JP4240454B2

JP4240454B2 - Titanium-based hard sintered material, manufacturing method thereof, and plain bearing using the titanium-based hard sintered material

Info

Publication number: JP4240454B2
Application number: JP2002359959A
Authority: JP
Inventors: 賢治中原; 州一今里; 茂也坂口
Original assignee: Nippon Tungsten Co Ltd
Current assignee: Nippon Tungsten Co Ltd
Priority date: 2002-12-11
Filing date: 2002-12-11
Publication date: 2009-03-18
Anticipated expiration: 2022-12-11
Also published as: JP2004190097A

Description

【０００１】
【発明の属する技術分野】
本発明は、耐食性および強度を何等損なうことなく、耐摩耗性と摺動特性が改善されたチタン基焼結材料とその製造法、ならびに、そのチタン基焼結材料を用いたすべり軸受に関する。
【０００２】
【従来の技術】
本願出願人は、先に、特許文献１において、耐食性を損なうことなく、高硬度化することによって、耐摩耗性と強度を改善したチタン基焼結合金とそれを用いたすべり軸受を開示した。
【０００３】
このチタン基焼結合金は、ＴｉＣあるいはＴｉＮ、または、これらの固溶体Ｔｉ（Ｃ，Ｎ）の硬質物質を５〜７体積％と、残部が、Ｖａ族、ＶＩａ族金属元素、Ｔｉ、それら相互の固溶体、および、それらの炭化物、窒化物および炭窒化物の中の一種または二種以上からなる第１部分と、Ｔｉからなる第２部分とからなるもので、その第１部分が１〜３０体積％を占めるものである。そして、このチタン基焼結合金は、Ｔｉが有する耐食性を劣化することなく、耐摩耗性と強度が改善され、その代表例として、Ｔｉ−（Ｃｒ，Ｖ）−ＴｉＣの組成は、従来のＴｉ−Ｍｏ−ＴｉＣ系と比較して高強度であるため、過酷な環境で使用されるすべり軸受に好適に適用されるものである。
【０００４】
【特許文献１】
特開平６−７３４８６号公報
【０００５】
【発明が解決しようとする課題】
前記従来技術において、原材料として使用されていたＴｉとＴｉＣあるいはＴｉＮにおいて、それぞれのＴｉＣとＴｉＮにおけるＴｉに対するＣとＮのモル比を、ｘとｙとしてＴｉＣｘとＴｉＮｙとして表わした場合、ｘ＝１．０、ｙ＝１．０であった。例えば、Ｔｉ−Ｍｏ−ＴｉＣ系焼結合金を例に採れば、焼結に際して、ＴｉＣ中のＣがＴｉおよびＭｏ側との間で相互拡散し、焼結後、最終的にはＴｉＣ０．５相当のＴｉＣ相とＴｉ−Ｍｏ合金相（β−Ｔｉ相）となる。そして、粗大なＴｉ原料粉末、例えば、粒径４５ミクロン以下を多く含む場合には、さらにＣが拡散してＴｉＣ１．０からＴｉＣ０．５に変わる過程でＴｉＣｘ相の著しい粒成長を伴うため、硬度および強度を低下させていた。さらに、粗大なＴｉ原料粉末に代えて微細なＴｉ粉末を使用しようとすれば、Ｔｉ自身が活性であるため製造が非常に困難であり、さらには、固溶酸素量や窒素量によって大きく物性が劣化するため、工業的な適用ができなかった。
【０００６】
そして、上記従来のチタン基硬質焼結材料を海水中で使用される縦軸ポンプの水中すべり軸受に適用したときには、耐食性と耐摩耗性の不足から、短期間で交換が必要となっていた。
【０００７】
本発明が解決しようとする課題は、上記従来のチタン基硬質焼結材料の耐食性と、耐摩耗性と強度の改善にあって、海水用縦軸ポンプの海水中軸受のような過酷な条件下で使用されるすべり軸受にも好適に使用できるチタン基焼結硬質合金およびその製造法ならびにそのチタン基硬質焼結材料を使用したすべり軸受を提供するものである。
【０００８】
【課題を解決するための手段】
本願発明のチタン基焼結合金は、ＴｉＣｘあるいはＴｉＮｙにおける、ｘあるいはｙは、それぞれ０．５〜０．９であって、１．０よりも小さい数値である。そして、残部が、Ｖａ族金属元素、ＶＩａ族金属元素、Ｔｉ、Ｖａ族金属元素・ＶＩａ族金属元素・Ｔｉ相互の固溶体、ならびに、Ｖａ族金属元素・ＶＩａ族金属元素・Ｔｉの炭化物、窒化物および炭窒化物の中の一種または二種以上からなる。
【０００９】
そして、焼結後、微細なＴｉＣｘ’（ｘ’＝０．５〜１．０）、ＴｉＮｙ’（ｙ’＝０．５〜１．０）またはＴｉＣとＴｉＮの固溶体のいずれか一種または二種以上が５〜９５体積％からなる焼結体が形成される。
【００１０】
この焼結体において、耐摩耗性の改善のためには、少なくとも、５体積％が必要で、また、すべり軸受等の部材として必要な強度と摺動特性が維持するためには、９５体積％以下に維持する必要がある。
【００１１】
本発明においては、あらかじめ、ｘとｙとが、それぞれ、０．５〜０．９であるＴｉＣｘ、あるいはＴｉＮｙ粉末を原材料として用いることによって、硬度および強度を低下させる粒成長を伴う粗大なＴｉ原料粉末量を極力小さく、あるいは削除することができる。
【００１２】
また、ＣやＮは侵入型原子であるため、Ｖａ族、ＶＩａ族金属元素およびＴｉと比較してはるかに拡散速度も速く、より低温から拡散速度が大きくなるため、焼結性が著しく改善され、より低温で緻密化が可能となる。さらにｘとｙとが、それぞれ、０．５〜０．９であるＴｉＣｘ、あるいはＴｉＮｙ粉末自体は容易に微細な粉末が得られ、しかも、さらに焼結性の改善をもたらし、さらには、焼結体の硬度および強度を向上できる。
【００１３】
さらには、Ｔｉ相に固溶する成分元素を炭化物、窒化物、炭窒化物の形で添加すると、炭化物等の分解反応が焼結緻密化の過程で並行して生じ、その後固溶はするが、この分解・固溶反応には時間がかかる。これによって、Ｔｉ中のこれらの溶質濃度は上がりにくく、好適な組成をコントロールでき、物性を向上させることが可能となる。
【００１４】
この本発明に係るチタン基硬質焼結合金は、耐摩耗性および耐食性において極めて優れたものであって、化学工業・機械工業において金型、ポンプ部品、軸受、メカニカルシール、弁、パイプ、攪拌機、混合機、刃物などに好適に使用できる。
【００１５】
とくに、本発明に係るチタン基硬質焼結合金をすべり軸受に適用する場合には、一方の摺動部材を本発明のチタン基焼結合金で形成し、他方の摺動部材をセラミックスあるいはエンジニアプラスチックで形成してすべり軸受を構成することによって、海水中に浸漬させた状態でも、耐摩耗性に優れているとともに耐食性にも優れたすべり軸受が得られる。
【００１６】
前記本発明に係るチタン基硬質焼結合金を、とくに、海水用縦軸ポンプの海水中軸受のような過酷な条件下で使用される回転摺動部材と固定側摺動部材とからなるすべり軸受に使用する場合は、本発明に係るチタン基硬質焼結合金を回転摺動部材と固定側摺動部材の何れかの部材に適用し、他方の部材を窒化ケイ素または炭化ケイ素を主成分とするセラミックス、または、ＰＴＦＥ（四フッ化エチレン樹脂）、または、ＰＥＥＫ（ポリエーテルエーテルケトン樹脂）を主成分とすることができる。
【００１７】
また、回転摺動部材として本発明のチタン基硬質焼結材料を使用する場合は、本発明のチタン基硬質焼結材料によって形成した軸受スリーブを回転軸に嵌入固定し、固定側摺動部材は、窒化ケイ素または炭化ケイ素を主成分とするセラミックス、または、ＰＴＦＥ（四フッ化エチレン樹脂）、または、ＰＥＥＫ（ポリエーテルエーテルケトン樹脂）を主成分とするエンジニアプラスチックで形成したブッシュと、同ブッシュを軸方向に長い筒状の弾性部材の内周面に密着固定し、同弾性部材を筒状の金属シェルの内周面に密着固定し、前記ブッシュと内径が等しい部分と外側に向けて内径をテーパー状に拡大する部分とを有する筒状の保護ピースを、前記弾性部材の内周面で前記ブッシュの軸方向両端にそれぞれ固定し、前記金属シェルを軸受ケースに固定したものとすることができる。この場合、この保護ピースがブッシュ内に回転側摺動部材が嵌入固定された軸を挿入する際のガイドとして作用し、軸先端部がブッシュの端部に直接接触して、ブッシュの縁が欠ける等の破損が防止され得る。
【００１８】
係るすべり軸受は、無潤滑条件下、すなわち大気中において摺動される場合であっても、極めて安定した摺動特性を有し、また海水などの流体下の潤滑がなされる条件下においてもさらに優れた摺動特性を有する。さらに、ケイ砂やアルミナ微粒子等の固形物が混入された水中で用いられる場合であっても、耐摩耗性に優れている。そこで、砂等の硬い固形物が混入する海水を取り扱う縦軸ポンプ等の水中軸受として好適である。
【００１９】
とくに、スラリー濃度が高く耐摩耗性を要求される場合は一方の摺動部材にセラミックスを用い、ドライ運転時間が長く、固体潤滑、流体潤滑双方の条件下での摺動特性を要求される場合にはエンジニアプラスチックを用いると本発明の特徴がより生かせる。
【００２０】
【発明の実施の形態】
以下、実施例に基づいて本発明の実施の形態を説明する。
【００２１】
実施例１
この実施例は、本発明に係るチタン基硬質焼結材料そのものの特性を示す実施例である。
【００２２】
市販のＴｉＣｘ（Ｘ＝０．５〜０．９）および／またはＴｉＮｙ（Ｙ＝０．５〜０．９）・Ｔｉ・Ｍｏ・Ｗ粉末等を所定割合に配合後、らい潰機にて１時間混合し、２０００ｋｇｆ／ｃｍ^２にてプレス成形した。これを１２５０〜１５００℃にて真空雰囲気中で２時間焼結した。配合組成を表１に示すように変化させた。得られた焼結体について硬さ（ＨＲＣ）と強度（３点曲げ抗折力・ＧＰａ）、さらに耐食性を調べた。耐食性は大気開放下で乾電池合剤（２５℃）に７日間浸漬して腐食速度から評価し、その結果を、○：０．０５ｍｍ／年以下、△：０．１ｍｍ／年以下、×：０．１ｍｍ／年超として表２に示した。
【００２３】
【表１】

【表２】

本発明の実施例である１〜４は、従来のＴｉＣ１．０および／またはＴｉＮ１．０原料粉末を使用した比較合金２１〜２４に比し、高硬度および高強度であり、耐食性も同等以上であることから、耐食耐摩耗性に優れていることが判る。
【００２４】
本発明の実施例５〜６は、従来のＴｉＣ１．０原料粉末を使用した比較合金２５に比し、高硬度および高強度であり、耐食性も同等以上であることから、耐食耐摩耗性に優れていることが判る。比較例として示した比較合金２６のＴｉ（ＪＩＳ２種）と比較して、非常に高硬度であるため耐摩耗性に優れている。同じく比較合金２７のＷＣ−１．０ｍａｓｓ％Ｃr−８Ｎｉ超硬合金と比較して、著しく耐食性に優れたものである。
【００２５】
以上から、本発明は比較例に比し、総合的に優れていることが明らかである。
【００２６】
実施例２
表３は、周期律表ＶａおよびＶＩａ族金属元素およびそれら相互の固溶体の炭化物、窒化物、炭窒化物の一種以上を含む本発明合金１１〜１８の組成と焼結温度を示し、また、表４はその硬さ、強度および耐食性等の特性と、総合判定結果を示す。
【００２７】
【表３】

【表４】

本発明合金１１〜１８は比較合金２１〜２７に対して、耐摩耗性が優れ、さらに強度と耐食性を兼ね備えているため、総合的に優れることは明らかである。
【００２８】
なお、本発明合金は中性および酸性（非酸化性酸：塩酸・硫酸など、酸化性酸：硝酸など）に対して優れた耐食性を示す。とくに、本発明合金１・１１〜１４はＶ・Ｎｂ・Ｔａの３元素のいずれかを含む合金であるが、これらは酸化性酸に対して他の本発明合金と比較して、さらに優れた耐食性を示した。すなわち、これらＶ・Ｎｂ・Ｔａの３元素のいずれかを含む本発明合金は、酸化性酸に対して特に良好な耐食性を有する。
【００２９】
さらに、９００℃×１時間の酸化増量試験（大気中）を実施したところ、Ｎｂ・Ｔａを含む本発明合金１・１１〜１３は、比較合金２１〜２７に対しても勿論、Ｎｂ・Ｔａを含まない本発明合金２〜６・１４〜１８をよりも２〜９倍の優れた耐酸化性を示した。すなわち、Ｎｂ・Ｔａを含む本発明合金は、特に良好な高温耐酸化性を有する。
【００３０】
実施例３
この実施例は、本発明に係るチタン基硬質焼結合金を海水用縦軸ポンプの水中軸受としてのすべり軸受に適用した例を示す。
【００３１】
図１は、本発明に係るチタン基硬質焼結合金を使用したすべり軸受の縦断面構造を示す図であり、図２は、図１のＡ−Ａ矢視断面図である。
【００３２】
これらの図において、１は回転側摺動部材を示し、２は固定側摺動部材を示す。
【００３３】
回転側摺動部材１の回転軸１０には、実施例１に示すチタン基硬質焼結合金で形成された筒状の軸受スリーブ１２を嵌入している。そして、軸受スリーブ１２は、回転軸１０に設けられた段差部１４で軸方向位置が規制され、またスリーブキー１６で軸回りの相対回転が規制され、さらに、スリーブ押さえ１８で軸方向の抜けが規制されて回転軸１０に嵌入固定される。
【００３４】
固定側摺動部材２は、筒状の金属シェル２０の内周面に、硬質ゴム等からなる筒状の弾性部材２２が密着して強固に嵌入されると共に適宜に接着固定され、さらに、この弾性部材２２の内周面に、軸方向の長さが弾性部材２２より短い筒状のブッシュ２４が密着嵌入される。このブッシュ２４は、炭化ケイ素（ＳｉＣ）または窒化ケイ素（Ｓｉ_３Ｎ_４）を主成分とするセラミックス、あるいはＰＴＦＥまたはＰＥＥＫを主成分とするエンジニアプラスチックで形成される。さらに、弾性部材２２の内周面でブッシュ２４の軸方向両端に、ＰＴＦＥ等のプラスチック材からなる筒状の保護ピース２６、２６が固定される。これらの保護ピース２６、２６は、ブッシュ２４と内径が等しい部分と外側に向けて内径をテーパー状に拡大する部分とを有する。そして、これらの金属シェル２０、弾性部材２２、ブッシュ２４および保護ピース２６、２６の組付け材が、軸受ケース２８に嵌合挿入され、さらに取付ネジ３０、３０により位置決め固定が行われる。なお、ブッシュ２４の内周面には、軸方向に複数本の溝３２、３２が設けられている。
【００３５】
図３は、本発明の上記すべり軸受を縦軸ポンプの水中軸受として適用した例を示す。図において、図示しないモータによって回転駆動される回転軸１０が揚水管４０内の軸心位置に配置され、この回転軸１０の適宜な中間部が、本発明のすべり軸受４２、４２によって、揚水管４０に回転自在に支持される。
【００３６】
かかる構造において、図１のごとく、軸受スリーブ１２等が組み付けられた回転軸１０を軸受ケース２８に組み付けられたブッシュ２４内に挿通する際に、保護ピース２６のテーパ状部分および等しい内径の部分がガイドとして作用し、ブッシュ２４の端部に回転軸１０の先端部が直接接触するようなことがない。このために、セラミックスあるいはエンジニアプラスチックで形成されて比較的に脆いブッシュ２４が、回転軸１０の組み付け作業により縁が欠ける等の破損を防止できる。それだけ、組み付け作業が容易である。
【００３７】
そして、図３のごとく縦型ポンプの水中軸受として本発明のすべり軸受を応用するならば、水中軸受としてゴム軸受等の起動する際に潤滑水を必要とする装置に比較して、潤滑水を供給するための設備およびシャフト保護管等が不必要であって、ポンプ設備全体を大幅に簡素化し得る。
【００３８】
次に、この水中軸受として本発明のすべり軸受の耐食性を調べるために以下の実験を行った。回転側摺動部材を本発明のチタン基硬質焼結材料と従来材である比較合金２３で形成し、固定側摺動部材を２種類のセラミックス（ＳｉＣとＳｉ_３Ｎ_４）で形成したすべり軸受で比摩耗量について比較した。実験条件は、軸受面圧１ｋｇｆ／ｃｍ^２（９．８Ｎ／ｃｍ^２）、周速４．７ｍ／ｓ、海水＋砂混合液（砂濃度２０００ｐｐｍ）、実験時間１００時間である。
【００３９】
この測定結果を図４に示す。同図から明らかなごとく、固定側摺動部材をセラミックとした場合、従来材である比較合金２３とセラミックスの組合せからなるすべり軸受と比較して、本発明のチタン基硬質焼結材料とセラミックスの組合せからなるすべり軸受の比摩耗量は約１／４以下であった。
【００４０】
一方、固定側摺動部材をＰＴＦＥ樹脂を主成分とするエンジニアプラスチックとした場合、従来材である比較合金２３との組合せからなるすべり軸受と比較して、本発明のチタン基硬質焼結材料とＰＴＦＥ樹脂を主成分とするエンジニアプラスチックの組合せからなるすべり軸受の比摩耗量は約１／５以下であった。また硬さの関係よりその摩耗量はチタン基硬質焼結材料に比べエンジニアプラスチックの方が多くなっていた。
【００４１】
これにより、一方の摺動部材をチタン基硬質焼結合金で形成し、他方の摺動部材をセラミックスで形成する本発明のすべり軸受は、海水に対する耐食性が優れているとともに、耐摩耗性も優れていることが確認された。
【００４２】
上記の実施例においては、本発明のすべり軸受を縦軸ポンプの水中軸受として応用する一例を示したが、これに用途が限られるものではなく、液体中または気体中で用いられるすべり軸受、さらに、一般回転機械に用いるすべり軸受、無潤滑条件下で用いられるすべり軸受等のいずれに応用しても良い。また、回転側摺動部材をセラミックスで形成し、固定側摺動部材をチタン基硬質焼結材料で形成しても良い。
【００４３】
【発明の効果】
本発明によって以下の効果を奏する。
【００４４】
１．従来のＴｉＣｘ（ｘ＝１．０）あるいはＴｉＮｙ（ｙ＝１．０）を原料とするチタン基硬質焼結材料と比較して、耐食性を劣化されることなく、耐摩耗性、強度、比強度が改善される。
【００４５】
２．Ｔｉ−（Ｖ，Ｎｂ，Ｔａ）−ＴｉＣ系は高温等の過酷な酸化性酸（たとえば硝酸）に対して特に耐食性が優れるので、核燃料処理プラント等の過酷な条件下でも利用可能である。
【００４６】
３．Ｔｉ−（Ｎｂ，Ｔａ）−ＴｉＣ系は耐高温酸化性も優れるので、発電プラント等の高温腐食ガス雰囲気での使用に特に効果を発揮し、より厳しい条件での使用や長寿命化等の効果がある。
【００４７】
４．化学工業、機械工業等で使用される金型、乾電池合剤成型用金型、ポンプ部品、軸受、メカニカルシール、弁、パイプ、攪拌機、混合機、刃物の耐食・耐摩耗部品として使用した場合、長寿命となり部品交換頻度が減少して、大幅な保守の省力化が達成される。
【００４８】
５．本発明のチタン基硬質焼結材料を使用したすべり軸受は、従来の作業条件よりも過酷な条件に対応でき、本発明の焼結合金を使用することによって作業効率を挙げることができ、とくに、海中ポンプのすべり軸受に適用することによって、長期間の使用に耐えることができる。
【００４９】
６．セラミックスあるいはエンジニアプラスチックで形成されたブッシュの軸方向両端に、内径が等しい部分と外側に向けて内径をテーパー状に拡大する部分とを有する保護ピースを固定することによって、すべり軸受を組み付ける際に、保護ピースが挿入される軸先端部のガイドとして作用し、組み付け作業が容易である。
【図面の簡単な説明】
【図１】本発明に係るチタン基硬質焼結合金を使用したすべり軸受の縦断面構造を示す。
【図２】図１のＡ−Ａ矢視断面図である。
【図３】本発明のすべり軸受を縦軸ポンプの水中軸受として応用した一例を示す。
【図４】比摩耗量の比較を示す。
【符号の説明】
１回転側摺動部材
２固定側摺動部材
１０回転軸
１２本発明軸受スリーブ
１４段差部
１６スリーブキー
１８スリーブ押さえ
２０金属シェル
２２弾性部材
２４ブッシュ
２６保護ピース
２８軸受ケース
３０取付ネジ
３２溝
４０揚水管
４２本発明すべり軸受け[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a titanium-based sintered material with improved wear resistance and sliding characteristics without any loss of corrosion resistance and strength, a method for producing the same, and a plain bearing using the titanium-based sintered material.
[0002]
[Prior art]
The present applicant previously disclosed a titanium-based sintered alloy with improved wear resistance and strength by increasing the hardness without impairing the corrosion resistance and a plain bearing using the same in Patent Document 1.
[0003]
This titanium-based sintered alloy is composed of 5 to 7% by volume of a hard material of TiC or TiN or a solid solution Ti (C, N) thereof, and the balance is Va group, VIa group metal element, Ti, and mutual of them. It consists of a solid solution, a first part made of one or more of the carbides, nitrides and carbonitrides thereof, and a second part made of Ti, and the first part is 1 to 30 volumes. %. This titanium-based sintered alloy has improved wear resistance and strength without deteriorating the corrosion resistance of Ti. As a typical example, the composition of Ti— (Cr, V) —TiC is the same as that of conventional Ti. Since it has higher strength than the Mo-TiC system, it is suitably applied to plain bearings used in harsh environments.
[0004]
[Patent Document 1]
JP-A-6-73486 [0005]
[Problems to be solved by the invention]
In Ti and TiC or TiN used as raw materials in the prior art, when the molar ratio of C and N to Ti in TiC and TiN is expressed as TiCx and TiNy as x and y, x = 1. 0 and y = 1.0. For example, if a Ti-Mo-TiC sintered alloy is taken as an example, during sintering, C in TiC will interdiffuse between the Ti and Mo sides, and finally after sintering, equivalent to TiC 0.5 TiC phase and Ti—Mo alloy phase (β-Ti phase). And, if the coarse Ti raw material powder, for example, containing a large particle size of 45 microns or less, since the C further diffuses and changes from TiC1.0 to TiC0.5, the TiCx phase is accompanied by significant grain growth. And the strength was reduced. Furthermore, if it is going to use fine Ti powder instead of coarse Ti raw material powder, it is very difficult to manufacture because Ti itself is active, and further, the physical properties greatly depend on the amount of dissolved oxygen and the amount of nitrogen. Due to deterioration, industrial application was not possible.
[0006]
When the conventional titanium-based hard sintered material is applied to an underwater slide bearing of a vertical pump used in seawater, replacement has been required in a short period of time due to insufficient corrosion resistance and wear resistance.
[0007]
The problem to be solved by the present invention is to improve the corrosion resistance, wear resistance and strength of the conventional titanium-based hard sintered material, and under severe conditions such as a bearing in seawater for a vertical axis pump for seawater. The present invention provides a titanium-based sintered hard alloy that can also be suitably used for a sliding bearing used in the present invention, a manufacturing method thereof, and a sliding bearing using the titanium-based hard sintered material.
[0008]
[Means for Solving the Problems]
In the titanium-based sintered alloy of the present invention, x or y in TiCx or TiNy is 0.5 to 0.9, which is a numerical value smaller than 1.0. And the balance is Va group metal element, VIa group metal element, Ti, Va group metal element / VIa group metal element / Ti mutual solid solution, and Va group metal element / VIa group metal element / Ti carbide, nitride And one or more of carbonitrides.
[0009]
And after sintering, either one or two of fine TiCx ′ (x ′ = 0.5 to 1.0), TiNy ′ (y ′ = 0.5 to 1.0) or a solid solution of TiC and TiN A sintered body composed of 5 to 95% by volume is formed.
[0010]
In this sintered body, at least 5% by volume is necessary for improving the wear resistance, and 95% by volume is required for maintaining the strength and sliding characteristics necessary for a member such as a slide bearing. It is necessary to maintain below.
[0011]
In the present invention, a coarse Ti raw material with grain growth that reduces hardness and strength by using TiCx or TiNy powder in which x and y are 0.5 to 0.9 as raw materials in advance. The amount of powder can be minimized or eliminated.
[0012]
Also, since C and N are interstitial atoms, the diffusion rate is much faster than that of the Va group, VIa group metal elements and Ti, and the diffusion rate increases from a lower temperature, so the sinterability is remarkably improved. , Densification is possible at lower temperatures. Further, TiCx or TiNy powders each having x and y of 0.5 to 0.9 can be easily obtained as fine powders, and further improve the sinterability. Can improve body hardness and strength.
[0013]
Furthermore, when component elements that are solid-solved in the Ti phase are added in the form of carbides, nitrides, carbonitrides, decomposition reactions of carbides and the like occur in parallel during the sintering densification process, and then solid solution occurs. This decomposition / solid solution reaction takes time. As a result, the concentration of these solutes in Ti is unlikely to increase, a suitable composition can be controlled, and physical properties can be improved.
[0014]
This titanium-based hard sintered alloy according to the present invention is extremely excellent in wear resistance and corrosion resistance, and in the chemical and mechanical industries, molds, pump parts, bearings, mechanical seals, valves, pipes, agitators, It can be suitably used for mixers, blades and the like.
[0015]
In particular, when the titanium-based hard sintered alloy according to the present invention is applied to a slide bearing, one sliding member is formed of the titanium-based sintered alloy according to the present invention, and the other sliding member is ceramic or engineer plastic. By forming the slide bearing in this way, a slide bearing having excellent wear resistance and excellent corrosion resistance can be obtained even when immersed in seawater.
[0016]
The titanium-based hard sintered alloy according to the present invention is a sliding bearing comprising a rotating sliding member and a fixed sliding member used under severe conditions, particularly in a seawater bearing of a vertical axis pump for seawater. In the case of use in the present invention, the titanium-based hard sintered alloy according to the present invention is applied to either the rotating sliding member or the stationary sliding member, and the other member is mainly composed of silicon nitride or silicon carbide. Ceramics, PTFE (tetrafluoroethylene resin), or PEEK (polyether ether ketone resin) can be the main component.
[0017]
When the titanium-based hard sintered material of the present invention is used as the rotary sliding member, the bearing sleeve formed of the titanium-based hard sintered material of the present invention is fitted and fixed to the rotating shaft, and the fixed-side sliding member is A bush made of engineer plastic mainly composed of silicon nitride or silicon carbide, or PTFE (polytetrafluoroethylene resin) or PEEK (polyether ether ketone resin), and the bush A cylindrical elastic member that is long in the axial direction is closely fixed to the inner peripheral surface of the cylindrical elastic member, and the elastic member is closely fixed to the inner peripheral surface of the cylindrical metal shell. A cylindrical protective piece having a taper-shaped portion is fixed to both ends of the bush in the axial direction on the inner peripheral surface of the elastic member, and the metal shell is pivoted. It can be those fixed to the case. In this case, this protective piece acts as a guide when inserting the shaft in which the rotation side sliding member is inserted and fixed in the bush, the shaft tip directly contacts the end of the bush, and the edge of the bush is missing. Etc. can be prevented.
[0018]
Such a sliding bearing has an extremely stable sliding characteristic even under non-lubricated conditions, that is, when it is slid in the atmosphere, and further under conditions where lubrication under a fluid such as seawater is performed. Excellent sliding characteristics. Furthermore, even when used in water mixed with solids such as silica sand and alumina fine particles, it has excellent wear resistance. Therefore, it is suitable as an underwater bearing such as a vertical axis pump that handles seawater mixed with hard solids such as sand.
[0019]
Especially when the slurry concentration is high and wear resistance is required, ceramics are used for one sliding member, the dry operation time is long, and sliding characteristics under both solid and fluid lubrication conditions are required. If engineer plastic is used, the features of the present invention can be utilized more effectively.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on examples.
[0021]
Example 1
This example is an example showing the characteristics of the titanium-based hard sintered material itself according to the present invention.
[0022]
After mixing commercially available TiCx (X = 0.5 to 0.9) and / or TiNy (Y = 0.5 to 0.9), Ti, Mo, W powder, etc. at a predetermined ratio, 1 The mixture was mixed for a time and press-molded at 2000 kgf / cm ² . This was sintered at 1250 to 1500 ° C. in a vacuum atmosphere for 2 hours. The composition was changed as shown in Table 1. The obtained sintered body was examined for hardness (HRC) and strength (three-point bending strength / GPa) and corrosion resistance. Corrosion resistance was evaluated by evaluating the corrosion rate by dipping in a dry battery mixture (25 ° C.) for 7 days under open air, and the results were: ○: 0.05 mm / year or less, Δ: 0.1 mm / year or less, ×: 0 It is shown in Table 2 as exceeding 1 mm / year.
[0023]
[Table 1]

[Table 2]

Examples 1-4 of the present invention are higher in hardness and strength and comparable in corrosion resistance to comparable alloys 21 to 24 using conventional TiC1.0 and / or TiN1.0 raw material powders. From this, it can be seen that it is excellent in corrosion resistance and wear resistance.
[0024]
Examples 5 to 6 of the present invention are superior in corrosion resistance and abrasion resistance because they are higher in hardness and strength and have the same or higher corrosion resistance than the comparative alloy 25 using conventional TiC 1.0 raw material powder. You can see that Compared with Ti (JIS type 2) of the comparative alloy 26 shown as a comparative example, the hardness is extremely high, so that the wear resistance is excellent. Similarly, compared with the WC-1.0 mass% Cr-8Ni cemented carbide of the comparative alloy 27, it is remarkably excellent in corrosion resistance.
[0025]
From the above, it is clear that the present invention is comprehensively superior to the comparative example.
[0026]
Example 2
Table 3 shows the compositions and sintering temperatures of Alloys 11 to 18 of the present invention containing one or more of carbides, nitrides, carbonitrides of the periodic table Va and VIa group metal elements and their solid solutions. 4 shows the characteristics such as hardness, strength, and corrosion resistance, and the overall judgment result.
[0027]
[Table 3]

[Table 4]

It is obvious that the alloys of the present invention 11 to 18 are superior to the comparative alloys 21 to 27 in that they are excellent in wear resistance and have both strength and corrosion resistance, and thus are comprehensively excellent.
[0028]
The alloy of the present invention exhibits excellent corrosion resistance against neutrality and acidity (non-oxidizing acid: hydrochloric acid / sulfuric acid, etc., oxidizing acid: nitric acid, etc.). In particular, the alloys 1 and 11 to 14 of the present invention are alloys containing any of the three elements of V, Nb, and Ta, which are more excellent than the other alloys of the present invention with respect to oxidizing acids. Corrosion resistance was shown. That is, the alloy of the present invention containing any one of these three elements V, Nb, and Ta has particularly good corrosion resistance against an oxidizing acid.
[0029]
Further, when an oxidation increase test (in the atmosphere) at 900 ° C. for 1 hour was performed, the alloys 1 and 11 to 13 of the present invention containing Nb and Ta had Nb and Ta of course compared to the comparative alloys 21 to 27. The present invention alloys 2-6 and 14-18, which do not contain, exhibited 2 to 9 times better oxidation resistance than the present alloys. That is, the alloy of the present invention containing Nb · Ta has particularly good high-temperature oxidation resistance.
[0030]
Example 3
This embodiment shows an example in which the titanium-based hard sintered alloy according to the present invention is applied to a slide bearing as an underwater bearing of a vertical axis pump for seawater.
[0031]
FIG. 1 is a view showing a longitudinal sectional structure of a slide bearing using a titanium-based hard sintered alloy according to the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG.
[0032]
In these drawings, 1 indicates a rotation side sliding member, and 2 indicates a stationary side sliding member.
[0033]
A cylindrical bearing sleeve 12 formed of a titanium-based hard sintered alloy shown in Example 1 is fitted into the rotating shaft 10 of the rotating side sliding member 1. The axial position of the bearing sleeve 12 is regulated by the step portion 14 provided on the rotary shaft 10, the relative rotation around the axis is regulated by the sleeve key 16, and further, the sleeve presser 18 is prevented from coming off in the axial direction. It is regulated and is fitted and fixed to the rotary shaft 10.
[0034]
The fixed-side sliding member 2 has a cylindrical elastic member 22 made of hard rubber or the like closely attached to the inner peripheral surface of the cylindrical metal shell 20 and is firmly bonded and fixed appropriately. A cylindrical bush 24 having an axial length shorter than that of the elastic member 22 is closely fitted on the inner peripheral surface of the elastic member 22. The bush 24 is made of ceramics whose main component is silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ), or engineer plastics whose main component is PTFE or PEEK. Further, cylindrical

protective pieces

26 and 26 made of a plastic material such as PTFE are fixed to both ends in the axial direction of the bush 24 on the inner peripheral surface of the elastic member 22. These

protective pieces

26, 26 have a portion having the same inner diameter as the bush 24 and a portion that increases the inner diameter in a tapered shape toward the outside. The assembly material of the metal shell 20, the elastic member 22, the bush 24, and the

protection pieces

26 and 26 is fitted and inserted into the bearing case 28, and positioning and fixing are further performed by the mounting

screws

30 and 30. A plurality of

grooves

32 and 32 are provided in the axial direction on the inner peripheral surface of the bush 24.
[0035]
FIG. 3 shows an example in which the above-described sliding bearing of the present invention is applied as a submerged bearing of a vertical axis pump. In the figure, a rotating shaft 10 that is driven to rotate by a motor (not shown) is disposed at an axial center position in the pumping pipe 40, and an appropriate intermediate portion of the rotating shaft 10 is supported by the sliding bearings 42 and 42 of the present invention. 40 is rotatably supported.
[0036]
In such a structure, as shown in FIG. 1, when the rotating shaft 10 with the bearing sleeve 12 or the like assembled is inserted into the bush 24 assembled with the bearing case 28, the tapered portion of the protective piece 26 and the portion with the same inner diameter are formed. It acts as a guide, and the tip of the rotating shaft 10 does not come into direct contact with the end of the bush 24. For this reason, the relatively fragile bush 24 formed of ceramics or engineer plastic can prevent breakage such as chipping of the rotating shaft 10 during assembling work. As a result, the assembly work is easy.
[0037]
If the sliding bearing of the present invention is applied as a submersible bearing of a vertical pump as shown in FIG. 3, the lubricating water is used in comparison with a device that requires lubricating water when starting a rubber bearing or the like as a submerged bearing. Equipment for supply and shaft protection pipes are unnecessary, and the entire pump equipment can be greatly simplified.
[0038]
Next, in order to investigate the corrosion resistance of the sliding bearing of the present invention as this underwater bearing, the following experiment was conducted. A sliding bearing in which the rotating side sliding member is formed of the titanium-based hard sintered material of the present invention and the comparative alloy 23 which is a conventional material, and the stationary side sliding member is formed of two types of ceramics (SiC and Si ₃ N ₄ ). Then, the specific wear amount was compared. The experimental conditions are a bearing surface pressure of 1 kgf / cm ² (9.8 N / cm ² ), a peripheral speed of 4.7 m / s, a seawater + sand mixture (sand concentration of 2000 ppm), and an experimental time of 100 hours.
[0039]
The measurement results are shown in FIG. As is apparent from the figure, when the fixed-side sliding member is made of ceramic, the titanium-based hard sintered material and the ceramic of the present invention are compared with the conventional plain bearing made of a combination of the comparative alloy 23 and the ceramic. The specific wear of the plain bearing made of the combination was about 1/4 or less.
[0040]
On the other hand, when the fixed-side sliding member is an engineer plastic mainly composed of PTFE resin, the titanium-based hard sintered material of the present invention is compared with a plain bearing made of a combination with the conventional comparative alloy 23. The specific wear of the plain bearing made of a combination of engineer plastics composed mainly of PTFE resin was about 1/5 or less. The wear amount of engineer plastic was higher than that of titanium-based hard sintered material because of the hardness.
[0041]
As a result, the sliding bearing of the present invention in which one sliding member is formed of a titanium-based hard sintered alloy and the other sliding member is formed of ceramics has excellent corrosion resistance against seawater and excellent wear resistance. It was confirmed that
[0042]
In the above embodiment, an example in which the sliding bearing of the present invention is applied as a submerged bearing of a vertical axis pump is shown, but the application is not limited to this, and a sliding bearing used in liquid or gas, The present invention may be applied to any of plain bearings used for general rotating machines, plain bearings used under non-lubricating conditions, and the like. Further, the rotation side sliding member may be formed of ceramics, and the stationary side sliding member may be formed of a titanium-based hard sintered material.
[0043]
【The invention's effect】
The present invention has the following effects.
[0044]
1. Compared to conventional titanium-based hard sintered materials using TiCx (x = 1.0) or TiNy (y = 1.0) as a raw material, wear resistance, strength and specific strength are not degraded. Is improved.
[0045]
2. The Ti— (V, Nb, Ta) —TiC system is particularly excellent in corrosion resistance against harsh oxidizing acids (for example, nitric acid) such as high temperatures, and therefore can be used under harsh conditions such as nuclear fuel processing plants.
[0046]
3. The Ti- (Nb, Ta) -TiC system is also excellent in high-temperature oxidation resistance, so it is particularly effective for use in high-temperature corrosive gas atmospheres such as power plants, and has effects such as use under more severe conditions and longer life. There is.
[0047]
4). When used as a mold used in the chemical industry, machine industry, etc., mold for dry cell mixture molding, pump parts, bearings, mechanical seals, valves, pipes, agitators, mixers, anti-corrosion and wear-resistant parts of blades, The service life is extended, the frequency of parts replacement is reduced, and significant labor savings are achieved.
[0048]
5. The plain bearing using the titanium-based hard sintered material of the present invention can cope with conditions more severe than the conventional working conditions, and can increase the working efficiency by using the sintered alloy of the present invention. By applying to submerged pump slide bearings, it can withstand long-term use.
[0049]
6). When assembling a plain bearing by fixing a protective piece having a portion having an equal inner diameter and a portion having an inner diameter tapered toward the outside at both ends in the axial direction of the bush formed of ceramics or engineer plastic, It acts as a guide for the shaft tip where the protective piece is inserted, and the assembly work is easy.
[Brief description of the drawings]
FIG. 1 shows a longitudinal sectional structure of a slide bearing using a titanium-based hard sintered alloy according to the present invention.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
FIG. 3 shows an example in which the slide bearing of the present invention is applied as a submersible bearing of a vertical axis pump.
FIG. 4 shows a comparison of specific wear amounts.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotating side sliding member 2 Fixed side sliding member 10 Rotating shaft 12 Bearing shaft 14 of the present invention Stepped portion 16 Sleeve key 18 Sleeve pressing 20 Metal shell 22 Elastic member 24 Bushing 26 Protective piece 28 Bearing case 30 Mounting screw 32 Groove 40 Pumping Tube 42 of the present invention slide bearing

Claims

TiCx (x = 0.5-0.9) and / or TiNy (y = 0.5-0.9) powder,
A raw material composed of Ti, a Va group metal element, a VIa group metal element, and one or two or more powders in a mutual solid solution composed of two or more of Ti, a Va group metal element, and a VIa group metal element. Any one of TiCx ′ (x ′ = 0.5 to 1.0), TiNy ′ (y ′ = 0.5 to 1.0) obtained by sintering, and a solid solution of TiC and TiN Or two to more than 5 to 95% by volume, and the balance is a mutual solution consisting of two or more of Va group metal element, VIa group metal element, Ti, Va group metal element, VIa group metal element and Ti, And a titanium-based hard sintered material comprising at least one of carbides, nitrides and carbonitrides of group Va metal elements, group VIa metal elements and Ti.

At least a part of one or two or more kinds of powders of the group Va metal element, the group VIa metal element, or the mutual solid solution of the group Va metal element and the group VIa metal element in the raw material are carbide, nitride, and The titanium-based hard sintered material according to claim 1, which is one or more of carbonitrides.

Any one or two or more of TiCx ′ (x ′ = 0.5 to 1.0), TiNy ′ (y ′ = 0.5 to 1.0) and a solid solution of TiC and TiN is used in an amount of 5 to 95. Volume% and the balance are Va group metal element, VIa group metal element, Ti, mutual solid solution composed of two or more of group Va metal element, group VIa metal element and Ti, and group Va metal element and group VIa A method for producing a titanium-based hard sintered material comprising one or more of metal elements and Ti among one or more of carbides, nitrides and carbonitrides,
TiCx (x = 0.5-0.9) and / or TiNy (y = 0.5-0.9) powder;
Ti, Va group metal element, VIa group metal element, Va group metal element, VIa group metal element and mutual solid solution composed of two or more of Ti, and Va group metal element, VIa group metal element and Ti One or more kinds of carbides, nitrides and carbonitrides are mixed with one or more powders, mixed, molded, and then sintered at 1250 to 1500 ° C. in a vacuum atmosphere. Manufacturing method.

In the sliding bearing comprising the rotary sliding member and the fixed side sliding member, any one member is made of the titanium-based hard sintered material according to claim 1 or claim 2,
The other member is a titanium-based hard-fired ceramic consisting of ceramics whose main component is silicon nitride or silicon carbide, or engineer plastics whose main component is PTFE (tetrafluoroethylene resin) or PEEK (polyetheretherketone resin). A plain bearing using a binder.

In the slide bearing comprising the rotary sliding member and the fixed side sliding member, the rotary sliding member is made of the titanium-based hard sintered material according to claim 1 or claim 2,
A bearing sleeve formed of a titanium-based hard sintered material is fitted and fixed to the rotating shaft,
The fixed-side sliding member is made of ceramics whose main component is silicon nitride or silicon carbide, or engineer plastic whose main component is PTFE (tetrafluoroethylene resin) or PEEK (polyether ether ketone resin). A bush, and the bush is closely fixed to the inner peripheral surface of a cylindrical elastic member that is long in the axial direction, the elastic member is closely fixed to the inner peripheral surface of the cylindrical metal shell, and the inner diameter is equal to the bush. A cylindrical protective piece having an inner diameter tapered toward the outside is fixed to both ends in the axial direction of the bush on the inner peripheral surface of the elastic member, and the metal shell is fixed to the bearing case. A plain bearing using a titanium-based hard sintered material.