JP2007136580A - Surface-coated cutting tool having hard coated layer exhibiting wear resistance and chipping resistance on high-speed heavy cutting condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool, having a hard coated layer exhibiting wear resistance and chipping resistance with high-speed heavy cutting conditions. <P>SOLUTION: The hard coated layer of the surface coated cutting tool includes (A) a lower layer and (B) an upper layer, wherein the lower layer is a Ti compound layer, which is formed by one layer or two kinds of layers from among TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer, and has a total average layer thickness, ranging from 0.5 to 15 μm, and the upper layer is a composite oxide layer of Al, Cr and Y, having an average layer thickness ranging from 3 to 15 μm, the composite oxide layer characterized in that:(a) it has a component concentration distribution structure, in which Al maximum content point and Cr maximum content point exist repeatedly alternately, at predetermined spaces and The Al content and Cr content are continuously varied between both points; (b) it satisfies a specific composition formula at the Al maximum content point and the Cr maximum content point; and further, (c) the space between the adjacent Al maximum content point and Cr maximum content point ranges from 0.1 to 0.5 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  This invention has excellent high-temperature strength and heat resistance in addition to excellent high-temperature hardness and heat resistance. Therefore, cutting of various steels and cast irons is especially added to high-speed conditions with high heat generation. Even under heavy cutting conditions such as high cutting and high feed that are subject to high mechanical impact, the hard coating layer has excellent wear resistance over a long period without chipping (small chipping). The present invention relates to a surface-coated cutting tool to be exhibited (hereinafter referred to as a coated tool).

Generally, as a coated tool, a surface of a substrate (hereinafter collectively referred to as a tool substrate) made of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet. In addition,
(A) As a lower layer, a Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition, Ti consisting of one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having an overall average layer thickness of 0.5 to 15 μm Compound layer,
(B) As an upper layer, a composition formula having an average layer thickness of 3 to 15 μm and showing a mutual content ratio of Al and Cr: (Al _1-M Cr _M ) (wherein M is 0. A composite oxide of Al and Cr that satisfies the requirements of 35 to 0.65 and has a solid solution structure of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) and chromium oxide (hereinafter referred to as Cr ₂ O ₃ ) [Hereinafter referred to as (Al—Cr) ₂ O ₃ ] layer,
There is known a coated tool formed by chemical vapor deposition of a hard coating layer composed of the lower layer and the upper layer.
Further, since the a top layer constituting the hard coating layer of the conventional coated tools (Al-Cr) ₂ O ₃ layers comprises a high-temperature hardness and heat resistance by Al, high-temperature strength by Cr, such It is also known to exhibit excellent cutting performance when the coated tool is used for continuous cutting and intermittent cutting of various types of steel and cast iron.

Further, in the above conventional coated tool, for example, as shown in a schematic longitudinal sectional view in FIG. 1, a reaction gas blowing pipe made of stainless steel is erected at the center, and the reaction gas blowing pipe has a structure shown in FIG. ) Is a schematic perspective view, and a graphite tool base support pallet exemplified in (b) is a schematic plan view. The structure is skewered and fitted, and these are heated by a heater through a stainless steel cover. A chemical vapor deposition apparatus having a tool base is loaded into the chemical vapor deposition apparatus in a state where the tool base is placed as illustrated in a plurality of reaction gas passage hole positions formed on the bottom surface of the tool base support pallet, and a heater Then, after heating the inside of the apparatus to a predetermined temperature within a range of 850 to 1050 ° C., for example, a Ti compound layer is first formed as a lower layer of the hard coating layer under the formation conditions shown in Table 3, for example. With reactive gas Te, by volume% (hereinafter,% of the reaction gas are capacitors%),
AlCl ₃ : 0.77 to 1.43%,
CrCl _2: 0.77~1.43%,
CO _2: 5~6%,
HCl: 2-3%,
H ₂ : Remaining
The reaction gas is introduced into the device that has been evacuated in advance through the reaction gas blowing pipe, and the reaction gas pressure in the device is set to a predetermined pressure within the range of 6 to 30 kPa. It is also known that it is manufactured by forming the upper layer composed of the (Al—Cr) ₂ O ₃ layer by holding it for a predetermined time.

In general, the Ti compound layer and the (Al—Cr) ₂ O ₃ layer constituting the lower layer of the hard coating layer of the conventional coated tool described above have a granular crystal structure, and further the TiCN constituting the Ti compound layer For the purpose of improving the strength of the layer itself, the layer is formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas in an ordinary chemical vapor deposition apparatus. It is also known to have a vertically elongated crystal structure.
JP 54-153758 A Japanese Patent Laid-Open No. 6-8010

  In recent years, there has been a remarkable increase in the performance of cutting equipment, while there has been a strong demand for labor saving and energy saving and further cost reduction for cutting work. Although there is a tendency to be forced to perform cutting under heavy cutting conditions such as high feed, the above-mentioned conventional coated tool performs heavy cutting such as high cutting with high mechanical impact and high feed at high speed. In particular, the (Al—Cr) 2 O 3 layer having a certain composition along the layer thickness direction constituting the upper layer of the hard coating layer has insufficient high-temperature hardness and heat resistance, and insufficient high-temperature strength. For this reason, not only the progress of wear is accelerated, but chipping (microcracking) is likely to occur, and as a result, the service life is reached in a relatively short time.

In view of the above, the present inventors have developed the above-mentioned conventional coated tool in order to develop a coated tool that exhibits excellent wear resistance and chipping resistance, particularly in a high-speed heavy cutting process. As a result of conducting research with a focus on the hard coating layer,
(A) The (Al—Cr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the conventional coated tool formed using the above chemical vapor deposition apparatus has a substantially uniform composition over the entire layer thickness. And has a solid solution structure, and therefore has a uniform high temperature hardness and heat resistance, and a high temperature strength. For example, as shown in the schematic chart of FIG. 3, the (Al—Cr) ₂ O _In a state where 1 to 10 atomic% of Y is contained in the proportion of the total amount of Al and Cr in the _three layers, the Al highest content point and the Cr highest content point are arranged at a predetermined interval along the layer thickness direction. For the purpose of alternately and repeatedly forming the reaction gas composition and the flow rate central control unit, the reaction gas composition corresponding to the Al highest content point and the Cr highest content point, and the continuous change of Al and Cr between the two points Reaction gas corresponding to Composition, further wherein the distance between two points, and inputs based on historical data, according to a control signal from the reaction gas composition and flow rates central control unit, AlCl ₃ gas from the raw material gas cylinder, CrCl ₂ gas, YCl _When the flow rate of ₃ gas, H ₂ gas, CO ₂ gas, and HCl gas is controlled by the respective raw material gas flow rate automatic control devices and introduced into the reaction gas blowing pipe of the chemical vapor deposition device, along the layer thickness direction, Al highest content point and Cr highest content point alternately and repeatedly exist at predetermined intervals, and Al and Cr from the highest Al content point to the highest Cr content point, from the highest Cr content point to the lowest Al content point The component concentration distribution structure in which the content changes continuously, and the mixed oxide phase of Al, Cr, and Y are separated in the solid solution substrate of Al ₂ O ₃ and Cr ₂ O _3. An upper layer composed of a composite oxide of Al, Cr, and Y (hereinafter referred to as (Al, Cr, Y) composite oxide) having a distributed structure is formed.

(B) In the (Al, Cr, Y) composite oxide layer having the repeated continuous change component concentration distribution structure of (a) above,
Formula shows the mutual proportion of Al, Cr, and Y in the Al highest content _{point: [Al 1- (A + B} ) Cr A Y B] ( where in atomic ratio, A is 0.02 to 0.15, B Represents 0.01 to 0.10),
Composition formula indicating the mutual content ratio of Cr, Al, and Y at the highest Cr content point: [Cr _{1- (C + D)} Al _C Y _D ] (where C is 0.02 to 0.15, D Represents 0.01 to 0.10),
And the interval in the thickness direction of the adjacent Al highest content point and Cr highest content point adjacent to each other is 0.1 to 0.5 μm,
In the Al highest content point portion, the Al content is relatively higher than that of the conventional (Al—Cr) ₂ O ₃ layer, and that of Cr is extremely low. In addition, it has excellent high-temperature hardness and heat resistance compared to heat resistance, but on the other hand, the high-temperature strength is low, and in the above-mentioned Cr highest content point portion, Al is higher than the Al highest content point portion. Since the content is low and the content of Cr is relatively high, it has higher high-temperature strength, but it has low high-temperature hardness and heat resistance. Since the distance between the layers is extremely small, the layer has excellent high-temperature strength and heat resistance as the characteristics of the entire layer, and has a further excellent high-temperature strength. By forming a structure in which a composite oxide of Al, Cr, and Y is dispersed and distributed, the high-temperature strength of the layer itself is further improved. Therefore, the upper layer of the hard coating layer is applied (Al, Cr, Y ) Coated oxide layer coated tools, especially when cutting various steels and cast irons at high speeds and under heavy cutting conditions such as high cutting and high feed with high mechanical impact, The hard coating layer has excellent wear resistance and chipping resistance.
The research results shown in (a) and (b) above were obtained.

This invention was made based on the above research results, and on the surface of the carbide substrate,
(A) As a lower layer, each is formed by one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer formed by chemical vapor deposition, and 0.5 to 15 μm A Ti compound layer having a total average layer thickness;
(B) As an upper layer, it has an average layer thickness of 3 to 15 μm, and
(A) formed by chemical vapor deposition, the highest Al content point and the highest Cr content point are alternately present at predetermined intervals along the layer thickness direction, and the highest Cr content point from the highest Al content point, A component concentration distribution structure in which the Al and Cr contents continuously change from the highest Cr content point to the highest Al content point,
(B) Composition formula showing the mutual content ratio of Al, Cr, and Y at the Al highest content point: [Al _{1- (A + B)} Cr _A Y _B ] (where A is 0.02 to 0.00. 15, B represents 0.01 to 0.10),
Composition formula indicating the mutual content ratio of Cr, Al, and Y at the highest Cr content point: [Cr _{1- (C + D)} Al _C Y _D ] (where C is 0.02 to 0.15, D Represents 0.01 to 0.10),
Satisfied,
(C) Furthermore, the interval between the adjacent Al highest content point and the Cr highest content point adjacent to each other is 0.1 to 0.5 μm.
An upper layer made of a (Al, Cr, Y) composite oxide layer that satisfies the above (a) to (c),
Characterized by coated carbide tools that exhibit excellent wear resistance and chipping resistance under high-speed heavy cutting conditions, formed by chemical vapor deposition of the hard coating layer composed of the lower and upper layers described above. I have it.

Next, in the coated carbide tool of the present invention, the reason why the structure of the hard coating layer constituting the tool is limited as described above will be described.
(A) Ti compound layer (lower layer)
The Ti compound layer basically exists as a lower layer of the (Al, Cr, Y) composite oxide layer and contributes to improving the high temperature strength of the hard coating layer by its excellent high temperature strength. And the (Al, Cr, Y) composite oxide layer firmly adheres to each other, and thus has an effect of improving the adhesion of the hard coating layer to the tool substrate, but when the average layer thickness is less than 0.5 μm, When the average layer thickness exceeds 15 μm, it is easy to cause thermoplastic deformation that causes uneven wear due to heat generated during cutting. It was determined to be 0.5 to 15 μm.

(B) (Al, Cr, Y) composite oxide layer (upper layer)
(A) Composition of the highest Al content point As described above, the Al component in the (Al, Cr, Y) composite oxide layer is high temperature hardness and heat resistance (high temperature characteristics), the Cr component improves the high temperature strength, and the Y component Has the effect of further improving the high-temperature strength. Therefore, at the highest Al content point, the Al component content should be increased to further improve the high-temperature hardness and heat resistance, making it suitable for high-speed cutting with high heat generation. However, in the composition formula showing the mutual content ratio of Al, Cr and Y components: [Al _{1- (A + B)} Cr _A Y _B ], the A value exceeds 0.15 in atomic ratio (the same shall apply hereinafter) If the B value exceeds 0.10, the content ratio of Al is relatively low, so that the high-temperature hardness and heat resistance of the layer itself are inevitably deteriorated, which causes wear promotion. The value is less than 0.02. If the B value is less than 0.01, even if the highest Cr content point having excellent high temperature strength is present adjacently, a decrease in the high temperature strength of the layer itself is inevitable, resulting in chipping and the like. defined _{[Al 1- (a + B)} Cr a Y B] 0.02~0.15 the a value in a the same B value 0.01 to _0.10: from becoming easily, the composition formula of Al highest content point It was.

(B) Composition of highest Cr content point As described above, the highest Al content point is excellent in high-temperature characteristics (high temperature hardness and heat resistance), but on the other hand, it is inferior in high-temperature strength. In order to compensate for the lack of high-temperature strength of the steel, by increasing the Cr content ratio and further including Y, which has a remarkable effect of improving the high-temperature strength, the highest Cr content points that have excellent high-temperature strength are alternately arranged in the thickness direction. However, the compositional formula showing the mutual content of Al, Cr and Y components: [Cr _{1- (C + D)} Al _C Y _D ], where the C value indicating the Al ratio is the total amount of Cr and Y If the ratio (atomic ratio) in the ratio is less than 0.02, the predetermined high-temperature characteristics cannot be ensured. As a result, even if there are adjacent Al highest content points having excellent high-temperature characteristics, the high temperature of the layer itself Inevitable deterioration of characteristics When this C value exceeds 0.15, on the other hand, the proportion of Cr becomes relatively low, and the high temperature strength of the layer itself is inevitably lowered, resulting in chipping and the like. Since it is easy to occur, the C value is determined to be 0.02 to 0.15. When the D value indicating the ratio of Y exceeds 0.10, deterioration of the high temperature characteristics of the layer itself can be avoided. On the other hand, this causes wear promotion. On the other hand, if the D value is less than 0.01, the desired high-temperature strength improvement effect cannot be obtained. Therefore, the composition formula of the highest Cr content point: [Cr _{1- (C + D)} Al _C In Y _D ], the C value was determined to be 0.02 to 0.15, and the D value was determined to be 0.01 to 0.10.

(C) Interval between the highest Al content point and the highest Cr content point If the distance is less than 0.1 μm, it is difficult to form each point clearly with the above composition. Hardness, heat resistance, and high temperature strength cannot be ensured. Also, when the interval exceeds 0.5 μm, each point has a defect, that is, if Al is the highest content point, insufficient high temperature strength, Cr highest content point Then, high temperature hardness and insufficient heat resistance appear locally in the layer, and this makes it easy to generate chipping and promotes the progress of wear. .5 μm.

(D) Average layer thickness If the average layer thickness is less than 3 μm, the desired wear resistance cannot be ensured over a long period of time. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. Therefore, the average layer thickness was determined to be 3 to 15 μm.

  In the coated tool of this invention, the uppermost layer of the hard coating layer has an Al highest content point having high temperature hardness and heat resistance excellent in the layer thickness direction and a Cr highest content point having excellent high temperature strength at predetermined intervals alternately. It has a component concentration distribution structure that repeatedly exists and the Al and Cr contents continuously change between the two points, whereby the hard coating layer has a superior interlaminar adhesion provided by the Ti compound layer as the lower layer High temperature hardness and heat resistance combined with high temperature and high temperature strength, as well as excellent high temperature strength, cutting various steels and cast irons at high speed and high mechanical impact. Even when performed under heavy cutting conditions such as high cutting and high feed, the hard coating layer exhibits excellent wear resistance and chipping resistance, and exhibits excellent cutting performance over a long period of time.

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

As raw material powders, WC powder, TiC powder, TiN powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintering is performed under holding conditions, and after sintering, tool bases A1 to A10 made of WC-base cemented carbide having ISO standard and CNMG120408 chip shape are subjected to honing of R: 0.07 on the cutting edge portion. Formed.

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.07 and ISO standard Tool bases B1 to B6 made of TiCN base cermet having a chip shape of CNMG120408 were formed.

Next, after each of the tool bases A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, the tool base support shown in FIG. 2 is placed in the chemical vapor deposition apparatus shown in FIG. First, in the state of being placed in the positioning hole of the pallet, first, the conditions for forming a TiCN layer having a vertically grown crystal structure as described in Table 3 (l-TiCN in Table 3 is described in JP-A-6-8010). In the normal conditions shown in Table 7), the combinations shown in Table 7 and the Ti compound layer having the target layer thickness are formed on the hard coating layer. After vapor deposition as a lower layer, the atmospheric temperature in the apparatus was also heated to 1020 ° C. with a heater, and the past was stored in the reaction gas composition and flow rate central control apparatus of the reaction gas composition automatic control system shown in FIG. According to the actual data, the target composition formula showing the mutual content ratio of Al, Cr and Y at the highest Al content point shown in Tables 4 and 5, and the mutual content ratio of Cr, Al and Y at the highest Cr content point are shown. Relationship between target composition and reaction gas composition, reaction gas composition corresponding to continuous change in Al and Cr content between the Al highest content point and the Cr highest content point, and also the target interval between the two points shown in Table 7 And a target layer thickness as an upper layer of the hard coating layer is inputted, and H ₂ which is a raw material gas is passed through a raw material gas flow rate automatic control device with a built-in control valve which operates in accordance with the reaction gas composition and a signal from the flow rate central control device. gas, CO ₂ gas, and HCl gas (Note, AlCl ₃ gas, CrCl ₂ also as the raw material gas, and YCl ₃ gas, respectively AlCl ₃ gas Raw devices, CrCl ₂ gas generator, and metal Al in YCl ₃ gas generator, a metal Cr, and a is formed by reacting respectively) metal Y and HCl gas, while controlling the respective gas flow rates, FIG. 1 is introduced into the apparatus through the reaction gas blowing pipe of the chemical vapor deposition apparatus 1 (the reaction atmosphere pressure in the apparatus is always maintained at 10 kPa), and thus the surface of the tool base is arranged along the layer thickness direction in Tables 4 and 5 The highest Al content point and the highest Cr content point of the target composition formula shown in FIG. 7 are alternately repeated at the target intervals shown in Table 7, and from the highest Al content point, the highest Cr content point, the highest Cr content (Al, Cr, Y) having a component concentration distribution structure in which the Al and Cr contents continuously change from the content point to the Al highest content point, respectively, and also having the target layer thickness shown in Table 7 By depositing the composite oxide layer as an upper layer of the hard coating layer, the present surface-coated throwaway tips (hereinafter referred to as the present invention-coated tips) 1 to 16 which are the present coated tools were produced.

  For comparison purposes, these tool bases A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone and dried, and then charged into the normal chemical vapor deposition apparatus shown in FIGS. When forming the upper layer of the hard coating layer, except that the reaction gas introduced from the reaction gas blowing tube is a reaction gas having a composition corresponding to the target composition formula showing the mutual content ratio of Al and Cr shown in Table 6, respectively. Under the same conditions, the surface of each of the tool bases A1 to A10 and B1 to B6 has the same target layer thickness as shown in Table 8 and substantially no composition change along the layer thickness direction ( By depositing an Al—Cr) 2 O 3 layer as an upper layer of the hard coating layer, conventional surface-coated throwaway tips (hereinafter referred to as conventional coated tips) 1 to 16 as conventional coated tools are manufactured, respectively. .

Next, for the above-mentioned coated chips 1-16 of the present invention and the conventional coated chips 1-16, this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SCM415 round bar,
Cutting speed: 500 m / min. ,
Cutting depth: 5 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed high-cut cutting test of alloy steel under the following conditions (referred to as cutting condition A) (normal cutting speed and cutting are 250 m / min. And 2 mm),
Work material: JIS / S20C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 450 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.55 mm / rev. ,
Cutting time: 5 minutes,
Of carbon steel under the following conditions (referred to as cutting condition B) (a normal cutting speed and feed are 200 m / min. And 0.3 mm / rev.),
Work material: JIS / FC150 round bar,
Cutting speed: 600 m / min. ,
Cutting depth: 5.0 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes,
The dry continuous high-speed, high-cut cutting test (normal cutting speed and cutting is 250 m / min. And 2.0 mm) of cast iron under the above conditions (referred to as cutting condition C). The surface wear width was measured. The measurement results are shown in Table 9.

For the upper layers of the hard coating layer constituting the coated chips 1 to 16 of the present invention and the conventional coated chips 1 to 16 obtained as a result, the contents of Al, Cr, and Y along the thickness direction are Auger spectroscopic analyzers The content of Al, Cr, and Y at each measurement point was calculated from the measurement results. In the upper layers of the coated chips 1 to 16, the highest Al content point and the highest Cr content point Are alternately and repeatedly present at substantially the same interval as the composition and the target interval that substantially satisfy the target composition formula, and from the highest Al content point to the highest Cr content point, from the highest Cr content point to the highest Al content point On the other hand, it is confirmed that the upper and lower hard coating layers of the conventional coated chips 1 to 16 substantially satisfy the target composition formula. It shows a composition which is the composition varies along the thickness direction was observed.
Further, when the composition of the Ti compound layer constituting the lower layer of the hard coating layer was measured in the same manner, both showed substantially the same composition as the target composition, and further, the upper layer and the lower layer constituting the hard coating layer The average layer thickness was substantially the same as the target layer thickness.

From the results shown in Tables 7 to 9, the uppermost layer of the hard coating layer has a highest Cr content having a relatively high high temperature hardness and heat resistance, and a relatively high high temperature strength in the layer thickness direction. Al and Cr content continuously change from the highest Al content point to the highest Cr content point and from the highest Cr content point to the highest Al content point. The coated chips 1 to 16 of the present invention having a component concentration distribution structure are capable of cutting various steels and cast irons at high speeds and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. When performed, the hard coating layer exhibits excellent chipping resistance and excellent wear resistance over a long period of time, whereas the upper layer of the hard coating layer extends along the layer thickness direction. Substantially no composition change (A In conventional coating chips 1-16 consisting -Cr) ₂ O ₃ layer, in particular an upper layer of the hard coating layer, high-temperature hardness and heat resistance comprising the upper layer of the present invention cover the chip 1 to 16, further Since it is relatively inferior to the high-temperature strength, chipping is likely to occur and wear progresses rapidly, so that it is clear that the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention is capable of cutting various steels and cast irons as well as cutting under normal conditions at high speeds and with high cutting and high mechanical impact. Even when performed under heavy cutting conditions such as feeding, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It is possible to cope with the conversion sufficiently satisfactorily.

It is a schematic longitudinal cross-sectional view which shows the chemical vapor deposition apparatus used in forming the hard coating layer which comprises a coating tool. The tool base support pallet which is a structural member of a chemical vapor deposition apparatus is shown, (a) is a schematic perspective view, (b) is a schematic plan view. It is the reaction gas composition automatic control system used for formation of the upper layer of the hard coating layer which comprises the coating tool of this invention.

Claims (1)

On the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate,
(A) As a lower layer, it is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer formed by chemical vapor deposition. And a Ti compound layer having a total average layer thickness of 0.5 to 15 μm,
(B) As an upper layer, it has an average layer thickness of 3 to 15 μm, and
(A) formed by chemical vapor deposition, the highest Al content point and the highest Cr content point are alternately present at predetermined intervals along the layer thickness direction, and the highest Cr content point from the highest Al content point, A component concentration distribution structure in which the Al and Cr contents continuously change from the highest Cr content point to the highest Al content point,
(B) Composition formula showing the mutual content ratio of Al, Cr, and Y at the Al highest content point: [Al _{1- (A + B)} Cr _A Y _B ] (where A is 0.02 to 0.00. 15, B represents 0.01 to 0.10),
Composition formula indicating the mutual content ratio of Cr, Al, and Y at the highest Cr content point: [Cr _{1- (C + D)} Al _C Y _D ] (where C is 0.02 to 0.15, D Represents 0.01 to 0.10),
Satisfied,
(C) Furthermore, the interval between the adjacent Al highest content point and the Cr highest content point adjacent to each other is 0.1 to 0.5 μm.
An upper layer composed of a composite oxide layer of Al, Cr and Y satisfying the above (a) to (c);
A surface-coated cutting tool that exhibits excellent wear resistance and chipping resistance under high-speed heavy cutting conditions, formed by chemical vapor deposition of a hard coating layer composed of the lower layer and the upper layer.

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