Coated cutting tools

Abstract

The present invention relates to a coated cutting tool (1) comprising a cemented carbide base material (5) and a coating (6), wherein the cemented carbide comprises WC particles, eta phase particles, and a metal binder, the metal binder comprises Co and Cr, the Co content in the cemented carbide is 6-14% by weight, the eta phase content in the cemented carbide is 1-10% by volume, the average particle size of the eta phase particles is 0.5-5 μm, the Cr / Co weight ratio in the cemented carbide is 0.005-0.025, and the coating (6) is Ti 1-x Al x The first nanolayer (9) is N(0.35≦x≦0.70), and Ti 1-y Si y A coated cutting tool comprising a nanomultilayer structure (8) in which a second nanolayer (10) having N(0.12≦y≦0.25) is alternately stacked.

Description

【Technical Field】 【0001】 The present invention relates to a coated cutting tool having a nano-multilayer structure of (Ti, Si)N and (Ti, Al)N. The coating is deposited on a cemented carbide substrate containing eta-phase particles distributed in a binder containing cobalt and chromium. 【Background Art】 【0002】 Introduction Metal working operations include turning, milling, and drilling. 【0003】 In order to achieve a long tool life, a coated cutting tool such as an insert needs to have high resistance to various types of wear, such as flank wear resistance, crater wear resistance, chipping resistance, and peeling resistance. 【0004】 Various metal working operations have various effects on coated cutting tools. For example, turning is a continuous metal working operation, while milling is essentially intermittent. In milling, the thermal load and mechanical load change over time. The thermal load generates thermal stress, which may cause so-called thermal cracks (referred to here as "comb-like cracks"). The mechanical load causes fatigue at the cutting edge, and chipping, that is, a phenomenon in which small pieces of the cutting edge are peeled off from the remaining part of the substrate, may occur. Therefore, the common types of wear of a coated cutting tool in milling are cracks and chipping. In particular, if the toughness of the coating at the cutting edge is high, such chipping may be reduced. Therefore, in order to extend the tool life, it is very important to increase the comb-like crack resistance and the toughness of the cutting edge line. 【0005】 Heat-resistant superalloys (HRSA) and titanium, i.e., ISO-S materials, are important materials, for example, in the aerospace industry. Machining ISO-S materials is difficult due to the characteristics of the workpiece material. Since these materials are hard and prone to fouling, special requirements are imposed on cutting tools. For example, since ISO-S materials have low thermal conductivity, high temperatures are generated during machining, resulting in wear. 【0006】 There is a continuous demand for cutting tools coated with a coating having excellent wear resistance. 【0007】 An object of the present invention is to provide a coated cutting tool that exhibits at least high chipping resistance and high toughness, particularly in ISO-S milling applications. 【0008】 This invention The present invention provides a combination of a cemented carbide substrate containing WC and an eta phase uniformly distributed in a metal binder containing Co and Cr, and a coating further deposited on this substrate, the coating containing a nano multilayer coating in which (Ti, Si)N layers and (Ti, Al)N layers alternate. 【0009】 The coated cutting tool according to the present invention exhibits surprisingly high toughness behavior in the machining of titanium. 【0010】 A coated cutting tool comprising a cemented carbide substrate and a coating, - The cemented carbide contains WC particles, eta phase particles, and a metal binder, the metal binder contains Co and Cr, the Co content in the cemented carbide is 6 to 14% by weight, the eta phase content in the cemented carbide is 1 to 10% by volume, the average particle size of the eta phase particles is 0.5 to 5 μm, the Cr / Co weight ratio in the cemented carbide is 0.005 to 0.025, and the coating is Ti 1-x Al x N (0.35 ≦ x ≦ 0.70) as a first nano layer, and Ti 1-y Si yThe present invention relates to a coated cutting tool comprising a nanomultilayer structure in which a second nanolayer (10) of N(0.12≦y≦0.25) is alternately stacked, the sequence of one first nanolayer and one second nanolayer forming a layer period, and the average layer period thickness of the nanomultilayer is ≦10 nm. 【0011】 The cemented carbide of the present invention comprises WC particles and eta phase particles embedded in a metal binder. The metal binder is composed of Co and Cr, and also contains W, which is dissolved into the metal binder from the WC particles during the sintering of the cemented carbide. 【0012】 The Co content in the cemented carbide of the present invention is appropriately 7 to 13% by weight, and preferably 8 to 12% by weight. 【0013】 In the cemented carbide of the present invention, it is preferable to have a Cr / Co weight ratio of 0.010 to 0.020. 【0014】 The cemented carbide alloys having the Cr / Co weight ratio range of the present invention exhibit high solid solution strengthening. The work hardening properties of Co are improved, high-temperature hardness properties are enhanced, and chemical resistance, i.e., corrosion resistance, is also improved. When Cr is added to cemented carbide, some Cr is included in the eta phase particles. Some Cr also remains as a solid solution in the metal binder phase containing Co. Cr also functions as a grain growth inhibitor during sintering, limiting the continuous growth and coarsening of WC grains. If the Cr content is too low, Cr still affects the growth of WC grain size, but the above-mentioned solid solution effect is limited. If the Cr content is too high, the cemented carbide becomes too hard and brittle, making it unsuitable for ISO-S milling applications. 【0015】 The eta phase content in the cemented carbide of the present invention is 1 to 8 volume%, preferably 2 to 8 volume%, and more preferably 3 to 6 volume%. If the eta phase content is too high, most of the Co content in the metal binder is consumed by the eta phase particles, making the cemented carbide very brittle. If the eta phase content is too low, the eta phase particles form clusters, increasing the risk of brittleness due to improper distribution of the eta particles. The amount of eta phase in the cemented carbide can be determined by LOM (optical microscope) image analysis. The area fraction in the image is thought to correspond to the volume fraction in the cemented carbide. 【0016】 The cemented carbide according to the present invention has a low carbon content, so eta phase particles are formed. In this disclosure, the eta phase is Me 12 This refers to a carbide selected from C and Me6C, where Me is one or more metals selected from W and binder phase metals, and therefore the carbide is, for example, (W, Co, Cr)6C and / or (W, Co, Cr) 12 It can be C. 【0017】 In the present invention, the cemented carbide contains finely distributed eta phase particles. The average particle size of the eta phase particles in the cemented carbide of the present invention is 0.5 to 5 μm, preferably 1 to 4 μm. In this disclosure, the average particle size of the eta phase particles is defined as the average value of the maximum Ferret diameter of the eta phase particles. This value can be determined, for example, by image analysis of optical microscope (LOM) images. 【0018】 Eta phase particles are appropriately and uniformly distributed within the cemented carbide. 【0019】 Since the distributed eta phase particles of the present invention are formed during the sintering process, carbon depletion and equilibrium temperature must be controlled during the process to achieve the desired eta phase particle size and content. Eta phase particles usually exist in an undesirable form as very large particles, which can form aggregates of smaller particles, leading to brittle cemented carbides. Such undesirable forms of eta phase particles typically have particle sizes greater than 50 μm, or even greater than 100 μm. 【0020】 The difference in substoichiometric carbon content between achieving undesirable large or aggregated eta phase particles and achieving distributed eta phase particles with the target small particle size can be very small. To approach this limit, it is necessary to monitor the formation of microstructure and prevent the generation of unwanted large particles or aggregates. Carefully adjusting the carbon content and then monitoring the results in terms of the resulting microstructure is a well-known procedure to those skilled in the art. 【0021】 In one embodiment, the average WC grain size in the cemented carbide is 0.6 to 1.2 μm, preferably 0.7 to 1.0 μm. 【0022】 In one embodiment of the present invention, the cemented carbide contains 70 to 90 volume percent of WC, preferably 75 to 85 volume percent of WC. The amount of WC in the cemented carbide can be determined by image analysis using an optical microscope (LOM). The area fraction in the image is considered to correspond to the volume fraction in the cemented carbide. 【0023】 In one embodiment of the present invention, the content of the eta phase in a portion of the substrate adjacent to the surface of the substrate corresponds to the content in the innermost part of the substrate. In one embodiment of the present invention, the eta phase distribution is constant throughout the cemented carbide substrate; that is, the cemented carbide does not have an eta phase gradient or an eta phase-free zone, as described in, for example, U.S. Patent No. 4,843,039. It is preferable that the eta phase distribution is as uniform as possible. 【0024】 In one embodiment of the present invention, the cemented carbide contains 8 to 28 volume percent of a metal binder, preferably 13 to 23 volume percent of a metal binder. 【0025】 In one embodiment, the cemented carbide comprises a metal binder, an eta phase, and the remainder WC. 【0026】 The metal binder contains Co and Cr. Additionally, some amount of W is dissolved in the metal binder. While W inevitably dissolves into the metal binder during sintering, the exact amount depends on several factors, including the overall composition of the cemented carbide and its precise carbon content. 【0027】 The cemented carbide of the present invention has a quasi-stoichiometric carbon content (SCC) within a certain range. Quasi-stoichiometric carbon content is a measure of the carbon content relative to the stoichiometric value of carbon. 【0028】 The stoichiometric carbon content can be calculated by assuming that WC is perfectly stoichiometric, i.e., the atomic ratio W:C is 1:1. Since other carbide-forming elements also exist, it is assumed that these carbides are also stoichiometric. 【0029】 In this disclosure, the term "quasi-stoichiometric carbon content (SCC)" is obtained by subtracting the stoichiometric carbon content (weight%) calculated based on other carbides that may be present in WC and cemented carbide from the total carbon content (weight%) determined from chemical analysis. 【0030】 For example, if a particular cemented carbide has a stoichiometric carbon content of 5.60 wt%, the same cemented carbide could be manufactured with a carbon content of 5.30 wt%, resulting in a quasi-stoichiometric carbon content of -0.30 wt%. 【0031】 To achieve an appropriate carbon content in the final production of the sintered cemented carbide, W and / or W2C are added to the sintered cemented carbide in such amounts that the quasi-stoichiometric carbon content (SCC) is -0.40 wt% ≤ SCC ≤ -0.16 wt% or -0.35 wt% ≤ SCC ≤ -0.17 wt%. 【0032】 Because cemented carbide has a very low carbon content, an eta phase is formed. However, the formed eta phase does not exist as large particles or aggregates, but rather is well distributed with fine particle sizes. By carefully controlling the carbon balance during manufacturing, the desired form of the eta phase can be provided. 【0033】 If the carbon content of a sintered cemented carbide is too low, i.e., below the quasi-stoichiometric carbon content of -0.40 wt%, the amount of eta phase becomes too large, significantly increasing the particle size and making the cemented carbide brittle. On the other hand, if the carbon content is higher than the quasi-stoichiometric carbon content of -0.16 wt% but still within the eta phase formation region, the formed eta phase is unevenly distributed in the form of large aggregates, leading to a decrease in the toughness of the cemented carbide. 【0034】 The cemented carbide of the present invention can be manufactured according to the following steps. - Process of supplying raw materials - Process of providing the pulverized liquid - A process for manufacturing cemented carbide by crushing powder, drying it, pressurizing it, and sintering it. 【0035】 Normally, some carbon is lost during sintering due to the presence of oxygen. Since oxygen reacts with carbon during sintering to release CO or CO2, altering the carbon balance, the amount of one or more W and W2C added must be adjusted. The exact amount of carbon lost during sintering depends on the raw materials and manufacturing techniques used; therefore, adjusting the amount of W and / or W2C added to achieve the desired eta phase characteristics in the sintered material is a matter for those skilled in the art. 【0036】 The quasi-stoichiometric carbon content in sintered materials differs somewhat from that in powders. This is because during sintering, some of the carbon reacts with oxygen, releasing gas as CO or CO2, which reduces the final total carbon content of the cemented carbide. Typically, the quasi-stoichiometric carbon content in sintered materials is about 5-25% lower than that in powder compositions. For example, if the quasi-stoichiometric carbon content in a powder composition is -0.20 wt%, the quasi-stoichiometric carbon content in sintered material will be approximately -0.21 wt% to approximately -0.25 wt%. 【0037】 The stoichiometric carbon content of cemented carbide can be determined by first measuring the total carbon content in the sample, for example, using a LECO CS844 instrument. The cobalt content is also measured, for example, by X-ray fluorescence analysis. Subtracting the amounts of cobalt and carbon from the total weight of the sample gives the tungsten content, which is used to calculate the stoichiometric carbon content, assuming a WC ratio of 1:1. 【0038】 The particle size of the WC powder used is selected to obtain the desired WC particle size in the final cemented carbide, taking into account the influence of all components in the raw material powder mixture and the grinding procedure used. The particle size (FSSS) of the WC powder is appropriately between 2 μm and 7 μm. 【0039】 The powder forming the binder phase is Co, which is added in desired amounts. Furthermore, Cr is added in desired amounts, preferably in the form of Cr3C2, and in the final cemented carbide, some of it is included in the eta phase and some is dissolved into the binder phase. 【0040】 The slurry, containing the powder that forms the hard component and the powder that forms the binder phase, is properly mixed by a grinding operation in either a ball mill or an attritor mill. Any liquid commonly used as a grinding fluid in conventional cemented carbide manufacturing can be used. The slurry containing the powder material is then dried to properly form aggregated granules. 【0041】 Subsequently, a green body is formed from the dried powder / granules by pressing operations such as a uniaxial press or multiaxial press. 【0042】 The green bodies formed from the manufactured powder / granules are then sintered according to conventional sintering methods such as vacuum sintering, sintering HIP, discharge plasma sintering, and gas pressure sintering (GPS). 【0043】 The sintering temperature is typically between 1300°C and 1580°C, or between 1360°C and 1450°C. 【0044】 The coating is such that the first nano-layer is Ti 1-x Al x N (0.35 ≦ x ≦ 0.70), and the second nano-layer is Ti 1-y Si y N (0.12 ≦ y ≦ 0.25), and is composed of an alternating layer nano-multilayer. 【0045】 For the first nano-layer Ti 1-x Al x N, preferably 0.45 ≦ x ≦ 0.70, more preferably 0.55 ≦ x ≦ 0.65. 【0046】 For the second nano-layer Ti 1-y Si y N, preferably 0.14 ≦ y ≦ 0.23, more preferably 0.17 ≦ y ≦ 0.21. 【0047】 The average layer period thickness of the nano-multilayer is suitably 2 - 7 nm, preferably 3 - 6 nm. 【0048】 In one embodiment, the nano-multilayer has a columnar structure with an average column width of ≦ 100 nm, or ≦ 70 nm. In one embodiment, the average column width of the nano-multilayer film is 5 - 100 nm, or 10 - 70 nm, or 25 - 70 nm. 【0049】 The thickness of the nano-multilayer is preferably about 0.5 - about 10 μm, preferably about 0.5 - about 5 μm, more preferably about 1 - about 3 μm. 【0050】 The nano-multilayer film is suitably a layer deposited by cathodic arc evaporation. 【0051】 In one embodiment, the coating includes a layer of TiN, (Ti, Al)N, or (Cr, Al)N between the substrate and the nano-multilayer, preferably located as the innermost layer of the coating. Preferably, this layer is (Ti, Al)N. When using (Ti, Al)N, (Ti, Al)N is Ti 1-z Al zA suitable N(0.35≦z≦0.70, preferably 0.45≦z≦0.70, most preferably 0.50≦z≦0.65) is used. In a preferred embodiment, the Ti-Al relationship in (Ti,Al)N is the same as the Ti-Al relationship in the first nanolayer of the nanomultilayer. The thickness of this layer is about 0.1 to about 2 μm, preferably about 0.5 to about 1.5 μm. 【0052】 In one embodiment, the coating includes an uppermost layer of (Ti,Si)N. The (Ti,Si)N is Ti 1-v Si v It is preferable that N is (0.12 ≤ v ≤ 0.25, or 0.14 ≤ v ≤ 0.23, or 0.17 ≤ v ≤ 0.21). In a preferred embodiment, the Ti-Si relationship in the top layer of (Ti, Si)N is the same as the Ti-Si relationship in the second nanolayer of the nanomultilayer. The thickness of this top layer can be about 0.02 to about 0.5 μm, preferably about 0.05 to about 0.2 μm. 【0053】 In a preferred embodiment, the coating is Ti 1-x Al x A first nanolayer with N(0.55≦x≦0.65) and Ti 1-y Si y The nanomultilayer film contains alternating layers of a second nanolayer of type N (0.17 ≤ y ≤ 0.21), with an average layer periodic thickness of 3-6 nm, an average column width of 25-70 nm, and a nanomultilayer film thickness of approximately 1-3 μm. Beneath the nanomultilayer film closest to the substrate, there is an innermost layer of (Ti,Al)N with a thickness of approximately 0.5-1.5 μm. 【0054】 Coated cutting tools are suitable as cutting tool inserts, drills, or solid end mills for metalworking. Preferably, the cutting tool inserts are milling inserts or solid end mills. [Brief explanation of the drawing] 【0055】 [Figure 1] A schematic diagram of one embodiment of a cutting tool, which is a milling insert, is shown. [Figure 2] This figure shows a schematic cross-sectional view of an embodiment of a coated cutting tool of the present invention, illustrating a coating that includes a layer different from the substrate. [Figure 3] This shows an LOM (optical microscope) image of a cross-section of an embodiment of the substrate used in the present invention. [Figure 4] Figure 3 shows a magnified view of the lower right corner of the LOM image. 【0056】 Detailed description of the embodiments in the drawings Figure 1 shows a schematic diagram of one embodiment of a cutting tool (1) having a rake face (2), a flank face (3), and a cutting edge (4). In this embodiment, the cutting tool (1) is a milling insert. Figure 2 is a schematic cross-sectional view showing one embodiment of a coated cutting tool of the present invention, having a base body (5) and a coating (6). The coating (6) has an inner (Ti,Al)N layer (7) and a subsequent Ti 1-x Al x N(9) nanolayer and Ti 1-y Si y It is composed of a nanolayer (8) in which nanolayers of N(10) are alternately stacked. Figure 3 shows an LOM (optical microscope) of a cross-section of an embodiment of the cemented carbide substrate used in the present invention. The cemented carbide is composed of eta phase particles (dark), WC particles (gray), and a metal binder (light grayish-white). Figure 4 shows a magnified view of the lower right corner of the LOM image of Figure 3. The cemented carbide contains eta phase particles (11), WC particles (12), and a metal binder (13). 【0057】 Definition and Method The amount of eta phase in cemented carbide was determined by LOM (optical microscope) image analysis using the "Analyze particles" function and "include holes" and "0-Infinity" filter settings of ImageJ software. Before measurement, color LOM images were converted to 8-bit grayscale images using automatic thresholding. The image magnifications were 1000x and 2000x, with two measurements taken at each magnification; the values ​​in Table 2 are the average of these. Therefore, the values ​​in the table are the average of a total of four image analyses (two measurements per image) performed on the two images. The area fraction in the image is thought to correspond to the volume fraction in the cemented carbide. The volume fraction of WC can be determined in the same way as the volume fraction of the eta phase. 【0058】 In this disclosure, the average particle size of the eta phase particles is defined as the average value of the maximum ferret diameter of the eta phase particles. This value was determined by image analysis of optical microscope (LOM) images using the "Analyze particles" function and the "include holes" and "0-Infinity" filter settings of the Image J software. The "exclude on edges" ferret size option was additionally enabled in the "Analyze particles" function. Before measurement, color LOM images were converted to 8-bit grayscale images using automatic thresholding. The images used for analysis were LOM images at 1000x magnification, and 10 images were processed to obtain the maximum ferret diameter of each image, and the overall average of the maximum ferret diameters was calculated. 【0059】 The stoichiometric carbon content in sintered cemented carbide can first be calculated by measuring the total carbon content in the sintered cemented carbide. Appropriate instruments such as the LECO CS 844 instrument are used. The sample was pulverized before analysis. W, Co, and Cr content are measured by XRF (X-ray fluorescence) using, for example, the Panalytical Axios Max Advanced instrument. The W content is obtained by subtracting the amounts of cobalt, chromium, and carbon from the total weight of the sample, and this is used to calculate the stoichiometric carbon content, assuming a WC ratio of 1:1. Subtracting the stoichiometric carbon content from the already measured total carbon content yields the quasi-stoichiometric carbon value. 【0060】 In this specification, the particle size (d) of WC is determined from the value of its magnetic coercivity. The relationship between the coercivity and particle size of WC is described, for example, in Roebuck et al., Measurement Good Practice No. 20, National Physical Laboratory, ISSN 1368-6550, November 1999, Revised February 2009, Section 3.4.3, pages 19-20. For the purposes of this application, the particle size (d) of WC is determined according to formula (8) on page 20 of the above-mentioned document. K=(c1+d1W Co )+(c2+d2W Co ) / d Rearranging them results in the following: d=(c²+d²W) Co ) / (K-(c1+d1W Co )), in the formula d = WC grain size of the cemented carbide body, K = coercivity of the cemented carbide body (kA / m), measured according to DIN IEC 60404-7 standard, W Co =The weight %Co in the cemented carbide body is c1=1.44, c2=12.47, d1=0.04, and d2=-0.37. 【0061】 The coating thickness was measured in the polished cross-section of the SEM image. 【0062】 The term "average layer period thickness" refers to the average thickness of combination AB in a nanomultilayer coating consisting of a first nanolayer A and a second nanolayer B in a nanomultilayer ABABA… structure. If the deposition process is known, it can be calculated by dividing the total thickness of the nanomultilayer by the number of AB deposition cycles (equivalent to the number of rotations when the substrate is rotated during deposition). 【0063】 Alternatively, the calculation can be performed by using TEM analysis of the cross-section of the nanomultilayer film to count the number of combinations of continuous AB nanolayers over a length of at least 250 nm and calculating the average value. 【0064】 In nanomultilayer films, the term "average column width" refers to the average value of the crystalline columns, or "grains," in the nanomultilayer film. A length of at least 500 nm perpendicular to the growth direction of the layer is considered, and the column width is measured over this length at at least four different locations within the nanomultilayer at a distance of 500 nm from the bottom interface of the nanomultilayer. 【0065】 When the total thickness of the nanomultilayer film is only 0.5 μm, the measurement site is located just below the outer surface of the nanomultilayer film. Suitable analytical methods include transmission electron microscopy (TEM). 【0066】 Examples Example 1: Coated cutting tools were manufactured using sintered cemented carbide cutting tool insert blanks with shape R390-11. 【0067】 The composition of the first cemented carbide was 10.40 wt% Co, 0.15 wt% Cr, and the remainder being WC - Base Material 1 (part of the present invention). The composition of the reference cemented carbide was 11.2 wt% Co, 1.12 wt% Cr, and the remainder being WC - Base Material 2 (reference). 【0068】 The cemented carbide was prepared from raw material powders according to Table 1. TIFF2026519046000002.tif44170 【0069】 The powder was ground in a ball mill with a grinding solution (water / ethanol in a 9 / 91 ratio) and an organic binder (2% by weight of PEG). The dry powder weights shown in Table 1 do not include the amount of PEG. After grinding, the slurry was dried. The dried aggregate was then compressed into a green body. The green body was sintered at 1410°C in an Ar and CO atmosphere of 40 mbar. 【0070】 The chemical composition of sintered cemented carbide is measured using XRF (X-ray fluorescence) with a Panalytical Axios Max Advanced instrument. 【0071】 The carbon content in the powder was adjusted to achieve the desired microstructure in the sintered cemented carbide. 【0072】 Table 2 shows the Co and Cr content in the sintered cemented carbide substrate. The coercivity values ​​and calculated average WC grain size are also shown. TIFF2026519046000003.tif52170 【0073】 The eta phase content and the average particle size of eta phase particles were measured according to the methods disclosed herein. The results are shown in Table 3. Eta phase particles in the eta phase-containing samples were uniformly distributed throughout the substrate, and no gradient of eta phase content was observed within the samples. The cemented carbide did not contain gamma phase particles, very large eta phase particles, or graphite. TIFF2026519046000004.tif47170 【0074】 The cemented carbide blank was coated by cathode arc deposition in a vacuum chamber equipped with an arc flange. 【0075】 The target is Ti 0.80 Si 0.20 They were attached to the two flanges on opposite sides of each other. The target is Ti 0.40 Al 0.60The two flanges were mounted on opposite sides of each other. The Ti target was mounted on one flange. The targets were circular and planar with a diameter of 100 mm, which were available on the market. A suitable arc source for use was the Super Fine Cathode (SFC) from Kobelco (Kobe Steel Ltd). 【0076】 Uncoated blanks of both substrate 1 and substrate 2 were mounted on a pin that rotated three times within the PVD chamber. 【0077】 The chamber is in a high vacuum (10 -2 The chamber was evacuated to less than Pa and heated to 550-650°C by a heater inside the chamber. The blank was then etched with Ar plasma for 60 minutes. 【0078】 Next, to improve the adhesion between the coating and the substrate, the substrate was etched with Ti ions. This process was carried out for 4 minutes with a DC bias voltage of -200V, an arc current of 150A applied to the Ti target, and an Ar pressure of 0.7Pa. 【0079】 Next, first, a Ti with a thickness of approximately 0.8 μm 0.40 Al 0.60 The innermost layer of N was deposited. The chamber pressure (reaction pressure) was set to 4 Pa ​​with N2 gas, and a DC bias voltage of -30 V (relative to the chamber wall) was applied to the blank assembly. The cathode of the Ti-Al target was operated in arc discharge mode with a current of 150 A (each) for 40 minutes. 【0080】 Next, the nanolayers of (Ti,Si)N and (Ti,Al)N are Ti 0.40 Al 0.60 It was deposited on top of the innermost layer of N. 【0081】 The chamber pressure (reaction pressure) was set to 4 Pa ​​with N2 gas, and a DC bias voltage of -40 V (relative to the chamber wall) was applied to the blank assembly. The cathodes of the Ti-Al and Ti-Si targets were operated in arc discharge mode with an arc current of 150 A (each) for 30 minutes (four flanges). A nanolayer coating with a thickness of approximately 1.3 μm was deposited on the blank. Due to the target setting, two nanolayer periods were formed with each rotation of the substrate table. The table rotation speed was adjusted so that the average thickness of the nanolayer period was approximately 4 nm. 【0082】 Finally, Ti with a thickness of approximately 0.1 μm 0.80 Al 0.20 The top layer of N was deposited. The chamber pressure (reaction pressure) was set to 4 Pa ​​with N2 gas, and a DC bias voltage of -70 V (relative to the chamber wall) was applied to the blank assembly. The cathodes of the Ti-Al and Ti-Si targets were operated in arc discharge mode with an arc current of 150 A (each) for 5 minutes (two flanges). 【0083】 Ti 0.40 Al 0.60 N / Ti 0.80 Si 0.20 An insert of substrate 1 having an N-nanometer multilayer coating is referred to as "Sample 1 (Invention)". 【0084】 Ti 0.40 Al 0.60 N / Ti 0.80 Si 0.20 The insert of substrate 2 having an N-nanometer multilayer coating is referred to as "Sample 2 (reference)". 【0085】 As a further reference sample to be included in the performance test, Ti was used in a different deposition run. 0.33 Al 0.67 Coated cutting tools were fabricated by depositing a (Ti,Al)N layer of approximately 2 μm using the target composition. 【0086】 The (Ti,Al)N layer was deposited on a sintered cemented carbide cutting tool insert blank of type substrate 2 (reference), shape R390-11T308M-PM. Using this reference TiAlN layer allowed for correction of any differences between performance test runs, enabling comparison of results from different test runs. The cemented carbide blank was coated by cathode arc evaporation in a PVD vacuum chamber equipped with multiple arc flanges (each flange containing multiple cathode evaporators). 【0087】 Ti 0.33 Al 0.67 The target was mounted on the evaporator. Target technology packages suitable for arc evaporation are available from market suppliers such as IHI Hauzer Techno Coating BV, Kobelco (Kobe Steel, Ltd.), and Oerlikon Balzers. 【0088】 The PVD chamber consists of a circular substrate table, to which an uncoated cutting tool insert blank is attached on a pin. The insert is mounted so that its side faces directly towards the target during rotation. 【0089】 The chamber pressure (reaction pressure) was set to 1 Pa with N2 gas, and a DC bias voltage of -100V (relative to the chamber wall) was applied to the blank assembly. The cathode was operated in arc discharge mode with a current of 140A (each). Reference coating: Ti 0.33 Al 0.67 An insert of substrate 2 (reference) containing N is denoted as "sample 3 (reference)". 【0090】 To confirm the actual elemental composition of the nanomultilayer films, the average composition was analyzed for several samples using energy-dispersive X-ray spectroscopy (EDS). EDS measurements were performed over distances containing numerous nanolayers using SEM on cross-sections of the coatings. 【0091】 As a result, the deviation from the theoretical composition was confirmed to be only on the order of 1-2 percent. This is within the accuracy range of the EDS method. Therefore, it can be concluded that the actual elemental compositions of Ti, Al, and Si in the nanomultilayer film layers are in close agreement with the respective target compositions used. Furthermore, for the innermost TiAlN layer and the top TiSiN layer, the respective target compositions are considered to correspond to the compositions of the deposited layers. 【0092】 Example 2: A cutting test was performed to determine the performance of the prepared sample. 【0093】 Explanation of terms used: The following expressions / terms are commonly used in metal cutting, but will be explained. Vc(m / min): Cutting speed (meters / minute) fz (mm / tooth): Feeding speed in millimeters per tooth a e (mm): Radial cutting depth in millimeters a p (mm): Axial cutting depth in millimeters z: (number) Number of cutter teeth 【0094】 Titanium toughness test: This test evaluates resistance to major breakage. This is an entry test, performed by up-milling, with the cutter positioned at 0° exit, i.e., at half the cutter diameter engagement (ae). Under these conditions, the chip thickness ejected from the workpiece material is maximized. These conditions require an operation demanding high toughness. The test is performed in the y-direction of the specimen, and the number of entries until the cutoff criterion is reached is recorded. Wear of the variant is continuously measured during the test. To obtain the same conditions during the test, the surface is cleaned using a "cleaning cutter" when the number of entries in each row is reached. A "cleaning cutter" is also used at the first entry in each row (right x-direction) because the conditions are different at this entry. 【0095】 Workpiece material: Ti6Al4V Filling amount: 04696 MC S4.2.Z.AN Dim: 600 x 200 x 50 mm Hardness: 330 HB Cutter: R390-32mm (R390-032A32-11M) Tool length: 132mm Coolant: Internal 10 bar Vc=35m / min fz = 0.20 mm a e = 16mm Inlet depth = 27mm a p = 2.0 mm z=1 Insert type R390-11T308M-MM Cutoff criteria: Breakage / chipping measured on the rake face or flank face, ≥1.0mm. 【0096】 Tool life is reported as the number of entry points required to achieve the cutoff criterion. 【0097】 Uncoated cutting tool blanks with base material 1 and 2, with a shape R390-11 (see Example 1), were tested using the "Titanium Toughness Test". The results are shown in Table 4. TIFF2026519046000005.tif37170 【0098】 Therefore, substrate 1 showed approximately four times longer tool life in toughness tests. 【0099】 Furthermore, the coated cutting tool of Example 1 was tested in a "toughness test in titanium." Since two different test runs were performed, reference samples (Sample 2 and Sample 4) were tested along with Sample 1 (Invention) and Sample 3 (Comparison), respectively, allowing for a comparison of the performance of Sample 1 and Sample 3. 【0100】 The results are shown in Table 6. TIFF2026519046000006.tif32170 【0101】 Therefore, the base material 1 and Ti 0.40 Al 0.60 N / Ti 0.80 Si 0.20 Sample 1, which combines an N nano multilayer coating, is shown in Reference Material 3 (Substrate 2 + Reference Coating Ti). 0.33 Al 0.67 It showed approximately 7 times longer tool life in toughness tests compared to N. 【0102】 Comparative sample 2 consists of substrate 2 and Ti 0.40 Al 0.60 N / Ti 0.80 Si 0.20 This combines N nano multilayer coatings, and in toughness tests, reference sample 3 (substrate 2 + reference coating Ti) was used. 0.33 Al 0.67 It did not demonstrate performance equal to or better than N).

Claims

[Claim 1] A coated cutting tool (1) comprising a cemented carbide base material (5) and a coating (6), The cemented carbide contains WC particles, eta phase particles, and a metal binder, the metal binder contains Co and Cr, the Co content in the cemented carbide is 6 to 14% by weight, the eta phase content is 1 to 10% by volume, the average particle size of the eta phase particles is 0.5 to 5 μm, and the Cr / Co weight ratio in the cemented carbide is 0.005 to 0.

025. - Coating (6) is Ti １－ｘ Al ｘ A first nanolayer (9) with N (0.35 ≤ x ≤ 0.70), and Ti １－ｙ Si ｙ A coated cutting tool (1) comprising a nanomultilayer structure (8) in which a second nanolayer (10) of N (0.12 ≤ y ≤ 0.25) is alternately stacked, wherein the sequence of one first nanolayer (9) and one second nanolayer (10) forms a layer period, and the average layer period thickness of the nanomultilayer (8) is ≤ 10 nm. [Claim 2] A coated cutting tool according to claim 1, wherein the Co content in the cemented carbide is 7 to 13% by weight. [Claim 3] A coated cutting tool according to claim 1 or 2, wherein the Cr / Co ratio in the cemented carbide is 0.010 to 0.

020. [Claim 4] A coated cutting tool according to any one of claims 1 to 3, wherein the eta phase content in the cemented carbide is 2 to 8 volume percent. [Claim 5] A coated cutting tool according to any one of claims 1 to 4, wherein the content of the eta phase in a portion of the substrate adjacent to the surface of the substrate corresponds to the content of the eta phase in the innermost part of the substrate. [Claim 6] Regarding the first nanolayer (9), Ti １－ｘ Al ｘ A coated cutting tool (1) according to any one of claims 1 to 5, wherein N (0.45 ≤ x ≤ 0.70). [Claim 7] The second nanolayer (10) is Ti １－ｙ Si ｙ A coated cutting tool (1) according to any one of claims 1 to 6, wherein N (0.14 ≤ y ≤ 0.23). [Claim 8] A coated cutting tool (1) according to any one of claims 1 to 7, wherein the average layer periodic thickness in the nanomultilayer (8) is 2 to 7 nm. [Claim 9] A coated cutting tool (1) according to any one of claims 1 to 8, wherein the nanolayer (8) has a columnar structure with an average column width of ≤ 100 nm. [Claim 10] A coated cutting tool (1) according to any one of claims 1 to 9, wherein the thickness of the nanolayer (8) is approximately 0.5 to approximately 15 μm. [Claim 11] A coated cutting tool (1) according to any one of claims 1 to 10, wherein the thickness of the nanolayer (8) is about 0.5 to about 5 μm. [Claim 12] A coated cutting tool (1) according to any one of claims 1 to 11, wherein the coating (6) comprises a layer (7) of TiN, (Ti,Al)N, or (Cr,Al)N located between a substrate and a nanomultilayer (8) having a thickness of about 0.1 to about 2 μm. [Claim 13] The innermost layer (7) is Ti １－ｚ The coated cutting tool (1) according to claim 12, wherein the outermost layer is AlzN (0.35 ≦ z ≦ 0.70). [Claim 14] The coated cutting tool (1) according to any one of claims 1 to 13, wherein the coated cutting tool (1) is a cutting tool insert, drill, or solid end mill for metalworking.

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