JP6106323B1 - Sintered tungsten-based alloy and method for producing the same - Google Patents
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Abstract
【課題】延性が高く且つ高精度な焼結タングステン基合金及びその製造方法を提供する。【解決手段】Ｗを９０．０質量％以上含有し、残部がＣｕ、Ｆｅ及びＭｏの中から選ばれる１種以上、Ｎｉ及び不可避不純物からなり、炭素含有量が１２質量ppm以下、引張伸びが９％以上であり、好ましくは、断面組織での空孔の面積率が１％未満である。この焼結体は、粒径の粗いＷ粉末を用い、このＷ粉末とＮｉ粉末などの副原料からなる原料粉末に、有機バインダーを添加せず、少量の固形潤滑剤のみを添加した上で、造粒することなく機械的に混合し、この混合粉体を比較的高い成形圧で所定の成形密度の成形体に成形し、この成形体を脱脂した後、焼結することにより得られる。【選択図】図１A highly ductile and highly accurate sintered tungsten-based alloy and a method for producing the same are provided. SOLUTION: W is contained in 90.0% by mass or more, the balance is one or more selected from Cu, Fe and Mo, Ni and inevitable impurities, the carbon content is 12 mass ppm or less, and the tensile elongation is It is 9% or more, and preferably the area ratio of vacancies in the cross-sectional structure is less than 1%. This sintered body uses W powder having a coarse particle diameter, and after adding only a small amount of solid lubricant to the raw material powder made of auxiliary materials such as W powder and Ni powder, without adding an organic binder, It is obtained by mechanically mixing without granulation, forming the mixed powder into a molded body having a predetermined molding density with a relatively high molding pressure, degreasing the molded body, and then sintering. [Selection] Figure 1
Description
本発明は、延性が高く且つ高精度な焼結タングステン基合金（粉末焼結体）とその製造方法に関するものである。 The present invention relates to a sintered tungsten-based alloy (powder sintered body) having high ductility and high accuracy, and a method for producing the same.
焼結タングステン基合金の部品は、硬さがＨｖ２５０以上あることから切削が容易ではなく、このため粉末焼結体をできるだけ高精度に製造することが求められる。焼結タングステン基合金の一般的な製造法では、粒径２〜４μｍ程度のＷ粉末と副原料（Ｎｉ粉末などの結合相形成成分）からなる原料粉末に有機バインダーを添加して混練した後、ＭＩＭで成型するか、流動性や成形性を確保するためスプレードライヤーなどで造粒した上でプレス成形する。このプレス成形では、成形密度が高すぎると脱脂しにくくなるので、成形圧を２ｔ／ｃｍ２以下とし、成形密度を１０ｇ／ｃｍ３以下とするのが通常である。 A sintered tungsten-based alloy part has a hardness of Hv250 or more, and therefore is not easily cut. Therefore, it is required to produce a powder sintered body with as high accuracy as possible. In a general manufacturing method of a sintered tungsten-based alloy, after adding and kneading an organic binder to a raw material powder composed of W powder having a particle size of about 2 to 4 μm and an auxiliary raw material (a binder phase forming component such as Ni powder), Molded with MIM, or granulated with a spray dryer to ensure fluidity and moldability and then press molded. In this press molding, if the molding density is too high, it is difficult to degrease, so that the molding pressure is usually 2 t / cm 2 or less and the molding density is 10 g / cm 3 or less.
特許文献１には、Ｗを９８質量％以上含有し、密度が１８．６ｇ／ｃｍ３以上の高密度材料（焼結タングステン基合金）の製造方法として、平均粒径４μｍのＷ粉末が９８質量％、残部が平均粒径２〜５μｍのＮｉ粉末、Ｆｅ粉末及びＣｕ粉末からなる原料粉末に有機バインダーを添加して混合した後、スプレードライヤーで造粒し、その造粒粉を１ｔ／ｃｍ２の圧力でプレス成形し、この成形体を脱脂処理した上で焼結することが示されている。 In Patent Document 1, as a method for producing a high-density material (sintered tungsten-based alloy) containing 98 mass% or more of W and having a density of 18.6 g / cm 3 or more, 98 mass of W powder having an average particle diameter of 4 μm is used. %, The balance is Ni powder having an average particle diameter of 2 to 5 μm, Fe powder and Cu powder, and an organic binder is added and mixed, then granulated with a spray dryer, and the granulated powder is 1 t / cm 2. It is shown that the molded body is press-molded at a pressure of, and the molded body is degreased and then sintered.
焼結タングステン基合金は、Ｗ含有量が多いほど焼結時の液相が少ないため、延性がでにくいという問題がある。このため従来の製造法では、焼結後に延性を改善するための熱処理を施す場合もある。
また、従来、焼結タングステン基合金を製造するには、焼結組織の均一性を確保するために、粒径が細かいＷ粉末（２〜４μｍ程度）を用いる必要があると考えられている。しかし、このような粒径が細かいＷ粉末は、成形する際の流動性が悪く、しかも圧縮性が低くなることにより成形性も悪くなるため、そのままでは原料粉末として用いることができない。そこで、特許文献１に示されるように、Ｗ粉末を主体とする原料粉末に有機バインダーを添加して混合・造粒し、原料粉末の流動性と成形性を確保した上で成形を行っており、このバインダー成分は成形後の脱脂処理により分解除去するようにしている。ここで、原料粉末の成形圧（成形密度）を高くすると、脱脂処理中にバインダー成分が分解したガスの放散が生じにくくなるため、バインダー成分の除去が不十分となり、未分解のバインダー成分が残留してしまう。このため、従来の製造方法では、成形圧（成形密度）を高くできず、その結果、焼結時の収縮量が大きくなり、高精密な焼結体が得られないという問題があった。
A sintered tungsten-based alloy has a problem that ductility is less likely because the liquid content during sintering is smaller as the W content is higher. For this reason, in the conventional manufacturing method, the heat processing for improving ductility may be performed after sintering.
Conventionally, in order to produce a sintered tungsten-based alloy, it is considered that it is necessary to use W powder (about 2 to 4 μm) having a small particle size in order to ensure the uniformity of the sintered structure. However, such a W powder having a small particle size has poor fluidity during molding, and also has poor moldability due to low compressibility, and thus cannot be used as a raw material powder as it is. Therefore, as shown in Patent Document 1, an organic binder is added to a raw material powder mainly composed of W powder, mixed and granulated, and molding is performed after ensuring the fluidity and formability of the raw material powder. The binder component is decomposed and removed by degreasing after molding. Here, if the molding pressure (molding density) of the raw material powder is increased, it becomes difficult for gas decomposed during the degreasing process to be emitted, so that removal of the binder component becomes insufficient and undecomposed binder component remains. Resulting in. For this reason, the conventional manufacturing method cannot increase the molding pressure (molding density). As a result, there is a problem that the amount of shrinkage during sintering becomes large and a highly precise sintered body cannot be obtained.
また、焼結タングステン基合金が適用されるような部品のなかには、一部又は全体の厚さ（肉厚）が０．５ｍｍ未満であるような薄物もあるが、従来の粉末成形焼結法では、原料粉末に有機バインダーを添加して混合・造粒するため、平均粒径が数十から１００μｍ近くまで大きくなり、このため０．５ｍｍ未満の厚さを有するような薄物の成形は困難である。また、上述したように成形密度が小さいため、ハンドリング可能な薄物の成形体を作ること自体も難しい。また、ＭＩＭの場合は、薄物の成形は可能であるが、収縮率が大きく、平面度などの精度もでにくいため、実際上の適用は難しい。したがって、従来の製造方法では、高精度な薄物の焼結体を得ることは難しかった。 In addition, some of the parts to which sintered tungsten-based alloys are applied include thin parts having a partial or total thickness (wall thickness) of less than 0.5 mm. In addition, since an organic binder is added to the raw material powder and mixed and granulated, the average particle size increases from several tens to nearly 100 μm, and thus it is difficult to form a thin material having a thickness of less than 0.5 mm. . Moreover, since the molding density is small as described above, it is difficult to produce a thin molded body that can be handled. In addition, in the case of MIM, it is possible to mold a thin object, but practical application is difficult because the shrinkage rate is large and accuracy such as flatness is difficult. Therefore, it has been difficult to obtain a highly accurate thin sintered body by the conventional manufacturing method.
したがって本発明の目的は、以上のような従来技術の課題を解決し、延性が高く且つ高精度であって、薄肉化も可能な焼結タングステン基合金とその製造方法を提供することにある。 Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide a sintered tungsten-based alloy that has high ductility, high accuracy, and can be thinned, and a method for manufacturing the same.
本発明者らは、焼結タングステン基合金について、上記課題を解決するために検討を重ねた結果、以下のような知見を得た。
（i） 焼結タングステン基合金は、ヘビーアロイメカニズム（The Heavy Alloy Mechanism）と呼ばれる液相焼結により緻密化される。この液相焼結中は、Ｗ粉末がＷとＮｉ，Ｆｅなどの添加成分で構成される液相の中に固溶し、再析出を繰り返すことによりＷ粒成長をして緻密化する。Ｗ粒は高純度のＷとなり、炭素などの不純物は液相中に残るが、焼結後、その不純物はＷ粒の周辺に偏析する傾向にあり、これらの不純物のなかの炭素の残留量が延性に大きな影響を与えること、すなわち炭素の残留量が多いとＷ粒子間或いはＷ粒子と旧液相部である合金部との界面の接着が不十分となり、焼結体の延性が低下することが判った。さらに、炭素の残留量が多いと液相焼結時の濡れ性が悪くなって空孔を生じやすくなり、高密度化が阻害されることが判った。したがって、延性が高い焼結タングステン基合金を得るには、焼結後の炭素の残留量を十分に低減させる必要があることが判った。また、高Ｗ含有量の高密度焼結タングステン基合金は、焼結時の液相が少ないために特に延性がでにくいため、炭素の残留量を低減させて延性改善を図ることが特に有効であることが判った。
As a result of repeated studies on the sintered tungsten-based alloy to solve the above problems, the present inventors have obtained the following knowledge.
(I) The sintered tungsten-based alloy is densified by liquid phase sintering called the heavy alloy mechanism. During this liquid phase sintering, the W powder is solid-dissolved in the liquid phase composed of W and additive components such as Ni, Fe, etc., and by reprecipitation, W grains grow and become dense. The W grains become highly pure W, and impurities such as carbon remain in the liquid phase, but after sintering, the impurities tend to segregate around the W grains, and the residual amount of carbon in these impurities is Having a large effect on ductility, that is, if there is a large amount of residual carbon, the adhesion between the W particles or the interface between the W particles and the alloy part which is the old liquid phase part becomes insufficient, and the ductility of the sintered body decreases. I understood. Furthermore, it has been found that if the amount of carbon remaining is large, the wettability during liquid phase sintering deteriorates and pores are easily formed, and the densification is hindered. Therefore, it has been found that in order to obtain a sintered tungsten-based alloy having high ductility, it is necessary to sufficiently reduce the residual amount of carbon after sintering. Also, high-density sintered tungsten-based alloys with high W content are particularly difficult to ductile because of the low liquid phase during sintering, so it is particularly effective to reduce the residual amount of carbon and improve ductility. It turns out that there is.
（ii） 焼結体に残留している炭素の多くは、脱脂処理で分解除去できずに残留したバインダー成分に由来していることが判った。従来法では原料粉末の成形圧（成形密度）を低めに抑え、脱脂処理でバインダー成分が適切に分解除去されるようにしているが、上述したように焼結時の収縮量が大きくなり、高精密な焼結体が得られない。さらに、原料粉末の成形圧（成形密度）を低めに抑えたとしても、脱脂処理で分解しきれないバインダー成分（炭素）が残留し、焼結体の延性を低下させ、さらには高密度化も阻害していることが判った。 (Ii) It has been found that most of the carbon remaining in the sintered body is derived from the binder component remaining without being decomposed and removed by the degreasing treatment. In the conventional method, the molding pressure (molding density) of the raw material powder is kept low, and the binder component is appropriately decomposed and removed by the degreasing treatment. A precise sintered body cannot be obtained. Furthermore, even if the molding pressure (molding density) of the raw material powder is kept low, binder components (carbon) that cannot be decomposed by the degreasing process remain, reducing the ductility of the sintered body and further increasing the density. It turns out that it is inhibiting.
（iii） そこで、有機バインダーを用いない粉末成形焼結法について検討した結果、従来技術では細かい粒径（２〜４μｍ程度）のＷ粉末を用いるのが半ば常識化しているのに対して、敢えて粗い粒径（７μｍ以上）のＷ粉末を用い、このＷ粉末とＮｉ粉末などの副原料からなる原料粉末に少量の固形潤滑剤のみを添加した（有機バインダーは添加しない）上で、造粒することなく機械的に混合し、この混合粉体を従来法に較べて高い成形密度を有する成形体に成形し、この成形体を脱脂、焼結することにより、延性が高く且つ高精度な焼結タングステン基合金が得られることが判った。しかも、このような製造法によれば、一部又は全体の厚さ（肉厚）が０．５ｍｍ未満であるような薄物の焼結体についても容易に製造できることが判った。 (Iii) Therefore, as a result of studying a powder molding sintering method that does not use an organic binder, the conventional technique has become common sense to use W powder having a fine particle size (about 2 to 4 μm), whereas dare to do so. Using a W powder with a coarse particle size (7 μm or more), granulate after adding only a small amount of solid lubricant (without adding an organic binder) to the raw material powder consisting of this W powder and auxiliary materials such as Ni powder. Without mixing mechanically, this mixed powder is formed into a molded body having a higher molding density than the conventional method, and this molded body is degreased and sintered to achieve high ductility and high accuracy. It has been found that a tungsten-based alloy can be obtained. Moreover, according to such a manufacturing method, it was found that a thin sintered body having a partial or total thickness (wall thickness) of less than 0.5 mm can be easily manufactured.
本発明は、以上のような知見に基づきなされたもので、以下を要旨とするものである。
［1］Ｗを９０．０質量％以上含有し、残部がＣｕ、Ｆｅ及びＭｏの中から選ばれる１種以上、Ｎｉ及び不可避不純物からなり、炭素含有量が１２質量ppm以下、引張伸びが９％以上であることを特徴とする焼結タングステン基合金。
［2］上記［1］の焼結タングステン基合金において、Ｎｉを０．２〜９．５質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜９．５質量％含有することを特徴とする焼結タングステン基合金。
［3］上記［1］の焼結タングステン基合金において、Ｗを９６．０質量％以上含有し、残部がＣｕ、Ｆｅ及びＭｏの中から選ばれる１種以上、Ｎｉ及び不可避不純物からなり、密度が１８．４ｇ／ｃｍ３以上であることを特徴とする焼結タングステン基合金。
The present invention has been made on the basis of the above-described findings and has the following gist.
[1] Containing 90.0% by mass or more of W, with the balance being one or more selected from Cu, Fe and Mo, Ni and inevitable impurities, a carbon content of 12 mass ppm or less, and a tensile elongation of 9 %. A sintered tungsten-based alloy characterized by being at least%.
[2] In the sintered tungsten-based alloy of the above [1], 0.2 to 9.5% by mass of Ni and at least one selected from Cu, Fe and Mo are 0.2 to 9.5 in total. A sintered tungsten-based alloy characterized by containing a mass%.
[3] The sintered tungsten-based alloy according to [1] above, containing 96.0% by mass or more of W, with the balance being one or more selected from Cu, Fe and Mo, Ni and inevitable impurities, Is a sintered tungsten-based alloy, characterized in that it is 18.4 g / cm 3 or more.
［4］上記［3］の焼結タングステン基合金において、Ｎｉを０．２〜３．５質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜３．５質量％含有することを特徴とする焼結タングステン基合金。
［5］上記［1］〜［4］のいずれかの焼結タングステン基合金において、断面組織での空孔の面積率が１％未満であることを特徴とする焼結タングステン基合金。
［6］上記［1］〜［5］のいずれかの焼結タングステン基合金において、炭素含有量が５質量ppm未満、引張伸びが１５％以上であることを特徴とする焼結タングステン基合金。
［7］上記［1］〜［6］のいずれかの焼結タングステン基合金において、少なくとも一部の部位が０．１５ｍｍ以上０．５０ｍｍ未満の肉厚を有することを特徴とする焼結タングステン基合金。
[4] In the sintered tungsten-based alloy of the above [3], 0.2 to 3.5% by mass of Ni and one or more selected from Cu, Fe and Mo in total 0.2 to 3.5 A sintered tungsten-based alloy characterized by containing a mass%.
[5] The sintered tungsten-based alloy according to any one of the above [1] to [4], wherein the area ratio of pores in the cross-sectional structure is less than 1%.
[6] A sintered tungsten-based alloy according to any one of the above [1] to [5], wherein the carbon content is less than 5 ppm by mass and the tensile elongation is 15% or more.
[7] The sintered tungsten base alloy according to any one of the above [1] to [6], wherein at least a part has a thickness of 0.15 mm or more and less than 0.50 mm. alloy.
［8］ＦＳＳＳ平均粒径が７．０μｍ以上のＷ粉末の割合が９０．０質量％以上で、残部がＣｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末である原料粉末に、原料粉末と固形潤滑剤の合計量中での割合で０．１〜０．５質量％の固形潤滑剤を添加して（但し、有機バインダーは添加しない）機械的に混合した後、成形密度が１３ｇ／ｃｍ３以上となる成形圧で成形し、この成形体を還元性ガス雰囲気中又は不活性ガス雰囲気中で脱脂処理した後、還元性ガス雰囲気中又は不活性ガス雰囲気中で焼結することを特徴とする焼結タングステン基合金の製造方法。 [8] A raw material in which the proportion of W powder having an FSSS average particle size of 7.0 μm or more is 90.0% by mass or more, and the balance is one or more selected from Cu powder, Fe powder and Mo powder and Ni powder After adding 0.1 to 0.5 mass% solid lubricant in the ratio in the total amount of a raw material powder and a solid lubricant to a powder (however, an organic binder is not added), Molding is performed at a molding pressure at which the molding density is 13 g / cm 3 or more, and the compact is degreased in a reducing gas atmosphere or an inert gas atmosphere, and then fired in a reducing gas atmosphere or an inert gas atmosphere. A method for producing a sintered tungsten-based alloy, comprising: bonding.
［9］上記［8］の製造方法において、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末のＦＳＳＳ平均粒径が２０μｍ以下であり、原料粉末中のＮｉ粉末の割合が０．２〜９．５質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合が０．２〜９．５質量％であることを特徴とする焼結タングステン基合金の製造方法。
［10］上記［8］の製造方法において、原料粉末は、ＦＳＳＳ平均粒径が７．０μｍ以上のＷ粉末の割合が９６．０質量％以上で、残部がＣｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末であることを特徴とする焼結タングステン基合金の製造方法。
[9] In the production method of [8] above, the FSSS average particle size of one or more selected from Cu powder, Fe powder and Mo powder and Ni powder is 20 μm or less, and the ratio of Ni powder in the raw material powder 0.2 to 9.5% by mass, and the total ratio of one or more selected from Cu powder, Fe powder and Mo powder is 0.2 to 9.5% by mass. A method for producing a tungsten-based alloy.
[10] In the production method of [8] above, the raw material powder has a ratio of W powder having an FSSS average particle size of 7.0 μm or more of 96.0% by mass or more, and the balance is Cu powder, Fe powder and Mo powder. A method for producing a sintered tungsten-based alloy, comprising at least one selected from the group consisting of Ni powder and Ni powder.
［11］上記［10］の製造方法において、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末のＦＳＳＳ平均粒径が２０μｍ以下であり、原料粉末中のＮｉ粉末の割合が０．２〜３．５質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合が０．２〜３．５質量％であることを特徴とする焼結タングステン基合金の製造方法。
［12］上記［8］〜［11］のいずれかの製造方法において、焼結時の線収縮率が１１％以下であることを特徴とする焼結タングステン基合金の製造方法。
［13］上記［8］〜［12］のいずれかの製造方法において、成形体を６００〜１０００℃で脱脂処理した後、１４５０〜１５５０℃で焼結することを特徴とする焼結タングステン基合金の製造方法。
［14］上記［8］〜［13］のいずれかの製造方法において、少なくとも一部の部位が０．１５ｍｍ以上０．５０ｍｍ未満の肉厚を有する焼結体を得ることを特徴とする焼結タングステン基合金の製造方法。
[11] In the production method of [10], the FSSS average particle size of at least one selected from Cu powder, Fe powder and Mo powder and Ni powder is 20 μm or less, and the ratio of Ni powder in the raw material powder Is characterized in that the total proportion of one or more selected from the group consisting of 0.2 to 3.5 mass%, Cu powder, Fe powder and Mo powder is 0.2 to 3.5 mass% A method for producing a tungsten-based alloy.
[12] The method for producing a sintered tungsten-based alloy according to any one of the above [8] to [11], wherein a linear shrinkage rate during sintering is 11% or less.
[13] A sintered tungsten-based alloy according to any one of the above [8] to [12], wherein the compact is degreased at 600 to 1000 ° C. and then sintered at 1450 to 1550 ° C. Manufacturing method.
[14] In the production method according to any one of [8] to [13], a sintered body is obtained, wherein a sintered body having a thickness of at least a part of 0.15 mm or more and less than 0.50 mm is obtained. A method for producing a tungsten-based alloy.
本発明の焼結タングステン基合金は、延性が高く且つ高精度であるという優れた品質性能を有する。また、特に高Ｗ含有量とした場合には、高密度でありながら、延性が高く且つ高精度であるという優れた品質性能を有する。
また、本発明の製造方法によれば、そのような優れた品質性能を有する焼結タングステン基合金を安定して製造することができるとともに、薄物の焼結タングステン基合金も容易に製造することができる。さらに、従来法のような混練、造粒工程が不要であり、しかも脱脂時間も短くて済むため、製造コストを低減できる利点がある。
The sintered tungsten-based alloy of the present invention has excellent quality performance of high ductility and high accuracy. In particular, when the W content is high, it has an excellent quality performance of high density, high ductility and high accuracy.
Further, according to the manufacturing method of the present invention, a sintered tungsten-based alloy having such excellent quality performance can be stably manufactured, and a thin sintered tungsten-based alloy can be easily manufactured. it can. Further, there is an advantage that the manufacturing cost can be reduced because the kneading and granulating steps as in the conventional method are unnecessary and the degreasing time is short.
本発明の焼結タングステン基合金（以下、単に「焼結体」という場合がある）は、Ｗを９０．０質量％以上含有し、残部がＣｕ、Ｆｅ及びＭｏの中から選ばれる１種以上、Ｎｉ及び不可避不純物からなり、炭素含有量を１２質量ppm以下、引張伸びを９％以上とする。
Ｗが９０．０質量％未満では、錘等に必要とされる密度を確保できない。また、特に高密度の焼結タングステン基合金とする場合、好ましいＷ含有量は９６．０質量％以上であり、より好ましいＷ含有量は９６．５質量％以上であり、特に好ましいＷ含有量は９７．０質量％以上である。Ｗが９６．０質量％未満では、錘等として必要な１８．４ｇ／ｃｍ３以上の高密度が得られない。
The sintered tungsten-based alloy of the present invention (hereinafter sometimes referred to simply as “sintered body”) contains 90.0% by mass or more of W, and the balance is one or more selected from Cu, Fe and Mo. , Ni and inevitable impurities, the carbon content is 12 mass ppm or less, and the tensile elongation is 9% or more.
If W is less than 90.0% by mass, the density required for the weight or the like cannot be ensured. In addition, when a high-density sintered tungsten-based alloy is used, a preferable W content is 96.0% by mass or more, a more preferable W content is 96.5% by mass or more, and a particularly preferable W content is It is 97.0 mass% or more. When W is less than 96.0% by mass, a high density of 18.4 g / cm 3 or more necessary as a weight or the like cannot be obtained.
Ｎｉ、Ｃｕ、Ｆｅ、Ｍｏは、Ｗと合金化してより低温で液相となって結合相を生成させる成分であるが、本発明ではＮｉを含有し、さらにＣｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を含有する組成とする。ここで、Ｎｉは液相生成のための主要成分であり、Ｃｕ，Ｆｅ，Ｍｏは焼結温度を低くするために液相化温度を調整（低減）する成分である。 Ni, Cu, Fe, and Mo are components that are alloyed with W to form a liquid phase at a lower temperature to form a binder phase. In the present invention, Ni is contained, and further selected from Cu, Fe, and Mo. It is set as the composition containing 1 or more types. Here, Ni is a main component for generating a liquid phase, and Cu, Fe, and Mo are components for adjusting (reducing) the liquid phase temperature in order to lower the sintering temperature.
これら結合相生成成分の含有量は特に限定しないが、Ｎｉを０．２〜９．５質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜９．５質量％含有することが好ましい。Ｎｉ含有量が０．２質量％未満では、Ｎｉを添加することによる上述の効果が十分に得られず、一方、９．５質量％を超えると、所望の密度とするのに必要なＷ量が確保できなくなる。また、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上についても、その含有量が０．２質量％未満では、それらの１種以上を添加することによる上述の効果が十分に得られず、一方、９．５質量％を超えると、所望の密度とするのに必要なＷ量が確保できなくなる。ただし、延性を考慮すると、質量比でＮｉ／（Ｆｅ＋Ｃｕ＋Ｍｏ）を７／１〜３／７とすることが好ましい。 The content of these binder phase generation components is not particularly limited, but Ni is 0.2 to 9.5% by mass, and one or more selected from Cu, Fe and Mo is 0.2 to 9.5% in total. % Content is preferable. If the Ni content is less than 0.2% by mass, the above-mentioned effects due to the addition of Ni cannot be sufficiently obtained. Cannot be secured. Moreover, also about 1 or more types chosen from Cu, Fe and Mo, if the content is less than 0.2% by mass, the above-described effects by adding one or more of them cannot be sufficiently obtained, On the other hand, if it exceeds 9.5% by mass, the amount of W necessary to obtain a desired density cannot be secured. However, considering ductility, it is preferable that Ni / (Fe + Cu + Mo) is 7/1 to 3/7 in terms of mass ratio.
また、特に高密度の焼結タングステン基合金とするために、Ｗを９６．０質量％以上含有する場合には、Ｎｉを０．２〜３．５質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜３．５質量％含有することが好ましく、また、Ｗを９６．５質量％以上含有する場合には、Ｎｉを０．２〜３．０質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜３．０質量％含有することが好ましく、また、Ｗを９７．０質量％以上含有する場合には、Ｎｉを０．２〜２．５質量％、Ｃｕ、Ｆｅ及びＭｏの中から選ばれる１種以上を合計で０．２〜２．５質量％含有することが好ましい。これらの理由も上記と同様である。 Further, in order to obtain a particularly high-density sintered tungsten-based alloy, when W is contained in an amount of 96.0% by mass or more, Ni is 0.2 to 3.5% by mass, Cu, Fe, and Mo. It is preferable to contain at least one selected from 0.2 to 3.5% by mass, and when W is contained at 96.5% by mass or more, Ni is from 0.2 to 3.0% by mass. , Cu, Fe and Mo are preferably contained in a total of 0.2 to 3.0% by mass, and when W is contained in an amount of 97.0% by mass or more, Ni is added. It is preferable to contain 0.2 to 2.5 mass% in total of at least one selected from 0.2 to 2.5 mass%, Cu, Fe and Mo. These reasons are the same as above.
不可避不純物である炭素は、Ｗ粒の周辺に偏析して焼結体の延性を低下させるため、焼結体の炭素含有量を１２質量ppm以下とする。すなわち、炭素含有量が１２質量ppmを超えると焼結体の延性が低下する。また、延性をより高めるには、炭素量は８質量ppm以下が好ましく、５質量ppm未満が特に好ましい。例えば、Ｗが９６．０〜９７．０質量％の場合、炭素量を５質量ppm未満とすると、引張伸びを１５％以上とすることができる。 Carbon, which is an inevitable impurity, segregates around the W grains and lowers the ductility of the sintered body, so the carbon content of the sintered body is set to 12 mass ppm or less. That is, when the carbon content exceeds 12 mass ppm, the ductility of the sintered body is lowered. In order to further improve the ductility, the carbon content is preferably 8 ppm by mass or less, particularly preferably less than 5 ppm by mass. For example, when W is 96.0 to 97.0% by mass, the tensile elongation can be 15% or more when the carbon content is less than 5 ppm by mass.
有機バインダーを使用する従来法では脱脂に長時間を要するが、有機バインダーは分解しにくい性質であることから完全に除去することは難しい。このため従来法で製造される焼結体では、有機バインダーの一部が脱脂処理で分解除去されることなく不純物（炭素）として比較的高い濃度で焼結体に残留していたものである。本発明の焼結体は、そのような有機バインダー由来の不純物（炭素）が残留しないようにするため、有機バインダーを使用せず、その代わりに一般の鉄系粉末冶金の製造に使用されている固体潤滑剤を少量使用するだけで製造される。固体潤滑剤は脱脂処理で分解しやすく（脱脂時間も短時間で済む）、しかも少量添加であるため、炭素の残留を最小限に抑えることができる。したがって、本発明の焼結体に微量に含まれる炭素は、主に原料粉末と固体潤滑剤に由来するものである。例えば、Ｗ粉末には数ｐｐｍ程度の炭素が含まれ、また、副原料として使用されることがあるカーボニルＮｉやカーボニル鉄には、数百ｐｐｍ程度の炭素が含まれている。
以上のように本発明では、粉末成形焼結法において有機バインダーを使用せず、その代わりに少量の固体潤滑剤を使用し、且つ成形体に対して所定の脱脂処理を行うことにより、焼結体の炭素量を１２質量ppm以下（好ましくは８質量ppm以下、さらに好ましくは５質量ppm未満）とすることができる。
In the conventional method using an organic binder, it takes a long time to degrease, but it is difficult to completely remove the organic binder because it is difficult to decompose. For this reason, in the sintered body manufactured by the conventional method, a part of the organic binder remains in the sintered body at a relatively high concentration as impurities (carbon) without being decomposed and removed by the degreasing treatment. The sintered body of the present invention does not use an organic binder so that impurities (carbon) derived from such an organic binder do not remain, and is used instead for the production of general iron-based powder metallurgy. Manufactured with only a small amount of solid lubricant. The solid lubricant is easily decomposed by the degreasing process (the degreasing time is short), and since it is added in a small amount, the carbon residue can be minimized. Accordingly, the carbon contained in a trace amount in the sintered body of the present invention is mainly derived from the raw material powder and the solid lubricant. For example, W powder contains about several ppm of carbon, and carbonyl Ni and carbonyl iron, which are sometimes used as auxiliary materials, contain about several hundred ppm of carbon.
As described above, in the present invention, an organic binder is not used in the powder molding sintering method. Instead, a small amount of a solid lubricant is used, and a predetermined degreasing treatment is performed on the molded body, thereby sintering. The carbon content of the body can be 12 mass ppm or less (preferably 8 mass ppm or less, more preferably less than 5 mass ppm).
本発明の焼結体は、引張伸びが９％以上の延性を有する。引張伸びが低いと延性不足でサイジングで割れが生じやすくなる。引張伸びが９％以上であれば、様々な形状の部品のサイジングが可能となる。また、この観点からより好ましい引張伸びは１５％以上である。
本発明の焼結タングステン基合金は、密度を高めるために、焼結体の断面組織での空孔の面積率が１％未満であることが好ましい。この空孔の面積率は、次のようにして求める。すなわち、焼結体の任意の断面組織を撮像した１０個の４００倍ＳＥＭ画像をImage-Proによる画像解析により二値化処理して、視野に含まれる空孔の面積率を求め、１０個のＳＥＭ画像の平均値を空孔の面積率とする。
The sintered body of the present invention has a ductility with a tensile elongation of 9% or more. If the tensile elongation is low, cracking is likely to occur due to sizing due to insufficient ductility. If the tensile elongation is 9% or more, it is possible to size parts having various shapes. Further, from this viewpoint, more preferable tensile elongation is 15% or more.
In the sintered tungsten-based alloy of the present invention, the area ratio of pores in the cross-sectional structure of the sintered body is preferably less than 1% in order to increase the density. The area ratio of the holes is obtained as follows. That is, ten 400-times SEM images obtained by imaging an arbitrary cross-sectional structure of the sintered body are binarized by image analysis using Image-Pro to obtain the area ratio of holes included in the field of view. The average value of the SEM images is defined as the area ratio of the holes.
図１は、後述する実施例において製造された発明例（実施例No.３）と比較例（実施例No.１０）の焼結体の断面ＳＥＭ画像（左側、右上側のＳＥＭ画像）と、同じ比較例（実施例No.１０）の引張破面のＳＥＭ画像（右下側のＳＥＭ画像）である。なお、この引張破面のＳＥＭ画像は、空孔形成部分以外の部分の引張破面を撮像したものである。
比較例（実施例No.１０）の焼結体は、炭素含有量が高いため顕著な空孔を生じており、延性も劣っている。また、引張破面で伸びの悪い比較例の試料では、合金部（旧液相部）にディンプル（微小凹み）が観察されず、Ｗ粒子表面にＣが観察されており、このＣの残留が延性の低下に大きく影響しているものと考えられる。
FIG. 1 is a cross-sectional SEM image (left and upper right SEM images) of sintered bodies of invention examples (Example No. 3) and comparative examples (Example No. 10) manufactured in Examples described later, It is a SEM image (SEM image of the lower right side) of the tensile fracture surface of the same comparative example (Example No. 10). The SEM image of the tensile fracture surface is an image of the tensile fracture surface of a portion other than the hole forming portion.
Since the sintered body of the comparative example (Example No. 10) has a high carbon content, it produces remarkable voids and is inferior in ductility. Further, in the sample of the comparative example having a poor elongation due to the tensile fracture surface, no dimples (micro-dents) are observed in the alloy part (old liquid phase part), and C is observed on the surface of the W particles. This is thought to have a significant effect on the reduction in ductility.
また、本発明の焼結タングステン基合金を錘などのような特に高密度が要求される用途に適用する場合には、上述したようにＷ含有量を９６．０質量％以上（より好ましくは９６．５質量％以上、特に好ましくは９７．０質量％以上）とし、密度（焼結体密度）を１８．４ｇ／ｃｍ３以上とすることが好ましい。密度（焼結体密度）が１８．４ｇ／ｃｍ３未満では、特に自動巻き時計の回転重錘などのような重錘には適さない。また、高密度焼結タングステン基合金として、特に好ましい密度（焼結体密度）は１８．６ｇ／ｃｍ３以上である。 In addition, when the sintered tungsten-based alloy of the present invention is applied to an application requiring a particularly high density such as a weight, the W content is 96.0% by mass or more (more preferably 96% as described above). 0.5 mass% or more, particularly preferably 97.0 mass% or more), and the density (sintered body density) is preferably 18.4 g / cm 3 or more. If the density (sintered body density) is less than 18.4 g / cm 3, it is not particularly suitable for a weight such as a rotating weight of an automatic watch. Further, a particularly preferable density (sintered body density) as the high-density sintered tungsten-based alloy is 18.6 g / cm 3 or more.
次に、本発明の焼結タングステン基合金の製造方法について説明する。
この製造方法は、（i）粒径の粗いＷ粉末を用いる、（ii）このＷ粉末とＮｉ粉末などの副原料からなる原料粉末に、有機バインダーを添加せず、少量の固形潤滑剤のみを添加した上で、造粒することなく機械的に混合する、（iii）この混合粉体を比較的高い成形圧で所定の成形密度の成形体に成形し、この成形体を脱脂した後、焼結する、ことを特徴とする。ここで、上記（ii）、（iii）の基本は、バインダー造粒法（有機バインダーを添加して混合造粒する方法）を経ない粉末成形焼結法を行うということである。
Next, the manufacturing method of the sintered tungsten base alloy of this invention is demonstrated.
In this manufacturing method, (i) a coarse W powder is used, (ii) an organic binder is not added to the raw material powder composed of auxiliary materials such as this W powder and Ni powder, and only a small amount of solid lubricant is added. (Iii) The mixed powder is molded into a molded body having a predetermined molding density with a relatively high molding pressure, degreased, and then sintered. It is characterized by that. Here, the basis of the above (ii) and (iii) is to perform a powder molding sintering method that does not go through a binder granulation method (a method of adding and granulating an organic binder).
本発明の製造方法では、ＦＳＳＳ平均粒径（フィッシャー法による平均粒径）が７．０μｍ以上のＷ粉末の割合が９０．０質量％以上で、残部がＣｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末である原料粉末に、原料粉末と固形潤滑剤の合計量中での割合で０．１〜０．５質量％の固形潤滑剤を添加して（但し、有機バインダーは添加しない）機械的に混合した後、成形密度が１３ｇ／ｃｍ３以上となる成形圧で成形し、この成形体を還元性ガス雰囲気中又は不活性ガス雰囲気中で脱脂処理した後、還元性ガス雰囲気中又は不活性ガス雰囲気中で焼結し、焼結体を得る。 In the production method of the present invention, the proportion of W powder having an FSSS average particle size (Fischer method average particle size) of 7.0 μm or more is 90.0% by mass or more, and the balance is Cu powder, Fe powder and Mo powder. 0.1 to 0.5% by mass of a solid lubricant is added to the raw material powder that is one or more selected from the above and Ni powder in the total amount of the raw material powder and the solid lubricant (however, organic (Binder is not added) After mechanically mixing, molding is performed at a molding pressure at which the molding density is 13 g / cm 3 or more, and the compact is degreased in a reducing gas atmosphere or an inert gas atmosphere, and then reduced. Sintering is performed in an inert gas atmosphere or an inert gas atmosphere to obtain a sintered body.
原料粉末は、Ｗ粉末の割合が９０．０質量％以上で、残部がＣｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末からなり、また、原料粉末中のＮｉ粉末の割合は０．２〜９．５質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合は０．２〜９．５質量％であることが好ましい。これらの理由はさきに述べた通りである。 The raw material powder has a W powder ratio of 90.0% by mass or more, and the balance consists of one or more selected from Cu powder, Fe powder and Mo powder and Ni powder. The proportion is preferably 0.2 to 9.5 mass%, and the total proportion of one or more selected from Cu powder, Fe powder and Mo powder is preferably 0.2 to 9.5 mass%. These reasons are as described above.
また、高密度の焼結体を得るという観点からは、Ｗ粉末の割合は９６．０質量％以上が好ましく、９６．５質量％以上がより好ましく、９７．０質量％以上が特に好ましい。また、Ｗ粉末の割合を９６．０質量％以上とする場合には、Ｎｉ粉末の割合を０．２〜３．５質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合を０．２〜３．５質量％とすることが好ましい。また、Ｗ粉末の割合を９６．５質量％以上とする場合には、Ｎｉ粉末の割合を０．２〜３．０質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合を０．２〜３．０質量％とすることが好ましい。また、Ｗ粉末の割合を９７．０質量％以上とする場合には、Ｎｉ粉末の割合を０．２〜２．５質量％、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上の合計の割合を０．２〜２．５質量％とすることが好ましい。これらの理由も上記と同様である。 Further, from the viewpoint of obtaining a high-density sintered body, the proportion of the W powder is preferably 96.0% by mass or more, more preferably 96.5% by mass or more, and particularly preferably 97.0% by mass or more. When the proportion of the W powder is 96.0% by mass or more, the proportion of the Ni powder is 0.2 to 3.5% by mass, one or more selected from Cu powder, Fe powder and Mo powder. The total ratio of is preferably 0.2 to 3.5% by mass. When the proportion of W powder is 96.5% by mass or more, the proportion of Ni powder is 0.2 to 3.0% by mass, one or more selected from Cu powder, Fe powder and Mo powder. It is preferable to make the ratio of the total of 0.2-3.0 mass%. When the proportion of the W powder is 97.0% by mass or more, the proportion of the Ni powder is 0.2 to 2.5% by mass, one or more selected from Cu powder, Fe powder and Mo powder. The total ratio of is preferably 0.2 to 2.5% by mass. These reasons are the same as above.
Ｗ粉末のＦＳＳＳ平均粒径は７．０μｍ以上とする。Ｗ粉末のＦＳＳＳ平均粒径が７．０μｍ未満では、バインダー造粒法を経ない粉末成形焼結法において、金型に粉末を充填する際の流動性を確保できず、連続した成形ができない。
表１は、ＦＳＳＳ平均粒径が異なるＷ粉末の流動性を示している。この流動性の測定は、ＪＩＳ Ｚ２５０２（２０１２）金属粉−流動測定法に準拠したが、漏斗径はφ５ｍｍを使用し、かつ棚釣りを起こしやすい粉末であることから、バイブレーターにより若干の上下振動を与えながら測定した。
The FSSS average particle diameter of W powder shall be 7.0 micrometers or more. When the FSSS average particle size of the W powder is less than 7.0 μm, in the powder molding and sintering method that does not pass through the binder granulation method, the fluidity when filling the powder into the mold cannot be secured, and continuous molding cannot be performed.
Table 1 shows the fluidity of W powders with different FSSS average particle sizes. This fluidity measurement was in accordance with JIS Z2502 (2012) metal powder-flow measurement method, but the diameter of the funnel was 5mm, and it was a powder that would easily cause shelf fishing. Measured while giving.
表１によれば、Ｗ粉末のＦＳＳＳ平均粒径が７．０μｍ以上であれば、流動度６sec/50g以下であり、バインダー造粒法を経ない粉末成形焼結法でも、必要な流動性及び成形性を確保することできる。また、この流動性及び成形性の観点から、より好ましいＷ粉末のＦＳＳＳ平均粒径は８．０μｍ以上であり、さらに好ましくは８．５μｍ以上である。なお、Ｗ粉末の粒径が大きすぎると焼結密度を高めにくくなるので、Ｗ粉末のＦＳＳＳ平均粒径は２０μｍ程度を上限とすることが好ましい。 According to Table 1, if the FSSS average particle diameter of W powder is 7.0 μm or more, the fluidity is 6 sec / 50 g or less, and the required fluidity and Formability can be ensured. Further, from the viewpoint of fluidity and moldability, the FSSS average particle size of the W powder is more preferably 8.0 μm or more, and even more preferably 8.5 μm or more. In addition, since it will become difficult to raise a sintered density if the particle size of W powder is too large, it is preferable that the FSSS average particle diameter of W powder sets about 20 micrometers as an upper limit.
また、Ｃｕ粉末、Ｆｅ粉末及びＭｏ粉末の中から選ばれる１種以上とＮｉ粉末のＦＳＳＳ平均粒径は２０μｍ以下が好ましく、１０μｍ以下が特に好ましい。これら副原料のＦＳＳＳ平均粒径が２０μｍを超えると焼結組織が不均一になりやすい。また、これら副原料のＦＳＳＳ平均粒径の下限は特にないが、通常、１μｍ程度が下限となる。これら副原料の粒径については、従来法で使用されるものと基本的に変わらない。 Further, the FSSS average particle size of at least one selected from Cu powder, Fe powder and Mo powder and Ni powder is preferably 20 μm or less, and particularly preferably 10 μm or less. If the FSSS average particle size of these auxiliary materials exceeds 20 μm, the sintered structure tends to be non-uniform. In addition, there is no particular lower limit on the FSSS average particle size of these auxiliary materials, but usually about 1 μm is the lower limit. The particle size of these auxiliary materials is basically the same as that used in the conventional method.
原料粉末に固形潤滑剤を添加して機械的に混合（例えば、Ｖブレンダーによる混合）した後、この混合粉末を金型を用いて所定の成形圧で成形し、成形密度が１３ｇ／ｃｍ３以上の成形体とする。
固形潤滑剤としては、鉄系粉末冶金に一般的に使用されるものを用いることができる。例えば、ステアリン酸亜鉛などの金属石鹸、エチレンビスステアリン酸アミド、ケノルーブ、アクラワックスなどが挙げられ、これらの１種以上を用いることができる。
固形潤滑剤も添加量が多すぎると、脱脂処理後に未分解の炭素が残留しやすいので、固形潤滑剤の添加量は、原料粉末と固形潤滑剤の合計量中での割合で０．１〜０．５質量％とする。この添加量であれば、必要な型潤滑性が得られる一方で、高い成形密度でも脱脂処理時に分解ガスが容易に成形体外に排出され、炭素の残留が抑えられる。
After adding a solid lubricant to the raw material powder and mechanically mixing (for example, mixing with a V blender), this mixed powder is molded at a predetermined molding pressure using a mold, and the molding density is 13 g / cm 3 or more. A molded body of
As the solid lubricant, those generally used in iron-based powder metallurgy can be used. For example, metal soaps such as zinc stearate, ethylene bis-stearic acid amide, kenolube, and accra wax can be used, and one or more of these can be used.
If the solid lubricant is added too much, undecomposed carbon is likely to remain after the degreasing treatment, so the amount of solid lubricant added is 0.1 to 0.1 in terms of the total amount of raw material powder and solid lubricant. 0.5% by mass. With this added amount, the necessary mold lubricity can be obtained, while cracking gas can be easily discharged out of the molded body during degreasing even at a high molding density, and carbon residue can be suppressed.
また、本発明では有機バインダーを使用しないため、成形体の成形密度が１３ｇ／ｃｍ３未満では成形体の強度が小さく、ハンドリングができない。また、焼結時の収縮率が大きくなり、高精密の焼結体が得られない。なお、金型の強度や寿命の面から１７ｇ／ｃｍ３程度が成形密度の実質的な上限となる。
成形体の成形密度を１３ｇ／ｃｍ３以上とするためには、成形圧を４．０ｔ／ｃｍ２以上とすることが好ましい。図２は、高密度焼結タングステン基合金を製造するために、粗い粒径（ＦＳＳＳ平均粒径７．０μｍ以上）のＷ粉末を主体とする原料粉末に少量の固形潤滑剤のみを添加した（有機バインダーは添加しない）上で、造粒することなく機械的に混合し、この混合粉体を成形した際において、その成形圧と成形体の成形密度との関係を調べた結果を示している。この試験では、ＦＳＳＳ平均粒径が１０〜１２μｍのＷ粉末と副原料（Ｎｉ，Ｆｅ）からなる原料粉末に０．３〜０．５質量％（外掛け量）の固形潤滑剤（ステアリング酸亜鉛）を添加した。図２によれば、成形圧を４．０ｔ／ｃｍ２以上とすれば、概ね成形体の成形密度を１３ｇ／ｃｍ３以上にできることが判る。
Moreover, since an organic binder is not used in the present invention, if the molding density of the compact is less than 13 g / cm 3 , the strength of the compact is small and handling is not possible. In addition, the shrinkage rate during sintering increases, and a highly precise sintered body cannot be obtained. From the standpoint of mold strength and life, about 17 g / cm 3 is the substantial upper limit of the molding density.
In order to set the molding density of the molded body to 13 g / cm 3 or more, it is preferable to set the molding pressure to 4.0 t / cm 2 or more. FIG. 2 shows that in order to produce a high-density sintered tungsten-based alloy, only a small amount of a solid lubricant was added to a raw material powder mainly composed of W powder having a coarse particle size (FSSS average particle size of 7.0 μm or more) ( This shows the result of investigating the relationship between the molding pressure and the molding density when this mixed powder was molded by mechanical mixing without granulation. . In this test, 0.3 to 0.5% by mass (outer coating amount) of a solid lubricant (zinc steering acid) was added to a raw material powder composed of W powder having an FSSS average particle size of 10 to 12 μm and auxiliary raw materials (Ni, Fe). ) Was added. According to FIG. 2, it can be seen that if the molding pressure is 4.0 t / cm 2 or more, the molding density of the molded body can be generally 13 g / cm 3 or more.
成形体の脱脂処理は、還元性ガス雰囲気中又は不活性ガス雰囲気中で行われるが、特に水素雰囲気又は水素−窒素雰囲気中において６００〜１０００℃で行うことが好ましい。また、成形体の焼結は、還元性ガス雰囲気中又は不活性ガス雰囲気中で行われるが、特に水素雰囲気中において１４５０〜１５５０℃で行うことが好ましい。
本発明の製造方法では、有機バインダーを使用せず、その代わりに脱脂で分解しやすい固体潤滑剤を使用し、しかも少量添加であるため、脱脂処理後の炭素の残留を最小限に抑えることができる。また、脱脂時間についても、有機バインダーを使用する従来法（プレス成形法）では５〜６時間を要するのに対して、本発明法ではごく短時間（３０分〜１時間程度）で済む利点がある。
The degreasing treatment of the molded body is performed in a reducing gas atmosphere or an inert gas atmosphere, and it is particularly preferable to perform the degreasing treatment at 600 to 1000 ° C. in a hydrogen atmosphere or a hydrogen-nitrogen atmosphere. Moreover, although sintering of a molded object is performed in a reducing gas atmosphere or an inert gas atmosphere, it is preferable to carry out at 1450-1550 degreeC especially in a hydrogen atmosphere.
In the production method of the present invention, an organic binder is not used, instead a solid lubricant that is easily decomposed by degreasing is used, and a small amount is added, so that carbon residue after degreasing can be minimized. it can. In addition, the degreasing time is 5 to 6 hours in the conventional method using an organic binder (press molding method), whereas the method of the present invention has an advantage that only a very short time (about 30 minutes to 1 hour) is required. is there.
本発明の製造方法では、成形体の成形密度が１３ｇ／ｃｍ３以上であるため、焼結時の線収縮率を小さくすることができ、高精度の焼結体を製造できるが、特に焼結時の線収縮率が１１％以下であることが好ましい。成形焼結時の線収縮率が１１％以下であれば、例えば、自動巻き時計の回転重錘のようなリング状の製品でも大きな歪みが生じることなく製造が可能となる。高精度の点においては、線収縮率は小さいほど好ましいことから、なるべく成形密度は高いほうが好ましいが、それに比例して成形圧を高くする必要があり、形状によっては高い成形圧が金型の寿命に影響を与える可能性もある。一般的には、成形圧を７ｔ／ｃｍ３以上とし、線収縮率を９％以下とすることがより好ましい。 In the manufacturing method of the present invention, since the molding density of the molded body is 13 g / cm 3 or more, the linear shrinkage rate during sintering can be reduced, and a highly accurate sintered body can be manufactured. It is preferable that the linear shrinkage rate is 11% or less. If the linear shrinkage rate during molding and sintering is 11% or less, for example, even a ring-shaped product such as a rotating weight of an automatic timepiece can be manufactured without causing large distortion. In terms of high accuracy, the smaller the linear shrinkage rate, the better. Therefore, it is preferable that the molding density be as high as possible. May also affect In general, it is more preferable that the molding pressure is 7 t / cm 3 or more and the linear shrinkage rate is 9% or less.
得られた焼結体には、形状によって精度向上のため冷間矯正（サイジング）を施してもよい。なお、本発明で得られる焼結体は延性が高いため、延性改善のための熱処理を行う必要はない。
従来法は、Ｗ粉末と副原料に有機バインダーを添加して混練し、ＭＩＭ（混合工程設備が必要で且つ脱脂時間が長くコスト高である）で製造するか、流動性や成形性を確保するためスプレードライヤーなどで造粒した後、プレス成形する。そして、有機バインダーを使用しているため、脱脂時間を十分にとる必要がある。これに対して本発明の製造方法では、従来法のような混練、造粒工程が不要であり、しかも脱脂時間も短くて済むため、製造コストが低減できる利点がある。
The obtained sintered body may be subjected to cold correction (sizing) for improving accuracy depending on the shape. In addition, since the sintered compact obtained by this invention has high ductility, it is not necessary to perform the heat processing for ductility improvement.
In the conventional method, an organic binder is added to the W powder and the auxiliary material and kneaded, and manufactured by MIM (mixing process equipment is required and the degreasing time is long and expensive), or fluidity and moldability are ensured. Therefore, it is granulated with a spray dryer and then press molded. And since the organic binder is used, it is necessary to take sufficient degreasing time. On the other hand, the production method of the present invention does not require kneading and granulation steps as in the conventional method, and has a merit that the production cost can be reduced because the degreasing time can be shortened.
また、本発明の製造方法は、上述した（i）〜（iii）の特徴を有する粉末成形焼結法であり、原料粉末を造粒しないため薄肉化が可能であるとともに、薄物であってもハンドリング可能な成形体に成形でき、しかも液相焼結時の収縮率も小さくできるので、少なくとも一部の部位の肉厚（厚み）が０．５０ｍｍ未満であるような焼結体も容易に製造することができる。ここで、０．５０ｍｍ未満の肉厚とは、図５、図６に示すように焼結体全体の肉厚（厚み）が０．５０ｍｍ未満である場合の他に、例えば、図３及び図４に示すように焼結体の一部の部位の肉厚（厚み）が０．５０ｍｍ未満である場合を含む。本発明では、肉厚（厚み）０．１５ｍｍ程度までは製造が可能である。 Further, the production method of the present invention is a powder molding sintering method having the above-mentioned features (i) to (iii), and since the raw material powder is not granulated, it can be thinned, Since it can be formed into a handleable molded body and the shrinkage rate during liquid phase sintering can be reduced, it is easy to manufacture a sintered body with a thickness (thickness) of at least a part of less than 0.50 mm. can do. Here, the thickness of less than 0.50 mm means that the thickness (thickness) of the entire sintered body is less than 0.50 mm as shown in FIGS. 5 and 6, for example, FIG. 3 and FIG. 4 includes a case where the thickness (thickness) of a part of the sintered body is less than 0.50 mm. In the present invention, manufacturing is possible up to a thickness (thickness) of about 0.15 mm.
高精度で高い延性を有する本発明の焼結タングステン基合金は種々の用途に適用でき、特に高密度のものは、例えば、自動巻き時計の回転重錘、放射線遮蔽材、携帯電話の振動呼び出し振動モータの振動子、その他精密機器の錘、ゲーム機の振動発生装置用錘、ゴルフなどのレジャー用錘などのような用途に好適である。 The sintered tungsten-based alloy of the present invention having high accuracy and high ductility can be applied to various applications, and particularly high-density ones such as a rotating weight of a self-winding watch, a radiation shielding material, and a vibration ringing vibration of a mobile phone. It is suitable for applications such as motor vibrators, weights of other precision devices, weights for vibration generators of game machines, and weights for leisure such as golf.
本発明例と比較例の製造条件（使用した原料粉末の粒径及び配合量、固形潤滑剤の種類及び添加量、粉末成形焼結条件）を表２〜表５に示す。
原料粉末（Ｗ粉末＋Ｎｉ粉末などの結合相形成成分）に固形潤滑剤を添加してＶブレンダーで機械的に混合した後、成形して所定の成形密度の成形体を得た。この成形体を水素雰囲気中で脱脂処理（６００℃×３０分間保持した後、１０００℃×３０分間保持）した後、水素雰囲気中で焼結（１５００℃×２時間保持）して焼結体を得た。
Tables 2 to 5 show the production conditions of the inventive examples and comparative examples (particle size and blending amount of raw material powder used, type and addition amount of solid lubricant, powder molding sintering conditions).
A solid lubricant was added to the raw material powder (a binder phase forming component such as W powder + Ni powder) and mechanically mixed with a V blender, and then molded to obtain a molded body having a predetermined molding density. The molded body was degreased in a hydrogen atmosphere (held at 600 ° C. for 30 minutes and then held at 1000 ° C. for 30 minutes), and then sintered in a hydrogen atmosphere (held at 1500 ° C. for 2 hours) to obtain a sintered body. Obtained.
成形体の成形密度、焼結時の線収縮率、焼結体の密度、焼結体の断面ＳＥＭ画像での空孔の面積率、焼結体の炭素含有量、焼結体の引張伸びを、次のように算出又は測定した。それらの結果を表２〜表５に示す。
成形体の成形密度と焼結体の密度はアルキメデス法で測定した。焼結時の線収縮率は、成形密度と焼結密度の比を線収縮率に換算して求めた。焼結体の断面ＳＥＭ画像での空孔の面積率は、さきに述べた方法で測定した。焼結体の炭素量は、燃焼−赤外吸収法で測定した。焼結体の引張伸びは、ＪＩＳ Ｚ２５５０（２０００）機械構造部品用焼結材料に記載の圧粉体作製用押型を使用して試料を作製し、引張速度０．５ｍｍ／ｍiｎにて標点間距離の変化を求めた。
The compact density of the compact, the linear shrinkage ratio during sintering, the density of the sintered compact, the area ratio of pores in the cross-sectional SEM image of the sintered compact, the carbon content of the sintered compact, and the tensile elongation of the sintered compact The calculation or measurement was performed as follows. The results are shown in Tables 2-5.
The molding density of the molded body and the density of the sintered body were measured by Archimedes method. The linear shrinkage rate at the time of sintering was obtained by converting the ratio between the molding density and the sintered density into the linear shrinkage rate. The area ratio of pores in the cross-sectional SEM image of the sintered body was measured by the method described above. The carbon content of the sintered body was measured by a combustion-infrared absorption method. The tensile elongation of the sintered body was measured using a green compact manufacturing die described in JIS Z2550 (2000) Sintered material for machine structural parts, and between the gauge points at a tensile speed of 0.5 mm / min. The change in distance was determined.
表２〜表５の実施例のうちのNo.２０（本発明例）と同じ製造条件でリング状でその一部に貫通穴のある電子部品錘となる焼結体を製造した。したがって、この焼結体の組成・物性・性状はNo.２０（本発明例）と同等である。図３、図４は、この焼結体の一部の部位を撮像したＳＥＭ画像である。画像に写っている貫通穴は成形体として形成されたものであり、その孔が形成された部位の肉厚は０．１７５ｍｍである。したがって、本発明法により、一部の部位が０．１７５ｍｍの肉厚を有する焼結体が得られたことになる。 The sintered compact used as the electronic component weight which has a ring shape and the through-hole in the one part was manufactured on the same manufacturing conditions as No. 20 (invention example) of the Example of Table 2-Table 5. FIG. Therefore, the composition, physical properties and properties of this sintered body are the same as No. 20 (example of the present invention). 3 and 4 are SEM images obtained by imaging a part of the sintered body. The through-hole shown in the image is formed as a molded body, and the thickness of the portion where the hole is formed is 0.175 mm. Therefore, according to the method of the present invention, a sintered body having a thickness of 0.175 mm at a part of the part is obtained.
表２〜表５の実施例のうちのNo.２４（本発明例）と同じ製造条件で円盤状の電子部品錘となる焼結体を製造した。したがって、この焼結体の組成・物性・性状はNo.２４（本発明例）と同等である。図５は、その焼結体を撮像したＳＥＭ画像であり、直径１．８ｍｍφ、厚さ０．３ｍｍの円盤状の焼結体である。したがって、本発明法により、全体の厚さが０．３ｍｍの焼結体が得られたことになる。 The sintered compact used as the disk-shaped electronic component weight was manufactured on the same manufacturing conditions as No. 24 (invention example) of the Examples in Tables 2 to 5. Therefore, the composition, physical properties, and properties of this sintered body are the same as No. 24 (example of the present invention). FIG. 5 is an SEM image obtained by imaging the sintered body, which is a disk-shaped sintered body having a diameter of 1.8 mmφ and a thickness of 0.3 mm. Therefore, a sintered body having an overall thickness of 0.3 mm was obtained by the method of the present invention.
表２〜表５の実施例のうちのNo.２３（本発明例）と同じ製造条件で円盤状の電子部品錘となる焼結体を製造した。したがって、この焼結体の組成・物性・性状はNo.２３（本発明例）と同等である。図６は、その焼結体を撮像したＳＥＭ画像であり、直径１．８ｍｍφ、厚さ０．４ｍｍの円盤状の焼結体である。したがって、本発明法により、全体の厚さが０．４ｍｍの焼結体が得られたことになる。 The sintered compact used as the disk-shaped electronic component weight was manufactured on the same manufacturing conditions as No. 23 (example of this invention) of the Example of Table 2-Table 5. FIG. Therefore, the composition, physical properties, and properties of this sintered body are the same as No. 23 (example of the present invention). FIG. 6 is an SEM image obtained by imaging the sintered body, which is a disk-shaped sintered body having a diameter of 1.8 mmφ and a thickness of 0.4 mm. Therefore, a sintered body having a total thickness of 0.4 mm is obtained by the method of the present invention.
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| CN110079690A (en) * | 2019-06-14 | 2019-08-02 | 安泰天龙钨钼科技有限公司 | A kind of high molybdenum content molybdenum-copper and preparation method thereof |
| CN110093544A (en) * | 2019-05-30 | 2019-08-06 | 陕西理工大学 | The preparation method of multistage strip crystalline substance tungsten alloy material |
| CN110885957A (en) * | 2019-12-20 | 2020-03-17 | 西安华山钨制品有限公司 | Process for improving density of tungsten-nickel-copper alloy |
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