉的一种以电能作为加热源。

工业炉还包括以煤炭、煤气、天然气、燃油等燃烧热为热源的燃烧炉。真空电炉—与普通电炉（大气下或保护气氛下）相比较，可以获得特殊的冶金效果。V1ac2u/u1m9/an2d02F0luid

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3University,

China真空电炉的分类根据电能向热能转变的方式可分为：真空电阻炉真空感应炉真空电弧炉电子束炉除炉体外电炉还包括一套电源、电控，以及真空系统。V1ac2u/u1m9/an2d02F0luid

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4University,

China真空电炉的组成炉体：真空室，实现工艺过程的条件和空间；电源、电控：为电炉提供能量，并按工艺要求实现控制；真空系统：获得并维持工艺需要的真空环境；水冷却系统。V1ac2u/u1m9/an2d02F0luid

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5University,

China加热体通电，因其电阻而发热，由对流、辐射、传导等方式传递给工件，使其被加热或融化。在真空条件下，传热以辐射为主。Q=I2R

→辐射给工件→T工件↑电源：交流、低压、大电流。由磁性调压变压器提供。Vacuum

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University,China1）真空电阻炉电阻炉的组成电阻炉的组成：炉体+电源、电控+真空系统炉体：

炉壳、保温炉衬、加热体、电极、观察窗、测温装置、测压装置、传动机构真空系统：泵+阀门+冷阱+管路+波纹管以油扩散泵或油增压泵系统为主。Vacuum

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University,China电源、电控+炉体+真空系统V1ac2u/u1m9/an2d02F0luid

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8University,

China炉体真空系统电控柜导电排Vacuum

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University,ChinaVacuum

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University,China电阻炉的分类按加热体位置分外热式和内热式按结构形式分立式和卧式按作业方式分周期式、半连续式、连续式按工作温度分低温炉、中温炉、高温炉Vacuum

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University,China外热式和内热式电阻炉Vacuum

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University,China周期式电阻炉Vacuum

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University,China半连续式电阻炉Vacuum

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University,China连续式电阻炉Vacuum

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University,China电阻炉的应用真空热处理真空钎焊

真空烧结

真空熔炼

真空除气

真空干燥等Vacuum

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University,China炉壳强度、稳定性、气密性；圆形、方形；炉盖—蝶形、椭圆形封头，或平底、平盖；材料：加热室采用不锈钢或碳钢内表镀镍、喷铝、涂覆有机材料。双层水套、冷却水管；内径尺寸400-4000mm已系列化。Vacuum

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University,China保温炉衬保温、节能；形状有圆形和方形；金属反射屏：钨、钽、钼、不锈钢厚壁式炉衬：石墨毡厚壁炉衬；陶瓷纤维毡厚壁炉衬；混合毡厚壁炉衬。Vacuum

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University,China加热体加热体提供炉子需要的热量（电阻热）；实现电能向热能的转化；是炉子的核心部分；决定炉子的工作能力（功率、温度）和寿命。金属加热体：纯金属—钨、钼、钽；金属合金加热体—镍铬合金、铁铬铝合金。非金属加热体：石墨、硅化钼、碳化硅。Vacuum

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University,China加热器加热器—用绝缘材料（陶瓷）零件将加热体与保温炉衬紧固成具有一定形状和较高高温强度的部件。加热器的尺寸：与料筐间距为50-150mm，长度为料筐的1.2—2倍。加热体与保温炉衬的间距：50-100mmVacuum

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University,China电极电极的作用导电—将低压大电流输入加热体；

绝缘—由玻璃层压板、聚四氟乙烯实现与炉体的绝缘；密封—由真空橡胶实现与炉体的静密封；

水冷—由水带走电极的发热量，保证其正常工作。材料：紫铜—导电好，导热好。结构：固定电极、可调电极。Vacuum

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University,China观察窗观测窗的作用观测炉内工作情况光学测温材料石英玻璃、耐火玻璃、钢化玻璃结构单层、双层玻璃观察窗Vacuum

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University,China温度测量测温装置：热电偶测温测点设置：多点测温，三点、六点、九点测温。Vacuum

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University,China电阻炉真空系统低真空系统中真空系统罗茨泵+机械泵油增压泵+机械泵高真空系统扩散泵+罗茨泵+机械泵扩散泵+机械泵扩散泵+油增压泵+机械泵Vacuum

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University,China2）真空感应炉交变电流流经感应线圈，使坩埚内的冶炼物料之中产生感生电流；电流流过物料产生的电阻热使其被加热、熔化；物料在真空中除气、精炼、合金化；最终在真空中完成浇铸，获得高质量的材料。Vacuum

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University,ChinaV1ac2u/u1m9/an2d02F0luid

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2U8niversity,

China电磁感应与涡流热电流产生磁场—电的磁效应

比奥-萨法尔定律：导体中通有电流时，导体周围空间和内部产生磁场。磁场满足叠加原理，方向遵守右手定则。交变磁场产生感生电场—交变磁场的电效应

法拉第电磁感应定律：当通过回路所包围的面积的磁通量发生变化时，回路上产生感生电动势，其大小与磁通量变化率成正比。集肤效应导体通有交流电时，导体内电流密度重新分布，外大内小—即为集肤效应。集肤效应的强弱与电流频率密切相关；频率越高，集肤效应越明显；同时，导体直径越大，集肤效应越明显。集肤效应使得导体有效导电面积减少，电阻增大。Vacuum

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University,China邻近效应当通有交流电的两个导体相互靠近时，由于相互作用，其中的电流重新分布。电流同向时，导体外侧电流密度>内侧；电流反向时，导体内侧电流密度>外侧。Vacuum

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University,China圆环效应通以交流电的线圈，其内部电流重新分布，并且内侧电流密度大于外侧的电流密度。只有导体直径d足够大，而圆环直径D较小时，圆环效应才会明显表现出来。Vacuum

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University,China综合效应感应器—圆环效应，电流集中在圆环内侧；熔材—集肤效应，电流集中在熔材的外侧；感应器与熔材—邻近效应，电流方向相反，使电流集中在两者靠近的一侧。综合效应—电流集中在感应器内侧和熔材的外侧。Vacuum

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University,China感应熔炼的综合效应Vacuum

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University,China电动力效应带电导体在磁场中受力（电动力）遵守左手定则，力的大小为：式中：P2—炉料吸收的功率；

f—电流频率；K—系数。Vacuum

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University,China电搅拌原理Vacuum

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University,China真空感应炉结构V1ac2u/u1m9/an2d02F0luid

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3U6niversity,

China炉子结构与组成炉体

外壳、合金加料箱、观察、取样装置、测温装置、坩埚、感应器、铸锭系统、翻转机构真空系统泵、阀门、阱、管路、检测仪表电源电控系统变频电源、电控柜、汇流排冷却系统泵、阀门、管路、检测仪表Vacuum

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University,ChinaV1ac2u/u1m9/an2d02F0luid

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3U9niversity,

China感应炉的分类按结构分：

1）卧式炉中、大型炉子，便于检修和操作立式炉中小型炉子,熔炼量<=25公斤炉体倾动式坩埚与炉体无相对运动下铸式(底漏式)坩埚和炉体都静止感应炉的分类（2）Vacuum

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University,China感应炉的分类（3）Vacuum

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University,China感应炉的分类（4）Vacuum

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University,China感应熔炼的特点整体保持液态便于加入合金元素,合金化方便便于搅拌,使温度均匀,物化反应充分自搅拌合金收得率高，烧损少功率调节方便通过并联电容,改变功率因数,调节功率熔炼成本偏高Vacuum

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University,China真空感应炉的主要结构炉体有足够的强度和刚度气密性选用非磁性材料坩埚材料小的线膨胀系数较高的机械强度材料良好的化学稳定性良好的电绝缘性材料放气量小Vacuum

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University,China真空感应炉的结构—感应器感应器：感应炉的核心部件，承担电能输入和能量转换任务，建立强的交变磁场，实现浇铸。满足电工要求—一定的安匝数满足机械要求满足水冷要求满足绝缘要求空心紫铜管绕制，中间通冷却水Vacuum

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University,China感应炉真空系统以油扩散泵为主泵的高真空系统；以油增压泵为主泵的中真空系统。Vacuum

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University,China冷坩埚半悬浮熔炼V1ac2u/u1m9/an2d02F0luid

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4U7niversity,

China电磁全悬浮熔炼Vacuum

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University,China3)真空电弧炉在真空中利用电弧放电产生的热量来加热和熔炼金属。金属电极在直流电弧高温作用下，迅速熔化并在水冷结晶器内进行再凝固。液态金属以熔滴的形式通过5000k的电弧区向结晶器滴落，使金属得到精炼；达到净化金属、改善结晶结构，提高材料性能的目的。电极为负极，熔池为阳极。Vacuum

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University,China电弧熔炼的特点优点熔炼不受耐火材料、大气和铸模的污染；可以生产大尺寸、大吨位金属锭；

快速定向结晶，可消除缩孔、偏析和中心疏松。缺点电极制造困难；锭子为柱状晶，沿径向变化，晶粒较大。Vacuum

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University,China真空电弧炉的分类自耗电炉：

电极由被熔材料制成,在熔炼过程中逐渐消耗,熔化后滴进结晶器中冷凝成锭。非自耗电炉：

电极由钨等高熔点材料制成,在炉料熔炼过程中基本不消耗。

非自耗炉有电极污染、电弧稳定性差、熔炼速度慢、合金成分比例难于控制。Vacuum

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University,China电弧炉的组成炉壳电极杆及传动装置（电机、减速器）观察装置坩埚及水冷系统真空系统、水冷系统液压系统（炉体的升降和转动）气动系统（阀门、电极卡头）电源设备、控制系统设备庞大，机械化、自动化程度高Vacuum

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University,China炉体转动型自耗炉Vacuum

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University,China直流电机用于正常熔炼交流电机用于快速提升和装卸电极Vacuum

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University,China坩埚及其水冷坩埚作用结晶器、热交换器、放电电极要求导热、导电性好，材料—紫铜、无氧铜、钢足够的刚度和强度整体式—适用于小炉，翻倒脱锭活底式—便于清除水锈和水垢脱锭式—熔池始终处于坩埚口处，污染少Vacuum

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University,China坩埚结构形式Vacuum

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University,China防暴装置Vacuum

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University,China观察装置Vacuum

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University,China观察装置Vacuum

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University,China真空系统Vacuum

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University,China真空电弧凝壳炉坩埚内部用被熔材料凝固成一层薄壳,成半球形；可以精炼金属合金,并浇铸异型铸件。Vacuum

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University,China凝壳炉结构组成Vacuum

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University,China凝壳炉坩埚结构Vacuum

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University,China4)电子束炉电子束炉是利用高速运动的电子具有的能量，轰击材料表面，并进行能量交换，使材料被加热和熔化的一种电炉。主要用于高温、难熔、高纯、稀有金属的熔炼（如铌、钽、铪等），获得高质量的材料。Vacuum

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University,China电子束流与材料的相互作用Vacuum

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University,China电子束炉的特点和应用特点(a)无耐火材料做坩埚，熔材无污染；(b)功率密度高：105W/cm2熔池温度高，可熔炼任何难熔金属(c)精炼效果好，可获得高纯材料：炉内真空度高滴熔—表面积大，放气充分温度高—除气、除杂质充分(d)功率调节方便：通过调节加速电压，调节加热功率；Vacuum

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University,China(e)合金成分控制不便；(f)设备复杂：□高压电源，多真空系统，操作维护要求高(g)产生X射线，需要防护。（2）应用

高温、难熔金属的熔炼：铌、钽、铪、钨、钼等；合金材料熔炼；钻孔、焊接、烧结。Vacuum

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