200424028 玫、發明說明： 【發明所屬之技術領域】 本發明係關於例如使用於電子零件等之導電糊中適當 的鎳、銅、或銀等金屬微粉末及其製造方法、以及使用該 #之金屬微粉末之導電糊，特別是關於使用於在積層陶瓷 冷凝器的内部電極的情形下，燒結特性優異的金屬微粉末 等之製造技術。 【先前技術】 積層陶瓷冷凝器係以陶瓷的糊與金屬微粉末的糊藉由 積層之後加以燒結，陶瓷的介電體層與金屬微粉末的内部 電極層相互間所形成者。鎳、銅、銀等的導電性的金屬微 粉末作爲積層陶瓷冷凝器的内部電極用材料係爲有用，特 別是鎳微粉末在此等的用途係爲受到注目。 一般而言，積層陶瓷冷凝器係以如下而製造。即，鈦 酸鋇等的介電體陶瓷粉末與有機黏結劑混合的糊，製作形 成片狀的介電體綠片。另一方面，内部電極用的金屬微粉 末與有機溶劑、有機黏結劑等的有機化合物混合以形成金 屬微粉末糊，將其印刷至介電體綠片上、加以乾燥。該電 極層塗布介電體綠片在積層後、加熱壓著以形成積層體、 加工以形成目的之形狀。接者，爲除去有機黏結劑等的有 機成分，在弱酸性氣氛下於積層體中施予加熱處理（脫黏結 劑處理），之後在還原性氣氛中、1 3 00 °C前後、或其以上的 温度下燒成，最終的介電體陶瓷層的外側機外部電極烘 乾、以得到積層陶瓷冷凝器。 在如上述的積層陶瓷冷凝器之製造中，脫黏結劑處理 200424028 爲了處去有機化合物係在氧化氣氛中施行。因此，在脫黏 β 結劑處理中金屬微粉末係氧化而產生體積的膨張。再者， · 該脫黏結劑處理後，積層位在更高温下加熱而燒結，但是 由於該燒結係在還原氣氛中施行，而金屬微粉末還原使產 生體積的收縮。 因此，在積層陶瓷冷凝器之製造步驟中，由於氧化還 原反應使得金屬微粉末的膨張•收縮因而產生體積變化。 另一方面，介電體自身亦由於燒結而體積變化，但是使用 於内部電極之金屬微粉末的燒結起始温度係比介電體層的 _ 燒結起始温度要極端地低的情形時，由於内部電極層的急 劇收縮使得内部電極層與介電體層之間產生體積變化、被 稱爲缺陷之脫層係爲發生。該脫層由於導致冷凝器容量的 降低，燒結起始温度變高，因而企求不會引起急劇燒結之 金屬微粉末。 如上所述，使金屬微粉末的燒結起始温度高的方法， 例如：特開平1 1 - 808 1 7號公報中係已提案鎳粉中含有硫之 技術。 Ρ 然而，上述的特許文獻1中所記載的鎳粉之製造技術 」 中’燒結時硫係擴散至介電體層，而使得介電體層的電氣 的特性係爲劣化。 【發明內容】 因此，本發明如上述的鎳粉不含有硫時，提高金屬微 粉末的燒結起始温度可以抑制脫層的發生，以提供作爲目 的之金屬微粉末及其製造方法以及導電糊。 關於金屬微粉末的燒結起始温度、以下的事實係爲已 200424028 知。也就是說，金屬微粉末表面中存在氧化皮膜的時候， 燒結係無法開始，但是伴隨著燒成温度的上昇而氧化皮膜 還原、無法存在時，金屬微粉末的燒結係爲開始。例如， 根據鎳微粉末的情形，由於通常在200〜300 °C下開始燒 結，所以在200〜300 °C以上的温度下加熱則無法還原，爲 形成牢固的氧化皮膜可以抑止上述脫層的發生。 本發明人等基於上述事實，重覆專心一意硏究金屬微 粉末的氧化皮膜之結果，藉由臭氧氣體所生成的氧化皮 膜，與通常的氧化皮膜比較，由於開始還原的温度爲較高 之高温，該氧化膜係無法在金屬微粉末的表面上形成，金 屬微粉末的燒結起始温度可轉移至高温域，根據上述可抑 制脫層的發生而發現本發明。又，本發明人等，爲了具有 藉由臭氧氣體所生成的氧化皮膜之金屬微粉，燒結起始温 、度係轉移至比以前要高之高温域，減少燒結時金屬微粉末 的收縮率，由上述亦可抑制脫層的發生而發現本發明。 再者，本發明人等、藉由臭氧氣體之氧化處理爲了使 用一般的氧之氧化處理在更低之低温下實施、防止氧化處 理中的金屬微粉末彼此間的燒結所成之凝集，藉由抑制在 積層陶瓷冷凝器製造步驟之内部電極的短絡等的構造缺陷 的發生，係得到伴隨著積層陶瓷冷凝器的小型化、大容量 化的内部電極之薄層化、亦有助於低抵抗化而發現本發 明。本發明係爲基於上述知見者。 也就是說，本發明的金屬微粉末其特徵係在表面具有 藉由臭氧氣體所生成的氧化皮膜。 若根據本發明，藉由臭氧氣體所生成的氧化皮膜由於 200424028 形成於金屬微粉末的表面，由於從氧化被膜的還原所致的 喪失延遲，金屬微粉末的燒結起始温度係轉移至較高温 域，又基於燒結時金屬微粉末的收縮率係爲減少，在内部 電極層與介電體層之間發生可抑制脫層。又，若根據本發 明，藉由臭氧氣體於低温域下所成之氧化處理，藉由氧化 處理中的金屬微粉末彼此間的燒結以防止凝集、而抑制積 層陶瓷冷凝器製造步驟中内部電極的短絡等的構造缺陷的 發生。也就是說，本發明的金屬微粉末係混合有機溶劑、 與有機黏結劑等的有機化合物以形成金屬微粉末糊，作爲 積層陶瓷冷凝器的内部電極使用之情形時，爲了使燒結起 始温度爲高温、與介電體的燒結起始温度差異不大，使收 縮率降低且介電體之間的體積變化降低，又凝集粒子少， 使得製造步驟中可抑制脫層、裂縫、内部電極的短絡、等 的構造缺陷的發生。因此，根據本發明的金屬微粉末，可 實現伴隨著積層陶瓷冷凝器的小型化、大容量化之内部電 極的薄層化、低抵抗化。 在此等的金屬微粉末中，氧化皮膜的厚度爲1〜10nm 係爲所企求。氧化被膜的厚度低於lnm之情形時，由於氧化 被膜的還原之喪失延遲無法充分地達成，因此金屬微粉末 的燒結起始温度無法轉移至較高之高温域，結果係不能抑 制上述脫層的發生。又，氧化被膜的厚度超過10nm之情形 時，由於金屬微粉末的燒結性降低而係爲不佳。爲了使此 等的脫層發生防止與燒結性的防止兩者能更有實効，上述 氧化皮膜的厚度以2〜lOnm爲佳、2〜5 nm爲更佳。 又，在上述金屬微粉末中，金屬微粉末爲本發明的金 200424028 屬微粉末可舉例如鎳。銅、銀等的導電糊塡料爲適當的金 屬微粉末、或又鋁、鈦、鉻、錳、鐵、鈷、鉍等的金屬微 粉末及該等之合金微粉末等。作爲積層陶瓷冷凝器的内部 電極用使用之情形時，優異的導電性、可於還原氣氛下燒 成、便宜之鎳微粉末係爲最適當。 在此等的金屬微粉末中，合適的金屬微粉末之平均粒 徑爲1 μ m以下係爲所企求。上述平均粒徑超過1 # m之情形 時，燒結性的降低、或積層陶瓷冷凝器的内部電極彼此間 的短絡等的構造缺陷容易產生而係爲不佳。爲了防止該燒 結性的降低或構造缺陷的發生時，金屬微粉末的平均粒徑 爲0·5 μιη以下係爲企求。然而，上述平均粒徑爲過度小之情 形時，由本發明的氧化步驟中進行金屬微粉末彼此間的燒 結、凝集，上述平均粒徑之下限値爲0.1 μιη係爲所企求。 再者，在此等的金屬微粉末中，金屬微粉末的氧濃度 與氧化皮膜厚度的比（氧濃度/氧化皮膜厚度）爲0.3〜1.0係 爲所企求。 該等之氧濃度係意味含有氧化被膜之金屬微粉末的氧 濃度，氧化被膜的厚度係意味含有氧化被膜之金屬微粉末 的形狀作爲假想球之情形時，從該中心向徑方向所測定的 氧化被膜的厚度。 上述比低於0.3之情形時，爲了使氧化被膜容易還原’ 氧化被膜之上述喪失的延遲係無法充分地達成，因此金屬 微粉末的燒結起始温度無法轉移至較高之高溫域’其結果 無法上抑制述脫層的發生。又，上述比超過1 ·〇之情形時’ 由於金屬微粉末的燒結性降低而係爲不佳。爲了使此等的 200424028 脫層發生防止與燒結性的防止兩者能更有實効，上述比爲 0.3〜0.8爲佳、以0.3〜0·5ηιη爲更佳。 又本發明的金屬微粉末之製造方法，其特徵爲有利地 製造上述的金屬微粉末之方法，金屬微粉末在碳酸水溶液 中處理、接者於臭氧氣體氣氛中施予氧化處理、在表面形 成氧化皮膜。 根據本發明的金屬微粉末之製造方法，藉由臭氧氣體 所生成的氧化皮膜形成至金屬微粉末的表面，由於氧化被 膜的還原所致的喪失延遲、使金屬微粉末的燒結起始温度 於較高之高温域轉移、再者基於燒結時金屬微粉末的收縮 率減少，於内部電極層與介電體層之間發生可抑制脫層。 又，若根據本發明，藉由臭氧氣體於低温域下所成之氧化 處理、防止由氧化處理中的金屬微粉末彼此間的燒結所成 之凝集，藉由抑制積層陶瓷冷凝器製造步驟中内部電極的 短絡等的構造缺陷的發生，可實現伴隨著積層陶瓷冷凝器 的小型化、大容量化之内部電極的薄層化、低抵抗化。 在此等的金屬微粉末之製造方法中，氧化處理在200 〜25 0°C的温度範圍下進行係爲所企求。上述氧化處理在低 於200 °C的温度下進行時，由於金屬微粉末的燒結起始温度 需要在高温，因此形成氧化皮膜時需要長時間的氧化處 理，係爲不實用。又，在超過25 0 °C之温度下進行時，施以 氧化處理直至到達金屬微粉末的内部，會產生燒結性的降 低、或積層陶瓷冷凝器的内部電極的抵抗値的上昇等而爲 不佳。爲了防止氧化被膜的形成時間進一步縮短、且燒結 性的降低時，係企求氧化處理以220〜230 °C的温度範圍下 -10- 200424028 進行。 又，在上述金屬微粉末之製造方法中，氧化處理係於1 〜2 0體積％的臭氧濃度範圍進行係爲所企求。氧化處理低 於1體積％之臭氧濃度下進行時，燒結起始温度係轉移至高 温域，爲了得到牢固的氧化皮膜，需要長時間的氧化處理， 而爲不實用。又，氧化處理超過20體積％之臭氧濃度下進 行時，直至金屬微粉末的内部快速氧化時，不僅容易引起 燒結性的降低、且結果成本或價錢變成比較貴而爲不實用。 又，在上述金屬微粉末之製造方法中，碳酸水溶液中 的處理係於ρΗ5·5〜6.5的範圍中進行係爲所企求。碳酸水 溶液中的處理在低於ρΗ5.5下進行時，金屬微粉末表面係生 成不均勻的氧化皮膜而降低金屬微粉末的燒結性。又，金 屬微粉末本身溶解停止則產生表面的龜裂。超過ρΗ6· 5下進 行時，無法去除在金屬微粉末表面附著、或吸著的氫氧化 物，乾燥後残存的氫氧化物變成不均勻的氧化皮膜。爲了 進一步防止此等的缺點，碳酸水溶液中的處理係企求 ρ Η : 5 · 5〜6 · 0的範圍下進行。 再者’在此等的金屬微粉末之製造方法中，金屬微粉 末特別是鎳，由於成本價錢比較不貴的關係而爲實用，使 用依照上述之製造方法所製造的金屬微粉末，在使用於電 子零件等時’可防止上.述脫層的發生而得到導電糊。 以下’在本發明適當的實施形態方面，係參照圖面進 一步*詳細說明鎳微粉末之製造例。而且，根據本發明金屬 微粉末之製造方法製造的金屬微粉末，除了鎳以外，適用 於可舉例如銅或銀的糊塡料、鈦材的複合材、或觸媒等的 -11· 200424028 各種用途之金屬微粉末，亦可用於再者鋁、鈦、鉻、錳、 鐵、鈷、鈾、鉍等的金屬微粉末之製造。本發明的金屬微 粉末可藉由氣相法或液相法等公知方法加以製造，特別是 藉由將金屬物氯化物氣體與還原性氣體接觸以生成金屬微 粉末之氣相還原法、或將熱分解性的金屬化合物噴霧、熱 分解之噴霧熱分解法、所生成的金屬微粉末的粒子徑可以 容易地控制，以及從球狀的粒子可更有効率地製造之觀點 而言爲佳之方法。 在鎳微粉末氣相還原法中，亦可將氣化的氯化鎳之氣 體與氫等的還原性氣體反應、使固體的氯化鎳加熱、蒸發， 而生成氯化鎳氣體。然而，考慮氯化鎳的氧化或吸濕防止 又能量効率時，氯氣係接觸至金屬鎳而使氯化鎳氣體連續 的發生，該氯化鎳氣體於還原步驟直接供給，接者與還原 性氣體接觸的氯化鎳氣體係連續的還原，而製造鎳微粉末 之方法係爲有利。 根據氣相還原反應之鎳微粉末之製造過程中，氯化鎳 氣體與還原性氣體接觸的瞬間生成鎳原子，鎳原子彼此之 間係由於衝突·凝集使超微粒子生成、成長。因此，還原 步驟係根據氯化鎳氣體的分壓或温度等的條件，而決定生 成的鎳微粉末之粒徑。根據上述鎳微粉末之製造方法，基 於所需氯氣的供給量之量產生的氯化鎳氣體，控制氯氣的 供給量而調整供給至還原步驟之氯化鎳氣體的量時，如上 所生成的鎳微粉末之粒徑可加以控制。再者，金屬氯化物 氣體從氯氣與金屬發生的反應，與藉由固體金屬氯化物的 加熱蒸發而產生金屬氯化物氣體之方法有所不同，不能減 -12- 200424028 少載氣的使用，根據製造條件亦不可使用。因此，氣相還 原反應由於載氣的使用量降低時係伴隨者加熱能量的減 少，製造成本的降低可爲商量。 又，藉由將惰性氣體混合至氯化步驟所發生的氯化鎳 氣體中，可加以控制還原步驟中氯化鎳氣體的分壓。因此， 藉由控制供給至氯氣的供給量或還原步驟的氯化鎳氣體的 分壓，可以控制鎳粉末的粒徑，因而可安定鎳微粉末的粒 徑，且同時可任意地設定粒徑。 藉由如上述的氣相還原法之鎳微粉末的製造條件，可 任意地設定平均粒徑1 // m爲以下，例如出發原料之金屬鎳 粒徑爲約5〜20mm的粒狀、塊狀、板狀等爲佳，又，該純度 係槪略爲99.5%以上爲佳。該金屬鎳首先氯氣與反應以生 成氯化鎳氣體，此時的温度爲了使反應充分地進行係爲800 °C以上，且鎳的熔點爲1453 °C以下。當考慮反應速度與氯 化爐的耐久性時，實用上係以900 °C〜1100 °C的範圍爲佳。 接者，該氣化錬氣體於遠原步驟直接供給、與氨氣體 等的還原性氣體作接觸反應，氮或氬等的惰性氣體、相對 於氯化鎳氣體、係混合1〜30莫耳％，該混合氣體於還原步 驟中導入爲佳。又，氯化鎳氣體與全部或獨立地氯氣亦可 於還原步驟供給。如該氯氣由於係在還原步驟加以供給， 所以可調整氯化鎳氣體的分壓，而變成可控制生成的鎳粉 末粒徑。若還原反應的温度爲反應完成足夠的温度以上， 生成固體狀鎳粉末方面’因爲處理容易以鎳的熔點以下爲 佳，若考慮經濟性時以9 0 0 °C〜1 1 〇 〇 °C爲實用的。 進行此等還原反應生成鎳微粉末的話，才接者冷卻生 -13- 200424028 成鎳粉末。冷却的時候，藉由所生成的鎳之一次粒子彼此 間的凝集可防止二次粒子的生成，以得到所望粒徑之鎳粉 末，終止還原反應之1 000 °c左右的氣體流藉由吹入氮氣體 等的惰性氣體直至400〜800 °c左右，而急速冷却係爲所企 求。之後，所生成的鎳粉末藉由例如袋濾器等而分離、回 收。 又，藉由噴霧熱分解法的金屬微粉末之製造方法中， 作爲熱分解性金屬化合物之原料，具體而言可使用金屬的 硝酸鹽、硫酸鹽、羥基硝酸鹽、羥基硫酸鹽、氯化物、銨 錯化物、磷酸鹽、羧酸鹽、烷氧基化合物等的1種或2種以 上。噴霧含有該鎳化合物之含油溶液，以形成微細的液滴， 此時的溶劑可使用水、醇、丙酮、醚等。又，噴霧的方法 可藉由超音波或雙噴射嘴等的噴霧方法而進行。作爲此等 微細的液滴係於高温下加熱、以熱分解金屬化合物，而生 成金屬微粉末。此時的加熱温度係使用的特定金屬化合物 爲熱分解之温度以上，較佳爲金屬的熔點左右。 藉由液相法的金屬微粉末之製造方法中，例如鎳微粉 末之製造中，將含有硫酸鎳、氯化鎳或鎳錯化物之鎳水溶 液添加至氫氧化鈉等的鹼金屬氫氧化物中等接觸、而生成 鎳氫氧化物，接者在胼等的還原劑中還原鎳氫氧化物以得 到金屬鎳粉末。此等所生成的金屬鎳粉末爲了得到均勻的 粒子可視需要的解碎處理。 以下係例舉於金屬鎳中接觸氯氣以連續地產生氯化鎳 氣體，該氯化鎳氣體與還原性氣體接觸、還原，而製造鎳 微粉末之方法，而更詳細地説明。 -14- 200424028 A.氯化步驟 第1圖係爲使用於本發明中以製造金屬微粉末的裝 置。氯化步驟在如同圖所示之氯化爐1 0進行爲佳。在氯化 爐10的上端面中設置爲了供給原料金屬鎳（M)之供給管 1 1。又，氯化爐1 0的一上側部係接續氯氣供給管1 2，該下 側部係接續惰性氣體供給管1 3。在氯化爐1 〇的周圍配置加 熱裝置14，在氯化爐10的其他上側部係接續移送管兼噴嘴 15。氯化爐10不管是縱型、横型，但是爲了使固體一氣體 接觸反應能均勻地進行以縱型爲佳。將氯氣流量計測且連 續地從氯氣供給管12導入。將移送管兼噴嘴15接續後述的 還原爐20上端面，以氯化爐10發生的氯化鎳氣體等具有對 還原爐20移送之功能。又，移送管兼噴嘴15的下端部係有 突出還原爐20内作爲氯化鎳噴出噴嘴的功能。不管出發原 料之金屬鎳（M)的形態，從接觸効率、壓力損失上昇防止的 観點而言，以粒徑約5mm〜20mm的粒狀、粗狀、板狀等爲 佳、又該純度以槪略爲99.5%以上爲佳。氯化爐10内金屬 鎳（M)的塡充層高以氯氣供給速度、氯化爐內温度、連續運 転時間、金屬鎳（M)的形狀等爲基礎，供給氯氣係改變氯化 鎳氣體設置於適當足夠的範圍爲佳。氯化爐1 〇内的温度爲 充分進行反應爲800°C以上、鎳的熔點爲1483°C以下。考慮 反應速度及氯化爐10的耐久性時，實用上以900 °C〜1100 °C 的範圍爲佳。 在本發明的金屬微粉末之製造方法中，對塡充金屬鎳 (M)之氯化爐10連續供給氯氣，係帶來氯化鎳氣體的連續發 生。所以，基於氯氣供給量支配氯化鎳氣體的發生量，支 -15- 200424028 配後述的還原反應，該結果可生產作爲目的之製品鎳微粉 末。 再者，關於氯氣供給係以以下的還原步驟作具體的説 明。 因氯化步驟發生的氯化鎳氣體，將其藉由移送管兼噴 嘴15移送至還原爐20，根據場所從惰性氣體供給管13之氮 或氬等的惰性氣體，相對於氯化鎳氣體係混合lmol %〜 30mol%，且將該混合氣體移送至還原爐20。通過移送管兼 噴嘴15之混合氣體中較佳的氯化鎳氣體分壓，於全壓1.0時 爲0.5〜1.0的範圍，特別是製造粒徑爲0·2μιη〜0.5μιη之小 粒徑的鎳微粉末之情形時，以分壓0.6〜0.9左右爲佳。 Β .還原步驟 因氯化步驟發生的氯化鎳氣體係連續地移送至還原爐 20。還原步驟係企求使用以如第1圖所示之還原爐20。同圖 所示之還原爐20係形成圓筒狀，以該上半部進行還原、而 該下半部進行冷却。在還原爐20的上端部中，係於上述的 移送管兼噴嘴15的噴嘴（以下簡稱爲噴嘴15)下方突出。 又，在還原爐20的上端面係接續還原性氣體供給管（氫氣體 供給管）21。又，還原爐20的周圍係配置加熱裝置22。噴嘴 15係從氯化爐10對還原爐20内氯化鎳氣體（包含惰性氣體 情形），較佳係流速具有噴出之功能。 根據氯化鎳氣體與氫氣體之還原反應進行時，從噴嘴 15的先端部，形成像LPG等氣體燃料的燃燒火焰延伸至下 方的光焰F。對還原爐20的氫氣體供給量根據氯化鎳氣體的 化學當量、換言之，爲供給氯化爐10之氯氣化學當量的1.0 -16- 200424028 〜3 · 0倍左右，較佳爲1 · 1〜2.5倍左右，其並沒有特別地限 制。又，還原反應的温度亦可爲反應完成時足夠的温度以 上，因爲生成固體狀的鎳微粉末方面係爲容易處理，所以 以鎳的熔點以下爲佳。又，上述温度考慮反應速度、還原 爐2 0的耐久性、經濟性時以9 0 0 °C〜1 1 〇 〇 °C係爲實用，其沒 有特別地限制。 根據上述，氯化爐10中所導入的氯氣係實質上爲同莫 耳量的氯化鎳氣體且將其作爲還原原料。根據從噴嘴1 5所 噴出的氯化鎳氣體或氯化鎳與惰性氣體的混合氣體而調整 氣體流的線速度，可將所得鎳微粉末P的粒徑適當化。換言 之，噴嘴徑若爲一定的話，藉由調整對氯化步驟的氯供給 量與惰性氣體供給量，可將由還原爐2 0生成的鎳微粉末P 的粒徑調整至目的的範圍內。 關於噴嘴1 5先端中較佳的氣體流之線速度（氯化鎳氣 體及惰性氣體的合計（以還原温度之氣體供給量所換算的 計算値）），在900°C〜1 l〇〇°C的還原温度中係設定爲約lm/ 秒〜30m/秒。以氫氣體之還原爐20内的軸方向之線速度， 以氯化鎳氣體之噴出速度（線速度）的1/50〜1/3 00程度爲 佳、1/80〜1/2 5 0爲更佳。因此，實質上於静的氫氣氛中的 氯化鎳氣體係由噴嘴15中噴射出來。 而且，還原性氣體供給管2 1的出口方向係以不面向光 焰F側爲佳。又，生成鎳微粉末時所使用的還原性氣體’可 使用以上所示的氫氣體以外的硫化氫氣體等，若考慮對所 生成的鎳微粉末的影響時，以氫氣體爲適當。再者’製造 鎳微粉末的情形時，金屬氯化物氣體與還原性氣體接觸、 •17- 200424028 反應之還原反應温度領域通常爲900〜1 20 0°C、但是以950 〜1100 °C爲佳、更佳爲980〜1050 °C。 C ·冷却步驟 還原步驟所生成的鎳微粉末係如第1圖所示，在與還原 爐20内的噴嘴15反對側的空間部分（下方部分）中冷却。進 行冷却的較佳實例，其實施形態係由光焰F先端下方的空間 部分藉由冷却氣體供給管23吹入冷却用惰性氣體而構成。 而且，本發明所謂的冷却，係在還原反應所生成的氣體流 (包含鹽酸氣體）中爲了抑制或停止鎳粒子的成長所進行的 操作，具體而言，意味終止還原反應之1000 °C左右的氣體 流急速冷卻至400 °C〜800 °C左右之操作。不用說亦可進行 冷卻至其以下的温度。 爲了冷卻所生成的鎳微粉末之惰性氣體，若沒有影響 所生成的鎳微粉末的話，並沒有特別地限制，可使用氮氣 體、氬氣體等。其中以氮氣體便宜而爲適當。再者，冷却 用惰性氣體的供給量，通常生成的每1克鎳微粉末爲5N1/分 以上、較佳爲10〜50N1/分。而且，所供給的惰性氣體之温 度，通常爲〇〜1〇〇 °C、但是在0〜80 °C的情形時有更好的効 果。 D.回收步驟 氯化、還原及冷却的各步驟係順次地經過的鎳微粉末P 與鹽酸氣體及惰性氣體的混合氣體，經過第1圖的噴嘴24， 移送至回收爐（沒有圖示），將其由混合氣體分離回收鎳微 粉末P。在分離回收中，以例如袋濾器、水中吸收分離裝置、 油中吸收分離裝置及磁氣分離裝置的1種或2種以上之組合 -18- 200424028 爲適當，但是並沒有特別地限制。 又’在分離回收前或後，視需要所生成的鎳微粉末亦 可以水、碳原子數1〜4的1價醇等的溶劑加以洗浄。再者、 視需要的所生成的鎳微粉末係在用氫氣體或惰性氣體稀釋 的氫氣體之還原性氣氛下進行氫還原處理，亦可稍微調整 鎳微粉末中的氧含有量。氫還原處理温度爲220〜300。(：爲 佳、250〜300 °C爲更佳。氫還原處理時間爲5〜60分鐘。 E ·氧化處理步驟 本發明中的鎳微粉末係以如上述的方法所得到的鎳微 粉末在碳酸水溶液中處理、接者在臭氧氣氛中加熱且氧化 處理。 碳酸水溶液處理係在金屬鎳微粉末漿料中藉由吹入碳 酸氣體以調整pH 5.5〜6.5，碳酸水溶液於常温下進行60分 鐘的處理。 氧化處理係藉由氣相還原法而得到，施加碳酸水溶液 處理後乾燥的鎳微粉末，置入氧化爐内加熱，藉由在該氧 化爐内供給臭氧氣體而實施。臭氧氣體可與氧、空氣、一 氧化碳、二氧化碳等的氣體、或水蒸氣、低級醇等混合而 供給’與氧氣混合係更有効果。臭氧氣體濃度爲1〜20體積 %的範圍爲適當、更佳爲5〜20體積％。氧化處理温度係以 2 0 0〜2 5 0 °C的低温度領域爲適當，較佳爲2 2 0〜2 3 0 °C的範 圍。氧化處理時間係按照前述臭氧氣體濃度與氧化處理温 度’像氧化皮膜的厚度爲1〜10nm的話係於1分〜30分鐘的 範圍内作適宜地選擇爲佳。 氣相還原法所得之鎳微粉末，藉由於大氣中放置設 *19- 200424028 立，吸收水分而生成氫氧化鎳。此等的鎳微粉末與有機溶 劑等混合作爲鎳糊的情形中，結果分散性降低、鎳微粉末 彼此之間凝集且粗粉増加，使得除去氫氧化鎳的熱處理需 要花費長時間。因此，對於藉由氣相還原法所得之鎳微粉 末施加氧化處理情形，產生越快速進行上述的氧化處理越 佳。 氧化處理後於視需要的氫氣氛、或惰性氣體稀釋的氫 氣體氣氛中進行氫還原處理，亦可稍微調整鎳微粉末中的 氧含有量。 E.導電糊的製作 如上述所得之金屬微粉末以導電糊或電極形成用糊爲 適當。此等的金屬微粉末係與有機溶劑及黏結劑捏合以形 成糊。有機溶劑（有機展色料）若使用從前的導體糊者的話 已足夠，可使用例如、乙基纖維素、乙二醇、甲苯、二甲 苯、礦物油、丁基卡必醇、萜品醇等的高沸點有機溶劑。 黏結劑係使用有機或無機黏結劑，使用乙基纖維素等的高 分子黏結劑爲佳。 又，視需要的鉛系玻璃、鋅系玻璃或矽酸系玻璃等的 玻璃料或氧化錳、氧化鎂、氧化鉍等的金屬氧化物塡料等， 亦可於形成.糊時加以混合。藉由混合該等之添加物塗布至 陶瓷等的基材上，燒結形成電極時，可形成與基材的密著 性優異的高傳導性電極，又提昇與焊料的濕潤性。此外， 可在糊中添加苯二酸酯或硬脂酸等的可塑劑、或分散劑等。 如上所述’在金屬微粉末的表面上藉由臭氧氣體形成 牢固的氧化皮膜，可得到燒結起始温度高、燒結時的收縮 -20- 200424028 率低、由金屬微粉末彼此間的凝集粗粉變少、又與有機溶 劑等混合所形成的金屬糊時分散性優異、具有作爲積層陶 瓷冷凝器的内部電極用之適合的功能之金屬微粉末。藉由 使用此等的金屬微粉末，可控制積層陶瓷冷凝器製造步驟 中脫層等的構造缺陷。 【實施方式】 實施例 以下，係根據本發明的實施例明確說明本發明的効果。 鎳粉的燒結起始温度評價 [實施例1] 在第1圖中所示之金屬鎳微粉末製造裝置的氯化爐10 内，出發原料之平均粒徑5mm的金屬鎳微粉末由原料供給 管1 1加以塡充，且由加熱裝置1 4之爐內氣氛温度係變成 1 l〇G°C。接者，由氯氣供給管12之氯氣係供給至氯化爐10 内，使金屬鎳氯化而產生氯化鎳氣體。在該氯化鎳氣體中， 由設置於氯化爐10的下側部之惰性氣體導入管13，使供給 氯氣供給量10% (莫耳比）的氮氣體混合。因此，將氯化鎳 氣體與氮氣體的混合氣體透過噴嘴15導入還原爐20。 接者，還原步驟係將氯化鎳氣體與氮氣體的混合氣 體’在藉由加熱裝置22施予1 000 °C之爐內氣氛温度的還原 爐20中，由噴嘴15以流速2.3m/秒（換算1000°C)導入。同時 來自設置於還原爐20内的上端部還原性氣體導入管41之氫 氣體，係以流速7N1/分供給至還原爐20内以還原氯化鎳氣 體’而得到鎳微粉末P。 再者，冷却步驟係將還原步驟中所生成的鎳微粉末P， -21- 200424028 接觸由設置於還原爐20下側部之冷却氣體供； 1 6.4N1/分·克所供、給之氮氣體，冷卻鎳微粉末P 所生成的鎳微粉末P與氯氣及鹽酸蒸氣一起透過 入並未圖示之回收爐中。 由此等噴嘴24之回收爐所導入之氮氣體、鹽 及鎳微粉末P，係導入並未圖示之袋濾器中分離回 末。因此，將回收的鎳微粉末P以熱水洗浄，且在 漿料中吹入碳酸氣體以調整PH5.5,在常温下鎳微 碳酸水溶液中出裡60分鐘。 將碳酸水溶液處理之鎳微粉末乾燥之後進 理。以氣相還原法所得之鎳微粉末P裝入氧化爐、 置中爐内氣氛温度變成200 °C、來自氧化氣體供給 氣體含有5體積％臭氧一氧混合氣體係於10分鐘導 化處理鎳微粉末P，以得到製品鎳微粉末。 [實施例2] 當與實施例1同樣製造之鎳微粉末p以氧化 時，氧化爐內氣氛温度爲250C、臭氧一氧混合氧 的臭氧濃度爲5體積％、氧化處理時間30分鐘、以 處理。 [比較例1 ] 製造與實施例1同樣地鎳微粉末P，對未實施 液處理施加氧化處理。當氧化處理時作爲氧化氣 氣。又，氧化處理温度、氧化處理時間係與實施f 件下進行。 [比較例2] 給管23以 。因此， 噴嘴24導 酸蒸氣、 收鎳微粉 鎳微粉末 粉末係於 行氧化處 將加熱裝 管之臭氧 入、且氧 步驟氧化 化氣體中 實施氧化 碳酸水溶 體係爲氧 河1相同條 -22- 200424028 製造與實施例1同樣地鎳微粉末p，對未實施碳酸水溶 液處理施加氧化處理。當氧化處理時作爲氧化氣體係爲氧 氣。再者，爲了具有與實施例1所得之鎳微粉末相同厚度的 氧化皮膜與氧濃度’係於氧化處理温度爲400 °C、氧化處理 時間30分鐘下實施。 就上述實施例1、2及比較例1、2而言，其金屬鎳微粉 末的氧化皮膜厚度、氧濃度、燒結起始温度、收縮率及粒 度分布係藉由下述的方法加以測定。 1) 氧化皮膜厚度 首先’金屬鎳微粉末係在延伸膠棉膜之銅製片網孔上 直接振動，之後蒸鍍碳以製作測定試料。接者，使用200kV 電解放射型穿透電子顕微鏡（HF-2000、日立製作所製）觀察 測定試料的格子像，且測定金屬鎳微粉末表面的氧化皮膜 厚度。 2) 氧濃度 將金屬鎳微粉末塡充至鎳製的膠囊內，將其裝入黒鉛 坩鍋、在氬氣氛下加熱至500 °C，將此時發生的一氧化碳用 IR加以定量，以求得金屬鎳微粉末中的氧濃度。 3) 燒結起始温度 混合1克的金屬鎳微粉末，3重量％的樟腦、3重量％的 丙酮，塡充至内徑5mm、高度10mm的圓柱狀金屬中，處理 面壓1噸的荷重以製作試験樣品。該試験樣品的燒結起始温 度之測定係使用熱膨張收縮舉動測定裝置（TMA-8310、麗 卡庫股份有限公司社製），於弱還原性氣氛（1.5%氫- 98.5% 氮混合氣體）氣氛的下、以昇温速度5°C /分的條件進行。上 -23- 200424028 述測定所得之收縮率曲線中，以l %收縮的時點之温度作爲 燒結起始温度。 4) 收縮率 再用上述3)的燒結起始温度測定所得之收縮率曲線 中，以升溫至500 °C時點的重量減少率作爲收縮率。 5) 粒度分布 使用黏度測定器LS 23 0(可錄塔社製），將試料懸浮至環 醯醇（異丙醇10%、乙醇90%)且以勻化器經3分鐘分散後測 定，求得積算粒度分布中積算値爲5 0體積％所成之粒子徑 (D50)。 第1表係表示實施例1、2及比較例1、2所得之鎳微粉末 的氧化皮膜厚度、氧濃度、燒結起始温度、收縮率及粒度 分布之測定結果。 第1表 氧化條件 _ 測定結果 氧化氣體 氧化温度 (°C) 氧化時間 汾） 氧化皮膜厚 度（nm) 氧濃度 氧化皮膜 密度*) 燒結開始 温度(°C) 收縮率 (%) 粒度 分布 實施例1 5體積％臭氧 200 10 5 1.65 0.33 380 6.0 0.86 實施例2 5體積％臭氧 250 30 9 6.21 0.69 450 4.3 1.12 比較例1 氧 200 10 1 0.22 0.22 220 8.2 1.55 比較例2 氧 400 30 5 1.20 0.24 330 6.5 2.05 *)氧化皮膜密度：氧濃度與氧化皮膜厚度的比（氧濃度/ 氧化皮膜厚度） 由第1表可明顯地知道，實施例1、2中所得之鎳微粉 末，對比於比較例1、2中所得之鎳微粉末，其氧化皮膜厚 -24- 200424028 度係略大’氧含有量亦多者，且亦爲燒結起始温度高、收 _ $ /j、者°換言之’各實施例中鎳微粉末對比於各比較例 之鎳微粉末’係判斷因牢固地改善燒結舉動而得到足夠的 氧化皮膜。而且，所得的鎳微粉末之粒度分布（粗大粒子的 比例）方面’各實施例係得到比各比較例小的數値。特別是 比較例2中關於粒度分布之値大，所以可在高温下長時間的 氧化處理。 鎳糊的分散性評價 [實施例3] 實施例1所得、經臭氧氣體氧化處理的50質量％鎳微粉 末、與5質量％乙基纖維素與95質量％萜品醇所成之5〇質量 %展色料’以3輥機捏合以製作糊，將其塗布以測定膜密度。 [比較例3 ] 將比較例2所得之鎳微粉末經氧氣氧化處理、使用具有 與實施例1所得之鎳微粉末相同厚度的氧化皮膜之相同氧 濃度的鎳微粉末，與實施例3同樣地製作糊，將其塗布以測 定膜密度。 第2表係表示實施例3及比較.例3所得之糊的膜密度測 定結果。 第2表 膜密度 實施例3 5 · 0 克 / c m3 比較例3 3，5 克 /cm3 若根據第2表的話，實施例3的糊係比比較例3的糊膜密 度大，而可判斷分散性良好。因此、實施例3的糊作爲積層 -25- 200424028 陶瓷冷凝器的内部電極使用時，可得到裂縫、脫層等的構 造缺陷之抑制効果。 如以上説明，根據本發明的金屬微粉末之製造技術， 金屬微粉末的表面係藉由臭氧氣體形成氧化皮膜，由於氧 化被膜的還原所致的喪失延遲金屬微粉末的燒結起始温度 係轉移至較高的高温域，再者燒結時基於金屬微粉末的收 縮率減少，可抑制内部電極層與介電體層之間發生的脫 層。所以，本發明在電子零件等使用的導電糊以製造合適 的金屬微粉末係爲有望。 【圖式簡單說明】 第1圖係表示使用於本發明中製造金屬微粉末的裝置 之圖。 元件符號説明表 10…氯化爐 11…原料金屬鎳（M)供給管 12…氯氣供給管 1 3…惰性氣體供給管 1 4…加熱裝置 15…移送管兼噴嘴 2〇…還原爐 21…還原性氣體供給管 22···力口熱裝置 23…冷却氣體供給管 24…噴嘴 Μ…原料金屬鎳 -26- 200424028 F…光焰200424028 Description of the invention: [Technical field to which the invention belongs] The present invention relates to, for example, appropriate nickel, copper, or silver metal powders suitable for use in conductive pastes such as electronic parts, a method for manufacturing the same, and metals using the # Micropowder conductive paste, in particular, relates to a manufacturing technique of metal fine powder and the like having excellent sintering characteristics in the case of an internal electrode of a laminated ceramic condenser. [Prior art] Multilayer ceramic condensers are formed by laminating ceramic paste and metal powder powder, and then sintering the ceramic dielectric layer and the metal electrode powder. Conductive metal fine powders such as nickel, copper, and silver are useful as materials for internal electrodes of laminated ceramic condensers. In particular, nickel fine powders have attracted attention in these applications. Generally, a multilayer ceramic condenser is manufactured as follows. That is, a paste of a dielectric ceramic powder such as barium titanate and an organic binder is mixed to form a green dielectric sheet. On the other hand, metal fine powder for internal electrodes is mixed with organic compounds such as organic solvents and organic binders to form a metal fine powder paste, which is printed on a green dielectric sheet and dried. This electrode layer-coated dielectric green sheet is laminated after heating and pressing to form a laminated body, and processed to form a desired shape. Then, in order to remove organic components such as organic binders, a heat treatment (debinder treatment) is performed in the laminate in a weakly acidic atmosphere, and then in a reducing atmosphere, around 1 300 ° C, or more It is fired at a temperature of 50 ° C, and the outer electrodes of the outer layer of the final dielectric ceramic layer are dried to obtain a laminated ceramic condenser. In the manufacture of laminated ceramic condensers as described above, the debonding agent treatment 200424028 is performed in an oxidizing atmosphere in order to remove organic compounds. Therefore, the metal fine powder is oxidized during the de-binding β-caking treatment to cause volume expansion. Furthermore, after the debonding agent is processed, the laminate is heated and sintered at a higher temperature, but the sintering is performed in a reducing atmosphere, and the reduction of the metal fine powder causes a volume shrinkage. Therefore, in the manufacturing step of the multilayer ceramic condenser, the metal fine powder expands and contracts due to the oxidation-reduction reaction, resulting in a volume change. On the other hand, the dielectric body itself changes volume due to sintering, but the sintering start temperature of the metal fine powder used for the internal electrode is extremely lower than the _ sintering start temperature of the dielectric layer. The abrupt shrinkage of the electrode layer causes a volume change between the internal electrode layer and the dielectric layer, and delamination called defects occurs. This delamination causes a reduction in the condenser capacity and a high sintering start temperature, so that metal fine powders that do not cause rapid sintering are sought. As described above, a method for increasing the sintering start temperature of the fine metal powder is, for example, Japanese Patent Application Laid-Open Nos. 1 1 to 808 1 7 which has proposed a technique for containing sulfur in nickel powder. P However, in the "manufacturing technology of nickel powder described in Patent Document 1", the sulfur system diffuses to the dielectric layer during sintering, and the electrical characteristics of the dielectric layer are deteriorated. [Summary of the Invention] Therefore, when the nickel powder of the present invention does not contain sulfur, increasing the sintering start temperature of the metal fine powder can suppress the occurrence of delamination, so as to provide the metal fine powder as a purpose, a method for manufacturing the same, and a conductive paste. The following facts about the sintering start temperature of the fine metal powder are known as 200424028. In other words, when an oxide film is present on the surface of the metal fine powder, the sintering system cannot be started, but when the oxide film is reduced due to the increase in the firing temperature and cannot exist, the sintering system of the metal fine powder is started. For example, according to the situation of nickel fine powder, since sintering usually starts at 200 ~ 300 ° C, it cannot be reduced by heating at a temperature above 200 ~ 300 ° C. In order to form a strong oxide film, the above-mentioned delamination can be suppressed. . Based on the above facts, the inventors repeated the results of intensive investigation of the oxide film of the metal fine powder. The oxide film generated by the ozone gas has a higher temperature than the ordinary oxide film because of the higher temperature at which the reduction begins. The oxide film cannot be formed on the surface of the metal fine powder, the sintering starting temperature of the metal fine powder can be transferred to a high temperature region, and the present invention was found based on the above-mentioned fact that the occurrence of delamination can be suppressed. In addition, the inventors of the present invention transferred the sintering temperature and degree to a higher temperature range than before to reduce the shrinkage of the fine metal powder during sintering in order to obtain fine metal powder with an oxide film generated by ozone gas. The present invention has been found to suppress the occurrence of delamination. In addition, the inventors and others carried out the oxidation treatment with ozone gas at a lower temperature in order to use a general oxygen oxidation treatment to prevent aggregation of sintered metal fine powders during the oxidation treatment. It suppresses the occurrence of structural defects such as short-circuiting of the internal electrodes in the manufacturing steps of the multilayer ceramic condenser, and reduces the thickness of the internal electrodes accompanying the miniaturization and large capacity of the multilayer ceramic condenser. It also contributes to low resistance. Instead, the present invention was discovered. The present invention is based on the above knowledge. That is, the metal fine powder of the present invention is characterized in that it has an oxide film formed on the surface by ozone gas. According to the present invention, since the oxide film formed by the ozone gas is formed on the surface of the metal fine powder due to 200424028, the loss due to reduction from the oxide film is delayed, and the sintering start temperature of the metal fine powder is transferred to a higher temperature range. Based on the reduction of the shrinkage of the metal fine powder during sintering, the occurrence of delamination between the internal electrode layer and the dielectric layer can be suppressed. In addition, according to the present invention, the oxidation treatment of ozone gas in a low temperature region is performed, and the fine metal powders in the oxidation treatment are sintered with each other to prevent aggregation, thereby suppressing the internal electrode in the manufacturing step of the laminated ceramic condenser. The occurrence of structural defects such as short network. That is, when the metal fine powder of the present invention is mixed with an organic compound such as an organic solvent and an organic binder to form a metal fine powder paste, and used as an internal electrode of a multilayer ceramic condenser, the sintering start temperature is High temperature, little difference from the sintering starting temperature of the dielectric, reduces shrinkage and volume change between the dielectrics, and reduces agglomerated particles, making it possible to suppress delamination, cracks, and short-circuiting of internal electrodes during the manufacturing process The occurrence of structural defects. Therefore, according to the metal fine powder of the present invention, it is possible to reduce the thickness and reduce the resistance of the internal electrode accompanying the miniaturization and large capacity of the multilayer ceramic condenser. Among these fine metal powders, a thickness of the oxide film of 1 to 10 nm is desirable. When the thickness of the oxide film is less than 1 nm, the delay in the loss of the reduction of the oxide film cannot be fully achieved, so the sintering start temperature of the metal fine powder cannot be transferred to a higher temperature region, and as a result, the delamination cannot be suppressed. occur. When the thickness of the oxide film is more than 10 nm, the sinterability of the fine metal powder is reduced, which is not preferable. In order to make the prevention of delamination and the prevention of sinterability more effective, the thickness of the oxide film is preferably 2 to 10 nm, and more preferably 2 to 5 nm. Among the above-mentioned metal fine powders, the metal fine powder is gold of the present invention. 200424028 The fine powder of the metal is, for example, nickel. The conductive pastes such as copper and silver are suitable metal fine powders, metal fine powders such as aluminum, titanium, chromium, manganese, iron, cobalt, and bismuth, and alloy fine powders thereof. When used as an internal electrode of a multilayer ceramic condenser, a nickel fine powder which is excellent in electrical conductivity, can be fired in a reducing atmosphere, and is inexpensive is most suitable. Among these metal fine powders, it is desirable that a suitable metal fine powder has an average particle diameter of 1 m or less. In the case where the average particle diameter exceeds 1 #m, structural defects such as a reduction in sinterability or short-circuits between the internal electrodes of the multilayer ceramic condenser tend to occur, which is not preferable. In order to prevent the deterioration of the sintering property or the occurrence of structural defects, it is desirable that the average particle diameter of the metal fine powder is 0.5 µm or less. However, when the above average particle size is excessively small, the metal fine powders are sintered and agglomerated in the oxidation step of the present invention, and the lower limit of the above average particle size is 0. 1 μιη is what you want. Furthermore, in these metal fine powders, the ratio of the oxygen concentration of the metal fine powder to the thickness of the oxide film (oxygen concentration / thickness of the oxide film) is 0. 3 ~ 1. 0 is what you want. The oxygen concentration means the oxygen concentration of the metal fine powder containing the oxide film, and the thickness of the oxide film means the shape of the metal fine powder containing the oxide film as a virtual ball. The oxidation measured from the center to the radial direction Film thickness. The above ratio is below 0. In the case of 3, in order to make the oxide film easier to reduce, the above-mentioned delay of the loss of the oxide film cannot be fully achieved, so the sintering start temperature of the fine metal powder cannot be transferred to a higher temperature region. Layers happen. In the case where the above ratio exceeds 1 · 0 ', it is not preferable because the sinterability of the fine metal powder is reduced. In order to make these 200424028 delamination prevention and sinterability prevention more effective, the above ratio is 0. 3 ~ 0. 8 is better, 0 is better. 3 ~ 0 · 5ηιη is more preferable. The method for producing a metal fine powder according to the present invention is characterized in that the method for producing the metal fine powder described above is advantageous. The metal fine powder is treated in an aqueous solution of carbonic acid, and then subjected to an oxidation treatment in an ozone gas atmosphere to form an oxidation on the surface. Pellicle. According to the manufacturing method of the metal fine powder of the present invention, the oxide film formed by the ozone gas is formed on the surface of the metal fine powder, the loss due to the reduction of the oxide film is delayed, and the sintering start temperature of the metal fine powder is relatively low. The high-temperature region transfer and the shrinkage of the metal fine powder during sintering decrease, and delamination can be suppressed from occurring between the internal electrode layer and the dielectric layer. In addition, according to the present invention, the oxidation treatment of ozone gas in a low temperature region is used to prevent agglomeration caused by sintering of fine metal powders in the oxidation treatment, and the internal of the multilayer ceramic condenser manufacturing step is suppressed by suppressing The occurrence of structural defects such as short electrodes of the electrodes can reduce the thickness and reduce the resistance of the internal electrodes accompanying the miniaturization and large capacity of the multilayer ceramic condenser. In these methods for producing fine metal powders, it is desirable that the oxidation treatment is performed at a temperature range of 200 to 250 ° C. When the above-mentioned oxidation treatment is performed at a temperature lower than 200 ° C, since the sintering starting temperature of the metal fine powder needs to be high, it takes a long time for the oxidation treatment to form an oxide film, which is not practical. In addition, when the temperature is higher than 25 0 ° C, the oxidation treatment is performed until it reaches the inside of the metal fine powder, which may reduce the sinterability or increase the resistance of the internal electrodes of the multilayer ceramic condenser to radon. good. In order to prevent the formation time of the oxide film from being further shortened and the sinterability to be reduced, the oxidation treatment is required to be performed at a temperature range of 220 to 230 ° C -10- 200424028. Moreover, in the manufacturing method of the said metal fine powder, it is desirable to perform an oxidation process in the ozone concentration range of 1-20 volume%. When the oxidation treatment is performed at an ozone concentration lower than 1% by volume, the sintering starting temperature is shifted to a high temperature range. In order to obtain a strong oxide film, a long time oxidation treatment is required, which is not practical. When the oxidation treatment is performed at an ozone concentration of more than 20% by volume, the sinterability is liable to be reduced until the inside of the metal fine powder is rapidly oxidized, and as a result, the cost or price is relatively expensive and impractical. Also, in the method for producing a metal fine powder described above, the treatment in the aqueous carbonic acid solution is ρΗ5 · 5 ~ 6. The range of 5 is what you want. The treatment in carbonated water solution is below ρΗ5. When it is performed at 5 times, a non-uniform oxide film is formed on the surface of the metal fine powder to reduce the sinterability of the metal fine powder. When the dissolution of the metal fine powder itself stops, surface cracks occur. When it is carried out above ρΗ6.5, it is impossible to remove the hydroxide adhered to or absorbed on the surface of the metal fine powder, and the residual hydroxide after drying becomes an uneven oxide film. In order to further prevent these disadvantages, the treatment in the carbonic acid aqueous solution is performed in the range of ρ Η: 5 · 5 to 6 · 0. Furthermore, in these methods for manufacturing metal fine powders, metal fine powders, especially nickel, are practical due to their relatively inexpensive cost. The metal fine powders manufactured according to the above manufacturing methods are used in Electronic parts can be prevented from waiting. The occurrence of delamination described above gives a conductive paste. In the following, with reference to the drawings, suitable examples of the embodiment of the present invention will be further described in detail * with reference to examples of production of fine nickel powder. In addition, in addition to nickel, the metal fine powder produced by the method for producing a metal fine powder according to the present invention is applicable to various materials such as copper or silver paste, titanium composite materials, or catalysts. Uses of metal fine powder can also be used for the production of aluminum, titanium, chromium, manganese, iron, cobalt, uranium, bismuth and other metal fine powders. The metal fine powder of the present invention can be produced by a known method such as a gas phase method or a liquid phase method, in particular, a gas phase reduction method in which a metal chloride gas is brought into contact with a reducing gas to generate a metal fine powder, or Thermally decomposable metal compound spraying, thermally decomposing spray thermal decomposition method, the particle diameter of the generated metal fine powder can be easily controlled, and the method is preferable from the viewpoint that spherical particles can be produced more efficiently. In the nickel fine powder gas phase reduction method, a gas of nickel chloride gas can be reacted with a reducing gas such as hydrogen to heat and evaporate solid nickel chloride to generate nickel chloride gas. However, when considering the energy efficiency of the oxidation or moisture absorption of nickel chloride, the chlorine gas contacts the metallic nickel to continuously generate the nickel chloride gas. The nickel chloride gas is directly supplied in the reduction step, and then the reducing gas is used. The contacted nickel chloride gas system is continuously reduced, and a method for manufacturing nickel fine powder is advantageous. In the production process of nickel fine powder according to the gas-phase reduction reaction, nickel atoms are generated instantaneously when the nickel chloride gas comes into contact with the reducing gas, and the nickel atoms are caused to collide and agglomerate to generate and grow ultrafine particles. Therefore, the reduction step determines the particle size of the nickel fine powder to be produced according to conditions such as the partial pressure or temperature of the nickel chloride gas. According to the above method for producing nickel fine powder, when the amount of nickel chloride gas supplied to the reduction step is adjusted based on the amount of nickel chloride gas generated based on the amount of required chlorine gas supply amount, the nickel produced as described above The particle size of the fine powder can be controlled. In addition, the reaction of metal chloride gas from chlorine gas and metal is different from the method of generating metal chloride gas by heating and evaporation of solid metal chloride, which cannot reduce the use of -12-200424028 less carrier gas, according to Nor can it be used under manufacturing conditions. Therefore, in the gas-phase reduction reaction, when the amount of carrier gas used is reduced, the accompanying heating energy is reduced, and the reduction in manufacturing costs can be discussed. Further, by mixing an inert gas with the nickel chloride gas generated in the chlorination step, the partial pressure of the nickel chloride gas in the reduction step can be controlled. Therefore, the particle diameter of the nickel powder can be controlled by controlling the supply amount of the chlorine gas or the partial pressure of the nickel chloride gas in the reduction step, so that the particle diameter of the nickel fine powder can be stabilized and the particle diameter can be arbitrarily set at the same time. According to the manufacturing conditions of the nickel fine powder of the gas phase reduction method described above, the average particle diameter can be arbitrarily set to 1 // m or less. For example, the particle size of the starting nickel metal particles is about 5 to 20 mm. , Plate-like, etc. is preferred, and the purity is slightly 99. More than 5% is preferred. This metallic nickel is first reacted with chlorine gas to generate nickel chloride gas. At this time, the temperature is 800 ° C or higher for the reaction to proceed sufficiently, and the melting point of nickel is 1453 ° C or lower. When considering the reaction speed and the durability of the chlorination furnace, the practical range is 900 ° C to 1100 ° C. Then, the gaseous plutonium gas is directly supplied in the remote step, and is in contact with a reducing gas such as ammonia gas, and an inert gas such as nitrogen or argon is mixed with nickel chloride gas in an amount of 1-30 mol% Preferably, the mixed gas is introduced in the reduction step. Alternatively, the nickel chloride gas and all or independently of the chlorine gas may be supplied in the reduction step. For example, since the chlorine gas is supplied in the reduction step, the partial pressure of the nickel chloride gas can be adjusted to control the particle size of the nickel powder to be generated. If the temperature of the reduction reaction is higher than the temperature sufficient for the completion of the reaction, the formation of solid nickel powder is better because the treatment is preferably below the melting point of nickel. If economical considerations are taken, the temperature is 9 0 ° C ~ 1 1 0 ° C. Useful. After these reduction reactions are carried out to produce nickel fine powder, it is then cooled to -13-200424028 into nickel powder. When cooling, the primary particles of the nickel are agglomerated with each other to prevent the formation of secondary particles, to obtain the nickel powder of the desired particle size, and the gas flow of about 1 000 ° c to stop the reduction reaction is blown in. Inert gas such as nitrogen gas reaches about 400 ~ 800 ° C, and rapid cooling is required. Thereafter, the generated nickel powder is separated and recovered by, for example, a bag filter. In the method for producing a metal fine powder by a spray pyrolysis method, as a raw material of a thermally decomposable metal compound, specifically, a metal nitrate, sulfate, hydroxynitrate, hydroxysulfate, chloride, One or two or more of ammonium complexes, phosphates, carboxylates, and alkoxy compounds. An oil-containing solution containing the nickel compound is sprayed to form fine droplets, and water, alcohol, acetone, ether and the like can be used as a solvent at this time. The spraying method can be performed by a spraying method such as an ultrasonic wave or a double spray nozzle. These fine liquid droplets are heated at a high temperature to thermally decompose a metal compound to produce fine metal powder. The heating temperature at this time is a temperature at which the specific metal compound is thermally decomposed, and is preferably about the melting point of the metal. In the production method of metal fine powder by the liquid phase method, for example, in the production of nickel fine powder, an aqueous nickel solution containing nickel sulfate, nickel chloride, or a nickel complex is added to an alkali metal hydroxide such as sodium hydroxide, etc. The nickel hydroxide is produced by contact, and then the nickel hydroxide is reduced in a reducing agent such as tritium to obtain metallic nickel powder. The resulting metallic nickel powder may be subjected to a disintegration treatment as necessary in order to obtain uniform particles. The following is a detailed description of a method for producing nickel fine powder by contacting chlorine gas in metallic nickel to continuously produce nickel chloride gas. The nickel chloride gas is contacted and reduced with a reducing gas to produce nickel fine powder. -14- 200424028 A. Chlorination step Figure 1 shows an apparatus used in the present invention to produce fine metal powder. The chlorination step is preferably performed in a chlorination furnace 10 as shown in the figure. The upper end surface of the chlorination furnace 10 is provided with a supply pipe 11 for supplying raw material nickel (M). An upper side portion of the chlorination furnace 10 is connected to a chlorine gas supply pipe 12 and a lower side portion is connected to an inert gas supply pipe 13. A heating device 14 is arranged around the chlorination furnace 10, and a transfer pipe and nozzle 15 are connected to the other upper side of the chlorination furnace 10. The chlorination furnace 10 may be a vertical type or a horizontal type, but a vertical type is preferred in order to allow a solid-gas contact reaction to proceed uniformly. The chlorine gas flow meter was continuously introduced from the chlorine gas supply pipe 12. The transfer tube and nozzle 15 are connected to the upper end surface of the reduction furnace 20 described later, and the nickel chloride gas generated in the chlorination furnace 10 has the function of transferring the reduction furnace 20. The lower end portion of the transfer tube and nozzle 15 functions as a nickel chloride ejection nozzle in the reduction reduction furnace 20. Regardless of the form of the metallic nickel (M) as the starting material, from the point of contact efficiency and pressure loss prevention, granular, rough, and plate-like particles having a particle diameter of about 5 mm to 20 mm are preferred. The default is 99. More than 5% is preferred. The height of the metal nickel (M) filling layer in the chlorination furnace 10 is based on the supply rate of chlorine gas, the temperature in the chlorination furnace, the continuous operation time, the shape of the metal nickel (M), etc. The supply of chlorine gas changes the setting of the nickel chloride gas. It is better to be in a proper and adequate range. The temperature in the chlorinating furnace was 100 ° C or higher, and the melting point of nickel was 1483 ° C or lower. In consideration of the reaction speed and the durability of the chlorination furnace 10, a practical range of 900 ° C to 1100 ° C is preferred. In the method for producing a fine metal powder according to the present invention, the continuous supply of chlorine gas to the chlorination furnace 10 filled with nickel (M) is a continuous generation of nickel chloride gas. Therefore, based on the supply of chlorine gas, the amount of nickel chloride gas generated is controlled, and the reduction reaction described below is controlled by -15-200424028. This result can produce nickel fine powder as a target product. In addition, the chlorine gas supply is specifically explained by the following reduction steps. The nickel chloride gas generated in the chlorination step is transferred to the reduction furnace 20 through the transfer pipe and nozzle 15 and, depending on the location, the inert gas such as nitrogen or argon from the inert gas supply pipe 13 is relative to the nickel chloride gas system. 1 mol% to 30 mol% are mixed, and the mixed gas is transferred to the reduction furnace 20. Through the transfer pipe and nozzle 15 of the mixed gas in the preferred nickel chloride gas partial pressure, at full pressure 1. 0 is 0. 5 ~ 1. The range of 0, especially the manufacturing particle size of 0 · 2μιη ~ 0. In the case of nickel powder with a small particle size of 5μιη, a partial pressure of 0. 6 ~ 0. About 9 is better. Β. Reduction step The nickel chloride gas system generated by the chlorination step is continuously transferred to the reduction furnace 20. The reduction step is intended to use a reduction furnace 20 as shown in FIG. The reduction furnace 20 shown in the figure is formed into a cylindrical shape, the reduction is performed in the upper half, and the lower half is cooled. In the upper end portion of the reduction furnace 20, a nozzle (hereinafter simply referred to as a nozzle 15) attached to the above-mentioned transfer pipe and nozzle 15 projects below. Further, a reducing gas supply pipe (hydrogen gas supply pipe) 21 is connected to the upper end surface of the reduction furnace 20. A heating device 22 is disposed around the reduction furnace 20. The nozzle 15 is a nickel chloride gas (in the case of an inert gas) from the chlorination furnace 10 to the reduction furnace 20, and preferably, the flow velocity has a function of ejecting. When the reduction reaction between the nickel chloride gas and the hydrogen gas progresses, a combustion flame that forms a gaseous fuel such as LPG from the tip of the nozzle 15 extends to the lower flame F. The supply amount of hydrogen gas to the reduction furnace 20 is based on the chemical equivalent of the nickel chloride gas, in other words, it is 1 to the chemical equivalent of the chlorine gas supplied to the chlorination furnace 10. 0 -16- 200424028 ~ 3 · 0 times, preferably 1 · 1 ~ 2. About 5 times, it is not particularly limited. The temperature of the reduction reaction may be a temperature that is sufficient when the reaction is completed, and since it is easy to handle to produce solid nickel fine powder, it is preferably below the melting point of nickel. In addition, the temperature is practically 900 ° C to 11 ° C in consideration of the reaction rate, durability of the reduction furnace 20, and economy, and it is not particularly limited. As described above, the chlorine gas introduced into the chlorination furnace 10 is substantially the same amount of nickel chloride gas as the reducing raw material. By adjusting the linear velocity of the gas flow in accordance with the nickel chloride gas or a mixed gas of nickel chloride and an inert gas discharged from the nozzle 15, the particle size of the nickel fine powder P obtained can be appropriately adjusted. In other words, if the nozzle diameter is constant, the particle size of the nickel fine powder P generated in the reduction furnace 20 can be adjusted to the desired range by adjusting the amount of chlorine supplied to the chlorination step and the amount of inert gas supplied. Regarding the preferable linear velocity of the gas flow at the tip of the nozzle 15 (the total of the nickel chloride gas and the inert gas (calculated based on the gas supply amount at the reduction temperature)), at 900 ° C to 1 l0 ° The reduction temperature of C is set to about 1 m / sec to 30 m / sec. The linear velocity in the axial direction in the reduction furnace 20 for hydrogen gas is preferably about 1/50 to 1/3 00 of the ejection speed (linear velocity) of the nickel chloride gas, and 1/80 to 1/2 50 is Better. Therefore, the nickel chloride gas system in a substantially static hydrogen atmosphere is ejected from the nozzle 15. The outlet direction of the reducing gas supply pipe 21 is preferably not facing the flame F side. Further, as the reducing gas used in the production of the nickel fine powder, a hydrogen sulfide gas other than the above-mentioned hydrogen gas can be used. In consideration of the influence on the nickel fine powder to be produced, a hydrogen gas is suitable. Furthermore, in the case of producing nickel fine powder, the metal chloride gas is in contact with the reducing gas, and the reduction reaction temperature range of the 17-200424028 reaction is usually 900 to 120 ° C, but preferably 950 to 1100 ° C. And more preferably 980 ~ 1050 ° C. C. Cooling step The nickel fine powder produced in the reduction step is cooled in a space portion (lower portion) opposite to the nozzle 15 in the reduction furnace 20 as shown in FIG. 1. A preferred example of cooling is an embodiment in which the space below the tip of the flame F is blown into a cooling inert gas through a cooling gas supply pipe 23. In addition, the so-called cooling in the present invention is an operation performed to suppress or stop the growth of nickel particles in a gas stream (including hydrochloric acid gas) generated by the reduction reaction, and specifically means that the reduction reaction is terminated at about 1000 ° C The gas flow is rapidly cooled to about 400 ° C ~ 800 ° C. Needless to say, cooling to a temperature below this may be performed. In order to cool the inert gas of the produced nickel fine powder, there is no particular limitation as long as it does not affect the produced nickel fine powder. Nitrogen gas, argon gas, or the like can be used. Among them, nitrogen gas is suitable because it is cheap. The supply amount of the inert gas for cooling is usually 5N1 / min or more, preferably 10 to 50N1 / min, per 1 g of nickel fine powder. The temperature of the supplied inert gas is usually 0 to 100 ° C, but it is more effective when the temperature is 0 to 80 ° C. D. Each step of the chlorination, reduction, and cooling in the recovery step is a mixed gas of nickel fine powder P, hydrochloric acid gas, and inert gas, which is sequentially passed, and is transferred to a recovery furnace (not shown) through the nozzle 24 in FIG. The nickel fine powder P is separated and recovered from the mixed gas. In the separation and recovery, one type or a combination of two or more types such as a bag filter, a water absorption separation device, an oil absorption separation device, and a magnetic gas separation device are suitable, but are not particularly limited. Also, before or after separation and recovery, the nickel fine powder produced may be washed with a solvent such as water or a monovalent alcohol having 1 to 4 carbon atoms, if necessary. Furthermore, if necessary, the generated nickel fine powder is subjected to a hydrogen reduction treatment in a reducing atmosphere of a hydrogen gas diluted with a hydrogen gas or an inert gas, and the oxygen content in the nickel fine powder may be slightly adjusted. The hydrogen reduction treatment temperature is 220 ~ 300. (: Better, 250 to 300 ° C is more preferred. Hydrogen reduction treatment time is 5 to 60 minutes. E · Oxidation treatment step The nickel fine powder in the present invention is a nickel fine powder obtained by the method described above in carbonic acid. Treatment in an aqueous solution, followed by heating and oxidation treatment in an ozone atmosphere. Carbonic acid aqueous solution treatment is performed by blowing carbon dioxide gas in a metal nickel fine powder slurry to adjust pH 5. 5 ~ 6. 5. The carbonic acid aqueous solution is treated at room temperature for 60 minutes. The oxidation treatment is obtained by a gas phase reduction method, and the nickel fine powders dried after the application of a carbonic acid aqueous solution are placed in an oxidation furnace and heated, and ozone gas is supplied in the oxidation furnace. Ozone gas can be mixed with oxygen, air, carbon monoxide, carbon dioxide, or other gases, or water vapor, lower alcohol, and the like, and it is more effective to supply it with a mixed oxygen system. The range of the ozone gas concentration is suitably 1 to 20% by volume, and more preferably 5 to 20% by volume. The oxidation treatment temperature is suitably in a low temperature range of 200 to 250 ° C, and is preferably in a range of 220 to 230 ° C. The oxidation treatment time is appropriately selected in the range of 1 minute to 30 minutes if the thickness of the oxide film is 1 to 10 nm in accordance with the aforementioned ozone gas concentration and oxidation treatment temperature. The nickel fine powder obtained by the gas-phase reduction method, because it is placed in the air, will absorb nickel to generate nickel hydroxide. When these nickel fine powders are mixed with an organic solvent or the like as a nickel paste, as a result, the dispersibility is lowered, the nickel fine powders agglomerate with each other, and the coarse powder is added, so that the heat treatment for removing nickel hydroxide takes a long time. Therefore, in the case where the nickel fine powder obtained by the gas phase reduction method is subjected to an oxidation treatment, the faster the above-mentioned oxidation treatment is generated, the better. After the oxidation treatment, hydrogen reduction treatment may be performed in a hydrogen atmosphere as required or a hydrogen gas atmosphere diluted with an inert gas, and the oxygen content in the nickel fine powder may be slightly adjusted. E. Preparation of conductive paste The fine metal powder obtained as described above is preferably a conductive paste or a paste for electrode formation. These fine metal powders are kneaded with an organic solvent and a binder to form a paste. Organic solvents (organic colorants) are sufficient if the former conductor paste is used. For example, ethyl cellulose, ethylene glycol, toluene, xylene, mineral oil, butylcarbitol, terpineol, etc. can be used. High boiling organic solvents. The binder is an organic or inorganic binder, and a high-molecular binder such as ethyl cellulose is preferred. Also, if necessary, glass frit such as lead-based glass, zinc-based glass or silicate-based glass, or metal oxide materials such as manganese oxide, magnesium oxide, bismuth oxide, etc., can also be formed. Mix during mixing. When these additives are mixed and applied to a substrate such as ceramics, when the electrode is sintered to form an electrode, a highly conductive electrode with excellent adhesion to the substrate can be formed, and the wettability with solder can be improved. In addition, a plasticizer, a dispersant, or the like may be added to the paste. As described above, a solid oxide film is formed on the surface of the metal fine powder by ozone gas, and a coarse powder having a high sintering initiation temperature and shrinkage during sintering can be obtained. It is a fine metal powder that reduces the metal paste formed by mixing with an organic solvent and the like, and has excellent dispersibility and has a suitable function as an internal electrode of a laminated ceramic condenser. By using these fine metal powders, structural defects such as delamination in the manufacturing steps of the multilayer ceramic condenser can be controlled. [Embodiments] Examples Hereinafter, the effects of the present invention will be clearly described based on the examples of the present invention. Evaluation of the sintering start temperature of nickel powder [Example 1] In the chlorination furnace 10 of the metal nickel fine powder manufacturing apparatus shown in Fig. 1, the metal nickel fine powder having an average particle diameter of 5 mm from the starting material is supplied from the raw material supply pipe. Fill with 11 1 and change the temperature of the atmosphere in the furnace of the heating device 14 to 110 G ° C. Then, the chlorine gas from the chlorine gas supply pipe 12 is supplied into the chlorination furnace 10 to chlorinate metallic nickel to generate nickel chloride gas. In this nickel chloride gas, a nitrogen gas supplied with a chlorine gas supply amount of 10% (molar ratio) is mixed by an inert gas introduction pipe 13 provided at a lower portion of the chlorination furnace 10. Therefore, a mixed gas of nickel chloride gas and nitrogen gas is introduced into the reduction furnace 20 through the nozzle 15. Then, the reduction step is a mixture of nickel chloride gas and nitrogen gas ’in a reduction furnace 20 that is heated to a temperature of 1 000 ° C in the furnace by a heating device 22, and is passed through a nozzle 15 at a flow rate of 2. 3m / s (1000 ° C conversion) import. At the same time, the hydrogen gas from the reducing gas introduction pipe 41 provided in the upper end portion of the reduction furnace 20 was supplied into the reduction furnace 20 at a flow rate of 7 N1 / min to reduce nickel chloride gas' to obtain nickel fine powder P. In addition, the cooling step is to contact the nickel fine powder P generated in the reduction step with -21-200424028 to be supplied by a cooling gas provided at the lower side of the reduction furnace 20; 1 6. Nitrogen gas supplied and supplied at 4N1 / min · g, and the nickel fine powder P produced by cooling the nickel fine powder P was passed into a recovery furnace (not shown) together with chlorine gas and hydrochloric acid vapor. The nitrogen gas, salt, and nickel fine powder P introduced by the recovery furnace of the nozzle 24 are introduced into a bag filter (not shown) and separated. Therefore, the recovered nickel fine powder P was washed with hot water, and carbon dioxide gas was blown into the slurry to adjust PH5. 5. At room temperature, the nickel micro carbonic acid aqueous solution was released for 60 minutes. The nickel fine powder treated with the carbonic acid aqueous solution was dried and processed. The nickel fine powder P obtained by the gas phase reduction method was charged into an oxidation furnace, and the temperature inside the furnace was set to 200 ° C. The supply gas from an oxidizing gas containing 5% by volume of an ozone-oxygen mixed gas system was conducted for 10 minutes to conduct nickel treatment. Powder P to obtain nickel fine powder. [Example 2] When the nickel fine powder p produced in the same manner as in Example 1 was oxidized, the atmosphere temperature in the oxidation furnace was 250C, the ozone concentration of ozone-oxygen mixed oxygen was 5 vol%, and the oxidation treatment time was 30 minutes. . [Comparative Example 1] Nickel fine powder P was produced in the same manner as in Example 1, and an oxidation treatment was applied to a liquid treatment which was not performed. Used as oxidizing gas during oxidation treatment. It should be noted that the oxidation treatment temperature and the oxidation treatment time were performed under the same conditions. [Comparative Example 2] Give tube 23 with. Therefore, the nozzle 24 conducts acid vapor, and collects nickel fine powder and nickel fine powder powder. The ozone in the heating tube is placed in the oxidation place, and the oxygenation step is performed in the oxidation step of the oxidized gas. The same system is used for oxygen river -22-22 200424028 The nickel fine powder p was produced in the same manner as in Example 1, and an oxidation treatment was applied to the carbonic acid aqueous solution. When oxidizing, oxygen gas is used as the oxidizing gas system. The oxide film and the oxygen concentration 'having the same thickness as the nickel fine powder obtained in Example 1 were carried out at an oxidation treatment temperature of 400 ° C and an oxidation treatment time of 30 minutes. In Examples 1 and 2 and Comparative Examples 1 and 2, the oxide film thickness, oxygen concentration, sintering initiation temperature, shrinkage rate, and particle size distribution of the metallic nickel fine powder were measured by the following methods. 1) Oxide film thickness First, the metallic nickel fine powder is directly vibrated on the mesh of the copper sheet of the stretched cotton wool film, and then carbon is vapor-deposited to prepare a measurement sample. Then, a 200 kV electrolytic radiation type transmission electron micromirror (HF-2000, manufactured by Hitachi, Ltd.) was used to observe the grid image of the measurement sample, and the thickness of the oxide film on the surface of the metallic nickel fine powder was measured. 2) Oxygen concentration: Fill nickel fine powder with nickel into a capsule made of nickel, put it into a ytterbium lead crucible, and heat it to 500 ° C in an argon atmosphere. Carbon monoxide generated at this time is quantified by IR to determine Oxygen concentration in metallic nickel fine powder. 3) Mix 1g of metallic nickel powder, 3% camphor, 3% acetone, and fill it into a cylindrical metal with an inner diameter of 5mm and a height of 10mm. The treated surface pressure is 1 ton. Make test samples. The sintering onset temperature of this test sample was measured using a thermal expansion and contraction behavior measuring device (TMA-8310, manufactured by Rica Co., Ltd.) in a weakly reducing atmosphere (1. 5% hydrogen-98. 5% nitrogen mixed gas) atmosphere was performed under the condition of a temperature increase rate of 5 ° C / min. In the shrinkage curve obtained by the measurement described in the above -23-200424028, the temperature at the time of 1% shrinkage is used as the sintering start temperature. 4) Shrinkage rate The shrinkage rate curve obtained by measuring the sintering initiation temperature of 3) above is the shrinkage rate based on the weight reduction rate at the time of heating to 500 ° C. 5) The particle size distribution was measured using a viscosity measuring device LS 23 0 (manufactured by Kurota Co., Ltd.). The sample was suspended in cyclohexanol (isopropyl alcohol 10%, ethanol 90%) and dispersed in a homogenizer for 3 minutes. A particle diameter (D50) of 50% by volume in the cumulative particle size distribution was obtained. Table 1 shows the measurement results of the oxide film thickness, oxygen concentration, sintering start temperature, shrinkage rate, and particle size distribution of the nickel fine powder obtained in Examples 1 and 2 and Comparative Examples 1 and 2. Table 1 Oxidation conditions _ Measurement results Oxidation gas oxidation temperature (° C) Oxidation time Fen) Oxide film thickness (nm) Oxygen concentration Oxide film density *) Sintering start temperature (° C) Shrinkage (%) Particle size distribution Example 1 5 vol% ozone 200 10 51. 65 0. 33 380 6. 0 0. 86 Example 2 5 vol% ozone 250 30 96. 21 0. 69 450 4. 3 1. 12 Comparative Example 1 Oxygen 200 10 1 0. 22 0. 22 220 8. twenty one. 55 Comparative Example 2 Oxygen 400 30 51. 20 0. 24 330 6. 5 2. 05 *) Oxide film density: ratio of oxygen concentration to oxide film thickness (oxygen concentration / oxide film thickness) It is apparent from Table 1 that the nickel fine powder obtained in Examples 1 and 2 is compared with Comparative Example 1 and The nickel fine powder obtained in 2 has an oxide film thickness of -24-200424028 degrees, which is slightly larger, which also has a large amount of oxygen content, and also has a high sintering start temperature, which is $ _j, or ° in other words. Examples The comparison between the medium nickel fine powder and the nickel fine powder of each comparative example is that it is determined that a sufficient oxide film is obtained because the sintering behavior is firmly improved. Moreover, each particle size distribution (ratio of coarse particles) of the obtained nickel fine powder obtained a number smaller than that of each comparative example. In particular, since Comparative Example 2 has a large particle size distribution, it can be subjected to a long-term oxidation treatment at a high temperature. Evaluation of the Dispersibility of Nickel Paste [Example 3] 50% by mass of 50% by mass of nickel fine powder obtained by the oxidation treatment of ozone gas with 5% by mass of ethyl cellulose and 95% by mass of terpineol obtained in Example 1 The% color developing material 'was kneaded in a 3-roll machine to make a paste, and this was applied to determine a film density. [Comparative Example 3] The nickel fine powder obtained in Comparative Example 2 was subjected to oxygen oxidation treatment, and nickel fine powder having the same oxygen concentration as the oxide film having the same thickness as the nickel fine powder obtained in Example 1 was used. A paste was prepared and applied to measure the film density. Table 2 shows Example 3 and comparison. Measurement results of the film density of the paste obtained in Example 3. Example 2 Film Density Example 3 5.0 g / cm3 Comparative Example 3 3,5 g / cm3 According to Table 2, the paste system of Example 3 has a higher density than that of Comparative Example 3 and can be judged Good dispersibility. Therefore, when the paste of Example 3 is used as an internal electrode of a laminated -25-200424028 ceramic condenser, the effect of suppressing structural defects such as cracks and delamination can be obtained. As described above, according to the production technology of the metal fine powder of the present invention, the surface of the metal fine powder is formed with an oxide film by ozone gas, and the loss due to the reduction of the oxide film delays the sintering start temperature of the metal fine powder to The higher temperature range and the shrinkage rate based on the fine metal powder during sintering can reduce the delamination between the internal electrode layer and the dielectric layer. Therefore, it is expected that the conductive paste used in electronic parts and the like of the present invention is suitable for producing fine metal powders. [Brief Description of the Drawings] Fig. 1 is a view showing an apparatus for producing fine metal powder used in the present invention. Description of component symbols Table 10 ... Chlorination furnace 11 ... Raw metal nickel (M) supply pipe 12 ... Chlorine gas supply pipe 1 3 ... Inert gas supply pipe 1 4 ... Heating device 15 ... Transfer pipe and nozzle 20 ... Reduction furnace 21 ... Reduction Gas supply pipe 22 ... Power mouth heating device 23 ... Cooling gas supply pipe 24 ... Nozzle M ... Raw metal nickel-26- 200424028 F ... Light flame
P···鎳微粉末P -27P ··· Ni fine powder P -27