Covered tool and cutting tool having the same

Abstract

The covering tool disclosed in the present invention comprises a substrate and a covering layer located on the surface of the substrate. The covering layer comprises an Al2O3 layer and an intermediate layer containing Ti. The Al2O3 layer is arranged in contact with the intermediate layer at a position farther away from the substrate than the intermediate layer. The intermediate layer has a plurality of first protrusions protruding toward the Al2O3 layer. At least one of the plurality of first protrusions is a composite protrusion having a second protrusion protruding in a direction intersecting with the protruding direction of the first protrusion. The proportion of the composite protrusions in the plurality of first protrusions is less than 30%. The cutting tool disclosed in the present invention comprises: a bracket extending from a first end toward a second end and having a recess on the first end side; and the above-mentioned covering tool located in the recess.

Description

Technical Field

[0001] The present disclosure relates to a covered tool having a covering layer on the surface of a base body and a cutting tool including the covered tool. Background Art

[0002] There is known a covered tool such as a cutting tool in which a covering layer is formed on the surface of a base body such as a cemented carbide, a cermet, or a ceramic, and an Al 2 O 3 layer is laminated on the covering layer via a bonding film.

[0003] As cutting processing becomes more efficient recently, cutting tools are increasingly used in heavy intermittent cutting, which imposes a large impact on the cutting edge. Under such severe cutting conditions, a large impact is imposed on the covering layer, which is prone to chipping and peeling. Therefore, in addition to wear resistance, the covering layer is also required to have improved defect resistance.

[0004] In order to solve such a problem, Patent Document 1 describes that a protrusion having a tip bent into a hook shape is arranged at an interface with an Al 2 O 3 layer.

[0005] Furthermore, Patent Documents 2 and 3 describe that a composite protrusion having a plurality of second protrusions is arranged on the side surface of a first protrusion extending along the stacking direction of the covering layer at an interface with an Al 2 O 3 layer.

[0006] Among them, the protrusions and composite protrusions described in Patent Documents 1 and 2 have obtuse front ends and are in a shape with poor film-forming properties. In addition, the composite protrusions described in Patent Documents 2 and 3 do not have first protrusions, but only composite protrusions, and are also in a shape with poor film-forming properties.

[0007] Prior Art Literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2004-74324

[0010] Patent Document 2: U.S. Patent Publication No. 2013 / 0149527

[0011] Patent Document 3: Japanese Patent Application Publication No. 2009-166216 Summary of the invention

[0012] -Problems to be solved by the invention-

[0013] Provided is a covering tool having excellent defect resistance.

[0014] -Methods for solving problems-

[0015] The covering tool disclosed in the present invention comprises a substrate and a covering layer located on the surface of the substrate. The covering layer comprises an Al2O3 layer and an intermediate layer containing Ti. The Al2O3 layer is arranged in contact with the intermediate layer at a position farther from the substrate than the intermediate layer. The intermediate layer comprises a plurality of first protrusions protruding toward the Al2O3 layer. At least one of the plurality of first protrusions is a composite protrusion having a second protrusion protruding in a direction intersecting with the protruding direction of the first protrusion. The proportion of the composite protrusions in the plurality of first protrusions is less than 30%.

[0016] The cutting tool disclosed in the present invention comprises: a support extending from a first end toward a second end and having a recess on the first end side; and the above-mentioned covering tool located in the recess. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic perspective view showing an example of the covering tool of the present disclosure.

[0018] Figure 2 It is used to illustrate Figure 1 Schematic diagram of the structure of a cross section of a covering layer in a covering tool.

[0019] Figure 3 This is an enlarged view of main parts for explaining the structure of the intermediate layer and the vicinity of the Al2O3 layer of the covering tool of the present disclosure.

[0020] Figure 4 This is an enlarged view of main parts for explaining the structure of the intermediate layer and the vicinity of the Al2O3 layer of the covering tool of the present disclosure.

[0021] Figure 5 It is a top view showing an example of the cutting tool of the present disclosure. DETAILED DESCRIPTION

[0022] <Overwrite Tool>

[0023] exist Figure 1 In the example shown, the main surface of the covering tool disclosed in the present invention is a roughly quadrilateral plate. However, it is not limited to this shape. The covering tool 1 has a first surface 2 and a second surface 3, and has a cutting edge 4 at least in a portion where the first surface 2 and the second surface 3 intersect. The first surface 2 is a surface called a front cutting surface, and the second surface 3 is a surface called a back cutting surface. Therefore, it can also be said that at least a portion where the front cutting surface 2 and the back cutting surface 3 intersect has a cutting edge 4.

[0024] In addition, if Figure 2 As shown in the schematic diagram for explaining the cross-sectional structure of the coating layer 7 in the coating tool 1 , the coating tool 1 includes a base 5 and a coating layer 7 located on the surface of the base 5 .

[0025] The material of the substrate 5 constituting the covering tool 1 may be cemented carbide, ceramic or metal. As cemented carbide, tungsten carbide (WC), cobalt (C o ), nickel (Ni) and other iron-containing superhard alloys. Other hard alloys may also include titanium carbonitride (TiCN), cobalt (C o ), Ti-based cermets of iron group metals such as nickel (Ni). Ceramics can be Si3N4, Al2O3, diamond, cubic boron nitride (cBN). As metal, it can also be carbon steel, high-speed steel, alloy steel. Among the above materials, when used as a covering tool 1, it is preferable that the substrate 5 is composed of superhard alloy or cermet from the aspects of defect resistance and wear resistance.

[0026] The cover layer 7 includes an Al 2 O 3 layer 11 and an intermediate layer 9 containing Ti. The Al 2 O 3 layer 11 is in contact with the intermediate layer 9 at a position of the intermediate layer 9 that is away from the substrate 5 .

[0027] The intermediate layer 9 in the cover tool 1 of the present disclosure is a layer containing Ti, and may contain TiN, TiC, TiNO, etc., for example. In addition, for example, it may contain Ti, C, and N. In other words, the intermediate layer 9 may also contain TiCN crystals. In addition, the intermediate layer 9 may also contain Ti, C, N, and O, for example. In other words, the intermediate layer 9 may also contain TiCNO crystals. With such a structure, the Al2O3 layer 11 and the intermediate layer 9 have excellent adhesion.

[0028] like Figure 3 As shown, the capping tool 1 of the present disclosure has a plurality of first protrusions 13 protruding toward the Al 2 O 3 layer 11 .

[0029] The first protrusion 13 has a bottom 13a as a protruding start point of the first protrusion 13. In addition, the first protrusion 13 has a front end 13b at a position farthest from the base 5. In other words, the first protrusion 13 extends from the bottom 13a toward the front end 13b. The first protrusion 13 typically has a triangular shape.

[0030] The bottom (base) 13a refers to the position of the first protrusion 13 close to the base 5. The bottom 13a may also be referred to as the base of the triangle formed by the first protrusion 13.

[0031] In addition, in the covering tool 1 of the present disclosure, as Figure 3 , 4 As shown, the front end 13b of the first protrusion 13 is acute-angled and has a height of 10 nm or more, and the ratio of the average height of the plurality of first protrusions 13 to the average width of the bottom 13a of the plurality of first protrusions 13 is 0.6 or more.

[0032] like Figure 3As shown, in the covering tool 1 of the present disclosure, at least one of the plurality of first protrusions 13 is a composite protrusion 17 having a second protrusion 15 protruding in a direction intersecting with the protruding direction of the first protrusion 13. In the covering tool 1 of the present disclosure, all the first protrusions 13 may be composite protrusions 17. Hereinafter, the protrusion having the second protrusion 15 among the first protrusions 13 is referred to as a composite protrusion 17.

[0033] like Figure 3 As shown, the composite protrusion 17 in the covering tool 1 of the present application means that the bottom of the second protrusion 15 is separated from the bottom of the first protrusion 13. In other words, the structure in which a plurality of first protrusions 13 overlap is not treated as a composite protrusion 17.

[0034] In addition, the second protrusion 15 in the coating tool 1 of the present disclosure refers to a protrusion having a height of 10 nm or more from the center of the bottom 15a of the second protrusion 15, which is the protrusion starting point of the second protrusion 15, to the front end 15b of the second protrusion 15. In other words, the minute concavoconvexities existing on the side surface of the first protrusion 13 are not treated as the second protrusion 15 in the coating tool 1 of the present disclosure.

[0035] In the coating tool 1 of the present application, the proportion of the composite protrusions 17 in the plurality of first protrusions 13 is less than 30%. Figure 3 In the embodiment, there are 7 first protrusions, 2 of which are composite protrusions 17. In this case, the composite protrusions 17 account for 28.6% of the plurality of first protrusions 13. With such a structure, the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is excellent.

[0036] The ratio of the composite protrusions 17 to the plurality of first protrusions 13 may be 5% or more. In addition, the ratio of the composite protrusions 17 to the plurality of first protrusions 13 may be 20% or less.

[0037] The number of the first protrusions 13 and the compound protrusions 17 can be measured by, for example, taking a photograph at 30,000 times magnification using a scanning electron microscope or a transmission electron microscope. The proportion of the compound protrusions 17 in the plurality of first protrusions 13 can be measured for about 50 to 100 first protrusions 13. The number of photographs taken can be appropriately determined according to the number of compound protrusions 17 present. In addition, other structural elements in the covering tool disclosed in the present invention can also be measured in the same manner.

[0038] In the coating tool 1 of the present disclosure, the average number of the second protrusions 15 of the composite protrusions 17 is 1.2 or less. In addition, the average number of the second protrusions 15 of the composite protrusions 17 may be the average value of 50 composite protrusions 17. With such a structure, the film forming property of the Al2O3 layer 11 is excellent, and the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is excellent. In addition, since the composite protrusions 17 include the second protrusions 15, the lower limit of the average number does not include 1.

[0039] The ratio of the average height of the second protrusions 15 to the average width of the bottom 15a of the second protrusions 15 in the coating tool 1 of the present disclosure may be greater than the ratio of the average height of the plurality of first protrusions 13 to the average width of the bottom 13a of the plurality of first protrusions 13. In addition, the ratio of the average height of the second protrusions 15 to the average width of the bottom 15a of the second protrusions 15 refers to the value obtained by dividing the average height from the center of the bottom 15a of the second protrusions 15 to the front end 15b of the second protrusions 15 by the average width of the bottom 15a of the second protrusions 15. With such a structure, the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is more excellent.

[0040] In the coated tool 1 of the present disclosure, the ratio of the average height of the plurality of first protrusions 13 to the average width of the bottoms 13a of the plurality of first protrusions 13 may be 1.2 or less. With such a structure, the intermediate layer 9 and the Al2O3 layer 11 have excellent adhesion.

[0041] The ratio of the average height of the plurality of first protrusions 13 to the average width of the bottoms 13 a of the plurality of first protrusions 13 may be 1.0 or less.

[0042] In the coating tool 1 of the present disclosure, the average width of the bottom 13a of the first protrusion 13 is greater than 10nm and less than 50nm, and the average height of the first protrusion 13 can be greater than 10nm and less than 60nm. With such a structure, the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is excellent. In addition, the average width of the bottom 13a can also be greater than 25nm and less than 45nm. The average height of the first protrusion 13 can be greater than 10nm and less than 50nm.

[0043] In the covering tool 1 of the present disclosure, the average angle of the front end 13b of the first protrusion 13 can be greater than 50° and less than 90°. If such a structure is provided, the film forming property of the Al2O3 layer 11 is excellent, and the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is excellent. In addition, the average angle of the front end 13b of the first protrusion 13 can also be greater than 55°. In addition, the average angle of the front end 13b of the first protrusion 13 can also be less than 80°. If such a structure is provided, the film forming property of the Al2O3 layer 11 is excellent, and the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is more excellent.

[0044] In addition, if Figure 4 As shown, the composite protrusion 17 in the covering tool 1 of the present disclosure may also have a third protrusion 19 protruding in a direction intersecting with the protruding direction of the second protrusion 15. If such a structure is provided, the adhesion between the intermediate layer 9 and the Al2O3 layer 11 is more excellent. In addition, the height of the third protrusion 19 is greater than 10nm. In other words, the tiny asperities existing on the side of the second protrusion 15 are not treated as the third protrusion 19 in the covering tool 1 of the present disclosure. Such tiny asperities do not substantially contribute to the adhesion between the intermediate layer 9 and the Al2O3 layer 11.

[0045] In the covering tool 1 of the present disclosure, as Figure 4 As shown, the covering layer 7 may also have a TiN layer 10a, a first TiCN layer 10b, a second TiCN layer 10c, an intermediate layer 9 and an Al2O3 layer 11 in order from the substrate 5. If it has such a structure, it becomes a covering tool 1 with a long life. The first TiCN layer 10b may also be the MT-TiCN layer described later. The second TiCN layer 10c may also be the HT-TiCN layer described later. In addition, a TiN layer or the like may also be provided as a surface layer (not shown). The surface layer may also be made of other materials other than titanium nitride, such as titanium carbonitride, titanium carbonate nitride, chromium nitride, etc. The surface layer is composed of a colored material, and may also have the function of easily distinguishing whether a cutting edge is used. The surface layer may also be provided with a thickness of 0.1 μm to 3.0 μm.

[0046] The first protrusion 13, the second protrusion 15, and the third protrusion 19 in the cover tool 1 of the present disclosure all contain Ti, C, and N, and the composition can be homogeneous. In addition, the first protrusion 13, the second protrusion 15, and the third protrusion 19 all contain Ti, C, N, and O, and the composition can also be homogeneous. If the composition of the first protrusion 13, the second protrusion 15, and the third protrusion 19 is homogeneous, cracks and damage are not easy to occur between the first protrusion 13, the second protrusion 15, and the third protrusion 19, and the adhesion between the intermediate layer 9 and the Al2O3 layer 11 becomes higher than when the respective compositions are different.

[0047] In addition, the homogeneous composition of the first protrusions 13 , the second protrusions 15 , and the third protrusions 19 means that the difference in the respective structural components is 5% or less.

[0048] Furthermore, the deviation of the respective compositions may be 3% or less, or further, 1% or less.

[0049] Such first protrusions 13 , second protrusions 15 , and third protrusions 19 can be obtained by using the same gas when forming the first protrusions 13 , second protrusions 15 , and third protrusions 19 .

[0050] Furthermore, the first protrusion 13 and the second protrusion 15 may have different compositions, and the second protrusion 15 and the third protrusion 19 may have different compositions.

[0051] In order to form the first protrusions 13 , the second protrusions 15 , and the third protrusions 19 having different compositions, gases having different compositions may be used during film formation.

[0052] Furthermore, the first protrusions 13 may not be formed perpendicularly to the first surface 2 of the base 5 , but may be formed inclined relative to the first surface 2 of the base 5 .

[0053] When the thickness of the intermediate layer 9 is 10 nm to 35 nm, the hardness of the intermediate layer 9 does not decrease, and the Al2O3 layer 11 has an α-type crystal structure. Here, the thickness of the intermediate layer 9 refers to the thickness excluding the first protrusions 13, the second protrusions 15, and the third protrusions 19.

[0054] The intermediate layer 9 may contain titanium at a ratio of 30 to 70 atomic %, carbon at a ratio of 1 to 70 atomic %, nitrogen at a ratio of 1 to 35 atomic %, and oxygen at a ratio of 3 to 20 atomic %. In addition, it may further contain aluminum at a ratio of 10 atomic % or less. In addition, it may also contain chlorine, chromium, and other components at a ratio of 1 to 10 atomic %. In addition, the intermediate layer 9 may also contain other trace components.

[0055] In the coating tool 1 of the present disclosure, the first protrusions 13 , the second protrusions 15 , and the third protrusions 19 may all have the same composition, or may have the composition range described above.

[0056] <Manufacturing method>

[0057] The intermediate layer having the first protrusions can be formed, for example, by forming a film on the surface of the substrate by a chemical vapor deposition (CVD) method under the following conditions.

[0058] First, the substrate is arranged in the chamber of the film forming device, for example, the film forming temperature is set to 900°C to 990°C, the gas pressure is set to 15kPa to 40kPa, and the reaction gas composition is set as follows to form the film: titanium tetrachloride (TiCl4) gas is set to 3% to 15% by volume, methane (CH4) gas is set to 3% to 10% by volume, nitrogen (N2) is set to 3% to 50% by volume, carbon monoxide (CO) gas is set to 0.2% to 1.0% by volume, and the remaining component is hydrogen (H2) gas. For convenience, this process is called the early process of the film forming process of the intermediate layer. The film forming time of this early process can be more than 20 minutes and less than 40 minutes. If the nitrogen (N2) gas of the reaction gas composition is set to 30% to 50% by volume, the average width of the bottom of the first protrusion is easy to widen, and the average height of the first protrusion is easy to shorten. In other words, under such conditions, it is easy to obtain a thick, short and difficult to break first protrusion. In addition, the film forming time of the previous step may be set to 20 minutes or more and 40 minutes or less. Under such film forming conditions, the first protrusions having an average interval of 70 nm or more and 120 nm or less at the bottom can be easily formed.

[0059] In the later stage of forming the intermediate layer, if the film forming temperature is lowered to 900-940° C. without changing the raw material gas ratio, the second protrusions are formed. The film forming time can be 30-90 minutes in total with the previous steps.

[0060] In the later stage of film formation of the intermediate layer, i.e., in the process of forming the second protrusions, if the film formation time is extended, the number of the second protrusions increases, and the width and height are likely to increase. In addition, the second protrusions extending toward the substrate are likely to be formed. Furthermore, when the film formation time is extended, the third protrusions protruding from the second protrusions are formed.

[0061] Regarding the Al2O3 layer, after the film formation of the intermediate layer, the film formation temperature can be set to 900°C to 990°C, the gas pressure can be set to 5kPa to 20kPa, and the composition of the reaction gas can be set as follows: aluminum chloride (AlCl3) gas is set to 3.5% to 15% by volume, hydrogen chloride (HCl) gas is set to 0.5% to 2.5% by volume, carbon dioxide (CO2) gas is set to 0.5% to 5.0% by volume, hydrogen sulfide (H2S) gas is set to 0% to 1.0% by volume, and the remaining component is set to hydrogen (H2) gas, thereby forming a film. The Al2O3 layer can also be composed of α-aluminum oxide.

[0062] In the above, an example in which an intermediate layer and an Al2O3 layer are sequentially formed on a substrate is described. The covering layer may also have a TiN layer, a first TiCN layer, and a second TiCN layer in order from the substrate. Furthermore, an intermediate layer and an Al2O3 layer may be sequentially formed on the second TiCN layer. In addition, a surface layer containing Ti and N may further be formed on the Al2O3 layer.

[0063] When a TiN layer is set on the surface of the substrate, the film formation temperature can be set to 800°C ~ 940°C, the gas pressure can be set to 8kPa ~ 50kPa, the composition of the reaction gas can be set to 0.5 volume % ~ 10 volume % of titanium tetrachloride (TiCl4) gas, 10 volume % ~ 60 volume % of nitrogen (N2) gas, and the remaining component is hydrogen (H2) gas, thereby forming the film.

[0064] A first TiCN layer and a second TiCN layer may also be provided on the TiN layer. The first TiCN layer may also be a so-called MT (moderate temperature)-TiCN layer. The MT-TiCN layer is formed by, for example, using raw materials including titanium tetrachloride (TiCl4) gas, nitrogen (N2) gas, and acetonitrile (CH3CN) gas, and the film forming temperature is set to 780°C to 880°C, and the film is formed at a relatively low temperature. If the thickness of the first TiCN layer is 2μm to 15μm, the first TiCN layer has high wear resistance and defect resistance. The titanium carbonitride crystals included in the first TiCN layer may also be columnar crystals that are slender in the thickness direction of the covering layer.

[0065] The second TiCN layer can also be a so-called HT (high temperature)-TiCN layer. The HT-TiCN layer can also use titanium tetrachloride (TiCl4) gas, nitrogen (N2) gas, methane (CH4) gas, etc. as raw material gas, but does not include acetonitrile (CH3CN) gas, and is formed at a film forming temperature in the range of 900°C to 1050°C. In addition, the film can also be formed at a higher temperature than the first TiCN layer. The thickness of the second TiCN layer can be 10nm to 900nm.

[0066] Here, an interface layer (not shown) containing 30 to 70 atomic % of titanium, 15 to 35 atomic % of carbon, 15 to 35 atomic % of nitrogen, and 2 to 10 atomic % of oxygen may be disposed between the first TiCN layer and the second TiCN layer. The thickness of the interface layer may be 5 nm to 50 nm.

[0067] The following is an example of the film forming conditions of the first TiCN layer. The film forming temperature can also be set to 780°C to 880°C, the gas pressure can be set to 5kPa to 25kPa, and the reaction gas composition can be set as follows in volume %: titanium tetrachloride (TiCl4) gas is set to 0.5% to 10% by volume, nitrogen (N2) gas is set to 5% to 60% by volume, acetonitrile (CH3CN) gas is set to 0.1% to 3.0% by volume, and the remaining component is hydrogen (H2) gas, thereby forming a film. At this time, by increasing the content ratio of acetonitrile (CH3CN) gas in the later stage of film formation than in the initial stage of film formation, the following structure can be set, even if the average crystal width of the titanium carbonitride columnar crystals constituting the first TiCN layer is larger on the surface side than on the substrate side.

[0068] Next, the film forming conditions of the second TiCN layer are described. The film forming temperature can also be set to 900°C to 990°C, the gas pressure can be set to 5kPa to 40kPa, and the composition of the reaction gas can be set as follows: titanium tetrachloride (TiCl4) gas is 1% to 4% by volume, nitrogen (N2) gas is 5% to 20% by volume, methane (CH4) gas is 0.1% to 10% by volume, and the remaining component is hydrogen (H2) gas, thereby forming a film.

[0069] Then, at least the cutting edge portion of the formed coating surface is ground as needed. The grinding process makes the cutting edge portion smooth, suppresses the welding of the cut material, and becomes a tool with excellent defect resistance.

[0070] As mentioned above, the covering tool of the present disclosure has been described, but the present disclosure is not limited to the above-mentioned embodiment, and various improvements and changes can be made without departing from the scope of the present disclosure.

[0071] <Cutting tools>

[0072] Next, the cutting tool of the present disclosure will be described using the drawings.

[0073] like Figure 5 As shown, the cutting tool 101 of the present disclosure is, for example, Figure 5 ) toward the second end ( Figure 5 The rod-shaped body extends from the lower end of the Figure 5 As shown, the cutting tool 101 includes a holder 105 having a pocket 103 at a first end side (front end side) and the above-mentioned cover tool 1 located in the pocket 103. Since the cutting tool 101 includes the cover tool 1, stable cutting processing can be performed for a long period of time.

[0074] The recess 103 is a portion where the covering tool 1 is mounted, and has a seating surface parallel to the lower surface of the support 105 and a restraining side surface inclined relative to the seating surface.

[0075] The covering tool 1 is positioned in the recess 103. At this time, the lower surface of the covering tool 1 may be in direct contact with the recess 103, or a sheet (not shown) may be interposed between the covering tool 1 and the recess 103.

[0076] The covering tool 1 is mounted on the bracket 105 so that at least a portion of the portion serving as the cutting edge 4 at the ridgeline where the first surface 2 and the second surface 3 intersect protrudes outward from the bracket 105. In the present embodiment, the covering tool 1 is mounted on the bracket 105 by the fixing screw 107. That is, the fixing screw 107 is inserted into the through hole 17 of the covering tool 1, and the front end of the fixing screw 107 is inserted into the threaded hole (not shown) formed in the recess 103 so that the threaded portions are screwed together, thereby mounting the covering tool 1 on the bracket 105.

[0077] Steel, cast iron, etc. can be used as the material of the bracket 105. Steel with high toughness can also be used for these members.

[0078] In this embodiment, a cutting tool 101 used for so-called turning processing is illustrated. As turning processing, for example, inner diameter processing, outer diameter processing, and grooving processing can be cited. In addition, the cutting tool 101 is not limited to a tool used for turning processing. For example, the covering tool 1 of the above embodiment can also be used in a cutting tool for rolling processing.

[0079] Example

[0080] First, add and mix in the following proportions: 6% by mass of metal cobalt powder with an average particle size of 1.2 μm, 0.5% by mass of titanium carbide powder with an average particle size of 2.0 μm, 5% by mass of niobium carbide powder with an average particle size of 2.0 μm, and the remaining portion is tungsten carbide powder with an average particle size of 1.5 μm, and form into a tool shape (CNMG120408) by stamping. Then, the binder is removed and sintered at a temperature of 1450°C to 1600°C for 1 hour in a non-oxidizing atmosphere such as an argon atmosphere and a nitrogen atmosphere to produce a matrix composed of a superhard alloy. The produced matrix is ​​brushed and the portion that becomes the cutting edge is R-honed.

[0081] Next, a covering layer is formed on the substrate of the above-mentioned superhard alloy by chemical vapor deposition (CVD). In the example of Table 1, an intermediate layer and an Al2O3 layer are directly formed on the substrate. In addition, in the example of Table 2, a TiN layer is provided on the surface of the substrate of the above-mentioned superhard alloy, and a first TiCN layer, a second TiCN layer, an intermediate layer, and an Al2O3 layer are sequentially provided on the TiN layer. The film forming conditions of the intermediate layer of each sample are respectively recorded in Tables 1 and 2. In addition, in the film forming of the intermediate layer, TiCl4 gas, N2 gas, CO gas, and H2 gas are used. The volume % of each gas is recorded in the column of the raw material gas shown in Tables 1 and 2. In Tables 1 and 2, under the film forming conditions shown in the early stage and the later stage, film forming is performed in the order of the early stage and the later stage. In addition, in the sample that only records the early stage but not the later stage, the film forming conditions are not changed and the film forming conditions are only performed by the film forming conditions of the early stage.

[0082] The film forming temperature of the Al2O3 layer is set to 950°C. The gas pressure is set to 7.5 kPa. The composition of the reaction gas is as follows: aluminum chloride (AlCl3) gas is set to 3.7 volume %, hydrogen chloride (HCl) gas is set to 0.7 volume %, carbon dioxide (CO2) gas is set to 4.3 volume %, hydrogen sulfide (H2S) gas is set to 0.3 volume %, and the remaining component is hydrogen (H2) gas. The film forming time of the Al2O3 layer is set to 380 minutes.

[0083] The film forming conditions of the TiN layer in the example of Table 2 are as follows. The film forming temperature of the TiN layer is set to 850 degrees. The gas pressure is set to 16 kPa. The composition of the reaction gas is as follows: 1.0 volume % of titanium tetrachloride (TiCl4) gas, 38 volume % of nitrogen (N2) gas, and the remaining component is hydrogen (H2) gas. The film forming time is set to 180 minutes.

[0084] The film forming conditions of the first TiCN layer in the example of Table 2 are as follows. The film forming temperature is set to 850°C and the gas pressure is set to 9.0 kPa. The reaction gas composition is set as follows in volume %: titanium tetrachloride (TiCl4) gas is set to 4.0 volume %, nitrogen (N2) gas is set to 23 volume %, acetonitrile (CH3CN) gas is set to 0.4 volume %, and the remaining component is hydrogen (H2) gas. The film forming time is set to 400 minutes.

[0085] The film forming conditions of the second TiCN layer in Table 2 are as follows. The film forming temperature is set to 950°C. The gas pressure is set to 13 kPa. The composition of the reaction gas is set as follows: titanium tetrachloride (TiCl4) gas is set to 4 volume%, nitrogen (N2) gas is set to 20 volume%, methane (CH4) gas is set to 8 volume%, and the remaining component is hydrogen (H2) gas. The film forming time is set to 80 minutes.

[0086] The samples in Tables 1 and 2 were observed by SEM in a cross section including the covering layer, and the proportion of the composite protrusions in the plurality of first protrusions was measured. In addition, the morphology of the first protrusions and the composite protrusions was observed. The results are shown in Tables 1 and 2.

[0087] The obtained samples were used to perform intermittent cutting tests under the following conditions to evaluate the defect resistance. The test results are shown in Tables 1 and 2. The number of impacts (ratios) shown in Tables 1 and 2 are the ratios of the number of impacts of each sample to the number of impacts of Sample No. 1. The larger the number of impacts (ratio), the better the defect resistance.

[0088] <Interrupted cutting conditions>

[0089] Workpiece: Chrome-molybdenum steel with 4 embedded grooves (SCM440)

[0090] Tool shape: CNMG120408

[0091] Cutting speed: 300m / min

[0092] Feed speed: 0.3mm / rev

[0093] Incision: 1.5mm

[0094] Others: Use water-soluble cutting fluid

[0095] Evaluation item: Determine the number of impacts that cause the Al2O3 layer to peel off.

[0096] [Table 1]

[0097]

[0098] [Table 2]

[0099]

[0100] In Table 1, the ratio of the composite protrusions among the plurality of first protrusions is 30% or less, and the covered tools of Samples No. 3, 5 to 9 as the embodiments of the present disclosure all have excellent defect resistance. The defect resistance of Samples No. 1 and 2, in which the ratio of the composite protrusions among the plurality of first protrusions exceeds 30%, is inferior to that of Samples No. 3, 5 to 9. In addition, the defect resistance of Samples No. 4 and 10 without composite protrusions is inferior to that of Samples No. 3, 5 to 9.

[0101] In Table 2, the ratio of the composite protrusions among the plurality of first protrusions is 30% or less, and the covered tools of Samples No. 13, 15 to 19 as the embodiments of the present disclosure are all excellent in defect resistance. The defect resistance of Samples No. 11 and 12, in which the ratio of the composite protrusions among the plurality of first protrusions exceeds 30%, is inferior to that of Samples No. 13, 15 to 19. In addition, the defect resistance of Samples No. 14 and 20, which do not have composite protrusions, is inferior to that of Samples No. 13, 15 to 19.

[0102] -Explanation of symbols-

[0103] 1 Covering tools

[0104] 2 First surface, rake face

[0105] 3 Second side, back face

[0106] 4 Cutting edges

[0107] 5 Matrix

[0108] 7 Covering

[0109] 9 Middle Layer

[0110] 10a TiN layer

[0111] 10b First TiCN layer

[0112] 10c TiCN layer

[0113] 11 Al2O3 layer

[0114] 13. First protrusion

[0115] 13a Bottom of the first protrusion

[0116] 13b Front end of the first protrusion

[0117] 15 Second protrusion

[0118] 15a Bottom of the second protrusion

[0119] 15b Front end of the second protrusion

[0120] 17 Compound protrusion

[0121] 19 The third protrusion

[0122] 101 Cutting Tools

[0123] 103 recess

[0124] 105 Bracket

[0125] 107 Fixing screw.

Claims

1. A coating tool comprising a substrate and a coating layer located on a surface of the substrate, The cover layer comprises an Al2O3 layer and an intermediate layer containing Ti, The Al2O3 layer is arranged in contact with the intermediate layer at a position farther from the substrate than the intermediate layer. The intermediate layer has a plurality of first protrusions protruding toward the Al2O3 layer, At least one of the plurality of first protrusions is a composite protrusion having a second protrusion protruding in a direction intersecting with a protruding direction of the first protrusion, The ratio of the composite protrusions in the plurality of first protrusions is less than 20%, The ratio of the average height of the second protrusions to the average width of the bottoms of the second protrusions is greater than the ratio of the average height of the plurality of first protrusions to the average width of the bottoms of the plurality of first protrusions. The angle of the front ends of the plurality of first protrusions is greater than or equal to 50° and less than or equal to 90°.

2. The covering tool according to claim 1, wherein: The average number of the second protrusions included in the composite protrusion is 1.2 or less.

3. The covering tool according to claim 1 or 2, wherein: A ratio of an average height of the plurality of first protrusions to an average width of bottoms of the plurality of first protrusions is 1.2 or less.

4. The covering tool according to claim 1 or 2, wherein: An average width of the bottoms of the plurality of first protrusions is greater than or equal to 10 nm and less than 50 nm, and an average height of the first protrusions is greater than or equal to 10 nm and less than 60 nm.

5. The covering tool according to claim 1 or 2, wherein: The composite protrusion has a third protrusion protruding in a direction intersecting with a protruding direction of the second protrusion.

6. The covering tool according to claim 1 or 2, wherein: The covering layer includes a first TiCN layer, a second TiCN layer, the intermediate layer, and the Al 2 O 3 layer in order from the substrate.

7. The covering tool according to claim 1 or 2, wherein: The intermediate layer contains C and N.

8. The covering tool according to claim 7, wherein: The intermediate layer also contains O.

9. A cutting tool comprising: a bracket extending from the first end toward the second end and having a recess at a front end side of the first end; and The covering tool according to any one of claims 1 to 8 is located in the recess.

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