.200940208 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 性金屬之系統。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鈦鋁化物合金之系 統。 U 【先前技術】 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）及特別爲以鈦鋁化物爲主之合金（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。 φ 真空電弧重熔法（VAR)爲一種常用於熔融Ti合金的技 術。VAR通常包含衝擊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）之間的電弧。 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成本勞動。而且，對預 -5- 200940208 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。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，其依次可影響流動性，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衝擊金屬 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用於加 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VIM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 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"凝殻〃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 -6- 200940208 雜質。而且，高反應性TiAl合金可使陶瓷坩堝爐破裂及 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，則鈦鋁化物可從-坦堝爐溶解大量的 碳至鈦合金中，藉此造成污染。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連 的問題，這是爲什麼在使用冷壁感應熔融時，典型地使用 φ 銅坩堝爐來熔融高反應性金屬合金。 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，但是其亦可具許 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 屬陷落以對抗模具的水冷卻之銅面時，則冷壁感應坩堝爐 遭受熱損失。 已用於提出先前所述以真空感應熔融之爭議的一項發 〇 展爲經由噴嘴從冷的爐床熔融系統的床底傾倒。參見頒予 Rowe之美國專利第4,546,85 8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慣例的好 處’但是噴嘴的使用不完全沒有複雜化的可能性。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 200940208 致力提供必要的液體流速控制、減至最低的噴嘴侵蝕及減 至最低的熔融污染。 已用於提出先前所述以真空感應熔融之爭議的另項 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 5,275,229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 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，雖然有該等優勢，但是仍對有用於熔融高反應 性金屬合金（諸如TiAl)之改進系統有需要，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】 @ 本文的具體實施例槪括關於用於離心鑄造高反應性鈦 金屬之系統，其包含一冷壁感應坩堝爐，用於容納鈦金屬 進料，該感應坩堝爐具有數個感應線圈及可移除之底板； 一動力源，用於加熱在感應坩堝爐中的鈦金屬進料，以獲 得熔融金屬；一預加熱之第二坩堝爐，用於捕獲在可移除 之底板已撤除及動力源關閉之後從感應坩堝爐落下之熔融 金屬；及一離心鑄造機，用於固定及加速第二坩堝爐，以 離心迫使熔融金屬至鑄造模具中及製造鑄件。 -8- .200940208 本文的具體實施例亦槪括關於用於離心鑄造高反應性 鈦金屬之系統，其包含一冷壁感應坩堝爐’用於容納鈦金 屬進料，該感應坩堝爐具有數個感應線圈及可移除之底 板；一動力源，用於加熱在感應坩堝爐中的鈦金屬進料’ 以獲得熔融金屬；—預加熱之第二坩堝爐’用於捕獲在可 移除之底板已撤除及動力源關閉之後從感應坩堝爐落下之 溶融金屬；一漏斗，用於從感應坦渦爐轉移溶融金屬至第 II 二坩堝爐；及一離心鑄造機，用於固定及加速第二坩堝 爐，以離心迫使熔融金屬至鑄造模具中及製造鑄件。 具體實施例亦槪括關於用於離心鑄造高反應性鈦金屬 之系統，其包含一冷壁感應坩堝爐，用於容納鈦鋁化物進 料，該感應坩堝爐具有數個感應線圈及可滑動移除之底 板；一動力源，用於加熱在感應坩堝爐中的鈦鋁化物進 料，以獲得熔融鈦鋁化物；一預加熱之第二坩堝爐，用於 捕獲在可移除之底板已撤除及動力源關閉之後從感應坩堝 〇 爐落下之熔融鈦鋁化物；一鈮漏斗，用於從感應坩堝爐轉 移熔融鈦鋁化物至第二坩渦爐；及一離心鑄造機，使第二 坩堝爐在熔融鈦鋁化物落入第二坩堝爐之後維持從約0.5 至約2秒之靜態；及隨後使第二坩堝爐在從約1秒至約2 秒之內加速至從約100 rpm至約600 rpm，以離心迫使熔 融鈦鋁化物至鑄造模具中及製造鑄件。 從下列的揭示內容使得這些及其他特點、觀點及優勢 爲那些熟習本技藝者所明白。 200940208 【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 屬之系統’且特別爲欽合金及欽銘化物合金，經由隨後但-不應被限制於此的所敘述之該系統鑄造成網狀鑄件。 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熔融之銅。更特別地，銅通常在約 U 1 900°F (約 1 038T：)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 〇 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 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熔融及維持其熔融 態。另外，電絕緣板19可圈限底板16，有助於維持在坩 -10- .200940208 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 入坩堝爐10的爐體12內部，如圖1中所示。在一個具體 實施例中’金屬進料18可包含鈦合金，且更特別爲鈦鋁 化物合金，並可呈任何可接受之形式，其可包括，但不限 φ 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1.25磅（約567公克）至約3.3 磅（約1497公克）金屬進料18製備成網狀之低壓渦輪葉 片，如下文所述。 一旦將金屬進料18放入坩堝爐1〇內部時，可將在一 ❹ 個具體實施例中可從與坩堝爐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10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 T至約2835 °F (約1480 °C至約1557 °C)。那fe熟習本枝藝者將瞭解由感應線圈所產生的電石炫 場引起金屬進料本身內部加熱’其係由於對抗在金屬進料 內的電流所引起的加熱。當金屬進料1 8開始熔融時’則 所得熔融金屬30可變成懸浮在祖渦爐丨〇的爐體^2內’ -11 - 200940208 使得熔融金屬30不與爐體12內部接觸，只要將動力施予 坩堝爐1〇。該熔融金屬30懸浮液可避免形成凝殻。 與金屬進料在坩堝爐10中熔融的同時，可將第二坩 - 堝爐32或其他類似的固定裝置使用任何可接受之方式預 加熱，諸如但不限於微波或輻射能量。第二坩堝爐可從石 墨或陶瓷製成，並可選擇地具有金屬襯墊，諸如鈮。第二 坩堝爐32可協助溶融金屬轉移至鑄造模具中，而不損失 任何在感應坩堝爐10中的感應熔融期間所產生之熔融金 Q 屬中的過熱。更特別地，當第二坩堝爐32包含鈮時，貝IJ 可將第二坩堝爐32預加熱至至少約1832°F (約l〇〇〇°C)， 而在一個具體實施例中，從約1 832°F至約2200°F(1000°C 至約1 200 °C )，且當第二坩堝爐包含陶瓷時，則預加熱至 至少約1 980T (約1 082 °C)，而在一個具體實施例中，從 約1 9 80°F至約2400°F( 1 082 °C至約13161)。預加熱可有 助於避免熱衝擊及第二坩堝爐32裂開，可允許其再使 用。接著將預加熱的第二坩堝爐32放入離心鑄造機36的 ◎ 旋轉臂34中及放置在感應坩堝爐10之下，如圖3中的槪 括展示。任何習知的離心鑄造機可接受於本文使用，諸如 Linn High-Therm Titancast 700(德國）或 SEIT Supercast(義大利）。 接著可將可移除之底板16從坩堝爐10的爐體12撤 除，如先前所述。在圖2及3中所示之具體實施例中，可 將底板16使用任何可接受之機件（諸如但不限於軌道或導 軌）從坩堝爐10以滑動移除，雖然底板16被移除，但是 -12- .200940208 由感應線圈14所產生的電磁場可維持熔融金屬30在坩堝 爐10的爐體12內處於懸浮狀態，如圖2中所示，直到進 一步加工爲止。 - 當動力源21關閉時，則允許熔融金屬30從感應坩堝 爐10經由鈮漏斗33落下且落入經預熱之第二坩堝爐32 中，使其在鑄造機36內可維持長至剛好足以使熔融金屬 30完成其轉移至第二坩堝爐32中的靜態，在一個具體實 @ 施例中，其可爲從約0.5至約2秒。一旦熔融金屬30的 轉移完成時，可將第二坩堝爐32迅速（約1至約2秒）加 速至全速，其可從約100 rpm至約600 rpm。鑄造機36可 以離心迫使熔融金屬3 0離開第二坩堝爐3 2及經由通口 40進入鑄造模具38中，該通口可包含狹縫、洞、管或其 組合中之至少一者。從第二坩堝爐32至鑄造模具38中的 該快速轉移造成在少於約5秒的2秒之間的接觸時間。該 短暫的接觸時間不僅顯著地減少熱損失，並亦有助於確保 G 在熔融金屬與建構第二坩堝爐32所使用的石墨或陶瓷之 間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，其提拱 惰性表面塗層及隔熱背襯材料。在一個具體實施例中，作 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、氧 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、氧化鈸、氧化鉅、氧化釤、氧化銪、氧 -13- 200940208 化釓、氧化铽、氧化鏑、氧化鈥、氧化餌、氧化鏡、氧化 镏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、矽酸锆、二氧化 砂及其組合物的耐火材料。 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—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 q 葉片42需要些微的鑄造後加工。由鑄造機36所產生的離 心力係藉由改進膜具的薄片塡充而提供最優化之鑄造模具 3 8塡充，藉此提供網狀鑄件。 而且，因爲冷壁坩堝爐被用於熔融金屬進料，所以在 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， 熔融金屬有來自坩堝爐破裂之污染的可能性減低。較少的 Q 污染可造成改進的鈦合金之機械特性。 該書面說明書使用實例揭示本發明，包括最以最好的 模式，並亦能夠使任何熟習本技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。 -14- .200940208 【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； 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 意圖； 圖3爲依據本文所述之離心鑄造系統的一個具體實施 Φ 例之橫截面示意圖；及 圖4爲可依據本文所述而鑄造之低壓渦輪葉片鑄件之 立體示意圖。 【主要元件符號說明】 10:冷壁感應坩堝爐 12 :爐體 14 :線圈 φ 16:可移除之底板 1 8 :金屬進料 1 9 :電絕緣板 20 :蓋子 21 :動力源 22 :蓋環 24 :水冷卻入口 2 6 :水冷卻出口 28 :通道 -15- 200940208 3 0 :熔融金屬 3 2 :第二坩堝爐 33 :漏斗 34 :旋轉臂 3 6 :鑄造機 3 8 :壽造模具 40 :通口 42 :低壓渦輪葉片BACKGROUND OF THE INVENTION 1. The specific embodiments described herein include systems for centrifugally casting highly reactive metals. More particularly, specific embodiments herein describe systems for centrifugally casting highly reactive titanium alloys, particularly titanium aluminide alloys. U [Prior Art] Turbo engine designers are continually looking for new materials with improved features that reduce engine weight and achieve higher engine operating temperatures. Titanium alloys (Ti alloys) and especially titanium aluminide-based alloys (TiAl alloys) have low-temperature mechanical properties such as room temperature ductility and toughness' and a promising combination of medium-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. φ Vacuum Arc Remelting (VAR) is a technique commonly used to melt Ti alloys. The VAR typically contains an arc that strikes between a titanium alloy electrode placed in a water cooled copper crucible furnace 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 the mold used to cast 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 cost labor involved in producing the electrode from the certified waste and return material. Moreover, the requirements for the pre-5-200940208 alloy electrode make it difficult to produce a non-standard alloy at a high price. In addition, the need for furnaces that use water cooling can limit the degree of superheat that can be achieved in metals, which in turn can affect flow, resulting in difficulties in filling thin wall castings. Moreover, the highest temperature exists where the arc strikes the metal and a high temperature gradient is present 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). The development of VIM is used 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, VIM 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 developed solid titanium "capsules contain 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 furnace life and results in -6-200940208 impurities in the cast casting. Moreover, the highly reactive TiAl alloy can rupture the ceramic crucible and contaminate the titanium alloy with both oxygen and refractory alloys from the oxide. Similarly, if a graphite crucible is used, the titanium aluminide can dissolve a large amount of carbon from the -tan 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 crucibles, which is why φ copper beryllium furnaces are typically used to melt highly reactive metal alloys when cold wall induction melting is used. However, while the cold head melting in a copper crucible furnace can give the metallurgical advantages of the previously described highly reactive alloy processing, it can also have many technical and economic constraints, including low overheating, due to the formation of agglomerates. Loss of rate and high power demand. In particular, the cold wall induction furnace suffers heat loss when the power of the crucible is stopped and the metal is allowed to sink against the water-cooled copper surface of the mold. One development that has been used to address 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. 4,546,85, to the name of U.S. Pat. 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. While the use of nozzles offers many advantages over other common practices, the use of nozzles is not completely without the possibility of complications. For example, cold hearth melting of reactive metals such as titanium and bed bottom dumping can cause undesirable melt solidification in the nozzle. In addition, many furnace/nozzle systems are available to provide the necessary liquid flow control, minimize nozzle erosion and minimize melt contamination. Another development that has been used to address the previously discussed controversy of vacuum induction melting has been the development of suspension melting, which typically involves the use of energy from an induction coil to electromagnetically suspend molten metal. See U.S. Patent No. 5,275,229, 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 slip back into the water-cooled crucible and re-start before it is dumped. cold. This can result in incomplete mold filling. Thus, despite these advantages, there is a need for an improved system for melting highly reactive metal alloys, such as TiAl, which allows the alloy to remain molten during pouring and also reduces controversy associated with conventional melting processes. appear. SUMMARY OF THE INVENTION @ The specific embodiments herein include a system for centrifugally casting highly reactive titanium metal, comprising a cold wall induction crucible for containing a titanium metal feed having a plurality of inductions a coil and a removable bottom plate; a power source for heating the titanium metal feed in the induction crucible to obtain molten metal; and a preheated second crucible for capturing the removable bottom plate The molten metal dropped from the induction crucible after the power source is turned off; and a centrifugal casting machine for fixing and accelerating the second crucible, centrifugally forcing the molten metal into the casting mold and manufacturing the casting. -8-.200940208 Specific embodiments herein also include a system for centrifugally casting highly reactive titanium metal comprising a cold wall induction crucible for containing a titanium metal feed having a plurality of induction furnaces Induction coil and removable bottom plate; a power source for heating the titanium metal feed in the induction furnace to obtain molten metal; - a preheated second furnace for capturing the removable bottom plate The molten metal that has been removed from the induction furnace after the power source is turned off; a funnel for transferring molten metal from the induction furnace to the second furnace; and a centrifugal casting machine for fixing and accelerating the second crucible The furnace centrifugally forces the molten metal into the casting mold and manufactures the casting. Specific embodiments also include a system for centrifugally casting highly reactive titanium metal comprising a cold wall induction crucible for containing a titanium aluminide feed having a plurality of induction coils and slidable In addition to the bottom plate; a power source for heating the titanium aluminide feed in the induction crucible to obtain molten titanium aluminide; a preheated second crucible for capture on the removable bottom plate has been removed And a molten titanium aluminide falling from the induction crucible after the power source is turned off; a funnel for transferring molten titanium aluminide from the induction crucible to the second crucible; and a centrifugal casting machine to make the second crucible Maintaining static from about 0.5 to about 2 seconds after the molten titanium aluminide falls into the second furnace; and subsequently accelerating the second furnace from about 1 rpm to about 2 seconds from about 100 rpm to about 600 The rpm is used to force the molten titanium aluminide into the casting mold by centrifugation and to manufacture the casting. These and other features, aspects, and advantages will become apparent to those skilled in the art from the following disclosure. 200940208 [Embodiment] The specific embodiments described herein include a system for centrifugally casting highly reactive metals 'and particularly alloys and alloys, which are described below, but should not be limited thereto. The system is cast into a mesh casting. According to the following description, a cold wall induction crucible 10 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 thermal and electrical conductivity, such as copper. The furnace body 12 can be cooled by water to avoid melting of the copper during heating of the crucible. More particularly, copper typically melts at about U 1 900 °F (about 1 038 T:) and TiAl melts at about 2600 ° F (about 1427 ° C), and the copper in the crucible can form a low titanium. Eutectic. This can be avoided by cooling the oven with water. Water cooling inlet 24 and outlet 26 may be used to circulate cooling water through a plurality of passages 28 disposed about 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 induction coils 14 placed around it that can be heated using a power source 21. Coil 14 can be used as a source of heat 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 16 can also be water cooled and have a plurality of induction coils 14 placed thereunder to assist the placed metal feed to melt and maintain its molten state in the crucible 10. In addition, the electrically insulating plate 19 can enclose the bottom plate 16 to help maintain heat at the bottom of the crucible 10 of the 坩-10-.200940208. 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, a metal feed 18 comprising a highly reactive alloy can be placed inside the furnace body 12 of the crucible 10, as shown in Figure 1. In a particular embodiment, 'metal feed 18 may comprise a titanium alloy, and more particularly a titanium aluminide alloy, and may be in any acceptable form, which may include, but is not limited to, agglomerates, ingots, particles, Plates, powders 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 embodiment, from about 1 pound (about 454 grams) to about 3.5 pounds can be used. (about 1588 grams), while in another embodiment, a low pressure turbine blade can be prepared from about 1.25 pounds (about 567 grams) to about 3.3 pounds (about 1497 grams) of metal feed 18, as follows Said. Once the metal feed 18 is placed inside the crucible, a lid 20 made of the same material as the crucible can be placed on top 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 10 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 T to about 2835 °F (about 1480 ° C to about 1557 ° C). . Those skilled in the art will understand that the sap of the carbide generated by the induction coil causes internal heating of the metal feed itself, which is due to the heating caused by the current in the metal feed. When the metal feed 18 begins to melt, the resulting molten metal 30 can become suspended in the furnace body 2 of the vortex furnace ' -11 - 200940208 so that the molten metal 30 does not contact the inside of the furnace body 12, as long as the power is Give the furnace 1 〇. The molten metal 30 suspension avoids the formation of a crust. While the metal feed is being melted in the crucible 10, the second crucible 32 or other similar fixture may be preheated using any acceptable means such as, but not limited to, microwave or radiant energy. The second crucible can be made of graphite or ceramic and optionally has a metal liner such as a crucible. The second crucible 32 assists in the transfer of molten metal into the casting mold without any loss of superheat in the molten gold genus generated during induction melting in the induction crucible 10. More particularly, when the second crucible 32 contains crucibles, the second crucible 32 can preheat the second crucible 32 to at least about 1832 °F (about 10 ° C), and in one particular embodiment, from From about 1 832 °F to about 2200 °F (1000 °C to about 1 200 °C), and when the second furnace contains ceramics, it is preheated to at least about 1 980T (about 1 082 °C), and In one embodiment, from about 1 980 °F to about 2400 °F (1 082 °C to about 13161). Preheating can help avoid thermal shock and the second furnace 32 is cracked, allowing it to be reused. The preheated second crucible 32 is then placed in the rotative arm 34 of the centrifugal casting machine 36 and placed under the induction crucible 10, as shown in Fig. 3. Any conventional centrifugal casting machine can be used herein, such as Linn High-Therm Titancast 700 (Germany) or SEIT Supercast (Italy). The removable bottom panel 16 can then be removed from the furnace body 12 of the crucible 10 as previously described. In the particular embodiment illustrated in Figures 2 and 3, the bottom plate 16 can be slidably removed from the crucible 10 using any acceptable mechanism, such as, but not limited to, a track or rail, although the bottom plate 16 is removed, However, 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 Figure 2, until further processing. - When the power source 21 is turned off, the molten metal 30 is allowed to fall from the induction crucible 10 via 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 30 is allowed to complete its transfer to the static state in the second crucible 32, which in a particular embodiment may range from about 0.5 to about 2 seconds. Once the transfer of molten metal 30 is complete, the second furnace 32 can be accelerated 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 can centrifugally force the molten metal 30 away from the second furnace 3 2 and into the casting mold 38 via the port 40, which can include at least one of a slit, a hole, a tube, or a combination thereof. This 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 brief contact time not only significantly reduces heat loss, but also helps to ensure that G does not have any undesirable reaction between the molten metal and 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 one embodiment, the casting mold 38 as an example may comprise a surface coating comprising an oxide. As used herein, the term "oxide" refers to a composition selected from the group consisting of cerium oxide, cerium oxide, oxidizing, cerium oxide metal, and combinations thereof. In addition, the lanthanum oxide metal (also referred to as "rare earth metal ruthenium composition) may comprise cerium oxide, cerium oxide, cerium oxide, cerium oxide, oxidized giant, cerium oxide, cerium oxide, oxygen-13-200940208 An oxide of cerium oxide, cerium oxide, cerium oxide, oxidized bait, oxidizing mirror, cerium oxide and combinations thereof. The casting mold 38 can comprise a backing comprising a refractory material selected from the group consisting of alumina, zirconium silicate, silica, and combinations thereof in a colloidal ceria suspension. 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 a particular embodiment, the casting can be a low pressure turbine blade 42' as shown in Fig. 4. Because centrifugal casting is used, the q blade 42 requires a slight post-casting process. The centrifugal force generated by the casting machine 36 provides an optimized casting mold by improving the sheet filling of the film, thereby providing a mesh casting. Moreover, because the cold wall crucible is used for the molten metal feed, there is less thermal stress on the crucible, and thus less crucible 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 the molten metal has contamination from the collapse of the crucible is reduced. Less Q 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 examples have structural elements that do not differ from the literal language of the scope of the patent application, or if they include equivalent structural elements that are not substantially different from the literal language of the claimed patent, the application is intended to be Within the scope of the patent. -14- .200940208 [Simplified illustration of the drawings] Fig. 1 is a schematic cross-sectional view of a specific embodiment of a cold wall induction crucible having a metal feed placed therein, according to the description herein; A cross-sectional schematic view of one embodiment of a cold wall induction crucible having a removed bottom plate and molten metal suspended therein; FIG. 3 is a cross-sectional schematic view of one embodiment of a centrifugal casting system in accordance with the present disclosure; 4 is a perspective view of a low pressure turbine blade casting that can be cast in accordance with the teachings herein. [Main component symbol description] 10: Cold wall induction furnace 12: Furnace body 14: Coil φ 16: Removable bottom plate 1 8: Metal feed 1 9: Electrical insulation plate 20: Cover 21: Power source 22: Cover Ring 24: Water-cooled inlet 2 6 : Water-cooled outlet 28 : Channel - 15 - 200940208 3 0 : Molten metal 3 2 : Second furnace 33 : Funnel 34 : Rotating arm 3 6 : Casting machine 3 8 : Die making mold 40 : Port 42: Low Pressure Turbine Blades
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