JPH07242980A - Cemented carbide with high toughness - Google Patents

Abstract

PURPOSE:To inhibit coagulation and grain growth and to improve the toughness, heat resistance, and wear resistance of a cemented carbide by using, as solid solutions, a composite powder previously allowed to adhere to the surface of WC, in a cemented carbide. CONSTITUTION:In a cemented carbide in which a hard phase is composed of WC of >=0.5mum average grain size and one or >=2 solid solutions selected from the carbides, nitrides, and carbonitrides of the group IVa, Va, and IVa metal elements and having <=0.2mum average grain size and a binding phase is composed of iron group metal, a composite powder previously allowed to adhere to the surface WC is used as solid solutions. Further, most of them exist in the state adhering to the surface of WC. By this method, mutual coagulation of B type solid solution substances can be inhibited. The contacting part between WC and WC can be reduced, and the toughness, heat resistance, and wear resistance of the cemented carbide can be improved.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は切削加工、塑性加工、耐
摩耗部材などに用いられる高靱性超硬合金に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high toughness cemented carbide used for cutting, plastic working, wear resistant members and the like.

【０００２】[0002]

【従来の技術】超硬は硬質相がＷＣと周期律表の４Ａ、
５Ａ、６Ａ族の金属元素の炭化物、窒化物、炭窒化物か
ら選ばれた１種または２種以上の固溶体硬質物質、いわ
ゆるＢ１型固溶体からなる耐熱性を重視したＰ種超硬と
硬質相がＷＣのみからなる靱性を重視した、いわゆるＫ
種超硬の２種に分類される。Ｂ１型固溶体はＷＣに比べ
て耐熱性は優れるものの靱性は劣るために上記のように
大別されるといわれている。2. Description of the Related Art Carbide has a hard phase of WC and 4A of the periodic table,
One or more solid solution hard substances selected from carbides, nitrides, and carbonitrides of 5A and 6A group metal elements, which are so-called B1 type solid solutions, are P type cemented carbides and hard phases that emphasize heat resistance. So-called K that emphasizes toughness consisting of WC only
It is classified into two kinds of seed carbide. It is said that B1 type solid solutions are roughly classified as described above because they have excellent heat resistance as compared with WC but have poor toughness.

【０００３】しかしながら超硬も他の工業材料と同様、
常により強靱のものが求められる。Ｐ種超硬については
言えばより靱性のある材種の要望が極めて強い。このた
め従来より種々の改良、検討がなされてきたが、まだま
だ不十分なのが実情である。超硬は一般にＷＣ粉末や他
のＢ型固溶体を構成する硬質物質粉末及び鉄族金属を所
定の比に混合し、焼結することによって製造される。焼
結後のミクロ組織特に硬質物質の粒径と分散度は材料の
特性を左右するものであるが、このうち粒径はほぼ使用
した原料粉末の粒径に依存する。そこでＷＣに比べて靱
性の劣るＢ型固溶体構成原料はできるだけ微細なものを
使用して靱性の改善を図ってきたのが一般的である。し
かしながらその効果が不十分であった理由はＢ型固溶体
構成原料の分散が悪くて凝集してしまうこと、また焼結
過程で粒成長が起こり易く結果的に粗大なＢ型固溶体硬
質相となってしまう点にあることを発明者らは見出だし
た。他方Ｋ種超硬についてはより強靱なもの、より耐熱
性のあるもの、より耐摩耗性のあるものなど多様な要求
がある。しかしながらＫ種超硬は前述の如く基本的には
ＷＣとＣｏの単純な複合材料であるためその性質を飛躍
的に向上させることは困難であった。However, cemented carbide, like other industrial materials,
Stronger ones are always required. As for P-type cemented carbide, there is an extremely strong demand for grades with higher toughness. Therefore, various improvements and investigations have been made in the past, but the fact is that they are still insufficient. Cemented carbide is generally produced by mixing WC powder and other hard material powders forming a B-type solid solution and an iron group metal in a predetermined ratio and sintering. The microstructure after sintering, particularly the particle size and dispersity of the hard substance, influences the characteristics of the material, and of these, the particle size depends almost on the particle size of the raw material powder used. Therefore, it has been generally attempted to improve the toughness by using a B-type solid solution constituent raw material having inferior toughness as compared with WC, as fine as possible. However, the reason why the effect is insufficient is that the B-type solid solution constituent raw material is poorly dispersed and aggregates, and grain growth easily occurs in the sintering process, resulting in a coarse B-type solid solution hard phase. The inventors have found that there is a point at which it ends up. On the other hand, regarding K-type carbide, there are various requirements such as toughness, heat resistance, and wear resistance. However, since the K-type cemented carbide is basically a simple composite material of WC and Co as described above, it was difficult to dramatically improve its properties.

【０００４】[0004]

【発明が解決しようとする課題】本発明は従来の技術で
は困難であったＰ種超硬の靱性の飛躍的向上、Ｋ種超硬
の特に耐熱性、耐摩耗性改良を新規な原料粉末を用いる
ことによって達成しようするものである。DISCLOSURE OF THE INVENTION The present invention provides a new raw material powder for which the toughness of P-type cemented carbide, which has been difficult to achieve by the conventional techniques, is dramatically improved, and particularly the heat resistance and wear resistance of K-type cemented carbide are improved. It is something that is achieved by using it.

【０００５】[0005]

【課題を解決するための手段】Ｐ種超硬の靱性を阻害し
ているのはＢ型固溶体硬質相の凝集と粒成長である。発
明者らは粗粒に微粒を固着させた新規な複合原料粉末を
用いることでこの凝集と粒成長を抑制することに成功し
た。具体的には粗粒のＷＣの表面に超微粒のＢ型固溶体
構成硬質物質を固着させた複合粉末あるいは逆にＢ型固
溶体構成硬質原料粉末の表面に超微粒のＷＣを固着させ
た複合粉末などを用いると凝集と粒成長が抑制されるの
である。前者ではＷＣ表面への固着力が大きいためにＢ
型固溶体物質どうしの凝集が抑制され、後者ではＷＣと
鉄族金属との濡れ性が良いため凝集が抑制されるのであ
る。粗粒に超微粒を固着させた複合粉末は、例えば”化
学工学シンポジウムシリーズ ＶＯＬ．２５ ＮＯ．１
ＰＡＧＥ４７−５１ １９９３”にあるように超微粒
子を発生させるプラズマ炎の中に粗粒粉末を連続的に導
入することにより粗粒粉末の表面に超微粒子を固着させ
る乾式法や粉体と液体を同時に噴霧乾燥して粉体の表面
に超微粒子を固着させる湿式法により製造することがで
きる。The toughness of P-type cemented carbide is hindered by the aggregation and grain growth of the B-type solid solution hard phase. The inventors have succeeded in suppressing this aggregation and grain growth by using a novel composite raw material powder in which fine grains are fixed to coarse grains. Specifically, composite powder in which ultrafine particles of B-type solid solution constituent hard substance are fixed to the surface of coarse particles of WC, or conversely, composite powder in which ultrafine particles of WC are fixed to the surface of B-type solid solution constituent hard raw material powder, etc. When is used, aggregation and grain growth are suppressed. In the former case, since the adhesion to the WC surface is large, B
Aggregation of the mold solid solution substances is suppressed, and in the latter case, aggregation is suppressed due to good wettability between WC and the iron group metal. The composite powder in which ultrafine particles are fixed to coarse particles is, for example, “Chemical Engineering Symposium Series VOL.25 NO.1”.
As described in PAGE 47-51 1993 ", a dry method in which coarse particles are adhered to the surface of coarse particles by continuously introducing coarse particles into a plasma flame that generates ultrafine particles, or a powder method and a liquid are simultaneously applied. It can be produced by a wet method of spray-drying and fixing ultrafine particles on the surface of the powder.

【０００６】[0006]

【作用】特にプラズマを用いてＷＣの超微粒子を発生さ
せるとプラズマの超高温活性化状態からの超急冷効果に
より全く新規な物質が合成されることが知られている。
すなわち通常のｈｃｐ構造ではなくｆｃｃ構造のＷＣが
合成される。このｆｃｃ−ＷＣはＣ／Ｗ原子数比が０．
６〜０．８の時に合成されるもので、硬さがｈｃｐ−Ｗ
Ｃよりも高く焼結時の粒成長も少ない良好な性質を有す
る。このため粗粒のＷＣの表面にこのｆｃｃ−ＷＣを固
着させた新規原料粉末を用いると特異な効果を発揮す
る。In particular, it is known that when WC ultrafine particles are generated by using plasma, a completely new substance is synthesized by the superquenching effect from the ultrahigh temperature activated state of plasma.
That is, the WC having the fcc structure is synthesized instead of the normal hcp structure. This fcc-WC has a C / W atomic number ratio of 0.
It is synthesized when it is 6 to 0.8, and its hardness is hcp-W.
It has better properties than C and less grain growth during sintering. Therefore, a unique effect is exhibited by using the new raw material powder in which the fcc-WC is adhered to the surface of the coarse WC.

【０００７】すなわち従来のＫ種超硬においてもミクロ
組織を詳細に観察するとかなりの部分でＷＣとＷＣが接
触していることがわかる。このＷＣとＷＣの接触の多少
がＫ種超硬の靱性と耐熱性を左右するのである。過大の
外力が超硬に加わるとマイクロクラックはまずＷＣとＷ
Ｃの接触部に発生するため、接触部が多いほど靱性が低
下する。また外熱と外力が付加されると熱クラックが発
生するが、このクラックはＷＣとＷＣの接触部及びＣｏ
／ＷＣ界面でまずは発生する。Ｃｏ／ＷＣ界面は両者が
入り組んでいるほど熱クラックの発生が抑制されること
を発明者らは見出だしている。粗粒／微粒複合粉末を使
用するとＷＣ／ＷＣ接触部が減少するとともにＷＣ／Ｃ
ｏ界面がいり込むことになる。またｆｃｃ−ＷＣの硬さ
が著しく高いため合金自体の硬度が向上する。以上の結
果超硬の靱性、耐熱性、耐摩耗性をともに向上させるこ
とができる。なおＢ型固溶体構成超微粒子の非金属／金
属原子数比も０．６〜０．８とすると硬度が上昇し耐摩
耗性が向上する効果がある。硬度が上昇する理由は格子
欠陥が増加し転位の移動が困難になったためと推測され
る。以下 実施例でその効果を説明する。In other words, even in the conventional K-type cemented carbide, observing the microstructure in detail, it can be seen that WC and WC are in contact with each other in a considerable part. The degree of contact between the WC and the WC determines the toughness and heat resistance of the K-type carbide. When an excessive external force is applied to the carbide, the microcracks will be WC and W
Since it occurs at the contact portion of C, the more the contact portion, the lower the toughness. Also, when external heat and external force are applied, thermal cracks occur, but these cracks are caused by the contact portion between WC and WC and Co.
First occurs at the / WC interface. The inventors have found that the more complicated the Co / WC interface is, the more the generation of thermal cracks is suppressed. Use of coarse / fine composite powder reduces WC / WC contact area and increases WC / C
o The interface will be rubbed in. Further, since the hardness of fcc-WC is extremely high, the hardness of the alloy itself is improved. As a result, it is possible to improve the toughness, heat resistance, and wear resistance of cemented carbide. When the non-metal / metal atom number ratio of the B-type solid solution constituent ultrafine particles is set to 0.6 to 0.8, the hardness is increased and the abrasion resistance is improved. It is presumed that the hardness is increased because the number of lattice defects increases and it becomes difficult for dislocations to move. The effect will be described below in Examples.

【０００８】[0008]

【実施例】プラズマを用いた乾式法（１）、サスペンシ
ョンを用いた湿式法（２）で各種粗粒に各種超微粒を固
着させた複合粉末を作製した。表１にその仕様を示す。[Examples] Composite powders were prepared by adhering various ultrafine particles to various coarse particles by a dry method (1) using plasma and a wet method (2) using a suspension. Table 1 shows the specifications.

【０００９】[0009]

【表１】 [Table 1]

【００１０】次に表１の複合粉末を適宜使用して配合量
を調整し、アトライター混合、スプレイドライ後、焼結
をおこなった。組成は、 62%WC-10%TIC-10%TaC-5%NbC-8%Co .................. .(A) 67%WC-8%TiC-2%TiN-8%TaC-5%NbC-10%Co................(B) 62%WC-10%TiC-9.0%TaC-0.5%ZrC-0.5%VC-5%NbC-8%Co.....(C) 62%WC-10%TiC-9.5%TaC-0.5%Cr3C2-5%NbC-8%Co..........(D) 93%WC-7%Co.........................................(E) とした。同時に複合粉末を使用しない従来の方法でも試
料を作製し、比較した。表２に配合仕様及び材料特性を
示した。Next, the compounding powders in Table 1 were appropriately used to adjust the blending amount, and the mixture was mixed with an attritor, spray-dried, and then sintered. The composition is 62% WC-10% TIC-10% TaC-5% NbC-8% Co .................. (A) 67% WC-8% TiC-2% TiN-8% TaC-5% NbC-10% Co ................ (B) 62% WC-10% TiC-9.0% TaC-0.5% ZrC-0.5% VC-5% NbC-8% Co ..... (C) 62% WC-10% TiC-9.5% TaC-0.5% Cr3C2-5% NbC-8% Co ...... .... (D) 93% WC-7% Co .................................. ..... (E) At the same time, samples were prepared and compared by the conventional method that does not use the composite powder. Table 2 shows the compounding specifications and material characteristics.

【００１１】[0011]

【表２】 [Table 2]

【００１２】次に切削チップ（ＳＮＧＮ４３２）を作製
し下に示す条件で切削テストを行ない、切り刃に発生し
た熱クラックの本数を調査して耐熱性を比較した。 切削条件 フライス加工 被削材 ＳＣＭ４４０ 被削材形状 幅１００ｍｍ 長さ４００ｍｍ 切削速度 １００ｍ／ｍｉｎ 送り ０．２ｍｍ／ｒｅｖ 切り込み ２ｍｍ 切削時間 ８０ｍｉｎNext, a cutting tip (SNGN432) was produced and a cutting test was conducted under the conditions shown below to examine the number of thermal cracks generated in the cutting edge and compare the heat resistance. Cutting conditions Milling Work material SCM440 Work material shape Width 100mm Length 400mm Cutting speed 100m / min Feed 0.2mm / rev Depth of cut 2mm Cutting time 80min

【００１３】[0013]

【表３】 [Table 3]

【００１４】[0014]

【発明の効果】このように複合粉末を使用して作製した
材料は靱性、硬さ、耐熱性を共に向上させることが出来
る。複合粉末を用いた材料はミクロ組織を観察すると、
粗粒の周辺に微粒が囲むように存在しており、これが粗
粒どうしの接触を減少させている。また硬質相／金属界
面は凹凸が多い。これが合金の特性を向上させた原因で
ある。As described above, the material produced by using the composite powder can have improved toughness, hardness and heat resistance. When observing the microstructure of the material using the composite powder,
Fine particles are present around the coarse particles so as to surround them, and this reduces the contact between the coarse particles. Further, the hard phase / metal interface has many irregularities. This is the reason why the properties of the alloy are improved.

Claims (7)

【特許請求の範囲】[Claims] 【請求項１】 硬質相の平均粒径が０．５μｍ以上のＷ
Ｃと平均粒径０．２μｍ以下の周期律表の４Ａ、５Ａ、
６Ａ族の金属元素の炭化物、窒化物、炭窒化物から選ば
れた１種または２種以上の固溶体で構成され、結合相が
周期律表の鉄族金属よりなる超硬合金であって、該固溶
体は予めＷＣの表面に固着させた複合粉末を使用し、か
つその大部分がＷＣの表面に付着して存在することを特
徴とする高靱性超硬。1. A W having an average grain size of the hard phase of 0.5 μm or more.
C and 4A and 5A of the periodic table with an average particle size of 0.2 μm or less,
A cemented carbide that is composed of one or more solid solutions selected from carbides, nitrides, and carbonitrides of 6A group metal elements and has a binder phase made of an iron group metal of the periodic table, A high toughness cemented carbide is characterized in that the solid solution uses a composite powder which is fixed to the surface of the WC in advance, and most of it is present by adhering to the surface of the WC. 【請求項２】 硬質相が平均粒径が０．２μｍ以下のＷ
Ｃと平均粒径０．５μｍ以上の周期律表の４Ａ、５Ａ、
６Ａ族の金属元素の炭化物、窒化物、炭窒化物から選ば
れた１種または２種以上の固溶体硬質物質で構成され、
結合相が周期律表の鉄族金属よりなる超硬合金であっ
て、ＷＣは予め固溶体硬質物質の表面に固着させた複合
粉末を使用し、かつその大部分が該固溶体物質の表面に
付着して存在することを特徴とする高靱性超硬。2. The hard phase is W having an average particle size of 0.2 μm or less.
C and 4A, 5A of the periodic table with an average particle size of 0.5 μm or more,
Composed of one or more solid solution hard substances selected from carbides, nitrides and carbonitrides of 6A group metal elements,
The binder phase is a cemented carbide composed of an iron group metal of the periodic table, WC uses a composite powder that is fixed in advance to the surface of a solid solution hard substance, and most of it adheres to the surface of the solid solution substance. High toughness carbide that is present as 【請求項３】 硬質相が平均粒径が０．２μｍ以下のｆ
ｃｃ構造のＷＣと平均粒径０．５μｍ以上のｈｃｐ構造
のＷＣで構成され、結合相が周期律表の鉄族金属よりな
る超硬合金であって、ｆｃｃ構造のＷＣは予めｈｃｐ構
造のＷＣ表面に固着させた複合粉末を使用した結果、そ
の大部分がｈｃｐ構造のＷＣの表面に付着して存在する
ことを特徴とする高靱性超硬。3. The hard phase having an average particle size of 0.2 μm or less f
WC structure and WC with hcp structure having an average particle size of 0.5 μm or more, the binder phase is a cemented carbide composed of an iron group metal of the periodic table, and the WC of the fcc structure is the WC of the hcp structure in advance. High toughness cemented carbide characterized by the fact that the majority of the composite powder adhered to the surface of the WC having the hcp structure is present as a result of using the composite powder fixed to the surface. 【請求項４】 硬質相が平均粒径が０．２μｍ以下のｆ
ｃｃ構造のＷＣと平均粒径０．５μｍ以上のｈｃｐ構造
のＷＣと周期律表の４Ａ、５Ａ、６Ａ族の金属元素の炭
化物、窒化物、炭窒化物から選ばれた１種または２種以
上の固溶体硬質物質で構成され、結合相が周期律表の鉄
族金属よりなる超硬合金であって、ｆｃｃ構造のＷＣは
予めｈｃｐ構造のＷＣ表面に固着させた複合粉末を使用
した結果、その大部分がｈｃｐ構造のＷＣの表面に付着
して存在することを特徴とする高靱性超硬。4. The hard phase has an average particle size of 0.2 μm or less f
WC of cc structure and WC of hcp structure having an average particle size of 0.5 μm or more and one or more selected from carbides, nitrides and carbonitrides of metal elements of Groups 4A, 5A and 6A of the periodic table. Which is a cemented carbide composed of an iron group metal of the Periodic Table, the WC of the fcc structure is a composite powder fixed in advance on the WC surface of the hcp structure, High toughness cemented carbide characterized in that most of it is present on the surface of WC with hcp structure. 【請求項５】 硬質相が平均粒径が０．２μｍ以下のＷ
Ｃと平均粒径０．５μｍ以上の周期律表の４Ａ、５Ａ、
６Ａ族の金属元素の炭化物、窒化物、炭窒化物から選ば
れた１種または２種以上の固溶体硬質物質および平均粒
径が０．５μｍ以上のＷＣで構成され、結合相が周期律
表の鉄族金属よりなる超硬合金であって、平均粒径が
０．２μｍ以下のＷＣは予め固溶体硬質物質の表面に固
着させた複合粉末を使用した結果、その大部分が該固溶
体物質の表面に付着して存在することを特徴とする高靱
性超硬。5. The W having a hard phase having an average particle size of 0.2 μm or less.
C and 4A, 5A of the periodic table with an average particle size of 0.5 μm or more,
It is composed of one or more solid solution hard substances selected from carbides, nitrides, and carbonitrides of 6A group metal elements and WC having an average particle size of 0.5 μm or more, and a binder phase of the periodic table. A cemented carbide made of an iron group metal, WC having an average particle diameter of 0.2 μm or less is used as a result of using a composite powder which is fixed to the surface of a solid solution hard material in advance, and most of the WC is deposited on the surface of the solid solution material. High-toughness cemented carbide characterized by being adhered and present. 【請求項６】 請求項２〜５に記載の高靱性超硬おい
て、平均粒径が０．２μｍ以下のＷＣを構成する炭素の
原子数がタングステン原子数の８０〜６０％であること
を特徴とする高靱性超硬。6. The high toughness cemented carbide according to claim 2, wherein the number of carbon atoms constituting the WC having an average grain size of 0.2 μm or less is 80 to 60% of the number of tungsten atoms. Characteristic high toughness carbide. 【請求項７】 請求項２〜５に記載の高靱性超硬おい
て、固溶体硬質物質を構成する非金属元素の原子数が金
属元素原子数の８０〜６０％であることを特徴とする高
靱性超硬。7. The high toughness cemented carbide according to any one of claims 2 to 5, wherein the number of atoms of the non-metal element constituting the solid solution hard material is 80 to 60% of the number of metal element atoms. Tough cemented carbide.