JP4720990B2 - Surface-coated cemented carbide cutting tool with excellent wear resistance due to high-speed gear cutting of highly reactive work materials - Google Patents

Description

  This invention is particularly suitable for high-speed gear cutting with high heat generation of highly reactive work materials such as Ti alloys, high Si-containing Al alloys, and stainless steel, and the hard coating layer is highly reactive. Surface-coated cemented carbide cutting tool (hereinafter referred to as coated carbide cutting tool) that exhibits extremely low reactivity to the workable material and as a result, exhibits excellent wear resistance over a long period of time. ).

Conventionally, various gears are generally used as structural members for automobiles, aircrafts, and various drive devices, and coated carbide gear cutting tools (solid hobs) are used for gear cutting of gear teeth.
Further, as the coated carbide gear cutting tool, for example, as shown in a schematic perspective view in FIG. 3, a plurality of tooth grooves are formed radially with respect to the rotation axis and along the length direction. Between the front and rear surfaces that face the tooth gap and the front surface is a rake face with respect to the rotation direction, and the tooth is composed of a top surface (tooth tip tooth surface) and both side surfaces (left and right tooth surfaces) that are flank surfaces Various hard parts are formed on the surface of a tungsten carbide based cemented carbide cutting tool body (hereinafter referred to as a carbide cutting base) machined into a shape in which a plurality of parts are continuously formed along the length direction. A coated carbide gear cutting tool formed by physical vapor deposition of a coating layer is known.

On the other hand, as a hard coating layer of a cutting tool made of a surface-coated cemented carbide such as a normal throwaway tip, end mill, and drill, for example,
_{Formula: [Ti 1- (X + Y} ) Al X Ta Y] N ( provided that an atomic ratio, X is from .50 to 0.65, Y represents a 0.01 to 0.09),
It is known that a hard coating layer composed of a composite nitride of Ti, Al, and Ta [hereinafter referred to as (Ti, Al, Ta) N] satisfying the above conditions is vapor-deposited with an average layer thickness of 2 to 8 μm. The (Ti, Al, Ta) N layer has high-temperature hardness and heat resistance due to Al as a constituent component, high-temperature strength is improved due to the Ti, and further, the Ta inhibits reactivity with the work material. It is also known that will be demonstrated.

Furthermore, the above-mentioned coated carbide cutting tool provided with the above-mentioned hard coating layer is obtained by, for example, applying the above-mentioned carbide cutting base to an arc ion plating apparatus which is a kind of physical vapor deposition apparatus schematically shown in FIG. For example, between the anode electrode and a cathode electrode (evaporation source) in which a Ti—Al—Ta alloy having a predetermined composition is set in a state where the inside of the apparatus is heated to a temperature of, for example, 500 ° C. with a heater. Arc discharge was generated under the condition of current: 90 A, and simultaneously nitrogen gas was introduced into the apparatus as a reaction gas to form a reaction atmosphere of, for example, 2 Pa. On the other hand, a bias voltage of, for example, −100 V was applied to the substrate. It is also known that it is produced by vapor-depositing a hard coating layer comprising the (Ti, Al, Ta) N layer on the surface of the substrate.
Japanese Patent No. 3351054

  In recent years, the performance of cutting devices has been dramatically improved, while there is a strong demand for labor saving and energy saving and further cost reduction for cutting. In coated carbide gear cutting tools, when used for gear cutting of carbon steel, low alloy steel, and ordinary cast iron, there is no problem with normal gear cutting performance. When using gear cutting of highly reactive work materials such as Si-containing Al alloys and stainless steel under high speed gear cutting conditions with high heat generation, especially hard coating layers Combined with the fact that the reaction with the highly reactive work material is promoted as a result of the generation of high heat, the reaction proceeds rapidly, and as a result, the wear life is reached in a relatively short time. is there.

Therefore, in order to develop a coated carbide tool exhibiting excellent wear resistance with a hard coating layer particularly in high-speed gear cutting of the highly reactive work material from the above viewpoint, As a result of conducting research by paying attention to the (Ti, Al, Ta) N layer constituting the hard coating layer of the above conventional coated carbide gear cutting tool,
(A) In the (Ti, Al, Ta) N layer constituting the hard coating layer, the reactivity with the highly reactive work material decreases as the content ratio of the Ta component increases. In the conventional (Ti, Al, Ta) N layer, the Ta content ratio of about 1 to 9 atomic% can satisfactorily suppress the reaction with the highly reactive work material by high-speed gear cutting with high heat generation. In order to sufficiently suppress the reaction with the highly reactive work material by high-speed gear cutting, it is necessary to contain 50 to 70 atomic% of Ta, far exceeding the above 1 to 9 atomic%, In order to practically use a (Ti, Al, Ta) N layer containing 50 to 70 atomic% Ta component as a hard coating layer, it is necessary to contain a predetermined amount of Ti to ensure a predetermined high temperature strength. In this case, the content ratio of the Al component is unavoidably low. Results hot hardness and shall become that heat resistance of very low.

(B) Composition formula: (Ti _{1− (A + B)} Al _A Ta _B ) N (provided that atomic ratio is 0.01 to 0.10 and B is 0.50 to 0.70) A (Ti, Al, Ta) N layer having a Ta content ratio of 50 to 70 atomic%;
Composition formula: (Ti _{1− (C + D)} Al _C Ta _D ) N (wherein, C is 0.30 to 0.45 and D is 0.20 to 0.35 in atomic ratio), relative In particular, the content ratio of the Al component is increased, while the content ratio of the Ta component is relatively lowered in order to ensure a high temperature strength by containing a predetermined amount of the Ti component (Ti, Al, Ta) N layer,
Are alternately laminated in a state where each layer has an average layer thickness of 5 to 20 nm (nanometers), and the resulting (Ti, Al, Ta) N layer has a thin layer of alternately laminated structure, The above-described high Ta content (Ti, Al, Ta) N layer (hereinafter referred to as the thin layer A) has an excellent work material reactivity suppressing effect, and a Ta content ratio relative to the thin layer A. And a relatively high high temperature hardness and heat resistance of the (Ti, Al, Ta) N layer (hereinafter referred to as thin layer B) with a low Al content and a high Al content. Be ready for practical use as a layer.

(C) The (Ti, Al, Ta) N layer having the alternate layered structure of the thin layer A and the thin layer B of (b) above is required for high-speed gear cutting of a highly reactive work material. Although it has a material reactivity inhibiting effect, it does not have a sufficiently satisfactory high temperature hardness and heat resistance, so this is provided as the upper layer of the hard coating layer, while the same as the lower layer, the work material reactivity inhibiting effect is (Ti, Al, Ta) N layer having a composition corresponding to the above-mentioned conventional hard coating layer, which is insufficient but has a relatively high content of Al component and has excellent high temperature hardness and heat resistance, ,
Compositional formula: [Ti _{1− (E + F)} Al _E Ta _F ] N (wherein E is 0.50 to 0.65 and F is 0.01 to 0.09 in terms of atomic ratio) (Ti, Al, Ta) N layer of single phase structure,
The resulting hard coating layer has a high temperature hardness, heat resistance, and high temperature strength in addition to the excellent work material reactivity suppression effect. The coated carbide gear cutting tool formed by vapor deposition of the above-mentioned high-reactive work material with high heat generation, the reactive wear between the high-reactive work material and the hard coating layer is remarkable. Since gear cutting is performed in a restrained state, chipping will not occur and excellent wear resistance will be exhibited over a long period of time.
The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above research results, and a plurality of tooth spaces are formed radially and along the length direction with respect to the rotation axis. The tooth part that consists of the front and rear faces that face the groove and the front face is a rake face with respect to the rotation direction, and the top face (tooth tip tooth face) and both side faces (left and right tooth faces) that are flank faces On the surface of the tungsten carbide based cemented carbide cutting tool base having a shape formed continuously along the direction,
(A) Both are composed of an upper layer and a lower layer made of (Ti, Al, Ta) N, the upper layer has a layer thickness of 0.5 to 1.5 μm, and the lower layer has a layer thickness of 2 to 6 μm. ,
(B) Each of the upper layers has an alternate laminated structure of thin layers A and B having a layer thickness of 5 to 20 nm (nanometer),
The thin layer A is
_{Formula: [Ti 1- (A + B} ) Al A Ta B] N ( provided that an atomic ratio, A is 0.01 to 0.10, B represents a 0.50 to 0.70) satisfies (Ti , Al, Ta) N layer,
The thin layer B is
_{Formula: [Ti 1- (C + D} ) Al C Ta D] N ( provided that an atomic ratio, C is 0.30 to 0.45, D represents a 0.20 to 0.35) satisfies (Ti , Al, Ta) N layer,
(C) the lower layer has a single phase structure;
Composition formula: [Ti _{1− (E + F)} Al _E Ta _F ] N (wherein E is 0.50 to 0.65 and F is 0.01 to 0.09 in atomic ratio) (Ti , Al, Ta) N layer,
Coated cemented carbide cutting tool (surface coated cemented carbide alloy tooth) that exhibits excellent wear resistance due to high-speed gear cutting of highly reactive work materials. Cutting tool).

Next, regarding the hard coating layer of the coated carbide gear cutting tool of the present invention, the reason why the numerical values are limited as described above will be described.
(A) Composition formula and layer thickness of the lower layer As described above, the Al component in the (Ti, Al, Ta) N layer constituting the hard coating layer improves high-temperature hardness and heat resistance, while the Ti component Has the effect of significantly reducing the reactivity with the work material, especially the Ta component, and in the lower layer, the overall content of the Al component is increased in the lower layer to achieve high high temperature hardness and heat resistance. Although the E value indicating the Al content ratio is less than 0.50 in terms of the total amount of Ti and Ta (atomic ratio, the same shall apply hereinafter), the ratio of Ti is relatively high, and the high-speed teeth The excellent high-temperature hardness and heat resistance required for cutting cannot be ensured, and the progress of wear is rapidly accelerated. On the other hand, when the E value indicating the Al ratio exceeds 0.65, The ratio of Ti is relatively low, and the high temperature strength is abrupt. As a result, chipping (slight chipping) or the like is likely to occur, so the E value was set to 0.50 to 0.65.
Further, the F value indicating the proportion of Ta is a proportion of the total amount of Ti and Al, and if it is less than 0.01, a predetermined work material reactivity suppression effect cannot be ensured, while the F value is If it exceeds 0.09, the high-temperature strength suddenly decreases, so the F value was determined to be 0.01 to 0.09.
Furthermore, if the layer thickness is less than 2 μm, the excellent high-temperature hardness and heat resistance cannot be imparted to the hard coating layer over a long period of time, resulting in a short tool life, while if the layer thickness exceeds 6 μm Since the chipping is likely to occur, the layer thickness is set to 2 to 6 μm.

(B) Composition formula of upper layer thin layer A As described above, the Ta component in (Ti, Al, Ta) N of the upper layer thin layer A is made as high as possible to suppress the reactivity of the work material. It is included for the purpose of further improving the effect and reducing reactive wear in high-speed gear cutting of high-reactive work materials with high heat generation. Therefore, when the B value is less than 0.50, the desired excellent The effect of suppressing the reactivity of the work material cannot be ensured. On the other hand, when the B value exceeds 0.70, the content ratio of the Ti component becomes relatively small, and the high temperature strength that the layer itself should have is ensured. Therefore, the B value was set to 0.50 to 0.70.
In addition, the A value indicating the proportion of Al is the proportion of the total amount of Ti and Ta, and if it is less than 0.01, the minimum high-temperature hardness and heat resistance cannot be ensured, leading to accelerated wear. On the other hand, if the A value exceeds 0.10, the high-temperature strength decreases, causing chipping. Therefore, the A value was set to 0.01 to 0.10.

(C) Composition formula of thin layer B of the upper layer In the thin layer B of the upper layer, the content ratio of the Ta component is relatively lower than that of the thin layer A, and the content ratio of the Al component is relatively By keeping the thin layer A high, the thin layer A has insufficient high-temperature hardness and heat resistance, reinforces the high-temperature hardness and heat resistance shortage of the adjacent thin layer A, and thus has the excellent thin layer A. The upper layer having a relatively high high temperature hardness and heat resistance of the thin layer B is formed, and the C value indicating the Al content ratio in the composition formula If the C value is less than 0.30, the predetermined high temperature hardness and heat resistance cannot be ensured, and wear progresses. On the other hand, if the C value exceeds 0.45, the high temperature of the entire upper layer is increased. Decrease in strength is inevitable and causes chipping. It was defined as 0.30 to 0.45.
Further, the D value indicating the ratio of Ta is a ratio of the total amount of Ti and Al. If the D value is less than 0.20, a decrease in the work material reactivity suppression effect of the entire upper layer is unavoidable, whereas the same D value When the value exceeds 0.35, the high-temperature strength of the entire upper layer suddenly decreases, so the D value was set to 0.20 to 0.35.

(D) Layer thicknesses of upper layer thin layer A and layer B If each layer thickness is less than 5 nm, it is difficult to form each thin layer clearly with the above composition. It is not possible to ensure excellent work material reactivity suppressing effect, and also to ensure a predetermined high temperature hardness and heat resistance, and if each layer thickness exceeds 20 nm, each thin layer has a defect, that is, thin layer A. Insufficient high temperature hardness and heat resistance, and thin layer B, the lack of work material reactivity suppression effect appears locally in the layer, which makes it easier for chipping to occur and promotes the progress of wear. Therefore, the thickness of each layer was set to 5 to 20 nm.

(E) Layer thickness of the upper layer If the layer thickness is less than 0.5 μm, it is not possible to provide the hard coating layer with long-term hardness and heat resistance, which is excellent in its own workability, and to the hard coating layer over a long period of time. The tool life is short-lived. On the other hand, if the layer thickness exceeds 1.5 μm, chipping tends to occur. Therefore, the layer thickness is set to 0.5 to 1.5 μm.

  In the coated carbide gear cutting tool of the present invention, the hard coating layer is composed of a (Ti, Al, Ta) N layer, and the upper layer of the hard coating layer is formed by alternately laminating a thin layer A and a thin layer B. Because it has excellent work material reactivity suppressing effect while maintaining the predetermined high temperature hardness and heat resistance, the lower layer of the same single phase structure has relatively high temperature hardness and heat resistance. In particular, even in high-speed gear cutting with high heat generation of highly reactive work materials such as Ti alloy, high Si content Al alloy, and stainless steel, the reactive wear of the hard coating layer is significantly suppressed. It exhibits excellent wear resistance over a long period of time.

Next, the coated carbide gear cutting tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders are blended in the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. Medium, sintered at 1400 ° C. for 1 hour to form a cemented carbide round bar material of diameter: 85 mm × length: 125 mm, and machined from this material, outer diameter: 80 mm X Length: Solid hob type cemented carbide cutting bases A to J shown in FIG. 3 each having a total dimension of 120 mm and a shape of two right-hand twists x 16 grooves were manufactured.

(A) Next, each of the above-mentioned superhard gear cutting bases A to J is ultrasonically cleaned in acetone and dried, and the central axis on the rotary table in the arc ion plating apparatus shown in FIG. A thin layer of an upper layer having a component composition corresponding to the target composition shown in Table 2 as a cathode electrode (evaporation source) on one side, mounted along a peripheral portion at a predetermined distance in the radial direction from Ti-Al-Ta alloy for forming A, and Ti-Al- for forming thin layer B of the upper layer having the component composition corresponding to the target composition shown in Table 2 as the cathode electrode (evaporation source) on the other side A Ta alloy is disposed opposite to the rotary table, and Ti-Al- for forming a lower layer as a cathode electrode (evaporation source) along the rotary table at a position shifted by 90 degrees from both the Ti-Al-Ta alloys. Ta The gold is attached,
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the interior of the apparatus is heated to 500 ° C. with a heater, and then rotated onto the rotating table while rotating on the rotating table. A DC bias voltage of −1000 V is applied, and a current of 100 A is passed between the lower layer forming Ti—Al—Ta alloy and the anode electrode to generate an arc discharge. Bombard cleaning with Ti-Al-Ta alloy,
(C) Introducing nitrogen gas as a reaction gas into the apparatus to make a reaction atmosphere of 3 Pa, applying a DC bias voltage of −100 V to the carbide cutting base rotating while rotating on the rotary table, and An arc discharge is generated by flowing a current of 100 A between the Ti—Al—Ta alloy for forming the lower layer and the anode electrode, so that the target composition and target shown in Table 2 are formed on the surface of the cemented carbide cutting base. (Ti, Al, Ta) N layer having a single-phase structure of layer thickness is deposited as a lower layer of the hard coating layer,
(D) Next, nitrogen gas was introduced as a reaction gas into the apparatus to make a reaction atmosphere of 2 Pa, and a DC bias voltage of −100 V was applied to the carbide cutting base rotating while rotating on the rotary table. In this state, a predetermined current in the range of 50 to 200 A is passed between the cathode electrode and the anode electrode of the Ti-Al-Ta alloy for forming the thin layer A to generate arc discharge, thereby A thin layer A having a predetermined layer thickness is formed on the surface of the substrate. After the thin layer A is formed, the arc discharge is stopped, and instead, between the cathode electrode and the anode electrode of the Ti-Al-Ta alloy for forming the thin layer B Similarly, a predetermined current in the range of 50 to 200 A is supplied to generate arc discharge to form a thin layer B having a predetermined thickness, and then the arc discharge is stopped (in this case, starting from the formation of the thin layer B). The thin layer A type Formation of thin layer A by arc discharge between cathode electrode and anode electrode of Ti-Al-Ta alloy for use, and thin layer by arc discharge between cathode electrode and anode electrode of Ti-Al-Ta alloy for formation of thin layer B The formation of B is alternately repeated so that the target composition shown in Table 2 along the layer thickness direction and the thin layer A and the thin layer B having a single target layer thickness are alternately laminated on the surface of the cemented carbide cutting base. Similarly, the coated super hard gear cutting tools 1 to 10 of the present invention were manufactured by vapor-depositing the upper layers to be formed with the overall target layer thicknesses shown in Table 2, respectively.

  Further, for the purpose of comparison, the above-described superhard gear cutting bases A to J are ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. As the (evaporation source), a Ti—Al—Ta alloy having a component composition corresponding to the target composition shown in Table 3 is mounted, and the apparatus is first evacuated and kept at a vacuum of 0.1 Pa or less. Then, after heating the inside of the apparatus to 500 ° C. with a heater, a DC bias voltage of −1000 V was applied to the cemented carbide cutting base, and 100 A was applied between the Ti—Al—Ta alloy of the cathode electrode and the anode electrode. An electric current is applied to generate an arc discharge, so that the surface of the cemented carbide cutting base is bombarded with the Ti—Al—Ta alloy, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 3 Pa. At the same time, the bias voltage applied to the cemented carbide cutting base is lowered to −100 V to generate an arc discharge between the cathode electrode and the anode electrode of the Ti—Al—Ta alloy. A comparative coated carbide gear cutting is performed by vapor-depositing a hard coating layer composed of a (Ti, Al, Ta) N layer having a single phase structure with the target composition and target layer thickness shown in Table 3 on the surface of the substrate. Tools 1-10 were produced respectively.

Next, for each of the present invention coated cemented carbide cutting tool 1-10 and comparative coated cemented carbide cutting tool 1-10,
(A) The material is JIS AC9B (composition, mass%, Al-19% Si-1% Cu-1% Mg-1% Ni),

Module: 1.5, Pressure angle: 14.5 degrees, Number of teeth: 27, Twist angle: 25 degrees Right-hand twist, Teeth width: Processing of gears with dimensions and shapes of 20 mm,

Cutting speed (rotational speed): 500 m / min,
Feed: 1.5mm / rev,
Processing form: climb, no shift, dry (air blow),
(The cutting speed in the case of the above-mentioned JIS / AC9B Al alloy gear machining is usually 350 m / min)

(B) The material is JIS / SUS303,

Module: 1.5, Pressure angle: 14.5 degrees, Number of teeth: 29, Twist angle: 30 degrees Right twist, Teeth width: Processing of gears with dimensions and shapes of 22.5 mm,

Cutting speed (rotational speed): 450 m / min,
Feed: 1.2mm / rev,
Processing form: climb, no shift, dry (air blow),
(The cutting speed in the case of processing the gear of the above-mentioned material JIS / SUS303 is usually 350 m / min)
In the high-speed gear cutting of (a) and (b) above, the number of gears processed until the flank wear width reached 0.1 mm was measured.

The measurement results are shown in Tables 2 and 3, respectively.

The thin layer A and the thin layer B constituting the hard coating layer made of (Ti, Al, Ta) N of the coated carbide cutting tool 1 to 10 of the present invention obtained as a result of this, and the composition of the lower layer In addition, the composition of the hard coating layer made of (Ti, Al, Ta) N of the comparative coated carbide gear cutting tools 1 to 10 was measured by an energy dispersive X-ray analysis method using a transmission electron microscope. Each showed substantially the same composition as the target composition.
Further, when the average layer thickness of the constituent layers of the hard coating layer was subjected to cross-sectional measurement using a transmission electron microscope, all showed the same average value (average value of five locations) as the target layer thickness.

From the results shown in Tables 2 and 3, the coated carbide cutting tool of the present invention has a single-phase structure lower layer made of (Ti, Al, Ta) N, each having a hard coating layer having a different composition, Consists of an upper layer having an alternating laminated structure of thin layers A and B each having a thickness of 5 to 20 nm, the lower layer has excellent high-temperature hardness, and the upper layer has excellent work material reactivity suppression Since the hard coating layer has these excellent characteristics, it is accompanied by high heat generation of highly reactive work materials such as Ti alloy, high Si content Al alloy, and stainless steel in particular. Even when used for high-speed gear cutting and when gear steel gears are cut under high-speed gear cutting conditions with high heat generation, the hard coating layer and the highly reactive work material The gear cutting is performed with the reaction wear being significantly suppressed Therefore, the comparative coated carbide gear cutting tool in which the hard coating layer is composed of a (Ti, Al, Ta) N layer having a single-phase structure, while exhibiting excellent wear resistance, is provided with the above-described highly reactive cutting. In high-speed gear cutting of materials, it is clear that the reactive wear between the hard coating layer and the highly reactive work material is particularly remarkable, and as a result, the service life is reached in a relatively short time.
As described above, the surface-coated cemented carbide cutting tool of the present invention (the coated carbide cutting tool of the present invention) is used for cutting under normal conditions such as various carbon steels, low alloy steels, and ordinary cast iron. In addition to machining, especially when the above high-reactive work materials are subjected to high-speed gear cutting with high heat generation, the hard coating layer exhibits excellent wear resistance and is excellent over a long period of time. Therefore, the present invention can satisfactorily cope with the high performance of the gear cutting apparatus, the labor saving and energy saving of the gear cutting, and the cost reduction.

The arc ion plating apparatus used for forming the hard coating layer which comprises the coated carbide gear cutting tool of this invention is shown, (a) is a schematic plan view, (b) is a schematic front view. It is a schematic explanatory drawing of a normal arc ion plating apparatus. It is a schematic perspective view of a cemented carbide cutting tool (solid hob).

Claims (1)

On the surface of the tungsten carbide base cemented carbide cutting tool base,
(A) Both are composed of an upper layer and a lower layer made of a composite nitride of Ti, Al, and Ta, the upper layer has an average layer thickness of 0.5 to 1.5 μm, and the lower layer has an average layer thickness of 2 to 6 μm. Have
(B) Each of the upper layers has an alternately laminated structure of thin layers A and B each having an average layer thickness of 5 to 20 nm (nanometer),
The thin layer A is
_{Formula: [Ti 1- (A + B} ) Al A Ta B] N ( provided that an atomic ratio, A is 0.01 to 0.10, B represents a 0.50 to 0.70) and Ti which satisfies A composite nitride layer of Al and Ta,
The thin layer B is
Ti satisfying the composition formula: [Ti _{1− (C + D)} Al _C Ta _D ] N (wherein C is 0.30 to 0.45 and D is 0.20 to 0.35 in atomic ratio) A composite nitride layer of Al and Ta,
(C) the lower layer has a single phase structure;
Ti satisfying the composition formula: [Ti _{1− (E + F)} Al _E Ta _F ] N (wherein E is 0.50 to 0.65 and F is 0.01 to 0.09 in atomic ratio) A composite nitride layer of Al and Ta,
A surface-coated cemented carbide cutting tool that exhibits excellent wear resistance in high-speed gear cutting of a highly reactive work material, characterized in that the hard coating layer is formed by vapor deposition.

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