JP2004306246A - Tool for cutting surface covering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool with a long service life having excellent chipping resistance and wear resistance by which the adhesiveness of a hard covering layer can be enhanced without generating peeling between a TiCN layer and an Al<SB>2</SB>O<SB>3</SB>layer in severe cutting conditions such that strong impact is imposed particularly on the cutting edge of the tool of intermitting cutting or the like. <P>SOLUTION: The TiCN layer 4 is composed of a streak-like TiCN crystal which is made to grow in the vertical direction to the base material 2, and also an average crystal width<SB>w1</SB>in the side of the Al<SB>2</SB>O<SB>3</SB>layer 6 of the TiCN layer 4 is made larger than an average crystal width<SB>w2</SB>in the side of the base material 2, in the tool 1 for cutting a surface covering forming the hard covering layer 3 providing the Al<SB>2</SB>O<SB>3</SB>layer 6 on the surface of the TiCN layer 4 by being deposited, by providing at least one layer of the TiCN layer 4 on the surface of the base material 2 consisting of cemented carbide or cermet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface-coated cutting tool in which a hard coating layer having excellent chipping resistance and wear resistance is formed on the surface thereof, and in particular, even in cutting where a large impact such as intermittent cutting of metal is applied to the cutting blade. The present invention relates to a surface-coated cutting tool having excellent fracture resistance and cutting characteristics.

Conventionally, cutting tools widely used for metal cutting are hard coatings such as a TiC layer, a TiN layer, an Al ₂ O ₃ layer, and a TiCN layer on the surface of a base material such as cemented carbide, cermet, or ceramic. A surface-coated cutting tool in which a single layer or a plurality of layers is formed is often used.

  On the other hand, in cutting where a large impact such as heavy interrupted cutting of metal is applied to the cutting edge in accordance with the recent improvement in cutting efficiency, the hard coating layer cannot withstand the large impact with conventional tools, and chipping is performed on the rake face. And the hard coating layer is easily peeled off, which causes a problem that the tool life cannot be extended due to sudden tool damage such as chipping of the cutting edge or abnormal wear.

As the hard coating layer, Patent Document 1 describes that delamination is suppressed by dividing a TiCN layer having a vertically grown crystal by a granular TiN layer or the like, and can improve the fracture resistance of a tool. Is described.
Japanese Patent No. 3230372

However, even with the structure of the TiCN layer described in the above-mentioned Patent Document 1, the problem that the hard coating layer easily peels off in the vicinity of the interface between the Al ₂ O ₃ layer and the TiCN layer cannot be solved. In cutting that requires a large impact such as heavy interrupted cutting, chipping and peeling of the hard coating layer still occurred at the interface between the TiCN layer and the Al ₂ O ₃ layer. If the thickness of the hard coating layer is reduced for the purpose of preventing chipping of the hard coating layer or peeling of the hard coating layer, the hard coating layer disappears earlier and the wear progresses faster, which also increases the tool life. It was not possible.

Furthermore, if the TiCN layer is configured in consideration of the adhesiveness with the Al ₂ O ₃ layer only, the adhesiveness with the base material is impaired and the TiCN layer itself is peeled off, and the tool life is limited. .

Accordingly, the present invention has been made to solve the above-described problems, and the object thereof is to provide a hard coating layer even under severe cutting conditions in which a strong impact is applied to a tool cutting edge such as intermittent cutting of metal. The adhesion of the hard coating layer can be improved without causing chipping or peeling of the hard coating layer near the interface between the Al ₂ O ₃ layer and the TiCN layer, and has excellent fracture resistance and wear resistance. It is to provide a long-life cutting tool.

The present inventor has studied a method for increasing the fracture resistance without impairing the wear resistance of a cutting tool having a hard coating layer in which a TiCN layer and an Al ₂ O ₃ layer are sequentially provided on the surface of the base material. As a result, the TiCN layer of the surface-coated cutting tool is composed of streak TiCN crystals grown in a direction perpendicular to the base material, and the average crystal width on the Al ₂ O ₃ layer side of the TiCN layer is determined on the base material side. By making it larger than the average crystal width, the interlayer adhesion between the base material, the TiCN layer and the Al ₂ O ₃ layer can be improved. As a result, particularly in the case of gray cast iron (FC material) and ductile cast iron (FCD material). Near the interface of the base material, TiCN layer, and Al ₂ O ₃ layer even under severe cutting conditions where a strong impact is applied to the tool cutting edge, such as heavy interrupted cutting of metals such as cast iron in which high-hardness graphite particles are dispersed No Even the Al ₂ O ₃ layer from being able to maintain a strong adhesion of the hard coating layer even when the large thickness required for improving wear resistance, excellent wear resistance and without ping or delamination occurs It has been found that a cutting tool having a chipping property can be obtained.

That is, the surface-coated cutting tool of the present invention is a surface-coated cutting tool comprising a hard coating layer in which at least a TiCN layer and an Al ₂ O ₃ layer are sequentially formed on the surface of a base material made of a hard alloy. The layer is made of streaked TiCN crystals grown in a direction perpendicular to the base material, and the average crystal width of the streaked TiCN crystals on the Al ₂ O ₃ layer side is larger than the average crystal width on the base material side. This is a surface-coated cutting tool.

Moreover, it is desirable that the average crystal width of the streaky TiCN crystal layer on the Al ₂ O ₃ layer side is 0.5 to 1.0 μm.

  Furthermore, it is desirable that the average crystal width of the streaked TiCN crystal layer on the base material side is 0.1 to 0.7 μm.

Further, it is desirable that the TiCN layer is a multilayer of two or more layers in which the average crystal width of the streak TiCN crystal is increased on the Al ₂ O ₃ layer side.

  Furthermore, it is desirable that at least one layer selected from the group of TiN, TiCN, TiC, TiCNO, TiCO, and TiNO is interposed between the layers in the multilayer TiCN layer.

The Al ₂ O ₃ layer preferably has an α-type crystal structure.

According to the surface-coated cutting tool of the present invention, the TiCN layer is composed of a streaked TiCN layer growing perpendicularly to the surface of the base material, and the average crystal width of the streaked TiCN layer on the Al ₂ O ₃ layer side is determined as the base. By making it wider than the average crystal width on the material side, the base material, the TiCN layer and the Al ₂ O ₃ layer can be used even under severe cutting conditions such as a heavy interrupted cutting of a metal, especially when severe impact is applied to the tool cutting edge. Since a strong interlayer adhesion between the hard coating layer and the base material can be maintained without causing separation at the layer interface, a cutting tool having excellent wear resistance and fracture resistance can be obtained.

  An example of the surface-coated cutting tool of the present invention will be described with reference to FIG. 1 which is a scanning electron microscope (SEM) photograph of a fractured surface including a hard coating layer and FIG. 2 which is a schematic diagram thereof.

  According to FIG. 1, a surface-coated cutting tool (hereinafter simply referred to as a tool) 1 includes tungsten carbide (WC) and, optionally, carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals of the periodic table. Cemented carbide or titanium carbide (TiC) or carbonitriding in which a hard phase composed of at least one selected from the group of materials is bonded with a binder phase composed of an iron group metal of cobalt (Co) and / or nickel (Ni) A hard phase composed of at least one selected from the group consisting of carbides, nitrides, and carbonitrides of the group 4a, 5a, and 6a metals of the periodic table mainly composed of titanium (TiCN) is cobalt (Co) and / or nickel (Ni The hard coating layer 3 is deposited on the surface of a base material 2 made of a hard alloy such as cermet and bonded with a binder phase made of an iron group metal.

According to the present invention, the hard coating layer 3 formed on the tool 1 has a TiCN layer (hereinafter referred to as a streak-like TiCN layer) composed of streak-like TiCN crystals 8 that grow at least perpendicularly to the surface of the base material 2. 4) and Al ₂ O ₃ layer 6 are successively formed in order to form a multilayer structure, thereby exhibiting excellent wear resistance and fracture resistance and obtaining a long-life tool 1. Can do.

That is, if the Al ₂ O ₃ layer 6 is not formed, the wear resistance of the tool and the welding resistance to the work material are lowered, and the streak TiCN layer 4 is not formed immediately below the Al ₂ O ₃ layer 6. And the chipping resistance of the hard coating layer 3 is lowered.

Here, when the average TiW crystal 8 of the streaky TiCN layer 4 located immediately below the Al ₂ O ₃ layer is refined as a whole to reduce the average crystal width w, the wear resistance is improved and the streaked TiCN is formed. Interlayer adhesion between the layer 4 and the base material 2 is increased, and peeling of the streak TiCN layer 4 can be suppressed. However, the toughness of the streak TiCN layer 4 tends to decrease and the base material 2 and the streak TiCN layer 4 and the Al ₂ O ₃ layer 6 are deteriorated in interlayer adhesion, and the Al ₂ O ₃ layer 6 is likely to be peeled off from the streak TiCN layer 4, which may cause abnormal wear and cutting edge defects. There is.

On the other hand, when the streak TiCN crystal 8 of the streak TiCN layer 4 is coarsened to increase the average crystal width w, the interlayer adhesion between the Al ₂ O ₃ layer 6 and the streak TiCN layer 4 can be improved. Although peeling of the Al ₂ O ₃ layer 6 can be prevented, interlayer adhesion between the base material 2 and the streak TiCN layer 4 is deteriorated, and the streak TiCN layer 4 is easily peeled from the base material 2. After all, abnormal wear and chipping of the cutting edge occur.

Therefore, in the tool 1 of the present invention, as shown in FIG. 1 and FIG. 2, the Al ₂ O ₃ layer 6 side of the streak TiCN layer 4 (specifically, the Al ₂ O ₃ layer 6 of the streak TiCN layer 4 and The average crystal width w _{1 at} a position of 0.5 μm (h ₁ and line A) perpendicular to the base material 2 from the interface of the base material 2 side of the streaked TiCN layer 4 (specifically, streak-like) A streak TiCN layer at a position of 1 μm in the direction perpendicular to the interface from the interface with the base material 2 of the TiCN layer 4 (height h ₂ beyond the region where the crystal width is small due to nucleation and line B)) 4 is larger than the average crystal width w _{2 of} 4. By doing so, the interlayer adhesion of the base material 2, the streaky TiCN layer 4 and the Al ₂ O ₃ layer 6 can be enhanced together, especially in such a severe condition that a strong impact is applied to a cutting edge such as heavy interrupted cutting of cast iron. Even under various cutting conditions, chipping and film peeling near the layer interface of the base material 2, the streaky TiCN layer 4 and the Al ₂ O ₃ layer 6 can be suppressed, and the base material 2 and the hard coating layer 3 are firmly Since the interlayer adhesion can be maintained, it is possible to obtain a long-life tool 1 that retains excellent wear resistance and fracture resistance and suppresses film peeling.

Here, the average crystal width w ₁ at a height position (line B) of 1 μm from the interface between the streak TiCN layer 4 and the base material 2 toward the Al ₂ O ₃ layer 6 is 0.1 to 0.7 μm. This is desirable in terms of improving the adhesion to the base material 2, the wear resistance and fracture resistance of the tool 1, and extending the tool life.

Furthermore, the average crystal width w ₂ at a height position (line A) of 0.5 μm from the interface between the streaky TiCN layer 4 and the Al ₂ O ₃ layer 6 toward the base material is set to 0.5 to 1.0 μm. This is desirable in terms of improving the interlayer adhesion between the Al ₂ O ₃ layer and the streak TiCN layer 4 and preventing the wear resistance from being deteriorated due to film peeling.

The streak TiCN layer 4 of the present invention is composed of a fan-shaped crystal in which the average crystal width w continuously increases toward the upper portion (Al ₂ O ₃ layer 6) of the streak TiCN layer 4. However, as shown in FIGS. 1 and 2, the streak TiCN layer 4 is composed of two or more layers (streak TiCN layer 4a, streak TiCN layer 4b) having different average crystal widths w. The multilayer streak TiCN layer 4 can further improve the fracture resistance of the streak TiCN layer 4 as a whole by exhibiting a cushioning effect that the TiCN layer 4a having a large average crystal width w receives the collision stepwise. It is desirable from the viewpoint of further improving the interlayer adhesion between the Al ₂ O ₃ layer 6 and the base material 2 and controlling the average crystal width of the streak TiCN layer 4. In FIGS. 1 and 2, the streak TiCN layer 4 is formed in two layers having different average crystal widths w. However, the present invention is not limited to this, and a multilayer of three or more layers may be used. Good. Further, when the streak TiCN layer 4 has a multilayer structure, the film thickness in each layer is preferably 2 to 10 μm. Here, by setting the film thickness ratio of the uppermost streaky TiCN layer 4a and the lowermost streaky TiCN layer 4b to 1: 9 to 3: 7, the base material 2 is obtained without impairing fracture resistance. This is desirable in that the interlayer adhesion between the streaky TiCN layer 4 and the Al ₂ O ₃ layer can be improved. Furthermore, it is desirable that the total film thickness of the streak TiCN layer 4 when the streak TiCN layer 4 has a multilayer structure is 8 to 12 μm.

Further, the film thickness of the Al ₂ O ₃ layer 6 is _{3 to} 8 μm, and while maintaining the wear resistance, particularly the wear resistance and welding resistance to cast iron, the film peeling is prevented and the fracture resistance is increased. It is desirable in that it can.

  Here, at least one layer selected from the group of TiN, TiCN, TiC, TiCNO, TiCO, and TiNO is provided between the streaked TiCN layer 4a and the streaked TiCN layer 4b when the streaked TiCN layer 4 has a multilayer structure. The intermediate layer 7 prevents the base material component from diffusing, prevents the wear resistance of the hard coating layer 3 from being lowered, and can alleviate the impact caused by cutting. This is desirable because the chipping resistance in cutting can be improved. Moreover, it is desirable that the total film thickness of the intermediate layer 7 is 0.1 to 1 μm in terms of improving the fracture resistance.

  In addition, since TiN is formed as the surface layer 9 of the hard coating layer 3, the tool 1 exhibits a gold color, so that when the tool 1 is used, it is easy to determine whether it has been used by changing color, and the progress of wear. This is desirable because it can be easily confirmed.

Note that the Al ₂ O ₃ layer 6 used in the present invention preferably has an α-type crystal structure. Conventionally, Al ₂ O ₃ having an α-type crystal structure has excellent wear resistance. However, since the particle size at the time of nucleation is large, the contact area with the streak TiCN layer 4 is reduced, and the adhesive force is reduced. There was a problem that the film was weakened and the film was easily peeled off. However, since the contact area between the Al ₂ O ₃ layer and the streak TiCN layer 4 can be increased by adopting the configuration of the present invention, sufficient adhesion can be obtained even if the Al ₂ O ₃ layer 6 has an α-type crystal structure. Can be obtained. Therefore, since the excellent wear resistance of Al ₂ O ₃ having the α-type crystal structure can be obtained without reducing the adhesion of the Al ₂ O ₃ layer, the tool 1 having a longer tool life can be obtained. . When the Al ₂ O ₃ layer 6 has an α-type crystal structure, any of a TiCO layer, a TiNO layer, or a TiCNO layer of 0.2 μm or less between the streaky TiCN layer 4 and the Al ₂ O ₃ layer 6 is used. It is desirable that the α-type crystal structure can be stably grown.

(Production method)
In order to manufacture the above-mentioned surface-coated cutting tool, first, an inorganic powder such as a metal carbide, nitride, carbonitride, oxide, etc. that can form the above-mentioned hard alloy by firing, metal powder, carbon powder, etc. Are added and mixed as appropriate, and then molded into a predetermined tool shape by a known molding method such as press molding, cast molding, extrusion molding, or cold isostatic pressing, and then fired in a vacuum or non-oxidizing atmosphere. Thus, the base material 2 made of the hard alloy described above is produced.

Next, the hard coating layer 3 is formed on the surface of the base material 2 by, for example, chemical vapor deposition. The film-forming conditions of the streaky TiCN layer 4 are, for example, 0.1% to 10% by volume of TiCl ₄ gas, 0 to 60% by volume of N ₂ gas, 0 to 0% of CH ₄ gas as a reaction gas composition. 0.1% by volume, CH ₃ CN gas is 0.1-3% by volume, and the remaining gas mixture is H ₂ gas, and the mixture is introduced into the reaction chamber, and the chamber is heated to 800-1100 ° C. and 5-85 kPa. To form a film.

In the present invention, CH ₃ CN in the reaction gas used for film formation in CH _{3 CN} Al ₂ O 3 layer 6 side than the proportion of the reaction gas used for film formation in the base material 2 side By increasing the ratio, the average particle width w ₁ on the Al ₂ O ₃ layer 6 side can be made larger than the average particle width w ₂ on the base material 2 side in the streak TiCN layer 4. For example, a 2.2% by volume ratio of of _CH 3 CN _{the Al} 2 _{O 3} layer 6 side the proportion of _CH 3 CN at 1.1% by volume in the base material side. Further, the proportion of CH ₃ CN in the reaction gas may be increased stepwise or continuously as the film is formed.

Here, if the proportion of the CH ₃ CN gas in the reaction gas is less than 0.1% by volume among the above film formation conditions, the streak TiCN layer 4 cannot be grown to streak TiCN crystals, and the reaction is reversed. If the proportion of CH ₃ CN gas in the gas exceeds 3% by volume, the average crystal width w of the streak TiCN crystal 8 of the streak TiCN layer 4 cannot be controlled.

In addition, instead of the proportion of CH ₃ CN in the reaction gas, the streaks of the streaked TiCN layer 4 can be also obtained by increasing the film forming temperature during the formation of the streaked TiCN layer 4 on the Al ₂ O ₃ layer 6 side. It is possible to change the average crystal width of the TiCN crystal.

In addition, according to the present invention, the Al ₂ O ₃ layer 6 is continuously formed. As a method for forming the Al ₂ O ₃ layer 6, AlCl ₃ gas is 3 to 20% by volume, HCl gas is 0.5 to 3.5% by volume, CO ₂ gas is 0.01 to 5.0% by volume, It is desirable to use a mixed gas composed of 0 to 0.01% by volume of H ₂ S gas and the remaining H ₂ gas, and 900 to 1100 ° C. and 5 to 10 kPa.

When forming the intermediate layer 7 between the streak TiCN layer 4a and the streak TiCN layer 4b when the streak TiCN layer 4 has a multilayer structure, for example, a TiN layer is formed as the intermediate layer 7. Is prepared by sequentially adjusting a mixed gas composed of 0.1 to 10% by volume of TiCl ₄ gas, 0 to 60% by volume of N ₂ gas, and the remainder of H ₂ gas as a reaction gas composition, and introducing the mixture into the reaction chamber. The inside may be 800 to 1100 ° C. and 5 to 85 kPa.

When the surface layer 9 is formed on the tool 1, for example, in order to form a TiN layer as the surface layer 9, the reactive gas composition is 0.1 to 10% by volume of TiCl ₄ gas and 0 to 60% of N ₂ gas. %, The remaining mixed gas consisting of H ₂ gas is sequentially adjusted and introduced into the reaction chamber, and the inside of the chamber may be set to 800 to 1100 ° C. and 5 to 85 kPa.

Further, when the Al ₂ O ₃ layer 6 has an α-type crystal structure, after the formation of the streaky TiCN layer, 0.1 to 3% by volume of TiCl ₄ gas, 0.1 to 10% by volume of CH ₄ gas, A mixed gas composed of 0.01 to 5% by volume of CO ₂ gas, 0 to 60% by volume of N ₂ gas, and the remaining H ₂ gas is sequentially adjusted and introduced into the reaction chamber, and the inside of the chamber is 800 to 1100 ° C. 5 to 85 kPa.

(Example 1)
Tungsten carbide (WC) powder having an average particle size of 1.5 μm, metallic cobalt (Co) powder having an average particle size of 1.2 μm, and inorganic compound powders of Group 4a, 5a, and 6a metals in the periodic table having an average particle size of 2.0 μm Are added, mixed, and formed into a cutting tool shape (CNMA 12020412) by press forming, and then subjected to binder removal treatment, and further heated to 1000 ° C. or higher at a rate of 3 ° C./min to obtain a vacuum of 0.01 Pa. Inside, it hardened | cured at 1500 degreeC for 1 hour, and produced the cemented carbide.

Then, various hard coating layers were formed on the cemented carbide by the CVD method under the conditions shown in Table 1 to prepare surface-coated cutting tools of sample Nos. 1 to 9 having the film configurations shown in Table 2. . The average crystal width of the streak TiCN layer is measured by measuring the number of grain boundaries crossing the lines A and B at five arbitrary fractured surfaces including the hard coating layer of the tool as shown in FIG. It is the average value of five places of the value converted into the crystal width of the TiCN crystal. When forming the α-Al ₂ O ₃ layer, the TiCNO layer is formed to a thickness of 0.1 μm under the conditions shown in Table 1 before forming the Al ₂ O ₃ layer.

In all the samples, a TiN layer having a thickness of 1 μm was formed on the surface of the Al ₂ O ₃ layer as a surface layer under the conditions shown in Table 1, but the description in Table 2 was omitted.

  Then, using this cutting tool, the ductile cast iron was cut for 25 minutes under the following conditions, the cutting edge of the cutting tool was observed, and the flank wear amount and the tip wear amount were measured. Furthermore, an intermittent test and a film peeling test were performed on the grooved steel material, and the number of impacts when the chip was lost was compared in the intermittent test. Further, in the intermittent test, the state of the cutting edge when the number of impacts reached 1000 was confirmed with a microscope to confirm the peeling state of the hard coating layer. The results are shown in Table 3.

(Abrasion test)
Work material: Ductile cast iron (FCD450)
Tool shape: CNMA120204
Cutting speed: 350 m / min Feeding speed: 0.4 mm / rev
Cutting depth: 2mm
Other: Use of water-soluble cutting fluid (intermittent test)
Work material: Carbon steel (S45C)
Tool shape: CNMA120204
Cutting speed: 200 m / min Feeding speed: 0.3 to 0.5 mm / rev
Cutting depth: 2mm
Other: Uses water-soluble cutting fluid

  From Tables 2 and 3, sample No. 1 in which a TiCN layer made of granular crystals was formed. In No. 9, the chipping resistance was remarkably lowered and defects were generated at an early stage. In addition, the wear due to this defect progressed quickly.

Sample No. 1 consisting of a single TiCN layer was also used. In No. 8, delamination occurred between the TiCN layer and the Al ₂ O ₃ layer at the cutting edge, and the cutting performance deteriorated.

Further, a sample in which two or more layers are formed under the same conditions, and the average crystal width on the Al ₂ O ₃ layer side and the average crystal width on the base material side of the streaky TiCN crystal in the TiCN layer are the same. No. 6 and 7, delamination occurs at the interface between the streaked TiCN layer and the base material, or the streaked TiCN layer and the Al ₂ O ₃ layer in the hard coating layer of the cutting edge portion, and the fracture resistance decreases. Abnormal wear progressed from the place where peeling occurred, and the amount of wear increased.

On the other hand, in accordance with the present invention, the hard coating layer was prepared using sample No. 1 in which the average particle width on the Al ₂ O ₃ layer side of the streak TiCN layer was larger than the average particle width on the base material side. In Nos. 1 to 5, peeling of the hard coating layer did not occur, and both the chipping resistance and wear resistance were excellent.

(Example 2)
With respect to the TiCN (c) film formation conditions in Table 1 of Example 1, the ratio of CH ₃ CN in the mixed gas was continuously changed from 1.1% by volume to 2.2% by volume at the end of film formation. A cutting tool was produced in which a hard coating layer having the same film configuration as that of Sample No. 9 was formed under the same conditions as TiCN1 (c) except that the conditions were increased.

Further, the average crystal width on the Al ₂ O ₃ layer side of the streak TiCN crystal in the streak TiCN layer was 1.0 μm, and the average crystal width on the base material side was 0.3 μm.

  The manufactured cutting tool was evaluated in the same manner as in Example 1. As a result, in the wear resistance test, the flank wear amount was 0.22 mm and the tip wear amount was 0.21 mm. Next, in the chipping resistance test, the chip was chipped after 3200 impacts. Moreover, peeling of the hard coating layer of the cutting edge was not seen in the fracture resistance test.

It is a scanning electron micrograph of the fracture surface of the surface coating cutting tool by this invention. It is a fracture surface schematic diagram of the surface covering cutting tool of the present invention.

Explanation of symbols

1: Surface coated cutting tool 2: Base material 3: Hard coating layer 4: Streaked TiCN layer 4a: Streaked TiCN layer on the Al ₂ O ₃ layer side 4b: Streaked TiCN layer 6 on the base material side 6: Al ₂ O ₃ Layer 7: Intermediate layer 8: Streak particles A: Line B showing a position of 0.5 μm from the interface between the Al ₂ O ₃ layer and the streak TiCN layer toward the base material B: Between the base material and the streak TiCN layer lines _w 1 showing a 1μm position of toward _{the Al} 2 _{O 3} layer than the interface: the average crystal width of _{the Al} 2 _{O 3} layer side streaky TiCN layer _w 2: streaked TiCN layer average crystal width h of the base material side of the ₁ : Height position for measuring the crystal width on the Al ₂ O ₃ layer side of the streak TiCN layer h ₂ : Height position for measuring the average crystal width on the base material side of the streak TiCN layer

Claims (6)

In a surface-coated cutting tool having a hard coating layer in which at least a TiCN layer and an Al ₂ O ₃ layer are sequentially formed on the surface of a base material made of a hard alloy, the TiCN layer is perpendicular to the base material. A surface-coated cutting tool comprising a streak TiCN crystal grown in any direction and having an average crystal width on the Al ₂ O ₃ layer side of the streak TiCN crystal larger than the average crystal width on the base material side. The surface-coated cutting tool according to claim 1, wherein an average crystal width of the streaked TiCN crystal on the Al ₂ O ₃ layer side is 0.5 to 1.0 µm. The surface-coated cutting tool according to claim 1 or 2, wherein an average crystal width on the base material side of the streak-like TiCN crystal is 0.1 to 0.7 µm. The surface-coated cutting according to any one of claims 1 to 3, wherein the TiCN layer is a multilayer of two or more layers in which an average crystal width of the streaked TiCN crystal becomes larger on the Al ₂ O ₃ layer side. tool. 5. The surface-coated cutting according to claim 4, wherein at least one layer selected from the group of TiN, TiCN, TiC, TiCNO, TiCO, and TiNO is interposed between the stripe-like TiCN layers having the multilayer structure. tool. The surface-coated cutting tool according to claim 1, wherein the Al ₂ O ₃ layer has an α-type crystal structure.

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