200930479 九、發明說明 【發明所屬之技術領域】 本文所述之具體實施例槪括關於用於離心鑄造高反應 性金屬的方法。更特別地，本文之具體實施例槪括敘述用 於離心鑄造高反應性鈦合金且特別爲鋁化鈦合金的方法。 【先前技術】 〇 渦輪引擎設計者連續不斷地找尋具有減少引擎重量及 獲得較高的引擎操作溫度之改進特性的新材料。鈦合金（ Ti合金）及特別爲以鋁化鈦爲主之合金（TiAl合金）具 有低溫機械特性，諸如室溫延展性及韌性，以及中高溫強 度與蠕變抗性的有前途組合。就這些理由而言，TiAl合金 具有代替目前用於製造許多渦輪引擎鑄件的以鎳爲主之超 合金之潛力。 真空電弧再熔融法（VAR)爲一種常用於熔融Ti合 © 金的技術。VAR通常包含在放入水冷卻之銅坩堝爐中的鈦 合金電極與相同的合金片（例如，電極末端）之間擊出電 弧。建立熔融池且電極漸漸熔融。當足夠的熔融金屬可取 得時，則可將電極撤除及將坩堝爐傾斜，將金屬倒入用於 鑄造鑄件的模具中。 VAR技術可具有許多缺點。在VAR法中所使用的鈦 電極可能昂貴，因爲高成本的鈦坯料/煅料及從檢定之廢 料及返回材料生產電極所涉入之高勞動成本。而且，對預 合金電極的要求可使其有困難且以高價產製不標準的合金 -4- 200930479 。此外，對使用水冷卻之坩堝爐的需求可限制在金屬中可 達成之過熱程度，其進而可影響流動性’導致塡充薄壁鑄 件時的困難度。而且，最高的溫度存在於電弧擊中金屬之 處且高溫梯度存在於熔融金屬中。這亦可影響模具的塡充 及在固化鑄件時建立差的溫度梯度。 有鑑於上述以VAR技術的爭議，在熔融Ti合金時可 使用的另一方法爲真空感應熔融（VIM)。發展VIM以用 〇 於加工不可能在空氣中熔融及鑄造的含有反應性元素（諸 如鈦及鋁）之專有且奇特合金。當該等合金的使用繼續增 加時，則V IM因此變得更司空見慣。 真空感應熔融通常包含在從非感應性耐火合金氧化物 所製成之坩堝爐中加熱金屬，直到在坩堝爐內的金屬進料 熔融成液體形式。在該技術中，將固體鈦合金片放入經常 由銅所製成的冷卻之金屬爐床中及在惰性氣體中使用非常 強的熱源，諸如電弧或電漿熔融。熔融池最初形成在鈦進 G 料的內部及頂端表面上，但是鄰接於銅爐床的密封壁之鈦 保持爲固體。該發展之固體鈦的$凝殼〃含有沒污染的液 體鈦金屬。參見頒予Rowe之美國專利第4,654,858號關 於冷壁感應熔融的槪括討論。 如先前所論及，銅坩堝爐就許多理由而言最常用在高 反應性合金的冷壁感應熔融中。例如，從陶瓷坩堝爐熔融 及鑄造可在坩堝爐上引入顯著的熱應力，其可造成坩堝爐 裂開。該裂開可減少坩堝爐壽命及導致在鑄造之鑄件中有 雜質。而且’高反應性TiAl合金可使陶瓷坩堝爐破裂及 200930479 以來自氧化物的氧及耐火合金二者污染鈦合金。同樣地， 如果使用石墨坩堝爐，則鋁化鈦可從坩堝爐溶解大量的碳 至鈦合金中，因而造成污染。該污染可造成鈦合金的機械 特性損失。 銅較不可能展現先前所述與陶瓷及石墨坩堝爐有關聯 的問題，這是爲什麼在使用冷壁感應熔融時，典型地使用 銅坩堝爐來熔融高反應性金屬合金。 〇 然而，雖然在銅坩堝爐中的冷坩堝爐熔融可給予先前 所述之高反應性合金加工的冶金術優勢，但是其亦有許多 技術及經濟限制，包括低過熱、由於凝殼形成的產率損失 及高動力需求。特別地，在坩堝爐的動力停止及允許金屬 陷落至模具的水冷卻之銅面時，則冷壁感應坩堝爐遭受熱 損失。 已用於先前所述以真空感應熔融之爭議的一項發展爲 經由噴嘴從冷的爐床熔融系統的床底傾倒。參見頒予 〇 Rowe之美國專利第4,546,858號及頒予Wang等人之美國 專利第5,1 64,097號。典型地被使用之噴嘴材料爲銅或黃 銅’其被認爲是好的熱傳導材料。亦曾述及以石墨及隔熱 材料用作噴嘴材料。 雖然噴嘴的使用可提供許多超越其他常見操作的好處 ’但是噴嘴的使用不完全免除複雜化的可能性。例如，反 應性金屬（諸如鈦）的冷爐床熔融及床底傾倒可在噴嘴中 造成不希望的熔融凝固。另外，許多坩堝爐/噴嘴系統可 致力提供必要的液體流速控制、減至最低的噴嘴侵蝕及減 -6 - 200930479 至最低的熔融污染。 已用於先前所述以真空感應熔融之爭議的另一項發展 爲懸浮熔融，其通常包含使用來自感應線圈的能量以電磁 懸浮熔融金屬。參見頒予 Fishman等人之美國專利第 5，27 5,229號關於懸浮熔融的槪括討論。然而，雖然磁感 應場可同時加熱金屬及保持熔融金屬懸浮在坩堝爐內的空 間中，但是一旦系統的動力源關閉時，則金屬可滑落回到 〇 水冷卻之坩堝爐中且在其傾倒之前再度驟冷。這可造成不 完全的模具塡充。 因此，雖然有前述發展，但是仍對熔融高反應性金屬 合金（諸如TiAl )之改進方法有需要，其允許合金在傾倒 期間維持熔融，還減少與習知的熔融法有關聯的爭議出現 【發明內容】 〇 本文的具體實施例槪括關於用於離心鑄造高反應性鈦 金屬的方法，其包含提供具有數個感應線圈及可移除之底 板的冷壁感應坩堝爐，使用動力源加熱在感應坩堝爐中的 鈦金屬進料，以獲得熔融金屬，預加熱第二坩堝爐及放置 預加熱之第二坩堝爐至離心鑄造機中，具有第二坩堝爐的 離心鑄造機放置在感應坩堝爐之下，撤除感應坩堝爐的底 板及關閉至感應坩堝爐的動力源，以允許熔融金屬從感應 坩堝爐落入第二坩堝爐中，及加速第二坩堝爐，以離心迫 使熔融金屬至鑲造模具中，以製造鑄件。 200930479 本文的具體實施例亦槪括關於用於離心鑄造高反應性 鈦金屬的方法，其包含提供具有數個感應線圈及可移除之 底板的冷壁感應坩堝爐，使用動力源加熱在感應坩堝爐中 的鈦金屬進料，以獲得熔融金屬’預加熱第二坩堝爐及放 置預加熱之第二坩堝爐至離心鑄造機中’放置漏斗在感應 坩堝爐之下，放置具有第二坩堝爐的離心鑄造機在漏斗之 下，撤除感應坩堝爐的底板及關閉至感應坩堝爐的動力源 Ο ，以允許熔融金屬從感應坩堝爐經由漏斗落下且落入第二 坩堝爐中，及加速第二坩堝爐，以離心迫使熔融金屬至鑄 造模具中，以製造鑄件。 具體實施例亦槪括關於用於離心鑄造高反應性鋁化鈦 的方法，其包含提供具有數個感應線圈及可滑動移除之底 板的冷壁感應坩堝爐，使用動力源加熱在感應坩堝爐中的 鋁化鈦進料，以獲得熔融鋁化鈦，預加熱第二坩堝爐及放 置預加熱之第二坩堝爐至離心鑄造機中，放置鈮漏斗在感 ® 應坩堝爐之下，放置具有第二坩堝爐的離心鑄造機在鈮漏 斗之下，滑動移除感應坩堝爐的底板及關閉至感應坩堝爐 的動力源，以允許熔融鋁化鈦從感應坩堝爐經由鈮漏斗落 下且落入第二坩堝爐中，在熔融鋁化鈦落入第二坩堝爐之 後，使第二坩堝爐維持從約0.5至約2秒之靜態，及使第 二坩堝爐在從約1秒至約2秒之內加速至從約1 00 rpm至 約600 rpm，隨後以離心迫使熔融鋁化鈦至鑄造模具中， 以製造低壓渦輪葉片鑄件。 從下列的揭示內容使得這些及其他特點、觀點及優勢 - 8 - 200930479 爲那些熟習本技藝者所明白。 【實施方式】 本文所述之具體實施例槪括關於離心鑄造高反應性金 屬的方法，且特別爲鈦合金及鋁化鈦合金，經由隨後但不 應被限制於此的所敘述之該方法鑄造成最終形狀（net shape )鑄件。 Q 依照下文的敘述’可提供如圖1中所示之具有爐體12 的冷壁感應坩堝爐10°爐體12可從任何具有好的熱及電 傳導性的金屬製成’諸如銅。爐體12可以水冷卻’以避 免在坩堝爐加熱期間銅之熔融。更特別地’銅通常在約 1 900T (約 l〇38°C )下熔融及 TiAl 在約 2600°F (約 1427 °C )下熔融，且在坩堝爐中的銅可形成具有鈦的低共熔物 。以水冷卻坩堝爐可避免此出現。可使用水冷卻入口 24 及出口 26循環經由數個放置在爐體12周圍之通道28的 φ 冷卻水。雖然爐體12可具有任何所欲且可接受用於感應 熔融的形狀，但是在一個具體實施例中，通常可將爐體12 定型成空心圓筒。爐體12可具有數個放置於其周圍的感 應線圈14，其可使用動力源21加熱。線圈14可用作爲熱 源，以熔融放入坩堝爐內的金屬進料及維持其熔融態，如 下文所述。 坩堝爐10亦可具有可移除之底板16，如圖1所示。 與坩堝爐10 —樣，底板16可包含任何具有好的熱及電傳 導性的金屬，且在一個具體實施例中，其可包含銅。底板 -9- 200930479 16亦可以水冷卻及具有數個放置在其下的感應線圈14 ’ 再幫助放入的金屬進料以坩堝爐10熔融及維持其溶融態 。另外，電絕緣板19可圈限底板16，有助於維持在坩堝 爐10底部的熱。如下文所討論，底板16可以各種方式從 爐體12移除，包括但不限於滑動（如圖2及3中所示） 、旋轉、降落及類似方式。 在使用時，可將包含高反應性合金的金屬進料18放 ❹ 入堪堝爐的爐體12內部’如圖1中所不。在一個具體 實施例中，金屬進料18可包含鈦合金’且更特別爲鋁化 鈦合金，並可呈任何可接受之形式，其可包括’但不限於 團粒、錠塊、顆粒、平板、粉末及其混合物。那些熟習本 技藝者將瞭解放入坩堝爐10中的金屬進料18量可依據意 欲用途而變動，然而’在一個具體實施例中’可使用從約 1磅（約454公克）至約3.5磅（約1588公克）’而在另 一具體實施例中’可使用從約丨.25磅（約567公克）至 © 約3.3磅（約149 7公克）金屬進料18製備成最終形狀之 低壓渦輪葉片，如下文所述。 一旦將金屬進料18放入坩渦爐10內部時’可將在一 個具體實施例中可從與堪禍爐10相同的材料所製成之蓋 子20放置在爐體12頂端上及使蓋環22固定在適當之處 ，以確保坩堝爐1〇密封。可將動力源21開啓及金屬進料 18可在達成適當的溫度時熔融’在一個具體實施例中’該 溫度可從約2700下至約2835°F (約1480°C至約1557°C) 。那些熟習本技藝者將瞭解由感應線圈所產生的電磁場引 -10 - 200930479 起金屬進料本身內部加熱，其係由於在金屬進 所引起的電阻加熱。當金屬進料1 8開始熔融 熔融金屬30可變成懸浮在坩堝爐10的爐體 只要將動力施予坩堝爐1〇則熔融金屬30不劈 部接觸。該熔融金屬30懸浮液可避免形成凝憲 與金屬進料在坩堝爐10中熔融的同時， 堝爐3 2或其他類似的固定裝置使用任何可接 〇 加熱，諸如但不限於微波或輻射能量。第二坩 墨或陶瓷製成，並可選擇地具有金屬襯墊，諸 坩堝爐32可協助熔融金屬轉移至鑄造模具中 任何在感應坩堝爐1〇中的感應熔融期間所產 屬中的過熱。更特別地，當第二坩堝爐32包 可將第二坩堝爐32預加熱至至少約1 832°F () ，而在一個具體實施例中，從約1832 °F至斧 1000 °C至約1200 °C)，且當第二坩堝爐包含陶 © 加熱至至少約1 9 8 0 °F (約1 0 82 °C )，而在一 例中，從約1 9 8 0 °F至約2 4 0 0 T ( 1 0 8 2 °C至約 預加熱可有助於避免熱衝擊及第二坩堝爐32 許其再使用。接著將預加熱的第二坩堝爐32 造機36的旋轉臂34中及放置在感應坩堝爐] 圖3中的槪括展示。任何習知的離心鑄造機可 使用，諸如 Linn High-Therm Titancast 700 SEIT Supercast (義大利）。 接著可將可移除之底板16從坩堝爐10¾ 料內的電流 時，則所得 12內，使得 I爐體12內 卜 可將第二坩 受之方式預 堝爐可從石 如鈮。第二 ，而不損失 生之溶融金 含鈮時，則 約 1 00 0〇C ) 3 2 2 0 0 °F ( 瓷時，則預 個具體實施 13 16。。）° 裂開，可允 放入離心鑄 I 0之下，如 接受於本文 (德國）或 ί爐體12撤 -11 - 200930479 除，如先前所述。在圖2及3中所示之具體實施例中， 將底板1 6使用任何可接受之機件（諸如但不限於軌道 導軌）從坩堝爐10以滑動移除，雖然底板16被移除， 是由感應線圈14所產生的電磁場可維持熔融金屬30在 堝爐10的爐體12內處於懸浮狀態，如圖2中所示，直 進一步加工爲止。 當動力源2 1關閉時，則允許熔融金屬30從感應坩 © 爐1〇經由鈮漏斗33落下且落入預熱的第二坩堝爐32 ，使其在鑄造機36內可維持長至剛好足以使熔融金屬 完成其轉移至第二坩堝爐32中的靜態，在一個具體實 例中，其可爲從約0.5至約2秒。一旦熔融金屬30的 移完成時’可將第二坩堝爐32迅速（約1至約2秒） 速至全速’其可從約100 rpm至約600 rpm。鑄造機36 以離心迫使熔融金屬30離開第二坩堝爐32及經由通口 進入鑄造模具38中，該通口可包含狹縫、洞、管或其 ¥ 合中之至少一者。從第二坩堝爐32至鑄造模具38中的 快速轉移造成在少於約5秒的2秒之間的接觸時間。該 暫的接觸時間不僅顯著地減少熱損失，並亦有助於確保 熔融金屬與建構第二坩堝爐32所使用的石墨或陶瓷之 沒有任何不希望的反應。 鑄造模具38可包含任何陶瓷包模鑄造系統，其提 惰性表面塗層及隔熱背襯材料。在一個具體實施例中， 爲實例之鑄造模具38可包含表面塗層，其包括氧化物 如本文所使用的"氧化物〃係指選自氧化銃、氧化釔、 可 或 但 坩 到 堝 中 30 施 轉 加 可 40 組 該 短 在 間 供 作 〇 氧 -12- 200930479 化給、氧化鑭系金屬及其組合物的組成物。此外，氧化鑭 系金屬（亦稱爲、稀土金屬〃組成物）可包含選自氧化鑭 、氧化鈽、氧化鐯、氧化銳、氧化鉅、氧化衫、氧化銪、 氧化纟L、氧化Μ、氧化鏑、氧化鈥、氧化鉬·、氧化鏡、氧 化鍇及其組合物的氧化物。鑄造模具38可包含背襯，其 包括在膠態二氧化矽懸浮液中選自氧化鋁、矽酸銷、二氧 化砂及其組合物的附火材料。 〇 一旦將熔融金屬實質地轉移至鑄造模具38中時，可 將離心鑄造機36關閉。所得鑄件可使用習知的慣例從鑄 造模具38取出’在一個具體實施例中，該鑄件可爲低壓 渦輪葉片42，如圖4中所示。因爲使用離心鑄造，所以葉 片42需要些微的鑄造後加工。由鑄造機36所產生的離心 力係藉由改進模具的薄片塡充而提供最優化之鑄造模具38 塡充，藉此提供最終形狀鑄件。 而且’因爲冷壁坩堝爐被用於熔融金屬進料，所以在 〇 坩堝爐上有較少的熱應力，而因此較少的坩堝爐裂開。這 可同時允許坩堝爐再使用及在鑄件中有較少的雜質。另外 ，因爲在熔融金屬與第二坩堝爐之間的接觸時間有限，所 有熔融金屬有來自坩堝爐破裂之污染的可能性減低。較少 的污染可造成改進的鈦合金之機械特性。 本書面說明書使用實例揭示本發明，包括最佳模式， 並亦能夠使任何熟習本技藝者達成及使用本發明。本發明 的專利範圍係以申請專利範圍定義，並可包括由那些熟習 本技藝者發現的其他實例。如果該等其他實例具有與申請 -13- 200930479 專利範圍之字面語言沒有差異的結構元件時，或如果該等 包括具有與申請專利範圍之字面語言無實質差異的同等結 構元件時，則意欲使該等實例在申請專利範圍內。 【圖式簡單說明】 圖1爲依據本文所述之具有金屬進料放入其中的冷壁 感應坩堝爐的一個具體實施例之橫截面示意圖； Ο 圖2爲依據本文所述之具有移除之底板及熔融金屬懸 浮於其中的冷壁感應坩堝爐的一個具體實施例之橫截面示 ttV. rgt · 息圖* 圖3爲依據本文所述之離心鑄造系統的一個具體實施 例之橫截面示意圖；及 圖4爲可依據本文所述而鑄造之一個具體實施例的低 壓渦輪葉片鑄件之立體示意圖。 Ο 【主要元件符號說明】 1〇:冷壁感應坩堝爐 12 :爐體 1 4 :線圈 16 :可移除之底板 1 8 :金屬進料 1 9 :電絕緣板 20 :蓋子 2 1 :動力源 -14- 200930479 :蓋環 ❹ :水冷卻入口 :水冷卻出口 •通;il :熔融金屬 :第二坩堝爐 =漏斗 :旋轉臂 :鑄造機 :鑄造模具 :通口 :低壓渦輪葉片 -15-200930479 IX. Description of the Invention [Technical Fields of the Invention] Specific embodiments described herein include methods for centrifugally casting highly reactive metals. More particularly, specific embodiments herein describe methods for centrifugally casting highly reactive titanium alloys, particularly titanium aluminide alloys. [Prior Art] 涡轮 Turbine engine designers are constantly looking for new materials with improved features that reduce engine weight and achieve higher engine operating temperatures. Titanium alloys (Ti alloys) and alloys based on titanium aluminide (TiAl alloys) have low-temperature mechanical properties such as room temperature ductility and toughness, as well as promising combinations of medium and high temperature strength and creep resistance. For these reasons, TiAl alloys have the potential to replace the nickel-based superalloys currently used to make many turbine engine castings. Vacuum arc remelting (VAR) is a technique commonly used to melt Ti composite © gold. VAR typically involves arcing between a titanium alloy electrode placed in a water cooled copper crucible and the same alloy piece (e.g., electrode tip). A molten pool is established and the electrodes gradually melt. When sufficient molten metal is available, the electrode can be removed and the crucible can be tilted to pour the metal into a mold for casting the casting. VAR technology can have a number of disadvantages. The titanium electrode used in the VAR process can be expensive because of the high cost of titanium billet/calcination and the high labor costs associated with the production of electrodes from certified waste and return materials. Moreover, the requirements for pre-alloyed electrodes make it difficult and cost-effective to produce non-standard alloys -4- 200930479. In addition, the need for a furnace that uses water cooling can limit the degree of superheat that can be achieved in the metal, which in turn can affect the flowability, which can result in difficulties in filling thin wall castings. Moreover, the highest temperature exists where the arc strikes the metal and a high temperature gradient exists in the molten metal. This can also affect the filling of the mold and establish a poor temperature gradient when curing the casting. In view of the above controversy over VAR technology, another method that can be used in melting Ti alloys is vacuum induction melting (VIM). VIM has been developed to process proprietary and exotic alloys containing reactive elements such as titanium and aluminum that cannot be melted and cast in air. As the use of these alloys continues to increase, V IM has therefore become more commonplace. Vacuum induction melting typically involves heating the metal in a crucible made from a non-inductive refractory alloy oxide until the metal feed in the crucible melts into a liquid form. In this technique, a solid titanium alloy sheet is placed in a cooled metal hearth often made of copper and a very strong heat source such as an electric arc or a plasma is used in an inert gas. The molten pool is initially formed on the inner and top surfaces of the titanium feed, but the titanium adjacent to the seal wall of the copper hearth remains solid. The development of the solid titanium $capsule contains uncontaminated liquid titanium metal. See U.S. Patent No. 4,654,858 to Rowe for a discussion of cold wall induction melting. As previously discussed, copper beryllium furnaces are most commonly used in cold wall induction melting of highly reactive alloys for a number of reasons. For example, melting and casting from a ceramic crucible can introduce significant thermal stresses on the crucible that can cause the crucible to crack. This cracking reduces the life of the crucible and causes impurities in the cast casting. Moreover, the 'highly reactive TiAl alloy can rupture the ceramic crucible and 200930479 contaminates the titanium alloy with both oxygen and refractory alloys from the oxide. Similarly, if a graphite crucible furnace is used, the titanium aluminide can dissolve a large amount of carbon from the crucible furnace into the titanium alloy, thereby causing contamination. This contamination can cause loss of mechanical properties of the titanium alloy. Copper is less likely to exhibit the problems previously associated with ceramic and graphite crucible furnaces, which is why copper crucible furnaces are typically used to melt highly reactive metal alloys when cold wall induction melting is used. However, although the cold head melting in a copper crucible furnace can give the metallurgical advantages of the previously described highly reactive alloy processing, it also has many technical and economic limitations, including low overheating and the formation of agglomerates. Loss of rate and high power demand. In particular, the cold wall induction crucible suffers from heat loss when the power of the crucible is stopped and the metal is allowed to sink to the water-cooled copper side of the mold. One development that has been used in the previously discussed controversy of vacuum induction melting is to pour from the bottom of a cold hearth melting system via a nozzle. See U.S. Patent No. 4,546,858 issued to 〇 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。. The nozzle material typically used is copper or brass 'which is considered a good heat conducting material. It has also been mentioned that graphite and thermal insulation materials are used as nozzle materials. Although the use of nozzles offers many advantages over other common operations', the use of nozzles does not completely eliminate the possibility of complications. For example, cold hearth melting of a reactive metal such as titanium and bed bottom dumping can cause undesirable melt solidification in the nozzle. In addition, many furnace/nozzle systems are dedicated to providing the necessary fluid flow control, minimizing nozzle erosion and reducing -6 - 200930479 to the lowest melt contamination. Another development that has been used in the previously discussed controversy of vacuum induction melting is suspension melting, which typically involves the use of energy from an induction coil to electromagnetically suspend molten metal. See U.S. Patent No. 5,27,229, the disclosure of which is incorporated herein by reference. However, although the magnetic induction field can simultaneously heat the metal and keep the molten metal suspended in the space inside the crucible, once the power source of the system is turned off, the metal can slide back into the hydrophobically cooled crucible and re-introduced before it is dumped. Quenching. This can result in incomplete mold filling. Thus, despite the foregoing developments, there is still a need for improved methods for melting highly reactive metal alloys, such as TiAl, which allow the alloy to remain molten during pouring, and also reduce the controversy associated with conventional melting processes. The specific embodiments herein include a method for centrifugally casting highly reactive titanium metal, comprising providing a cold wall induction crucible having a plurality of induction coils and a removable bottom plate, using a power source to heat the induction The titanium metal in the crucible is fed to obtain molten metal, the second crucible is preheated, and the preheated second crucible is placed in the centrifugal casting machine, and the centrifugal casting machine having the second crucible is placed in the induction crucible Next, removing the bottom plate of the induction crucible and the power source that is closed to the induction crucible to allow the molten metal to fall from the induction crucible into the second crucible furnace, and accelerate the second crucible to centrifugally force the molten metal to the inlay mold In order to manufacture castings. 200930479 Specific embodiments herein also include a method for centrifugally casting highly reactive titanium metal comprising providing a cold wall induction crucible having a plurality of induction coils and a removable backing plate, using a power source to heat the induction crucible The titanium metal in the furnace is fed to obtain a molten metal 'preheating the second crucible and placing the preheated second crucible into the centrifugal casting machine'. The placement funnel is placed under the induction crucible and placed with the second crucible. The centrifugal casting machine is under the funnel, removing the bottom plate of the induction crucible and the power source 关闭 closed to the induction crucible to allow the molten metal to fall from the induction crucible through the funnel and into the second crucible, and accelerate the second crucible In the furnace, the molten metal is forced into the casting mold by centrifugation to manufacture a casting. Specific embodiments also include a method for centrifugally casting highly reactive titanium aluminide comprising providing a cold wall induction crucible having a plurality of induction coils and a slidably removable bottom plate, using a power source to heat the induction furnace The titanium aluminide is fed to obtain molten titanium aluminide, preheating the second crucible furnace and placing the preheated second crucible furnace into the centrifugal casting machine, placing the crucible funnel under the induction furnace, and having The centrifugal furnace of the second crucible is under the crucible funnel, slidingly removes the bottom plate of the induction crucible and the power source that is turned off to the induction crucible to allow the molten titanium aluminide to fall from the induction crucible through the crucible funnel and fall into the first In the second crucible furnace, after the molten titanium aluminide falls into the second crucible furnace, the second crucible furnace is maintained static from about 0.5 to about 2 seconds, and the second crucible furnace is from about 1 second to about 2 seconds. The internal acceleration is from about 100 rpm to about 600 rpm, and then the molten aluminide titanium is forced into the casting mold by centrifugation to produce a low pressure turbine blade casting. These and other features, viewpoints, and advantages are made from the following disclosures - 8 - 200930479 for those skilled in the art. [Embodiment] The specific embodiments described herein include a method for centrifugally casting a highly reactive metal, and particularly a titanium alloy and a titanium aluminide alloy, cast by the method described later, but should not be limited thereto. Causes a net shape casting. Q According to the following description, a cold wall induction crucible having a furnace body 12 as shown in Fig. 1 can be provided. The furnace body 12 can be made of any metal having good heat and electrical conductivity such as copper. The furnace body 12 can be water cooled to avoid melting of the copper during heating of the crucible. More specifically, 'copper is usually melted at about 1 900 T (about 10 ° C ° C) and TiAl is melted at about 2600 ° F (about 1427 ° C), and the copper in the crucible can form a low total of titanium. Melt. This can be avoided by cooling the oven with water. The water cooling inlet 24 and the outlet 26 can be circulated through a plurality of φ cooling water placed in the passage 28 around the furnace body 12. While the furnace body 12 can have any desired shape and is acceptable for induction melting, in one embodiment, the furnace body 12 can generally be shaped into a hollow cylinder. The furnace body 12 can have a plurality of inductive coils 14 placed around it that can be heated using a power source 21. The coil 14 can be used as a heat source to melt the metal feed placed in the crucible and maintain its molten state, as described below. The crucible 10 can also have a removable bottom plate 16, as shown in FIG. As with the crucible 10, the bottom plate 16 can comprise any metal having good thermal and electrical conductivity, and in one embodiment, it can comprise copper. The bottom plate -9- 200930479 16 can also be water cooled and has a plurality of induction coils 14 ′ placed underneath to assist the metal feed to melt and maintain its molten state. In addition, the electrically insulating plate 19 can enclose the bottom plate 16 to help maintain heat at the bottom of the furnace 10. As discussed below, the bottom plate 16 can be removed from the furnace body 12 in a variety of ways including, but not limited to, sliding (as shown in Figures 2 and 3), rotation, landing, and the like. In use, the metal feed 18 comprising the highly reactive alloy can be placed inside the furnace body 12 of the crucible furnace' as shown in Figure 1. In a particular embodiment, the metal feed 18 can comprise a titanium alloy 'and more particularly a titanium aluminide alloy, and can be in any acceptable form, which can include, but is not limited to, pellets, ingots, granules, slabs, Powder and mixtures thereof. Those skilled in the art will appreciate that the amount of metal feed 18 placed in the crucible 10 can vary depending on the intended use, however 'in one particular embodiment' can be used from about 1 pound (about 454 grams) to about 3.5 pounds. (about 1588 grams) and in another embodiment 'a low pressure turbine can be prepared from a metal feed 18 of about 丨25 pounds (about 567 grams) to about 3.3 pounds (about 149 7 grams). Blades, as described below. Once the metal feed 18 is placed inside the vortex furnace 10, a cover 20 that can be made from the same material as the smashing furnace 10 can be placed on the top end of the furnace body 12 and the cover ring can be placed in a particular embodiment. 22 is fixed where appropriate to ensure that the crucible is sealed. The power source 21 can be turned on and the metal feed 18 can be melted when a suitable temperature is reached. 'In a particular embodiment, the temperature can range from about 2700 down to about 2835 °F (about 1480 ° C to about 1557 ° C). . Those skilled in the art will appreciate that the electromagnetic field generated by the induction coil induces internal heating of the metal feed itself, which is due to resistance heating caused by metal ingress. When the metal feed 18 starts to melt, the molten metal 30 can become suspended in the furnace body of the crucible furnace 10. As long as the power is applied to the crucible furnace, the molten metal 30 is not in contact with the crucible. The molten metal 30 suspension avoids the formation of a condensate and metal feed in the crucible 10 while the crucible 32 or other similar fixture uses any connectable heating such as, but not limited to, microwave or radiant energy. The second ink or ceramic is made of, and optionally has, a metal liner which assists in the transfer of molten metal to the superheat in the casting mold during induction melting during induction melting in the induction furnace. More particularly, the second crucible 32 can preheat the second crucible 32 to at least about 1 832 °F (), and in one embodiment, from about 1832 °F to the axe 1000 °C to about 1200 ° C), and when the second furnace contains pottery © heated to at least about 1890 ° F (about 10 82 ° C), and in one case, from about 1 890 ° F to about 2 4 0 0 T (1 0 8 2 ° C to about preheating can help avoid thermal shock and reuse of the second crucible 32. The preheated second crucible 32 is then placed in the rotating arm 34 of the machine 36 Placed in an induction cooker] The display in Figure 3. Any conventional centrifugal casting machine can be used, such as the Linn High-Therm Titancast 700 SEIT Supercast (Italy). The removable bottom plate 16 can then be removed from the oven. When the current in the material is 103⁄4, the result is 12, so that the first furnace 12 can pre-heat the furnace from the stone, and the second, without losing the raw molten gold. Then about 100 〇C) 3 2 2 0 0 °F (for porcelain, the first implementation is 13 16 ..) ° Split, can be placed under the centrifugal casting I 0, as accepted (Germany) or ί herein furnace 12 evacuate -11--200930479 addition, as previously described. In the particular embodiment illustrated in Figures 2 and 3, the bottom plate 16 is slidably removed from the crucible 10 using any acceptable mechanism, such as but not limited to a track rail, although the bottom plate 16 is removed, The electromagnetic field generated by the induction coil 14 maintains the molten metal 30 in a suspended state within the furnace body 12 of the crucible 10, as shown in Fig. 2, and is further processed. When the power source 21 is turned off, the molten metal 30 is allowed to fall from the induction furnace 1 through the crucible funnel 33 and into the preheated second crucible 32 so that it can be maintained in the casting machine 36 for just enough The molten metal is allowed to complete its transfer to the statics in the second crucible 32, which in one embodiment may range from about 0.5 to about 2 seconds. Once the transfer of molten metal 30 is complete, the second crucible 32 can be rapidly (about 1 to about 2 seconds) to full speed, which can range from about 100 rpm to about 600 rpm. The casting machine 36 centrifugally forces the molten metal 30 away from the second crucible 32 and into the casting mold 38 via the port, which may include at least one of a slit, a hole, a tube, or a combination thereof. The rapid transfer from the second crucible 32 to the casting mold 38 results in a contact time of less than about 2 seconds of 2 seconds. This temporary contact time not only significantly reduces heat loss, but also helps to ensure that the molten metal does not have any undesired reaction with the graphite or ceramic used to construct the second furnace 32. Casting mold 38 can comprise any ceramic overmold casting system that provides an inert surface coating and an insulating backing material. In a specific embodiment, the casting mold 38 of the example may comprise a surface coating comprising an oxide as used herein, "oxide lanthanide refers to cerium oxide, cerium oxide, or may be 30 The application of 40 groups of this short-term supply for the composition of yttrium oxide-12-200930479, lanthanide metal and its composition. In addition, the cerium oxide-based metal (also referred to as a rare earth metal cerium composition) may be selected from the group consisting of cerium oxide, cerium oxide, cerium oxide, oxidized sharp, oxidized giant, oxidized smear, cerium oxide, cerium oxide L, cerium oxide, and oxidized. Oxides of cerium, cerium oxide, molybdenum oxide, oxidizing mirrors, cerium oxide and combinations thereof. The casting mold 38 can comprise a backing comprising an igniting material selected from the group consisting of alumina, citric acid pins, silica sand, and combinations thereof in a colloidal ceria suspension.离心 Once the molten metal is substantially transferred into the casting mold 38, the centrifugal casting machine 36 can be closed. The resulting casting can be removed from the casting mold 38 using conventional conventions. In one embodiment, the casting can be a low pressure turbine blade 42, as shown in FIG. Because centrifugal casting is used, the blade 42 requires a slight post-casting process. The centrifugal force generated by the casting machine 36 provides an optimized casting mold 38 nip by improving the sheet sizing of the mold, thereby providing a final shape casting. Moreover, because the cold wall furnace is used for the molten metal feed, there is less thermal stress on the crucible furnace, and thus less furnace cracking. This allows the furnace to be reused and has less impurities in the casting. In addition, since the contact time between the molten metal and the second crucible is limited, the possibility that all of the molten metal has contamination from the collapse of the crucible is reduced. Less contamination can result in improved mechanical properties of the titanium alloy. The written description uses examples to disclose the invention, including the best mode, and the invention can The patentable scope of the invention is defined by the scope of the claims, and may include other examples found by those skilled in the art. If such other instances have structural elements that do not differ from the literal language of the scope of the patent application - 13-200930479, or if such include equivalent structural elements that are not substantially different from the literal language of the scope of the patent application, Examples are within the scope of the patent application. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross-sectional view of one embodiment of a cold wall induction crucible having a metal feed placed therein in accordance with the present invention; Ο Figure 2 is removed in accordance with the teachings herein. A cross-sectional view of a particular embodiment of a cold wall induction crucible in which a bottom plate and molten metal are suspended is shown in FIG. 3 is a cross-sectional schematic view of one embodiment of a centrifugal casting system in accordance with the present invention; 4 is a perspective view of a low pressure turbine blade casting of a specific embodiment that can be cast in accordance with the teachings herein. Ο [Main component symbol description] 1〇: Cold wall induction furnace 12: Furnace 1 4 : Coil 16 : Removable bottom plate 1 8 : Metal feed 1 9 : Electrical insulation plate 20 : Cover 2 1 : Power source -14- 200930479 : Cover ring ❹: Water cooling inlet: Water cooling outlet • Pass; il: Molten metal: Second furnace = Funnel: Rotating arm: Casting machine: Casting mold: Through port: Low pressure turbine blade-15-