JP6346066B2 - Cutting tool and manufacturing method - Google Patents

Description

  The present invention relates to a cutting tool, and more particularly, to a cutting tool having a coating layer excellent in fracture resistance and a method for manufacturing a cut product.

Cutting tools widely used for cutting of metals, printed circuit boards, etc. are known in which a single layer or a multilayer coating layer is formed on the surface of a substrate such as cemented carbide, cermet or ceramic. It has been. As this coating layer, a chemical vapor deposition (CVD) film in which a TiC (titanium carbide) layer, a TiN (titanium nitride) layer, a TiCN (titanium carbonitride) layer, an Al ₂ O ₃ (aluminum oxide) layer, etc. are laminated is often used. Has been.

For example, Patent Document 1 discloses a cutting insert in which a surface of a cemented carbide substrate is coated with a TiCN layer, an Al ₂ O ₃ layer, and a TiCN layer in this order. Patent Document 2 has a configuration in which the surface of a silicon nitride substrate is coated with a hard coating layer, and the first layer of the hard coating layer is a titanium nitride layer made of columnar particles including granular crystals having a crystal particle diameter of 1 to 30 nm. It is disclosed.

  Moreover, in patent document 3, the average particle diameter of the hard phase which exists in a skin surface by electropolishing is made smaller than the average particle diameter of the hard phase which exists inside, and the smoothness of a skin surface is improved. A cemented carbide is disclosed.

JP 2003-213455 A JP 10-015707 A JP 2000-265236 A

However, the structure of the coating layer in which the TiCN (TiN) layer and the Al ₂ O ₃ layer described in Patent Document 1 are repeatedly laminated, or a substrate made of a silicon nitride-based sintered body as in Patent Document 2 are provided. Even when the crystal form of the TiN layer to be formed is a structure in which granular particles and columnar particles are mixed in a portion adjacent to the substrate, the adhesion of the coating layer may be insufficient, and Al ₂ O during cutting may be insufficient. _In some cases, cracks occurred in the _three layers and the coating layer chipped. Even if the cemented carbide with the average particle size of the hard phase on the burned skin surface is reduced as in Patent Document 3, the smoothness of the burned skin surface is improved, but it is required to further improve the adhesion between the substrate and the coating layer. It was done.

The cutting tool of the present invention is a cutting tool comprising a base composed of a silicon nitride sintered body mainly containing silicon nitride particles, and a coating layer coated on the surface of the base,
In a cross section perpendicular to the surface of the substrate,
The silicon nitride particles are composed of surface particles that are present on the outermost surface of the substrate and are in contact with the coating layer, and internal particles that are not in contact with the coating layer, and are average particles parallel to the surface of the substrate. The ratio (w1 / w2) of the width w1 to the average particle width w2 of the internal particles parallel to the surface of the substrate is 0.2 to 0.6, and the average particle width w1 and average particles of the surface particles The ratio of the length L1 (L1 / w1) is 0.1 to 0.6, and among the particles constituting the coating layer, the particles constituting the first coating layer in contact with the substrate are The ratio (w1 / d1) of the average particle width d1 parallel to the surface to the average particle width w1 of the surface particles is 0.8 to 2.1.

  The manufacturing method of the cut workpiece of the present invention includes a step of rotating a workpiece, a step of bringing the cutting blade of the cutting tool into contact with the rotating workpiece, and the cutting tool as the workpiece. And a step of separating from.

  In the cutting tool of the present invention, the base is made of a silicon nitride sintered body, and the average particle width w1 of the surface particles in contact with the outermost coating layer is a ratio (w1 / w2) to the average particle width w2 of the internal particles. As small as 0.2 to 0.6. Moreover, the ratio (L1 / w1) of the average particle width w1 of the surface particles to the average particle length L1 is as wide as 0.1 to 0.6. Further, the ratio (w1 / d1) of the average particle width d1 of the first coating layer in contact with the substrate to the average particle width w1 of the surface particles in the coating layer is approximately 0.8 to 2.1. ing. Therefore, the adhesion between the substrate and the coating layer is good, and the impact received by the coating layer can be dispersed and transmitted to the substrate side, and the substrate has high impact resistance.

It is a scanning electron micrograph about the grinding | polishing cross section containing the coating layer of the cutting tool which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the cut workpiece in one embodiment of this invention, FIG. 2A, FIG. 2B, and FIG. 2C are schematic which shows the process in any one of this manufacturing method.

  As shown in FIG. 1, a cutting insert 1 which is a preferred example of a cutting tool includes a base 2 made of a silicon nitride sintered body mainly containing silicon nitride particles, and a coating layer 3 coated on the surface of the base 2. And.

  Here, in the present invention, containing silicon nitride particles as a main component means that silicon nitride particles are present at a ratio of 50 area% or more with respect to the area of the region in an arbitrary region of 10 μm or more × 10 μm or more of the substrate 2. Point to. The silicon nitride particles are composed of surface particles 4 which are present on the outermost surface of the substrate 2 and are in contact with the coating layer 3, and internal particles 5 which are not in contact with the coating layer 3.

  On the other hand, the coating layer 3 is composed of a single layer or a plurality of layers, and the first coating layer in contact with the surface particles 5 is present in the first layer 7 in contact with the substrate 2.

  In this embodiment, the ratio (w1 / w2) of the average particle width w1 of the surface particles 4 parallel to the surface of the substrate 2 to the average particle width w2 of the inner particles 5 parallel to the surface of the substrate 2 is 0.2. The ratio (L1 / w1) of the average particle width w1 and the average particle length L1 of the surface particles 4 is 0.1 to 0.6. The ratio (w1 / d1) of the average particle width d1 of the first coating layer of the first layer 7 to the average particle width w1 of the surface particles is 0.8 to 2.1.

  Accordingly, the adhesion between the base 2 and the coating layer 3 is good, and the impact received by the coating layer 3 can be distributed and transmitted to the base 2 side, and the impact resistance of the base 2 is high. That is, since the average particle diameters of the surface particles of the substrate 2 and the first coating layer of the coating layer 3 are approximate, even when the temperature rises and falls due to the influence of cutting heat, the shrinkage difference between the two is small and the adhesion is high. Moreover, since the ratio (L1 / w1) of the surface particles 4 is as wide as 0.1 to 0.6, the impact received by the coating layer 3 can be dispersed and transmitted to the substrate side, and the fracture resistance is improved. .

In the present invention, the average particle widths w1 and w2 of the surface particles 4 and the inner particles 5 are obtained by drawing a straight line parallel to the surface of the substrate 2 on a polished surface having a cross section perpendicular to the surface of the substrate 2. Measured by calculating the value divided by the number of grain boundaries crossing the straight line. The number of grain boundaries is measured in a range of 5 or more. The straight line for measuring the average particle width of the surface particles 4 is
It is measured at the outermost surface position of the surface particle 5 to be measured, that is, at the position where it comes into contact with the coating layer 3. The straight line for measuring the average particle width of the internal particles 5 is measured at three arbitrary positions deeper than the length L1 of the surface particles 5, and the average value is taken. In FIG. 1, straight lines for measuring w1, w2, L1, and d1 are indicated by dotted lines, respectively. The polished surface of the cross section may be smooth enough to observe the particles constituting the surface particles 4, the inner particles 5, and the coating layer 3, and may be confirmed with a scanning electron microscope. When the polishing powder fills the grain boundary between the particles and the grain boundary cannot be discriminated on the polished surface of 1, the orientation of each particle is confirmed by electron beam backscatter diffraction (EBSD), and the orientation is different. At the boundary, it is assumed that there are two particles, and the average particle size of the particles is produced on the side.

  In the polished surface of FIG. 1, the average aspect ratio of the internal particles 5 is 1.5 or more. Thereby, the toughness of the base body 2 is high, and the chipping resistance of the cutting insert 1 is improved. A desirable range of the average aspect ratio of the inner particles 5 is 1.7 to 3.0. In the present invention, the average aspect ratio of the inner particles 5 is the ratio of the major axis that is the longest length of the inner particles 5 to the minor axis that is the longest length in the direction perpendicular to the major axis on the polished surface ( (Major axis / minor axis). In this embodiment, the average major axis, which is the average of the major axes of the inner particles 5, is 0.5 to 3.0 μm. Thereby, the chipping resistance of the cutting insert 1 can be improved. A desirable range of the average major axis of the inner particles 5 is 1.5 to 2.0 μm.

On the other hand, the coating layer 3 includes a first layer 7 made of TiN having an average particle width of 0.1 to 0.4 μm and Al ₂ having an average particle width of 0.01 to 1.5 μm from the substrate 2 side. The second layer 8 composed of O ₃ and the third layer 9 composed of TiN having an average particle width of 0.01 to 0.1 μm and an average particle width smaller than the average particle width of the first layer 7. A fourth layer 10 composed of Al ₂ O ₃ having an average particle width of 0.01 to 1.5 μm and TiC _x N ₁₋ composed of an average particle width of 0.01 to 0.7 μm. The fifth layer 11 made of TiC with _x (0 ≦ x ≦ 1), particularly x = 1, is laminated in this order. Desirable ranges of the average particle width are as follows: the first layer 7 is 0.2 to 0.3 μm, the second layer 8 is 0.4 to 1.0 μm, the third layer 9 is 0.01 to 0.05 μm, and the fourth layer. 10 is 0.3 to 1.0 μm, and the fifth layer 11 is 0.2 to 0.5 μm.

  Since the silicon nitride sintered body constituting the substrate 2 is made of needle-like particles, relatively large irregularities are formed on the surface of the substrate 2. However, in the cutting insert 1, the surface of the base body 2 may be polished in order to increase the dimensional accuracy. In such a case, the unevenness of the surface of the substrate 2 is reduced and the smoothness is improved, but the adhesion with the coating layer 3 is lowered. For this purpose, in this embodiment, the properties of the surface particles of the substrate 2 are improved, and the first layer 7 having a particle size close to that of the surface particles 6 of the substrate 2 is formed immediately above the substrate 2.

In the present embodiment, the first layer 7 is composed of a TiN layer. Thereby, the adhesiveness of the coating layer 3 is high. Next, in order to improve the wear resistance of the coating layer 3, a second layer 8 made of Al ₂ O ₃ is formed on the surface of the first layer 7. Then, a third layer 9 made of TiN having an average particle width of 0.01 to 0.1 μm smaller than the average particle width of the first layer 7 is formed on the surface of the second layer 8. The third layer 9 relieves an impact applied to a fourth layer 10 to be described later, and suppresses occurrence of cracks in the Al ₂ O ₃ layers of the fourth layer 10 and the second layer 8. Further, a fourth layer 10 made of Al ₂ O ₃ is laminated on the surface of the third layer 9 in order to improve the wear resistance of the coating layer 3. A fifth layer 11 is provided on the surface of the fourth layer 10 in order to change the color of the coating layer 3 so that the usage state of the cutting insert 1 can be easily understood, and to suppress welding of the work material.

  With the configuration of the coating layer 3, the coating layer 3 having high adhesion between the base 2 and the coating layer 3 and high fracture resistance is obtained, and the wear resistance and fracture resistance of the cutting insert 1 are improved. The first layer 7 is made of columnar particles having an aspect ratio of 2 to 10, and the third layer 9 is made of granular particles having an aspect ratio of 1.5 or less.

  In this embodiment, the orientation of the particles constituting the first layer 7, the second layer 8, the third layer 9, the fourth layer 10 and the fifth layer 11 to a specific crystal plane is determined by an electron beam backscatter diffraction method ( EBSD), but the organization coefficient is 0.8 to 1.2, there is no orientation to a specific crystal plane, and there is no orientation. Thereby, the fracture resistance of the coating layer 3 is increased.

  Furthermore, in this embodiment, the ratio (d3 / d1) between the average particle width d1 of TiN constituting the first layer 7 and the average particle width d3 of TiN constituting the third layer 9 is 0.05 to 0.00. 7. As a result, the adhesion between the substrate 2 and the coating layer 3 can be enhanced, and the chipping resistance of the coating layer 3 can be enhanced.

(Production method)
One embodiment of the manufacturing method of the cutting insert mentioned above is described. As starting materials, silicon nitride (Si ₃ N ₄ ) powder having an average particle size of 0.2 to 0.8 μm and rare earth element (Re) compound (lanthanum hydroxide (La ( OH) ₂ ), yttrium oxide (Y ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), erbium oxide (Er ₂ O ₃ ), cerium oxide (Ce ₂ O ₃ )) powder and average particle diameter A 0.2 to 0.8 μm aluminum oxide (Al ₂ O ₃ ) powder and a magnesium hydroxide (Mg (OH) ₂ ) powder having an average particle size of 1.8 to 4.0 μm are mixed, and press-molded and cast. A predetermined tool shape is formed by a known forming method such as insert molding, extrusion molding, or cold isostatic pressing.

When this molded body is degreased and then set in a baking pot, it is set using a mixed powder of at least one of Si ₃ N ₄ powder, Si powder, and SiO ₂ powder and Mg (OH) ₂ powder, and the lid This is placed in a firing furnace in a state of being placed in a carbon cylinder. Then, the inside of the firing furnace is replaced with 1 atm (101 kPa) of nitrogen, the temperature is increased to 1200 ° C. at a rate of temperature increase of 5 to 15 ° C./min, and then the temperature is increased to 1840 to 1880 ° C. at 1 to 5 ° C./min. Thereafter, the furnace is cooled for 1 to 4 hours in an atmosphere of 1900 to 1950 ° C. and 5 to 10 atmospheres of nitrogen (505 kPa to 1013 kPa). And if desired, hot isostatic pressing (HIP treatment) is performed under conditions of 1500 to 1700 ° C., 2 to 5 hours, and 170 to 220 MPa to obtain a silicon nitride sintered body. Then, if desired, thickness grinding processing (double-head processing and peripheral processing) is performed on the surface of the sintered body, and honing processing is performed on the cutting edge portion.

Then, a coating layer is formed on the surface by chemical vapor deposition (CVD). When forming a film, the processed substrate is set in a film formation chamber, and hydrogen (H ₂ ) gas is introduced at a pressure of 10 kPa to 100 kPa, so that the film formation temperature is 20 to 50 higher than the film formation temperature of the first layer. Raise the temperature to a higher temperature. By this step, decomposition of the silicon nitride particles present on the surface of the substrate can be promoted, and the shape of the silicon nitride particles can be changed within a predetermined range.

Next, as a reaction gas composition, a mixed gas composed of titanium chloride (TiCl ₄ ) gas of 1 to 5% by volume, nitrogen (N ₂ ) gas of 10 to 60% by volume, and the remainder of hydrogen (H ₂ ) gas is adjusted. The first layer (TiN layer) is formed under the condition of 10 kPa to 20 kPa while being introduced into the reaction chamber and the film formation temperature is lowered from the temperature of the above process to the film formation temperature of 970 to 1050 ° C. At this time, the diffusion ratio of each element in the vicinity of the interface between the substrate and the first layer can be controlled by adjusting the film formation temperature and the gas pressure of the first layer. Whether the TiN particles are columnar or granular can be adjusted by changing the film forming temperature and the pressure of the mixed gas.

Next, a second layer (Al ₂ O ₃ layer) is formed. As a method for forming the Al ₂ O ₃ layer, ₃ to 20% by volume of aluminum chloride (AlCl ₃ ) gas, 0.5 to 10% by volume of hydrogen chloride (HCl) gas, and 0 of carbon dioxide (CO ₂ ) gas are used. It is desirable to use a mixed gas composed of 0.01 to 20% by volume and the remainder consisting of hydrogen (H ₂ ) gas, 960 to 1100 ° C., 5 to 25 kPa,
Under these conditions, κ-Al ₂ O ₃ is basically produced, but α-Al ₂ O ₃ may be produced in some cases.

Further, the reaction gas composition is adjusted by adjusting a mixed gas composed of 1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 10 to 60% by volume of nitrogen (N ₂ ) gas, and the remaining hydrogen (H ₂ ) gas. It introduce | transduces in a chamber and forms a 3rd layer (TiN layer) on the conditions whose film-forming temperature is 900-950 degreeC and 10-50 kPa.

Subsequently, a fourth layer (Al ₂ O ₃ layer) is formed. As a method for forming the Al ₂ O ₃ layer, ₃ to 20% by volume of aluminum chloride (AlCl ₃ ) gas, 0.5 to 10% by volume of hydrogen chloride (HCl) gas, and 0 of carbon dioxide (CO ₂ ) gas are used. It is desirable to use a mixed gas composed of 0.01 to 20.0% by volume and the remainder consisting of hydrogen (H ₂ ) gas, and 950 to 1100 ° C. and 5 to 25 kPa. Under these conditions, κ-Al ₂ O ₃ is generated. However, α-Al ₂ O ₃ may be generated.

Thereafter, on the outermost surface, for example, as a reaction gas composition, titanium chloride (TiCl ₄ ) gas is 0.1 to 10% by volume, carbon dioxide (CO ₂ ) gas is 0.01 to 10% by volume, and the remainder is volume%. A mixed gas composed of hydrogen (H ₂ ) gas is adjusted and introduced into the reaction chamber, and a fifth layer composed of TiC is formed under the conditions of a film formation temperature of 780 to 1100 ° C. and 5 to 25 kPa, and silicon nitride A cutting insert having a coating layer formed on the surface of the sintered material is obtained.

  Then, if desired, at least the cutting edge portion on the surface of the formed coating layer 3 is polished. By this polishing process, the cutting edge portion is processed smoothly, the welding of the work material is suppressed, and the tool is further excellent in fracture resistance.

(Manufacturing method of cut product)
The manufacturing method of the cut workpiece in this embodiment is demonstrated in detail, referring FIG. FIG. 2A is a diagram illustrating a process of bringing the cutting tool 41 having the cutting insert 1 mounted in the insert pocket 46 of the holder 42 closer to the work material 50 in the Y direction. FIG. 2B is a diagram illustrating a process of bringing the cutting tool 41 into contact with the work material 50. FIG. 2C is a diagram illustrating a process of separating the cutting tool 41 from the work material 50 in the Z direction.

The manufacturing method of the cut workpiece in this embodiment includes the following steps (i) to (iV). (I) The process of arrange | positioning the cutting tool 41 above the prepared workpiece 50 (FIG. 2A).
(Ii) A step of rotating the work material in the direction of the arrow r about the rotation axis O to bring the cutting tool 41 closer to the work material 50 (FIG. 2A). This step is performed, for example, by fixing the work material 50 on a table of a machine tool to which the cutting tool 41 is attached and bringing the cutting tool 41 closer to the work material 50 in a state where the work material 50 is rotated. be able to. In this step, the work material 50 and the cutting tool 41 may be relatively close to each other. For example, the work material 50 may be brought close to the cutting tool 41 by fixing the cutting tool 41.

(iii) By bringing the cutting tool 41 closer to the work material 50, the cutting edge 2 of the cutting tool 41 is brought into contact with a predetermined position on the surface of the rotating work material 50, so that the work material 50 is moved. Step of cutting (FIG. 2B).

  (Iv) A step of separating the cutting tool 41 from the through hole 51 of the work material 50 (FIG. 2C). Also in this step, similarly to the step (ii), the work material 50 and the cutting tool 41 may be relatively separated from each other. For example, the cutting tool 41 is fixed and the work material 50 is removed from the cutting tool 41. May be separated from

Through the above steps, excellent cutting performance can be exhibited. In the case of repeatedly performing the cutting process, the step of bringing the cutting blade 2 of the cutting tool 41 into contact with a different part of the work material 50 while keeping the rotation of the work material 50 may be repeated.

As starting materials, 1.76% by mass of lanthanum hydroxide (La (OH) ₂ ) powder as an Re element compound having an average particle size of 1.2 μm and aluminum oxide (Al ₂ O ₃ ) powder having an average particle size of 0.7 μm 0.4 mass%, 0.72 mass% of magnesium hydroxide (Mg (OH) ₂ ) powder having an average particle diameter of 2.5 μm, and the balance of silicon nitride (Si ₃ N ₄ having an average particle diameter of 0.3 μm) ) After mixing with a powder and adding a binder and a solvent, the mixture was pulverized and mixed in a mill for 72 hours. Thereafter, the solvent was removed by drying to prepare a granulated powder, and this granulated powder was press-molded into a cutting tool shape of SNGN120212 at a pressure of 98 MPa.

After degreasing, when this molded body is set in a baking pot, the molded body is filled with a mixed powder of Si ₃ N ₄ powder, Si powder and Mg (OH) ₂ powder as a spread powder around the molded body. It was placed and covered, and placed in a firing furnace in a state where it was placed in a carbon cylinder. Then, the inside of the firing furnace was replaced with 101 kPa (1 atm) of nitrogen, the temperature was increased to 1200 ° C. at a rate of temperature increase of 10 ° C./min, and then the temperature was increased to 1860 ° C. at 2 ° C./min. Thereafter, the furnace was cooled for 2 hours in an atmosphere of 1920 ° C. and nitrogen at 909 kPa (9 atm). Thereafter, hot isostatic pressing (HIP) is performed at 1600 ° C. for 2 hours and 196 MPa, and the surface of the sintered body is further subjected to 0.3 mm thickness grinding (double-head processing and peripheral processing) to sinter silicon nitride. Got the body. The cross-section of the silicon nitride sintered body was observed for a structure at a magnification of 5000 using a scanning electron microscope (SEM), and the average particle diameter of the silicon nitride particles was measured by image analysis. The result was 0.6 μm.

Next, a coating layer was formed on the surface by chemical vapor deposition (CVD). The film formation conditions were the pretreatment conditions shown in Tables 1 and 3, and then each layer was formed under the conditions shown in Table 1. Sample No. The film formation conditions of the first coating layer are as follows: the first TiN layer is formed using the mixed gas composition of TiN2 in Table 1 at a film formation temperature of 1010 ° C. and a gas pressure of 15 kPa. The Al ₂ O ₃ layer was formed using the Al ₂ O ₃ 1 mixed gas composition shown in Table 1 at a film forming temperature of 1005 ° C. and a gas pressure of 9 kPa, and the third TiN layer was TiN 1 of Table 1. Using the mixed gas composition, the film formation temperature is 920 ° C. and the gas pressure is 30 kPa, and the Al ₂ O ₃ layer of the fourth layer uses the mixed gas composition of Al ₂ O ₃ 2 in Table 1. The film was formed at a film formation temperature of 1005 ° C. and a gas pressure of 9 kPa. The fifth TiC layer was formed at a film formation temperature of 1010 ° C. and a gas pressure of 15 kPa using the TiC mixed gas composition shown in Table 1. Filmed. Sample No. For 2-17, a TiN layer of the first layer in TiN2 in Table 1, the _{the Al} 2 _{O 3} layer of the second layer with _Al 2 _{O 3} 1 of Table 1, TIN1 in Table 1 a TiN layer of the third layer in the _{the Al} 2 _{O 3} layer of the fourth layer in the _Al 2 _{O 3} 2 of Table 1, and the fifth layer is deposited using any of the conditions listed in Table 1 of TiC, TiCN or TIN2. Then, the surface of the coating layer 3 was brushed for 30 seconds from the rake face side, and sample No. 1 to 17 cutting tools were produced.

  And the average particle width was measured about the surface particle | grains and internal particle | grains of a base | substrate using the scanning electron microscope (SEM) and EBSD analysis. Moreover, the average particle length was measured for the surface particles, and the aspect ratio was measured for the internal particles. The results are shown in Table 2. Furthermore, for each layer of the coating layer, the form, thickness, and average particle width of the particles constituting each layer were measured. Further, the aspect ratio of the columnar particles was measured. The results are shown in Table 3.

Furthermore, using this cutting tool, an intermittent cutting test was performed under the following conditions to evaluate fracture resistance.
Workpiece material: FCD-450 Sleeve material Cutting speed: 500 m / min Feed amount: 0.5 mm / rev
Cutting depth: 2.0mm
Cutting conditions: Wet cutting evaluation items: After machining for 10 minutes, the flank wear amount and chipping state of the cutting blade were observed with a digital scope. The results are shown in Table 3.

  Sample No. with a w1 / w2 ratio greater than 0.6. In 15, the coating layer was peeled off. In addition, the sample No. w / w2 ratio is smaller than 0.2. In No. 16, chipping occurred in the coating layer. Further, sample No. 1 with an L1 / w1 ratio exceeding 0.6 was obtained. In No. 14, the cutting edge was damaged. Sample No. with a w1 / d1 ratio exceeding 2.1 was obtained. In 17, the coating layer peeled off.

On the other hand, sample No. having a coating layer structure according to the present invention. In Nos. 1 to 13, there was no chipping or peeling of the coating layer, and the flank wear amount was small. Among them, Sample No. with an average aspect ratio of internal particles of 1.5 or more. In 1-3, 5-13, the amount of wear was small. Further, the coating layer is, from the substrate side, a first layer of TiN, a second layer of _Al 2 _{O 3,} a third layer consisting of TiN, and a fourth layer of _Al 2 _{O 3,} from TiC Sample No. consisting of the fifth layer. In 1-3, 5, and 7-13, there was a tendency for the amount of wear to become small. Further, the first layer is made of columnar particles having an aspect ratio of 2 to 10, and the third layer is made of Sample No. 2 made of granular particles having an aspect ratio of 1.5 or less. In 1 to 5, 9, and 13, the wear amount tended to be small. The thickness of the first layer is 0.7 to 1.3 μm, the thickness of the second layer is 0.5 to 1.2 μm, the thickness of the third layer is 0.1 to 0.3 μm, and the thickness of the fourth layer is Sample No. 5 having a thickness of 0.5 to 1.2 μm and a fifth layer having a thickness of 0.1 to 0.5 μm. In 1, 2, 3, 5, 8, and 13, the amount of wear tended to be small. Furthermore, the sample No. 1 in which the ratio (d3 / d1) of the average particle width d1 of TiN constituting the first layer to the average particle width d3 of TiN constituting the third layer is 0.05 to 0.7. 1 to 11 tended to reduce the wear amount.

DESCRIPTION OF SYMBOLS 1 Cutting insert 2 Base | substrate 3 Coating layer 4 Surface particle 5 Internal particle 7 1st layer (TiN layer)
8 Second layer (Al ₂ O ₃ layer)
9 Third layer (TiN layer)
10 Fourth layer (Al ₂ O ₃ layer)
11 Fifth layer (TiC _x N _1-x layer)

Claims (8)

A cutting tool comprising a base composed of a silicon nitride sintered body mainly containing silicon nitride particles, and a coating layer coated on the surface of the base,
In a cross section perpendicular to the surface of the substrate,
The silicon nitride particles are composed of surface particles that are present on the outermost surface of the substrate and are in contact with the coating layer, and internal particles that are not in contact with the coating layer, and are average particles parallel to the surface of the substrate. The ratio (w1 / w2) of the width w1 to the average particle width w2 of the internal particles parallel to the surface of the substrate is 0.2 to 0.6, and the average particle width w1 and average particles of the surface particles The ratio (L1 / w1) to the length L1 is 0.1 to 0.6, and among the particles constituting the coating layer, the first coating layer in contact with the substrate is parallel to the surface of the substrate. The cutting tool whose ratio (w1 / d1) of the average particle width d1 and the average particle width w1 of the said surface particle is 0.8-2.1. In vertical cross section on the surface of the substrate, cutting tool according to claim 1, wherein the average aspect ratio of the inner particle is 1.5 or more.   The cutting tool according to claim 1 or 2, wherein the coating layer includes a plurality of layers, and the first layer including the first coating layer of the base includes a TiN layer.   The coating layer includes, from the substrate side, the first layer made of TiN, the second layer made of Al 2 O 3, the third layer made of TiN, the fourth layer made of Al 2 O 3, and the fifth layer made of TiC. The cutting tool according to claim 3, comprising:   The cutting tool according to claim 4, wherein the first layer is made of columnar particles having an aspect ratio of 2 to 10, and the third layer is made of granular particles having an aspect ratio of 1.5 or less.   The thickness of the first layer is 0.7 to 1.3 μm, the thickness of the second layer is 0.5 to 1.2 μm, the thickness of the third layer is 0.1 to 0.3 μm, The cutting tool according to claim 4 or 5, wherein the thickness is 0.5 to 1.2 µm, and the thickness of the fifth layer is 0.1 to 0.5 µm.   The ratio (d3 / d1) between the average particle width d1 of TiN constituting the first layer and the average particle width d3 of TiN constituting the third layer is 0.05 to 0.7. 6. The cutting tool according to any one of 6. A step of rotating the workpiece, a step of bringing the cutting blade of the cutting tool according to any one of claims 1 to 7 into contact with the rotating workpiece, and separating the cutting tool from the workpiece. A method of manufacturing a cut product including a process.