JP2005226103A - Fine-grained cemented carbide - Google Patents
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- JP2005226103A JP2005226103A JP2004034517A JP2004034517A JP2005226103A JP 2005226103 A JP2005226103 A JP 2005226103A JP 2004034517 A JP2004034517 A JP 2004034517A JP 2004034517 A JP2004034517 A JP 2004034517A JP 2005226103 A JP2005226103 A JP 2005226103A
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本願発明は、炭化タングステン基超硬合金に関し、硬質分散相の平均粒径が０．９μｍ以下の粒子を有する微粒超硬合金である。 The present invention relates to a tungsten carbide based cemented carbide, which is a fine cemented carbide having particles with an average particle size of a hard dispersed phase of 0.9 μm or less.
平均粒径が１μｍ以下のＷＣ硬質分散相を含有する微粒超硬合金は、硬さとともに靭性も高いため小径エンドミル、小径ドリル、各種剪断刃などに広範囲に用いられている。近年、微細加工品の増加とともに、エンドミルやドリルの小径化が急速に進み、微粒合金の平均粒径が益々小さくなり、しかも硬度と靭性の高いものが要求されてきている。そのため、焼結中におけるＷＣ硬質分散相の粒成長を抑制するため、Ｖ、Ｃｒ、Ｔａなどの金属、もしくはそれらの炭化物、窒化物、炭窒化物などの化合物を、ＷＣに対する粒成長抑制材として用いることが提案されている。これらの具体的な例として、特許文献１〜３が開示されている。
特許文献１は、ＶとＣｒとを複合添加することにより、合金の靭性低下の原因となる第３相が生じる程多量のＶやＣｒを添加せず、真空焼結後に１００ＭＰａのＡｒ雰囲気中でＨＩＰ処理することにより、ＶやＣｒが結合相中に固溶しており本質的にＷＣ相と結合相の２相からなり、しかもＷＣの平均粒径が０．７μｍ以下である超硬合金が開示されている。
特許文献２は、ＶとＣｒの２種を添加し、真空雰囲気焼結後に５．９ＭＰａで加圧焼結し、急冷することにより、ＷＣをＶとＷとＣｒの析出複合炭化物の薄層で被覆し、結合相中に（Ｖ、Ｗ、Ｃｒ）Ｃの析出を無くすことにより、一段と強度の高い超硬合金が開示されている。
特許文献３は、真空雰囲気焼結後に４．９〜１４．７ＭＰａで加圧焼結し、５０〜１００℃／分で急冷することにより、Ｃｏを主体とする結合相中にＶとＷとＣｒの析出複合炭化物からなる硬質分散相を微細に分散分布させるとともに、ＷＣをＶとＷとＣｒの析出複合炭化物の薄層で被覆することにより、一段と高い強度をもつ超硬合金が開示されている。しかしながら、特許文献１〜３に開示されている従来技術では、結合相中にＶやＣｒ、Ｗが固溶されているが、ＴａやＭｏ等が固溶されておらず、結合相の硬度や耐熱性が劣る欠点がある。即ち、例えば、プリント基板等の回路の高密度化と低価格化が進展するにつれて、小径ドリルによる穴あけ作業はますます高速・高効率化がなされ、ドリルと被削材間の摩擦熱によりドリル自体にかかる温度が高くなっていく傾向にあるにもかかわらず、高温において硬度と靭性とが低下し、摩耗や折損のためにより早い段階で寿命に達してしまう欠点がある。このため、例えば、プリント基板穴あけようの小径ドリル等に用いた場合、微小チッピングや折損のためにより早い段階で寿命に達してしまう欠点がある。
A fine cemented carbide containing a WC hard dispersed phase having an average particle diameter of 1 μm or less is widely used in small diameter end mills, small diameter drills, various shearing blades and the like because of its high hardness and toughness. In recent years, with the increase in finely processed products, the diameter of end mills and drills has been rapidly reduced, and the average particle size of the fine-grained alloy has become smaller and higher in hardness and toughness. Therefore, in order to suppress grain growth of the WC hard dispersed phase during sintering, metals such as V, Cr, Ta, or compounds such as carbides, nitrides, carbonitrides thereof are used as grain growth inhibitors for WC. It has been proposed to use. As specific examples, Patent Documents 1 to 3 are disclosed.
In Patent Document 1, by adding V and Cr in combination, a large amount of V or Cr is not added so that a third phase that causes a reduction in the toughness of the alloy is generated, and in a 100 MPa Ar atmosphere after vacuum sintering. By performing the HIP treatment, a cemented carbide having V and Cr dissolved in the binder phase and essentially consisting of two phases, ie, a WC phase and a binder phase, and having an average WC grain size of 0.7 μm or less is obtained. It is disclosed.
In Patent Document 2, two types of V and Cr are added, pressure sintering is performed at 5.9 MPa after vacuum atmosphere sintering, and quenching is performed, whereby WC is a thin layer of precipitated composite carbide of V, W, and Cr. A cemented carbide with higher strength is disclosed by coating and eliminating the precipitation of (V, W, Cr) C in the binder phase.
In Patent Document 3, pressure sintering is performed at 4.9 to 14.7 MPa after vacuum atmosphere sintering, and rapid cooling is performed at 50 to 100 ° C./min, whereby V, W, and Cr are contained in a binder phase mainly composed of Co. A cemented carbide having a much higher strength is disclosed by finely dispersing and dispersing a hard dispersed phase composed of the precipitated composite carbide of WC and coating WC with a thin layer of the precipitated composite carbide of V, W and Cr. . However, in the prior art disclosed in Patent Documents 1 to 3, V, Cr, and W are dissolved in the binder phase, but Ta and Mo are not dissolved, and the hardness of the binder phase is low. There is a disadvantage that heat resistance is inferior. That is, for example, as the circuit density of printed circuit boards and the like increases, drilling work with small-diameter drills becomes faster and more efficient, and the drill itself due to frictional heat between the drill and the work material. In spite of the tendency for the temperature to increase, the hardness and toughness decrease at high temperatures, and there is a drawback that the life is reached at an earlier stage due to wear and breakage. For this reason, for example, when used for a small-diameter drill for drilling a printed circuit board, there is a drawback that the life is reached at an earlier stage due to minute chipping or breakage.
本発明が解決しようとする課題は、Ｃｏが主成分である結合相において、その硬度と耐熱性とを飛躍的に高め、高温においても優れた硬度と靭性とを有する微粒超硬合金を提供することである。 The problem to be solved by the present invention is to provide a fine cemented carbide having a hardness and heat resistance dramatically improved in a binder phase mainly composed of Co and having excellent hardness and toughness even at a high temperature. That is.
本発明は、Ｃｏ含有量が２〜１３質量％である炭化タングステン基超硬合金であり、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１．５〜１２質量％含有し、Ｃｒとラーベス相ＡＣｒ2を作る元素Ａが少なくとも１種類以上含有し、結合相中の元素Ａ含有量の総和が、結合相中のＣｒ含有量に対して３〜２５原子％であることを特徴とする微粒超硬合金である。上記の構成を採用することにより、原子半径が大きく異なるＣｒと元素Ａとを組み合わせて結合相中に安定して含有させることができる。その結果、サイズ効果によって結合相内に歪みを生じさせ、結合相自体の硬度と耐熱性とを大幅に改善できるようになり、高温においても優れた硬度と靭性とを有する微粒超硬合金が実現できる。本発明の微粒超硬合金は、炭化タングステン基超硬合金の硬質分散相の平均粒径が０．９μｍ以下であり、元素ＡがＴａ及び／又はＮｂであることが好ましい。また、結合相中のＣｒに対するＭｏ含有量が１〜１０原子％であることが好ましい。更に、結合相中のＣｒに対するＹ及び／又は希土類元素の含有量が０．０５〜０．２原子％であることが好ましい。 The present invention is a tungsten carbide-based cemented carbide with a Co content of 2 to 13% by mass, and a binder phase mainly composed of Co contains a Cr content of 1.5 to 12% by mass with respect to Co. And at least one element A that forms Laves phase ACr 2, and the total content of element A in the binder phase is 3 to 25 atomic% with respect to the Cr content in the binder phase. It is a fine cemented carbide. By adopting the above configuration, it is possible to stably combine Cr and the element A in which the atomic radii are greatly different in the binder phase. As a result, distortion occurs in the binder phase due to the size effect, and the hardness and heat resistance of the binder phase itself can be greatly improved, resulting in a fine cemented carbide with excellent hardness and toughness even at high temperatures. it can. In the fine cemented carbide of the present invention, the average particle size of the hard dispersed phase of the tungsten carbide-based cemented carbide is preferably 0.9 μm or less, and the element A is preferably Ta and / or Nb. Moreover, it is preferable that Mo content with respect to Cr in a binder phase is 1-10 atomic%. Furthermore, it is preferable that the content of Y and / or rare earth elements with respect to Cr in the binder phase is 0.05 to 0.2 atomic%.
靭性が高く、主にＣｏからなる結合相中に、Ｃｒ及びＣｒとラーベス相ＡＣｒ２を作る元素Ａを少なくとも１種類以上含有させることにより、原子半径が大きく異なるＣｒと元素Ａとを同時に安定して結合相中に含有させ、サイズ効果により結合相内に歪みを生じさせ、結合相自体の硬度と耐熱性とが大幅に改善できるようになり、高温においても優れた硬度と靭性とを有する微粒超硬合金材が実現できる。この結果、例えば、小径ドリル等に適用して、刃先温度が高まったときにも格段に優れた耐摩耗性と耐欠損性とを有する微粒超硬合金材が実現できる。 Highly tough, and by containing at least one element A that forms Cr and Cr and Laves phase ACr 2 in a binder phase mainly composed of Co, Cr and element A having greatly different atomic radii can be stabilized at the same time. It is contained in the binder phase, causing distortion in the binder phase due to the size effect, and the hardness and heat resistance of the binder phase itself can be greatly improved, and fine particles having excellent hardness and toughness even at high temperatures. A cemented carbide material can be realized. As a result, it can be applied to, for example, a small-diameter drill and the like, and a fine-grained cemented carbide material having excellent wear resistance and fracture resistance even when the cutting edge temperature is increased can be realized.
本発明の結合相中の元素Ａ含有量の総和が、結合相中のＣｒ含有量に対して３〜２５原子％とすることによって、原子半径が大きく結合相中に歪みを与え硬度と耐熱性を高める元素Ａと、原子半径が小さいＣｏとＣｒとが適度に結合相中に含有されることになり、硬度と靭性の両者が格段に優れた微粒超硬合金材が実現できる。炭化タングステン基超硬合金のＣｏ含有量を全組成の２〜１３質量％に配合するとともに、ラーベス相ＡＣｒ２を作るＣｒと元素Ａとを所定量添加して微粒超硬合金材用の成形体を作成し、焼結条件を工夫して処理する。例えば、シンターＨＩＰ処理条件を、１．３〜１３．２Ｐａの真空雰囲気中に１３３０〜１４８０℃の範囲内の所定温度に０．５〜２時間保持し、雰囲気の圧力を４．９〜１４．７ＭＰａの加圧雰囲気に変え、この加圧雰囲気中に１５〜６０分間保持する。更に、冷却工程では１０００℃までを５０〜１００度／分の冷却速度で急冷する。この様な処理方法を採用することにより、ＣｒとＣｒの原子半径より比較的大きい元素Ａとを組み合わせても、結合相中に固溶させることが容易となり、原子半径が大きく異なる元素ＡとＣｒの両者を、焼結後においても安定して結合相中に含有させることが出来る。結合相中に含有しているＣｏやＣｒ及び元素Ａ等の含有量は、例えば、超硬合金材を微細に粉砕した後、これを５％クエン酸アンモニウムと０．５％塩化ナトリウムの混合液からなる電解液で電解し、この電解液を誘導結合高周波プラズマ分光分析（以下、ＩＣＰ分析と記す。）することにより求められる。Ｃｒとラーベス相ＡＣｒ２を作る元素元素Ａとしては、例えばＴａ、Ｎｂ、Ｈｆ、Ｚｒ、Ｔｉ等がある。 When the sum of the element A contents in the binder phase of the present invention is 3 to 25 atomic% with respect to the Cr content in the binder phase, the atomic radius is large and the binder phase is distorted to give hardness and heat resistance. Element A that enhances the hardness, Co, and Cr having a small atomic radius are appropriately contained in the binder phase, and a fine cemented carbide material having both excellent hardness and toughness can be realized. A compact for fine-grained cemented carbide material by adding a predetermined amount of Cr and element A to make Laves phase ACr 2 while blending the Co content of tungsten carbide-based cemented carbide with 2 to 13% by mass of the total composition And process the sintering conditions. For example, the sintering HIP processing conditions are maintained in a vacuum atmosphere of 1.3 to 13.2 Pa at a predetermined temperature within a range of 1330 to 1480 ° C. for 0.5 to 2 hours, and the pressure of the atmosphere is 4.9 to 14. Change to a pressurized atmosphere of 7 MPa and hold in this pressurized atmosphere for 15-60 minutes. Further, in the cooling step, the material is rapidly cooled to 1000 ° C. at a cooling rate of 50 to 100 degrees / minute. By adopting such a processing method, even if Cr and an element A that is relatively larger than the atomic radius of Cr are combined, it becomes easy to form a solid solution in the binder phase, and the elements A and Cr having greatly different atomic radii. Both can be stably contained in the binder phase even after sintering. The content of Co, Cr and element A contained in the binder phase is, for example, a mixture of 5% ammonium citrate and 0.5% sodium chloride after finely grinding a cemented carbide material. The electrolytic solution is obtained by conducting inductively coupled high frequency plasma spectroscopic analysis (hereinafter referred to as ICP analysis). Examples of the element A that forms Cr and Laves phase ACr 2 include Ta, Nb, Hf, Zr, and Ti.
Ｃｏ含有量が全組成の２質量％未満だと、焼結体に十分な靭性が得られない。一方、１３質量％を超えると耐摩耗性が著しく低下する欠点が現れる。そこで、Ｃｏ含有量を全組成の２〜１３質量％とする。主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１．５質量％未満だと、ＷＣ硬質分散相の成長が進むことによりＷＣの平均粒径が０．９μｍを超え、耐摩耗性と靭性が低下する欠点が現れる。一方、１２質量％を超えると結合相中にＣｒが偏析し、結合相の靭性が著しく低下する。そこで、結合相中のＣｏに対するＣｒ含有量を１．５〜１２質量％とする。結合相中の元素Ａ含有量の総和が、結合相中のＣｒ含有量に対して３原子％未満では、結合相中に発生する歪み量が小さくなり、元素Ａを含有させる効果が小さくなる。一方、２５原子％を超えると結合相の靭性が低下する欠点が現れる。そこで、結合相中の元素Ａ含有量の総和は、結合相中のＣｒ含有量に対して３〜２５原子％とする。本発明の微粒超硬合金は、炭化タングステン基超硬合金の硬質分散相の平均粒径が０．９μｍ以下であり、平均粒径が０．９μｍを超えて大きい場合、例えば本発明の微粒超硬合金を用いて刃径が０．３ｍｍ以下の小径工具を作ると、粒径が大きいために刃先を加工したときの面粗さが悪くなるとともに、工具として使用時にチッピングが発生し易くなる欠点が現れる。そこで、炭化タングステン基超硬合金の硬質分散相の平均粒径を０．９μｍ以下とする。結合相中のＴａ及び／又はＮｂの総和は、結合相中のＣｒ含有量に対して３〜２５原子％である。これによりＷＣ硬質分散相の粒成長が抑えられ、平均粒径が０．９μｍ以下で高硬度の微粒超硬合金材が実現可能となる。２５原子％を超えて大きいと、Ｔａ及び／又はＮｂの偏析が発生し超硬合金の靭性が著しく低下し、細径化時に十分な耐欠損性が得られない。一方、３原子％未満だと結合相中にＣｒとともにＴａやＮｂを含有させる効果が著しく小さくなり、耐熱性と耐摩耗性が低下し、例えば高速切削時にドリル径が著しく摩耗する等の欠点が現れる。そこで、結合相中のＴａ及び／又はＮｂの総和は、結合相中のＣｒ含有量に対して３〜２５原子％とする。更に、結合相中のＴａ及び／又はＮｂの総和は、結合相中のＣｒ含有量に対して５〜２０原子％であることが、より好ましい。５〜２０原子％であることにより、更に優れた硬度と耐熱性が得られ、優れた耐摩耗性と耐欠損性とを有する微粒超硬合金材が実現できる。 If the Co content is less than 2% by mass of the total composition, sufficient toughness cannot be obtained in the sintered body. On the other hand, when it exceeds 13% by mass, there is a drawback that the wear resistance is remarkably lowered. Therefore, the Co content is 2 to 13% by mass of the total composition. If the Cr content with respect to Co is less than 1.5% by mass in the binder phase mainly composed of Co, the growth of the WC hard dispersion phase causes the average particle diameter of WC to exceed 0.9 μm, resulting in wear resistance. The drawback of reduced toughness appears. On the other hand, if it exceeds 12% by mass, Cr is segregated in the binder phase, and the toughness of the binder phase is significantly reduced. Then, Cr content with respect to Co in a binder phase shall be 1.5-12 mass%. When the total content of the element A in the binder phase is less than 3 atomic% with respect to the Cr content in the binder phase, the amount of strain generated in the binder phase becomes small and the effect of containing the element A becomes small. On the other hand, when it exceeds 25 atomic%, the defect that the toughness of the binder phase decreases appears. Therefore, the sum of the element A contents in the binder phase is 3 to 25 atomic% with respect to the Cr content in the binder phase. The fine cemented carbide of the present invention has an average particle size of the hard dispersed phase of the tungsten carbide-based cemented carbide of 0.9 μm or less, and the average particle size is larger than 0.9 μm. When a small diameter tool with a blade diameter of 0.3 mm or less is made using a hard alloy, the surface roughness when processing the cutting edge is deteriorated due to the large particle size, and chipping is likely to occur when used as a tool. Appears. Therefore, the average particle diameter of the hard dispersed phase of the tungsten carbide base cemented carbide is set to 0.9 μm or less. The sum total of Ta and / or Nb in the binder phase is 3 to 25 atomic% with respect to the Cr content in the binder phase. Thereby, grain growth of the WC hard dispersed phase is suppressed, and a high-hardness fine cemented carbide alloy material having an average particle diameter of 0.9 μm or less can be realized. If it exceeds 25 atomic%, segregation of Ta and / or Nb occurs, and the toughness of the cemented carbide is remarkably lowered, and sufficient fracture resistance cannot be obtained when the diameter is reduced. On the other hand, if it is less than 3 atomic%, the effect of including Ta and Nb together with Cr in the binder phase is remarkably reduced, and the heat resistance and wear resistance are lowered. For example, the drill diameter is significantly worn during high speed cutting. appear. Therefore, the total sum of Ta and / or Nb in the binder phase is 3 to 25 atomic% with respect to the Cr content in the binder phase. Furthermore, the total sum of Ta and / or Nb in the binder phase is more preferably 5 to 20 atomic% with respect to the Cr content in the binder phase. By being 5 to 20 atomic%, further excellent hardness and heat resistance can be obtained, and a fine cemented carbide material having excellent wear resistance and fracture resistance can be realized.
本発明の微粒超硬合金は結合相中に、Ｃｒに対して原子半径の比較的大きいＭｏを含有する。結合相中のＣｒに対するＭｏ含有量が１〜１０原子％の場合、耐熱性と硬度とのバランスが良くなることにより、両特性が高まる。従って高速切削において優れた耐摩耗性と耐欠損性とを有する微粒超硬合金材が実現できる。そこで、結合相中のＣｒに対するＭｏ含有量は１〜１０原子％である。本発明の微粒超硬合金は、結合相中に原子半径の比較的大きいＹ及び／又はＬａ、Ｃｅ、Ｙｂ等の希土類元素の含有量を、Ｃｒに対して０．０５〜０．２原子％含有していると、硬質相と結合相間の濡れ性が改善され、高速切削において更に優れた耐摩耗性と耐欠損性とを有する微粒超硬合金材が実現できる。そこで、結合相中のＣｒに対するＹ及び／又は希土類元素の含有量は、０．０５〜０．２原子％とした。本発明の微粒超硬合金材は、結合相中に微量のＷ、Ｎｉ、Ｖ、Ｔｉ、Ｈｆ、Ｚｒを加えても良い。数質量％のＷを結合相中に含有させることにより、更に硬度と靭性とが高まる利点が得られる。Ｖ、Ｔｉ、Ｈｆ、Ｚｒを微少量添加すると硬質相の平均粒径が小さくなり硬度が高まる利点が得られるが、含有量が多いと靭性が低下する欠点が現れる。Ｎｉを含有させると耐熱性が高まる利点が得られるが、靭性が低下する欠点が現れる。本発明は、特に刃径が０．３ｍｍ以下等の小径工具、特に小径ドリルやルーター等に有用であるが、切削工具でなくとも径の小さい耐摩耗工具、押しピン、金型等にも有効である。 The fine cemented carbide of the present invention contains Mo having a relatively large atomic radius with respect to Cr in the binder phase. When the Mo content with respect to Cr in the binder phase is 1 to 10 atomic%, both properties are enhanced by improving the balance between heat resistance and hardness. Therefore, a fine cemented carbide material having excellent wear resistance and fracture resistance in high-speed cutting can be realized. Therefore, the Mo content with respect to Cr in the binder phase is 1 to 10 atomic%. The fine cemented carbide of the present invention has a relatively large atomic radius of Y and / or rare earth elements such as La, Ce, and Yb in the binder phase, 0.05 to 0.2 atomic% with respect to Cr. If it is contained, the wettability between the hard phase and the binder phase is improved, and a fine cemented carbide material having further excellent wear resistance and fracture resistance in high-speed cutting can be realized. Therefore, the content of Y and / or rare earth elements with respect to Cr in the binder phase is set to 0.05 to 0.2 atomic%. The fine grain cemented carbide material of the present invention may contain a small amount of W, Ni, V, Ti, Hf, Zr in the binder phase. By containing several mass% W in the binder phase, the advantage of further increasing hardness and toughness can be obtained. When a small amount of V, Ti, Hf, or Zr is added, there is an advantage that the average particle size of the hard phase is reduced and the hardness is increased. However, when the content is large, a disadvantage that the toughness is lowered appears. When Ni is contained, there is an advantage that the heat resistance is increased, but a disadvantage that the toughness is lowered appears. The present invention is particularly useful for small-diameter tools having a blade diameter of 0.3 mm or less, especially small-diameter drills and routers. It is.
原料粉末として、平均粒径が０．６μｍのＷＣ粉末、平均粒径が１．５μｍのＣｒ３Ｃ２粉末、同１．２μｍの（Ｔａ、Ｗ）Ｃ粉末、同１．２μｍのＮｂＣ粉末、同１．５μｍのＭｏ２Ｃ粉末、同１．５μｍのＹｂ２Ｏ３粉末、同１．５μｍのＹ２Ｏ３粉末、同１．５μｍのＬａ２Ｏ３粉末、同１．５μｍのＧｄ２Ｏ３粉末及び同１．５μｍのＣｏ粉末を用意し、これらの原料粉末を所定の組成に配合し、アトライターで１２時間混合し、減圧乾燥し、更にワックスと溶剤を加えて１時間混合した。押出し成形機により直径２．５ｍｍの長尺状成形体を作製し、これらの長尺状成形体を脱ワックスした後、１．３〜１３．２Ｐａの真空雰囲気中に１３３０〜１４８０度の範囲内の所定温度に０．５〜２時間保持し、雰囲気の圧力を４．９〜１４．７ＭＰａの加圧雰囲気に変え、この加圧雰囲気中に１５〜６０分間保持する。更に、冷却工程では１０００℃までを５０〜１００度／分の冷却速度で急冷することにより、微粒超硬合金からなる直径２ｍｍの長尺状焼結素材を製造した。この長尺状焼結素材の組成は蛍光Ｘ線装置により定量分析し、全組成に対するＣｏ量を求めた。平均結晶粒径は、焼結素材の断面を鏡面研磨した後、村上試薬で０．５分、王水で０．５分間エッチングすることにより結晶粒界を明確にした。走査型電子顕微鏡（以下、ＳＥＭと記す。）により倍率１０ｋ倍で撮影した画像を拡大コピーし、これを画像解析装置により解析することにより算出した。結合相中に含有しているＣｏ、Ｔａ、Ｎｂ、Ｍｏ、Ｙｂ、Ｙ、Ｌａ、Ｇｄ等の含有量は、各超硬合金材を微細に粉砕し、５％クエン酸アンモニウムと０．５％塩化ナトリウムの混合液からなる電解液で電解した後、この電解液をＩＣＰ分析することにより求めた。これらの評価結果を表１にまとめて示した。 As raw material powders, WC powder having an average particle diameter of 0.6 μm, Cr 3 C 2 powder having an average particle diameter of 1.5 μm, (Ta, W) C powder having the same particle diameter of 1.2 μm, NbC powder having the same particle diameter of 1.2 μm, Same 1.5 μm Mo 2 C powder, same 1.5 μm Yb 2 O 3 powder, same 1.5 μm Y 2 O 3 powder, same 1.5 μm La 2 O 3 powder, same 1.5 μm Gd 2 O 3 powder and Co powder of 1.5 μm were prepared, these raw material powders were blended to a predetermined composition, mixed for 12 hours with an attritor, dried under reduced pressure, and further mixed with wax and solvent for 1 hour. . Within a range of 1330 to 1480 degrees in a vacuum atmosphere of 1.3 to 13.2 Pa after producing long shaped bodies with a diameter of 2.5 mm by an extrusion molding machine and dewaxing these long shaped bodies. At a predetermined temperature of 0.5 to 2 hours, the pressure of the atmosphere is changed to a pressurized atmosphere of 4.9 to 14.7 MPa, and the pressurized atmosphere is held for 15 to 60 minutes. Furthermore, in the cooling step, a long sintered material having a diameter of 2 mm made of a fine cemented carbide was manufactured by rapidly cooling to 1000 ° C. at a cooling rate of 50 to 100 degrees / minute. The composition of the long sintered material was quantitatively analyzed with a fluorescent X-ray apparatus to determine the Co amount relative to the total composition. The average grain size was clarified by mirror-polishing the cross section of the sintered material and then etching 0.5 minutes with Murakami reagent and 0.5 minutes with aqua regia. The image was calculated by enlarging and copying an image taken at a magnification of 10 k with a scanning electron microscope (hereinafter referred to as SEM) and analyzing the image with an image analyzer. The contents of Co, Ta, Nb, Mo, Yb, Y, La, Gd, etc. contained in the binder phase are determined by finely grinding each cemented carbide material, 5% ammonium citrate and 0.5%. After electrolysis with an electrolytic solution comprising a mixed solution of sodium chloride, the electrolytic solution was determined by ICP analysis. The evaluation results are summarized in Table 1.
比較例として、本発明例と同じ原料粉の組み合わせを用いているものの、組成が本発明例と異なる成形体を作成した。焼結条件は６．６Ｐａの真空雰囲気中に１３５０〜１４８０℃の範囲内の所定の温度に１．５時間保持した。しかし、冷却工程の冷却速度条件は本発明例と異なる約１０度／分の炉冷とした。本発明例及び比較例から作製した長尺状焼結素材を用いて、シャンク径２．０ｍｍ、刃先径０．１ｍｍの２枚刃小径ドリルを各３本作製した。これを用いて、高ガラス転移温度の０．２ｍｍ厚さ両面Ｃｕ付きガラスエポキシ板を２枚重ねにしたものを、回転数を２０００００回転／分、送り０．０１ｍｍ／ｒｅｖの条件で穴開け加工試験を行なった。この条件は、より高速で切削するため、刃先温度がより高温になりやすい切削条件である。外周刃外径寸法に５％の摩耗が生じる迄の穴開け加工数又は折損するまでの加工穴数の小さい方を測定し、各３本の平均を穴あけ平均寿命とした。本発明例及び比較例から作製した各小径ドリルの穴開け平均寿命測定結果を表１に併せて示した。 As a comparative example, the same raw material powder combination as in the present invention example was used, but a molded product having a composition different from that of the present invention example was prepared. Sintering conditions were maintained in a vacuum atmosphere of 6.6 Pa at a predetermined temperature in the range of 1350 to 1480 ° C. for 1.5 hours. However, the cooling rate condition in the cooling step was furnace cooling of about 10 degrees / minute, which is different from the example of the present invention. Three long blades each having a shank diameter of 2.0 mm and a cutting edge diameter of 0.1 mm were produced using the long sintered material produced from the inventive examples and comparative examples. Using this, two glass epoxy plates with a high glass transition temperature of 0.2 mm thick double-sided Cu are stacked on top of each other under the conditions of a rotational speed of 200000 rpm and a feed of 0.01 mm / rev. A test was conducted. This condition is a cutting condition in which the cutting edge temperature tends to be higher because cutting is performed at a higher speed. The smaller of the number of holes drilled until 5% wear occurred on the outer diameter of the outer peripheral blade or the number of holes drilled until breakage was measured, and the average of the three holes was defined as the average drilling life. Table 1 also shows the results of measuring the average drilling life of each small-diameter drill produced from the inventive examples and the comparative examples.
表１より、本発明例１〜３６はいずれも、炭化タングステン基超硬合金の硬質分散相の平均粒径が０．９μｍ以下で、Ｃｏ量含有量が２〜１３質量％、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１．５〜１２質量％、Ｃｒとラーベス相ＡＣｒ２を作る元素ＡとしてＴａ及び／又はＮｂが含有されており、Ｔａ及び／又はＮｂの結合相中含有量の総和が、結合相中のＣｒ含有量に対して３〜２５原子％となっている。従って、本発明例１〜３６と比較例３７〜４３とを比較すると、本発明例を用いて作製した小径ドリルは比較例に比べて１．６倍以上穴あけ寿命が長く優れている。本発明例１５と比較例３７とを比較すると、Ｃｏ量含有量、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が同じであっても、結合相中にラーベス相ＡＣｒ２を作る元素ＡとしてＴａが添加されている本発明例１５は、元素Ａを含有していない比較例３７に比べて穴あけ寿命が４．２倍寿命が長く、格段に工具特性が優れている。この理由は、結合相中にラーベス相が存在することにより、結合相自体の硬度と耐熱性とが大幅に改善し、高温での優れた硬度と靭性とを有するためである。比較例３７は、結合相中にＣｒが含有されているものの、ラーベス相ＡＣｒ２を作る元素Ａを含有しておらず、単に、原子半径の小さいＶが含有されているだけである。Ｃｏ含有量が異なる本発明例１〜８と比較例３８、３９とを比較すると、本発明例１〜８は比較例３８、３９に比べて穴あけ寿命が２．２倍以上優れている。この理由は、Ｃｏ量が本発明の規定値範囲内であることにより、靭性と耐摩耗性とのバランスが保たれているためである。主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が本発明の規定値範囲内である本発明例９〜１１と、規定値外の比較例４０、４１とを比較すると本発明例の寿命の方が１．６倍以上優れている。この理由は、結合相中にＣｏに対するＣｒ含有量が本発明の規定値範囲内であることにより、ＷＣ硬質分散相の成長を抑制する効果が得られ、またＣｒが結合相中に偏析していないために、靭性と耐摩耗性とが確保されているためである。比較例４０はＣｒ含有量が少なく、ＷＣ硬質分散相の成長を抑制する効果が不十分であり、一方、比較例４１がＣｒ含有量が多いために結合相中に偏析し、靭性が低下したためである。元素Ａの含有量が本発明の規定値範囲内である本発明例１２〜２３と、規定値外の比較例４２、４３とを比較すると本発明例の寿命の方が１．７倍以上優れている。この理由は、元素ＡであるＴａ及び／又はＮｂの含有量が本発明の規定値範囲内であることにより、添加効果が得られているためである。比較例４２は添加量が少ないために、結合相中に発生する歪み量が小さく、耐摩耗性と耐欠損性の改善効果が見られなかったためである。一方、比較例４３は添加量が多いために、結合相の靭性が低下したためである。 From Table 1, Examples 1-3 of the invention all have an average particle size of the hard dispersed phase of the tungsten carbide-based cemented carbide of 0.9 μm or less, a Co content of 2-13 mass%, mainly from Co. In the binder phase, the Cr content with respect to Co is 1.5 to 12% by mass, and Ta and / or Nb is contained as the element A for forming the Laves phase ACr 2 with Cr. In the binder phase of Ta and / or Nb The total content is 3 to 25 atomic% with respect to the Cr content in the binder phase. Therefore, when Examples 1-36 of the present invention and Comparative Examples 37-43 are compared, the small-diameter drill produced using the examples of the present invention has an excellent drilling life of 1.6 times or more as compared with the comparative example. When Example 15 of the present invention and Comparative Example 37 are compared, even if the Co content is the same, and the Cr content relative to Co is the same in the binder phase mainly composed of Co, the element that forms the Laves phase ACr 2 in the binder phase Invention Example 15 in which Ta is added as A has a drilling life 4.2 times longer than that of Comparative Example 37 containing no element A, and has excellent tool characteristics. This is because the presence of the Laves phase in the binder phase greatly improves the hardness and heat resistance of the binder phase itself, and has excellent hardness and toughness at high temperatures. Although the comparative example 37 contains Cr in the binder phase, it does not contain the element A that forms the Laves phase ACr 2 , and merely contains V having a small atomic radius. Inventive Examples 1 to 8 and Comparative Examples 38 and 39 having different Co contents are compared with Comparative Examples 38 and 39, and Inventive Examples 1 to 8 are superior to Comparative Examples 38 and 39 by 2.2 times or more. This is because the balance between toughness and wear resistance is maintained when the amount of Co is within the specified range of the present invention. When the present invention examples 9 to 11 in which the content of Cr with respect to Co in the binder phase mainly composed of Co is within the specified value range of the present invention are compared with comparative examples 40 and 41 outside the specified value, the lifetime of the present invention example Is more than 1.6 times better. This is because the Cr content relative to Co in the binder phase is within the specified range of the present invention, so that the effect of suppressing the growth of the WC hard dispersed phase is obtained, and Cr is segregated in the binder phase. This is because toughness and wear resistance are ensured. In Comparative Example 40, the Cr content is low and the effect of suppressing the growth of the WC hard dispersion phase is insufficient. On the other hand, Comparative Example 41 is segregated in the binder phase because of the high Cr content, and the toughness is reduced. It is. When the present invention examples 12 to 23 in which the content of the element A is within the specified value range of the present invention and the comparative examples 42 and 43 outside the specified value are compared, the lifetime of the present invention example is 1.7 times or more superior. ing. This is because the addition effect is obtained when the content of the element A, Ta and / or Nb, is within the specified range of the present invention. This is because in Comparative Example 42, since the addition amount was small, the amount of strain generated in the binder phase was small, and the effect of improving wear resistance and fracture resistance was not observed. On the other hand, in Comparative Example 43, since the addition amount was large, the toughness of the binder phase was lowered.
本発明例内の本発明例１２〜１９を比較する。Ｃｏ含有量が７．９質量％、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１０質量％と同じであるが、結合相中に含有されているＴａ量が、結合相中のＣｒ含有量に対して５〜２０原子である本発明例１４〜１７は、Ｔａ量が、結合相中のＣｒ含有量に対して３原子％、４原子％の本発明例１２、１３、及び２１原子％、２５原子％の本発明例１８、１９に比べて１．３倍以上穴あけ寿命が長い。本発明例２０と１３、本発明例２１と１５、本発明例２２と１６、本発明例２３と１７とを夫々比較する。Ｔａの一部又は全部をＮｂに置換してもほぼ同等の穴あけ寿命が得られる。しかも、結合相中のＴａ及び／又はＮｂの含有量総和が、結合相中のＣｒ含有量に対して５〜２０原子％である本発明例２１、２２は、Ｃｒ含有量が４原子％、２１原子％の本発明例２０と２３に比べて１．３倍以上穴あけ寿命が長い。この理由は、より優れた硬度と耐熱性が得られ、より優れた耐摩耗性と耐欠損性とを有するためである。従って、結合相中のＴａ及び／又はＮｂの含有量の総和が、結合相中のＣｒ含有量に対して５〜２０原子％含有されていることが好ましい。本発明例２４〜２６と本発明例１５、２７とを比較する。何れもＣｏ量が７．９質量％、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１０質量％、Ｔａ含有量が１０質量％と同じである。しかし、結合相中のＣｒに対するＭｏ含有量が１〜１０原子％の範囲で含有されている本発明例２４〜２６は、結合相中にＭｏを含有していない本発明例１５や、Ｍｏ含有量が１２原子％の本発明例２７に比べて、穴開け寿命が１．４倍以上長く優れている。この理由は、Ｍｏの添加によってより優れた耐摩耗性と耐欠損性とを有するためである。従って、結合相中のＣｒに対するＭｏ含有量が１〜１０原子％であることが好ましい。本発明例２８、２９と、本発明例１５、３０とを比較する。何れもＣｏ量が７．９質量％、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１０質量％、Ｔａ含有量が１０原子％と同じである。しかし、結合相中のＣｒに対するＹｂの含有量が０．０５〜０．２０原子％の範囲で含有されている本発明例２８、２９は、結合相中にＹｂを含有していない本発明例１５やＹｂ含有量が０．２５原子％の本発明例３０に比べて、穴開け寿命が１．３倍以上長く優れている。また、本発明例３１、３２と、本発明例２５、３３とを比較すると、何れもＣｏ量が７．９質量％、主にＣｏからなる結合相中にＣｏに対するＣｒ含有量が１０質量％、Ｔａ含有量が１０原子％、Ｍｏ含有量が５原子％と同じであるが、結合相中のＣｒに対するＹｂの含有量が０．０５〜０．２０原子％含有されている本発明例３１、３２は、結合相中にＹｂを含有していない本発明例２５やＹｂ含有量が０．２５原子％の本発明例３３に比べて、穴開け寿命が更に１．１倍長くなり優れている。更に、本発明例３４〜３６では、Ｙｂ以外にＹ、Ｌａ、Ｇｄ等の希土類元素をＣｏ中に含有させることにより、穴開け寿命が改善する結果を得た。この理由は、結合相中に希土類元素の含有量を、Ｃｒに対して０．０５〜０．２原子％含有することにより、硬質相と結合相間の濡れ性が改善され、より優れた耐摩耗性と耐欠損性が得られるためである。従って、結合相中のＣｒに対するＹ及び／又は希土類元素の含有量が０．０５〜０．２原子％含有されていることが好ましい。
Inventive Examples 12 to 19 within the inventive examples are compared. The Co content is 7.9% by mass, and the Cr content relative to Co in the binder phase mainly composed of Co is the same as 10% by mass. However, the amount of Ta contained in the binder phase is less than that in the binder phase. Inventive Examples 14 to 17 having 5 to 20 atoms with respect to the Cr content, Inventive Examples 12 and 13 in which the Ta content is 3 atomic% and 4 atomic% with respect to the Cr content in the binder phase, and The drilling life is 1.3 times longer than that of Invention Examples 18 and 19 of 21 atomic% and 25 atomic%. Invention Examples 20 and 13, Invention Examples 21 and 15, Invention Examples 22 and 16, and Invention Examples 23 and 17 are compared. Even if part or all of Ta is replaced with Nb, almost the same drilling life can be obtained. Moreover, the present invention examples 21 and 22 in which the total content of Ta and / or Nb in the binder phase is 5 to 20 atomic% with respect to the Cr content in the binder phase, the Cr content is 4 atomic%, The drilling life is 1.3 times longer than that of Invention Examples 20 and 23 of 21 atomic%. This is because more excellent hardness and heat resistance can be obtained, and more excellent wear resistance and fracture resistance. Accordingly, the total content of Ta and / or Nb in the binder phase is preferably 5 to 20 atomic% with respect to the Cr content in the binder phase. Invention Examples 24-26 and Invention Examples 15 and 27 are compared. In any case, the Co content is 7.9% by mass, the Cr content with respect to Co in the binder phase mainly composed of Co is 10% by mass, and the Ta content is 10% by mass. However, the present invention examples 24-26 in which the Mo content with respect to Cr in the binder phase is contained in the range of 1 to 10 atomic% are the invention examples 15 and Mo containing no Mo in the binder phase. Compared with the invention example 27 of which the amount is 12 atomic%, the drilling life is 1.4 times longer and superior. This is because the addition of Mo has better wear resistance and fracture resistance. Therefore, it is preferable that the Mo content with respect to Cr in the binder phase is 1 to 10 atomic%. Invention Examples 28 and 29 are compared with Invention Examples 15 and 30. In any case, the Co content is 7.9% by mass, the Cr content with respect to Co in the binder phase mainly composed of Co is 10% by mass, and the Ta content is the same as 10 atomic%. However, Examples 28 and 29 of the present invention in which the content of Yb with respect to Cr in the binder phase is contained in the range of 0.05 to 0.20 atomic% are examples of the invention in which Yb is not contained in the binder phase. 15 and Yb content is 0.25 atomic%, and the drilling life is 1.3 times longer than that of Invention Example 30. Further, when Invention Examples 31 and 32 are compared with Invention Examples 25 and 33, the Co content is 7.9% by mass, and the Cr content relative to Co in the binder phase mainly composed of Co is 10% by mass. Inventive Example 31 in which the Ta content is the same as 10 atomic% and the Mo content is 5 atomic%, but the Yb content relative to Cr in the binder phase is 0.05 to 0.20 atomic%. , 32 is excellent in that the drilling life is further 1.1 times longer than in the inventive example 25 which does not contain Yb in the binder phase and the inventive example 33 in which the Yb content is 0.25 atomic%. Yes. Further, in Examples 34 to 36 of the present invention, the result of improving the drilling life was obtained by including rare earth elements such as Y, La, and Gd in addition to Yb in Co. The reason for this is that the wet phase between the hard phase and the binder phase is improved by containing the rare earth element content in the binder phase in the range of 0.05 to 0.2 atomic% with respect to Cr, and the wear resistance is improved. This is because the properties and fracture resistance are obtained. Therefore, it is preferable that the content of Y and / or rare earth elements with respect to Cr in the binder phase is 0.05 to 0.2 atomic%.
Claims (4)
The fine grain cemented carbide according to any one of claims 1 to 3, wherein the content of Y and / or rare earth elements with respect to Cr in the binder phase is 0.05 to 0.2 atomic%. Cemented carbide.
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| JP2012162753A (en) * | 2011-02-03 | 2012-08-30 | Sumitomo Electric Hardmetal Corp | Cemented carbide and method of manufacturing the same, and micro drill |
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| JP2012162753A (en) * | 2011-02-03 | 2012-08-30 | Sumitomo Electric Hardmetal Corp | Cemented carbide and method of manufacturing the same, and micro drill |
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