JP2020164991A - Pressurized sintered body and its manufacturing method - Google Patents

Pressurized sintered body and its manufacturing method Download PDF

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JP2020164991A
JP2020164991A JP2020051224A JP2020051224A JP2020164991A JP 2020164991 A JP2020164991 A JP 2020164991A JP 2020051224 A JP2020051224 A JP 2020051224A JP 2020051224 A JP2020051224 A JP 2020051224A JP 2020164991 A JP2020164991 A JP 2020164991A
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sintered body
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敬 村上
Takashi Murakami
敬 村上
敦 是永
Atsushi Korenaga
敦 是永
大花 継頼
Tsuguyori Ohana
継頼 大花
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National Institute of Advanced Industrial Science and Technology AIST
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Abstract

To provide a cermet type pressurized sintered body that maintains high mechanical strength even under a temperature from room temperature to about 1000°C, and does not damage a toughness value at room temperature.SOLUTION: Provided is a pressurized sintered body having Vickers harness Hv of 1500 or larger at room temperature, by bonding hard phase particles mainly made of Ti(C,N) with a metallic bonding phase made of metal. An average particle size of the hard phase particle is set to 2 μm or smaller, a bonding phase made of a high melting point metal of 2000°C or higher belonging to group 5 or group 6 is contained at a ratio of 10 to 70% by mass%, and high temperature Vickers hardness at 1000°C is rendered Hv1200 or larger.SELECTED DRAWING: Figure 1

Description

本発明は、主としてTi(C,N)からなる硬質相粒子を金属結合相にて結合したサーメット系の加圧焼結体及びその製造方法に関し、特に、高温強度により優れる加圧焼結体及びその製造方法に関する。 The present invention relates to a cermet-based pressure sintered body in which hard phase particles mainly composed of Ti (C, N) are bonded in a metal-bonded phase and a method for producing the same, and in particular, a pressure sintered body having superior high-temperature strength. Regarding the manufacturing method.

高強度ステンレス鋼、ハイパーシルミン及びチタン合金などの合金材料や、繊維強化プラスチック(FRP)のような複合材料が多くの機械部材に用いられている。かかる部材を機械加工するための工具材料については、過酷な使用環境となり得ることから、熱的及び化学的に安定であること、熱伝導率の高いこと、靭性の高いこと、高温で高い強度(硬さ)を有すること、などを要求される。このような耐摩耗性工具や切削工具のための工具材料としては、ダイヤモンド、立方晶窒化ホウ素(CBN)、WC(タングステンカーバイド)系超硬合金などが用いられており、特に、TiCからなる硬質相をNi及びCoなどの結合相で結合した加圧成形体であるサーメットが広く知られている。 Alloy materials such as high-strength stainless steel, hypersilmin and titanium alloys, and composite materials such as fiber reinforced plastics (FRP) are used in many mechanical components. Tool materials for machining such members can be used in harsh environments, so they are thermally and chemically stable, have high thermal conductivity, have high toughness, and have high strength at high temperatures. It is required to have hardness). As a tool material for such wear-resistant tools and cutting tools, diamond, cubic boron nitride (CBN), WC (tungsten carbide) cemented carbide and the like are used, and in particular, hard made of TiC. Cermet, which is a pressure-molded body in which the phases are bonded with a bonded phase such as Ni and Co, is widely known.

例えば、特許文献1では、TiCサーメットの機械強度をより高めるべく、硬質相にTiNを加えたTi(C,N)サーメットを開示している。硬質相は、Ti(C,N)からなる芯部と、W、Mo、Ta及びNbのうちの1種以上とTiとの複合化合物からなる周辺部と、から構成される有芯構造として、周辺部内には硬さや靭性、耐熱衝撃性を向上させるためのTiC微粒子を分散させるとしている。これにより機械強度、特に、靱性を大きく向上させるとしている。ここで、結合相は5〜30重量%の割合で与えられるが、結合相が少ないと焼結性を低下させることから靱性の低下、結果として、耐欠損性を損なうとしている。一方、結合相が多いと、相対的に硬質相の割合が低下し耐摩耗性及び耐塑性変形性を低下させるとしている。 For example, Patent Document 1 discloses a Ti (C, N) cermet in which TiN is added to a hard phase in order to further increase the mechanical strength of the TiC cermet. The hard phase has a core structure composed of a core portion made of Ti (C, N) and a peripheral portion made of a composite compound of one or more of W, Mo, Ta and Nb and Ti. TiC fine particles for improving hardness, toughness, and thermal shock resistance are dispersed in the peripheral portion. It is said that this will greatly improve mechanical strength, especially toughness. Here, the bonded phase is given in a proportion of 5 to 30% by weight, but if the bonded phase is small, the sinterability is lowered, so that the toughness is lowered, and as a result, the fracture resistance is impaired. On the other hand, if there are many bonded phases, the proportion of the hard phase is relatively reduced, and the wear resistance and the plastic deformation resistance are lowered.

サーメットにおける硬質相の粒子を結合する結合相としては、一般的に、CoやNiが用いられているが、上記したように、結合相は耐摩耗性などに影響を与える。そこで、結合相の強度をより高めるための提案もなされている。 Co and Ni are generally used as the bonding phase for bonding the hard phase particles in the cermet, but as described above, the bonding phase affects the wear resistance and the like. Therefore, a proposal has been made to further increase the strength of the bound phase.

例えば、特許文献2では、Co中にWとCoの複合炭化物からなる微細析出分散硬化相を与えた金属結合相を用いたTi(C,N)サーメットを開示している。高熱発生を伴う高速切削に用いた場合にも、優れた耐塑性変形性、耐熱衝撃性、耐欠損性を示し、長期に亘って優れた耐摩耗性を発揮するとしている。 For example, Patent Document 2 discloses a Ti (C, N) cermet using a metal-bonded phase in which a fine precipitation-dispersed cured phase composed of a composite carbide of W and Co is provided in Co. Even when used for high-speed cutting accompanied by high heat generation, it exhibits excellent plastic deformation resistance, thermal shock resistance, and fracture resistance, and is said to exhibit excellent wear resistance over a long period of time.

特開2008−156756号公報Japanese Unexamined Patent Publication No. 2008-156756 特開2009−248237号公報JP-A-2009-248237

上記したように、主としてTi(C,N)からなる硬質相粒子を金属結合相にて結合したサーメットは、優れた耐塑性変形性、耐熱衝撃性、耐欠損性を示し、長期に亘って優れた耐摩耗性を有する。一方、近年、より過酷な機械加工への適用も求められており、特に、より高温での機械強度の向上が求められている。 As described above, the cermet in which hard phase particles mainly composed of Ti (C, N) are bonded in a metal bonding phase exhibits excellent plastic deformation resistance, thermal shock resistance, and fracture resistance, and is excellent for a long period of time. Has abrasion resistance. On the other hand, in recent years, application to more severe machining is also required, and in particular, improvement of machine strength at a higher temperature is required.

本発明は、かかる状況に鑑みてなされたものであって、その目的とするところは、室温から1000℃程度の温度であっても高い機械強度を維持するとともに、室温における靱性値を損なわないサーメット系の加圧焼結体及びその製造方法を提供することにある。 The present invention has been made in view of such a situation, and an object of the present invention is a cermet that maintains high mechanical strength even at a temperature of about 1000 ° C. from room temperature and does not impair the toughness value at room temperature. It is an object of the present invention to provide a pressure sintered body of a system and a method for producing the same.

本発明による加圧焼結体は、主としてTi(C,N)からなる硬質相粒子を金属からなる金属結合相にて結合し室温におけるビッカース硬さをHv1500以上とした加圧焼結体であって、前記硬質相粒子の平均粒径を2μm以下とするとともに、5族又は6族に属する2000℃以上の高融点金属からなる前記結合相を質量%で10〜70%の割合で含み、1000℃における高温ビッカース硬さをHv1200以上としたことを特徴とする。 The pressure sintered body according to the present invention is a pressure sintered body in which hard phase particles mainly composed of Ti (C, N) are bonded by a metal bonding phase composed of a metal to have a Vickers hardness of Hv1500 or more at room temperature. The average particle size of the hard phase particles is 2 μm or less, and the bonded phase made of a refractory metal of 2000 ° C. or higher belonging to Group 5 or Group 6 is contained in a proportion of 10 to 70% by mass, 1000. It is characterized in that the high temperature Vickers hardness at ° C. is Hv1200 or more.

かかる発明によれば、室温から1000℃程度の温度であっても高い機械強度を維持することができ、室温においての靱性値も損なわない。 According to such an invention, high mechanical strength can be maintained even at a temperature of about 1000 ° C. from room temperature, and the toughness value at room temperature is not impaired.

上記した発明において、室温でのヤング率を400GPa以上としたことを特徴としてもよい。また、室温での破壊靱性値を4MPa・m1/2以上としたことを特徴としてもよい。かかる発明によれば、室温において高い機械強度を維持できる。 The invention described above may be characterized in that the Young's modulus at room temperature is 400 GPa or more. Further, it may be characterized in that the fracture toughness value at room temperature is 4 MPa · m 1/2 or more. According to such an invention, high mechanical strength can be maintained at room temperature.

上記した発明において、質量%でMoを10〜50%の割合で含むことを特徴としてもよい。また、質量%でWを10〜60%の割合で含むことを特徴としてもよい。また、質量%でTaを10〜60%の割合で含むことを特徴としてもよい。また、質量%でNbを10〜50%の割合で含むことを特徴としてもよい。かかる発明によれば、室温から1000℃程度の温度において高い機械強度をより確実に得ることができる。 The invention described above may be characterized in that Mo is contained in a proportion of 10 to 50% by mass. Further, it may be characterized in that W is contained in a proportion of 10 to 60% in mass%. Further, it may be characterized by containing Ta in a proportion of 10 to 60% by mass. Further, it may be characterized in that Nb is contained in a proportion of 10 to 50% in mass%. According to such an invention, high mechanical strength can be more reliably obtained at a temperature of about 1000 ° C. from room temperature.

また、本発明による加圧焼結体の製造方法は、主としてTi(C,N)からなる硬質相粒子を金属からなる金属結合相にて結合し室温及び1000℃におけるビッカース硬さをそれぞれHv1500以上及びHv1200以上とする加圧焼結体の製造方法であって、2μm以下の平均粒径のTi(C,N)からなる粒子に対して、2μm以下の平均粒径の5族又は6族に属する2000℃以上の高融点金属からなる粒子を質量%で10〜70%の割合で加え混合する混合工程と、1700℃以上且つ前記高融点金属の融点以下の温度で加圧する加圧焼結工程と、を含むことを特徴とする。 Further, in the method for producing a pressure sintered body according to the present invention, hard phase particles mainly composed of Ti (C, N) are bonded by a metal bonding phase composed of a metal, and the Vickers hardness at room temperature and 1000 ° C. is Hv1500 or more, respectively. And a method for producing a pressure sintered body having an Hv of 1200 or more, in which particles composed of Ti (C, N) having an average particle size of 2 μm or less are classified into Group 5 or Group 6 having an average particle size of 2 μm or less. A mixing step of adding and mixing particles made of a refractory metal having a melting point of 2000 ° C. or higher at a ratio of 10 to 70% by mass, and a pressure sintering step of pressurizing at a temperature of 1700 ° C. or higher and lower than the melting point of the refractory metal. It is characterized by including.

かかる発明によれば、室温から1000℃程度の温度であっても高い機械強度を維持することができ、室温においての靱性値も損なわない加圧焼結体を得ることができる。 According to such an invention, it is possible to obtain a pressure sintered body which can maintain high mechanical strength even at a temperature of about 1000 ° C. from room temperature and does not impair the toughness value at room temperature.

上記した発明において、前記混合工程はボールミルによることを特徴としてもよい。かかる発明によれば、粉体同士を均一に混合できて得られる加圧焼結体の機械強度を均一にし得る。 In the above invention, the mixing step may be characterized by using a ball mill. According to such an invention, the mechanical strength of the pressure sintered body obtained by uniformly mixing the powders can be made uniform.

上記した発明において、前記加圧焼結工程はパルス通電加圧焼結によることを特徴としてもよい。かかる発明によれば、高融点金属からなる粒子を含む粉体同士の焼結を容易とする。 In the above invention, the pressure sintering step may be characterized by pulse energization pressure sintering. According to such an invention, it is easy to sinter powders containing particles made of a refractory metal.

上記した発明において、前記高融点金属は、Mo,W,Ta,Nbのうちの1つ以上からなることを特徴としてもよい。かかる発明によれば、上記した高い機械強度を維持することのできる加圧焼結体を容易に得ることができる。 In the above invention, the refractory metal may be characterized in that it is composed of one or more of Mo, W, Ta, and Nb. According to such an invention, a pressure sintered body capable of maintaining the above-mentioned high mechanical strength can be easily obtained.

本発明の実施例による加圧焼結体の断面組織写真(SEM−COMPO像)である。It is a cross-sectional structure photograph (SEM-COMPO image) of the pressure sintered body according to the Example of this invention. 本発明の実施例による加圧焼結体の製造方法を示すフロー図である。It is a flow chart which shows the manufacturing method of the pressure sintered body by the Example of this invention. 製造試験で製造した加圧焼結体の製造条件を示す一覧表である。It is a list which shows the manufacturing condition of the pressure sintered body manufactured in the manufacturing test. 製造試験で製造した加圧焼結体の断面組織写真(SEM−COMPO像)である。((a)TiC0.5N0.5焼結体、(b) TiC0.5N0.5-20mass% Mo焼結体、(c) TiC0.5N0.5-30mass% Mo焼結体、(d) TiC0.5N0.5-40mass% Mo焼結体、(e) TiC0.5N0.5-50mass% Mo焼結体、(f) TiC0.5N0.5-60mass% Mo焼結体、(g)Mo焼結体)It is a cross-sectional structure photograph (SEM-COMPO image) of the pressure sintered body produced in the production test. ((A) TiC 0.5 N 0.5 sintered body, (b) TiC 0.5 N 0.5 -20mass% Mo sintered body, (c) TiC 0.5 N 0.5 -30mass% Mo sintered body, (d) TiC 0.5 N 0.5- 40mass% Mo sintered body, (e) TiC 0.5 N 0.5 -50mass% Mo sintered body, (f) TiC 0.5 N 0.5 -60mass% Mo sintered body, (g) Mo sintered body) 製造試験で製造した加圧焼結体の断面組織写真(SEM−COMPO像)である。ここで、(a) TiC0.5N0.5-20mass% W焼結体、(b) TiC0.5N0.5-30mass% W焼結体、(c) TiC0.5N0.5-40mass% W焼結体、(d) TiC0.5N0.5-50mass% W焼結体、(e) TiC0.5N0.5-60mass% W焼結体、(g)W焼結体である。It is a cross-sectional structure photograph (SEM-COMPO image) of the pressure sintered body manufactured in the manufacturing test. Here, (a) TiC 0.5 N 0.5 -20mass% W sintered body, (b) TiC 0.5 N 0.5 -30mass% W sintered body, (c) TiC 0.5 N 0.5 -40mass% W sintered body, (d) ) TiC 0.5 N 0.5 -50mass% W sintered body, (e) TiC 0.5 N 0.5 -60mass% W sintered body, (g) W sintered body. 製造試験で製造した加圧焼結体の密度及び相対密度のグラフである。It is a graph of the density and relative density of the pressure sintered body manufactured in the manufacturing test. 製造試験で製造した加圧焼結体の温度と硬さの関係を示すグラフである。It is a graph which shows the relationship between the temperature and hardness of a pressure sintered body manufactured in a manufacturing test. 製造試験で製造した加圧焼結体の温度と硬さの関係を示すグラフである。It is a graph which shows the relationship between the temperature and hardness of a pressure sintered body manufactured in a manufacturing test. 製造試験で製造した加圧焼結体の室温での金属結合相の含有量と硬さとの関係を示すグラフである。It is a graph which shows the relationship between the content of the metal-bonded phase at room temperature, and the hardness of the pressure sintered body produced in the production test. 製造試験で製造した加圧焼結体の600℃での金属結合相の含有量と硬さとの関係を示すグラフである。It is a graph which shows the relationship between the content of the metal-bonded phase at 600 degreeC, and the hardness of the pressure sintered body produced in the production test. 製造試験で製造した加圧焼結体の800℃の金属結合相の含有量と硬さとの関係を示すグラフである。It is a graph which shows the relationship between the content of the metal bonding phase of 800 degreeC, and the hardness of the pressure sintered body produced in the production test. 製造試験で製造した加圧焼結体の1000℃での金属結合相の含有量と硬さとの関係を示すグラフである。It is a graph which shows the relationship between the content of the metal-bonded phase at 1000 degreeC, and the hardness of the pressure sintered body produced in the production test. 製造試験で製造した加圧焼結体の金属結合相の含有量とヤング率及び破壊靭性値との関係を示すグラフである。It is a graph which shows the relationship between the content of the metal bonding phase of the pressure sintered body produced in the production test, Young's modulus and fracture toughness value. 製造試験で製造した加圧焼結体の透過電子顕微鏡写真(TEM−EDS像)である。((a) TiC0.5N0.5-20mass% Mo焼結体、(b) TiC0.5N0.5-50mass% W焼結体)It is a transmission electron micrograph (TEM-EDS image) of the pressure sintered body manufactured in the manufacturing test. ((A) TiC 0.5 N 0.5 -20mass% Mo sintered body, (b) TiC 0.5 N 0.5 -50mass% W sintered body)

以下、本発明の1つの実施例である加圧焼結体について、図1を用いてその詳細を説明する。 Hereinafter, the details of the pressure sintered body, which is one embodiment of the present invention, will be described with reference to FIG.

図1に示すように、加圧焼結体1は、主としてTi(C,N)からなる硬質相粒子2を金属からなる金属結合相3にて結合したもので、室温におけるビッカース硬さをHv1500以上とした加圧焼結体である。ここで、同図は、SEM−EDS(走査型電子顕微鏡(SEM)にエネルギー分散形X線分析装置(EDS)を取り付けたもの)による断面組織の組成像(COMPO像)の写真である。硬質相粒子2は黒く、金属結合相3は白く表示され、断面から深さ約1μまでにおいて両者の重なった部分はその中間色で表示される。本実施例において、Ti(C,N)は、TiC0.50.5を用いた。つまり、加圧焼結体1は、硬質相粒子2であるTiC0.50.5の相と、金属結合相3であるMoの相との二相から構成される。 As shown in FIG. 1, the pressure sintered body 1 is formed by bonding hard phase particles 2 mainly made of Ti (C, N) with a metal bonding phase 3 made of metal, and has a Vickers hardness of Hv1500 at room temperature. This is the pressure sintered body described above. Here, the figure is a photograph of a composition image (COMPO image) of a cross-sectional structure by SEM-EDS (a scanning electron microscope (SEM) equipped with an energy dispersive X-ray analyzer (EDS)). The hard phase particles 2 are displayed in black, the metal bonding phase 3 is displayed in white, and the overlapping portion of the two is displayed in an intermediate color from the cross section to a depth of about 1 μm. In this example, TiC 0.5 N 0.5 was used as Ti (C, N). That is, the pressure sintered body 1 is composed of two phases, a phase of TiC 0.5 N 0.5 which is a hard phase particle 2 and a phase of Mo which is a metal bonding phase 3.

特に、硬質相粒子2の平均粒径は2μm以下であり、金属結合相3は5族又は6族に属する2000℃以上の高融点金属からなる。このような金属として、融点2400℃以上のMo(融点:2623℃),W(融点:3422℃),Ta(融点:3017℃),Nb(融点:2477℃)の4つが挙げられ、これらの混合物も用い得る。本実施例において金属結合相3はMoからなり、40質量%の割合を所定の含有量として加圧焼結体1に含まれる。 In particular, the average particle size of the hard phase particles 2 is 2 μm or less, and the metal bonding phase 3 is made of a refractory metal having a melting point of 2000 ° C. or higher belonging to Group 5 or Group 6. Four such metals include Mo (melting point: 2623 ° C.), W (melting point: 3422 ° C.), Ta (melting point: 3017 ° C.), and Nb (melting point: 2477 ° C.) having a melting point of 2400 ° C. or higher. Mixtures can also be used. In this embodiment, the metal bonding phase 3 is made of Mo and is contained in the pressure sintered body 1 with a predetermined content of 40% by mass.

このような加圧焼結体1によれば、1000℃における高温ビッカース硬さをHv1200以上とすることができる。 According to such a pressure sintered body 1, the high temperature Vickers hardness at 1000 ° C. can be set to Hv1200 or more.

また、室温において、ヤング率を400GPa以上とでき、破壊靱性値を4MPa・m1/2以上とすることができる。 Further, at room temperature, Young's modulus can be 400 GPa or more, and fracture toughness value can be 4 MPa · m 1/2 or more.

このような、加圧焼結体1は、そのうちの金属結合相3を構成する金属の所定の含有量として好ましい範囲があり、質量%で、以下の通りである。Moを単独で含む場合、10〜50%の割合とすることが好ましい。また、Wを単独で含む場合、10〜60%の割合とすることが好ましい。また、Taを単独で含む場合、10〜60%の割合とすることが好ましい。また、Nbを単独で含む場合、10〜50%の割合とすることが好ましい。 Such a pressure sintered body 1 has a preferable range as a predetermined content of the metal constituting the metal bonding phase 3 among them, and is as follows in mass%. When Mo is contained alone, the ratio is preferably 10 to 50%. When W is contained alone, the ratio is preferably 10 to 60%. When Ta is contained alone, the ratio is preferably 10 to 60%. When Nb is contained alone, the ratio is preferably 10 to 50%.

次に、加圧焼結体1の製造方法について、図2を用いて説明する。 Next, a method for producing the pressure sintered body 1 will be described with reference to FIG.

図2に示すように、まず、粉体を混合する(混合工程:S1)。ここで混合する粉体は、硬質相粒子2を構成する平均粒径2μm以下のTi(C,N)の粒子からなる粉体と、金属結合相3を構成する金属の平均粒径2μm以下の粒子からなる粉体である。これらを上記したような所定の含有量となるように配合し、粉体同士を均一に分散させるように混合する。例えば、ボールミルを用いると、容易に粉体同士を均一に分散させ得て好ましい。特に、粉体を均一に分散させることで、硬質相粒子2と金属結合相3との接触面積を大きくして、金属結合相3による硬さの低い部分的な塊を生成させないようにする。なお、混合工程における溶媒やその他の有機物を粉体から取り除くために熱処理等をしてもよい。 As shown in FIG. 2, first, the powder is mixed (mixing step: S1). The powder to be mixed here is a powder composed of Ti (C, N) particles having an average particle size of 2 μm or less constituting the hard phase particles 2 and a metal having an average particle size of 2 μm or less forming the metal bonding phase 3. It is a powder composed of particles. These are blended so as to have a predetermined content as described above, and the powders are mixed so as to be uniformly dispersed. For example, it is preferable to use a ball mill because the powders can be easily and uniformly dispersed. In particular, by uniformly dispersing the powder, the contact area between the hard phase particles 2 and the metal bonding phase 3 is increased so that partial lumps having low hardness are not generated by the metal bonding phase 3. In addition, heat treatment or the like may be performed in order to remove the solvent and other organic substances in the mixing step from the powder.

次いで、混合した粉体を加圧して焼結させる(加圧焼結工程:S2)。ここでは、例えばパルス通電加圧焼結を行うと、高融点金属からなる粒子を含む粉体同士の焼結を容易とし得て好適である。また、焼結温度は1700℃以上、且つ、高融点金属の融点以下の温度とする。焼結時間は例えば5〜30分とし得て、加圧する圧力としては例えば40MPaとし得る。 Next, the mixed powder is pressurized and sintered (pressure sintering step: S2). Here, for example, pulse energization pressure sintering is preferable because it can facilitate sintering of powders containing particles made of refractory metal. The sintering temperature is 1700 ° C. or higher and lower than the melting point of the refractory metal. The sintering time can be, for example, 5 to 30 minutes, and the pressurizing pressure can be, for example, 40 MPa.

以上のような方法で、加圧焼結体1を得ることができる。 The pressure sintered body 1 can be obtained by the above method.

[製造試験]
次に、複数種類の加圧焼結体を製造して、硬さ等を調査する製造試験を行った結果について説明する。
[Manufacturing test]
Next, the results of manufacturing tests for manufacturing a plurality of types of pressure sintered bodies and investigating hardness and the like will be described.

まず、図3に示す各組成となるよう配合された粉体はボールミルで混合された。ボールミルにおいては、プラスチックコーティングされた鋼球をメディアに用いてヘキサンを加えた湿式混合とし、混合時間を72時間とした。混合後は、70〜80℃に加熱して粉体を乾燥させ、さらにメディアのプラスチック分を除去するために真空雰囲気中で900℃に加熱して2時間保持した。 First, the powders blended to have the respective compositions shown in FIG. 3 were mixed by a ball mill. In the ball mill, a plastic-coated steel ball was used as a medium for wet mixing with hexane added, and the mixing time was 72 hours. After mixing, the powder was heated to 70 to 80 ° C. to dry the powder, and further heated to 900 ° C. in a vacuum atmosphere to remove the plastic component of the media and held for 2 hours.

なお、混合に用いた粉体は、粒径0.70〜1.0μmで純度98.9%以上のTiC0.50.5粉体、粒径0.50〜0.99μmで純度99.8%以上のMo粉体、粒径約0.6μmで純度99.9%のW粉体である。図示したように、TiC0.50.5−Mo粉体は、Moの含有量を、質量%で、20%、30%、40%、50%、60%とする5種類とした。また、TiC0.50.5−W粉体は、Wの含有量を、質量%で、20%、30%、40%、50%、60%、70%、80%とする7種類とした。 The powders used for mixing were TiC 0.5 N 0.5 powder having a particle size of 0.70 to 1.0 μm and a purity of 98.9% or more, and a purity of 99 with a particle size of 0.50 to 0.99 μm. Mo powder of 8.8% or more, W powder having a particle size of about 0.6 μm and a purity of 99.9%. As shown in the figure, the TiC 0.5 N 0.5- Mo powder has five types of Mo content, which are 20%, 30%, 40%, 50%, and 60% by mass. In addition, there are seven types of TiC 0.5 N 0.5- W powder having a W content of 20%, 30%, 40%, 50%, 60%, 70%, and 80% in terms of mass%. And said.

続いて、混合された各組成の粉体は、それぞれパルス通電加圧焼結によって焼結された。焼結における加圧力と焼結時間は同図に示す通りである。 Subsequently, the mixed powders of each composition were sintered by pulse energization pressure sintering. The pressing force and sintering time in sintering are as shown in the figure.

得られた加圧焼結体は、SEM−EDSによる断面観察、超音波パルスエコー法によるヤング率測定、IF法による室温での破壊靭性値測定にそれぞれ供された。さらに、1気圧のアルゴンガス雰囲気中での室温〜1000℃におけるマイクロビッカース硬さ試験に供された。マイクロビッカース硬さ試験においては、荷重を9.8Nとし、保持時間を10秒とした。また、アルキメデス法による密度測定に供されるとともに、得られた密度からTiC0.50.5、Mo、Wの理論密度を用いて相対密度も算出された。 The obtained pressurized sintered body was subjected to cross-sectional observation by SEM-EDS, Young's modulus measurement by ultrasonic pulse echo method, and fracture toughness value measurement at room temperature by IF method, respectively. Further, it was subjected to a Micro Vickers hardness test at room temperature to 1000 ° C. in an argon gas atmosphere of 1 atm. In the Micro Vickers hardness test, the load was 9.8 N and the holding time was 10 seconds. In addition, the density was measured by the Archimedes method, and the relative density was also calculated from the obtained density using the theoretical densities of TiC 0.5 N 0.5 , Mo, and W.

図4に示すように、TiC0.50.5、TiC0.50.5−Mo及びMoの加圧焼結体の断面のSEM−EDS写真を得た。すなわち、Moの含有量を0〜100質量%まで変えたTiC0.50.5−Moの加圧焼結体の断面写真である。その含有量は、質量%で、(a)0%、(b)20%、(c)30%、(d)40%、(e)50%、(f)60%、(g)100%である。これらの加圧焼結体は、(a)及び(g)を除いて、TiC0.50.5相とMo相の二相から構成されることが判る。なお、図1は(d)の拡大写真である。 As shown in FIG. 4, SEM-EDS photographs of cross sections of TiC 0.5 N 0.5 , TiC 0.5 N 0.5- Mo and Mo pressure sintered bodies were obtained. That is, it is a cross-sectional photograph of a pressure sintered body of TiC 0.5 N 0.5 −Mo in which the Mo content is changed from 0 to 100% by mass. The content is (a) 0%, (b) 20%, (c) 30%, (d) 40%, (e) 50%, (f) 60%, (g) 100% in mass%. Is. It can be seen that these pressure sintered bodies are composed of two phases, a TiC 0.5 N 0.5 phase and a Mo phase, except for (a) and (g). Note that FIG. 1 is an enlarged photograph of (d).

図5に示すように、TiC0.50.5−Wの加圧焼結体の断面のSEM−EDS写真を得た。Wの含有量は、同様に質量%で、(a)20%、(b)30%、(c)40%、(d)50%、(e)60%、(f)100%である。これらの加圧焼結体は、同様に、(f)を除いて、TiC0.50.5相とW相の二相から構成されることが判る。 As shown in FIG. 5, SEM-EDS photographs of cross sections of a pressure sintered body of TiC 0.5 N 0.5- W were obtained. Similarly, the content of W is (a) 20%, (b) 30%, (c) 40%, (d) 50%, (e) 60%, and (f) 100% in mass%. Similarly, it can be seen that these pressure sintered bodies are composed of two phases, a TiC 0.5 N 0.5 phase and a W phase, except for (f).

図6を参照すると、Wの加圧焼結体を除いて、他の全ての加圧焼結体の相対密度が100%に近い値を示した。つまり、TiC0.50.5−Moの加圧焼結体及びTiC0.50.5−Wの加圧焼結体はともに相対密度が高い。 With reference to FIG. 6, the relative densities of all the other pressure-sintered bodies except the W pressure-sintered body showed values close to 100%. That is, both the pressure sintered body of TiC 0.5 N 0.5- Mo and the pressure sintered body of TiC 0.5 N 0.5- W have high relative densities.

図7に示すように、マイクロビッカース硬さ試験の結果、Moの含有量を20〜40%としたTiC0.50.5−Mo加圧焼結体は、室温から1000℃までのいずれの温度においてもTiC0.50.5のみの加圧焼結体に比べて約Hv500以上の高い硬さを有していた。なお、TiC0.50.5−Mo加圧焼結体は、いずれについても室温でHv1500以上であり、1000℃でHv1200以上であった。なお、比較のため、超硬合金(三菱マテリアル株式会社製、HTi10)の硬さも併せて示した。 As shown in FIG. 7, as a result of the Micro Vickers hardness test, the TiC 0.5 N 0.5- Mo pressure sintered body having a Mo content of 20 to 40% was obtained from room temperature to 1000 ° C. Even at this temperature, it had a hardness of about Hv500 or more higher than that of the pressure sintered body containing only TiC 0.5 N 0.5 . The TiC 0.5 N 0.5- Mo pressure sintered body had Hv1500 or higher at room temperature and Hv1200 or higher at 1000 ° C. For comparison, the hardness of cemented carbide (HTi10 manufactured by Mitsubishi Materials Corporation) is also shown.

図8に示すように、マイクロビッカース硬さ試験の結果、Wの含有量を20〜70%としたTiC0.50.5−W加圧焼結体は、室温から1000℃までのいずれの温度においてもTiC0.50.5のみの加圧焼結体に比べて高い硬さを有していた。この硬さの差は、最大でHv1000程度であった。なお、TiC0.50.5−W加圧焼結体は、いずれについても室温でHv1500以上であり、1000℃でHv1200以上であった。 As shown in FIG. 8, as a result of the Micro Vickers hardness test, the TiC 0.5 N 0.5- W pressure sintered body having a W content of 20 to 70% was obtained from room temperature to 1000 ° C. Even at this temperature, it had a higher hardness than the pressure sintered body containing only TiC 0.5 N 0.5 . This difference in hardness was about Hv1000 at the maximum. The TiC 0.5 N 0.5 −W pressure sintered body had Hv1500 or higher at room temperature and Hv1200 or higher at 1000 ° C.

図9〜図12は、それぞれ、室温、600℃、800℃、1000℃でのマイクロビッカース硬さ試験の結果を示した。これらは、上記したマイクロビッカース試験の結果を温度毎にまとめて、金属結合相(Mo、W)の含有量で整理したものである。上記したようにMoの含有量を20〜40%としたTiC0.50.5−Mo加圧焼結体、及び、Wの含有量を20〜70%としたTiC0.50.5−W加圧焼結体は、いずれの温度でもTiC0.50.5のみの加圧焼結体に比べて高い硬さを有していた。 9 to 12 show the results of the Micro Vickers hardness test at room temperature, 600 ° C., 800 ° C., and 1000 ° C., respectively. These are the results of the above-mentioned Micro Vickers test summarized by temperature and arranged by the content of the metal bonding phase (Mo, W). As described above, a TiC 0.5 N 0.5- Mo pressure sintered body having a Mo content of 20 to 40% and a TiC 0.5 N 0 having a W content of 20 to 70%. The .5- W pressure sintered body had a higher hardness than the pressure sintered body containing only TiC 0.5 N 0.5 at any temperature.

図13には、TiC0.50.5−Mo加圧焼結体、及び、TiC0.50.5−W加圧焼結体のヤング率及び破壊靭性値を示した。ヤング率は、Moの含有量を20〜60質量%とした場合、Wの含有量を20〜80質量%とした場合の全てで400GPa以上であった。また、TiC0.50.5に対してMo又はWの金属結合相を加えることで破壊靭性値を向上させ得ることが判った。特に、Wの含有量を40〜60質量%とした場合と、Wの含有量を60〜80質量%とした場合には破壊靭性値を5MPa・m1/2以上とすることができた。 FIG. 13 shows the Young's ratio and fracture toughness values of the TiC 0.5 N 0.5- Mo pressure sintered body and the TiC 0.5 N 0.5- W pressure sintered body. The Young's modulus was 400 GPa or more in all cases where the Mo content was 20 to 60% by mass and the W content was 20 to 80% by mass. It was also found that the fracture toughness value can be improved by adding a metal bonding phase of Mo or W to TiC 0.5 N 0.5 . In particular, when the W content was 40 to 60% by mass and when the W content was 60 to 80% by mass, the fracture toughness value could be 5 MPa · m 1/2 or more.

これらの結果を踏まえ、TiC0.50.5−Mo加圧焼結体において、Moの含有量は10〜50質量%の割合とすることが好ましい。また、TiC0.50.5−W加圧焼結体において、Wの含有量は10〜60質量%の割合とすることが好ましい。 Based on these results, the Mo content is preferably 10 to 50% by mass in the TiC 0.5 N 0.5- Mo pressure sintered body. Further, in the TiC 0.5 N 0.5 −W pressure sintered body, the W content is preferably 10 to 60% by mass.

なお、Moの粉体の粒径を大きくした場合には、高温において十分な硬さを得られないことも別途確認した。 It was also separately confirmed that when the particle size of the Mo powder was increased, sufficient hardness could not be obtained at high temperatures.

図14には、上記した製造方法で製造されたTiC0.50.5−Mo及びTiC0.50.5−Wの各加圧焼結体について、透過電子顕微鏡にて観察したTEM−EDS写真を示した。ここでは、前者ではMoを20質量%、後者ではWを50質量%加えた各加圧焼結体の例を示した。(a)では、粒子状でコントラストを明るく(白く)観察されるMo相、粒子状でコントラストを暗く(黒く)観察されるTi(C,N)相とともに、その間に、網目状にコントラストを中間値(灰色)とするMo−richのTi(C,N)相が観察される。同様に、(b)では、粒子状でコントラストを明るく(白く)観察されるW相、粒子状でコントラストを暗く観察されるTi(C,N)相とともに、その間に、網目状にコントラストを中間値(灰色)とするW−richのTi(C,N)相が観察される。つまり、焼結体を構成する粒子間に、それぞれ、Mo−rich相及びW−rich相が非常に薄く且つ粒子界に沿ってきれいに入り込んでこの粒子間を結合していることが判る。かかる粒子間の結合組織がサーメットの高強度化に貢献していると推測された。 In FIG. 14, each pressure sintered body of TiC 0.5 N 0.5- Mo and TiC 0.5 N 0.5- W produced by the above-mentioned production method was observed with a transmission electron microscope. TEM-EDS photographs are shown. Here, an example of each pressure sintered body in which 20% by mass of Mo is added in the former and 50% by mass of W is added in the latter is shown. In (a), the Mo phase in which the contrast is observed to be bright (white) in the form of particles and the Ti (C, N) phase in which the contrast is observed to be dark (black) in the form of particles are observed, and the contrast is intermediate in a mesh pattern between them. The Ti (C, N) phase of Mo-rich as the value (gray) is observed. Similarly, in (b), the W phase in which the contrast is observed to be bright (white) in the form of particles and the Ti (C, N) phase in which the contrast is observed to be dark in the form of particles are observed, and the contrast is intermediate in a mesh pattern between them. The Ti (C, N) phase of W-rich as the value (gray) is observed. That is, it can be seen that the Mo-rich phase and the W-rich phase are very thin and penetrate cleanly along the particle boundary between the particles constituting the sintered body, respectively, and bond the particles. It was speculated that the connective tissue between the particles contributed to increasing the strength of the cermet.

以上、本発明による実施例及びこれに基づく変形例を説明したが、本発明は必ずしもこれに限定されるものではなく、当業者であれば、本発明の主旨又は添付した特許請求の範囲を逸脱することなく、様々な代替実施例及び改変例を見出すことができるであろう。 Although the examples according to the present invention and the modifications based on the present invention have been described above, the present invention is not necessarily limited to this, and those skilled in the art deviate from the gist of the present invention or the appended claims. Without doing so, various alternative and modified examples could be found.

1 加圧焼結体
2 硬質相粒子
3 金属結合相
1 Pressurized sintered body 2 Hard phase particles 3 Metal bonding phase

Claims (11)

主としてTi(C,N)からなる硬質相粒子を金属からなる金属結合相にて結合し室温におけるビッカース硬さをHv1500以上とした加圧焼結体であって、
前記硬質相粒子の平均粒径を2μm以下とするとともに、5族又は6族に属する2400℃以上の高融点金属からなる前記金属結合相を質量%で10〜70%の割合で含み、1000℃における高温ビッカース硬さをHv1200以上としたことを特徴とする加圧焼結体。
A pressure sintered body in which hard phase particles mainly composed of Ti (C, N) are bonded by a metal bonding phase composed of a metal and the Vickers hardness at room temperature is Hv1500 or higher.
The average particle size of the hard phase particles is 2 μm or less, and the metal bonding phase composed of a refractory metal of 2400 ° C. or higher belonging to Group 5 or Group 6 is contained in a mass% of 10 to 70% at 1000 ° C. A pressure sintered body characterized in that the high-temperature Vickers hardness in
室温でのヤング率を400GPa以上としたことを特徴とする請求項1記載の加圧焼結体。 The pressure sintered body according to claim 1, wherein the Young's modulus at room temperature is 400 GPa or more. 室温での破壊靱性値を4MPa・m1/2以上としたことを特徴とする請求項2記載の加圧焼結体。 The pressure sintered body according to claim 2, wherein the fracture toughness value at room temperature is 4 MPa · m 1/2 or more. 質量%でMoを10〜50%の割合で含むことを特徴とする請求項1乃至3のうちの1つに記載の加圧焼結体。 The pressure sintered body according to any one of claims 1 to 3, wherein Mo is contained in a proportion of 10 to 50% by mass. 質量%でWを10〜60%の割合で含むことを特徴とする請求項1乃至3のうちの1つに記載の加圧焼結体。 The pressure sintered body according to any one of claims 1 to 3, wherein W is contained in a proportion of 10 to 60% by mass. 質量%でTaを10〜60%の割合で含むことを特徴とする請求項1乃至3のうちの1つに記載の加圧焼結体。 The pressure sintered body according to any one of claims 1 to 3, wherein Ta is contained in a proportion of 10 to 60% by mass. 質量%でNbを10〜50%の割合で含むことを特徴とする請求項1乃至3のうちの1つに記載の加圧焼結体。 The pressure sintered body according to any one of claims 1 to 3, wherein Nb is contained in a proportion of 10 to 50% by mass. 主としてTi(C,N)からなる硬質相粒子を金属からなる金属結合相にて結合し室温及び1000℃におけるビッカース硬さをそれぞれHv1500以上及びHv1200以上とする加圧焼結体の製造方法であって、
2μm以下の平均粒径のTi(C,N)からなる粒子に対して、2μm以下の平均粒径の5族又は6族に属する2400℃以上の高融点金属からなる粒子を質量%で10〜70%の割合で混合する混合工程と、1700℃以上且つ前記高融点金属の融点以下の温度で加圧する加圧焼結工程と、を含むことを特徴とする加圧焼結体の製造方法。
This is a method for producing a pressure sintered body in which hard phase particles mainly composed of Ti (C, N) are bonded by a metal bonding phase composed of a metal to have Vickers hardnesses of Hv1500 or higher and Hv1200 or higher, respectively, at room temperature and 1000 ° C. hand,
Particles made of refractory metal of 2400 ° C. or higher belonging to Group 5 or Group 6 having an average particle size of 2 μm or less are 10 by mass% of particles made of Ti (C, N) having an average particle size of 2 μm or less. A method for producing a pressure sintered body, which comprises a mixing step of mixing at a ratio of 70% and a pressure sintering step of pressurizing at a temperature of 1700 ° C. or higher and lower than the melting point of the refractory metal.
前記混合工程はボールミルによることを特徴とする請求項8記載の加圧焼結体の製造方法。 The method for producing a pressure sintered body according to claim 8, wherein the mixing step is performed by a ball mill. 前記加圧焼結工程はパルス通電加圧焼結によることを特徴とする請求項8又は9に記載の加圧焼結体の製造方法。 The method for producing a pressure sintered body according to claim 8 or 9, wherein the pressure sintering step is performed by pulse energization pressure sintering. 前記高融点金属は、Mo,W,Ta,Nbのうちの1つ以上からなることを特徴とする請求項8乃至10のうちの1つに記載の加圧焼結体の製造方法。

The method for producing a pressure sintered body according to any one of claims 8 to 10, wherein the refractory metal comprises one or more of Mo, W, Ta, and Nb.

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