Cutting tool

Abstract

The present invention relates to a coated cutting tool comprising a substrate at least partially coated with a coating, the substrate being made of cemented carbide, the cemented carbide consisting of a hard constituent in a metallic binder, wherein the metallic binder comprises more than 60 wt% Ni, the coating comprising two or more layers, wherein the layer adjacent to the substrate is W(C x N 1‑x ) y layer, wherein 0.6≤x≤0.8 and 1.1≤y≤1.8, wherein W(C x N 1‑x ) y The layer thickness is 0.4-7 pm.

Description

Technical Field

[0001] This invention relates to a coated cutting tool. The cutting tool is CVD coated and the substrate is a cemented carbide, wherein the metal binder in the cemented carbide comprises Ni. The CVD coating is W(C) x N 1-x ) y The inner layer. Background Technology

[0002] CVD-coated cutting tools are well-known in the field of cutting tools used for metal-forming cutting operations. The substrate of coated cutting tools typically comprises cemented carbide, which is made of WC in a Co metal binder. Alternative binders containing no Co or small amounts of Co are being developed, but they are still rare or nonexistent in the market. Because of the interaction between the vapor phase and the cemented carbide, especially during chemical vapor deposition using reactive gases at high temperatures, high standards are required not only for the production of the cemented carbide itself but also for the coating used to coat it.

[0003] Among alternative metal binders, mixtures of Ni and Fe are promising candidates. Ni exhibits high reactivity with, for example, Ti, and high levels of Ni in cemented carbide lead to problems in the chemical vapor deposition of Ti-containing coatings due to the formation of intermetallic phases such as Ni3Ti at the interface between the cemented carbide and the coating, as well as within the coating itself. These intermetallic phases, such as Ni3Ti, at the interface or beneath the Ti-containing coating reduce coating adhesion and negatively impact the wear resistance of coatings subsequently deposited on top of the Ti-containing coating.

[0004] The paper "Chemical vapor deposition of TiN on transition metal substrates" by L. von Fieandt et al., Surface and Coatings Technology, Vol. 334 (2018), pp. 373-383, analyzes the problem of Ni3Ti formation during TiN coating deposition on Ni metal substrates. The conclusion is that excessive N2 partial pressure and low H2 partial pressure can reduce Ni3Ti formation during the CVD process.

[0005] One object of the present invention is to provide a cutting tool having a Ni-containing cemented carbide substrate having a wear-resistant CVD coating. Another object is to provide a method for depositing a coating comprising a 001-oriented α-Al2O3 layer on a Ni-containing cemented carbide substrate, particularly on a substrate containing a metal binder having more than 60% by weight of Ni. Summary of the Invention

[0006] At least one of the above objectives is achieved by the cutting tool according to claim 1. Preferred embodiments are disclosed in the dependent claims.

[0007] This invention relates to a coated cutting tool comprising a substrate at least partially coated with a coating, the substrate being made of cemented carbide consisting of a hard component in a metal binder, wherein the metal binder contains more than 60% by weight Ni, and the coating comprising two or more layers, wherein the layer adjacent to the substrate is W(C) x N 1-x ) y Layer, where 0.6≤x≤0.8 and 1.1≤y≤1.8, preferably 0.67≤x≤0.72 and 1.17≤y≤1.76, where W(C x N 1-x ) y The layer thickness is 0.4-7μm.

[0008] Carbide materials are used in demanding cutting tool applications due to their high hardness, high wear resistance, and high toughness. Carbide materials are produced by powder metallurgy, in which starting powders are mixed, ground, formed into green blanks, pre-sintered, and sintered.

[0009] Hard alloy materials typically consist of a hard component (WC) and optional carbides and / or nitrides such as TiC in a metal binder, for example, Co or Co and Ni and Fe. In this invention, the metal binder contains more than 60% by weight of Ni. It has been shown that a high Ni content in the metal binder is particularly desirable in CVD deposition. The composition of the hard alloy, especially the composition of the metal binder, can be analyzed by chemical analysis.

[0010] Surprisingly, W(C) having the aforementioned composition and a thickness of 0.4 μm or more was found to be effective. x N 1-x ) y The layer can prevent the negative impact of Ni in the metal binder on subsequently deposited layers. Therefore, the W(C) layer... x N 1-x ) y The layer functions as a diffusion barrier, preventing the substrate from affecting the coating quality. Therefore, W(C) with a layer thickness greater than 0.4 μm...x N 1-x ) y The layer can prevent the formation of reaction products between Ti and Ni.

[0011] When the coating is exposed to metal cutting applications that typically involve high pressure and high temperature, the W(C) of the present invention is considered to be effective. x N 1-x ) y (1.1≤1.1 exposed, preferably 1.17≤17.76) A large amount of C and N in the layer contributes to the stability of the layer.

[0012] In one embodiment of the present invention, the W(C) x N 1-x ) y The layer has a hexagonal phase. This is advantageous because the coefficient of thermal expansion of hexagonal W(C,N) is similar to that of WC. This may prevent the formation of hot cracks during the production of the coated cutting tool and may also affect tool life, as cutting tools are typically exposed to thermal cycling during use, such as in intermittent cutting. The hexagonal phase in this paper refers to the δ-WC hexagonal phase.

[0013] In one embodiment of the present invention, the W(C) x N 1-x ) y The layer is composed of columnar grains. "Columnar" here refers to a grain length-to-width ratio greater than one.

[0014] In one embodiment of the present invention, the W(C) x N 1-x ) y The average grain width of the layer is 0.14-0.40 μm, preferably 0.15-0.30 μm.

[0015] In one embodiment of the present invention, the W(C) x N 1-x ) y The layer in the W(C) x N 1-x ) y On the cross-section of the layer, and with a width of 100 μm and a height equal to the entire W(C) x N 1-x ) y The layer thickness analysis region exhibits the orientation measured by EBSD, wherein W(C) x N 1-x ) y The surface normal of the layer is parallel to the growth direction of the layer, wherein ≥75% of the analytical region has a surface normal similar to that of the W(C) layer. x N 1-x )y The surface normal of the layer is in the <11-20> direction within 30 degrees, preferably ≥80% of the analysis area is in the <11-20> direction within 30 degrees.

[0016] In one embodiment of the invention, the metal binder contains 65-90% by weight of Ni, preferably 70-87% by weight of Ni, and more preferably 75-85% by weight of Ni.

[0017] In one embodiment of the invention, the metal binder contains 10-20% by weight of Fe, preferably 10-15% by weight of Fe.

[0018] In one embodiment of the invention, the metal binder contains 3-8% by weight of Co, preferably 5-6% by weight of Co.

[0019] In one embodiment of the invention, the metal binder comprises 65-90 wt% Ni, 10-20 wt% Fe, and 3-8 wt% Co. In one embodiment, the metal binder is a Ni-Fe-Co alloy.

[0020] In one embodiment of the invention, the content of the metal binder in the cemented carbide is 3-20% by weight, preferably 5-15% by weight, and most preferably 5-10% by weight.

[0021] In one embodiment of the invention, the coating comprises a TiN layer and the thickness of the TiN layer is 0.3-1 μm.

[0022] In one embodiment of the present invention, the coating comprises a TiCN layer and the thickness of the TiCN layer is preferably 6-12 μm.

[0023] In one embodiment of the invention, the TiCN layer exhibits a texture coefficient TC(hkl) as defined by the Harris formula, measured by X-ray diffraction using Cu Kα radiation and θ-2θ scanning:

[0024]

[0025] Where I(hkl) is the measured intensity (integrated area) of the reflection of (hkl), I0(hkl) is the standard intensity according to ICDD PDF card 42-1489, n is the number of reflections, and the reflections used in the calculation are (1 1 1), (2 0 0), (2 2 0), (3 11), (3 3 1), (4 2 0), (4 2 2) and (5 1 1), where TC(4 2 2) is ≥3.5.

[0026] In one embodiment of the present invention, the total thickness of the coating is 2-25 μm.

[0027] In one embodiment of the invention, the coating further comprises a layer of Al2O3, preferably located on the outermost surface of the cutting tool and W(C) x N 1-x ) y Between layers.

[0028] In one embodiment of the present invention, the Al2O3 layer is an α-Al2O3 layer.

[0029] In one embodiment of the invention, the α-Al2O3 layer exhibits a texture coefficient TC(hkl) as defined by Harris's formula, measured by X-ray diffraction using Cu Kα radiation and θ-2θ scanning, where I(hkl) is the measured intensity (integrated area) of the (hkl) reflection, I0(hkl) is the standard intensity according to ICDD PDF card 00-010-0173, n is the number of reflections used in the calculation, wherein the (hkl) reflections used are (1 0 4), (1 1 0), (1 1 3), (0 24), (1 1 6), (2 1 4), (3 0 0), and (0 0 12), characterized in that TC(0 0 12) ≥ 7, preferably ≥ 7.2.

[0030] In one embodiment of the present invention, the thickness of the Al2O3 layer is 4-8 μm.

[0031] In one embodiment of the invention, the cutting tool is a drill bit, a milling cutter, or a turning insert, preferably a turning insert.

[0032] In one implementation, the W(C) x N 1-x ) y The layer is a CVD layer. In one embodiment, the TiCN layer is a CVD layer. In one embodiment, the Al2O3 layer is a CVD layer. In one embodiment of the present invention, the coating is a CVD coating.

[0033] Other objects and features of the invention will become apparent from the following definitions and examples taken in conjunction with the accompanying drawings.

[0034] method

[0035] W(C x N 1-x ) y Composition of layers -

[0036] W(C x N 1-x ) yThe elemental composition of the layer was determined by using 36 MeV at an incident angle of 67.5° relative to the surface normal and a recoil detection angle of 45°. 127 I 8+ The analysis was performed using Time-of-Flight Elastic Recoil Detection and Analysis (ToF-ERDA). A gas ionization chamber detector detected the scattered... 127 I 8+ The analysis detects the number and energy of ions, but more importantly, it also detects recoil atoms in the sample. This analysis is combined with a time-of-flight analyzer, which, along with energy detection, can calculate atomic mass. This allows for the determination of the elemental depth distribution of the coating.

[0037] Data analysis was performed using Potku software. This involved analyzing samples at a distance of approximately 30-200 nm from the sample surface, using a 250×10⁻⁶ pixel size. 15 -2000×10 15 atoms / cm 2 The concentration is calculated by integrating the depth distribution between the points.

[0038] W(C x N 1-x ) y Phase analysis of layers -

[0039] In order to analyze W(C) x N 1-x ) y The phase composition of the grains in the layer was measured by grazing incidence X-ray diffraction (GI-XRD). An incident angle of 1° was used. A Cu Kα source was used to provide a parallel incident beam. GI-XRD measurements were performed using a Philips MRD X'Pert diffractometer. A mirror slit allowing a 1.4 mm beam was used, with a 0.04 radsoller slit placed on the main beam side. The secondary beam was collimated using a 0.27° collimator, and the intensity was recorded using a proportional detector. Sample height and 0° tilt were aligned by applying z, ω-, and fine z scans using a straight beam. The beam intensity was reduced during alignment using a Cu / Ni manual beam attenuator, and the mirror slit was also reduced to give a beam size of 0.09 mm. A parallel plate collimator receiving slit was inserted to select a single-channel secondary beam collimator for alignment.

[0040] W(C x N 1-x ) y Grain width and orientation of the layer

[0041] Electron backscatter diffraction (EBSD) analysis was used to analyze the W(C) x N 1-x ) y The grain width, orientation, or texture of the layer.

[0042] The polished cross-sections were prepared as follows: Each CNMG120408-PM blade was mounted in black conductive phenolic resin from AKASER and then ground down approximately 1 mm, followed by two-step polishing: coarse polishing (9 μm) and fine polishing (1 μm) using a diamond slurry solution. Final polishing was performed using a colloidal silica solution. All samples were mounted in pre-tilted holders at a 70° angle to ensure maximum data acquisition efficiency. During data analysis, the coordinate system was aligned to correct for misalignment in the microscope.

[0043] For all EBSD measurements, grains from the WC-Co matrix were removed from the data to ensure that all acquired data originated from W(C)-Co. x N 1-x ) y Coating. Regions with a width of at least 100 μm and a height equal to the entire layer thickness were analyzed in 50 nm increments. Speed ​​1 binning mode (622 × 512 pixels) was used for all EBSD studies. In grain width measurements, at least 700 grains were used for each measurement.

[0044] The W(C) x N 1-x ) y The orientation of the layer was determined to be the W(C) in the analytical sample. x N 1-x ) y The quantity is expressed as a percentage (%), and the quantity is within a certain angular deviation from the set axis. <11-20>W(C x N 1-x ) y The direction is chosen to be parallel to the surface normal. W(C) x N 1-x ) y The orientation of the layer is calculated as <11-20>W(C x N 1-x ) y The analysis area has a directional deviation of ≤30°. An automatic cleaning step is used to gently reduce the noise level of the data. Then, according to the stated W(C)... x N 1-x ) y The layer has a cross-section and a width of 100 μm and a height equal to the entire W(C) x N 1-x ) y W(C) is defined by EBSD results over the analysis area of ​​the layer thickness. x N 1-x ) y The orientation of the layer, where W(C) x N 1-x ) yThe surface normal of the layer is parallel to the growth direction of the layer, wherein ≥75% of the analytical region has a surface normal similar to W(C). x N 1-x ) y The surface normal of the layer is in a <11-20> direction within 30 degrees, and preferably ≥80% of the analytical region has a direction consistent with W(C). x N 1-x ) y The surface normal of the layer is in the <11-20> direction within 30 degrees.

[0045] The W(C) was analyzed using the same EBSD measurement area mentioned in the previous section. x N 1-x ) y The average grain width was measured using the Aztec Crystal v.2.0 software package, which fits the small-diameter grain size of an ellipse. Each grain is fitted with an ellipse, and the small diameter of each ellipse is determined as the grain width. An automatic cleaning step is used to gently reduce the noise level of the data, discarding all grains with an area <5 pixels to ensure that measurement noise is not included, thereby improving measurement accuracy. The grain threshold is set to 10°.

[0046] The reference diagram in WC, Acta Crystallographica A (Acta Crystallogr), [ACCRA9], 1961, Vol. 14, pp. 200-201, is used for EBSD measurements of W(C). x N 1-x ) y The measurement used 53 reflectors.

[0047] A Zeiss Supra 55VP equipped with an Oxford Symmetry EBSD detector was used for all EBSD measurements. The accelerating voltage was set to 20 kV, and a probe current of 10–30 nA was used.

[0048] SEM study:

[0049] SEM studies were performed using a Zeiss Supra 55VP microscope. The accelerating voltage was 3 kV and the probe current was 300 pA.

[0050] Orientation of TiCN and α-Al2O3 layers

[0051] To investigate the orientation of the TiCN and alumina layers, X-ray diffraction was performed on the flank face of a cutting tool insert using a PANalyticalCubiX3 diffractometer equipped with a PIXcel detector. The coated cutting tool insert was mounted in a sample holder, ensuring that the flank face of the insert was parallel to the reference surface of the sample holder and at an appropriate height. Measurements were performed using Cu Kα radiation at a voltage of 45 kV and a current of 40 mA. A 1 / 2-degree anti-scattering slit and a 1 / 4-degree diverging slit were used. The diffraction intensity from the coated cutting tool was measured in the range of 20° to 140°2θ, i.e., in the range of incident angle θ from 10° to 70°.

[0052] Data analysis was performed using Panalytic's X'Pert HighScore Plus software, including background subtraction, Cu Kα2 removal, and distribution fitting. A general description of the fitting process is given below. Then, using the Harris formula (1) described above, the texture coefficient of the layer was calculated by comparing the ratio of measured intensity data to standard intensity data using the output of the program (the integral peak area of ​​the distribution fitting curve) based on the PDF card of the specific layer (e.g., TiCN or α-Al2O3 layer). Because the layer thickness is finite, the relative intensity of a pair of peaks at different 2θ angles differs from that of a bulk sample due to the varying path lengths through the layer. Therefore, when calculating the TC value, the linear absorption coefficient of the layer is also considered to perform a thin-film correction on the integral peak area intensity of the extracted distribution fitting curve. Since possible additional layers above, for example, the α-Al2O3 layer will affect the X-ray intensity entering the α-Al2O3 layer and leaving the entire coating, the linear absorption coefficients of the compounds in the layer also need to be considered and corrected accordingly. The same applies to X-ray diffraction measurements of the TiCN layer if it is located below, for example, the α-Al2O3 layer. Alternatively, another layer, such as TiN, above the alumina layer can be removed by methods that do not substantially affect XRD measurement results, such as chemical etching.

[0053] The texture coefficient TC(hkl) of the columnar grains in the TiCN layer was calculated according to the Harris formula for different growth directions.

[0054]

[0055] Where I(hkl) is the measured (integral area) intensity of the (hkl) reflection, I0(hkl) is the standard intensity according to ICDD PDF card No. 42-1489, and n is the number of reflections used in the calculation. In this case, the (hkl) reflections used are (1 1 1), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0), (4 2 2), and (5 1 1).

[0056] To investigate the texture of the α-Al₂O₃ layer, X-ray diffraction was performed using Cu Kα radiation, and the texture coefficient TC(hkl) for different growth directions of the columnar grains in the α-Al₂O₃ layer was calculated according to the Harris formula, where I(hkl) = the measured (integral area) intensity of the (hkl) reflection, I₀(hkl) = the standard intensity according to ICDD PDF card No. 00-010-0173, and n = the number of reflections used in the calculation. In this case, the (hkl) reflections used were: (1 0 4), (1 1 0), (1 1 3), (0 24), (1 1 6), (2 1 4), (3 0 0), and (0 0 12). Before calculating the texture coefficient, the measured integral peak area was corrected for thin films, and any additional layers above (i.e., on top) the α-Al₂O₃ layer were also corrected.

[0057] It should be noted that peak overlap is a phenomenon that can occur in X-ray diffraction analysis of coatings containing, for example, several crystalline layers and / or deposited on a matrix containing crystalline phases, and this phenomenon must be considered and compensated for. Peak overlap between the α-Al₂O₃ layer and the TiCN layer may affect the measurement and needs to be taken into account. It should also be noted that, for example, WC in the matrix and W(C) in the coating... x N 1-x ) y It may also have diffraction peaks that could affect the measurement and need to be taken into account. Attached Figure Description

[0058] Embodiments of the present invention will be described with reference to the accompanying drawings, wherein:

[0059] Figure 1 This illustrates the W(C) of a coated cutting tool according to an embodiment of the present invention. x N 1-x ) y Cross-sectional SEM micrograph of layer (sample E1), showing W(C) x N 1-x ) y Layer (1), substrate (2), TiCN layer (3) and α-Al2O3 layer;

[0060] Figure 2 yes Figure 1 EBSD band contrast micrograph of the coated cutting tool shown, in which W(C) is displayed. x N 1-x ) y Layer (1), substrate (2), TiCN layer (3) and α-Al2O3 layer;

[0061] Figure 3 yes Figure 1 The W(C) of the coated cutting tool shown x N 1-x ) y Close-up of the layer;

[0062] Figure 4 It shows that the coating of the cutting tool (sample C) is too thin according to the reference. x N 1-x ) y Cross-sectional SEM micrographs of the layers; and

[0063] Figure 5 This is the grazing incidence X-ray diffraction pattern of sample E1. The dashed lines indicate the peak positions of the δ-WC reference (from Z. Anorg. Allg. Chem., 1926, Vol. 156, pp. 27-36), and the numbers indicate the crystal planes to which the peaks belong. The intensity scale is logarithmic, thus enhancing the lower intensity peaks. The diffraction pattern shows that only the hexagonal δ-WC phase exists in the coating. Example

[0064] Embodiments of the invention will be disclosed in more detail with reference to the following examples. These examples are to be considered illustrative rather than limiting. In the following examples, coated cutting tools (blades) are manufactured, analyzed, and evaluated in cutting tests.

[0065] matrix

[0066] A cemented carbide matrix with an alternative binder, referred to herein as NiFeCo binder, is manufactured using a binder comprising approximately 80.7 wt% Ni, 13.7 wt% Fe, and 5.6 wt% Co. The binder content in the cemented carbide is approximately 7 wt%. The cemented carbide matrix with the alternative binder is manufactured from a powder mixture comprising approximately 6.09 wt% Ni, 1.02 wt% Fe, 0.039 wt% Co, 1.80 wt% Ti, 2.69 wt% Ta, 0.41 wt% Nb, 0.09 wt% N, and the balance WC. The powder mixture is ground, dried, pressed, and sintered at 1450 °C. As measured under an optical microscope, the sintered cemented carbide matrix comprises a substantially cubic carbide-free, binder-rich surface region extending approximately 30 μm from the matrix surface to the bulk depth. The carbon content in the powder was approximately 6.07 wt%, while the carbon content measured in the chemical analysis of the sintered cemented carbide was approximately 5.87 wt%. The sintered cemented carbide contained approximately 0.4 wt% Co, 1.0 wt% Fe, and 5.9 wt% Ni. The Co primarily originated from the abrasive media worn during the grinding process. No visible free graphite or η phase was observed in the SEM micrograph of the cross-section of the cemented carbide matrix.

[0067] For reference, a cemented carbide matrix with Co in a metal binder (referred to herein as the Co binder) was prepared from a powder mixture comprising approximately 7.20 wt% Co, 1.80 wt% Ti, 2.69 wt% Ta, 0.41 wt% Nb, 0.09 wt% N, and the balance WC. The powder mixture was milled, dried, pressed, and sintered at 1450 °C. As measured under an optical microscope, the sintered cemented carbide matrix contained a Co-rich surface region, substantially free of cubic carbides, extending from the matrix surface to a depth of approximately 23 μm. The sintered cemented carbide matrix contained approximately 7.2 wt% Co. No visible free graphite or η phase was observed in the SEM micrograph of the cross-section of the cemented carbide matrix. These matrices, free from Ni diffusion-related issues, are included herein as a reference.

[0068] The geometry of the cemented carbide matrix is ​​ISO type CNMG120408 for turning.

[0069] Coating deposition

[0070] CVD coatings were deposited on two cemented carbide compositions. Prior to coating deposition, each substrate was cleaned in a gentle sandblasting step to remove the outermost metal layer from the surface. Shortly before deposition, the substrates were cleaned in an ethanol bath for 30 minutes.

[0071] The deposition of W(C) in a hot-walled horizontal tubular furnace reactor is described in detail in J. Gerdin Hulkko, Muspel and Surtr: CVD system and control program for WF6 chemistry, dissertation, monograph, Uppsala University, 2019. x N 1-x ) y Layers. The main features of the reactor system are described here. The tubes are made of ferritic iron-chromium-aluminum alloy from Kanthal Ltd. An inner tube made of isotropic graphite protects the outer tube from severe corrosion and has an inner diameter of 47 mm. The tubes have a 175 mm long cold zone before reaching the furnace. The furnace has a 130 mm unheated zone, followed by three separate heated zones of 250 mm, 500 mm, and 250 mm, and finally a 130 mm unheated zone. The temperature of the heated zones is controlled by a Eurotherm 3216 PID controller, with K-type thermocouples placed at the center of each zone outside the reactor tubes and inside the furnace. The internal temperature of the central zone is calibrated using K-type thermocouples inserted through a 3 mm O-ring seal. During these processes, the three heated zones are maintained at the same temperature.

[0072] For WF6 (5.5% purity), H2 (5.6% purity), and Ar (6.0% purity), the precursor flow rate is controlled by an MKS GM50A mass flow controller, while for CH3CN (>99.9% purity), it is controlled by an MKS 1152C mass flow controller maintained at 40°C. The CH3CN evaporator cylinder is maintained at 25°C, and the piping between the cylinder and the mass flow controller is maintained at 45°C. All other gases are kept in cylinders at room temperature. Gases are transported in 316 stainless steel tubing, and silver-plated VCRs or copper gaskets are used at the connections. A large volume of gas (H2 diluted with Ar) enters the reactor tubes directly from the front of the reactor. The other two precursors (WF6 containing Ar and CH3CN containing Ar) are transported in separate Inconel 600 tubing through the first heating zone and into the central heating zone 25 mm inside the reactor tubes. Low pressure is maintained by an Ebara Technologies S20N Roots pump (maximum capacity 100 m³). 3 / hour, ultimate pressure 3.75×10 -2 The gas flow rate is throttled by an O-ring sealed butterfly valve (MKS153D) and regulated by a PID vacuum control system (MKS 946). Pressure is measured using a 1 Torr full-range temperature-stable capacitive pressure gauge (MKS627B). Pressure readings are calibrated by pumping the system to a high vacuum range using a turbomolecular pump.

[0073] The deposition zone is 90-230 mm away from the gas mixing point, in which a coating with uniform thickness, identical crystal phase, and identical main texture can be obtained.

[0074] W(C x N 1-x ) y Deposition was performed at 715 °C and 133 Pa using 1.8 vol% WF6, 1.2 vol% CH3CN, 25 vol% H2, and the balance Ar. The total gas flow rate was set to 350 sccm and the deposition rate was set to approximately 0.5 μm per hour.

[0075] Subsequently, samples C, D, E1, E2, F, and G are moved to deposit additional layers in a radial Ionbond Bernex™ CVD apparatus 530, which is large enough to accommodate 10,000 half-inch cutting blades.

[0076] First, a TiN layer was coated onto the substrate using TiCl4, N2, and H2 at 885℃. The TiN deposition time was adjusted to achieve a total TiN layer thickness of 0.4 μm.

[0077] Subsequently, an approximately 8 μm TiCN layer was deposited at 885 °C using the well-known MTCVD technique with TiCl4, CH3CN, N2, HCl, and H2. The TiCl4 / CH3CN volume ratio was 6.6 in the initial phase of the TiCN layer MTCVD deposition, followed by a period with a TiCl4 / CH3CN ratio of 3.7. Details of the TiN and TiCN deposition are shown in Table 1.

[0078] Table 1. MTCVD of TiN and TiCN

[0079]

[0080] After depositing the TiCN outer layer, the temperature was increased from 885°C to 1000°C in an atmosphere of 75 vol% H2 and 25 vol% N2.

[0081] A 0.7–2 μm thick bonding layer was deposited on top of an MTCVD TiCN layer at 1000 °C through a process consisting of four separate reaction steps. The first step was an MTCVD TiCN step using TiCl4, CH4, N2, HCl, and H2 at 400 mbar; the second step (TiCNO-1) used TiCl4, CH3CN, CO, N2, and H2 at 70 mbar; the third step (TiCNO-2) used TiCl4, CH3CN, CO, N2, and H2 at 70 mbar; and the fourth step (TiN-3) used TiCl4, N2, and H2 at 70 mbar. During the third deposition step, the CO gas flow rate increased linearly from the initial value to the stop value, as shown in Table 2. All other gas flow rates remained constant, but the concentration of all gases was affected due to the increase in the total gas flow rate. The bonding layer was oxidized for 4 minutes in a mixture of CO2, CO, N2, and H2 before the subsequent Al2O3 nucleation began.

[0082] Details of the bonding layer deposition are shown in Table 2.

[0083] Table 2. Deposition of the bonding layer

[0084]

[0085] An α-Al₂O₃ layer was deposited on top of the bonding layer. All α-Al₂O₃ layers were deposited in two steps at 1000 °C and 55 mbar. The first step used 1.2 vol% AlCl₃, 4.7 vol% CO₂, 1.8 vol% HCl, and the balance H₂ to give an α-Al₂O₃ layer of approximately 0.1 μm, and the second step, as described below, gave a total α-Al₂O₃ layer thickness of approximately 5 μm. The second step used 1.16% AlCl₃, 4.65% CO₂, 2.91% HCl, 0.58% H₂S, and the balance H₂ to deposit the α-Al₂O₃ layer.

[0086] Samples F and G also have an outermost wear indicator layer of TiN.

[0087] Table 3 provides a summary of the samples.

[0088] Table 3. Sample Summary

[0089]

[0090] Coating analysis

[0091] W(C) was determined on a reference sample using ERDA. x N 1-x ) yThe layer is composed of 43.7 atomic% W, 39.2 atomic% C, and 17.1 atomic% N, which corresponds to the chemical formula W(C). 0.7 N 0.3 ) 1.3 .

[0092] The W(C) was analyzed using grazing incidence X-ray diffraction. x N 1-x ) y The diffraction pattern shows that only the hexagonal phase exists in the coating, and no cubic WC phase was identified. 1-x or WN y (0.5≤y≤2) Reflection was not detected in the tungsten-rich W₂C phase (with a hexagonal close-packed W sublattice and C atoms occupying half of the octahedral pores). Reference reflection was calculated by Z. Anorg. Allg. Chem., 1926, Vol. 156, pp. 27-36.

[0093] Studying W(C) in SEM x N 1-x ) y Layer, W(C) has been discovered x N 1-x ) y The grains are columnar. In the matrix and W(C) x N 1-x ) y At the interface of the layer or in W(C) x N 1-x ) y No η phase was found within any of the layers. For reference samples B1 and B2, η phase was found at the interface with the matrix and within the TiN and TiCN layers.

[0094] Analyzing W(C) using EBSD x N 1-x ) y The average grain width and orientation of the layers are shown in Table 4.

[0095] Table 4. W(C) x N 1-x ) y Layer details

[0096]

[0097] Because of the symmetry of the hexagonal δ-WC phase, the result can be explained as follows: within a range of ±30°, it includes the area perpendicular to... <0001> All possible crystallographic directions. The chosen spacing also implies that within the grain... <0001> The maximum angle between the direction of the surface and the substrate surface is 30°. Therefore, the texture of the coating can be described as a hexagonal prism, where its... <0001> The orientation should preferably be parallel to the substrate surface or slightly inclined to the substrate surface.

[0098] The texture coefficients TC(hkl) of the TiCN and α-Al2O3 layers were analyzed as described above using X-ray diffraction with Cu Kα radiation and θ-2θ scanning. TC(0 0 12) and TC(4 2 2) are shown in Table 5.

[0099] Table 5: Texture Coefficient of Outer Layer

[0100] sample TC(4 2 2) of TiCN layer <![CDATA[TC(0 0 12) of α-Al2O3 layer]]> A 4.06 7.62 B1 2.19 5.62 B2 1.92 4.81 C 1.90 4.66 D 4.85 7.71 E1 4.96 7.74 E2 4.98 7.70 F 5.45 7.78 G 5.79 7.82

[0101] X-ray diffraction analysis and texture coefficients lead to the conclusion that, with a W(C) wavelength of approximately 640 nm, x N 1-x ) y Compared to sample D of the present invention, the layer has a W(C) layer of approximately 250 nm. x N 1-x ) y The reference sample C in the layer showed a lower TC (4 2 2) and a lower TC (0 0 12).

[0102] Cutting test

[0103] The following cutting data were used to conduct longitudinal turning tests on a cutting tool coated with ISO type CNMG120408 in ball bearing steel (100CrMo7-3);

[0104] Cutting speed v c 220m / minute

[0105] Cutting feed, f: 0.3 mm / revolution

[0106] Depth of cut, a p 2mm

[0107] Use a water-miscible metal working fluid.

[0108] Evaluate one cutting edge for each cutting tool.

[0109] When analyzing crater wear, the area of ​​exposed substrate was measured using an optical microscope. When the exposed substrate surface area exceeded 0.2 mm... 2 When the tool's lifespan was considered reached, the wear of each cutting tool was evaluated after 2 minutes of cutting under an optical microscope. Then, cutting operations were continued for 2 minutes after each run, while measurements were taken, until the tool's lifespan standard was reached. When the crater area exceeded 0.2 mm... 2The time to reach the cutting tool life standard was estimated based on the assumed constant wear rate between the last two measurements. In addition to crater wear, flank wear was also monitored. Three parallel tests were performed for each type of coating. The results, presented as average tool life, are shown in Table 6.

[0110] Table 6. Cutting Test Results

[0111]

[0112] It can be concluded that, according to the present invention, W(C) is provided. x N 1-x ) y The E2 sample outperformed the reference sample B2. As expected, the reference sample A, which had no interfering Ni in the metal binder phase of the cemented carbide, also performed well.

[0113] Although the invention has been described in conjunction with several exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments; rather, it is intended to cover various variations and equivalent arrangements in the appended claims.

Claims

1. A coated cutting tool comprising a substrate at least partially coated with a coating, the substrate being made of cemented carbide comprising a hard component in a metal binder, wherein the metal binder comprises more than 60% by weight Ni, and the coating comprising two or more layers, wherein the layer adjacent to the substrate is W(C) x N 1-x ) y Layer, where 0.6≤x≤0.8 and 1.1≤y≤1.8, where W(C x N 1-x ) y The layer thickness is 0.4-7 µm.

2. The coated cutting tool according to claim 1, wherein the W(C) x N 1-x ) y The layers have a hexagonal phase.

3. The coated cutting tool according to claim 1 or 2, wherein the W(C) x N 1-x ) y The layer is composed of columnar grains.

4. The coated cutting tool according to claim 1 or 2, wherein the W(C) x N 1-x ) y The average grain width of the layer is 0.14–0.40 µm.

5. The coated cutting tool according to claim 1 or 2, wherein the W(C) x N 1-x ) y The layer in the W(C) x N 1-x ) y On the cross-section of the layer, and with a width of 100 µm and a height of the entire W(C) x N 1-x ) y The layer thickness analysis region exhibits the orientation measured by EBSD, wherein W(C) x N 1-x ) y The surface normal of the layer is parallel to the growth direction of the layer, wherein ≥75% of the analytical region has a surface normal similar to that of the W(C) layer. x N 1-x ) y The surface normal of the layer is in the <11-20> direction within 30 degrees.

6. The coated cutting tool according to claim 1 or 2, wherein the metal binder comprises 65-90% by weight of Ni.

7. The coated cutting tool according to claim 1 or 2, wherein the metal binder content in the cemented carbide is 3-20% by weight.

8. The coated cutting tool according to claim 1 or 2, wherein the coating comprises a TiCN layer with a thickness of 6-12 µm.

9. The coated cutting tool according to claim 8, wherein the TiCN layer exhibits a texture coefficient TC(hkl) as defined by Harris's formula, measured by X-ray diffraction using Cu Kα radiation and θ-2θ scanning: Where I(hkl) is the measured intensity of the reflection of (hkl) in terms of integrated area, I0(hkl) is the standard intensity according to ICDD PDF card 42-1489, n is the number of reflections, and the reflections used in the calculation are (1 1 1), (2 0 0), (2 2 0), (3 11), (3 3 1), (4 2 0), (4 2 2) and (5 1 1), where TC(4 2 2)≥3.

5.

10. The coated cutting tool according to claim 1 or 2, wherein the total thickness of the coating is 2-25 µm.

11. The coated cutting tool according to claim 1 or 2, wherein the coating further comprises a layer located on the outermost surface of the cutting tool and W(C) x N 1-x ) y Al2O3 layers between the layers.

12. The coated cutting tool according to claim 11, wherein the Al2O3 layer is an α-Al2O3 layer.

13. The coated cutting tool according to claim 12, wherein the α-Al2O3 layer exhibits a texture coefficient TC(hkl) as defined by Harris's formula, measured by X-ray diffraction using Cu Kα radiation and θ-2θ scanning, where I(hkl) is the measured intensity of the (hkl) reflection in terms of integrated area, I0(hkl) is the standard intensity according to ICDD PDF card 00-010-0173, n is the number of reflections used in the calculation, wherein the (hkl) reflections used are (1 0 4), (1 10), (1 1 3), (0 2 4), (1 1 6), (2 1 4), (3 0 0), and (0 0 12), characterized in that TC(0 0 12)≥5.

14. The coated cutting tool according to claim 11, wherein the thickness of the Al2O3 layer is 4-8 µm.

15. The coated cutting tool according to claim 1 or 2, wherein the coating is a CVD coating.

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