JP2004345006A - Cutting tool of surface-coated cubic crystal boron nitride-based sintered material with hard coating layer achieving excellent chipping resistance in high speed heavy cutting work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool of surface-coated cubic crystal boron nitride-based sintered material with a hard coating layer achieving excellent chipping resistance in high-speed heavy cutting work. <P>SOLUTION: On the surface of a base, a hard coating layer of composite nitride of Ti, Al and Si is physically deposited in layer thickness of 0.5-10μm. In the hard coating layer, highest content points of Al and lowest content points of Al alternately exist at a prescribed interval in a layer thickness direction, and the content ratio of Ti and Al is varied from the highest content point of Al to the lowest content point of Al, and from the lowest content point of Al to the highest content point of Al in component concentration distribution structure. The highest content point of Al satisfies a formula of [Ti<SB>1-(X+Z</SB>)Al<SB>X</SB>Si<SB>Z</SB>] (X is 0.45-0.65, and Z is 0.01-0.15 by atomic ratio). The lowest content point of Al satisfies a formula of [Ti<SB>1-(Y+Z)</SB>Al<SB>Y</SB>Si<SB>Z</SB>]N (Y is 0.10-0.35, and Z is 0.01-0.15 by atomic ratio). The interval between the highest content point of Al and the lowest content point of Al adjoining each other is 0.01-0.1 μm in the hard coating layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１９】
【表２】

【００２０】
【表３】

【００２１】
【表４】

【００２２】
【表５】

【００２３】
この結果得られた本発明被覆ＢＮ基工具１〜１６を構成する硬質被覆層におけるＡｌ最高含有点とＡｌ最低含有点の組成、並びに比較被覆ＢＮ基工具１〜１６の硬質被覆層の組成について、厚さ方向に沿ってＴｉ、Ａｌ、およびＳｉ成分の含有量をオージェ分光分析装置を用いて測定したところ、本発明被覆ＢＮ基工具１〜１６の硬質被覆層では、Ａｌ最高含有点とＡｌ最低含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＴｉおよびＡｌ成分の含有割合がそれぞれ連続的に変化する成分濃度分布構造を有することが確認され、また硬質被覆層の平均層厚も目標層厚と実質的に同じ値を示した。
一方前記比較被覆ＢＮ基工具１〜１６の硬質被覆層では厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標層厚と実質的に同じ平均層厚を示すことが確認された。
【００２４】
【発明の効果】
表２〜５に示される結果から、硬質被覆層が層厚方向にＡｌ最低含有点とＡｌ最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有する本発明被覆ＢＮ基工具は、いずれも各種の鋼や鋳鉄などの切削加工を、高い発熱を伴なう高速で、かつ高い負荷のかかる高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するのに対して、硬質被覆層が層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ）Ｎ層または（Ｔｉ，Ａｌ，Ｓｉ）Ｎ層からなる比較被覆ＢＮ基工具においては、前記硬質被覆層が高温硬さと耐熱性を有するものの、十分な高温強度を具備するものでないために、チッピングが発生し、これが原因で比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆ＢＮ基工具は、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの切削加工を高速重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆ＢＮ基工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】比較被覆ＢＮ基工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer having excellent high-temperature strength, and excellent high-temperature hardness and heat resistance. Therefore, cutting of various types of steel and cast iron is particularly required at high speeds where generation of high heat is inevitable. A cutting tool made of a surface-coated cubic boron nitride-based sintered material that exhibits excellent chipping resistance even when it is performed under heavy cutting conditions such as high cutting and high feed with high load. BN base tool).
[0002]
[Prior art]
In general, a coated BN base tool has a throw-away tip that is detachably attached to the tip of a cutting tool for turning a work material such as various steels or cast irons, and the throw-away tip is detachably attached. Also, a throw-away end mill or the like that performs cutting in the same manner as a solid type end mill used for face milling, grooving, and shoulder machining is known.
[0003]
In addition, as a coated BN-based tool, it has excellent high-temperature hardness and heat resistance, but because of its low high-temperature strength, it has a high cutting speed but high-speed surface finishing under conditions where cutting and feeding are significantly reduced. A cutting tool made of a cubic boron nitride-based sintered material, which has been used only in the above, is used as a substrate (hereinafter referred to as a BN-based substrate), and on the surface of the BN-based substrate, for the purpose of improving the strength of the cutting tool itself,
Compositional formula: (Ti _1-X Al _X ) N (where X represents 0.45 to 0.65 in atomic ratio),
A hard coating layer made of a composite nitride of Ti and Al (hereinafter, referred to as (Ti, Al) N) satisfying the following conditions is physically deposited with an average layer thickness of 0.5 to 10 μm, and cuts under ordinary conditions are performed. A coated BN base tool is known in which cutting or chipping (small chipping) does not occur in the cutting edge portion even when continuous cutting or intermittent cutting of various kinds of steel or cast iron is performed by feed (for example, Patent Document 1).
[0004]
Further, the coated BN-based tool is charged with the above-described BN-based substrate in an arc ion plating apparatus, which is a kind of a physical vapor deposition apparatus, for example, schematically illustrated in FIG. For example, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which a Ti-Al alloy having a predetermined composition is set under a condition of, for example, a current of 150 A while being heated to a temperature of 530 ° C. At the same time, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of, for example, 2 Pa. On the other hand, the above-mentioned BN base substrate is subjected to, for example, a bias voltage of −100 V under the condition that It is also known to be manufactured by depositing a hard coating layer consisting of a (Ti, Al) N layer.
[0005]
[Patent Document 1]
JP-A-8-119774
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, but on the other hand, there is a strong demand for labor saving, energy saving, and lower cost for cutting. Although it tends to be performed under heavy cutting conditions, in the above-mentioned conventional coated BN base tool, there is no problem when this is used under normal cutting conditions, but cutting is performed at a high speed with high heat generation. In addition, when the cutting is performed under heavy cutting conditions such as high cutting and high feed with a high load, chipping (micro cracking) tends to occur especially due to insufficient high temperature strength of the hard coating layer, and heat resistance is also increased. Insufficiency leads to accelerated abrasion, so that at present the service life is reached in a relatively short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated BN-based tool in order to develop a coated BN-based tool in which the hard coating layer exhibits excellent chipping resistance especially in high-speed heavy cutting. As a result of conducting research, focusing on the constituent hard coating layer,
(A) The (Ti, Al) N layer constituting the hard coating layer of the conventional coated BN-based tool formed using the arc ion plating apparatus shown in FIG. 2 is substantially over the entire layer thickness. Has a uniform composition and therefore a uniform high-temperature hardness and heat resistance, and a high-temperature strength. For example, an arc having a structure shown in a schematic plan view in FIG. An ion plating apparatus, that is, a rotary table for mounting a BN-based substrate is provided at the center of the apparatus, and a Ti-Al-Si alloy having a relatively high Al content on one side and a rotary table An arc ion plating apparatus is used in which a Ti-Al-Si alloy having a low Al content is opposed to each other as a cathode electrode (evaporation source), and a predetermined distance in a radial direction from a central axis on the rotary table of the apparatus is used. At a distant position, a plurality of BN-based substrates are mounted in a ring shape along the outer peripheral portion. In this state, the atmosphere in the apparatus is set to a nitrogen atmosphere, the rotary table is rotated, and the thickness of the hard coating layer formed by vapor deposition is formed. An arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides while rotating the BN base substrate itself for the purpose of uniforming, and Ti and Al are formed on the surface of the BN base substrate. When a hard coating layer made of a composite nitride of Si [hereinafter, referred to as (Ti, Al, Si) N] is formed, the resulting (Ti, Al, Si) N layer is formed in a ring shape on a rotary table. When the disposed BN-based substrate comes closest to the cathode electrode (evaporation source) of the Ti-Al-Si alloy having a relatively high Al content on one side, an Al highest content point is formed in the layer. And B When the base substrate comes closest to the cathode electrode of the Ti-Al-Si alloy having a relatively low Al content on the other side, an Al lowest content point is formed in the layer. The Al maximum content point and the Al minimum content point alternately and repeatedly appear at predetermined intervals along the layer thickness direction, and the Al maximum content point from the Al maximum content point and the Al maximum content from the Al minimum content point. To have a component concentration distribution structure in which the content ratios of Ti and Al continuously change, respectively.
[0008]
(B) In the (Ti, Al, Si) N layer having the repeated and continuously changing component concentration distribution structure of the above (a), for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are adjusted, and the BN base substrate is formed. By controlling the rotation speed of the mounted rotary table,
The above Al maximum content point is
_{Formula: [Ti 1- (X + Z} ) Al X Si Z N] ( where in atomic ratio, X is 0.45 to 0.65, Z represents a 0.01 to 0.15),
The above Al minimum content point is
_{Formula: [Ti 1- (Y + Z} ) Al Y Si Z N] ( where in atomic ratio, Y is 0.10 to 0.35, Z represents a 0.01 to 0.15),
Each satisfying the above, and the distance in the thickness direction between the adjacent Al maximum content point and Al minimum content point is 0.01 to 0.1 μm,
In the Al highest content portion, the heat resistance of the conventional (Ti, Al) N layer is relatively higher than that of the conventional (Ti, Al) N layer, in combination with the heat resistance improving effect of the Si content. In the Al lowest content portion, the heat resistance is also improved by Si content, and the Al content ratio is lower and the Ti content ratio is higher than the Al highest content portion, so that the relatively high high-temperature strength is obtained. Is ensured, and the interval between these Al maximum content points and Al minimum content points is extremely small, so that in addition to excellent high-temperature hardness and heat resistance as the properties of the entire layer, it is possible to provide even higher high-temperature strength. Therefore, the coated BN-based tool including the (Ti, Al, Si) N layer having the hard coating layer has such a configuration that the cutting process of various kinds of steel and cast iron can be performed at a high speed with high heat generation. High load If you make heavy cutting conditions, such as mowing high cut and high feed also be like exhibits chipping resistance of the hard coating layer has excellent.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above research results, and a hard coating layer made of (Ti, Al, Si) N having a physical layer thickness of 0.5 to 10 μm is formed on the surface of a BN base substrate. In a coated BN base tool formed by evaporation,
The hard coating layer has an Al maximum content point and an Al minimum content point alternately and repeatedly provided at predetermined intervals along the layer thickness direction, and the Al maximum content point and the Al minimum content point, the Al From the lowest content point to the Al highest content point, the content ratios of Ti and Al each have a component concentration distribution structure that continuously changes,
Furthermore, the above Al maximum content point is
_{Formula: [Ti 1- (X + Z} ) Al X Si Z N] ( where in atomic ratio, X is 0.45 to 0.65, Z represents a 0.01 to 0.15),
The above Al minimum content point is
_{Formula: [Ti 1- (Y + Z} ) Al Y Si Z N] ( where in atomic ratio, Y is 0.10 to 0.35, Z represents a 0.01 to 0.15),
Respectively, and the interval between the adjacent Al maximum content point and Al minimum content point is 0.01 to 0.1 μm,
The present invention is characterized by a coated BN base tool in which a hard coating layer exhibits excellent chipping resistance by high-speed heavy cutting.
[0010]
Next, the reason why the configuration of the hard coating layer constituting the coated BN base tool of the present invention is limited as described above will be described.
(A) In the composition (Ti, Al, Si) N layer having the highest Al content, as described above, Ti improves high-temperature strength, Al improves high-temperature hardness and heat resistance, and Si coexists with Al. Has a function of further improving the heat resistance, and therefore has a relatively high high-temperature hardness and heat resistance at the highest Al content point where the content ratio of the Al component is high, and is used in high-speed cutting accompanied by high heat generation. Although it exhibits excellent abrasion resistance, if the X value indicating the Al content ratio is less than 0.45 in the ratio (atomic ratio, the same applies hereinafter) to the total amount of Ti and Si, desired high-temperature hardness and heat resistance are not achieved. On the other hand, when the X value is higher than 0.65, the lowering of the high-temperature strength of the layer itself is inevitable even if there is an adjacent Al minimum content point having high high-temperature strength. , This results in chipping etc. Since the more likely to occur, defining the X value as 0.45 to 0.65.
If the Z value indicating the Si content ratio is less than 0.01 in the total amount of Ti and Al, the desired effect of improving heat resistance cannot be obtained. On the other hand, if the Z value exceeds 0.15, the high temperature strength cannot be improved. Is rapidly reduced, so the Z value is set to 0.01 to 0.15.
[0011]
(B) Composition of Al minimum content point As described above, the Al maximum content point has relatively high high-temperature hardness and heat resistance, but is inferior in high-temperature strength. For the purpose of compensating, the content ratio of Ti is relatively high, and thereby the Al minimum content point which has excellent high-temperature strength is alternately interposed in the thickness direction. If the Y value indicating the Al content ratio is less than 0.10 in the ratio of the total amount of Ti and Si, the high-temperature hardness and heat resistance of the lowest Al content point are to be prevented. Is excessively low, which causes acceleration of wear. On the other hand, when the Y value exceeds 0.35, the high-temperature strength sharply decreases and chipping easily occurs in the cutting edge portion. 10 to 0.35 .
Further, the Z value indicating the Si content ratio is set to 0.01 to 0.15 for the same reason as in the case of the Al maximum content point described above.
[0012]
(C) Interval between the highest Al content point and the lowest Al content point If the interval is less than 0.01 μm, it is difficult to clearly form each point with the above composition, and as a result, the desired high-temperature hardness for the layer is obtained. In addition, heat resistance and high-temperature strength cannot be ensured, and if the distance exceeds 0.1 μm, each point has a disadvantage, that is, if the Al content is the highest, the high-temperature strength is insufficient, and the Al content is the lowest. For example, high-temperature hardness and insufficient heat resistance locally appear in the layer, which may cause chipping on the cutting edge or promote abrasion. .1 μm.
[0013]
(D) Average layer thickness of the hard coating layer If the average layer thickness is less than 0.5 μm, it is not possible to secure desired wear resistance. Since chipping is likely to occur, the average layer thickness is set to 0.5 to 10 μm.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated BN-based tool of the present invention will be specifically described with reference to examples.
As raw material powders, cubic boron nitride (hereinafter, referred to as c-BN) powder, titanium carbide (hereinafter, referred to as TiC) powder, and titanium nitride (hereinafter, referred to as c-BN) each having an average particle diameter in the range of 0.5 to 4 μm. , TiN) powder, titanium carbonitride (hereinafter referred to as TiCN) powder, tungsten carbide (hereinafter referred to as WC) powder, Al powder, Co powder, Ti ₃ Al powder which is an intermetallic compound powder of Ti and Al , TiAl powder, and TiAl ₃ powder, a composite metal nitride powder having a composition formula: Ti ₂ AlN, a titanium boride (hereinafter, referred to as TiB ₂ ) powder, an aluminum nitride (hereinafter, referred to as AlN) powder, boride aluminum (hereinafter, indicated by AlB ₂₎ powder, prepared powders (indicated by _Al 2 _{O 3)} of aluminum oxide, are blended raw material powder formulation compositions shown in Table 1, Bo After wet-mixing with a mill for 60 hours and drying, the mixture was press-molded at a pressure of 100 MPa into a green compact having a size of diameter: 50 mm × thickness: 1.5 mm. Sintering was performed in a vacuum atmosphere at a predetermined temperature in the range of 900 to 1300 ° C. for 60 minutes to obtain a pre-sintered body for a cutting blade, and this pre-sintered body was separately prepared, Co: 8 mass %, WC: remaining composition, and placed in a normal ultra-high pressure sintering apparatus in a state of being superimposed on a WC-based cemented carbide support piece having dimensions of 50 mm × thickness: 2 mm, Ultra-high pressure sintering under the conditions of pressure: 5 GPa, temperature: 1200 to 1400 ° C. and holding time: 0.7 hour, and after sintering, polishing the upper and lower surfaces using a diamond grindstone. Into a regular triangle with a side of 3mm by wire electric discharge machine WC having the following composition: Co: 5% by mass, TaC: 5% by mass, WC: Remaining composition and shape (regular triangle of thickness: 4.76 mm × side length: 12.7 mm) of CIS standard SNGA120412. A brazing material of an Ag alloy having a composition consisting of 30% by weight of Cu, 28% by weight of Zn, 2% by weight of Ni and 2% by weight of Ag is used for the brazing portion (corner portion) of the chip body made of a base cemented carbide. After performing brazing using an outer periphery to a predetermined size, the cutting edge portion is subjected to a honing process with a width of 0.15 mm and an angle of 25 °, and further subjected to finish polishing to obtain a chip shape of ISO standard SNGA120412. BN-based substrates AP were manufactured respectively.
[0015]
Next, each of the BN-based substrates A to P was ultrasonically cleaned in acetone and dried, and then dried in a radial direction from a central axis on a rotary table in an arc ion plating apparatus shown in FIG. It is placed on a multi-stage rotating support plate provided at predetermined distances along the outer periphery at a distance, and serves as a cathode electrode (evaporation source) on one side for forming the lowest Al content point having various component compositions. A Ti-Al-Si alloy and a Ti-Al-Si alloy for forming the highest content point of Al having various component compositions as a cathode electrode (evaporation source) on the other side are arranged to face each other with the rotary table interposed therebetween. The inside of the apparatus was heated to 430 ° C. with a heater while maintaining the vacuum at 0.5 Pa or less, and then Ar gas was introduced to form an atmosphere of 1.5 Pa Ar gas. A DC bias voltage of -1050 V is applied to the rotating BN base substrate, the surface of the BN base substrate is washed with Ar bombard, and nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 2 Pa. A DC bias voltage of -100 V is applied to the BN substrate rotating while rotating on the rotary table, and each of the cathode electrodes (the Ti-Al-Si alloy for forming the lowest Al content point and the Al highest content point is formed). A current of 100 A flows between the Ti-Al-Si alloy) and the anode electrode to generate an arc discharge, and thus the target composition shown in Tables 3 and 4 on the surface of the BN base along the layer thickness direction. The Al minimum content point and the Al maximum content point alternately and repeatedly exist at the target intervals shown in Tables 3 and 4, and the Al minimum content point and the Al minimum content point A hard coating layer having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the lowest Al content point to the highest Al content point, and also having the target layer thickness shown in Tables 3 and 4. Was formed by vapor deposition to produce each of the coated BN-based tools 1 to 16 of the present invention.
[0016]
For the purpose of comparison, the formation of the hard coating layer on the surfaces of the BN-based chip substrates A to P was carried out by using a normal arc ion plating apparatus shown in FIG. 2 as a cathode electrode (evaporation source). After mounting the Ti-Al alloy and the Ti-Al-Si alloy having the component compositions of, respectively, and evacuating the inside of the apparatus to maintain a vacuum of 0.5 Pa or less, the inside of the apparatus was heated to 500 ° C with a heater. Ar gas was introduced into the apparatus to form an Ar atmosphere of 5 Pa, and in this state, a BN base substrate was applied with a bias voltage of -800 V to clean the surface of the BN base substrate with Ar gas bombardment. Nitrogen gas was introduced to make a reaction atmosphere of 2 Pa, and the bias voltage applied to the BN substrate was reduced to -100 V to discharge an arc between the cathode electrode and the anode electrode. Is carried out under the conditions for generating the above-mentioned conventional BN-based tools having the target composition and the target layer thickness shown in Tables 5 and 6 on the surfaces of the BN-based substrates A to P, respectively. The (Ti, Al) N layer corresponding to the hard coating layer, that is, the (Ti, Al) N layer having substantially no composition change along the layer thickness direction, and also having the composition change substantially along the layer thickness direction. The comparative coated BN-based tools 1 to 16 were respectively manufactured under the same conditions as the manufacturing conditions of the coated BN-based tools 1 to 16 of the present invention described above, except that a hard coating layer composed of a (Ti, Al, Si) N layer was not formed. Manufactured.
[0017]
Next, with respect to the above-mentioned present invention coated BN base tools 1 to 16 and comparative coated BN base tools 1 to 16 in a state where they were screwed to the tip of a tool steel tool with a fixing jig,
Work material: JIS SCM415 carburized hardened round bar (surface hardness: HRC60),
Cutting speed: 300 m / min. ,
Notch: 0.3mm,
Feed: 0.07 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed high-cut cutting test of alloy steel under the following conditions:
Work material: JIS S15C induction hardened round bar (surface hardness: HRC55),
Cutting speed: 330 m / min. ,
Notch: 0.1mm,
Feed: 0.3 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed high-feed cutting test of carbon steel under the following conditions,
Work material: JIS FC300 round bar,
Cutting speed: 850 m / min. ,
Cut: 0.5mm,
Feed: 0.1 mm / rev. ,
Cutting time: 15 minutes,
A dry high-speed high-cut cutting test was performed on cast iron under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 2 to 5.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Table 3]

[0021]
[Table 4]

[0022]
[Table 5]

[0023]
The composition of the highest Al content and the lowest Al content in the hard coating layers constituting the resulting coated BN base tools 1 to 16 of the present invention, and the composition of the hard coating layers of the comparative coated BN base tools 1 to 16, When the contents of Ti, Al, and Si components were measured along the thickness direction using an Auger spectrometer, the hard coating layers of the coated BN base tools 1 to 16 of the present invention showed that the highest Al content point and the lowest Al content were obtained. And the content points are alternately and repeatedly present at substantially the same composition and interval as the target value, and from the Al maximum content point to the Al minimum content point, from the Al minimum content point to the Al maximum content point, Ti and Al It was confirmed that each component had a component concentration distribution structure in which the content ratio of each component continuously changed, and the average layer thickness of the hard coating layer also showed substantially the same value as the target layer thickness.
On the other hand, in the hard coating layers of the comparative coated BN base tools 1 to 16, no composition change is observed in the thickness direction, and the composition and the average layer thickness are substantially the same as the target composition and the target layer thickness. Was confirmed.
[0024]
【The invention's effect】
From the results shown in Tables 2 to 5, the hard coating layer has Al minimum content points and Al maximum content points alternately and repeatedly provided at predetermined intervals in the layer thickness direction, and the Al minimum content point and the Al minimum content point The coated BN-based tool of the present invention having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the content point and the Al minimum content point to the Al maximum content point, respectively, can be any of various steels and cast irons. The hard coating layer exhibits excellent chipping resistance even when the cutting process is performed at high speed with high heat generation and under heavy cutting conditions such as high cutting and high feed with high load. On the other hand, in the comparative coated BN base tool in which the hard coating layer is substantially composed of a (Ti, Al) N layer or a (Ti, Al, Si) N layer with no composition change along the layer thickness direction, The layer has high temperature hardness and resistance Although having sex, because not intended to comprise a sufficient high-temperature strength, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated BN-based tool of the present invention is excellent not only in cutting under normal conditions, but also particularly when cutting various kinds of steel and cast iron under high-speed heavy cutting conditions. Since it exhibits chipping resistance and exhibits excellent wear resistance over a long period of time, it can sufficiently cope with labor saving and energy saving of cutting work, and furthermore, cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used to form a hard coating layer constituting a coated BN-based tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a normal arc ion plating apparatus used for forming a hard coating layer constituting a comparative coated BN-based tool.

Claims (1)

A surface-coated cemented carbide obtained by physically depositing a hard coating layer made of a composite nitride of Ti, Al and Si on a surface of a substrate made of a cubic boron nitride-based sintered material with an average layer thickness of 0.5 to 10 μm. Cutting tools
The hard coating layer has an Al maximum content point and an Al minimum content point alternately and repeatedly provided at predetermined intervals along the layer thickness direction, and the Al maximum content point and the Al minimum content point, the Al From the lowest content point to the Al highest content point, the content ratios of Ti and Al each have a component concentration distribution structure that continuously changes,
Furthermore, the Al highest content point, composition _{formula: [Ti 1- (X + Z} ) Al X Si Z N] ( where in atomic ratio, X is 0.45 to 0.65, Z is from 0.01 to 0. 15),
The Al minimum content point, composition _{formula: [Ti 1- (Y + Z} ) Al Y Si Z N] ( where in atomic ratio, Y is 0.10 to 0.35, Z is a 0.01 to 0.15 Show),
Respectively, and the interval between the adjacent Al maximum content point and Al minimum content point is 0.01 to 0.1 μm,
A cutting tool made of a surface-coated cubic boron nitride-based sintered material having a hard coating layer exhibiting excellent chipping resistance by high-speed heavy cutting.

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