JP2004181555A - Surface-coated cermet cutting tool with hard coating layer excellent in thermal shock resistance and surface lubricatability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cermet cutting tool with hard coating layer excellent in thermal shock resistance. <P>SOLUTION: This surface-coated cermet cutting tool has a hard coating layer constituted of (a) to (c) on a surface of a tool base body constituted of WC group cemented carbide and TiCN group cermet: (a) A lower layer having average layer thickness of 3 to 20 μm, and constituted of a Ti compound layer constituted of lamination layers of one layer or more than two layers among a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer which are all evaporated and formed; (b) An upper layer having average layer thickness of 3 to 15 μm, constituted of an α type crystal structure of a crystal structure by applying heating transforming treatment to Al<SB>2</SB>O<SB>3</SB>having a κ type or θ type crystal structure in a state of being evaporated and formed, and also constituted of a heating transformed α type Al<SB>2</SB>O<SB>3</SB>layer having a structure of dispersing-distributing a heating transformed crack. (c) A surface layer having average layer thickness of 0.1 to 5 μm, and constituted of a Ti oxide layer for satisfying 1.2 to 1.9 in the atomic ratio of X to Ti by measuring a thickness directional central part by an Auger spectral analyzer when expressed by a composition formula : TiOx. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２１】
【表２】

【００２２】
【表３】

【００２３】
【表４】

【００２４】
【表５】

【００２５】
【表６】

【００２６】
【表７】

【００２７】
【発明の効果】
表５〜７に示される結果から、本発明被覆サーメット工具１〜１２は、硬質被覆層の上部層を構成する加熱変態α型Ａｌ₂Ｏ₃層中に分散分布する加熱変態生成クラックによるすぐれた熱衝撃吸収性および表面層のＴｉ酸化物層のもつ切粉に対するすぐれた表面潤滑性の作用で、熱衝撃がきわめて高く、かつ高い発熱を伴なうステンレス鋼や軟鋼の高速断続切削でも、切刃のチッピング発生が著しく抑制され、すぐれた耐摩耗性を発揮するのに対して、硬質被覆層の上部層が蒸着α型Ａｌ₂Ｏ₃層からなる従来被覆サーメット工具１〜１２においては、高速断続切削では前記蒸着α型Ａｌ₂Ｏ₃層が激しい熱衝撃に耐えられず、かつ被削材がステンレス鋼や軟鋼などのきわめて粘性が高く、かつ切粉が切刃表面に溶着し易い難削材であることと相俟って、切刃にチッピングが発生し、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、この発明の被覆サーメット工具は、通常の条件での連続切削や断続切削は勿論のこと、特に熱衝撃がきわめて高く、かつ高い発熱を伴なう切削条件の最も厳しい難削材の高速断続切削でもすぐれた耐チッピング性を示し、長期に亘ってすぐれた切削性能を発揮するものであるから、切削装置の高性能化並びに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】本発明被覆サーメット工具３の硬質被覆層を構成する加熱変態α型Ａｌ₂Ｏ₃層（目標層厚：１５μｍ）のＸ線回折チャートを示す図である。
【図２】本発明被覆サーメット工具７の硬質被覆層を構成する加熱変態α型Ａｌ₂Ｏ₃層（目標層厚：１０μｍ）のＸ線回折チャートを示す図である。
【図３】本発明被覆サーメット工具１１の硬質被覆層を構成する加熱変態α型Ａｌ₂Ｏ₃層（目標層厚：５μｍ）のＸ線回折チャートを示す図である。
【図４】従来被覆サーメット工具３の硬質被覆層を構成する蒸着α型Ａｌ₂Ｏ₃層（目標層厚：１５μｍ）のＸ線回折チャートを示す図である。
【図５】従来被覆サーメット工具７の硬質被覆層を構成する蒸着α型Ａｌ₂Ｏ₃層（目標層厚：１０μｍ）のＸ線回折チャートを示す図である。
【図６】従来被覆サーメット工具１１の硬質被覆層を構成する蒸着α型Ａｌ₂Ｏ₃層（目標層厚：５μｍ）のＸ線回折チャートを示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer that exhibits excellent thermal shock resistance to thermal shock repeatedly applied to the cutting edge at an extremely short pitch during high-speed interrupted cutting of steel, cast iron, etc., and more particularly, for stainless steel and mild steel. Even in high-speed interrupted cutting of difficult-to-cut materials that are extremely viscous and chips easily adhere to the cutting edge surface, the hard coating layer shows excellent surface lubricity against chips, so ordinary steel and cast iron Needless to say, when used for high-speed intermittent cutting of difficult-to-cut materials such as stainless steel and mild steel, surfaces that exhibit excellent cutting performance over a long period of time without chipping (small chipping) on the cutting edge The present invention relates to a coated cermet cutting tool (hereinafter, referred to as a coated cermet tool).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, generally, a substrate (hereinafter, these are collectively referred to as a tool substrate) formed of a tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or a titanium cermet (hereinafter, referred to as TiCN) -based cermet is generally provided on a surface of the substrate. ,
(A) As a lower layer, a layer of Ti carbide (hereinafter referred to as TiC) having an average layer thickness of 3 to 20 μm, all of which are formed by chemical vapor deposition and / or physical vapor deposition (hereinafter simply referred to as vapor deposition). , A nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbonate (hereinafter referred to as TiCO) layer, and a carbonitride (hereinafter referred to as TiCNO) layer A Ti compound layer composed of one or two or more layers,
(B) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having an average layer thickness of 3 to 15 μm and having an α-type and / or κ-type crystal structure as an upper layer;
A coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool can be used for continuous cutting or intermittent cutting of various types of steel or cast iron, for example. It is also known that it is used (for example, see Patent Document 1).
[0003]
In general, the Ti compound layer and the Al ₂ O ₃ layer constituting the hard coating layer of the above-mentioned coated cermet tool have a granular crystal structure, and further, the TiCN layer constituting the Ti compound layer is provided with the strength of the layer itself. For the purpose of improvement, using a mixed gas containing an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus, a chemical vapor deposition is performed at a medium temperature range of 700 to 950 ° C. to form a vertically grown crystal structure. It is also known to have it (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-6-31503 [Patent Document 2]
JP-A-6-8010 [0005]
[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 has been a strong demand for labor saving, energy saving, and further cost reduction for cutting work.Accordingly, cutting work has tended to be further accelerated. In the case of coated cermet tools, there is no problem if this is used for continuous cutting or interrupted cutting under ordinary conditions such as steel or cast iron. When used for high-speed interrupted cutting, in which thermal shock is repeatedly applied at a very short pitch, the upper layer of the hard coating layer, the Al ₂ O ₃ layer, is hard and has excellent heat resistance, but is brittle to thermal shock. In addition, chipping (small chipping) easily occurs in the hard coating layer, and in high-speed interrupted cutting of work materials such as stainless steel and mild steel having extremely high viscosity, the chips of these work materials are hard coated layer. Because of the high affinity for the particular the Al ₂ O ₃ layer constituting, easily welded to the cutting edge surface, I the welding behavior the repeated thermal shock phenomenon coupled with the liable further chipping occurs in the cutting edge As a result, at present, the service life is reached in a relatively short time.
[0006]
[Means for Solving the Problems]
In view of the above, the inventors of the present invention have proposed cutting, even in high-speed intermittent cutting of difficult-to-cut materials such as the above-mentioned stainless steel and mild steel, which are extremely viscous and in which cutting chips easily adhere to the cutting blade surface. As a result of conducting research to develop a coated cermet tool with excellent chipping resistance,
After forming the Ti compound layer as a lower layer on the surface of the tool base under ordinary conditions, an Al ₂ O ₃ layer having a κ-type or θ-type crystal structure is formed by vapor deposition under the same general conditions. When heat treatment is performed in this state, preferably in an Ar atmosphere at a temperature of 1000 ° C. or higher and maintained for a predetermined time, the κ-type or θ-type crystal structure is transformed into an α-type crystal structure, and the heat transformation is performed. The generated cracks have a structure dispersed and distributed in the layer, and the resulting heat-transformed α-type Al ₂ O ₃ layer is used as an upper layer, and the surface of this upper layer is
The reaction gas composition, by volume%,
TiCl _4: 0.2~10%,
CO ₂ : 0.1 to 10%,
Ar: 5 to 60%,
H ₂ : rest,
And
Reaction atmosphere temperature: 800 to 1100 ° C,
Reaction atmosphere pressure: 4 to 70 kPa (30 to 525 torr),
Under the conditions described above, the layer has an average layer thickness of 0.1 to 5 μm, and the center in the thickness direction is measured by an Auger spectroscopic analyzer, and the ratio of oxygen to Ti is 1.2 to 1. 9, that is,
Composition formula: TiO _x ,
When represented by
X: 1.2 to 1.9 in atomic ratio to Ti;
Is formed as a surface layer by evaporation, the Ti oxide layer sufficiently penetrates into the heat transformation generation crack at the interface with the heat transformation α-type Al ₂ O ₃ layer, and In addition to maintaining the transformation-generated cracks in a significantly stabilized state, it has a very low affinity for highly viscous and difficult-to-cut materials such as stainless steel and mild steel, which has the same properties as high-speed cutting with high heat generation. Therefore, in the coated cermet tool in which the lower layer of the hard coating layer is composed of the Ti compound layer, and the upper layer and the surface layer are composed of the above-mentioned heat-transformed α-type Al ₂ O ₃ layer and the Ti oxide layer. , the heating transformation α-type Al ₂ O ₃ heat transformation product cracks disperse distribution in the layer constituting the upper layer, in particular absorb severe thermal shock during high-speed intermittent cutting, and alleviate this, further Since the Ti oxide layer of the surface layer has a property that chips are not easily welded, that is, it has excellent surface lubricating properties, a research result was obtained that the occurrence of chipping in the hard coating layer was significantly suppressed. .
[0007]
The present invention has been made on the basis of the above research results, and has a tool base formed of a WC-based cemented carbide or a TiCN-based cermet,
(A) The lower layer has an average layer thickness of 3 to 20 μm, and is a stack of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, all of which are formed by vapor deposition. A Ti compound layer comprising:
(B) As an upper layer, Al ₂ O ₃ having an average layer thickness of 3 to 15 μm and having a κ-type or θ-type crystal structure in a vapor-deposited state is subjected to a heat transformation treatment to change the crystal structure to an α-type crystal. A heating transformation α-type Al ₂ O ₃ layer having a structure and a structure in which heating transformation generation cracks are dispersed and distributed,
(C) the surface layer has an average layer thickness of 0.1 to 5 μm, and
Composition formula: TiO _x ,
When represented by, the center in the thickness direction is measured with an Auger spectrometer,
X: 1.2 to 1.9 in atomic ratio to Ti;
A Ti oxide layer that satisfies
The present invention is characterized by a coated cermet tool having a hard coating layer formed of the above (a) to (c) and having excellent thermal shock resistance and surface lubricity.
[0008]
Next, the reason why the average thickness of the constituent layers of the hard coating layer of the coated cermet tool of the present invention is limited as described above will be described.
(A) Lower layer (Ti compound layer)
The Ti compound layer itself has strength, and the presence of the Ti compound layer allows the hard coating layer to have strength. In addition, the Ti compound layer is firmly attached to both the tool base and the heating-transformed α-type Al ₂ O ₃ layer as the upper layer. Has a function of contributing to the improvement of the adhesion of the hard coating layer to the tool base, but if the average layer thickness is less than 3 μm, the above effect cannot be sufficiently exerted. If it exceeds 20 μm, it becomes easy to cause thermoplastic deformation especially in high-speed interrupted cutting accompanied by high heat generation, which causes uneven wear. Therefore, the average layer thickness is set to 3 to 20 μm.
[0009]
(B) Upper layer (heat-transformed α-type Al ₂ O ₃ layer)
The heat-transformed α-type Al ₂ O ₃ layer enhances the wear resistance of the hard coating layer due to the high hardness and excellent heat resistance of the Al ₂ O ₃ itself, as well as the heat transformation dispersed and distributed in the layer as described above. The effect of the generated cracks absorbs the thermal shock and has the effect of significantly suppressing the occurrence of chipping in the hard coating layer. However, if the average layer thickness is less than 3 μm, the above effect cannot be sufficiently exerted. On the other hand, if the average layer thickness exceeds 15 μm and becomes too thick, the cracks generated by the heat transformation may cause chipping. Therefore, the average layer thickness is set to 3 to 15 μm.
[0010]
(C) Surface layer (Ti oxide layer)
As described above, the Ti oxide layer penetrates sufficiently into the heat transformation-generated cracks at the interface with the heat-transformed α-type Al ₂ O ₃ layer to maintain the heat-transformed cracks in a significantly stabilized state. In addition to having the effect of sufficiently exhibiting the improvement in thermal shock resistance brought about by the above-mentioned heat-transformed α-type Al ₂ O ₃ layer, it also has excellent surface lubricity, but if the average layer thickness is less than 0.1 μm, The stabilization of the heat transformation generation cracks in the heat transformation α-type Al ₂ O ₃ layer is not only insufficient, but the desired surface lubricity cannot be secured, so that chipping is likely to occur, On the other hand, the effect of the Ti oxide layer is sufficient when the average layer thickness is up to 5 μm, and the average layer thickness is determined to be 0.1 to 5 μm in consideration of economy.
[0011]
In the coated cermet tool of the present invention, the atomic ratio (X value) of oxygen (O) to Ti in the Ti oxide layer constituting the surface layer is set to 1.2 to 1.9, because the value is 1 to 1. If it is less than 0.2, the desired excellent surface lubricating property cannot be secured, while if it exceeds 1.9, pores are easily formed in the layer, and it is difficult to form a sound surface layer stably. It is because it becomes.
[0012]
Further, when the Ti oxide layer constituting the hard coating layer of the coated cermet tool of the present invention was observed by X-ray diffraction, Ti ₂ O ₃ and Ti ₃ O ₅ were obtained in accordance with the X value of the composition formula: TiO _X. , Ti ₄ O ₇ , and Ti ₅ O ₉ show a diffraction pattern in which a main peak appears in at least one of them. From these diffraction results, the Ti oxide layer is composed of a material called a Magneli phase. it is clear that those represented by Ti _n O _2n-1.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cermet tool of the present invention will be specifically described with reference to examples.
As raw material powders, WC powder, TiC powder both having an average particle size of 1 to 3 [mu] m, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, prepared TaN powder and Co powder, Then, these raw material powders were blended into the blending composition shown in Table 1, further added with wax, ball-milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a green compact of a predetermined shape at a pressure of 98 MPa. Then, this green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is honed with R: 0.07 mm. By processing, tool bases A to F made of a WC-based cemented carbide having a throw-away tip shape specified in ISO-CNMG120408 were manufactured, respectively.
[0014]
Further, as the raw material powder, both the average particle (TiC / TiN = 50/50 in mass ratio) TiCN having a diameter of 0.5~2μm powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder , Co powder, and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and pressed into a green compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge was subjected to a honing process of R: 0.07 mm to obtain an ISO. Tool bases a to f made of TiCN-based cermet having a chip shape of standard CNMG120412 were formed.
[0015]
Then, on the surfaces of the tool bases A to F and the tool bases a to f, a conventional chemical vapor deposition apparatus was used, and Table 3 (l-TiCN in Table 3 is a vertically long sheet described in JP-A-6-8010). It shows the conditions for forming a TiCN layer having a growth crystal structure, and the other conditions show the conditions for forming a normal granular crystal structure.) A compound layer is formed by vapor deposition as a lower layer of the hard coating layer, and then a κ-type or θ-type Al ₂ O ₃ layer is formed by vapor deposition under the same conditions as shown in Table 3, and the layer is formed in an Ar atmosphere at a temperature of: A heat transformation treatment is performed at a temperature of 1050 ° C. for a predetermined time within a range of 2 to 10 hours to transform the κ-type or θ-type crystal structure into an α-type. Table 5 also shows the distribution of the heated transformation α-type Al ₂ O ₃ layer. By forming the Ti oxide layer as the upper layer of the hard coating layer with the target layer thickness shown in FIG. Inventive coated cermet tools 1 to 12 were manufactured respectively.
For the purpose of comparison, as shown in Table 6, except that the upper layer of the hard coating layer was a vapor-deposited α-type Al ₂ O ₃ layer having an average layer thickness also shown in Table 6, and the surface layer was not formed. Manufactured the conventional coated cermet tools 1 to 12 under the same conditions.
[0016]
Further, X-ray diffraction was performed for the purpose of observing the difference between the heat-transformed α-type Al ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool of the present invention and the conventional coated cermet tool. It was measured.
In the measurement of these X-ray diffractions, a single crystal WC having diffraction peaks only on the (001) plane and the (002) plane on the X-ray diffraction chart was used as a substrate sample, and the surface of the substrate sample was coated with the coated cermet of the present invention. Heat-transformed α-type Al ₂ O ₃ layers having a target layer thickness of 15 μm, 10 μm, and 5 μm for tools 3, 7, and 11, and the same target layer thickness for conventional coated cermet tools 3, 7, and 11 also having a target layer thickness of 15 μm, 10 μm, Under the same conditions as the formation conditions of the deposited α-type Al ₂ O ₃ layer of 5 μm and 5 μm, respectively, and the heat-transformed α-type Al ₂ O ₃ layer and the deposited α-type Al ₂ O ₃ layer having the target layer thicknesses of 15 μm, 10 μm and 5 μm, respectively. Are directly formed to produce coating samples A to C of the present invention and conventional coating samples a to c. X-ray diffraction of the above-mentioned heat-transformed α-type Al ₂ O ₃ layer and vapor-deposited α-type Al ₂ O ₃ layer of these coated samples By measuring Carried out was. The measurement results are shown in FIGS.
FIGS. 1 to 3 show X-ray diffraction charts of the heat-transformed α-type Al ₂ O ₃ layers of coating samples A to C of the present invention, and X-ray diffraction charts of vapor-deposited α-type Al ₂ O ₃ layers of conventional coating samples a to c. 4 to 6, the heating-transformed α-type Al ₂ O ₃ layer shows clear diffraction peaks on the (006) plane and the (018) plane, whereas the vapor-deposited α-type Al ₂ It is clear that the (006) plane and the (018) plane have no diffraction peak in the O ₃ layer.
Further, a heat-transformed α-type Al ₂ O ₃ layer and a vapor-deposited α-type Al ₂ O ₃ layer having target layer thicknesses of 15 μm, 10 μm, and 5 μm, respectively, are directly formed on the surface of the substrate sample composed of the single crystal WC. For each of the heat-transformed α-type Al ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer of the coated samples A to C of the present invention and the conventionally coated samples a to c, Electron beam backscatter diffraction (EBSD) of the crystal plane was performed using a thermal field emission scanning electron microscope (manufactured by JEOL Ltd.) and an azimuthal diffractometer (manufactured by Texem Laboratories, Inc.). In each of the heat-transformed α-type Al ₂ O ₃ layers, the crystal orientation map shows a dark red color tone, which is due to the hexagonal (0001) plane (hexagonal parallel plane), which is the crystal structure of Al ₂ O _3. wherein the Al ₂ O ₃ layer surface (substrate trial It indicates that the oriented parallel to very strong relative to the surface), whereas said at deposition α-type Al ₂ O ₃ layer is either green or blue crystal orientation map, appear more yellow and pink and various shades This indicates that there is no specific orientation in the crystal plane constituting the hexagonal crystal.
[0017]
Further, with respect to the coated cermet tools 1 to 12 of the present invention and the conventional coated cermet tools 1 to 12 obtained as a result, the constituent layers of the hard coating layer were observed using a scanning electron microscope (observing the longitudinal section of the layers). As a result, the former consisted of a Ti compound layer, a heat-transformed α-type Al ₂ O ₃ layer in which cracks generated by heat transformation were dispersed and distributed in the layer, and a Ti oxide layer. It was confirmed that the layer consisted of a mold Al ₂ O ₃ layer.
Further, the surface layer of the coated cermet tools 1 to 12 of the present invention was measured for the oxygen content ratio (X value) at the center in the thickness direction using an Auger spectrometer, and the target values shown in Table 4 were obtained. And showed substantially the same value.
In addition, when the thicknesses of the constituent layers of the hard coating layer of these coated cermet tools were measured using a scanning electron microscope (also in the longitudinal section), the average layer thickness was substantially the same as the target layer thickness. (Average value of five-point measurements).
[0018]
Next, the above coated cermet tools 1 to 6 of the present invention and the conventional coated cermet tools 1 to 6 in a state where each of the above various coated cermet tools was screwed to the tip of a tool steel tool with a fixing jig, ,
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / SUS304,
Cutting speed: 400m / min,
Cut: 1.0 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of stainless steel under the conditions of
Work material: JIS S15C lengthwise round bar
Cutting speed: 450m / min,
Cut: 1.5 mm,
Feed: 0.2 mm / rev,
Cutting time: 3 minutes,
A dry high-speed interrupted cutting test of mild steel was performed under the following conditions.
[0019]
Further, for the coated cermet tools 7 to 12 of the present invention and the conventional coated cermet tools 7 to 12,
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / SUS304,
Cutting speed: 400m / min,
Cut: 0.5mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of stainless steel under the conditions of
Work material: JIS S15C lengthwise round bar
Cutting speed: 450m / min,
Cut: 1.0 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
A dry high-speed intermittent cutting test was performed on mild steel under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. Table 7 shows the measurement results.
[0020]
[Table 1]

[0021]
[Table 2]

[0022]
[Table 3]

[0023]
[Table 4]

[0024]
[Table 5]

[0025]
[Table 6]

[0026]
[Table 7]

[0027]
【The invention's effect】
From the results shown in Tables 5 to 7, the coated cermet tools 1 to 12 of the present invention were excellent due to the heat transformation generated cracks dispersed and distributed in the heat transformation α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. The effect of thermal shock absorption and excellent surface lubricity on the chips of the Ti oxide layer on the surface layer makes it possible to cut even high-speed interrupted cutting of stainless steel and mild steel with extremely high thermal shock and high heat generation. While the occurrence of chipping of the blade is remarkably suppressed and excellent wear resistance is exhibited, the conventional coated cermet tools 1 to 12 in which the upper layer of the hard coating layer is formed of a vapor-deposited α-type Al ₂ O ₃ layer have a high speed. In intermittent cutting, the vapor deposited α-type Al ₂ O ₃ layer cannot withstand severe thermal shock, the work material is extremely viscous, such as stainless steel or mild steel, and cutting chips are easily welded to the cutting surface. Phase with being wood I, chipping occurs in the cutting edge, it is clear that lead to a relatively short time service life.
As described above, the coated cermet tool of the present invention can be used not only for continuous cutting and interrupted cutting under normal conditions, but also for particularly difficult cutting materials with extremely high thermal shock and cutting conditions accompanied by high heat generation. It shows excellent chipping resistance even in high-speed interrupted cutting, and exhibits excellent cutting performance over a long period of time. It can be satisfied enough.
[Brief description of the drawings]
FIG. 1 is a diagram showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 15 μm) constituting a hard coating layer of a coated cermet tool 3 of the present invention.
FIG. 2 is an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 10 μm) constituting a hard coating layer of the coated cermet tool 7 of the present invention.
FIG. 3 is a view showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 5 μm) constituting a hard coating layer of the coated cermet tool 11 of the present invention.
FIG. 4 is a diagram showing an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 15 μm) constituting a hard coating layer of the conventional coated cermet tool 3.
FIG. 5 is a diagram showing an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 10 μm) constituting a hard coating layer of the conventional coated cermet tool 7.
FIG. 6 is a diagram showing an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 5 μm) constituting a hard coating layer of the conventional coated cermet tool 11.

Claims (1)

On the surface of a tool substrate composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) As a lower layer, it has an average layer thickness of 3 to 20 μm, and is formed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, all of which are formed by evaporation. A Ti compound layer composed of one or two or more layers of
(B) As an upper layer, aluminum oxide having an average layer thickness of 3 to 15 μm and having a κ-type or θ-type crystal structure in a vapor-deposited state is subjected to a heat transformation treatment to change the crystal structure to an α-type crystal structure. Heat transformation α-type aluminum oxide layer having a structure in which heat transformation generated cracks are dispersed and distributed,
(C) the surface layer has an average layer thickness of 0.1 to 5 μm, and
Composition formula: TiO _x ,
When represented by, the center in the thickness direction is measured with an Auger spectrometer,
X: an atomic ratio to Ti of 1.2 to 1.9,
A Ti oxide layer that satisfies
A cutting tool made of a surface-coated cermet having a hard coating layer having excellent thermal shock resistance and surface lubricity, which is formed by forming the hard coating layer composed of (a) to (c) above.

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