JP3909658B2

JP3909658B2 - Vanadium-based coating film forming method and vanadium-based coating-treated inorganic product

Info

Publication number: JP3909658B2
Application number: JP2001182363A
Authority: JP
Inventors: 稔篠田; 清彦渡部
Original assignee: Yuken Industry Co Ltd
Current assignee: Yuken Industry Co Ltd
Priority date: 2001-06-15
Filing date: 2001-06-15
Publication date: 2007-04-25
Anticipated expiration: 2021-06-15
Also published as: JP2002371352A

Description

【０００１】
【技術分野】
本発明は、バナジウム系被膜を無機基材の表面に成膜する方法に関する。特に、鍛造やプレス成形等の金属塑性加工用金型に好適な被膜の形成方法に関する。
【０００２】
【背景技術】
従来、プレス成形等の金型は、基材が一般に鋼製であるため、耐摩耗性等の耐久性を維持するために、硬質被膜処理をする必要がある。
【０００３】
そして、硬質被膜処理のひとつとして炭化バナジウム（ＶＣ）膜処理がある。そして、ＶＣ膜の形成方法は、熱反応析出拡散法（ＴＲＤ法：Thermal ReactiveDeposition and Diffusion）が主流であった（特開昭４９−１１８６３７号・特公昭５４−７６１０号・特公昭５６−１８６７０号公報等参照）。
【０００４】
しかし、上記ＴＲＤ法の場合、浴温を８００〜１２００℃（前記公報参照）とする必要があり、作業環境、省エネルギー、生産性等の見地から望ましくなかった。すなわち、作業環境が高温となり、浴温を維持するためのエネルギーが必要となるとともに、被膜処理後の製品の冷却にも時間を要した。
【０００５】
また、母材（基材）が鋼である金型の場合、鋼の焼き戻し温度（通常、５５０〜６５０℃：「半導体・金属材料用語辞典」工業調査会、１９９９参照）よりはるかに高い温度に母材がさらされる。このため、金属塑性加工用金型のような高い寸法精度が要求される鋼製品の場合不適であった。
【０００６】
【発明の開示】
本発明は、上記にかんがみて、鋼の焼き戻し温度より低い成膜温度でも熱反応析出拡散法（溶融塩拡散法）によるのと同等の硬度とともに、実用密着性および靱性を備えたバナジウム系被膜を形成可能なバナジウム系被膜の成膜方法を提供することを目的（課題）とする。
【０００７】
上記課題を解決するために、鋭意開発に努力をする過程で、従来、硬度の低いバナジウム系被膜しか実用的な密着性や靱性が得られないとされていたイオンプレーティングにより鋼材等の表面に反応成膜させる場合において、注入ガス量／ガス比を膜種に対応させて調節・維持することにより上記課題を解決できることを見出して、下記構成のバナジウム系被膜の成膜方法に想到した。
【０００８】
バナジウム系被膜をイオンプレーティングにより無機基材の表面に反応成膜させる方法において、
前記バナジウム系被膜が、基材側から順に配されたＶＮ膜、ＶＣＮ膜及びＶＣ膜からなる複合被膜であって、
バナジウムを蒸発源とし、注入ガスを窒素ガス及び／又は炭化水素ガスとして注入ガス量・ガス比を膜種に対応させて調節維持することにより、前記バナジウム系被膜の各層をそれぞれ反応成膜させることを特徴とする。
【０００９】
上記の如く、ガス注入量ないしガス比を調節することにより、成膜組成を無機基材に対して密着性の良好な（通常硬度が低い）組成から耐摩耗性の良好な（通常硬度が高い）組成へと段階的にないし連続的に変化させることができる。そして、イオンプレーティングの成膜温度（基板温度）は、通常５５０℃が上限である。
【００１１】
そして、硬度が、ＶＮ：ＨＶ２０００、ＶＣＮ：ＨＶ２５００、ＶＣ：ＨＶ３５００と順に高くなっており、成膜組成を無機基材に対して密着性の良好な（通常硬度が低い）組成から耐摩耗性の良好な（通常硬度が高い）組成へと段階的にないし連続的に変化させることができる。
【００１２】
さらに、各層の反応成膜工程間の移行に際して、注入ガス量・ガス比を段階的又は連続的に変化させて各傾斜組成の層間結合層を反応成膜させることが望ましい。各層間の組成変化の落差（ギャップ）が縮小されて、熱衝撃や機械的衝撃を受けた場合の層間剥離がより発生し難くなるためである。
【００１３】
さらに、無機基材として鋼材を用いた場合、成膜時の基板温度を４００〜５００℃に調節することが望ましい。
【００１４】
強靭鋼材の焼き戻し温度が、前述の如く、通常、約５５０〜６５０℃であるため、温度バラツキを考慮した場合、５００℃以下が望ましく、逆に４００℃未満であると、各成膜の密着性を得難くなる。
【００１５】
上記イオンプレーティングによりバナジウム系被膜を反応成膜させたバナジウム系被膜処理無機製品は、下記構成のものとなる。
【００１６】
バナジウム系被膜を無機基材の表面に備えた無機製品において、
前記バナジウム系被膜が、基材側から順に配されたＶＮ膜、ＶＣＮ膜及びＶＣ膜からなる複合被膜であることを特徴とする。
【００１７】
さらには、前記複合被膜の各層間に、傾斜組成の層間結合層を介在させることが望ましい。
【００１８】
そして、複合被膜の最外層硬度をビッカース硬度：ＨＶ３０００以上とすることが耐摩耗性の見地から望ましく、当該硬度は、膜厚比を、ＶＮ膜／ＶＣＮ膜／ＶＣ膜＝０．５／０．５／９〜３／３／４とし、合計膜厚２〜５０μｍとすることにより得易くなる。
【００１９】
また、無機基材としては、通常、強靭鋼材を使用し、製品としては機械的衝撃や熱衝撃にさらされ易く、寸法精度も要求される金属塑性加工用金型に適用すると、本発明の効果がさらに顕著となる。
【００２０】
なお、特開平９−７１８５６号公報に、バナジウム系被膜（ＶＣ＋４０％Ｎｉ）をＡＩＰ法により形成する技術が記載されているが、本発明の如く、硬度の高い（ＨＶ２０００以上、望ましくはＨＶ３０００以上）バナジウム系被膜を予定していない。
【００２１】
【発明を実施するための最良の形態】
以下、本発明を実施形態に基づいて、詳細に説明をする。本明細書で、化学式ＶＮ、ＶＣＮ、ＶＣは、それぞれ窒化バナジウム（立方晶系）、炭窒化バナジウム（同）、炭化バナジウム（同）を意味する。
【００２２】
また、「ＨＶ」は、JIS Z 2244に準じて測定したビッカース硬さを意味する。
【００２３】
図１は、本発明の一実施形態のバナジウム系被膜処理無機製品の部分断面図であり、基本的には、鋼材製の基材１２の表面に基材１２側から順に配されたＶＮ膜１４、ＶＣＮ膜１６、ＶＣ膜１８からなる複合被膜（バナジウム系被膜）を備えた無機製品である。
【００２４】
上記において、基材１２側から順にＶＮ膜１４、ＶＣＮ膜１６、ＶＣ膜１８と配すると、前述の如く、その順に硬度が高くなり、基材、特に鋼材製基材（通常、ＨＶ６００〜９００）との硬度差を小さくすることができる。したがって、表面硬度が高くても基材との密着性を確保し易くなる。そして、ＶＣ膜１８は、前述の如く、ＨＶ３５００であり、耐摩耗性確保の要因（パラメータ）となる表面硬度を確保しやすい。なお、さらに耐摩耗性の向上が要求される場合は、耐摩耗性の他の要因である摩擦係数（動摩擦係数：JIS K 7125）を低減させることが望ましい。その動摩擦係数（μ）は、０．３以下、望ましくは，０．２以下とする。当該摩擦係数は、後述の如く、炭化水素（炭素供給源）の量を増大させることにより容易に得ることができる。
【００２５】
本実施形態では、必然的ではないが、さらに、複合被膜の各層間、すなわちＶＮ膜１４／ＶＣＮ膜１６間およびＶＣＮ膜１６／ＶＣ膜１８間に、傾斜組成の第一・第二層間結合層２０、２２を介在させてある。
【００２６】
これらの層間結合層２０、２２の存在により、各層間の硬度差がさらに縮まり、結果的に機械的衝撃や熱衝撃による層間剥離が発生し難くなり、結果的にバナジウム系被膜の靱性が増大する、すなわち、耐久性が増大する。
【００２７】
より具体的には、各膜層の膜厚比を、ＶＮ膜１４／ＶＣＮ膜１６／ＶＣ膜１８＝０．５／０．５／９〜３／３／４、望ましくは、１／１／８〜２．５／２．５／５、最も望ましくは、約２／２／６とし、合計膜厚２〜５０μｍ、望ましくは３〜１０μm、最も望ましくは約６μｍとする。
【００２８】
当該ＶＣ膜のＶＮ膜またはＶＣＮ膜に対する膜厚比が大きすぎると、ＶＣ膜の膜厚が特に１０μｍを越えるような場合、膜の圧縮応力が増大するために、ＶＣ膜が自己破壊若しくは下層（ＶＣＮ膜）との層間剥離が発生し易い。また、膜靱性が低くなるため、鍛造時の衝撃により、ＶＣ膜に亀裂が発生し易くなる。
【００２９】
逆にＶＣ膜のＶＮ膜またはＶＣＮ膜に対する膜厚比が小さすぎると、被膜全体の硬度がＨＶ３３００以下となって、耐摩耗性を得難くなる。
【００３０】
また、複合被膜の合計膜厚が小さすぎると、所要の表面硬さ（耐摩耗性）を得難く、逆に大きすぎると、バナジウム系被膜の基材からの層剥離が発生し易くなる。また、膜靱性が低下するためプレス・鍛造時の衝撃により被膜に亀裂が発生し易くなる。
【００３１】
また、層間結合層２０、２２の層厚（膜厚）は、バナジウム系被膜の構成層であるＶＮ膜、ＶＣＮ膜、ＶＣ膜に比べて、格段に薄いものである。層間結合の作用を奏すれば、可及的に薄い方が望ましく、通常、ＶＮ膜、ＶＣＮ膜の０．５／１０〜３／１０、望ましくは、１／１０〜２／１０、最も望ましくは約１．５／１０とする。設定理由は、下記の如くであると推定される。
【００３２】
基材と被膜との硬度格差による剥離を抑制するために三層構造とするだけで充分と考えられる。また、層間結合層が無くても被膜層間の硬度格差はＨＶ１０００以内であるため、使用目的に対して上記設定以上の厚さは必要ないと考えられる。
【００３３】
ここで、強靭鋼材を使用するのは、金属塑性加工用金型の如く、機械的衝撃、熱衝撃を受け易い金属塑性加工用金型等の金属製品（無機製品）を予定しているためである。
【００３４】
鋼材としては、高速度鋼、ダイス鋼、粉末ハイス鋼、セミハイス鋼等のＦｅ基合金（強靭鋼材）を好適に使用できる。基材としては、５５０℃以上の耐熱性を有すれば、Ｆｅ基合金に限られず、Ｔｉ基合金、銅基合金、サーメットさらにはセラミックス等が使用可能である。ただし、Ｆｅ基合金、特に、強靭鋼以外は、焼き戻しによる寸法歪が発生しないため、本発明の効果の全てを享受できない。
【００３５】
上記Ｆｅ基合金の具体例としては、ＳＫＨ５１、ＳＫＨ５５、ＳＫＨ５７等の高速度鋼、ＳＫＤ１１、ＳＫＤ６１等の冷間・熱間ダイス鋼、さらには、ＨＡＰ１０、ＨＡＰ４０等の粉末ハイス鋼（日立金属社製）、ＹＸＲ３、ＹＸＲ７、ＹＸＲ３３等のセミハイス鋼（同社製）等を挙げることができる。
【００３６】
次に、上記実施形態の無機製品の製造方法、すなわち、バナジウム被膜の成膜方法について説明をする。
【００３７】
本実施形態では、図２に示すようなイオンプレーティング装置、通常、アークイオンプレーティング（ＡＩＰ）装置を用いて行う。ＡＩＰ法は、バナジウムを蒸発源とし、反応ガスを窒素ガス及び／又は炭化水素ガスとして注入ガス量・ガス比を膜種・膜厚に対応させて調節維持することにより、ＶＮ膜、ＶＣＮ膜、ＶＣ膜を高純度で基材上に反応成膜させることが容易なためである。当然、多陰極熱電子照射法、高周波励起法、ホロカソードディスチャージ法、クラスタ法、活性化反応蒸着法、等他のタイプのイオンプレーティング法も可能である。
【００３８】
イオンプレーティング装置は、チャンバー２４内に、バナジウム金属を保持する蒸発源保持部（ポット部）２５と、バイアス電圧源２６と接続された被処理物（基材）２８を載置する回転テーブル３０を備えている。さらに、チャンバー２４は、チャンバー内を所定真空度に維持する排気ポンプと接続される排気口３２と、反応ガス（窒素及び／又はメタン）を導入する反応ガス導入口３４とを備えるとともに、チャンバー２４内を所定温度に維持するとともに基材（基板）２８も所定温度に維持するヒータ３６を備えている。
【００３９】
そして、ＡＩＰ法により反応成膜する場合を例に採り説明する。
【００４０】
蒸発源とするバナジウム（Ｖ）は、通常、ツウナインからスリーナインの純度のものを使用する。また、バナジウムと反応する元素である窒素及び炭素の供給源であるガスは、前者は窒素ガス（Ｎ₂）、後者としてメタン（ＣＨ₄）、エタン、エチレン、アセチレン等の炭化水素ガスを使用可能である。炭化水素ガスとしては、未反応性ガスが装置や基材表面を汚染するため、煤の発生し難い、メタンが望ましい。そして、それらの純度は、それぞれ、スリーナインからシックスナインとする。
【００４１】
そして、ＡＩＰ法による成膜条件は、表１の通りとする。
【００４２】
【表１】

【００４３】
上記条件項目の着眼点について以下にそれぞれ説明する。
【００４４】
▲１▼真空度：
真空度が高すぎる（絶対圧が低い）と、反応ガス量が少ない状態となり、成膜速度が遅くなり生産性が低下し、また、成膜された被膜が、金属成分過多の組成になってしまったり、粒子が粗くて空隙の多いもの（結晶核の生成が遅くなるためと推定される。）になりやすい。
【００４５】
逆に真空度が低すぎる（絶対圧が高い）と、反応ガス量が過剰となり、反応に使用されずに充分に活性化されていないガスが、成長被膜面で吸着インヒビタ（抑制剤）として作用するおそれがある。
【００４６】
特に、金型に本発明を適用して耐摩耗性の向上を期待する場合、表面膜（ＶＣ膜）は、膜硬度とともに滑り性も要求され、そのような場合には、潤滑剤として作用するＣ（カーボン）を膜中に含有させることが望ましい。しかし、Ｃ含有率が過剰になると膜硬度が低下して、やはり耐摩耗性が低下する。そのようなバランスが採れる真空度は、約２５〜３５mtorr（33.3〜46.6Ｐａ）、望ましくは約３０mtorr（39.9Ｐａ）、メタンガス量で、約４００〜６００mL/min、望ましくは約５００mL/minとする。
【００４７】
▲２▼アーク電流：
電流値が低すぎると成膜速度が遅くなり、逆に高過ぎると、装置の安全性の見地から望ましくない。
【００４８】
▲３▼バイアス電圧：
一般的に、バイアス電圧が高いほど成膜速度が遅くなるため、生産性を考慮して適当な範囲で設定する。供給ガスが窒素（Ｎ₂）の場合、バイアス電圧の窒化物成膜結晶にほとんど影響はなく５０〜４００Ｖ、望ましくは、５０〜２００Ｖの範囲で適宜設定できる。ＣＨ₄等の炭化水素の場合、バイアス電圧が低いと、ＶＣの結晶性が低くなって、炭化物成膜の耐摩耗性が得難くなる。このため、窒素と同様、５０〜４００Ｖの範囲でも可能であるが、生産性と結晶性とのバランスから、約１００〜２００Ｖが望ましく、さらに望ましくは約１５０Ｖとする。
【００４９】
▲４▼基板温度：
温度が高いほど成膜速度が速くて望ましいが、省エネルギー及び基材の耐熱性の見地から、基材が鋼の場合、焼き戻しによる寸法歪が発生しない温度以下、通常３５０〜５５０℃、望ましくは４００〜５００℃とする。なお、基材がセラミックスの如く、熱歪が発生しない場合は、イオンプレーティングの最高温度５５０℃前後で行ってもよい。
【００５０】
また、各層間に層間結合層を形成する場合におけるガス流量及び着膜時間の一例を表２に示す。表２において、Ｘはバナジウム充填量および膜厚により異なるが、例えば、充填量８００ｇで合計膜厚３〜１０μｍの場合、Ｘ＝３００〜１０００秒とする。
【００５１】
【表２】

【００５２】
表２の各層間結合層のガス量及び圧力は、瞬時にその量及び圧力になるわけでなく、通常、着膜時間の中間時間、例えば４０〜５０秒後にその圧力に連続的に上昇して、その後設定値を維持するものである。その点は、ＶＣＮ膜、ＶＣ膜でも同様である。
【００５３】
なお、上記では、バナジウム系被膜として、ＶＮ膜／ＶＣＮ膜／ＶＣ膜の複合被膜を例にとって説明したが、ＶＮ膜、ＶＣＮ膜及びＶＣ膜の各単層膜でも、さらには、ＶＮ膜／ＶＣＮ膜、ＶＣＮ膜／ＶＣ膜、ＶＮ膜／ＶＣ膜の各複合膜についても同様にして成膜できる。鋼を基材とし、複合膜とする場合は、原則的には硬度の低い方を基材側とし、各層間には、層間結合層を形成するようにすることが望ましい。
【００５４】
したがって、本発明の成膜方法は、一番硬度の低いＶＮ膜でも硬度はＨＶ２０００であり、ＨＶ３０００以上の硬度のバナジウム系被膜を容易に鋼等の基材上に密着性良好に成膜できる。
【００５５】
また、本発明のバナジウム系被膜の成膜方法は、金属塑性加工用金型ばかりでなく、耐摩耗性が要求されるあらゆる無機製品、例えば、シリンダライナー、バルブリフター、スプロケット、ギヤ、プーリー、車軸等の輸送機関関連部材、機械部品、治具等に適用できるものである。
【００５６】
【試験例】
次に、本発明の効果を確認するために実施例１・２・３および比較例１・２について行った試験例を説明する。
【００５７】
なお、イオンプレーティング装置は、神戸製鋼社製「ＡＩＰ４０２４型」を用い、Ｖは純度スリーナインのもの８００ｇを充填し、Ｎ₂は純度ファイブナイン、ＣＨ₄は純度スリーナインのものをそれぞれ使用した。
【００５８】
実施例１：表２において、Ｘ＝６００ｓとしてバナジウム系被膜を基材である金型のプレス面に合計膜厚約6μｍのバナジウム系被膜（ＶＮ膜／ＶＣＮ膜／ＶＣ膜）を成膜した。また、基材は冷間ダイス鋼（ＳＫＤ１１：ＨＶ６５０、ＨＲＣ58.0靱性評価と同じ）製のプレス加工用金型（図３：１５０ｍｍφ×７０mmｔ）とした。
【００５９】
実施例２：実施例１において、設定圧力を２０mtorr（26.6Ｐａ）としたものである。他の条件は、実施例１と同じ。
【００６０】
実施例３：実施例１において、Ｘ＝３０００ｓとして膜厚約6μｍの単層ＶＣ膜を成膜した。他の条件は、実施例１と同じ。
【００６１】
比較例１・２は、下記に準じて、熱ＣＶＤ法及びＴＲＤ法に基づいて、膜厚それぞれ約6μｍの単層ＶＣ膜及び単層ＴｉＣ膜を、実施例１と同じ基材（ＳＫＤ１１製プレス成形用金型）上に成膜（成膜温度：約１０００℃）した。
【００６２】
そして、上記で得た各実施例及び比較例の金型について、下記項目の試験を行った。
【００６３】
（１）耐久性評価試験
実施例１及び比較例１について、ワーク材（SUS、３mmｔ）を用いて、不良品が発生するまでの型寿命（摩耗による成形不良）の成形個数を評価した。
【００６４】
実施例１の型寿命は６万個であったのに対し、比較例１は約４万個であった。
【００６５】
なお、このとき型の寸法歪を測定したが、実施例１は最大でも±４０μmであったのに対し、比較例は平均数１００μｍであった。
【００６６】
（２）摩擦係数評価／結果
実施例１・２について、JIS K 7125に準じて、動摩擦係数を測定した。結果は、実施例１：0.197、実施例２：0.287で、メタンガス量が多い方が、動摩擦係数が低いことが分かる。
【００６７】
（３）膜靱性評価／結果
実施例「スクラッチテスター」（スイス、CSEM社製商品名）を用いて、下記方法／条件で評価した。
【００６８】
方法…ダイヤモンド圧子（１２０°円錐形）を被膜に押し付けながら(スクラッチしながら）、連続的に荷重を０〜１００Nまで増大させていき、被膜にチッピングや剥離等の破壊現象を発生させる。通常は、破壊現象発生時を、臨界荷重値として評価するが、膜靱性はチッピング開始荷重で評価することが信頼性があるため、チッピング開始荷重で評価した。ここで「チッピング」とは、被膜の欠け（欠落）のことである。スクラッチテストを行った場合、圧子荷重の増加に伴い、被膜はスクラッチ（掻き傷）→チッピング→剥離の順で破壊されることが多い。
【００６９】
条件…圧子移動距離：１０ｍｍ、同移動速度：１０ｍｍ／min、同加重速度：1.67N／ｓ
結果は、実施例１：６０N、実施例２：４５N、比較例２：３０Nであり、本発明の各実施例、特に複合被膜の実施例１は、靱性（耐チッピング性）が格段に高いことが分かる。
【図面の簡単な説明】
【図１】本発明におけるバナジウム系複合被膜の一例を示すモデル図
【図２】本発明に使用するイオンプレーティング装置の一例を示す概略モデル図
【図３】試験例に使用する基材であるダイス鋼製金型のモデル斜視図
【符号の説明】
１２基材
１４ＶＮ膜
１６ＶＣＮ膜
１８ＶＣ膜
２０第一層間結合層
２２第二層間結合層[0001]
【Technical field】
The present invention relates to a method for forming a vanadium- based film on the surface of an inorganic substrate. In particular, the present invention relates to a method for forming a film suitable for a metal plastic working mold such as forging or press molding.
[0002]
[Background]
Conventionally, a die for press molding or the like is generally made of steel, so that it is necessary to perform a hard coating treatment in order to maintain durability such as wear resistance.
[0003]
One of the hard coating processes is a vanadium carbide (VC) film process. As a method for forming a VC film, a thermal reactive deposition and diffusion method (TRD method) has been mainly used (Japanese Patent Laid-Open Nos. 49-11837, 54-7610, and 56-18670). (See publications).
[0004]
However, in the case of the TRD method, it is necessary to set the bath temperature to 800 to 1200 ° C. (see the above publication), which is not desirable from the viewpoint of working environment, energy saving, productivity, and the like. That is, the working environment became high temperature, energy for maintaining the bath temperature was required, and it took time to cool the product after coating.
[0005]
Further, in the case of a mold whose base material (base material) is steel, the temperature is much higher than the tempering temperature of steel (usually 550 to 650 ° C .: “Semiconductor / Metal Material Glossary of Terms”, Industrial Research Committee, 1999). The base material is exposed to. For this reason, it is unsuitable in the case of a steel product that requires high dimensional accuracy such as a metal plastic working mold.
[0006]
DISCLOSURE OF THE INVENTION
In view of the above, the present invention provides a vanadium-based coating film having practical adhesion and toughness with the same hardness as that obtained by the thermal reaction precipitation diffusion method (molten salt diffusion method) even at a film formation temperature lower than the tempering temperature of steel. It is an object (problem) to provide a method for forming a vanadium-based film capable of forming a film .
[0007]
In order to solve the above problems, in the process of earnestly developing, the vanadium-based coating with low hardness has hitherto been applied to the surface of steel materials by ion plating, which has been considered to give practical adhesion and toughness. In the case of reactive film formation, the inventors have found that the above problem can be solved by adjusting and maintaining the injection gas amount / gas ratio corresponding to the film type , and have come up with a method for forming a vanadium-based film having the following configuration.
[0008]
In a method of reactively forming a vanadium- based film on the surface of an inorganic substrate by ion plating,
The vanadium-based coating is a composite coating composed of a VN film, a VCN film, and a VC film sequentially arranged from the substrate side,
Each layer of the vanadium-based coating is formed by reaction by using vanadium as an evaporation source and adjusting and maintaining the injection gas amount and gas ratio corresponding to the film type using nitrogen gas and / or hydrocarbon gas as the injection gas. It is characterized by.
[0009]
As described above, by adjusting the gas injection amount or the gas ratio, the film-forming composition is changed from a composition having good adhesion to the inorganic substrate (normally low hardness) to a good abrasion resistance (normally high hardness). ) It can be changed stepwise or continuously to the composition. The upper limit of the ion plating film forming temperature (substrate temperature) is usually 550 ° C.
[0011]
The hardness increases in the order of VN: HV2000, VCN: HV2500, and VC: HV3500, and the film-forming composition is changed from a composition having good adhesion to an inorganic substrate (normally low hardness) to wear resistance. good (usually high hardness) do not and stepwise to the composition can be continuously changed.
[0012]
Furthermore, it is desirable to carry out the reactive film formation of the interlayer bonding layers having the respective gradient compositions by changing the injection gas amount / gas ratio stepwise or continuously during the transition between the reactive film formation processes of the respective layers. This is because the drop (gap) of composition change between the respective layers is reduced, and delamination is less likely to occur when subjected to thermal shock or mechanical shock.
[0013]
Furthermore, when a steel material is used as the inorganic base material, it is desirable to adjust the substrate temperature during film formation to 400 to 500 ° C.
[0014]
As described above, the tempering temperature of the tough steel material is usually about 550 to 650 ° C. Therefore, when temperature variation is taken into consideration, 500 ° C. or less is desirable. It becomes difficult to get sex.
[0015]
The vanadium-based film-treated inorganic product obtained by reactively forming a vanadium-based film by the ion plating has the following configuration.
[0016]
In inorganic products with vanadium-based coatings on the surface of inorganic substrates,
The vanadium-based coating is a composite coating composed of a VN film, a VCN film, and a VC film sequentially arranged from the substrate side .
[0017]
Furthermore, it is desirable to interpose an interlayer coupling layer having a gradient composition between the layers of the composite coating.
[0018]
The outermost layer hardness of the composite coating is preferably Vickers hardness: HV3000 or more from the standpoint of wear resistance, and the hardness is determined by the ratio of thickness: VN film / VCN film / VC film = 0.5 / 0. It becomes easy to obtain by setting it as 5/9-3/3/4 and making it the total film thickness of 2-50 micrometers.
[0019]
In addition, the effect of the present invention can be achieved by applying a tough metal material as the inorganic base material, and being applied to a metal plastic working mold that is easily exposed to mechanical shock and thermal shock as a product and requires dimensional accuracy. Becomes even more prominent.
[0020]
JP-A-9-71856 describes a technique for forming a vanadium-based film (VC + 40% Ni) by the AIP method. However, as in the present invention, the hardness is high (HV2000 or higher, preferably HV3000 or higher). Vanadium coating is not planned.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments. In this specification, the chemical formulas VN, VCN, and VC mean vanadium nitride (cubic), vanadium carbonitride (same), and vanadium carbide (same), respectively.
[0022]
“HV” means Vickers hardness measured according to JIS Z 2244.
[0023]
FIG. 1 is a partial cross-sectional view of a vanadium-based film-treated inorganic product according to an embodiment of the present invention. Basically, a VN film 14 is disposed on the surface of a steel substrate 12 in this order from the substrate 12 side. , An inorganic product provided with a composite coating (vanadium coating) composed of the VCN film 16 and the VC film 18.
[0024]
In the above, when the VN film 14, the VCN film 16, and the VC film 18 are arranged in this order from the base material 12 side, the hardness increases in that order as described above, and the base material, particularly a steel base material (usually HV 600 to 900). And the hardness difference can be reduced. Therefore, even if the surface hardness is high, it becomes easy to ensure adhesion with the substrate. As described above, the VC film 18 is HV3500, and it is easy to ensure the surface hardness that is a factor ( parameter ) for ensuring wear resistance. If further improvement in wear resistance is required, it is desirable to reduce the friction coefficient (dynamic friction coefficient: JIS K 7125), which is another factor of wear resistance. The dynamic friction coefficient (μ) is 0.3 or less, preferably 0.2 or less. As will be described later, the friction coefficient can be easily obtained by increasing the amount of hydrocarbon (carbon source).
[0025]
In the present embodiment, although not indispensable, first and second interlayer coupling layers having a gradient composition are further provided between the layers of the composite coating, that is, between the VN film 14 / VCN film 16 and between the VCN film 16 / VC film 18. 20 and 22 are interposed.
[0026]
The presence of these interlayer bonding layers 20 and 22 further reduces the hardness difference between the respective layers, and as a result, delamination due to mechanical shock or thermal shock hardly occurs, and as a result, the toughness of the vanadium-based coating increases. That is, durability is increased.
[0027]
More specifically, the film thickness ratio of each film layer is set such that VN film 14 / VCN film 16 / VC film 18 = 0.5 / 0.5 / 9 to 3/3/4, preferably 1/1 / The thickness is 8 to 2.5 / 2.5 / 5, most preferably about 2/2/6, and the total film thickness is 2 to 50 μm, preferably 3 to 10 μm, and most preferably about 6 μm.
[0028]
If the film thickness ratio of the VC film to the VN film or the VCN film is too large, especially when the film thickness of the VC film exceeds 10 μm, the compressive stress of the film increases. Delamination with the VCN film is likely to occur. Moreover, since the film toughness is lowered, cracks are likely to occur in the VC film due to impact during forging.
[0029]
On the contrary, if the film thickness ratio of the VC film to the VN film or the VCN film is too small, the hardness of the entire film becomes HV3300 or less, and it becomes difficult to obtain wear resistance.
[0030]
Further, if the total film thickness of the composite coating is too small, it is difficult to obtain the required surface hardness (abrasion resistance), and conversely if it is too large, delamination of the vanadium-based coating from the substrate tends to occur. Further, since the film toughness is lowered, cracks are likely to occur in the coating film due to impact during pressing and forging.
[0031]
The layer thickness (film thickness) of the interlayer coupling layers 20 and 22 is much thinner than the VN film, VCN film, and VC film that are constituent layers of the vanadium-based coating. It is desirable that the layer is as thin as possible as long as it has an effect of interlayer coupling. Usually, it is 0.5 / 10 to 3/10, preferably 1/10 to 2/10, most preferably VN film and VCN film. About 1.5 / 10. The reason for the setting is estimated as follows.
[0032]
In order to suppress peeling due to the hardness difference between the substrate and the coating, it is considered sufficient to have a three-layer structure. Further, even if there is no interlayer bonding layer, the hardness difference between the coating layers is within HV1000, and therefore it is considered that a thickness greater than the above setting is not necessary for the purpose of use.
[0033]
Here , tough steel is used because metal products (inorganic products) such as metal plastic molds that are susceptible to mechanical and thermal shocks are planned, such as metal plastic molds. is there.
[0034]
As the steel material, Fe-based alloys (tough steel materials) such as high-speed steel, die steel, powdered high-speed steel, and semi-high-speed steel can be suitably used. As a base material, if it has heat resistance of 550 degreeC or more, it will not be restricted to a Fe base alloy, Ti base alloy, a copper base alloy, a cermet, ceramics etc. can be used. However, since the dimensional distortion due to tempering does not occur except for the Fe-based alloy, particularly tough steel, it is not possible to enjoy all the effects of the present invention.
[0035]
Specific examples of the Fe-based alloy include high-speed steel such as SKH51, SKH55, and SKH57, cold and hot die steel such as SKD11 and SKD61, and powder high-speed steel such as HAP10 and HAP40 (manufactured by Hitachi Metals, Ltd.). ), YXR3, YXR7, YXR33 and other semi-high speed steel (manufactured by the same company).
[0036]
Next, the manufacturing method of the inorganic product of the above embodiment, that is, the film forming method of the vanadium film will be described.
[0037]
In this embodiment, an ion plating apparatus as shown in FIG. 2, usually an arc ion plating (AIP) apparatus, is used. The AIP method uses vanadium as an evaporation source, nitrogen gas and / or hydrocarbon gas as an injection gas, and adjusts and maintains the injection gas amount and gas ratio according to the film type and film thickness, thereby providing a VN film, a VCN film, This is because it is easy to reactively form a VC film on a substrate with high purity. Naturally, other types of ion plating methods such as a multi-cathode thermionic irradiation method, a high-frequency excitation method, a holo-cathode discharge method, a cluster method, and an activated reaction deposition method are also possible.
[0038]
In the ion plating apparatus, an evaporation source holding part (pot part) 25 for holding vanadium metal and a workpiece (base material) 28 connected to a bias voltage source 26 are placed in a chamber 24. It has. Furthermore, the chamber 24 includes an exhaust port 32 connected to an exhaust pump that maintains the inside of the chamber at a predetermined degree of vacuum, and a reaction gas introduction port 34 for introducing a reaction gas (nitrogen and / or methane). A heater 36 that maintains the interior at a predetermined temperature and also maintains the substrate (substrate) 28 at a predetermined temperature is provided.
[0039]
An example of reactive film formation by the AIP method will be described.
[0040]
The vanadium (V) used as the evaporation source is usually one having a purity of tunaine to threeine. In addition, the gas that is the source of nitrogen and carbon, which are elements that react with vanadium, can use nitrogen gas (N ₂ ) for the former and hydrocarbon gases such as methane (CH ₄ ), ethane, ethylene, acetylene for the latter It is. As the hydrocarbon gas, methane is preferable because it does not easily generate soot because unreactive gas contaminates the surface of the apparatus and the base material. And the purity of each is made from three nine to six nine.
[0041]
The film formation conditions by the AIP method are as shown in Table 1.
[0042]
[Table 1]

[0043]
The focus points of the above condition items will be described below.
[0044]
(1) Degree of vacuum:
If the degree of vacuum is too high (the absolute pressure is low), the amount of reaction gas will be small, the film forming speed will be slowed and the productivity will be reduced, and the formed film will have a composition with excessive metal components. It tends to become rough, or the particles are coarse and have many voids (it is estimated that the generation of crystal nuclei is delayed).
[0045]
On the other hand, if the degree of vacuum is too low (the absolute pressure is high), the amount of reaction gas becomes excessive, and the gas that is not fully activated without being used in the reaction acts as an adsorption inhibitor (inhibitor) on the growth film surface. There is a risk.
[0046]
In particular, when application of the present invention to a mold is expected to improve wear resistance, the surface film (VC film) is required to have slipperiness as well as film hardness. In such a case, it acts as a lubricant. It is desirable to contain C (carbon) in the film. However, when the C content is excessive, the film hardness is lowered and the wear resistance is also lowered. The degree of vacuum that can achieve such a balance is about 25 to 35 mtorr (33.3 to 46.6 Pa), preferably about 30 mtorr (39.9 Pa), and the amount of methane gas is about 400 to 600 mL / min, preferably about 500 mL / min.
[0047]
(2) Arc current:
If the current value is too low, the deposition rate is slow, and conversely if too high, it is not desirable from the viewpoint of the safety of the apparatus.
[0048]
(3) Bias voltage:
In general, the higher the bias voltage, the slower the film formation speed. Therefore, it is set within an appropriate range in consideration of productivity. When the supply gas is nitrogen (N ₂ ), there is almost no influence on the nitride film crystal of the bias voltage, and the voltage can be appropriately set within the range of 50 to 400V, preferably 50 to 200V. In the case of a hydrocarbon such as CH ₄ , if the bias voltage is low, the crystallinity of VC becomes low and it becomes difficult to obtain the wear resistance of the carbide film. For this reason, it is possible in the range of 50 to 400 V as in the case of nitrogen, but is preferably about 100 to 200 V, more preferably about 150 V, from the balance between productivity and crystallinity.
[0049]
(4) Substrate temperature:
The higher the temperature, the faster the film formation rate is desirable, but from the viewpoint of energy saving and heat resistance of the base material, when the base material is steel, the temperature is not higher than the temperature at which dimensional distortion due to tempering does not occur, usually 350 to 550 ° C, preferably Set to 400 to 500 ° C. In the case where thermal distortion does not occur as in the case of ceramics, it may be carried out at a maximum ion plating temperature of around 550 ° C.
[0050]
Table 2 shows an example of the gas flow rate and deposition time when an interlayer coupling layer is formed between the layers. In Table 2, X varies depending on the vanadium filling amount and the film thickness. For example, when the filling amount is 800 g and the total film thickness is 3 to 10 μm, X = 300 to 1000 seconds.
[0051]
[Table 2]

[0052]
The amount and pressure of the gas in each interlayer bonding layer in Table 2 do not instantaneously become the amount and pressure, but usually increase continuously to the pressure after an intermediate time of film formation, for example, 40 to 50 seconds. Thereafter, the set value is maintained. The same applies to the VCN film and the VC film.
[0053]
In the above description, the VN film / VCN film / VC film composite film has been described as an example of the vanadium-based film. However, the VN film, the VCN film, and the VC film may each be a single layer film. Films, VCN film / VC film, and VN film / VC film composite films can be formed in the same manner. When steel is used as a base material and a composite film is used, in principle, it is desirable that the lower hardness is the base material side, and an interlayer coupling layer is formed between each layer.
[0054]
Therefore, in the film forming method of the present invention, even a VN film having the lowest hardness has a hardness of HV2000, and a vanadium-based film having a hardness of HV3000 or higher can be easily formed on a substrate such as steel with good adhesion.
[0055]
In addition, the vanadium-based coating film forming method of the present invention is not limited to a metal plastic working mold, but also any inorganic product that requires wear resistance, such as a cylinder liner, a valve lifter, a sprocket, a gear, a pulley, an axle. It can be applied to transportation-related members such as, machine parts, jigs and the like.
[0056]
[Test example]
Next, test examples conducted for Examples 1, 2, and 3 and Comparative Examples 1 and 2 in order to confirm the effect of the present invention will be described.
[0057]
As the ion plating apparatus, “AIP4024 type” manufactured by Kobe Steel, Ltd. was used. V was filled with 800 g of pure three nine, N ₂ was pure five nine, and CH ₄ was pure three nine.
[0058]
Example 1 In Table 2, a vanadium-based film (VN film / VCN film / VC film) having a total film thickness of about 6 μm was formed on the press surface of a mold having a vanadium-based film as a base material with X = 600 s. The base material was a die for press working (FIG. 3: 150 mmφ × 70 mmt) made of cold die steel (SKD11: HV650, same as HRC58.0 toughness evaluation).
[0059]
Example 2: In Example 1, the set pressure was 20 mtorr (26.6 Pa). Other conditions are the same as in Example 1.
[0060]
Example 3 In Example 1, a single-layer VC film having a thickness of about 6 μm was formed with X = 3000 s. Other conditions are the same as in Example 1.
[0061]
In Comparative Examples 1 and 2, a single-layer VC film and a single-layer TiC film each having a film thickness of about 6 μm are formed on the same base material as in Example 1 (press made by SKD11), based on the thermal CVD method and the TRD method. Film formation (film formation temperature: about 1000 ° C.) was performed on the molding die.
[0062]
And the test of the following item was done about the metal mold | die of each Example and comparative example obtained above.
[0063]
(1) Durability Evaluation Test With respect to Example 1 and Comparative Example 1, the number of moldings of a mold life (molding failure due to wear) until a defective product was generated was evaluated using a work material (SUS, 3 mmt).
[0064]
The mold life of Example 1 was 60,000, whereas Comparative Example 1 was about 40,000.
[0065]
At this time, the dimensional distortion of the mold was measured. In Example 1, the maximum was ± 40 μm, while the comparative example had an average number of 100 μm.
[0066]
(2) Friction coefficient evaluation / results For Examples 1 and 2, the dynamic friction coefficient was measured according to JIS K 7125. The results are Example 1: 0.197 and Example 2: 0.287, and it can be seen that the larger the amount of methane gas, the lower the dynamic friction coefficient.
[0067]
(3) Evaluation of film toughness / result Using the example “scratch tester” (trade name, manufactured by CSEM, Switzerland), evaluation was carried out according to the following methods / conditions.
[0068]
While pressing method ... diamond indenter (120 ° conical) in the coating (scratch while), will continuously increase the load to 0～100N, make generates a breakdown phenomenon of chipping and peeling the film. Normally, the occurrence of a fracture phenomenon is evaluated as a critical load value. However, since film toughness is reliable to be evaluated with a chipping start load, it was evaluated with a chipping start load. Here, “chipping” means chipping (missing) of the film. When the scratch test is performed, the coating is often broken in the order of scratch (scratching) → chipping → peeling with an increase in indenter load.
[0069]
Conditions: Indenter travel distance: 10 mm, same travel speed: 10 mm / min, same load speed: 1.67 N / s
The results are Example 1: 60N, Example 2: 45N, and Comparative Example 2: 30N, and each of the examples of the present invention, particularly Example 1 of the composite coating, has extremely high toughness (chipping resistance). I understand.
[Brief description of the drawings]
FIG. 1 is a model diagram showing an example of a vanadium-based composite coating in the present invention. FIG. 2 is a schematic model diagram showing an example of an ion plating apparatus used in the present invention. FIG. 3 is a base material used in a test example. Model perspective view of die steel mold [Explanation of symbols]
12 Substrate 14 VN film 16 VCN film 18 VC film 20 First interlayer coupling layer 22 Second interlayer coupling layer

Claims

In a method of reactively forming a vanadium- based film on the surface of an inorganic substrate by ion plating ,
The vanadium-based coating is a composite coating composed of a VN film, a VCN film, and a VC film sequentially arranged from the substrate side,
Each layer of the vanadium-based coating is formed by reaction by using vanadium as an evaporation source and adjusting and maintaining the injection gas amount and gas ratio corresponding to the film type using nitrogen gas and / or hydrocarbon gas as the injection gas. A method for forming a vanadium-based film characterized by the above.

In the transition between the reaction film forming process of the layers, the injection gas amount and gas ratio stepwise or continuously changing the characterized by reacting deposited interlayer coupling layer of the gradient composition in the claim 1, wherein A method for forming a vanadium-based film.

The method for forming a vanadium-based film according to claim 1 or 2, wherein a steel material is used as the inorganic base material, and the substrate temperature during film formation is adjusted to 400 to 500 ° C.

In inorganic products with vanadium-based coatings on the surface of inorganic substrates,
The vanadium-based coating- treated inorganic product , wherein the vanadium-based coating is a composite coating composed of a VN film, a VCN film, and a VC film sequentially arranged from the substrate side .

5. The vanadium-based film-treated inorganic product according to claim 4, wherein an interlayer bonding layer having a gradient composition is further interposed between the layers of the composite film.

6. The vanadium-based coated inorganic product according to claim 4 or 5, wherein the outermost layer hardness of the composite coating is Vickers hardness: HV3000 or more.

In the composite coating, the film thickness ratio is VN film / VCN film / VC film = 0.5 / 0.5 / 9 to 3/3/4, and the total film thickness is 2 to 50 μm. The inorganic product treated with vanadium film according to claim 6 .

The vanadium-based film-treated inorganic product according to claim 6, wherein the inorganic base material is a steel material.

The vanadium-based film- treated inorganic product according to claim 7, wherein the inorganic base material is a steel material.

10. The vanadium-based film-treated inorganic product according to claim 8 or 9, wherein the applied product is a metal plastic working mold.

The vanadium-based coated inorganic product according to claim 7, 8 or 9, wherein the VC film contains carbon particles (carbon particles).

The vanadium-based coated inorganic product according to claim 10, wherein the VC film contains carbon particles (carbon particles).