12/19/20201真空應用Vacuum

Application主講：王曉冬

xdwang@Vacuum

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Fluid

Engineering

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University,China12/19/2020

22

真空冶金真空冶金的特點和分類√鋼液真空處理√真空電爐的分類和組成真空感應熔煉真空電弧熔煉電子束熔煉2.3真空電爐分類和組成爐子—工業(yè)爐

區(qū)別其它如民用爐等，必有一個熱源提供熱量，熱源

是爐子的核心部分。電爐—工業(yè)爐的一種以電能作為加熱源。

工業(yè)爐還包括以煤炭、煤氣、天然氣、燃油等燃燒熱為熱源的燃燒爐。真空電爐—與普通電爐（大氣下或保護氣氛下）相比較，可以獲得特殊的冶金效果。V1ac2u/u1m9/an2d02F0luid

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3University,

China真空電爐的分類根據(jù)電能向熱能轉變的方式可分為：真空電阻爐真空感應爐真空電弧爐電子束爐除爐體外電爐還包括一套電源、電控，以及真空系統(tǒng)。V1ac2u/u1m9/an2d02F0luid

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4University,

China真空電爐的組成爐體：真空室，實現(xiàn)工藝過程的條件和空間；電源、電控：為電爐提供能量，并按工藝要求實現(xiàn)控制；真空系統(tǒng)：獲得并維持工藝需要的真空環(huán)境；水冷卻系統(tǒng)。V1ac2u/u1m9/an2d02F0luid

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5University,

China加熱體通電，因其電阻而發(fā)熱，由對流、輻射、傳導等方式傳遞給工件，使其被加熱或融化。在真空條件下，傳熱以輻射為主。Q=I2R

→輻射給工件→T工件↑電源：交流、低壓、大電流。由磁性調壓變壓器提供。Vacuum

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University,China1）真空電阻爐電阻爐的組成電阻爐的組成：爐體+電源、電控+真空系統(tǒng)爐體：

爐殼、保溫爐襯、加熱體、電極、觀察窗、測溫裝置、測壓裝置、傳動機構真空系統(tǒng)：泵+閥門+冷阱+管路+波紋管以油擴散泵或油增壓泵系統(tǒng)為主。Vacuum

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University,China電源、電控+爐體+真空系統(tǒng)V1ac2u/u1m9/an2d02F0luid

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8University,

China爐體真空系統(tǒng)電控柜導電排Vacuum

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University,ChinaVacuum

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University,China電阻爐的分類按加熱體位置分外熱式和內熱式按結構形式分立式和臥式按作業(yè)方式分周期式、半連續(xù)式、連續(xù)式按工作溫度分低溫爐、中溫爐、高溫爐Vacuum

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University,China外熱式和內熱式電阻爐Vacuum

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Fluid

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University,China周期式電阻爐Vacuum

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University,China半連續(xù)式電阻爐Vacuum

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University,China連續(xù)式電阻爐Vacuum

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University,China電阻爐的應用真空熱處理真空釬焊

真空燒結

真空熔煉

真空除氣

真空干燥等Vacuum

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Fluid

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University,China爐殼強度、穩(wěn)定性、氣密性；圓形、方形；爐蓋—蝶形、橢圓形封頭，或平底、平蓋；材料：加熱室采用不銹鋼或碳鋼內表鍍鎳、噴鋁、涂覆有機材料。雙層水套、冷卻水管；內徑尺寸400-4000mm已系列化。Vacuum

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University,China保溫爐襯保溫、節(jié)能；形狀有圓形和方形；金屬反射屏：鎢、鉭、鉬、不銹鋼厚壁式爐襯：石墨氈厚壁爐襯；陶瓷纖維氈厚壁爐襯；混合氈厚壁爐襯。Vacuum

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University,China加熱體加熱體提供爐子需要的熱量（電阻熱）；實現(xiàn)電能向熱能的轉化；是爐子的核心部分；決定爐子的工作能力（功率、溫度）和壽命。金屬加熱體：純金屬—鎢、鉬、鉭；金屬合金加熱體—鎳鉻合金、鐵鉻鋁合金。非金屬加熱體：石墨、硅化鉬、碳化硅。Vacuum

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University,China加熱器加熱器—用絕緣材料（陶瓷）零件將加熱體與保溫爐襯緊固成具有一定形狀和較高高溫強度的部件。加熱器的尺寸：與料筐間距為50-150mm，長度為料筐的1.2—2倍。加熱體與保溫爐襯的間距：50-100mmVacuum

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University,China電極電極的作用導電—將低壓大電流輸入加熱體；

絕緣—由玻璃層壓板、聚四氟乙烯實現(xiàn)與爐體的絕緣；密封—由真空橡膠實現(xiàn)與爐體的靜密封；

水冷—由水帶走電極的發(fā)熱量，保證其正常工作。材料：紫銅—導電好，導熱好。結構：固定電極、可調電極。Vacuum

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University,China觀察窗觀測窗的作用觀測爐內工作情況光學測溫材料石英玻璃、耐火玻璃、鋼化玻璃結構單層、雙層玻璃觀察窗Vacuum

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University,China溫度測量測溫裝置：熱電偶測溫測點設置：多點測溫，三點、六點、九點測溫。Vacuum

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University,China電阻爐真空系統(tǒng)低真空系統(tǒng)中真空系統(tǒng)羅茨泵+機械泵油增壓泵+機械泵高真空系統(tǒng)擴散泵+羅茨泵+機械泵擴散泵+機械泵擴散泵+油增壓泵+機械泵Vacuum

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University,ChinaVacuum

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University,ChinaVacuum

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University,China2）真空感應爐交變電流流經(jīng)感應線圈，使坩堝內的冶煉物料之中產(chǎn)生感生電流；電流流過物料產(chǎn)生的電阻熱使其被加熱、熔化；物料在真空中除氣、精煉、合金化；最終在真空中完成澆鑄，獲得高質量的材料。Vacuum

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University,ChinaV1ac2u/u1m9/an2d02F0luid

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2U8niversity,

China電磁感應與渦流熱電流產(chǎn)生磁場—電的磁效應

比奧-薩法爾定律：導體中通有電流時，導體周圍空間和內部產(chǎn)生磁場。磁場滿足疊加原理，方向遵守右手定則。交變磁場產(chǎn)生感生電場—交變磁場的電效應

法拉第電磁感應定律：當通過回路所包圍的面積的磁通量發(fā)生變化時，回路上產(chǎn)生感生電動勢，其大小與磁通量變化率成正比。集膚效應導體通有交流電時，導體內電流密度重新分布，外大內小—即為集膚效應。集膚效應的強弱與電流頻率密切相關；頻率越高，集膚效應越明顯；同時，導體直徑越大，集膚效應越明顯。集膚效應使得導體有效導電面積減少，電阻增大。Vacuum

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University,China鄰近效應當通有交流電的兩個導體相互靠近時，由于相互作用，其中的電流重新分布。電流同向時，導體外側電流密度>內側；電流反向時，導體內側電流密度>外側。Vacuum

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University,China圓環(huán)效應通以交流電的線圈，其內部電流重新分布，并且內側電流密度大于外側的電流密度。只有導體直徑d足夠大，而圓環(huán)直徑D較小時，圓環(huán)效應才會明顯表現(xiàn)出來。Vacuum

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University,China綜合效應感應器—圓環(huán)效應，電流集中在圓環(huán)內側；熔材—集膚效應，電流集中在熔材的外側；感應器與熔材—鄰近效應，電流方向相反，使電流集中在兩者靠近的一側。綜合效應—電流集中在感應器內側和熔材的外側。Vacuum

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University,China感應熔煉的綜合效應Vacuum

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University,China電動力效應帶電導體在磁場中受力（電動力）遵守左手定則，力的大小為：式中：P2—爐料吸收的功率；

f—電流頻率；K—系數(shù)。Vacuum

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University,China電攪拌原理Vacuum

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University,China真空感應爐結構V1ac2u/u1m9/an2d02F0luid

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3U6niversity,

China爐子結構與組成爐體

外殼、合金加料箱、觀察、取樣裝置、測溫裝置、坩堝、感應器、鑄錠系統(tǒng)、翻轉機構真空系統(tǒng)泵、閥門、阱、管路、檢測儀表電源電控系統(tǒng)變頻電源、電控柜、匯流排冷卻系統(tǒng)泵、閥門、管路、檢測儀表Vacuum

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University,ChinaVacuum

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University,ChinaV1ac2u/u1m9/an2d02F0luid

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3U9niversity,

China感應爐的分類按結構分：

1）臥式爐中、大型爐子，便于檢修和操作立式爐中小型爐子,熔煉量<=25公斤爐體傾動式坩堝與爐體無相對運動下鑄式(底漏式)坩堝和爐體都靜止感應爐的分類（2）Vacuum

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University,China感應爐的分類（3）Vacuum

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University,China感應爐的分類（4）Vacuum

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University,China感應熔煉的特點整體保持液態(tài)便于加入合金元素,合金化方便便于攪拌,使溫度均勻,物化反應充分自攪拌合金收得率高，燒損少功率調節(jié)方便通過并聯(lián)電容,改變功率因數(shù),調節(jié)功率熔煉成本偏高Vacuum

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University,China真空感應爐的主要結構爐體有足夠的強度和剛度氣密性選用非磁性材料坩堝材料小的線膨脹系數(shù)較高的機械強度材料良好的化學穩(wěn)定性良好的電絕緣性材料放氣量小Vacuum

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University,China真空感應爐的結構—感應器感應器：感應爐的核心部件，承擔電能輸入和能量轉換任務，建立強的交變磁場，實現(xiàn)澆鑄。滿足電工要求—一定的安匝數(shù)滿足機械要求滿足水冷要求滿足絕緣要求空心紫銅管繞制，中間通冷卻水Vacuum

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University,China感應爐真空系統(tǒng)以油擴散泵為主泵的高真空系統(tǒng)；以油增壓泵為主泵的中真空系統(tǒng)。Vacuum

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University,China冷坩堝半懸浮熔煉V1ac2u/u1m9/an2d02F0luid

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4U7niversity,

China電磁全懸浮熔煉Vacuum

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University,China3)真空電弧爐在真空中利用電弧放電產(chǎn)生的熱量來加熱和熔煉金屬。金屬電極在直流電弧高溫作用下，迅速熔化并在水冷結晶器內進行再凝固。液態(tài)金屬以熔滴的形式通過5000k的電弧區(qū)向結晶器滴落，使金屬得到精煉；達到凈化金屬、改善結晶結構，提高材料性能的目的。電極為負極，熔池為陽極。Vacuum

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University,China電弧熔煉的特點優(yōu)點熔煉不受耐火材料、大氣和鑄模的污染；可以生產(chǎn)大尺寸、大噸位金屬錠；

快速定向結晶，可消除縮孔、偏析和中心疏松。缺點電極制造困難；錠子為柱狀晶，沿徑向變化，晶粒較大。Vacuum

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University,China真空電弧爐的分類自耗電爐：

電極由被熔材料制成,在熔煉過程中逐漸消耗,熔化后滴進結晶器中冷凝成錠。非自耗電爐：

電極由鎢等高熔點材料制成,在爐料熔煉過程中基本不消耗。

非自耗爐有電極污染、電弧穩(wěn)定性差、熔煉速度慢、合金成分比例難于控制。Vacuum

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University,China電弧爐的組成爐殼電極桿及傳動裝置（電機、減速器）觀察裝置坩堝及水冷系統(tǒng)真空系統(tǒng)、水冷系統(tǒng)液壓系統(tǒng)（爐體的升降和轉動）氣動系統(tǒng)（閥門、電極卡頭）電源設備、控制系統(tǒng)設備龐大，機械化、自動化程度高Vacuum

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University,China爐體轉動型自耗爐Vacuum

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University,China直流電機用于正常熔煉交流電機用于快速提升和裝卸電極Vacuum

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University,China坩堝及其水冷坩堝作用結晶器、熱交換器、放電電極要求導熱、導電性好，材料—紫銅、無氧銅、鋼足夠的剛度和強度整體式—適用于小爐，翻倒脫錠活底式—便于清除水銹和水垢脫錠式—熔池始終處于坩堝口處，污染少Vacuum

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University,China坩堝結構形式Vacuum

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University,China防暴裝置Vacuum

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University,China觀察裝置Vacuum

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University,China觀察裝置Vacuum

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University,China真空系統(tǒng)Vacuum

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University,China真空電弧凝殼爐坩堝內部用被熔材料凝固成一層薄殼,成半球形；可以精煉金屬合金,并澆鑄異型鑄件。Vacuum

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University,China凝殼爐結構組成Vacuum

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University,ChinaVacuum

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University,China凝殼爐坩堝結構Vacuum

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University,China4)電子束爐電子束爐是利用高速運動的電子具有的能量，轟擊材料表面，并進行能量交換，使材料被加熱和熔化的一種電爐。主要用于高溫、難熔、高純、稀有金屬的熔煉（如鈮、鉭、鉿等），獲得高質量的材料。Vacuum

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University,China電子束流與材料的相互作用Vacuum

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University,China電子束爐的特點和應用特點(a)無耐火材料做坩堝，熔材無污染；(b)功率密度高：105W/cm2熔池溫度高，可熔煉任何難熔金屬(c)精煉效果好，可獲得高純材料：爐內真空度高滴熔—表面積大，放氣充分溫度高—除氣、除雜質充分(d)功率調節(jié)方便：通過調節(jié)加速電壓，調節(jié)加熱功率；Vacuum

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of

Northeastern

University,China(e)合金成分控制不便；(f)設備復雜：□高壓電源，多真空系統(tǒng)，操作維護要求高(g)產(chǎn)生X射線，需要防護。（2）應用

高溫、難熔金屬的熔煉：鈮、鉭、鉿、鎢、鉬等；合金材料熔煉；鉆孔、焊接、燒結。Vacuum

and

Fluid

Engineering

Rese