JP4351470B2 - Hard composite sintered body, hard composite structure, and manufacturing method - Google Patents

Description

【００４３】
次に、上記マルチフィラメントタイプの集束繊維成形体を５０ｍｍの長さにカットし、並列に整列させてシート状とし、このシート６枚を隣接するシート内の硬質複合繊維焼結体同士が４５°の角度となるように積層して直方体形状の積層成形体を作製した。
【００４４】
その後、前記積層体に対して３００〜７００℃まで１００時間で昇温することによって脱バインダ処理を行った後、黒鉛型に装填し、１．３Ｐａ（０．０１Ｔｏｒｒ）以下の真空中で加圧力２０ＭＰａの加圧条件下で、直流電流を流して焼結した。昇温速度は１００℃／分で１３５０℃まで昇温し、その温度で３分間保持した後、５０℃／分の速度で冷却した。このようにして得られた焼結体は、割れもなく良好な外観を呈していた。これら焼結体の黒皮（表面変質部）を除去後、アルキメデス法で比重を測定したところ、試料Ｎｏ．１〜５のいずれの焼結体も緻密で９８％以上の理論密度を有していた。なお、試料Ｎｏ．６〜９の密度は９５％程度であった。
【００４５】
得られた硬質複合焼結体から３×４×１２ｍｍのサンプルを切り出し、軸中心に２０ｍ／ｍｉｎで回転している直径が２０ｍｍの円盤状状ＳｉＣ砥石に、硬質複合焼結体３×４ｍｍの面を２０Ｎの圧力で１０分間押しつけた時の摩耗量を測定する耐摩試験を行った。評価方法としては、標準試料としてＮｏ．１０のサンプルの摩耗量を１００とした時のＮｏ．１〜９の焼結体の摩耗量を比摩耗量として算出し、耐摩耗性として表記した。
【００４６】
次にこの研磨面を鏡面仕上げし、走査型電子顕微鏡（ＳＥＭ）で観察して硬質複合焼結体中のダイヤモンド粒子の外周表面に包含層が存在するか、および包含層の包含率・平均厚みを画像解析法にて測定するとともに、ＩＳＯ４５０５に準じて遊離炭素の含有量を特定した。なお、本発明においては、焼結体断面についての１０００倍の走査型電子顕微鏡写真にて遊離炭素の析出が認められなかった試料については遊離炭素の評価をＣ００として判定した。また、包含相が存在する試料についてはその近傍について波長分散型Ｘ線マイクロアナリシスの線分析を行い、包含層領域付近の組成傾斜の有無を測定した。なお、各試料について芯材の平均直径Ｄ_１と表皮材の厚みＤ_２との比（Ｄ_２／Ｄ_１）は０．１であった。さらにＪＩＳＲ１６０７に準じたＩＦ法により破壊靭性値を測定した。
【００４７】
また、上記サンプルを３ｍｍ×４ｍｍ×スパン１０ｍｍの長さに加工してＪＩＳＲ１６０１に準じた三点曲げ抗折力試験を行った。これら結果を表２に示す。
【００４８】
【表２】

【００４９】
表２の結果に示すように、本発明に従い、周期律表４ａ、５ａ、６ａ族金属を外周表面に被覆したダイヤモンド粒子を原料とし、硬質焼結体内部にダイヤモンド粒子を含有するとともに、遊離炭素がＣ０２以下である試料Ｎｏ．１〜５については、耐摩耗性、破壊靭性および強度共に優れていることが確認できた。
【００５０】
本発明を用いた試料は分散ダイヤモンド粒子がＢ１型固溶体相で包含されている構造であり、その為、硬質焼結体マトリックスとの結合強度が高まり、破壊靭性および強度を維持したまま耐摩耗性を著しく向上することができた。特に、包含相が傾斜組成を取る試料Ｎｏ．１、２、４、５はさらに優れた結合力を得ることができ、耐摩耗性が向上している。
【００５１】
これに対して、何も被覆しないか、または周期律表４ａ、５ａ、６ａ族金属以外の化合物を外周表面に被覆したダイヤモンド粉末を原料として用いた試料Ｎｏ．６〜９については、硬質焼結体中に分散するダイヤモンド粒子の外周にグラファイト相が析出しており、破壊靭性および強度が低いものであった。さらに試料Ｎｏ．８および９については特にグラファイト相が多く摩耗試験の際、ダイヤモンド粒子が脱落し、標準試料である芯材中にダイヤモンド粒子を含有しない超硬合金の試料Ｎｏ．１０よりも劣る結果となった。
【００５２】
【発明の効果】
以上詳述したとおり、本発明の硬質複合焼結体によれば、多量の有機バインダを用いて作製する複合焼結体の芯材として硬質合金原料粉末中に、周期律表４ａ、５ａ、６ａ族金属の群より選ばれる少なくとも一種の金属を被覆したダイヤモンド粒子を添加、混合することにより、焼成中にダイヤモンド粒子が分解してグラファイト化することを抑制して、芯材をダイヤモンド粒子５〜５０体積％含有し、かつ遊離炭素がＣ０２以下である焼結体とすることができ、優れた耐摩耗性を有し、かつ超硬合金と同等の強度・靭性を有する硬質複合焼結体が得られる。
【図面の簡単な説明】
【図１】本発明の硬質複合焼結体の一例を示す、（ａ）概略断面図、（ｂ）（ａ）のＰ部拡大図である。
【図２】本発明の硬質複合焼結体の製造工程を示す概略図である。
【図３】本発明の硬質複合焼結体の配置例を示す概略図である。
【符号の説明】
１ 硬質複合焼結体
２ 第１硬質相
３ ダイヤモンド粒子
４ 第２硬質相
５ 結合相
７ 芯材
８ 表皮材
１１ 成形体
１２ 芯材用成形体
１３ 表皮部材用成形体
１４ 押出成形機
１５ 複合成形体
１６ マルチフィラメント構造の複合成形体
１７ シート成形体
１８ 積層成形体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hard composite sintered body and a composite structure composed of a long core material and a skin material covering the outer periphery thereof, and a method for producing the same.
[0002]
[Prior art]
In recent years, a technique for improving toughness in addition to hardness and strength of a structure has been studied by coating the outer periphery of a long core material such as a fiber with another member. For example, in Patent Document 1, Hard composite firing with a high toughness sintered body having a composition different from the core material coated on the outer periphery of a core material made of a high hardness sintered body such as a cermet (for example, WC-Co), a diamond sintered body, or a cBN sintered body It is described that by producing a composite structure including a knot, the fracture resistance of the structure can be increased and the toughness can be increased without reducing the hardness.
[0003]
On the other hand, in Patent Documents 2 and 3, by adding diamond particles coated with TiN or the like to the surface of the cemented carbide, the decomposition of the diamond particles that thermally decompose during firing is suppressed, and the diamond particles fall off. It is described that a homogeneously dispersed sintered body can be obtained without this.
[0004]
[Patent Document 1]
US Pat. No. 6,063,502 gazette
[Patent Document 2]
JP-A-9-194978 [0006]
[Patent Document 3]
Japanese Patent Laid-Open No. 12-54056
[Problems to be solved by the invention]
However, in a composite structure such as Patent Document 1, when a cemented carbide in which diamond particles having excellent hardness and toughness are dispersed is used as a core material, a large amount of an organic binder is added when producing the composite structure. Because of the coextrusion molding, diamond particles may be decomposed by the firing atmosphere and deposited as carbon, or large voids may be generated, and there are inhomogeneous parts that can become structural defects in the structure of the hard composite sintered body. There is a problem that the strength is reduced and the portion where a large amount of organic binder is decomposed and volatilized becomes a void during firing, and the void disappears during firing to make the structure dense. As a result of the large firing shrinkage, large residual stress is generated between the core material and the skin member in the hard composite sintered body after firing, or in some cases, peeling occurs between the two. Flip easier, the strength of the hard composite sintered body there is a problem that decreases.
[0008]
Further, as in Patent Documents 2 and 3, when a hard composite sintered body is produced by adding diamond particles coated with TiN as a raw material, a carbon excess atmosphere that decomposes and volatilizes a large amount of the organic binder in the composite structural member. Among them, it is difficult to suppress the decomposition of diamond particles generated during firing, and there has been a problem that diamond particles are precipitated in a large amount as decomposed graphite in the sintered body.
[0009]
The present invention has been made to solve the above-mentioned problems, and its purpose is to use a sintered body in which diamond particles are dispersed in a hard alloy as a core material in a hard composite sintered body produced using a large amount of an organic binder. Even in this case, it is an object to provide a hard composite sintered body excellent in strength and toughness as well as wear resistance by suppressing the decomposition and graphitization of diamond particles during firing.
[0010]
[Means for Solving the Problems]
As a result of studying the above problems, the present inventors have found that in the hard alloy raw material powder as a core material of a hard composite sintered body produced using a large amount of organic binder, periodic table 4a, 5a, 6a group metals By adding and mixing diamond particles coated with at least one metal selected from the group, diamond particles can be decomposed and graphitized even in a high carbon atmosphere where a large amount of organic binder components are volatilized during firing. The core material can be contained in 5-50% by volume of diamond particles and free carbon can be made C02 or less, has excellent wear resistance, and has the same strength and toughness as cemented carbide. It was found that a hard composite sintered body having the same can be obtained.
[0011]
That is, the hard sintered body of the present invention includes 50 to 95% by volume of a first hard phase made of any of tungsten carbide, titanium nitride, or titanium carbonitride, 5% by volume to less than 50% by volume of diamond particles, Bonds composed of iron group metals and at least one second hard phase selected from the group consisting of carbides, nitrides, and carbonitrides of periodic table 4a, 5a, 6a metals other than one hard phase The hard surface is bonded with a phase , 60% or more of the outer peripheral surface of the diamond particles is covered by the second hard phase, and the amount of free carbon defined by the porosity of the ISO 4505 alloy is C02 or less. the outer peripheral surface of the elongated core member made of a sintered body, from multifilament structures plurality of converging composite fiber formed by coating the skin material consisting of hard sintered bodies having a composition different from the core material It is characterized in that that.
[0012]
Here, when the outer peripheral surface of 60% or more of the diamond particles is included in the second hard phase, the adhesion between the diamond particles and the hard sintered body matrix is strengthened, and the diamond particles are prevented from falling off. There is.
[0013]
In addition, since the concentration of the second hard phase including the diamond particles gradually decreases from the outer peripheral surface of the diamond particles toward the binding phase, the bonding force of the diamond particles to the hard sintered body is further increased. Dropping off of diamond particles can be further suppressed.
[0014]
Note that the hard composite structure including the hard composite sintered body has excellent hardness, strength, and toughness, and is applied as a structural member such as an excavation tool, a cutting tool, a wear-resistant member, a sliding member, and a heat-resistant member. Is possible.
[0015]
Furthermore, the manufacturing method of the composite hard sintered body of the present invention includes (a) at least one powder selected from the group of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals in the periodic table, and iron. A core material formed by forming a mixture of group metal powder, diamond particles coated with at least one metal selected from the group of metals in the periodic table 4a, 5a, and 6a and an organic binder into a long shape And (b) forming a molded body for skin material having a composition different from that of the molded body in the step (a) to cover the outer periphery of the molded body for core material in the step (a). to prepare placed composite molded body, and firing the step of preparing a converging composite fiber of multifilament structures plurality of converging the plurality synthesis form, the (c) (c) above the converging composite fiber material, carbonized Of tungsten, titanium nitride or titanium carbonitride 50% to 95% by volume of the first hard phase, 5% by volume to less than 50% by volume of the diamond particles, and carbides, nitrides, and metals of the periodic tables 4a, 5a, and 6a other than the first hard phase, At least one second hard phase of 0 to 15% by volume selected from the group consisting of carbonitrides is bonded with a binder phase made of an iron group metal, and 60% or more of the outer peripheral surface of the diamond particles is the second hard phase. The outer peripheral surface of a long core material composed of a hard sintered body that is included in the phase and has a free carbon amount defined by the porosity of an ISO 4505 alloy that is C02 or less is different from the core material. And a step of producing a hard composite sintered body characterized by comprising a multifilament structure in which a plurality of composite fibers formed by coating a skin material made of a hard sintered body having a composition are converged. thing There, in the process, it is possible to firmly dispersed maintain the diamond particles in the sintered body by carbonizing during firing the metal coating the diamond particles (c) step. At this time, the diamond raw material powder is coated, and if necessary, the 4a, 5a and 6a metals forming the second hard phase are diffused into the diamond particles by the bonding metal in the hard composite sintered body so that the diamond particles become graphite. In addition, the diamond particles in the sintered body are maintained in a healthy state by maintaining the carbon particles in which the diamond particles are graphitized during firing by the above-mentioned metal reacting and consuming them to form carbides. It is possible to increase the content ratio of carbon and to suppress the precipitation of residual carbon that causes a decrease in strength in the sintered body.
[0016]
In order to firmly bond the diamond particles in the composite sintered body without graphitization and without dropping from the hard sintering, the metal particles coated on the outer peripheral surface of the diamond particles in the raw material are used. The coating thickness is desirably 0.1 to 3 μm.
[0017]
Further, in the step (c), the metal covering the diamond raw material powder is carbonized during firing, and a void in which a large amount of organic binder is decomposed and volatilized during firing is eliminated by volume expansion due to carbonization of the metal. This is desirable in that the sintered body is densified to suppress the generation of large residual stress between the core material and the skin member of the sintered body and the reduction in strength due to peeling.
[0018]
Furthermore, it is desirable to add the organic binder in the step (a) at a ratio of 30 to 70% by volume with respect to the entire mixture in terms of producing a composite molded body and a hard composite sintered body having a homogeneous structure. .
[0019]
Further, in the step (a), the periodic table 4a, 5a, 6a group metal powder is further added at a ratio of 1 to 20% by mass, and in the step (c), the diamond powder is decomposed during firing. By firing so that the decomposed components generated in the reaction and the metal powder react to carbonize and expand in volume, a thermally stable compressive residual stress is generated in the hard sintered body, and the hard composite sintered body becomes tough. In addition, the dispersed diamond particles are less likely to fall off, the brazing and welding work are simplified, and the application field of this material can be expanded.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The hard composite sintered body of the present invention will be described on the basis of the schematic sectional view of FIG. 1 as an example and an enlarged view of a part thereof.
[0021]
According to FIG. 1, the hard composite sintered body 1 includes a first hard phase 2:50 to 95% by volume and a diamond particle 3: 5 to 50% by volume made of tungsten carbide, titanium nitride, or titanium carbonitride. And at least one second hard phase 4: 0 to 15% by volume selected from the group consisting of carbides, nitrides, and carbonitrides of periodic table 4a, 5a, 6a metal other than the first hard phase 2; Of the long core material 7 made of a hard sintered body in which the amount of free carbon defined by the porosity of the ISO 4505 alloy is C02 or less. Is coated with a hard sintered body (skin material 8) having a composition different from that of the core material 7.
[0022]
As a result, the diamond particles 3 in the hard sintered body of the core material 7 are dispersed without falling off, and the wear resistance of the hard composite sintered body 1 is remarkably improved.
[0023]
That is, if the content of the diamond particles 3 is 5% by volume or more and less than 50% by volume , if the content is less than 5% by volume, the effect of improving the characteristics due to the inclusion of the diamond particles 3 hardly appears, and the hardness decreases. This is because when the content of 3 is 50% by volume or more, it is difficult to densify the core material 7 and the strength is significantly reduced. A particularly preferable range of the content of the diamond particles 3 is 10 to 40% by volume, particularly 10 to 35% by volume. According to the present invention, the diamond particles 3 described above can also be dispersed in the skin material 8 of the hard composite sintered body 1.
[0024]
Further, according to the present invention, 60% or more of the outer peripheral surface of the diamond particle 3 is covered by the second hard phase 4 as shown in the enlarged view of the P portion of FIG. 1A shown in FIG. As a result, the diamond particles 3 are firmly adhered to the sintered body 1 and the diamond particles 3 are prevented from falling off. Although it is desirable that the outer peripheral surface of the diamond particle 3 is entirely included in the second hard phase 4, according to the present invention, 60% or more of the outer peripheral surface, in particular 80 As long as a portion of at least% is included, the bonding force of the diamond particles 3 can be sufficiently increased.
[0025]
Here, the presence or absence of inclusion of the second hard phase 4 in the diamond particles 2 is based on the contrast by the reflected electron image (BEI) in the scanning electron microscope (EPMA) photograph in the cross section of the composite sintered body, or the electron probe microanalysis method. (EPMA) can be quantified by composition mapping, and includes at least one selected from the group of metals in groups 4a, 5a, and 6a of the periodic table in which 80% or more of the outer peripheral surface of the diamond particle 2 is included. The state in contact with the carbides and carbonitrides of the above metal elements. According to the present invention, the second hard phase 4 is at least one selected from the group consisting of carbides, nitrides and carbonitrides of the periodic table 4a, 5a, 6a metal other than the first hard phase 2, so-called so-called It consists of B1 type solid solution.
[0026]
Further, since the concentration of the second hard phase 4 including the diamond particles 3 gradually decreases from the outer peripheral surface of the diamond particles 3 toward the binding phase 5, the bonding force of the diamond particles 3 to the sintered body 1 is increased. This further increases and the diamond particles 3 can be further prevented from falling off. This concentration distribution can be measured with a scanning electron microscope (EPMA).
[0027]
Here, in the present invention, the ratio D ₂ / D ₁ between the average diameter D ₁ of the core material and the average thickness D ₂ of the skin material 8 is 0.05 to 0.5 in terms of the balance of hardness, strength, and toughness. It is desirable that In the present invention, when the core material 7 has a shape other than a circle, the average diameter D1 can be estimated by calculating the average area from the area of each core material 7 and regarding the core material 7 as a circle. Further, the average thickness D2 of the skin material 8 can be calculated by averaging the shortest distances between the core materials 7.
[0028]
Manufacturing Method Next, a method for manufacturing the composite sintered body of the present invention will be described based on the schematic diagram of FIG.
[0029]
(A) Process First, at least one powder selected from the group of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals having an average particle size of 0.3 to 3 μm as a core material is 40 to 90% by volume, 5-15% by volume of iron group metal powder having an average particle size of 10 μm or less, and 5-50% by volume of coated diamond particles having an average particle size of 0.3-30 μm were mixed. Add an organic binder such as paraffin wax, polystyrene, polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol, dibutyl phthalate, and knead, press molding, extrusion molding or casting molding, etc. A cylindrical core material molding 12 is produced by the molding method described above.
[0030]
Here, in order to obtain a homogeneous composite molded body by coextrusion molding to be described later, it is desirable that the amount of the organic binder added is 30 to 70% by volume, particularly 40 to 60% by volume.
[0031]
(B) On the other hand, the raw material powder forming the skin material having a composition different from that of the core material is mixed, kneaded with the above-mentioned binder, and formed into a half cylindrical shape by a molding method such as press molding, extrusion molding or casting molding. Two skin member molded bodies 13 are produced, and a composite molded body 11 in which the skin material molded bodies 13 are arranged so as to cover the outer periphery of the core material molded body 12 is produced (see FIG. 2A). .
[0032]
The core molded body 12 and the skin member molded body 13 are coextruded with the composite molded body 11 by using an extrusion molding machine 14, thereby forming the skin member molded body 13 around the core material molded body 12. A composite fiber molded body 15 that has been stretched to a thin diameter is coated (see FIG. 2B). Further, in order to produce the multi-filament structure convergent composite fiber body 16, a plurality of the co-extruded long composite fiber molded bodies 15 may be converged and co-extruded again (see FIG. 2C). ).
[0033]
Further, the elongated elongated composite fiber molded body 15 may be co-extruded again if desired, and formed into a long shape having a circular, triangular, or quadrangular cross section. Further, as shown in FIG. 3, the long composite fiber molded bodies 15 are aligned to form a sheet 17, and a plurality of sheets 17 are formed so that the long composite fiber molded bodies 15 are parallel to each other, straight, or 45 °. It is also possible to form laminated bodies 18a to 18c that are laminated so as to form a predetermined angle, and it is also possible to mold the laminated body into an arbitrary shape by a molding method such as a known rapid protodiving method. . Furthermore, the above-described aligned sheet or a sheet of hard composite sintered body obtained by slicing the sheet in the cross-sectional direction can be bonded to or bonded to the surface of a conventional hard alloy (lumped body) such as cemented carbide. is there.
[0034]
(C) Process After carrying out the binder removal treatment for heating or holding at 300 to 700 ° C. for 10 to 200 hours for any one of the composite fiber molded body 15, the bundled fiber molded body 16, the sheet 17, and the laminated body 18, or in an inert atmosphere at a predetermined temperature, it was a hard composite sintered body or the present invention the multifilament type by firing time can be made rigid composite structure.
[0035]
According to the present invention, when the same metal powder as the metal component of the first hard phase 2 or the second hard phase 4 added in the core material 7 is added, it remains as a residue of the organic binder during sintering. By reacting with the residual carbon to generate carbides, it is possible to reduce the residual residual carbon, and to suppress shrinkage associated with the sintering of the core material 7, thereby reducing the core material 7 and the skin material 8. Residual stress generated between them can be reduced and peeling can be prevented.
[0036]
Furthermore, according to the present invention, in order to stably and firmly bond the diamond particles 3 in the hard composite sintered body 1, for example, in the case of electric current pressure sintering, the sintering temperature is the same as that during pressure sintering. 1300 to 1450 ° C., particularly 1300 to prevent the iron group metal from exuding and diffusing between the core material 7 and the skin material 8 to prevent the composition of the core material 7 and the skin material 8 from being controlled. It is desirable that it is 1400 degreeC.
[0037]
In view of densification of the sintered body 1 and control of decomposition of the diamond particles 3, the holding time at the sintering temperature is preferably 20 seconds or more and 10 minutes or less, particularly 1 to 5 minutes. Furthermore, it is desirable that the applied pressure is 10 to 100 MPa in terms of densification of the sintered body 1, and a special sintering apparatus is required to increase the applied pressure to a pressure exceeding 100 MPa, which increases the manufacturing cost.
[0038]
【Example】
(Example)
The WC powder with an average particle diameter of 1.5 μm, the Co powder with an average particle diameter of 1 μm, the TiC powder with an average particle diameter of 2 μm, and the metal W powder with an average particle diameter of 1 μm are weighed in the proportions shown in Table 1 and an attritor is used. The mixture was pulverized and mixed to prepare a hard member raw material powder to be a matrix.
[0039]
On the other hand, diamond particles coated with the film thickness and film type shown in Table 1 were added to the diamond particles by a known ion plating method at a ratio shown in Table 1 and mixed. Then, cellulose and polyethylene glycol as an organic binder and polyvinyl alcohol as a solvent were added together in the same amount as the raw material powder and kneaded, and extruded into a cylindrical shape to produce a core molded body.
[0040]
On the other hand, sample No. Two half-cylindrical shaped members for skin members are produced by extrusion molding using a mixed powder consisting of 10 compositions, and are arranged so as to cover the outer periphery of each core material shaped body shown in Table 1 above. A molded body was produced.
[0041]
Then, the composite molded body is extruded to produce a composite molded body in which the core material and the skin material are extruded and stretched, and then the 100 composite molded bodies that have been stretched are converged and again put into the extruder. It was inserted and co-extruded again to produce a multifilament type bundled fiber molded body.
[0042]
[Table 1]

[0043]
Next, the multifilament type converged fiber molded body is cut to a length of 50 mm and aligned in parallel to form a sheet, and the 6 sheets of the hard composite fiber sintered bodies in the adjacent sheets are 45 ° apart. A laminated molded body having a rectangular parallelepiped shape was manufactured by laminating so as to have an angle of.
[0044]
Thereafter, the binder was debindered by raising the temperature of the laminate to 300 to 700 ° C. over 100 hours, and then loaded into a graphite mold and applied with a pressure of 1.3 Pa (0.01 Torr) or less. Sintering was performed by applying a direct current under a pressure of 20 MPa. The heating rate was 100 ° C./min up to 1350 ° C., held at that temperature for 3 minutes, and then cooled at a rate of 50 ° C./min. The sintered body thus obtained had a good appearance without cracks. After removing the black skin (surface alteration) of these sintered bodies, the specific gravity was measured by the Archimedes method. All of the sintered bodies 1 to 5 were dense and had a theoretical density of 98% or more. Sample No. The density of 6-9 was about 95%.
[0045]
A 3 × 4 × 12 mm sample was cut out from the obtained hard composite sintered body, and a hard composite sintered body of 3 × 4 mm was placed on a disc-shaped SiC grindstone having a diameter of 20 mm rotating at the axis center at 20 m / min. A wear resistance test was performed to measure the amount of wear when the surface was pressed at a pressure of 20 N for 10 minutes. As an evaluation method, No. is used as a standard sample. No. 10 when the wear amount of the 10 samples is 100. The amount of wear of the sintered bodies 1 to 9 was calculated as a specific amount of wear and expressed as wear resistance.
[0046]
Next, this polished surface is mirror-finished, and observed with a scanning electron microscope (SEM), whether there is an inclusion layer on the outer peripheral surface of the diamond particles in the hard composite sintered body, and the inclusion ratio / average thickness of the inclusion layer Was measured by an image analysis method, and the content of free carbon was specified according to ISO 4505. In the present invention, the evaluation of free carbon was determined as C00 for a sample in which precipitation of free carbon was not observed in a 1000 times scanning electron micrograph of the cross section of the sintered body. In addition, for the sample in which the inclusion phase was present, the wavelength dispersion type X-ray microanalysis line analysis was performed on the vicinity thereof, and the presence or absence of a composition gradient in the vicinity of the inclusion layer region was measured. In each sample, the ratio (D ₂ / D ₁ ) between the average diameter D ₁ of the core material and the thickness D _{2 of the} skin material was 0.1. Furthermore, the fracture toughness value was measured by the IF method according to JIS R1607.
[0047]
Further, the sample was processed into a length of 3 mm × 4 mm × span 10 mm, and a three-point bending strength test according to JISR1601 was performed. These results are shown in Table 2.
[0048]
[Table 2]

[0049]
As shown in the results of Table 2, according to the present invention, diamond particles obtained by coating the outer peripheral surface with periodic table 4a, 5a, and 6a group metals are used as raw materials, and diamond particles are contained inside the hard sintered body, and free carbon Of sample No. About 1-5, it has confirmed that it was excellent in abrasion resistance, fracture toughness, and intensity | strength.
[0050]
The sample using the present invention has a structure in which dispersed diamond particles are included in the B1-type solid solution phase, so that the bond strength with the hard sintered matrix is increased, and the wear resistance is maintained while maintaining fracture toughness and strength. Can be remarkably improved. In particular, sample no. 1, 2, 4, and 5 can obtain further excellent bonding strength, and wear resistance is improved.
[0051]
On the other hand, sample No. using as a raw material a diamond powder that is not coated with anything or whose outer peripheral surface is coated with a compound other than the periodic table 4a, 5a, or 6a group metal. As for Nos. 6 to 9, the graphite phase was precipitated on the outer periphery of the diamond particles dispersed in the hard sintered body, and the fracture toughness and strength were low. Furthermore, sample no. Regarding Nos. 8 and 9, especially in the graphite phase, the diamond particles dropped off during the wear test, and sample Nos. Of cemented carbide containing no diamond particles in the core material as a standard sample. The result was inferior to 10.
[0052]
【The invention's effect】
As described above in detail, according to the hard composite sintered body of the present invention, in the hard alloy raw material powder as the core material of the composite sintered body produced using a large amount of organic binder, the periodic table 4a, 5a, 6a. By adding and mixing diamond particles coated with at least one metal selected from the group of group metals, the diamond particles are prevented from being decomposed and graphitized during firing, and the core material is made from 5 to 50 diamond particles. A hard composite sintered body having a volume% content and free carbon of C02 or less, having excellent wear resistance, and strength and toughness equivalent to cemented carbide can be obtained. It is done.
[Brief description of the drawings]
1A is a schematic cross-sectional view showing an example of a hard composite sintered body according to the present invention, and FIG.
FIG. 2 is a schematic view showing a production process of the hard composite sintered body of the present invention.
FIG. 3 is a schematic view showing an arrangement example of the hard composite sintered body of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hard compound sintered compact 2 1st hard phase 3 Diamond particle 4 2nd hard phase 5 Bonding phase 7 Core material 8 Skin material 11 Molded body 12 Molded body 13 Core material molded body 14 Extruder 15 Composite molding Body 16 Composite molded body 17 of multifilament structure Sheet molded body 18 Laminated molded body

Claims (9)

1st hard phase 50-95 volume% which consists of either tungsten carbide, titanium nitride, or titanium carbonitride, 5 to 50 volume% of diamond particles, and periodic table 4a, 5a other than the said 1st hard phase , carbides 6a group metal, nitride and at least one second hard phase 0-15% by volume selected from the group consisting of carbonitrides attached at binder phase consisting of iron group metals, the diamond particles 60 % Of a long core material comprising a hard sintered body in which an outer peripheral surface of at least% is encompassed by the second hard phase and the amount of free carbon defined by the porosity of the ISO 4505 alloy is C02 or less. the outer peripheral surface, the hard composite sintered, characterized in that it consists of multi-filament structure in which a plurality of converging composite fiber formed by coating the skin material consisting of hard sintered bodies having a composition different from the core material . Hard composite sintered body according to claim 1, wherein the coating thickness of the second hard phase including the diamond particles, characterized in that a 0.1 to 5 [mu] m. Claim 1 or 2 hard composite sintered body according from the outer peripheral surface toward the binder phase characterized in that it decreases gradually in the concentration of the second hard phase diamond particles including the diamond particles. Rigid composite structure having a hard composite sintered body according to any one of claims 1 to 3. (A) Periodic Tables 4a, 5a, 6a Group metal carbides, nitrides and carbonitrides, at least one powder selected from the group consisting of iron group metal powders, Periodic Tables 4a, 5a, 6a group metals A step of forming a core material by forming a mixture of diamond particles coated with at least one metal selected from the group, and an organic binder into a long shape,
(B) A composite molded body formed by molding a skin material molded body having a composition different from that of the molded body in the step (a) and covering the outer periphery of the core body molded body in the step (a). Producing and producing a converged composite fiber body having a multifilament structure in which a plurality of the composite molded bodies are converged; and
(C) calcining the convergent composite fiber body , 50 to 95% by volume of a first hard phase made of any of tungsten carbide, titanium nitride, or titanium carbonitride, and 5% by volume or more and less than 50% by volume of diamond particles; From the iron group metal, at least one second hard phase selected from the group consisting of carbides, nitrides, and carbonitrides of the periodic table 4a, 5a, 6a metal other than the first hard phase is selected from the group consisting of iron group metals. The outer peripheral surface of 60% or more of the diamond particles is contained by the second hard phase, and the amount of free carbon defined by the porosity of the ISO 4505 alloy is C02 or less. A multifilament structure in which a plurality of composite fibers are formed by covering the outer peripheral surface of a long core made of a hard sintered body with a skin material made of a hard sintered body having a composition different from that of the core. Method for producing a hard composite sintered body, characterized by comprising a step of preparing a hard composite sintered body, characterized in that Ranaru. The hard coating material according to claim 5 , wherein a coating thickness of at least one metal selected from the group of metals of the periodic table 4a, 5a, 6a coating the outer peripheral surface of the diamond particles is 0.1 to 3 µm. A method for producing a composite sintered body. The method for producing a hard composite sintered body according to claim 5 or 6 , wherein in the step (c), the metal covering the diamond particles is carbonized during firing. The method for producing a hard composite sintered body according to any one of claims 5 to 7, wherein the organic binder in the step (a) is added at a ratio of 30 to 70% by volume with respect to the entire mixture. In the step (a), the periodic table 4a, 5a, 6a group metal powder is further added at a ratio of 1 to 20% by mass, and in the step (c), a decomposition component in which the diamond powder decomposes upon firing; The method for producing a hard composite sintered body according to any one of claims 5 to 8, wherein the metal powder is fired so as to react and carbonize and expand in volume.

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