JP6489505B2 - Diamond coated cemented carbide cutting tool with improved cutting edge strength - Google Patents
Diamond coated cemented carbide cutting tool with improved cutting edge strength Download PDFInfo
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- 229910052721 tungsten Inorganic materials 0.000 claims description 14
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 229910017052 cobalt Inorganic materials 0.000 claims description 8
- 239000010941 cobalt Substances 0.000 claims description 8
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 4
- 239000010937 tungsten Substances 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 2
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 2
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Description
本発明は、ＣＦＲＰ等の難削材の高速切削加工において、刃先がすぐれた靭性および強度を備え、長期の使用にわたってすぐれた耐チッピング性、耐摩耗性を発揮するダイヤモンド被覆炭化タングステン基超硬合金製切削工具に関する。 The present invention provides a diamond-coated tungsten carbide-based cemented carbide based on high-speed cutting of difficult-to-cut materials such as CFRP, which has excellent toughness and strength at the cutting edge and excellent chipping resistance and wear resistance over a long period of use. The present invention relates to a cutting tool.
従来、炭化タングステン基超硬合金（以下、「ＷＣ基超硬合金」あるいは単に「超硬合金」という）からなる基体に、ダイヤモンド膜を被覆したダイヤモンド被覆超硬合金製切削工具が知られているが、従来のダイヤモンド被覆超硬合金製切削工具においては、超硬合金基体とダイヤモンド膜の密着性が十分でないため、これを改善するために超硬合金基体上にダイヤモンドを成膜する際に、ダイヤモンドの形成を阻害するコバルトを除去させた基体上に成膜する（特許文献１〜３参照）、あるいは、超硬合金の結合相成分としてＣｒ等を含有させる（特許文献４〜７参照）などの種々の提案がなされている。 Conventionally, a diamond-coated cemented carbide cutting tool in which a base made of a tungsten carbide-based cemented carbide (hereinafter referred to as a “WC-based cemented carbide” or simply “a cemented carbide”) is coated with a diamond film is known. However, in the conventional diamond-coated cemented carbide cutting tool, the adhesion between the cemented carbide substrate and the diamond film is not sufficient, so when diamond is deposited on the cemented carbide substrate to improve this, A film is formed on a substrate from which cobalt that inhibits diamond formation is removed (see Patent Documents 1 to 3), or Cr or the like is contained as a binder phase component of a cemented carbide (see Patent Documents 4 to 7). Various proposals have been made.
例えば、特許文献１〜３に示すように、ＷＣ基超硬合金製工具基体をダイヤモンドで被覆するにあたり、その表面を、ムラカミ（Ｍｕｒａｋａｍｉ）試薬と酸により２段階、あるいは、３段階でエッチングし、工具基体とダイヤモンド膜の密着性を改善することが提案されている。 For example, as shown in Patent Documents 1 to 3, when a WC-based cemented carbide tool base is coated with diamond, the surface is etched in two stages or three stages with a Murakami reagent and an acid, It has been proposed to improve the adhesion between the tool substrate and the diamond film.
また、特許文献４には、切削工具等に用いられる超硬合金において、Ｔｉ，Ｚｒ，Ｈｆ，Ｔａ，Ｎｂ，Ｖ，Ｃｒ，Ｍｏ，希土類元素、これらの相互合金、それら元素の炭化物、窒化物、酸化物、およびこれらの相互固溶体から選ばれた少なくとも１種からなる改質物質を、表面から０．２ｍｍ内部までに該改質物質の含有量が最大となる最大含有量位置を有し、その位置からさらに内部に向かって該改質物質が漸減されており、該最大含有量位置における該改質物質含有量を金属元素換算で測定したときに、該金属元素の含有量が焼結合金全体に対し１質量％以下とすることによって、超硬合金の組織構造と特性を改質することが提案されている。 Patent Document 4 discloses a cemented carbide used for cutting tools and the like, Ti, Zr, Hf, Ta, Nb, V, Cr, Mo, rare earth elements, their mutual alloys, carbides of these elements, and nitrides. A modified substance consisting of at least one selected from oxides and their mutual solid solutions has a maximum content position where the content of the modified substance is maximized from the surface to the inside of 0.2 mm; The reforming substance is gradually reduced from the position toward the inside, and when the reforming substance content at the maximum content position is measured in terms of a metal element, the content of the metal element is a sintered alloy. It has been proposed to modify the structure and properties of cemented carbide by setting the content to 1% by mass or less based on the total.
特許文献５には、Ｃｏおよび／またはＮｉの結合金属を２〜２０重量％、周期律表第４ａ、５ａ、６ａ族金属の群から選ばれる少なくとも１種の炭化物、窒化物および／または炭窒化物を０〜３０重量％含有するともに、Ｆｅを１０〜３００ｐｐｍ、Ｃｒを１００〜１０００ｐｐｍ含有し、残部が炭化タングステン（以下、「ＷＣ」で示す）と不可避不純物からなる超硬合金において、この超硬合金の表面近傍に、この超硬合金内部の前記結合金属の総含有量をｗ１ｉｎ、この超硬合金内部のＦｅおよびＣｒの総含有量をｗ２ｉｎ、この超硬合金表面領域の前記結合金属の総含有量をｗ１ｓｕｆ、この超硬合金表面領域のＦｅおよびＣｒの総含有量をｗ２ｓｕｆとし、ｐｉｎ＝ｗ２ｉｎ／ｗ１ｉｎ、ｐｓｕｆ＝ｗ２ｓｕｆ／ｗ１ｓｕｆとしたとき、ｐｓｕｆ＜ｐｉｎの条件を満足する表面領域を形成することによって、超硬合金表面を、高強度化、高靭性化することが提案されている。 Patent Document 5 discloses that at least one carbide, nitride, and / or carbonitriding selected from the group consisting of 2 to 20% by weight of Co and / or Ni bonding metal and Group 4a, 5a, and 6a metals in the periodic table. In a cemented carbide containing 10 to 300 ppm of Fe, 100 to 1000 ppm of Cr, and the balance of tungsten carbide (hereinafter referred to as “WC”) and inevitable impurities. Near the surface of the hard alloy, the total content of the bonding metal in the cemented carbide is w 1in , the total content of Fe and Cr in the cemented carbide is w 2in , and the bonding of the cemented carbide surface region the total content of metal w 1suf, the total content of Fe and Cr in the cemented carbide surface area as w 2suf, p in = w 2in / w 1in, p suf = w 2suf / w 1 when the uf, by forming a surface region that satisfies the conditions of the p suf <p in, cemented carbide surface, high strength, it is proposed that a high toughness.
特許文献６には、ダイヤモンド被覆超硬合金製切削工具において、ダイヤモンド膜が、平均膜厚３〜３０μｍの層厚を有し、工具基体とダイヤモンド膜の界面から工具基体の内部方向へ大きくとも５μｍの深さ領域に、Ｃｏを主成分とする金属結合相の一部が除去された金属結合相一部除去領域を有し、当該工具の刃先近傍の逃げ面の垂直断面における観察で前記金属結合相一部除去領域内のＣｒのＣｏに対する質量比が、０．０５以上０．２１未満の範囲であるとともに工具基体の１００μｍ以上内部における金属結合相における質量比と比較して、１．２〜３．０倍とすることにより、ダイヤモンド膜と工具基体との耐剥離性を向上させるとともに刃先強度を向上させ、耐チッピング性および耐摩耗性を向上させることが提案されている。 In Patent Document 6, in a diamond-coated cemented carbide cutting tool, the diamond film has an average film thickness of 3 to 30 μm, and at most 5 μm from the interface between the tool base and the diamond film toward the inside of the tool base. In the depth region, the metal bonding phase partially removed region from which a part of the metal bonding phase mainly composed of Co is removed, and the metal bonding is observed in a vertical cross section of the flank near the cutting edge of the tool. The mass ratio of Cr to Co in the phase partial removal region is in the range of 0.05 or more and less than 0.21, and is 1.2 to 2.0 in comparison with the mass ratio in the metal bonded phase inside the tool substrate of 100 μm or more. It has been proposed to increase the peeling resistance between the diamond film and the tool base as well as to improve the cutting edge strength and to improve the chipping resistance and wear resistance by setting the ratio to 3.0 times.
特許文献７には、ダイヤモンド被覆超硬合金製切削工具において、工具基体とダイヤモンド膜の界面から工具基体内部方向へ大きくとも８μｍの深さにおける金属結合相の一部が化学処理によって除去された金属結合相一部除去領域を有し、刃先近傍（刃先の先端より大きくとも１００μｍを超えない領域）の逃げ面の垂直断面における観察で金属結合相一部除去領域内のＷＣ粒子同士およびＷＣ粒子と他の炭化物との接合粒界を除くＷＣ粒界に１０〜３００ｎｍの厚みの金属結合相が前記ＷＣ粒界長の５０％以上の割合で存在し、ＷＣ粒界に存在する金属結合相におけるＣｒのＣｏに対する質量割合を０．２１以上０．４０以下とすることにより、ダイヤモンド膜と工具基体との耐剥離性を向上させるとともに刃先強度を向上させ、耐チッピング性および耐摩耗性を向上させることが提案されている。 In Patent Document 7, in a diamond-coated cemented carbide cutting tool, a metal in which a part of a metal bonding phase at a depth of at most 8 μm from the interface between the tool base and the diamond film to the inside of the tool base is removed by chemical treatment. WC particles in the metal bonded phase partial removal region and WC particles in the vertical cross section of the flank in the vicinity of the blade edge (region not exceeding 100 μm at the maximum) A metal bonded phase having a thickness of 10 to 300 nm is present at a ratio of 50% or more of the WC grain boundary length at the WC grain boundary excluding the joint grain boundary with other carbides, and Cr in the metal bonded phase existing at the WC grain boundary. By making the mass ratio of Co to 0.21 or more and 0.40 or less, the resistance to peeling between the diamond film and the tool base is improved and the strength of the blade edge is improved. It has been proposed to improve wearability and wear resistance.
近年の切削加工の技術分野における省力化および省エネ化、さらに低コスト化に対する要求は強く、これに伴い、切削加工は益々高速化の傾向にあるが、前記従来ダイヤモンド被覆超硬合金製切削工具（以下、単に「ダイヤモンド被覆工具」という）を、例えば、ＣＦＲＰ材等の難削材のドリル加工の様な鋭利な刃先が要求される切削加工に供した場合には、前処理後の超硬合金製工具基体の靭性が十分でないためチッピングを発生しやすく、早期に寿命に至る場合があった。また、ＣＦＲＰ材等の難削材を高速切削する場合には、特に高い刃先強度が要求されるが、従来ダイヤモンド被覆工具は、刃先強度が十分でなく、また、ダイヤモンド膜の剥離が生じやすいため、長期の使用に亘って、満足できる耐チッピング性および耐摩耗性を発揮することはできず、その結果、比較的短時間で使用寿命に至ることが多かった。 In recent years, there has been a strong demand for labor saving, energy saving, and cost reduction in the technical field of cutting, and along with this, cutting tends to increase more and more, but the conventional diamond coated cemented carbide cutting tool ( (Hereinafter simply referred to as “diamond-coated tool”), for example, when it is subjected to cutting that requires a sharp cutting edge such as drilling of difficult-to-cut materials such as CFRP materials. Since the toughness of the tool base is not sufficient, chipping is likely to occur, and the life may be shortened early. Moreover, when cutting difficult-to-cut materials such as CFRP materials at a high speed, particularly high cutting edge strength is required, but conventional diamond-coated tools have insufficient cutting edge strength, and the diamond film tends to peel off. However, satisfactory chipping resistance and wear resistance cannot be exhibited over a long period of use, and as a result, the service life is often reached in a relatively short time.
前述のようなダイヤモンド被覆工具の課題について本発明者らが鋭意研究を行ったところ、ダイヤモンド被覆工具においては、前述のようにダイヤモンド膜と工具基体との密着性を上げるために工具基体の最表面に存在する金属結合相中のＣｏを除去する処理を行っているが、その結果、刃先における靭性の低下を招き、刃先強度低下の原因となっていることを突き止めた。 As a result of the diligent research conducted by the present inventors on the problems of the diamond-coated tool as described above, in the diamond-coated tool, as described above, in order to improve the adhesion between the diamond film and the tool base, As a result, it was found that the toughness of the cutting edge was lowered and the strength of the cutting edge was reduced.
そこで、本発明が解決しようとする技術的課題、すなわち本発明の目的は、ダイヤモンド被覆工具において、ダイヤモンド膜と工具基体との密着性を向上させるとともに前処理後の工具基体の刃先の靭性を維持させることにより、ダイヤモンド被覆工具の刃先強度を向上させ、耐チッピング性および耐摩耗性を向上させたダイヤモンド被覆工具を提供することである。 Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention is to improve the adhesion between the diamond film and the tool base and maintain the toughness of the edge of the tool base after the pretreatment in the diamond coated tool. It is to provide a diamond coated tool with improved edge strength of the diamond coated tool and improved chipping resistance and wear resistance.
本発明者らは、例えば、ＣＦＲＰの高速穴あけ加工や高速エンドミル加工のように、刃先に高負荷が作用する切削条件に供した場合でも、チッピング、欠損、剥離等を抑制し、耐摩耗性を発揮するダイヤモンド被覆工具を提供すべく、工具基体表面近傍に存在するＷＣ粒子に着目し鋭意検討したところ、次のような知見を得た。 Even when the present inventors are subjected to cutting conditions in which a high load acts on the blade edge, such as high-speed drilling or high-speed end milling of CFRP, the chipping, chipping, peeling, etc. are suppressed, and wear resistance is improved. In order to provide a diamond-coated tool to be exhibited, the inventors have made extensive studies focusing on the WC particles existing in the vicinity of the tool base surface, and obtained the following knowledge.
すなわち、主としてＷＣ粒子からなる硬質相と主としてＣｏからなる結合相とで構成された超硬合金からなる工具基体表面に化学的処理等を施し、結合相の一部を除去（以下、単に「エッチング」ともいう）した場合、工具基体表面のＣｏの除去によって、ダイヤモンド膜と工具基体との密着強度が高められるが、その反面、工具基体表面におけるＷＣ粒子と結合相間の結合強さ、あるいは、ＷＣ粒子相互間の結合強さが低下する。
そして、この結合強さの低下が、ダイヤモンド膜と工具基体との界面強度の低下を招く原因でもあるが、本発明者らは、エッチングにより工具基体表面から結合相の一部を除去した場合であっても、結合相とＷＣ粒子との結合強さを高めておくことによって、工具基体表面の強度低下を招くことなく、その結果として、ダイヤモンド膜と工具基体との界面強度の低下を招くことなく、ダイヤモンド被覆工具の耐チッピング性、耐欠損性、を高め、剥離を抑制するできることを見出したのである。
That is, the surface of a tool substrate made of a cemented carbide composed mainly of a hard phase mainly composed of WC particles and a binder phase mainly composed of Co is subjected to chemical treatment or the like to remove a part of the binder phase (hereinafter simply referred to as “etching”). In this case, the adhesion strength between the diamond film and the tool base is increased by removing Co on the surface of the tool base. On the other hand, the bond strength between the WC particles and the binder phase on the surface of the tool base, or WC The bond strength between particles decreases.
This decrease in bond strength is also a cause of a decrease in the interfacial strength between the diamond film and the tool base, but the present inventors are in the case where a part of the bond phase is removed from the tool base surface by etching. Even so, by increasing the bond strength between the binder phase and the WC particles, the strength of the surface of the tool substrate is not decreased, and as a result, the interface strength between the diamond film and the tool substrate is decreased. The present inventors have found that the chipping resistance and fracture resistance of the diamond-coated tool can be improved and peeling can be suppressed.
より具体的に言えば、次のとおりである。
本発明では、まず、超硬合金作製用の原料粉末の一つとして、Ｃ含有量の少ないＷＣ粉末を用い、焼結後の結合相中に耐食性に優れるＣｒ−Ｗ−Ｃｏ合金が形成されやすいような原料粉末を作製する。そして、この原料粉末からなる成形体を１Ｐａの真空中で１３８０〜１５００℃にて１〜２時間焼結し、その後２０℃／ｍｉｎの冷却速度で５００℃まで冷却後、８００℃にて１５〜２０時間維持することにより、ＷＣ粒子近傍における結合相中へのＣｒとＷの濃化を促進し、ＣｒおよびＷが濃化された結合相とＷＣ粒子との界面強度を向上させる。さらに５００℃まで冷却した後、大気雰囲気にて室温にまで冷却し、結合相が酸素を含むことで、エッチングされにくい結合相が形成された工具基体を作製する。
ついで、工具基体の表面近傍の結合相の一部を化学的なエッチング（例えば、硫酸＋過酸化水素）によって除去し、工具基体表面近傍で結合相が一部除去された領域（以下、「結合相一部除去領域」という）を形成する。
そして、このような工具基体の表面に、ダイヤモンド膜を成膜すると、工具基体表面近傍の結合相のＣｏは一部除去されているため、工具基体へのダイヤモンド膜の付着強度が向上する。
一方、前記のとおり、結合相が酸素を含むことでエッチングを受けにくくなっているので、エッチングによって、結合相一部除去領域の深さが過度に大きくなることはなく、また、ＣｒおよびＷが濃化された結合相とＷＣ粒子との界面強度は高く保たれるため、特に、工具基体の刃先の靱性が低下することもない。
したがって、本発明のダイヤモンド被覆工具は、ＣＦＲＰの高速穴あけ加工やエンドミル高速加工のように、刃先に高負荷が作用する切削条件に供した場合でも、チッピング、欠損、剥離等を発生することなく、すぐれた耐摩耗性を発揮することを見出したのである。
More specifically, it is as follows.
In the present invention, first, a WC powder having a low C content is used as one of raw material powders for producing a cemented carbide, and a Cr—W—Co alloy having excellent corrosion resistance is easily formed in a sintered binder phase. Such raw material powder is prepared. And the compact | molding | casting which consists of this raw material powder is sintered at 1380-1500 degreeC for 1 to 2 hours in the vacuum of 1 Pa, Then, after cooling to 500 degreeC with the cooling rate of 20 degreeC / min, it is 15-800 at 800 degreeC. By maintaining for 20 hours, the enrichment of Cr and W in the binder phase in the vicinity of the WC particles is promoted, and the interface strength between the binder phase enriched with Cr and W and the WC particles is improved. Further, after cooling to 500 ° C., it is cooled to room temperature in an air atmosphere, and a tool base in which a binder phase that is difficult to be etched is formed because the binder phase contains oxygen is produced.
Next, a part of the binder phase in the vicinity of the tool base surface is removed by chemical etching (for example, sulfuric acid + hydrogen peroxide), and a part of the binder phase in the vicinity of the tool base surface is removed (hereinafter referred to as “bond”). Phase partial removal region ”).
When a diamond film is formed on the surface of such a tool base, the bonding phase Co in the vicinity of the tool base surface is partially removed, so that the adhesion strength of the diamond film to the tool base is improved.
On the other hand, as described above, since the binder phase is difficult to be etched because it contains oxygen, the depth of the partially removed region of the binder phase is not excessively increased by etching. Since the interface strength between the concentrated binder phase and the WC particles is kept high, the toughness of the cutting edge of the tool base is not particularly deteriorated.
Therefore, the diamond-coated tool of the present invention does not cause chipping, chipping, peeling, etc. even when subjected to cutting conditions in which a high load acts on the cutting edge, such as high-speed drilling of CFRP and high-speed machining of end mills, They have found that they have excellent wear resistance.
本発明は、前記知見に基づいてなされたものであって、
「 炭化タングステンと３〜１５質量％のコバルトを主成分とし、さらに、少なくとも０．１〜３質量％のクロムを含有する炭化タングステン基超硬合金からなる工具基体にダイヤモンド膜を被覆形成したダイヤモンド被覆超硬合金製切削工具であって、
前記ダイヤモンド膜は、３〜３０μｍの平均膜厚を有し、
前記炭化タングステン基超硬合金からなる工具基体とダイヤモンド膜の界面から工具基体内部方向へ最大８μｍの深さにおいて結合相の一部が除去された結合相一部除去領域が形成され、
前記工具基体の少なくとも刃先近傍の逃げ面の垂直断面においては、前記結合相一部除去領域内の炭化タングステン同士および炭化タングステンと他の炭化物との接合粒界を除く炭化タングステン粒界に、１０〜３００ｎｍの厚みの残留結合相が前記炭化タングステン粒界長の５０％以上の割合で存在し、
前記炭化タングステン粒界に存在する残留結合相におけるクロムのコバルトに対する質量比が０．０２以上０．１５以下、また、タングステンのコバルトに対する質量比が０．０８以上０．２０以下であり、さらに、前記結合相一部除去領域に存在する残留結合相に酸素が含まれ、残留結合相における酸素のコバルトに対する質量比が０．０２以上０．０８以下であることを特徴とするダイヤモンド被覆超硬合金製切削工具。」
を特徴とするものである。
The present invention has been made based on the above findings,
“Diamond coating in which a diamond film is coated on a tool substrate made of a tungsten carbide-based cemented carbide containing tungsten carbide and 3 to 15% by mass of cobalt and further containing at least 0.1 to 3% by mass of chromium. A cemented carbide cutting tool,
The diamond film has an average film thickness of 3 to 30 μm,
A binder phase partial removal region is formed in which a part of the binder phase is removed at a depth of 8 μm at the maximum from the interface between the tool base and the diamond film made of the tungsten carbide base cemented carbide to the inside of the tool base,
In the vertical cross section of the flank at least near the cutting edge of the tool base, the tungsten carbide grain boundaries excluding the joint grains between tungsten carbides and tungsten carbide and other carbides in the binder phase partial removal region are 10 to 10. A residual binder phase having a thickness of 300 nm is present in a proportion of 50% or more of the tungsten carbide grain boundary length;
The mass ratio of chromium to cobalt in the residual bonded phase present in the tungsten carbide grain boundary is 0.02 to 0.15, the mass ratio of tungsten to cobalt is 0.08 to 0.20, A diamond-coated cemented carbide characterized in that oxygen is contained in a residual bonded phase existing in the bonded phase partial removal region, and a mass ratio of oxygen to cobalt in the residual bonded phase is 0.02 or more and 0.08 or less. Cutting tool made. "
It is characterized by.
以下、本発明について詳細に説明する。 Hereinafter, the present invention will be described in detail.
炭化タングステン基超硬合金からなる工具基体：
本発明のダイヤモンド被覆工具の工具基体は、結合相を構成する主成分としてのＣｏを３〜１５質量％含有し、該結合相に一部固溶する成分であるＣｒを０．１〜３質量％を含有し、残部は、主として、硬質相成分としてのＷＣ粒子からなるＷＣ基超硬合金である。
なお、硬質相成分であるＷＣ粒子の一部のＷ成分は、Ｃｏ主体の結合相中にＣｏとは別のＣｒ−Ｗ−Ｃｏ合金相を形成する。
また、通常のＷＣ基超硬合金においては、耐熱性を増すためにＴｉＣ、ＴａＣ、ＮｂＣ、ＶＣ、ＺｒＣ等の炭化物を添加したり、耐蝕性を増すために結合相成分であるＣｏの一部をＮｉに置換したりすることがあるが、本発明のＷＣ基超硬合金基体においても、配合組成で、ＴｉＣ、ＴａＣ、ＮｂＣ、ＶＣ、ＺｒＣ、Ｎｉの内の１種または２種以上を合計で０．１〜１０．０質量％含有することは許容される。
Tool substrate made of tungsten carbide based cemented carbide:
The tool base of the diamond-coated tool of the present invention contains 3 to 15% by mass of Co as a main component constituting the binder phase, and 0.1 to 3% by mass of Cr, which is a component partially dissolved in the binder phase. The balance is mainly a WC-based cemented carbide composed of WC particles as a hard phase component.
A part of the W component of the WC particles as the hard phase component forms a Cr—W—Co alloy phase different from Co in the Co-based binder phase.
In addition, in ordinary WC-based cemented carbides, carbides such as TiC, TaC, NbC, VC, and ZrC are added to increase heat resistance, and a part of Co that is a binder phase component is added to increase corrosion resistance. In the WC-base cemented carbide substrate of the present invention, the total composition of one or more of TiC, TaC, NbC, VC, ZrC, and Ni is also included in the present invention. It is permissible to contain 0.1 to 10.0% by mass.
ＷＣ基超硬合金からなる工具基体を構成する成分のうち、Ｃｏ成分には、金属結合相を形成して工具基体の強度および靭性を向上させる作用があるが、ＷＣ基超硬合金中のＣｏ含有量が３質量％未満では、特に工具基体の靭性の向上が望めず、一方、Ｃｏ含有量が１５質量％を越えると、工具基体の塑性変形が起り易くなり、偏摩耗の進行が促進され、かつダイヤモンド膜の剥離を生じやすくなることから、ＷＣ基超硬合金のＣｏ含有量は３〜１５質量％と定めた。
また、Ｃｒ成分は、その一部が結合相中に固溶し、結合相の耐食性を高めるが、０．１質量％未満の含有量では、結合相中に固溶するＣｒ量が少なく、工具基体の耐食性の向上を図れないばかりか、ダイヤモンド膜の密着性向上のためのエッチング処理を行った際に、ＷＣ粒子の周りの結合相がすべて除去されてしまうため、工具基体として求められる強度を維持することができない。一方、Ｃｒ含有量が３．０質量％を超える場合は、Ｃｒ炭化物の形成により工具基体の靱性および強度が低下することから、ＷＣ基超硬合金のＣｒ含有量は０．１〜３．０質量％と定めた。
Among the components constituting a tool base made of a WC-based cemented carbide, the Co component has an effect of improving the strength and toughness of the tool base by forming a metal bonded phase. If the content is less than 3% by mass, improvement in toughness of the tool base cannot be expected. On the other hand, if the Co content exceeds 15% by mass, plastic deformation of the tool base tends to occur and the progress of uneven wear is promoted. And since it becomes easy to produce peeling of a diamond film, Co content of a WC base cemented carbide alloy was determined as 3-15 mass%.
Further, the Cr component is partly dissolved in the binder phase to improve the corrosion resistance of the binder phase. However, when the content is less than 0.1% by mass, the amount of Cr dissolved in the binder phase is small, and the tool Not only can the corrosion resistance of the substrate not be improved, but also when the etching process for improving the adhesion of the diamond film is performed, all the binder phase around the WC particles is removed, so that the strength required for the tool substrate is increased. It cannot be maintained. On the other hand, when the Cr content exceeds 3.0% by mass, the toughness and strength of the tool base decrease due to the formation of Cr carbide, so the Cr content of the WC-based cemented carbide is 0.1 to 3.0. The mass% was determined.
ダイヤモンド膜の平均膜厚：
工具基体表面に被覆するダイヤモンド膜は、その厚さが３μｍ未満では、長期の使用に亘って十分な耐摩耗性を発揮することができず、一方、ダイヤモンド膜厚が３０μｍを超えると、加工精度が低下することから、ダイヤモンド膜の平均膜厚は、３〜３０μｍと定めた。
Average film thickness of diamond film:
The diamond film coated on the surface of the tool base cannot exhibit sufficient wear resistance over a long period of use if the thickness is less than 3 μm, whereas if the diamond film thickness exceeds 30 μm, the processing accuracy The average film thickness of the diamond film was determined to be 3 to 30 μm.
結合相一部除去領域：
図１に示すように、本発明のダイヤモンド被覆工具は、工具基体の表面近傍の結合相の一部を化学的なエッチング（例えば、硫酸＋過酸化水素）によって除去し、工具基体表面近傍に結合相の一部除去された結合相一部除去領域を形成するが、これは、工具基体表面近傍の結合相（主としてＣｏであり、Ｃｒ、Ｗ等の金属成分を固溶する）の一部を除去することによって、基体とダイヤモンド膜との付着強度を高めるためである。
しかし、結合相一部除去領域の除去深さが８μｍを超えると、工具基体表面から多量の結合相成分が除去されることによって超硬合金の靭性低下が大きくなり、その結果、耐チッピング性が低下する。
したがって、図１に示すように、結合相一部除去領域の深さは、工具基体内部方向へ最大８μｍと定めた。
なお、結合相一部除去領域の深さが１μｍ未満であると、残留している結合相中のＣｏの影響が依然として大きく、ダイヤモンド膜の耐剥離性向上が十分でないため、結合相一部除去領域の深さは工具基体内部方向へ少なくとも１μｍ以上であることが望ましい。
Bond phase partial removal region:
As shown in FIG. 1, the diamond-coated tool of the present invention removes a part of the binder phase in the vicinity of the surface of the tool base by chemical etching (for example, sulfuric acid + hydrogen peroxide) and binds in the vicinity of the tool base surface. A part of the binder phase from which a part of the phase is removed is formed. This is because a part of the binder phase in the vicinity of the surface of the tool base (mainly Co, which dissolves metal components such as Cr and W) is partially formed. This is because the adhesion strength between the substrate and the diamond film is increased by removing.
However, if the removal depth of the binder phase partial removal region exceeds 8 μm, a large amount of binder phase components are removed from the surface of the tool base, resulting in a large reduction in toughness of the cemented carbide. As a result, chipping resistance is improved. descend.
Therefore, as shown in FIG. 1, the depth of the binder phase partial removal region is set to 8 μm at the maximum in the tool base internal direction.
In addition, if the depth of the binder phase partial removal region is less than 1 μm, the influence of Co in the residual binder phase is still large, and the peeling resistance of the diamond film is not sufficiently improved. It is desirable that the depth of the region is at least 1 μm or more in the direction of the inside of the tool base.
本発明のダイヤモンド被覆工具の工具基体は、ダイヤモンド膜の耐剥離性向上のために工具基体表面近傍の結合相を一部除去し、結合相一部除去領域を形成したとしても、結合相一部除去領域におけるＷＣ粒子近傍の結合相中のＣｒ濃度、Ｗ濃度を濃化させることにより、結合相とＷＣ粒子の界面における密着強度を高めることにより、工具基体の靱性低下を防止することができる。すなわち、ダイヤモンド膜の耐剥離性を向上させると同時に、工具基体の靱性低下防止を図ることができる。 The tool base of the diamond-coated tool according to the present invention has a part of the binder phase even if a part of the binder phase in the vicinity of the tool base surface is removed to form a part of the binder phase removal area in order to improve the peeling resistance of the diamond film. By increasing the Cr concentration and W concentration in the binder phase in the vicinity of the WC particles in the removal region, the adhesion strength at the interface between the binder phase and the WC particles is increased, thereby preventing the toughness of the tool base from being lowered. That is, it is possible to improve the peeling resistance of the diamond film and prevent the toughness of the tool base from being lowered.
工具基体表面近傍のＷＣ粒子界面に形成される残留結合相：
本発明のダイヤモンド被覆工具を後記する製造方法で製造した場合、図２(図１の部分拡大図に相当)に示すように、工具の刃先先端から１００μｍを超えない領域の逃げ面の垂直断面について観察し、結合相一部除去領域内のＷＣ粒子同士およびＷＣ粒子と他の炭化物との接合界面を除くＷＣ粒子の粒界には、エッチングによって除去されなかった残留結合相がほぼ１０〜３００ｎｍの厚さで残留形成される。ここで、１０ｎｍ未満の厚さの残留結合相は、後述するような測定方法で測定しようとした場合、測定することが難しく、しかも、１０ｎｍ未満の薄い残留結合相では、工具基体の強度低下、靱性低下抑制作用が十分でない。一方、工具基体表面近傍のＷＣ粒子の粒界に３００ｎｍを超える厚さの残留結合相が存在する場合には、工具基体表面に被覆形成するダイヤモンド膜との密着性が低下する。
したがって、結合相一部除去領域内のＷＣ粒子同士およびＷＣ粒子と他の炭化物との接合界面を除くＷＣ粒子の粒界に残留して形成される残留結合相の厚さは、１０〜３００ｎｍとする。
Residual bonded phase formed at the WC particle interface near the tool substrate surface:
When the diamond-coated tool of the present invention is manufactured by the manufacturing method described later, as shown in FIG. 2 (corresponding to a partially enlarged view of FIG. 1), the vertical cross section of the flank in the region not exceeding 100 μm from the tip of the tool edge. Observed, the WC particles in the partial removal region of the binder phase and the grain boundaries of the WC particles excluding the bonded interface between the WC particles and other carbides have a residual binder phase of approximately 10 to 300 nm that has not been removed by etching. Residually formed in thickness. Here, the residual bonded phase having a thickness of less than 10 nm is difficult to measure when trying to measure by a measurement method as described below, and the thin residual bonded phase of less than 10 nm reduces the strength of the tool substrate. Insufficient toughness-inhibiting action. On the other hand, when a residual bonded phase having a thickness exceeding 300 nm exists at the grain boundary of the WC particles in the vicinity of the tool base surface, the adhesion to the diamond film to be formed on the tool base surface is lowered.
Therefore, the thickness of the residual binder phase formed to remain at the grain boundaries of the WC particles excluding the WC particles in the binder phase partial removal region and the bonded interface between the WC particles and other carbides is 10 to 300 nm. To do.
また、本発明のダイヤモンド被覆工具において、前記残留結合相が形成されるＷＣ粒子の粒界長は、刃先近傍（刃先先端から１００μｍを超えない領域）の逃げ面の垂直断面についての観察において、前記結合相一部除去領域内のＷＣ粒子同士およびＷＣ粒子と他の炭化物との接合界面を除くＷＣ粒子の全粒界長の５０％以上の長さ割合であることが必要である。
残留結合相が形成されるＷＣ粒子の粒界長が５０％未満である場合には、結合相一部除去領域における残留結合相とＷＣ粒子の界面における付着強度が十分でなく、その結果、工具基体の靱性、刃先強度が低下するからである。
Further, in the diamond-coated tool of the present invention, the grain boundary length of the WC particles in which the residual binder phase is formed is the observation of the vertical cross section of the flank in the vicinity of the cutting edge (the region not exceeding 100 μm from the cutting edge tip). It is necessary that the length ratio is 50% or more of the total grain boundary length of the WC particles excluding the bonded interfaces between the WC particles in the partial removal region of the binder phase and the WC particles and other carbides.
When the grain boundary length of the WC particles in which the residual binder phase is formed is less than 50%, the adhesion strength at the interface between the residual binder phase and the WC particles in the binder phase partial removal region is not sufficient, and as a result, the tool This is because the toughness of the substrate and the strength of the cutting edge are lowered.
残留結合相におけるＣｒのＣｏに対する質量比、ＷのＣｏに対する質量比：
本発明のダイヤモンド被覆工具を後記する製造方法で製造した場合、残留結合相には、Ｃｒ、Ｗ等が固溶し、濃化して存在するが、残留結合相に固溶含有されるＣｒのＣｏに対する質量比が、０．０２未満では、結合相一部除去領域を形成するためのエッチング処理において、オーバーエッチングが生じ、ＷＣ粒子−ＷＣ粒子間のネッキング強度が低下するため、刃先の強度、靱性を確保することができない。一方、ＣｒのＣｏに対する質量比が、０．１５を超えると、ＷＣ粒子と残留結合相間の密着強度が低下するため、刃先の強度、靱性を確保することができない。
したがって、残留結合相において固溶含有されるＣｒのＣｏに対する質量比は、０．０２以上０．１５以下と定めた。
また、残留結合相に固溶含有されるＷのＣｏに対する質量比が、０．０８未満では、ＷＣ粒子と残留結合相間の密着強度が低下するため、刃先の靱性を維持することができず、一方、ＷのＣｏに対する質量比が、０．２０を超えると、残留結合相自体の強度が低下する。
したがって、残留結合相において固溶含有されるＷのＣｏに対する質量比は、０．０８以上０．２０以下と定めた。
残留結合相に固溶含有されるＯのＣｏに対する質量比が、０．０２未満では、結合相に含まれるＯが少ないため、エッチングによる結合相の過剰な除去を防ぐことができない。一方、ＯのＣｏに対する質量比が、０．０８を越えるとエッチングの進行が極度に遅くなるため、結合相の除去が進まない。
したがって、残留結合相において固溶含有されるＯのＣｏに対する質量比は、０．０２以上０．０８以下と定めた。
Mass ratio of Cr to Co and W to Co in the residual bonded phase:
When the diamond-coated tool of the present invention is manufactured by the manufacturing method described later, Cr, W, etc. are present in the residual binder phase as a solid solution and concentrated, but the Co of Cr contained in the residual binder phase as a solid solution. If the mass ratio with respect to is less than 0.02, overetching occurs in the etching process for forming the binder phase partial removal region, and the necking strength between the WC particles and the WC particles decreases, so the strength and toughness of the blade edge Can not be secured. On the other hand, when the mass ratio of Cr to Co exceeds 0.15, the adhesion strength between the WC particles and the residual binder phase is lowered, so that the strength and toughness of the blade edge cannot be ensured.
Therefore, the mass ratio of Cr to Co contained in the residual binder phase with respect to Co is determined to be 0.02 or more and 0.15 or less.
In addition, if the mass ratio of W to Co contained in the residual binder phase is less than 0.08, the adhesion strength between the WC particles and the residual binder phase decreases, so the toughness of the cutting edge cannot be maintained, On the other hand, when the mass ratio of W to Co exceeds 0.20, the strength of the residual bonded phase itself decreases.
Therefore, the mass ratio of W to Co contained in the residual binder phase is determined to be 0.08 or more and 0.20 or less.
If the mass ratio of O contained in the residual binder phase to Co is less than 0.02, the amount of O contained in the binder phase is small, so that excessive removal of the binder phase by etching cannot be prevented. On the other hand, if the mass ratio of O to Co exceeds 0.08, the progress of etching becomes extremely slow, and the removal of the binder phase does not proceed.
Therefore, the mass ratio of O to Co contained in the residual binder phase is set to 0.02 or more and 0.08 or less.
ダイヤモンド被覆工具の製造：
本発明のダイヤモンド被覆工具、例えば、ダイヤモンド被覆ＷＣ基超硬合金製ドリル、は、以下の工程（ａ）〜（ｅ）で作製することができる。
（ａ）まず、所定の平均粒径(例えば、０．５〜３μｍ)を有するＷＣ粉末、Ｃｏ粉末、Ｃｒ３Ｃ２粉末、ＶＣ粉末等を所定の成分組成になるように配合して原料粉末を作製する。
ここで、焼結後の結合相のＣｏ中に、Ｗを固溶させやすくし、結合相中にＣｒおよびＷの固溶量を増加させ、ＷＣ粒子との密着強度を高めるために、原料粉末の一つであるＷＣ粉末については、Ｃの含有割合が少ない、即ち、ＣのＷに対する組成比(ただし、原子比)が１以下のＷＣ粉末を使用することが望ましい。
（ｂ）ついで、前記原料粉末にバインダーと溶剤を加えて混合・乾燥し、成形体を作製し、１Ｐａ真空雰囲気中、１３８０〜１５００℃の温度で１〜２時間保持し、その後、５００℃まで２０℃／ｍｉｎの冷却速度で冷却後、８００℃で１５〜２０時間維持し、さらに、５００℃まで１Ｐａ真空雰囲気中２０℃／ｍｉｎの冷却速度で冷却し、５００℃〜室温まで大気中雰囲気にて２０℃／ｍｉｎの冷却速度で冷却を行うことによって、ＷＣ基超硬合金焼結体を作製し、これを、所定の形状に加工することで工具基体を作製する。
ここで、上記８００℃にて長時間保持することによって、結合相中のＣｒとＷの固溶濃度を高める。さらに大気雰囲気にて冷却することにより、結合相が酸素を含むことで耐食性を向上させ、結合相のエッチング抵抗性を高め、オーバーエッチング防止と、エッチング後の結合相一部除去領域に形成される残留結合相とＷＣ粒子の密着強度を高める。
なお、オーバーエッチングを防止し、所定深さの結合相一部除去領域を形成するという観点からは、上記大気雰囲気時の冷却開始温度を５００℃以下にすることが望ましい。
（ｃ）ついで、前記工具基体を、希塩酸（０．５％）と過酸化水素（３％）の酸混合溶液１Ｌに８〜１５秒間、室温（２３℃）で浸漬し、工具基体の表面近傍のＣｏを主成分とする結合相の一部をエッチングで除去する。
さらに、これらの工具基体を、４５±５℃に維持された村上試薬（フェリシアンカリウム（１０ｇ）と水酸化カリウム（１０ｇ）とイオン交換水（１００ｇ）の混合溶液）にて３０〜６０分間処理し、次いで、酸により、工具基体表面のＣｏを除去することにより、所定の深さの結合相一部除去領域を形成する。
（ｄ）ついで、前記工具基体を、イソプロピルアルコールにダイヤモンド粉末と界面活性剤を添加した溶液で超音波処理する。
（ｅ）ついで、前記工具基体を、熱フィラメントＣＶＤ装置に装入し、フィラメント温度を２１００〜２２００℃、水素ガスとメタンガスを１００：１の流量比で流しながら、全圧：７００Ｐａ、工具基体温度を９００℃に維持し、３〜３０μｍの膜厚のダイヤモンド膜を成膜する。
Production of diamond coated tools:
The diamond-coated tool of the present invention, for example, a diamond-coated WC-based cemented carbide drill, can be produced by the following steps (a) to (e).
(A) First, WC powder, Co powder, Cr 3 C 2 powder, VC powder and the like having a predetermined average particle size (for example, 0.5 to 3 μm) are blended so as to have a predetermined component composition, and raw material powder Is made.
Here, in order to facilitate solid solution of W in the binder phase Co after sintering, to increase the solid solution amount of Cr and W in the binder phase, and to increase the adhesion strength with the WC particles, the raw material powder As for the WC powder that is one of the above, it is desirable to use a WC powder having a small C content, that is, a composition ratio of C to W (atomic ratio) of 1 or less.
(B) Next, a binder and a solvent are added to the raw material powder and mixed and dried to prepare a molded body, which is held in a 1 Pa vacuum atmosphere at a temperature of 1380 to 1500 ° C. for 1 to 2 hours, and then to 500 ° C. After cooling at a cooling rate of 20 ° C./min, the temperature is maintained at 800 ° C. for 15 to 20 hours, and further cooled to 500 ° C. in a 1 Pa vacuum atmosphere at a cooling rate of 20 ° C./min. By cooling at a cooling rate of 20 ° C./min, a WC-based cemented carbide sintered body is produced, and a tool base is produced by processing this into a predetermined shape.
Here, the solid solution concentration of Cr and W in the binder phase is increased by holding at 800 ° C. for a long time. Further, by cooling in the air atmosphere, the bonding phase contains oxygen, thereby improving the corrosion resistance, increasing the etching resistance of the bonding phase, preventing over-etching, and forming in the bonded phase partial removal region after etching. Increase adhesion strength between residual binder phase and WC particles.
Note that, from the viewpoint of preventing over-etching and forming a partial removal region of the binder phase having a predetermined depth, it is desirable to set the cooling start temperature in the air atmosphere to 500 ° C. or lower.
(C) Next, the tool base is immersed in 1 L of an acid mixed solution of dilute hydrochloric acid (0.5%) and hydrogen peroxide (3%) at room temperature (23 ° C.) for 8 to 15 seconds, and near the surface of the tool base. A part of the binder phase mainly containing Co is removed by etching.
Further, these tool substrates were treated with Murakami's reagent (mixed solution of potassium ferricyan (10 g), potassium hydroxide (10 g) and ion-exchanged water (100 g)) maintained at 45 ± 5 ° C. for 30 to 60 minutes. Subsequently, Co on the surface of the tool base is removed with an acid to form a bonded phase partial removal region having a predetermined depth.
(D) Next, the tool base is subjected to ultrasonic treatment with a solution obtained by adding diamond powder and a surfactant to isopropyl alcohol.
(E) Next, the tool base is charged into a hot filament CVD apparatus, and the total pressure is 700 Pa and the tool base temperature while the filament temperature is 2100 to 2200 ° C. and hydrogen gas and methane gas are flowed at a flow rate ratio of 100: 1. Is maintained at 900 ° C., and a diamond film having a thickness of 3 to 30 μm is formed.
本発明のダイヤモンド被覆工具の製造においては、原料粉末としてＣの含有割合の少ないＷＣ粉末の使用（前記工程（ａ））、さらに、８００℃での長時間保持による結合相へのＣｒとＷの固溶量のさらなる濃化と結合相が酸素を含むこと（前記工程（ｂ））により、結合相のエッチング抵抗性が高められ、所定深さの結合相一部除去領域の形成とともに、所定の厚さと所定のＷＣ粒界長割合の残留結合相を形成することができる。
その結果、工具基体表面からエッチングによりＣｏを除去し、結合相一部除去領域を形成してダイヤモンド膜と工具基体の密着性を改善した場合でも、結合相一部除去領域における残留結合相とＷＣ粒子との密着強度が高いため、刃先の強度、靱性を向上させることができ、ダイヤモンド被覆工具のすぐれた耐チッピング性が発揮される。
In the production of the diamond-coated tool of the present invention, the use of WC powder with a low C content as a raw material powder (the step (a)), and Cr and W in the binder phase by holding at 800 ° C. for a long time. By further increasing the amount of the solid solution and containing the oxygen in the binder phase (the step (b)), the etching resistance of the binder phase is improved, and the binder phase partial removal region having a predetermined depth is formed. A residual binder phase having a thickness and a predetermined WC grain boundary length ratio can be formed.
As a result, even when Co is removed from the surface of the tool base by etching and a bond phase partial removal region is formed to improve the adhesion between the diamond film and the tool base, the residual bond phase and WC in the bond phase partial removal region are improved. Since the adhesion strength with the particles is high, the strength and toughness of the cutting edge can be improved, and the excellent chipping resistance of the diamond-coated tool is exhibited.
本発明のダイヤモンド被覆超硬合金製切削工具は、ＷＣと３〜１５質量％のＣｏを主成分とし、さらに、少なくとも０．１〜３質量％のＣｒを含有するＷＣ基超硬合金からなる工具基体にダイヤモンド膜を被覆形成したダイヤモンド被覆超硬合金製切削工具であって、ダイヤモンド膜が３〜３０μｍの平均膜厚を有し、ＷＣ基超硬合金からなる工具基体とダイヤモンド膜の界面から工具基体内部方向へ最大８μｍの深さにおいて結合相の一部がエッチング等によって除去された結合相一部除去領域を有し、工具の刃先近傍の逃げ面の垂直断面における観察で結合相一部除去領域内のＷＣ粒同士およびＷＣ粒と他の炭化物との接合粒界を除くＷＣ粒界に１０〜３００ｎｍの厚みの残留結合相がＷＣ粒界長の５０％以上の割合で存在し、ＷＣ粒界に存在する残留結合相におけるＣｒのＣｏに対する質量比が０．０２以上０．１５以下、ＷのＣｏに対する質量比が０．０８以上０．２０以下、ＯのＣｏに対する質量比が、０．０２以上０．０８以下であることによって、工具基体とダイヤモンド膜との密着性を向上させるとともに刃先強度・靱性を向上させたものであって、ＣＦＲＰなどの難削材の切削加工において、すぐれた耐チッピング性を示し、長期の使用にわたってすぐれた耐摩耗性を発揮する。 The diamond-coated cemented carbide cutting tool of the present invention is a tool made of a WC-based cemented carbide containing WC and 3 to 15% by mass of Co, and further containing at least 0.1 to 3% by mass of Cr. A diamond-coated cemented carbide cutting tool in which a diamond film is formed on a substrate, the diamond film having an average film thickness of 3 to 30 μm, and the tool from the interface between the tool substrate and the diamond film made of a WC-based cemented carbide Part of the binder phase is removed by etching etc. at a maximum depth of 8 μm in the internal direction of the substrate. Part of the binder phase is removed by observation in the vertical section of the flank near the cutting edge of the tool. A residual bonded phase having a thickness of 10 to 300 nm exists at a ratio of 50% or more of the WC grain boundary length at the WC grain boundaries excluding the joint grain boundaries between the WC grains and other carbides in the region. To the world The mass ratio of Cr to Co in the residual bonded phase present is 0.02 to 0.15, the mass ratio of W to Co is 0.08 to 0.20, and the mass ratio of O to Co is 0.02 or more. By being 0.08 or less, the adhesion between the tool base and the diamond film is improved and the strength and toughness of the cutting edge are improved. Excellent chipping resistance in cutting difficult-to-cut materials such as CFRP Show excellent wear resistance over long-term use.
本発明のダイヤモンド被覆工具について、実施例により具体的に説明する。
なお、ここでは、ダイヤモンド被覆工具の具体例としてダイヤモンド被覆超硬合金製ドリルについて述べるが、本発明はこれに限られるものではなく、ダイヤモンド被覆超硬合金製インサート、ダイヤモンド被覆超硬合金製エンドミル等、各種のダイヤモンド被覆工具に適用できるものである。
The diamond-coated tool of the present invention will be specifically described with reference to examples.
Here, although a diamond-coated cemented carbide drill is described as a specific example of the diamond-coated tool, the present invention is not limited to this, but a diamond-coated cemented carbide insert, a diamond-coated cemented carbide end mill, etc. It can be applied to various diamond-coated tools.
（ａ）原料粉末として、いずれも０．５〜２μｍの範囲内の所定の平均粒径を有するＷＣ粉末、Ｃｏ粉末、Ｃｒ３Ｃ２粉末、ＴａＣ粉末、ＮｂＣ粉末、ＴｉＣ粉末、ＶＣ粉末およびＺｒＣ粉末を、表１に示される割合に配合し、さらにバインダーと溶剤を加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、いずれも１００ＭＰａの圧力でプレス成形して、直径が１０ｍｍの丸棒圧粉体とし、これらの丸棒圧粉体を、表２、表３に示す条件で焼結、冷却すること、即ち、１Ｐａの真空雰囲気中、１３８０〜１５００℃の温度で１〜２時間保持（表２の焼結条件参照）後、５００℃まで２０℃／ｍｉｎの冷却速度で冷却し（表２の冷却条件１参照）、その後、８００℃にて１５〜２０時間維持し（表２の焼鈍条件参照）、８００から５００℃〜４５０℃までの間を１Ｐａの真空雰囲気にて２０℃／ｍｉｎの冷却速度で冷却し（表３の冷却条件２参照）、さらに、５００℃〜４５０℃から室温まで大気雰囲気にて２０℃／ｍｉｎの冷却速度で冷却を行う（表３の冷却条件３参照）ことによって、ＷＣ基超硬合金焼結体を作製し、これを、所定の形状に加工することで工具基体を作製する。焼結体を作製した後、該焼結体を研磨加工することにより、本発明ＷＣ基超硬合金焼結体（以下、単に「本発明焼結体」という）１〜６を製造した。
なお、原料粉末である上記ＷＣ粉末は、その組成をＷＣｘと表現した場合、ｘの値（なお、ｘは、原子比）はいずれも１以下であり、表１にｘの具体的数値を併記する。
ついで、前記本発明焼結体１〜６を、溝形成部の外径寸法が８ｍｍとなるように研削加工することにより、ＷＣ基超硬合金からなる本発明ドリル用工具基体（以下、単に「本発明ドリル基体」という）１〜６を製造した。
(A) WC powder, Co powder, Cr 3 C 2 powder, TaC powder, NbC powder, TiC powder, VC powder, and ZrC, all having a predetermined average particle diameter in the range of 0.5 to 2 μm as raw material powder The powder was blended in the proportions shown in Table 1, and after further adding a binder and a solvent, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then press-molded at a pressure of 100 MPa. Sintering and cooling these round bar compacts under the conditions shown in Table 2 and Table 3, ie, 1 to 2 hours at a temperature of 1380 to 1500 ° C. in a vacuum atmosphere of 1 Pa. After holding (see the sintering conditions in Table 2), cooling to 500 ° C. at a cooling rate of 20 ° C./min (see cooling conditions 1 in Table 2), and then maintaining at 800 ° C. for 15 to 20 hours (Table 2). 800), 800 From 500 ° C. to 450 ° C. in a 1 Pa vacuum atmosphere at a cooling rate of 20 ° C./min (see cooling condition 2 in Table 3), and from 500 ° C. to 450 ° C. to room temperature in an air atmosphere By cooling at a cooling rate of 20 ° C./min (see cooling condition 3 in Table 3), a WC-based cemented carbide sintered body is produced, and a tool base is produced by processing this into a predetermined shape. To do. After the sintered body was produced, the sintered body was polished to produce the inventive WC-based cemented carbide sintered bodies (hereinafter simply referred to as “the inventive sintered body”) 1 to 6.
In addition, when the composition of the WC powder as the raw material powder is expressed as WCx, the value of x (where x is an atomic ratio) is 1 or less, and Table 1 also includes specific numerical values of x. To do.
Next, by grinding the sintered bodies 1 to 6 of the present invention so that the outer diameter of the groove forming portion is 8 mm, the tool base for a drill of the present invention made of a WC-based cemented carbide (hereinafter simply referred to as “ 1 to 6) were produced.
（ｂ）ついで、前記本発明ドリル基体１〜６を、硫酸と過酸化水素と水を２：１：１００（容積比）で混合したエッチング液に３〜１０秒浸漬して、ドリル基体１〜６の表面近傍のＣｏを主成分とする結合相の一部をエッチングで除去する。 (B) Next, the drill bases 1 to 6 of the present invention are immersed in an etching solution in which sulfuric acid, hydrogen peroxide and water are mixed at a ratio of 2: 1: 100 (volume ratio) for 3 to 10 seconds. A part of the binder phase mainly containing Co in the vicinity of the surface of 6 is removed by etching.
（ｃ）さらに、本発明ドリル基体１〜６を、４５±５℃に維持された村上試薬（フェリシアンカリウム（１０ｇ）と水酸化カリウム（１０ｇ）とイオン交換水（１００ｇ）の混合溶液）にて工具基体を３０〜６０分間処理し、次いで、酸により、工具基体表面のＣｏを除去することにより、結合相一部除去領域を形成する。 (C) Further, the drill bases 1 to 6 of the present invention were placed in a Murakami reagent (mixed solution of potassium ferricyan (10 g), potassium hydroxide (10 g) and ion-exchanged water (100 g)) maintained at 45 ± 5 ° C. Then, the tool base is treated for 30 to 60 minutes, and then Co is removed from the surface of the tool base with an acid to form a binder phase partial removal region.
（ｄ）ついで、本発明ドリル基体１〜６を、イソプロピルアルコールにダイヤモンド粉末と界面活性剤を添加した溶液で超音波処理する。 (D) Next, the drill bases 1 to 6 of the present invention are ultrasonically treated with a solution obtained by adding diamond powder and a surfactant to isopropyl alcohol.
（ｅ）ついで、本発明ドリル基体１〜６を、熱フィラメントＣＶＤ装置に装入し、フィラメント温度を２１００〜２２００℃、水素ガスとメタンガスを１００：１の流量比で流しながら、全圧：７００Ｐａ、工具基体温度を９００℃に維持して、ダイヤモンド膜を成膜する。
前記製造工程により、表４に示す本発明のダイヤモンド被覆ＷＣ基超硬合金製ドリル（以下、単に、「本発明ドリル」という）１〜６を作製した。
(E) Next, the drill bases 1 to 6 of the present invention are inserted into a hot filament CVD apparatus, and the total pressure is 700 Pa while the filament temperature is 2100 to 2200 ° C. and hydrogen gas and methane gas are flowed at a flow rate ratio of 100: 1. A diamond film is formed while maintaining the tool substrate temperature at 900 ° C.
Through the manufacturing process, diamond-coated WC-based cemented carbide drills (hereinafter simply referred to as “the present invention drill”) 1 to 6 of the present invention shown in Table 4 were produced.
前記製造工程によれば、特に、工程（ａ）の低温焼鈍時の結合相へのＣｒとＷの固溶量の濃化と結合相に酸素が含まれることにより、結合相のエッチング抵抗性が高められ、オーバーエッチングの恐れがなく所定深さの結合相一部除去領域を形成し得るとともに、所定の厚さと所定のＷＣ粒界長割合の残留結合相を形成することができ、工具基体、特に、刃先の強度、靱性を向上させることができる。 According to the manufacturing process, particularly, the etching resistance of the binder phase is increased by increasing the solid solution amount of Cr and W in the binder phase during the low temperature annealing in step (a) and by including oxygen in the binder phase. A binder phase partial removal region having a predetermined depth can be formed without fear of over-etching, and a residual bonded phase having a predetermined thickness and a predetermined WC grain boundary length ratio can be formed. In particular, the strength and toughness of the cutting edge can be improved.
比較のため、表５の配合組成の原料粉末を用いて、実施例と同様に丸棒圧粉体を作製し、これを、表６、表７に示す各種の条件で焼結することにより比較例焼結体１〜１６を作製した。
なお、表５に示される原料粉末のＷＣ粉末についても、その組成をＷＣｘと表現した場合のｘの値（ｘは、原子比）を併記した。
ついで、比較例焼結体１〜１６を、溝形成部の外径寸法が８ｍｍとなるように研削加工することにより、ＷＣ基超硬合金からなる比較例ドリル用工具基体（以下、単に「比較例ドリル基体」という）１〜１６を製造した。
ついで、比較例ドリル基体１〜１６に対して、本発明ドリル基体に対して行った前記工程（ｂ）〜（ｅ）と同様にして、ダイヤモンド膜を成膜し、表８に示す比較例のダイヤモンド被覆ＷＣ基超硬合金製ドリル（以下、単に、「比較例ドリル」という）１〜１６を作製した。
For comparison, a raw material powder having the composition shown in Table 5 was used to prepare a round bar green compact in the same manner as in the Examples, and this was compared by sintering under various conditions shown in Tables 6 and 7. Example sintered bodies 1 to 16 were produced.
In addition, about the WC powder of the raw material powder shown in Table 5, the value of x (x is an atomic ratio) when the composition was expressed as WCx was written together.
Next, the comparative sintered body 1 to 16 was ground so that the outer diameter of the groove forming portion was 8 mm, whereby a comparative drill base made of a WC-based cemented carbide (hereinafter simply referred to as “Comparison”). 1 to 16) were manufactured.
Subsequently, a diamond film was formed on the comparative drill bases 1 to 16 in the same manner as the steps (b) to (e) performed on the drill base of the present invention. Diamond-coated WC-based cemented carbide drills (hereinafter simply referred to as “comparative example drills”) 1 to 16 were produced.
前記本発明ドリル１〜６および比較例ドリル１〜１６について、ドリルの刃先のダイヤモンド膜とドリル基体界面近傍をクロスセクションポリッシャーによって表面に対して垂直に断面研磨を行い、ダイヤモンド膜とドリル基体界面近傍において、結合相の一部が化学処理によって除去された領域、すなわち、結合相一部除去領域の平均深さをＤ（μｍ）とした場合、０．５Ｄ（μｍ）×０．５Ｄ（μｍ）のエリアを前記金属結合相一部除去領域内で３箇所を無作為に選定し、オージェ電子分光による元素マッピングおよび定量分析により、ＣｒとＣｏの質量比、ＷとＣｏの質量比、残留結合相の厚みおよびＷＣ粒界長に対する前記残留結合相の占有長さ割合(長さ％)を測定した。なお、測定値は３箇所の平均とした。また、結合相一部除去領域の平均深さＤについては、上記の工具の基体表面の垂直断面において、結合相の一部が除去された領域の基体端面からの長さを３点測定し、この平均値を平均深さＤとした。
また、本発明ドリル１〜６および比較例ドリル１〜１６のダイヤモンド膜の膜厚を、走査型電子顕微鏡（倍率５０００倍）を用いて測定し、観察視野内の５点の層厚を測って平均して平均膜厚を測った。
表４、表８にこれらの値を示す。
For the drills 1 to 6 of the present invention and the drills 1 to 16 of the comparative examples, the diamond film at the drill tip and the vicinity of the interface of the drill base are subjected to cross-sectional polishing perpendicular to the surface by a cross section polisher, , Where D (μm) is the area where a part of the binder phase has been removed by chemical treatment, that is, the average depth of the binder phase partially removed area is 0.5D (μm) × 0.5D (μm) 3 areas are randomly selected within the metal bonded phase partial removal region, and by element mapping and quantitative analysis by Auger electron spectroscopy, the mass ratio of Cr and Co, the mass ratio of W and Co, the residual bonded phase The ratio of the occupied length of the residual binder phase to the WC grain boundary length (length%) was measured. In addition, the measured value was made into the average of 3 places. Further, for the average depth D of the binder phase partial removal region, the length from the substrate end face of the region where the binder phase is partially removed is measured at three points in the vertical cross section of the substrate surface of the above tool. This average value was defined as an average depth D.
Moreover, the film thickness of the diamond film of this invention drills 1-6 and comparative example drills 1-16 is measured using a scanning electron microscope (magnification 5000 times), and the layer thickness of five points in the observation visual field is measured. The average film thickness was measured on average.
Tables 4 and 8 show these values.
つぎに、前記本発明ドリル１〜６および比較例ドリル１〜１６を用いて、以下の条件で、ＣＦＲＰの高速ドリル穴開け試験を行った。
切削速度：２１０ ｍ／ｍｉｎ，
送り：０．２１ ｍｍ／ｒｅｖ，
穴深さ：２５ ｍｍ(貫通穴)，
前記切削試験において、正常摩耗の場合は被削材の穴の入り口側もしくは出口側に発生するバリが０．５ｍｍを超えた時点で使用寿命とし、それまでの穴あけ加工数を測定した。
また、ドリル折損等が原因で使用寿命に至った場合には、それまでの穴あけ加工数を測定した。
表９にこれらの測定結果を示す。
Next, using the drills 1 to 6 of the present invention and the drills of comparative examples 1 to 16, a high-speed drilling test for CFRP was performed under the following conditions.
Cutting speed: 210 m / min,
Feed: 0.21 mm / rev,
Hole depth: 25 mm (through hole),
In the cutting test, in the case of normal wear, the service life was determined when the burr generated on the entrance side or the exit side of the hole of the work material exceeded 0.5 mm, and the number of drilling operations up to that time was measured.
In addition, when the service life was reached due to drill breakage or the like, the number of drilling operations so far was measured.
Table 9 shows the measurement results.
表４、８、９の結果からも明らかなように、本発明ドリル１〜６は、ダイヤモンド膜が平均膜厚３〜３０μｍの層厚を有し、工具基体とダイヤモンド膜の界面から基体内部方向へ最大８μｍの深さにおける結合相の一部が化学処理によって除去された結合相一部除去領域を有し、工具の刃先近傍（刃先先端から１００μｍを超えない領域）の逃げ面の垂直断面における観察で、結合相一部除去領域内のＷＣ粒子同士およびＷＣ粒子と他の炭化物との接合粒界を除くＷＣ粒界に１０〜３００ｎｍの厚みの残留結合相がＷＣ粒界長の５０％以上の割合で存在し、ＷＣ粒界に存在する残留結合相におけるＣｒのＣｏに対する質量比が０．０２以上０．１５以下、ＷのＣｏに対する質量比が０．０８以上０．２０以下、ＯのＣｏに対する質量比が０．０２以上０．０８以下であることから、ＣＦＲＰ等の難削材の高送りドリル穴開け切削加工において、すぐれた刃先強度を示すとともに、長期の使用に亘ってすぐれた耐チッピング性、耐摩耗性を発揮している。 As is clear from the results of Tables 4, 8, and 9, in the drills 1 to 6 of the present invention, the diamond film has an average film thickness of 3 to 30 μm, and the direction from the interface between the tool substrate and the diamond film toward the inside of the substrate In the vertical cross section of the flank in the vicinity of the cutting edge of the tool (the area not exceeding 100 μm from the tip of the cutting edge), which has a bonding phase partial removal area where a part of the bonding phase at a depth of up to 8 μm is removed by chemical treatment. By observation, a residual binder phase with a thickness of 10 to 300 nm is 50% or more of the WC grain boundary length at the WC grain boundaries excluding the joint grain boundaries between the WC grains and the WC grains and other carbides in the binder phase partial removal region. The mass ratio of Cr to Co in the residual binder phase existing at the WC grain boundary is 0.02 to 0.15, the mass ratio of W to Co is 0.08 to 0.20, The mass ratio to Co is 0.0 Since it is 0.08 or less, it exhibits excellent cutting edge strength and high chipping resistance and wear resistance over long-term use in high-feed drilling of difficult-to-cut materials such as CFRP. Demonstrating.
これに対して、本発明ドリルのような結合相一部除去領域内に所定の残留結合相を有していない比較ドリル１〜１６は、刃先強度が劣り、短期に寿命に至ることが明らかである。 On the other hand, it is clear that the comparative drills 1 to 16 that do not have the predetermined residual binder phase in the binder phase partial removal region such as the drill of the present invention have inferior cutting edge strength and reach a short life. is there.
本発明のダイヤモンド被覆超硬合金製切削工具は、ダイヤモンド被覆超硬合金製ドリルばかりでなく、ダイヤモンド被覆超硬合金製インサート、ダイヤモンド被覆超硬合金製エンドミル等、各種のダイヤモンド被覆工具に適用できるものであり、すぐれた刃先強度、耐チッピング性、耐摩耗性を発揮することから、切削加工の省エネ化、低コスト化に十分満足に対応できるものである。 The diamond-coated cemented carbide cutting tool of the present invention is applicable not only to diamond-coated cemented carbide drills but also to various diamond-coated tools such as diamond-coated cemented carbide inserts and diamond-coated cemented carbide end mills. Since it exhibits excellent cutting edge strength, chipping resistance, and wear resistance, it can sufficiently satisfy energy saving and cost reduction in cutting.
Claims (1)
前記ダイヤモンド膜は、３〜３０μｍの平均膜厚を有し、
前記炭化タングステン基超硬合金からなる工具基体とダイヤモンド膜の界面から工具基体内部方向へ最大８μｍの深さにおいて結合相の一部が除去された結合相一部除去領域が形成され、
前記工具基体の少なくとも刃先近傍の逃げ面の垂直断面においては、前記結合相一部除去領域内の炭化タングステン同士および炭化タングステンと他の炭化物との接合粒界を除く炭化タングステン粒界に、１０〜３００ｎｍの厚みの残留結合相が前記炭化タングステン粒界長の５０％以上の割合で存在し、
前記炭化タングステン粒界に存在する残留結合相におけるクロムのコバルトに対する質量比が０．０２以上０．１５以下、また、タングステンのコバルトに対する質量比が０．０８以上０．２０以下、酸素のＣｏに対する質量比が、０．０２以上０．０８以下であることを特徴とするダイヤモンド被覆超硬合金製切削工具。 A diamond-coated ultra-coating comprising a tungsten carbide-based cemented carbide comprising tungsten carbide and 3 to 15% by mass of cobalt and further comprising at least 0.1 to 3% by mass of chromium and coated with a diamond film. A hard alloy cutting tool,
The diamond film has an average film thickness of 3 to 30 μm,
A binder phase partial removal region is formed in which a part of the binder phase is removed at a depth of 8 μm at the maximum from the interface between the tool base and the diamond film made of the tungsten carbide base cemented carbide to the inside of the tool base,
In the vertical cross section of the flank at least near the cutting edge of the tool base, the tungsten carbide grain boundaries excluding the joint grains between tungsten carbides and tungsten carbide and other carbides in the binder phase partial removal region are 10 to 10. A residual binder phase having a thickness of 300 nm is present in a proportion of 50% or more of the tungsten carbide grain boundary length;
The mass ratio of chromium to cobalt in the residual bonded phase present at the tungsten carbide grain boundary is 0.02 to 0.15, and the mass ratio of tungsten to cobalt is 0.08 to 0.20. Oxygen to Co A diamond-coated cemented carbide cutting tool having a mass ratio of 0.02 to 0.08.
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