1362683 九、發明說明： 【發明所屬之技術領域】 本發明係關於使用為例如液晶顯示裝置背光源的營光 放電管之放電電極及其電極材。 【先前技術】 液晶顯示裝置中的背光源係使用小型螢光放電管。該螢 光放電管係如圖3所示，具備有：在内壁面上形成螢光膜 (未圖示），並在其内部封入放電用氣體（氬氣體等稀有氣 >體及水銀蒸氣）的玻璃管51，以及設置於該玻璃管5丨内 部二端且構成一對冷陰極的放電電極52。上述放電電極 52係具有一端呈開口狀的管部53 ’而上述管部53另一端 .則利用端板部54封閉的杯狀（有底筒狀）形態。上述端板 部54將熔接著軸狀支撐導體55(其係貫穿上述玻璃管 端部並密封）一端，在該支撐導體55另一端將耦接著導線 57。一般上述支撐導體55係由w(鶴.）所形成，通常將與 >放電電極52雷射熔接。 上述放電電極52習知係由純Ni所形成，且尺寸係背光 源等小型螢光放電管用，呈現内徑丄.5咖左右、總長5關 左右、官部53壁厚〇. imm左右。該放電電極通常係藉由 將具有與上述管部壁厚相同厚度的純Ni薄板，施行深轉 成形而一體成形。 如上述螢光放電管用放電電極係由成形性良好且材質 f定的純Ni所形成，但是將有燈泡壽命較短的問題。換 。之田螢光放電管點亮之際，離子等將衝撞電極並產生 312ΧΡ/^Β^Β^9(^ίψ)/95-10/9512030ΐ , 1362683 從電極金屬釋放出原子的現象（濺鍍）<3因為此種濺鍍便將 消耗電極金屬，且所釋放出的電極金屬原子將與玻璃管内 所封入的水銀相結合，而消耗玻璃管内的水銀蒸氣。習知 形成電極金屬的Ni在濺鍍時的原子釋放量頗多，換言之 濺鍍率較尚，因而水銀消耗較大，所以將浮現放電管壽命 容易降低的問題。 所以，近年如日本專利特開2002-1 10085號公報（專利 文獻1)所記載，有嘗試將放電電極由濺鍍率較低的Nb(鈮） •形成。然而，Nb相較於之下係屬高單價。且，肋係屬 於咼融點（2793。〇,當與同屬高融點金屬w(融點3653t：) 的支撐導體進行熔接之際，將需要依高溫施行熔接。所 以，在熔接部將容易形成牢固的氧化膜◊若在該氧化膜附 著的狀態下，將支撐導體所熔接的放電電極密封於玻璃管 内在放電中便會將氧化膜分解而產生氧。該氧便將與管 内面的螢光膜產生反應，導致螢光膜劣化。因此，在支撐 籲導體熔接後，便必需施行將電極表面上所形成氧化膜去除 的步驟。 所以，近年有如日本專例特開2002-2891 38號公報（專 利文獻2)中段落〇〇24、或國際公開w〇2〇〇5/〇48285號公 報（專利文獻3)中所記載，嘗試將放電電極由内外二層形 成，外層係由Ni形成，而實質具放電作用的内層則由Nb 形成。上述專利文獻3中所記載的二層構造放電電極之製 造方法，係將由Ni形成的基層用金屬片、與由Nb形成的 表層用金屬片施行壓接，再將該壓接材施行擴散退火而形 312XP/發明說明書(補件)/95-10/95120301 6 1362683 成包覆材，從該包霜;y* u β # 匕復材如取胚材，並將其深轉成形為杯狀。 專利文獻1:日本專利特開2002-1 1 0085號公報 •專利文獻2:日本專利特開2002-289138號公報 專利文獻3:國際公開W02005/048285號公報 ' 【發明内容】 '(發明所欲解決之問題） 當上述包覆材製造之際’必需將上述壓接材的基層與表 層施打擴散退火’但是因為Nb屬於非常容易氧化的材 料因而通韦壓接材均利用真空加熱爐施行批次退火。換 吕之’壓接材係裝入真空加熱爐中，並將爐内抽真空之 後，再升溫至既定溫度，並保持於該溫度下。此情況下， 因為加熱環境屬於真空，因而升溫速度較慢，即使縮短在 目標退火溫度下的保持時間，但是在到達目標退火溫度的 過程中、或從目標退火溫度開始進行冷卻的過程中，暴露 於800 C以上高溫區域中的時間仍將拉長。因而必然在基 鲁層與表層之間生成成長出NiNb金屬間化合物。當NiNb金 屬間化合物層較薄時，二層的接合性雖不致造成問題但 疋若金屬間化合物層厚度達某程度時，在施行深轉成形之 際，便將在此處出現龜裂狀況，導致於成形之際表層將無 法追循基層的變形，恐將在表層上出現龜裂狀況。 … 另一方面，當使用連續退火爐將壓接材施行擴散退火 時，朝目標退火溫度的升溫、與退火後的降溫均較快速， 將可抑制N i Nb金屬間化合物層過度成長。此情況下，實 用上必需將爐内環境設定為Ar氣體環境。但是，經發明 312ΧΡ/發明說明書(補件)/95-10/95120301 7 =的只驗中传知’通常在Ar氣體環境（露點 轉成形之際將有…中出現龜裂:狀) 况’特別係4形條件較為料的話，龜 另外’加熱環境氣體將無法使軌氣、氫氣。理m tNb形成氮化物，而氫則容易被Nb吸收，二者情況均將 導致Nb層脆化、成形性劣化。 本發明係有鑑於該箄問薜& & —丄、# „ 发寻問喊而所完成，其目的在於提供一 種形成杯狀放電電極的深赫士、a 7SL u > a 电裡幻冰轉成形性優越之包覆材及其製 造方法，以及利用該包覆材所成形的放電電極。八 (解決問題之手段） 本發明的放電電極用包覆材係具備有：由純Ni或以Ni 為主成刀的Ni基合金所形成基層、以及由純⑽所形成表 層，而上述表層係在未隔著NiNb金屬間化合物層的情況 下、或隔著NiNb金屬間化合物層的情況下，擴散接合於 上述基層上；將形成上述表層的純Nb中之氧含有量設定 在550ppm以下，將上述NiNb金屬間化合物層的層厚度設 定在8.0//m以下。 依知、該包覆材’因為表層係由氧含有量55〇ppm以下的 純Nb所形成，因而延展性將優越。且，上述表層係直接、 或隔著較難發生龜裂的8. Oym以下NiNb金屬間化合物 層’擴散接合於基層，因此上述基層與表層間之接合性將 優越。結合該優越接合性與表層的優越延展性，便將使包 覆材具優越深轉性。 上述基層與表層最好利用在露點-4〇。(：以下的Ar氣體 312XP/發明說明書(補件)/95.10/95120301 8 1362683 環境中施行連續退火而擴散退火。藉由該連續退火便可在 麵易的將被表層所吸收氧量抑制到55〇ppm以下的情況 .下，將基層與表層效率佳的施行擴散接合，因而包覆材的 生產性將優越。 再者，上述基層最好由單獨、或複合含有肋、以在 l.Omass%以上、且i2.〇mass%以下，其餘則為Ni及不可 ，，的不純物所構成Ni基合金形成。藉由在Ni中添加既 疋里Nb、Ta，便可提升對水銀蒸氣的耐蝕性，將可提升 攀放電電極的耐久性。 再者，上述表層最好厚度20/zm以上、且1〇〇#m以下。 藉由將表層厚度設定在20//m以上、且1〇〇wm以下，便 可使用較少量的Nb，確保與整體由純肋所形成放電電極 為同等級的壽命。所以，將可降低包覆材的材料成本頗 具經濟性。 再者，最好將表層厚度相對於上述基層與表層的合計厚 镰度設定在7〇%以下。藉由依此設定表層厚度，當施行杯狀 放電電極成形之際，便可使基層產生表層之支撐層的作 •用。藉此，便可防止在由降伏點延伸較大的Nb所形成表 層上發生因魯德氏曲線（Luders’ band)所造成的凹凸現 象，將可確保良好的壓鑄成形性。若表層厚度超過合計厚 度的70%，即便將基層設計為支撐層，仍頗難抑制上述凹 凸狀況的發生，反將導致壓鑄成形性降低。所以，表層厚 度相對於合計厚度之下，最好設定在7〇%以下，尤以 以下為佳。 ° 312ΧΡ/發明說明書(補件)/95-10/95120301 9 1362683 • . , * 再者，本發明的放電電極係具備有：一端呈開放的管 部、以及將上述管部另一端封閉的端板部，並將上述管部 •與端板部利用壓鑄成形而一體製造的放電電極；其中，上 •述放電電極係由上述包覆材所成形，上述管部及端板部内 層係由上述包覆材的表層所形成。因為該放電電極係使用 深轉成形性優越的上述包覆材成形，因而生產性優越且 將可節省對放電無助盈的仙量使用，因而將可降低材料 成本。且因為在端板部外侧將存在由純Ni等所形成的美 ♦層，因而與支樓導體間之炫接性亦將呈良好狀態。土 再者，本發明放電電極用包覆材之製造方法係包括有： 將由純Νι或以Νι為主成分的Ni基合金所形成基層用金 屬片、與由純Nb所形成表層用金屬片重疊並壓接，而製 成基層與表層相壓接之壓接材的壓接步驟；以及將上述壓 接材在露點-40°C以下的Ar氣體環境中，於8〇〇〜11〇(Γ(： 退火溫度區域中保持15秒以上、12〇秒以下，而將上述 _基層與表層施行擴散接合的擴散退火步驟。 依照該製造方法，即使使用連續退火爐將壓接材的基層 與表層施行擴散接合，仍可輕易的將包覆材表層的氧含有 •量降低至550PPm以下，且可將在表層與基層之間所產生 .NiNb金屬間化合物層厚度抑制在以下。所以，將 •可輕易製造出深轉性優越的包覆材，且生產性優越。 在該製造方法中，上述基層係可自Ni基合金形成，該 Νι基合金係含有Nb或Ta中之一種或二種合計在 1. Omass%以上、且12. 〇mass%以下，而其餘則為M及不 312XP/發明說明書(補件)/95-10/95120301 1362683 可避免的不純物。此外’尚可設計：對上述經擴散退火的 包覆材施行精軋，而調整上述包覆材厚度的精軋步驟。 【實施方式】 圖1所不係本發明實施形態的放電電極用包覆材剖視 圖，該包覆材係具備有：由純Ni或以Ni為主成分的Ni基 合金所形成基層1 '以及由純Nb所形成表層2 ;上述表層 2係輥壓接於上述基層1上，然後再施行擴散接合。上述 表層2係隔個8.0/zm以下的極薄NiNb金屬間化合物層， 擴散接合於基層1上，在圖1中並未圖示該NiNb金屬間 化合物層。針對該金屬間化合物層，容在後述該包覆材之 製造方法的說明中進行說明。 开> 成上述基層1的純N i、N i基合金（以下將該等統稱為 「Ni基金屬」）係耐氧化性優越，且冷軋加工性亦優越， 深轉性亦良好。上述Ni基合金最好由Ni量在8〇mass%a 上（尤以85mass%以上為佳），且含有能與Ni產生固熔的 合金元素（例如Nb、Mo、W、Ta、V、Ti)中一種以上，其 餘Ni及不可避免的不純物所構成。上述Ni基合金内，尤 以單獨或複合含有Nb、Ta在1. (M2. Omass%，其餘則為 Ni及不可避免的不純物所構成的Ni-Nb合金、Ni-Ta合 金、Ni-Nb-Ta合金為佳。若Nb、Ta設定為此程度的添加 量，便不致損害及成形性’且具有提升對水銀蒸氣耐蝕性 的效果’將可提升電極耐久性❶此外，W含有 2. 0〜lOmass%’其餘則實質為Ni所構成的Ni-W合金為佳。 W亦將如同Nb、Ta ’將可提升對水銀蒸氣的耐蝕性。亦可 312XP/發明說明書(補件)/95-10/95120301 11 1362683 複合添加w與上述含有範圍内的Nb及/或Ta，惟此情況 下的w量最好限制於6. 0%程度以下。 〜上述表層2係由純Nb所形成，而較容易被Nb所吸收（固 /合）的氧、氫、氮等氣體係越少越好。如後述，該包覆材 在工業上係將構成各層素材的金屬片施行重疊並壓接之 後，再將所獲得壓接材於Ar氣體環境中施行退火便可進 =製造，此情泥下’ Ar氣體中所含水分將在高溫中產生 刀解而所產生的氧恐將被Nb所吸收。若吸收氧使此中 ，的氧量超過55一的延展性便將明顯劣二 ;兄將導致包覆材的深轉成形性劣化。所以，本發明便將形 成表層的、，，屯Mb中之氧濃度限制於55〇ppm以下，最好 OOppm以下。另外，因為純Nb係利用真空溶解法而進行 製造，因而所製得·純Nb+的氧含有量將在2〇〇卿程 下。 、上述表層2的厚度若就從放電電極的消耗形態觀之，將 丨’、、肩在20 // m左右，但是若考慮安全性、包覆材整體厚度 的均衡性，便最好設定為2〇〜1〇〇"m左右，尤以4〇，" 左右為佳。另一方面，為能確保深轉成形性，便將包覆材 ^體厚度設定在〇.卜〇· 2mm左右。上述基層^的厚度，係 、7<考慮上述表;f 2厚度而適當設定能確保上述整體厚 度，就從確保支撐電極炼接性的觀點，則20〜50"左右 ，已足夠。此外’為使上述基層1產生防丘表層2變形用 厚a、的作用i A確保深轉成形之際的良好塵禱成形 …上述表層2厚度最好設定為表層2與基層i的合計厚 3^xp/memmmm/95.i〇/95i2〇3〇i n 1362683 度（包覆材整體厚度）的70%以下，尤卩6〇%以下為佳。 圖2所示係使用上述包覆材施行轉成形的杯狀放電 電極。該放電電極係具備有：一端呈開放狀態的管部工工、 •以及將另-端封閉的端板部12 ’上述端板部12將與上述 管部11 -體成形。此外’放電電極内層係由上述包覆材 的表層2所形成。當使用為放電電極的情況時因為隨放 電而消耗的部分主要集中於放電電極的底部内面部因而 藉由使放電電極内層由表層2形成，便可在確保僅由肋 所形成放電電極為同等級放電特性、以及螢光放電管使用 哥命的情況下，減少Nb使用量。且藉由基層j的存在， 亦可使與支撐導體間之熔接趨於容易。 上述杯狀放電電極係將從上述包覆材施行沖壓加工而 獲得圓板狀胚材當作成形素材，並經壓鑄成形而施行深轉 成形。當上述胚材施行沖壓加工之際，例如可將其中一部 分利用連結部連結於包覆材外周部，並深轉成形為複數杯 鲁狀放電電極之後，再從連結部分離出放電電極。 .在此針對上述包覆材之製造方法進行說明。首先，在基 -層1原料的…基金屬片（基層用金屬片）上，重疊著表層 .2原料的Nb片（表層用金屬片），並施行輥壓接。換言之， 將N i片與Nb片相重疊而所形成的重疊材，並使其通過一 對輥之間而施行壓接。該壓接係可依冷軋實施。輥壓接時 的輥壓率’通常最好設定為5〇〜左右。將該製造步驟 稱為「壓接步驟」。藉由該壓接步驟，便可獲得基層與表 層相壓接的壓接材。 312XP/發明說明書(補件)/95-10/95120301 13 1362683 其次，上述壓接材將在800~1100〇c左右（最好9〇〇〜1〇5〇 °C)的溫度下施行擴散退火。將該製造步驟稱為「擴散退 火步驟」。若未滿800Ϊ，便較不易產生擴散，反之，若 超過110 0 C ’則擴散將趨於明顯，導致短時間便成長出 在壓接材的基層與表層間之界面上所生成的Ni Mb金屬間 化合物層’且厚度將超過8//m。因為超過8#m的較厚NiNb 金屬間化合物層將非常脆弱、易碎，因而包覆材成形性將 劣化。上述NiNb金屬間化合物層的厚度最好設定在 6. 5ym以下。在上述8〇〇〜：n00〇c溫度區域下應保持的時 間’最好設定為15〜120秒左右。若未滿15秒左右，當將 目標退火溫度設定為800°C左右時，擴散便將不足導致接 合強度降低’恐將造成包覆材成形性劣化。反之，若超過 12 0移左右’當將目標退火溫度設定為11 〇 〇 左右時，擴 散將過度’導致金屬間化合物將明顯的成長，而造成接合 強度降低’終究仍恐將造成成形性劣化。較佳的目標退火 溫度係90(M 050°C左右。 能輕易滿足上述擴散退火條件的退火方法，將推薦加熱 環境為Ar氣體環境的連續退火。上述連續退火係使用連 續退火爐實施。連續退火爐係在隧道爐内，依Ar氣體呈 正壓（較大氣壓高出0.0005〜O.OOIMPa左右的高壓）之方 式進行供應，並沿爐的長度方向，依能獲得所需溫度分佈 的方式施行溫度控制。對該連續退火爐供應被處理材（例 如條帶狀壓接材），藉由朝爐的長度方向依既定搬送速度 進行搬送，並根據搬送速度與預設形成溫度分佈，便可對 312XP/發明說明書(補件)/95·ι〇/95120301 14 1362683 • · 被處理材的處理狀態設定成既定溫度與保持時間。 田施订上述連續退火時，相關本發明中所供應訐氣 •體’將設定為露點在-⑽以下，最好_45t以下。若露點 •超過-4(TC，Ar氣體中所含的水分將增加，該水分在高溫 的退火溫度下將分解，而所生成的氧將被Nb所吸收。所 以’表層的延展性將劣化，造成包覆材成形性降低。藉由 在露點-4(TC以下的Ar氣體環境中，於8〇〇11〇代溫产 區，下將保持時間設定為15〜12〇sec，便可將包覆材的^ 層氧濃度限制於550_以下，便可抑制表層延展性劣化 狀況。 上述壓接材的擴散退火係可在真空下實施。尤其是為將 形成表層2的純Nb中之氧量設定在55〇卿以下，最好採 取滿足上述退火條件的加熱冷卻方法。其中一例係可採取 下述真空加熱方法。使用在處理室内設有加熱裝置的真空 處理室，將被處理物收納於真空處理室中，並將處理室; _。卩形成真空之後，再利用上述加熱裝置將被處理物迅速加 熱至既定溫度並保持，當施行冷卻之際便停止加熱，且對 •真空處理室内導入紅氣體而迅速冷卻。若在真空下施行 •擴散退火’在基層1與表層2之間將幾乎不生成NiNb金 屬間化合物層，可將表層2直接擴散接合於基層！上。 經擴散退火後的包覆材視需要亦可利用冷軋施行精 乾。藉此便可調整包覆材的板厚。此外，精乳後，為使材 質軟化，視需要亦可依如同上述擴散退火的相同條件施行 退火。依上述所製得包覆材將視需要切取成適當寬度，更 312XP/發明說明書(補件)/95· 10/95120301 15 1362683 將所切取的帶材施行沖壓加工成胚材，再將該胚材提供給 壓鑄成形》 . 以下’舉實施例針對本發明進行更具體說明，惟本發明 不能解釋為僅侷限於該等實施例。 (實施例） 依以下要領製作出在由純Ni所形成基層上依各種條 件擴散接合著由純Nb所形成表層的各種包覆材試料。準 備基層原料的純Ni片（寬度30mm、長度1 〇〇mm、厚度 • 0. 5mm)、及表層原料的純Nb片（寬度3〇隨、長度1〇〇咖、 厚度0. 15mm)，並將其重疊且依冷軋施行輥壓接，依此便 獲得厚度0.28mm壓接片。將該壓接片通過Ar氣體環境的 連續退火爐，並依表1所示各種條件施行擴散退火，再對 所獲得各包覆材施行冷軋壓延，俾將各包覆材厚度調整為 0. 15mm(基層厚度〇. 114mm、表層厚度〇. 〇36mm)。此外， 相關其中一部分壓接片，利用真空爐依表丨所示條件施行 #批次退火，再將所獲得包覆材依形成上述厚度的方式施行 冷軋壓延。 將依上述所製成各包覆材試料埋入於樹脂中，再將所獲 _得樹脂塊施行研磨，俾使所埋藏的包覆材截面裸露出於表 面。然後，針對各包覆材試料，使用電子顯微鏡（倍率 1000〜3500倍），測定在該包覆材基層與表層之間所生成 NiNb金屬間化合物層的平均厚度。此外，從各包覆材中 採取分析片，並利用氧氮分析裝置（型號EMGA_52〇、堀場 製作所製）測量氧含有量。因為基層中的氧量係卜如⑽左 312XP/發明說明書(補件)/95-10/95120301 1362683 ’因此便將所測得氧量視為表層中 測定結果合併整理於表1中。 的氧量。該等1362683 IX. Description of the Invention: TECHNICAL FIELD The present invention relates to a discharge electrode and an electrode material thereof using a camping discharge tube which is, for example, a backlight of a liquid crystal display device. [Prior Art] A backlight in a liquid crystal display device uses a small fluorescent discharge tube. As shown in FIG. 3, the fluorescent discharge tube is provided with a fluorescent film (not shown) on the inner wall surface, and a discharge gas (a rare gas such as argon gas and a body vapor) is sealed inside the fluorescent discharge tube. The glass tube 51 and the discharge electrode 52 which are disposed at the inner two ends of the glass tube 5 and constitute a pair of cold cathodes. The discharge electrode 52 has a tubular portion 53' having an open end and the other end of the tubular portion 53 is formed in a cup shape (bottomed cylindrical shape) closed by the end plate portion 54. The end plate portion 54 will be welded to one end of the shaft-shaped support conductor 55 (which penetrates the end of the glass tube and sealed), and the other end of the support conductor 55 will be coupled to the wire 57. Generally, the above-mentioned support conductor 55 is formed of w (he.), and is usually laser-welded to the > discharge electrode 52. The discharge electrode 52 is conventionally formed of pure Ni, and is used for a small-sized fluorescent discharge tube such as a backlight, and has an inner diameter of about 55, a total length of about 5, and a thickness of about 53 mm. The discharge electrode is usually integrally molded by deep-forming a pure Ni thin plate having the same thickness as that of the above-mentioned tube portion. The discharge electrode for a fluorescent discharge tube is formed of pure Ni having good moldability and a material f, but there is a problem that the life of the bulb is short. Change. When the Shida fluorescent discharge tube is lit, ions and the like will collide with the electrode and produce 312 ΧΡ / ^ Β ^ Β ^ 9 (^ ψ ψ) / 95-10 / 9512030 ΐ , 1362683 phenomenon of atom release from the electrode metal (sputtering) < 3 Because of this sputtering, the electrode metal will be consumed, and the released electrode metal atoms will be combined with the mercury enclosed in the glass tube to consume the mercury vapor in the glass tube. It is known that Ni which forms an electrode metal has a large amount of atomic emission during sputtering, and in other words, a sputtering rate is relatively high, so that mercury consumption is large, so that the life of the discharge tube is easily lowered. Therefore, in recent years, as disclosed in Japanese Laid-Open Patent Publication No. 2002-1 10085 (Patent Document 1), attempts have been made to form a discharge electrode from Nb (铌) having a low sputtering rate. However, Nb is higher than the unit price. Moreover, the rib system belongs to the melting point (2793. 〇, when welding with the supporting conductor of the same high melting point metal w (melting point 3653t:), it is necessary to perform welding at a high temperature. Therefore, it is easy to weld at the welded portion. Forming a strong oxide film, if the oxide film is adhered, the discharge electrode to which the support conductor is welded is sealed in the glass tube, and the oxide film is decomposed to generate oxygen during the discharge. The oxygen will be connected to the inner surface of the tube. The photo film is reacted to cause deterioration of the phosphor film. Therefore, after the support of the conductor is welded, it is necessary to perform a step of removing the oxide film formed on the surface of the electrode. Therefore, in recent years, the Japanese Patent Special Publication No. 2002-2891 38 (Patent Document 2) In paragraph (24), or as disclosed in Japanese Laid-Open Patent Publication No. Hei. No. Hei. The inner layer having a substantially discharge effect is formed of Nb. The method for producing a two-layer structure discharge electrode described in Patent Document 3 is a metal sheet for a base layer formed of Ni and a metal for a surface layer formed of Nb. The sheet is crimped, and then the pressure-bonding material is subjected to diffusion annealing to form a 312XP/invention specification (supplement)/95-10/95120301 6 1362683 into a cladding material from the frosting; y* u β # 匕 composite material For example, Japanese Patent Laying-Open No. 2002-1 190138, Patent Document 2: Japanese Patent Laid-Open No. 2002-289138, Patent Document 3: International Publication W02005/048285 'Summary of the Invention' (Problems to be Solved by the Invention) When the above-mentioned cladding material is manufactured, it is necessary to perform diffusion annealing of the base layer and the surface layer of the above-mentioned pressure-bonding material, but since Nb is very easily oxidized The material of the Tongwei pressure-bonding material is then subjected to batch annealing using a vacuum heating furnace. The pressure-bonding material is replaced by a vacuum heating furnace, and after the furnace is evacuated, the temperature is raised to a predetermined temperature and maintained. At this temperature, in this case, since the heating environment is a vacuum, the heating rate is slow, and even if the holding time at the target annealing temperature is shortened, the cooling is started in the process of reaching the target annealing temperature or starting from the target annealing temperature. During the process, the time exposed to the high temperature region above 800 C will still be elongated. Therefore, NiNb intermetallic compounds are formed between the base layer and the surface layer. When the NiNb intermetallic compound layer is thin, the bonding of the second layer Although the effect does not cause problems, if the thickness of the intermetallic compound layer reaches a certain level, the cracking condition will occur here at the time of deep-forming forming, and the surface layer will not be able to follow the deformation of the base layer at the time of forming. It is feared that cracking will occur on the surface layer. On the other hand, when the pressure-bonding material is subjected to diffusion annealing using a continuous annealing furnace, the temperature rise toward the target annealing temperature and the temperature drop after annealing are both fast, and N i can be suppressed. The Nb intermetallic compound layer is excessively grown. In this case, it is necessary to set the furnace environment to the Ar gas environment. However, according to the invention 312ΧΡ/inventive specification (supplement)/95-10/95120301 7 =, it is known that 'there is usually a crack in the Ar gas environment (the crack will appear in the dew point to be formed). In particular, if the 4-shaped condition is relatively good, the turtle will not be able to make the rail gas or hydrogen by heating the ambient gas. The m tNb forms a nitride, and hydrogen is easily absorbed by Nb, both of which cause the Nb layer to be embrittled and the formability to deteriorate. The present invention has been made in view of the 薜 薜 && - 丄, # „ 发 问 , , , , , , , , , , , , 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 A coating material having excellent ice-formability and a method for producing the same, and a discharge electrode formed by using the coating material. (Resolving the problem) The coating material for a discharge electrode of the present invention is provided with pure Ni or a base layer formed of a Ni-based alloy mainly composed of Ni and a surface layer formed of pure (10), and the surface layer is formed without a NiNb intermetallic compound layer or with a NiNb intermetallic compound layer interposed therebetween And diffusing and bonding to the base layer; setting the oxygen content in the pure Nb forming the surface layer to 550 ppm or less, and setting the layer thickness of the NiNb intermetallic compound layer to 8.0/m or less. 'Because the surface layer is formed of pure Nb having an oxygen content of 55 〇ppm or less, the ductility is superior. The surface layer is directly or interposed with a NiNb intermetallic compound layer below 8. Oym which is less likely to crack. Diffusion bonding to the base layer, Therefore, the bondability between the above-mentioned base layer and the surface layer is superior. Combining the superior bondability with the superior ductility of the surface layer, the cover material is superior in depth. The base layer and the surface layer are preferably used at a dew point of -4 〇. : The following Ar gas 312XP / invention specification (supplement) / 95.10/95120301 8 1362683 The environment is subjected to continuous annealing and diffusion annealing. By this continuous annealing, the amount of oxygen absorbed by the surface layer can be easily suppressed to 55 〇. In the case of a ppm or less, the base layer and the surface layer are efficiently diffusion-bonded, and the productivity of the coating material is superior. Further, the base layer is preferably composed of ribs alone or in combination, and is more than 1.0% by mass. And i2.〇mass% or less, the rest is Ni and not, and the impurities are formed of Ni-based alloy. By adding Nb, Ta to Ni, the corrosion resistance to mercury vapor can be improved. The surface layer preferably has a thickness of 20/zm or more and 1〇〇#m or less. By setting the surface layer thickness to 20//m or more and 1〇〇wm or less, You can use a smaller amount of Nb to ensure The discharge electrode formed by the pure rib is of the same grade life. Therefore, it is economical to reduce the material cost of the cladding material. Furthermore, it is preferable to set the thickness of the surface layer relative to the total thickness of the base layer and the surface layer at 7.7% or less. By setting the thickness of the surface layer accordingly, when the cup-shaped discharge electrode is formed, the base layer can be used as a support layer for the surface layer, thereby preventing a large extension from the drop point. The unevenness caused by the Luders' band on the surface layer formed by Nb will ensure good die-casting formability. If the thickness of the surface layer exceeds 70% of the total thickness, even if the base layer is designed as a support layer, It is difficult to suppress the occurrence of the above-mentioned unevenness, which in turn leads to a decrease in die casting moldability. Therefore, the thickness of the surface layer is preferably set to be less than 7〇% with respect to the total thickness, and particularly preferably the following. ° 312 ΧΡ / invention manual (supplement) / 95-10 / 95120301 9 1362683 • . , * Further, the discharge electrode of the present invention includes a tube portion having one end open, and a terminal closing the other end of the tube portion a plate portion, wherein the tube portion and the end plate portion are integrally formed by die casting; wherein the discharge electrode is formed of the cladding material, and the inner portion of the tube portion and the end plate portion are The surface layer of the cladding material is formed. Since the discharge electrode is formed by using the above-mentioned cladding material having excellent deep-formability, it is excellent in productivity and can be used in a small amount, which can save the cost of discharge, thereby reducing the material cost. Further, since there is a beauty layer formed of pure Ni or the like on the outer side of the end plate portion, the splicing property with the branch conductor will also be in a good state. Further, the method for producing a covering material for a discharge electrode according to the present invention includes: a metal sheet for a base layer formed of a Ni-based alloy containing pure tantalum or Νι as a main component, and a metal sheet for surface layer formed of pure Nb. And crimping, and forming a pressure bonding step of the pressure bonding material with the base layer and the surface layer being pressed; and the pressure bonding material is in an Ar gas environment having a dew point of -40 ° C or less, at 8 〇〇 11 11 〇 (Γ (: a diffusion annealing step of performing diffusion bonding of the above-mentioned base layer and the surface layer in the annealing temperature region for 15 seconds or more and 12 seconds or less. According to the manufacturing method, the base layer and the surface layer of the pressure bonding material are applied even in a continuous annealing furnace. Diffusion bonding can still easily reduce the oxygen content of the surface layer of the cladding material to less than 550 ppm, and the thickness of the NiNb intermetallic compound layer generated between the surface layer and the base layer can be suppressed below. The coating material having superior deep rotation property is produced and has excellent productivity. In the manufacturing method, the base layer may be formed from a Ni-based alloy containing one or two of Nb or Ta in a total of 1 . Omass% Up, and 12. 〇mass% or less, and the rest are M and not 312XP / invention manual (supplement) / 95-10/95120301 1362683 avoidable impurities. In addition, 'can be designed: the above diffusion-annealed package Fig. 1 is a cross-sectional view of a covering material for a discharge electrode according to an embodiment of the present invention, which is provided with a finish rolling, and the covering material is provided by: Ni or a Ni-based alloy containing Ni as a main component forms a base layer 1' and a surface layer 2 formed of pure Nb; the surface layer 2 is roll-bonded to the base layer 1 and then subjected to diffusion bonding. The surface layer 2 is separated The ultra-thin NiNb intermetallic compound layer of 8.0/zm or less is diffusion-bonded to the base layer 1, and the NiNb intermetallic compound layer is not shown in Fig. 1. The intermetallic compound layer is contained in the cladding material described later. In the description of the production method, the pure N i and Ni-based alloys (hereinafter referred to as "Ni-based metals") of the base layer 1 are excellent in oxidation resistance and excellent in cold-rolling workability. , deep rotation is also good. The above Ni-based alloy is best The amount of Ni is 8 〇mass%a (especially preferably 85 mass% or more), and contains at least one of alloying elements (for example, Nb, Mo, W, Ta, V, Ti) capable of solid-melting with Ni, and the remaining Ni And the inevitable impurity is composed of Ni-Nb alloy, Ni which is composed of Nb and Ta alone or in combination with Ni and inevitable impurities. -Ta alloy, Ni-Nb-Ta alloy is preferred. If Nb and Ta are set to such an extent, the effect of not impairing and formability 'and improving the corrosion resistance to mercury vapor' will improve the electrode durability. Further, W contains 2. 0 to lOmass%, and the remainder is preferably a Ni-W alloy composed of Ni. W will also enhance the corrosion resistance to mercury vapor as Nb and Ta'. And the amount of w in the case of the above-mentioned range is preferably limited to 6. 0% or less. . ~ The surface layer 2 is formed of pure Nb, and the gas system such as oxygen, hydrogen, nitrogen or the like which is more easily absorbed (solidified/closed) by Nb is preferably as small as possible. As will be described later, the cladding material is industrially laminated and crimped to form a metal piece constituting each layer of material, and then the obtained pressure-bonding material is annealed in an Ar gas atmosphere to be manufactured. The moisture contained in the Ar gas will be cleaved at high temperatures and the oxygen generated will be absorbed by Nb. If the oxygen is absorbed, the ductility of the oxygen content exceeding 55 is obviously inferior; the brother will cause the deep formability of the cladding material to deteriorate. Therefore, in the present invention, the oxygen concentration in the surface layer is limited to 55 〇 ppm or less, preferably OO ppm or less. Further, since the pure Nb is produced by the vacuum dissolution method, the oxygen content of the pure Nb+ produced will be 2 〇〇. The thickness of the surface layer 2 is about 20 // m from the shape of the discharge electrode. However, considering the safety and the balance of the thickness of the entire cladding material, it is preferable to set it to 2〇~1〇〇"m or so, especially 4〇, " On the other hand, in order to ensure deep-turn formability, the thickness of the covering material is set to about 2 mm. The thickness of the above-mentioned base layer is determined by considering the above-mentioned table; the thickness of f 2 is appropriately set to ensure the overall thickness, and it is sufficient from the viewpoint of ensuring the refining property of the supporting electrode, 20 to 50 " In addition, in order to cause the base layer 1 to generate the thickness a of the anti-mound surface layer 2, the effect i A ensures good dust-pray shaping at the time of deep-turn forming. The thickness of the surface layer 2 is preferably set to be the total thickness of the surface layer 2 and the base layer i. ^xp/memmmm/95.i〇/95i2〇3〇in 1362683 degrees (the overall thickness of the cladding material) is 70% or less, especially preferably 6〇% or less. Fig. 2 shows a cup-shaped discharge electrode which is subjected to transformation molding using the above-mentioned cladding material. The discharge electrode system includes a tube portion having an open end, and an end plate portion 12' that closes the other end. The end plate portion 12 is formed integrally with the tube portion 11. Further, the inner layer of the discharge electrode is formed of the surface layer 2 of the above-mentioned cladding material. When the portion used as the discharge electrode is mainly concentrated on the bottom inner surface portion of the discharge electrode, and thus the inner layer of the discharge electrode is formed by the surface layer 2, it is possible to ensure that the discharge electrode formed only by the rib is of the same level. The discharge characteristics and the use of the fluorescent discharge tube reduce the amount of Nb used. Moreover, by the presence of the base layer j, the fusion with the support conductor can be facilitated. The cup-shaped discharge electrode is obtained by press-forming the above-mentioned cladding material to obtain a disk-shaped blank material as a molding material, and performing deep-drawing molding by die-casting. When the blank material is subjected to press working, for example, one of the portions may be connected to the outer peripheral portion of the covering member by a joint portion, and deep-turned into a plurality of cup-shaped discharge electrodes, and then the discharge electrode may be separated from the joint portion. Here, a method of manufacturing the above-described covering material will be described. First, on the base metal sheet (metal sheet for base layer) of the base-layer 1 raw material, a surface layer of .2 Nb sheet of the raw material (metal sheet for the surface layer) was placed thereon, and roll bonding was performed. In other words, the overlapped material formed by overlapping the N i sheet and the Nb sheet is passed through a pair of rolls to be crimped. The crimping system can be implemented by cold rolling. The roll pressure rate at the time of roll bonding is usually preferably set to about 5 〇. This manufacturing step is referred to as a "crimping step." By the crimping step, the pressure-bonding material in which the base layer and the surface layer are pressed together can be obtained. 312XP/Invention Manual (Supplement)/95-10/95120301 13 1362683 Next, the above pressure bonding material will be subjected to diffusion annealing at a temperature of about 800 to 1100 〇c (preferably 9 〇〇 to 1 〇 5 〇 ° C). . This manufacturing step is referred to as a "diffusion annealing step." If it is less than 800 Ϊ, it will be less prone to diffusion. On the contrary, if it exceeds 110 0 C ', the diffusion will become more obvious, resulting in a short time to grow Ni Mb metal formed at the interface between the base layer and the surface layer of the pressure-bonding material. The inter-compound layer 'and thickness will exceed 8/m. Since the thicker NiNb intermetallic compound layer exceeding 8#m will be very fragile and brittle, the formability of the cladding material will deteriorate. The thickness of the above NiNb intermetallic compound layer is preferably set to 6.5 μm or less. The time □ to be maintained in the above temperature range of 8 〇〇 to :n00 〇 c is preferably set to about 15 to 120 seconds. If the target annealing temperature is set to about 800 ° C or less, if the target annealing temperature is set to about 800 ° C, the diffusion will be insufficient to cause a decrease in the bonding strength, which may cause deterioration of the formability of the cladding material. On the other hand, if the target annealing temperature is set to about 11 〇 ,, the diffusion will be excessive, causing the intermetallic compound to grow significantly, resulting in a decrease in bonding strength. After all, it is feared that the formability is deteriorated. The preferred target annealing temperature is 90 (M 050 ° C. The annealing method can easily meet the above diffusion annealing conditions, and the recommended heating environment is continuous annealing in the Ar gas environment. The above continuous annealing is carried out using a continuous annealing furnace. The furnace is installed in the tunnel furnace according to the positive pressure of the Ar gas (the high pressure is higher than the high pressure of 0.0005~O.OOIMPa), and the temperature control is performed according to the length direction of the furnace according to the desired temperature distribution. The material to be processed (for example, a strip-shaped pressure-bonding material) is supplied to the continuous annealing furnace, and is conveyed at a predetermined conveying speed in the longitudinal direction of the furnace, and the temperature distribution is preset according to the conveying speed and the preset 312XP/ Disclosure of the Invention (Repair)/95·ι〇/95120301 14 1362683 • The processing state of the material to be processed is set to a predetermined temperature and holding time. When the above-mentioned continuous annealing is applied, the helium gas body supplied in the present invention is related. Will be set to a dew point below - (10), preferably below _45t. If the dew point exceeds -4 (TC, the moisture contained in the Ar gas will increase, the moisture is annealed at high temperature The degree will be decomposed, and the generated oxygen will be absorbed by Nb. Therefore, the ductility of the surface layer will be deteriorated, resulting in a decrease in the formability of the cladding material. By the dew point-4 (in the Ar gas environment below TC, at 8) In the 〇〇11〇 generation temperature production zone, the holding time is set to 15 to 12 sec, and the oxygen concentration of the cladding material can be limited to 550 Å or less, thereby suppressing deterioration of surface ductility. The diffusion annealing of the material can be carried out under vacuum. In particular, in order to set the amount of oxygen in the pure Nb forming the surface layer 2 to 55 Å or less, it is preferable to adopt a heating and cooling method which satisfies the above annealing conditions. In the vacuum heating method, a vacuum processing chamber provided with a heating device in a processing chamber is used to store the workpiece in the vacuum processing chamber, and the processing chamber is vacuumed, and then the heating device is used to treat the workpiece. Rapidly heating to a predetermined temperature and maintaining, heating is stopped when cooling is performed, and red gas is introduced into the vacuum processing chamber to be rapidly cooled. If it is performed under vacuum, diffusion annealing is performed between the base layer 1 and the surface layer 2 The NiNb intermetallic compound layer is hardly formed, and the surface layer 2 can be directly diffusion-bonded to the base layer! The diffusion-annealed cladding material can also be subjected to cold-rolling as needed, thereby adjusting the cladding material. In addition, after the fine milk, in order to soften the material, it may be annealed according to the same conditions as the diffusion annealing described above. The coated material prepared according to the above may be cut into an appropriate width as needed, and the 312XP/invention specification ( Replenishment) / 95· 10/95120301 15 1362683 The cut strip is subjected to press working into a blank material, and the blank material is supplied to die casting." The following embodiments are more specifically described for the present invention, but only The invention is not to be construed as being limited to the embodiments. (Example) Various coating material samples in which a surface layer formed of pure Nb was diffused and bonded to each other under various conditions on a base layer formed of pure Ni were produced in the following manner. Prepare pure Ni sheets (width 30 mm, length 1 〇〇 mm, thickness • 0.5 mm) of the base material, and pure Nb sheets of the surface material (width 3 〇, length 1 〇〇 coffee, thickness 0. 15 mm), and This was overlapped and subjected to roll bonding by cold rolling, whereby a crimping piece having a thickness of 0.28 mm was obtained. The crimping piece was passed through a continuous annealing furnace in an Ar gas atmosphere, and diffusion annealing was performed according to various conditions shown in Table 1, and then the obtained cladding materials were subjected to cold rolling calendering, and the thickness of each cladding material was adjusted to 0. 15mm (base layer thickness 114 114mm, surface layer thickness 〇 〇 36mm). Further, a part of the crimping piece is subjected to #bench annealing by a vacuum furnace according to the conditions shown in the table, and the obtained clad material is subjected to cold rolling calendering in such a manner as to form the above thickness. Each of the coated material samples prepared as described above was embedded in a resin, and the obtained resin block was polished to expose the buried cladding material to the surface. Then, the average thickness of the NiNb intermetallic compound layer formed between the cladding layer base layer and the surface layer was measured for each coating material sample using an electron microscope (magnification: 1000 to 3500 times). Further, an analysis sheet was taken from each of the cladding materials, and the oxygen content was measured by an oxygen-nitrogen analyzer (model: EMGA_52〇, manufactured by Horiba, Ltd.). Since the amount of oxygen in the base layer is as shown in (10) left 312XP/invention specification (supplement)/95-10/95120301 1362683', the measured oxygen amount is regarded as the measurement result in the surface layer and is consolidated in Table 1. The amount of oxygen. Such
材中，如表1所示成形結果 將有出現對應包覆材表層 右的微量， 的杯狀放電電極㈣出現碎驗況者。該碎裂絲測在成 形之際，包覆材表層無法追循基層變形而造成斷裂的緣 由表1中得知，發明例的包覆材因為NiNb金屬間化合 物層的平均厚度將限制於6. 以下，且表層氧量亦在 聲38Oppm以下，因而將可獲得優越的深轉成形性。相對於 此’ Ar氣體露點在_35〇c以上的試料N〇. 4及5之包覆材， 表層氧量將達70Oppm以上的過量，導致表層延展性劣 化，使表層出現碎裂狀況。此外’利用真空爐施行退火的 試料No. 3包覆材’因為在800°C以上所保持的時間將無 法避免的拉長，導致金屬間化合物層將過度成長，因而深 轉性將劣化。 312XP/發明說明書(補件)/95.1 〇/95120301 17 1362683 [表1] 試料 No. 擴散退火條件 化合物層平 均厚度 β 01 表層氧量 ppm 成形結果 備註 Ar氣體露點它 目標溫度°匚 800UC以上保 持哮間sec 1 -45 1000 40 1.1 300 良好 發明谷J 2 -45 1000 120 3.2 350 良好 發明例 3 (真空爐） 1000 1800 10 250 碎裂 比較例 4 -20 1000 120 3.0 1100 碎裂 hb 5 -35 1050 180 9. 0 700 碎裂 比較例 B -45 800 20 0.2 280 良好 發明例 / -45 1100 120 6. 5 380 良好 發明例 【圖式簡單說明】 圖1為本發明實施形態的放電電極用包覆材重要部分 剖視圖。 圖2為本發明實施形態的螢光放電管用放電電極縱剖 圖。 圖3為具備習知螢光放電管用放電電極的營光放電與 重要部分縱剖圖。 & 【主要元件符號說明】 1 基層 2 表層 11、 53 管部 12、 54 端板部 51 玻璃管 52 放電電極 55 支撐導體 57 導線 312XP/發明說明書(補件)/95-1〇/95120301 18In the material, as shown in Table 1, there will be a small amount of the cup-shaped discharge electrode (4) corresponding to the right side of the cladding material. The cracking wire was measured at the time of forming, and the surface of the cladding material could not follow the deformation of the base layer to cause fracture. It is known from Table 1 that the coating material of the invention example is limited to 6. Hereinafter, the amount of surface oxygen is also below 38 ppm, so that excellent deep formability can be obtained. With respect to the coating materials of the samples N〇. 4 and 5 in which the 'Ar gas dew point is _35〇c or more, the surface oxygen amount is over 70Oppm or more, resulting in deterioration of surface ductility and fragmentation of the surface layer. Further, the sample No. 3 coated material which was annealed by a vacuum furnace was unavoidably elongated due to the time held at 800 ° C or higher, and the intermetallic compound layer was excessively grown, so that the deep transition property was deteriorated. 312XP/Inventive Manual (Supplement)/95.1 〇/95120301 17 1362683 [Table 1] Sample No. Diffusion Annealing Compound layer average thickness β 01 Surface oxygen amount ppm Forming result Remarks Ar gas dew point Its target temperature °匚800UC or more Sec 1 -45 1000 40 1.1 300 Good Invention Valley J 2 -45 1000 120 3.2 350 Good Invention Example 3 (Vacuum Furnace) 1000 1800 10 250 Fragmentation Comparative Example 4 -20 1000 120 3.0 1100 Fragmentation hb 5 -35 1050 180 9. 0 700 Fragmentation Comparative Example B - 45 800 20 0.2 280 Good Invention Example / -45 1100 120 6. 5 380 Good Invention Example [Simplified Drawing] FIG. 1 is a coating for a discharge electrode according to an embodiment of the present invention. A cross-sectional view of the important part of the material. Fig. 2 is a longitudinal sectional view showing a discharge electrode for a fluorescent discharge tube according to an embodiment of the present invention. Fig. 3 is a longitudinal sectional view showing a camping discharge and an important portion of a conventional discharge electrode for a fluorescent discharge tube. & [Major component symbol description] 1 Base 2 Surface 11、 53 Tube 12, 54 End plate 51 Glass tube 52 Discharge electrode 55 Support conductor 57 Wire 312XP/Invention manual (supplement)/95-1〇/95120301 18