Coated cutting tools

Abstract

This invention relates to a cutting tool comprising a substrate at least partially coated with a coating, said substrate being a cemented carbide, cermet, or ceramic, said coating comprising a Ti(C,N) layer, an Al2O3 layer, and a bonding layer therebetween. The Ti(C,N) layer is composed of columnar grains, wherein the average grain size D of said Ti(C,N) layer is... 422 The size is 25-50 nm, and the Ti(C,N) layer includes a B1 portion adjacent to the bonding layer, and the average grain size of the Ti(C,N) grains in the B1 portion is larger than the average grain size D of the entire Ti(C,N) layer. 422 In the B1 portion of the Ti(C,N) layer, the average grain size of the Ti(C,N) grains is 140-300 nm.

Description

Technical Field

[0001] The present invention relates to a coated cutting tool comprising a substrate and a coating, wherein the coating is deposited by CVD and comprises a Ti(C,N) layer and an α-Al2O3 layer. Background Technology

[0002] Coated cutting tools are well-known in the metal cutting industry. CVD-coated and PVD-coated cutting tools are the two most common types. These coatings offer advantages such as high chemical resistance and high wear resistance, which are important for achieving long tool life. CVD coatings containing Ti(C,N) layers as well as alumina layers are known to perform well in, for example, the turning or milling of steel.

[0003] EP2791387A1 discloses a cutting tool coated with a fine-grained titanium carbonitride layer. The coating offers advantages such as high resistance to spalling during turning of ductile iron and high-speed cutting. A columnar CVD TiCN layer with an average grain width of 0.05–0.4 μm is described.

[0004] Recent studies have shown that the combination of very fine-grained Ti(C,N) layers and Al2O layers can sometimes lead to poor adhesion between Ti(C,N) and Al2O3. Addressing this issue is of interest because very fine-grained Ti(C,N) has shown promising cutting tool properties.

[0005] One object of the present invention is to provide a coated cutting tool with high coating adhesion for metal cutting. Another object is to provide a coated cutting tool with high wear resistance, especially high resistance to spalling during metal cutting. A further object of the present invention is to provide a cutting tool with high resistance to crater wear in metal cutting of steel. Summary of the Invention

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

[0007] This invention relates to a cutting tool comprising a substrate at least partially coated with a coating comprising a Ti(C,N) layer, an Al2O3 layer, and a bonding layer therebetween, wherein the Ti(C,N) layer, having a thickness of 3-25 μm, is composed of columnar grains, wherein the average grain size D of the Ti(C,N) layer, as measured by X-ray diffraction using CuKα radiation, is... 422 The grain size D is 25-50 nm. 422It is calculated based on the Scherrer formula from the full width at half maximum (FWHM) of peak (422):

[0008]

[0009] Where D 422 Where is the average grain size of the Ti(C,N), K is the shape factor and is set to 0.9 here, and λ is the wavelength of CuKα radiation and is set to . B 422 The (422) is the FWHM value of the reflection, θ is the Bragg angle, wherein the Ti(C,N) layer includes a B1 portion adjacent to the bonding layer, and wherein the average grain size of the Ti(C,N) grains in the B1 portion is greater than the average grain size D over the entire thickness of the Ti(C,N) layer. 422 In the B1 portion of the Ti(C,N) layer, the average grain size of the Ti(C,N) grains measured within 0.5 μm of the bonding layer in the B1 portion of the Ti(C,N) layer is 140-300 nm, as measured by counting the number of grains along a line parallel to the surface of the substrate in a SEM micrograph at 15,000x magnification.

[0010] This invention provides increased adhesion between a very fine-grained Ti(C,N) layer and an α-Al₂O₃ layer. This increased adhesion is achieved by altering the deposition process conditions at the end of the Ti(C,N) deposition, causing some of the fine Ti(C,N) grains to widen and form coarser-grained Ti(C,N) portions. Subsequently, the process conditions are altered again, this time to provide an optimal outer surface for the Ti(C,N) grains. In this way, the outermost surface of the formed Ti(C,N) is similar to the outermost surface of the coarse-grained Ti(C,N), which is known to exhibit high adhesion to the α-Al₂O₃ layer via the bonding layer. If the average grain size in the B1 portion is too small, adhesion to the subsequently deposited α-Al₂O₃ layer will not increase. The average grain size in the B1 portion is suitably less than 300 nm, as this is advantageous for wear resistance.

[0011] Due to limited resolution, it is difficult to study the grain size of very fine-grained Ti(C,N) in SEM. Therefore, the average grain size of the fine-grained portion of the Ti(C,N) layer is instead defined via XRD and the Scherrer equation. Although the signal from XRD also includes information from the coarser-grained Ti(C,N)B1 portion, this contribution is considered limited.

[0012] On the other hand, the challenge of studying the grain size in the coarse-grained B1 portion is that it is only a part of the Ti(C,N) layer, thus requiring the selection of high-precision methods.

[0013] In one embodiment of the present invention, the thickness of the B1 portion of the Ti(C,N) layer, measured in the growth direction of the coating, is 0.5-1.5 μm, preferably 0.6-0.9 μm, and most preferably 0.6-0.8 μm.

[0014] Fine-grained Ti(C,N) is advantageous as a wear-resistant layer, likely due to its abundant grain boundaries or because the layer's thickness is smoother or more uniform. Therefore, the fine-grained portion of the TiCN layer should be relatively thick. The coarse-grained portion, which contributes to increased adhesion, should be relatively limited, with the thickness of the B1 portion preferably 0.5-1.5 μm, more preferably 0.6-0.9 μm, and most preferably 0.6-0.8 μm. If the B1 portion is too thin, the adhesion will not be enhanced.

[0015] In one embodiment of the invention, the bonding layer comprises at least one compound selected from titanium carbon oxides, titanium nitrides, and titanium carbon oxynitrides.

[0016] The advantage of the combined layer of titanium carbon oxide, titanium nitride and titanium carbon oxynitride is that it can provide an epitaxial relationship between the Ti(C,N) layer and the α-Al2O3 layer.

[0017] In one embodiment of the present invention, the grain size D of Ti(C,N) is... 422 The wavelength is 25-40nm, preferably 25-35nm.

[0018] This invention, which increases the adhesion between fine-grained Ti(C,N) and α-Al2O3 layers, is applicable to Ti(C,N) layers with very fine grains, for example, when the grain size D of Ti(C,N) is... 422 It is particularly advantageous when the wavelength is 25-40nm, or even 25-35nm.

[0019] In one embodiment of the invention, the Ti(C,N) layer exhibits an X-ray diffraction pattern measured using CuKα radiation and θ-2θ scanning, wherein TC(hkl) is defined according to the Harris formula:

[0020]

[0021] Where I(hkl) is the measured intensity (integrated area) of the reflection of (hkl), I0(hkl) is the standard intensity according to the ICDD PDF card No. 42-1489, n is the number of reflections, and the reflections used in the calculation are (1 1 1), (2 0 0), (2 20), (3 1 1), (3 3 1), (4 2 0) and (4 2 2), where TC(422)≥3, preferably ≥4.

[0022] In one embodiment of the present invention, the Al2O3 layer is an α-Al2O3 layer, preferably with an average thickness of 1 μm-15 μm, more preferably 3-10 μm.

[0023] In one embodiment of the invention, the layer, wherein the α-Al2O3 layer exhibits a texture coefficient TC(hkl) as defined by Harris's formula, measured by X-ray diffraction using CuKα 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 No. 00-010-0173, n is the number of reflections used in the calculation, and wherein the (hkl) reflections used are (1 04), (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) ≥ 7.5, preferably ≥ 7.7, more preferably ≥ 7.8.

[0024] In one embodiment of the invention, the layer, wherein the α-Al2O3 layer exhibits TC(110)≤0.2, preferably≤0.1.

[0025] In one embodiment of the invention, the average grain size of the Ti(C,N) grains in the B1 portion of the Ti(C,N) layer is 140 nm-175 nm. If the average grain size in the B1 portion is too large, the adhesion remains high, but it is found that the subsequently deposited α-Al2O3 layer cannot achieve the highest orientation.

[0026] In one embodiment of the present invention, the average thickness of the Ti(C,N) layer is 4-20 μm, preferably 5-15 μm.

[0027] In one embodiment of the present invention, the average thickness of the bonding layer is 0.25-2.5 μm, preferably 0.5-2.0 μm.

[0028] In one embodiment of the present invention, the average thickness of the coating is 5.0 μm-30.0 μm, preferably 10-20 μm.

[0029] In one embodiment of the present invention, the substrate is a cemented carbide, a cermet, or a ceramic.

[0030] The atomic ratio of carbon to the sum of carbon and nitrogen (C / (C+N)) in the Ti(C,N) layer of the present invention (measured by electron microprobe analysis) is preferably 0.50-0.65, more preferably 0.55-0.62.

[0031] Other objects and features of the invention will become apparent from the following definitions and embodiments considered in conjunction with the accompanying drawings.

[0032] definition

[0033] The term "cutting tool" in this document is intended to refer to cutting tools suitable for metal cutting applications, such as inserts, end mills, or drills. Applications may include, for example, turning, milling, or drilling of metals such as steel.

[0034] method

[0035] The average grain size of the Ti(C,N) layer, D 422

[0036] To investigate the average grain size of Ti(C,N) grains in the Ti(C,N) layer, X-ray diffraction (XRD) was performed on the flank face using a PANalytical CubiX3 diffractometer equipped with a PIXcel detector. The coated cutting tool was mounted in a sample holder, ensuring that the flank face of the sample was parallel to the reference surface of the sample holder and at an appropriate height. Cu-Kα radiation was used for measurements 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 within a 2θ range of 20° to 140°, i.e., from an incident angle θ range of 10° to 70°. Data analysis was performed using PANalytical's X'Pert HighScore Plus software, including background fitting, Cu-Kα2 removal, and distribution fitting.

[0037] The grain size of the layer was calculated using the integral full width at half maximum (FWHM) of the distribution fitting curve obtained from PANalytical's X'Pert HighScore Plus software, according to the Scherrer formula (Birkholz, 2006) (Eq1).

[0038] Average grain size D 422 The full width at half maximum (FWHM) of peak (422) is calculated using the Scherrer formula:

[0039]

[0040] Where D422 Where is the average grain size of the Ti(C,N), K is the shape factor and is set to 0.9 here, and λ is the wavelength of CuKα1 radiation and is set to . B 422 It is the FWHM value of the reflection (422), and θ is the Bragg angle, i.e., the incident angle.

[0041] The FWHM obtained from the measurements contains both broadening from the instrument and broadening caused by small grain size. To compensate for this, the Gaussian approximation is used (Birkholz, 2006). 422 It is the line width at FWHM after subtracting the instrument width increase (0.00174533 radians), and is defined in formula (2):

[0042] B 422 =√((FWHM) obs ) 2 -(FWHM ins ) 2 (2)

[0043] Among them B 422 It is a broadening (in radians) used for grain size calculation, FWHM obs It is the measured widening (in radians), FWHM ins It is an increase in instrument width (in radians).

[0044] Since other possible layers above the Ti(C,N) layer can affect the X-ray intensity entering the Ti(C,N) layer and leaving the entire coating, it is necessary to consider the linear absorption coefficients of the corresponding compounds in the layers to make corrections for these effects. Alternatively, other layers above the Ti(C,N) monolayer can be removed by methods such as chemical etching that do not substantially affect the XRD measurement results.

[0045] Grain size of the B1 portion of Ti(C,N)

[0046] In the uppermost region of the Ti(C,N) layer, in region B1, which is closest to the bonding layer that attaches the Al2O3 layer to the Ti(C,N) layer, the Ti(C,N) grains are enlarged to improve adhesion. Grain boundaries and grains are identified and counted along lines in a cross-sectional SEM micrograph, and the average grain size of the Ti(C,N) grains in this region is analyzed by dividing the length of the line by the number of grains.

[0047] The freshly coated blade was mounted in AKASERL's black conductive phenolic resin, then ground to 1 mm, followed by two-step polishing: coarse polishing (9 μm) using diamond slurry and fine polishing (1 μm). To observe the microstructure of the layer, the sample was further polished with colloidal silica suspension (MasterPolish 2). This polishing was performed until a scratch-free cross-section was obtained. The sample was then cleaned with deionized water and detergent to remove residual polishing suspension and dried with clean air spray.

[0048] The SEM used for grain size studies was a Carl Zeiss AG-Supra 40, operating at an accelerating voltage of 3 kV with a 30 μm aperture. SEM images were obtained at 15,000x magnification and a working distance of approximately 5 to 10 mm. Figure 1 As shown in the image, a horizontal line at least 7.5 μm long was drawn in the upper part of the B1 portion directly below the bonding layer on the SEM image, intersecting the Ti(C,N) grains. Grains crossing the horizontal line were counted, and the average grain size was calculated by dividing the length of the line by the number of grains, as given in Table 5. For better statistical analysis, grains crossing the horizontal line were counted in two distinct, randomly selected regions for each sample.

[0049] X-ray diffraction measurements of Ti(C,N) and Al2O3

[0050] To investigate the texture of the layer, X-ray diffraction was performed on the flank face of the cutting tool insert using a PANalytical CubiX3 diffractometer equipped with a PIXcel detector. The coated cutting tool insert was mounted in a sample holder, ensuring that the flank face of the cutting tool insert was parallel to the reference surface of the sample holder and that the flank face was at an appropriate height. Cu-Kα radiation was used for measurements 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 within a 2θ range of 20° to 140°, i.e., within an incident angle θ range of 10° to 70°.

[0051] Data analysis was performed using PANalytical's X'Pert HighScore Plus software, including background subtraction and Cu-K subtraction. α2Removal and distribution fitting. A general description of the fitting will be given later. The texture factor of the layer is then calculated by comparing the measured intensity data of a specific layer (e.g., Ti(C,N) or α-Al2O3 layer) with the standard intensity data according to the PDF card using the Harris formula (3) disclosed below, with the output from the program (the integral peak area of ​​the distribution fitting curve). Because the thickness of the layer is finite, the relative intensity of a pair of peaks at different 2θ angles differs from the relative intensity of peaks for a bulk sample due to the different path lengths through the layer. Therefore, when calculating the TC value, the linear absorption coefficient of the layer is also taken into account, and a thin film correction is applied to the extracted integral peak area intensity of the distribution fitting curve. Since other possible layers above, for example, the α-Al2O3 layer, may affect the X-ray intensity entering the α-Al2O3 layer and leaving the entire coating, the linear absorption coefficient of the corresponding compound in the layer also needs to be taken into account to correct for these. This also applies to X-ray diffraction measurements of the Ti(C,N) layer if the Ti(C,N) layer is located below, for example, the α-Al2O3 layer. Alternatively, other layers, such as TiN, above the alumina layer can be removed using methods that do not substantially affect XRD measurement results, such as chemical etching.

[0052] To study the texture of the α-Al2O3 layer, X-ray diffraction was performed using CuKα radiation, and the texture coefficient TC(hkl) of the columnar grains in different growth directions of the α-Al2O3 layer was calculated according to Harris's formula (3):

[0053]

[0054] 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 to be used in the calculation. The (hkl) reflections used in this case 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). Before calculating the ratio, the measured integral peak area is corrected for thin films and for any other layers above (i.e., on top) the α-Al2O3 layer.

[0055] The texture factor TC(hkl) of the columnar grains in different growth directions of the Ti(C,N) layer is calculated according to the previously published Harris formula (3), where I(hkl) is the measured (integrated 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 to be used in the calculation. The (hkl) reflections used in this case are (1 11), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0), and (4 2 2).

[0056] It should be noted that peak overlap is a phenomenon that can occur in X-ray diffraction analysis of coatings comprising, for example, several crystalline layers and / or deposited on a matrix containing a crystalline phase, and this must be taken into account and compensated for. The overlap of peaks from the α-Al₂O₃ layer with peaks from the Ti(C,N) layer may affect the measurements and needs to be considered. It should also be noted that, for example, WC in the matrix may have diffraction peaks close to the relevant peaks of this invention. Attached Figure Description

[0057] Embodiments of the present invention will be described with reference to the accompanying drawings, wherein:

[0058] Figure 1 A scanning electron microscope (SEM) image of a cross section of an example of the coating of the present invention (sample D) is shown, wherein the measurement of the amount of Ti(C,N) grains through a line parallel to the substrate is shown in section B1.

[0059] Figure 2 A scanning electron microscope (SEM) image of a cross-section of an example of the coating of the present invention (sample D) is shown, in which the B1 portion of the Ti(C,N) layer (1), the bonding layer (2), and the α-Al2O3 layer (3) are shown.

[0060] Figure 3 A scanning electron microscope (SEM) image of a cross-section of an example of the reference coating (sample A) is shown, in which the uppermost Ti(C,N) (1), the bonding layer (2), and the lowermost α-Al2O3 (3) are visible.

[0061] Figure 4 A scanning electron microscope (SEM) image of a cross-section of an example of the coating of the present invention (sample G) is shown, in which the B1 portion of the Ti(C,N) layer (1), the bonding layer (2), and the α-Al2O3 layer (3) are shown.

[0062] Figure 5A scanning electron microscope (SEM) image of a cross-section of an example of the reference coating (sample B) is shown, in which the uppermost Ti(C,N) (1), the bonding layer (2), and the lowermost α-Al2O3 (3) are visible.

[0063] Figure 6 The image shows a scanning electron microscope (SEM) image of the top surface of portion B1 of a sample having a Ti(C,N) layer corresponding to the Ti(C,N) in sample D, where the morphology of the outermost surface of portion B1 is visible.

[0064] Figure 7 The image shows a scanning electron microscope (SEM) image of the top surface of the Ti(C,N) layer in the sample having a Ti(C,N) layer corresponding to the Ti(C,N) in sample B, where the morphology of the outermost surface of the very fine-grained Ti(C,N) is visible.

[0065] Figure 8 The image shows a scanning electron microscope (SEM) image of the top surface of the Ti(C,N) layer of a sample having a Ti(C,N) layer corresponding to that in reference sample A, where the morphology of the outermost surface of the coarse-grained Ti(C,N) is visible.

[0066] Figure 9 This is a schematic overview showing the positions of the layers and portions of the present invention: Ti(C,N) layer (1), B1 portion of Ti(C,N) layer (1), bonding layer (2), α-Al2O3 layer (3) and substrate (4). Example

[0067] Exemplary embodiments of the present invention will now be disclosed in more detail and compared with reference embodiments. Coated cutting tools (blades) are manufactured and analyzed and tested in cutting experiments.

[0068] The cemented carbide matrix is ​​manufactured using conventional processes including grinding, mixing, spray drying, pressing, and sintering. The ISO type geometry of the cemented carbide matrix (insert tool) is CNMG-120408-PM. The cemented carbide composition is 7.2 wt% Co, 2.9 wt% TaC, 0.5 wt% NbC, 1.9 wt% TiC, 0.4 wt% TiN, and the remainder WC.

[0069] Prior to coating deposition, the substrate is exposed to a mild blasting process to remove any residues from the sintering process from the substrate surface.

[0070] CVD deposition

[0071] The sintered substrate was CVD coated in an Ionbond Type size 530 radial CVD reactor capable of accommodating 10,000 half-inch cutting blades. Samples for further testing and analysis were selected from the center of the chamber, at a position half the plate radius between the plate center and the periphery. A mass flow controller was selected to allow for setting a high flow rate, such as CH3CN.

[0072] A first innermost coating of approximately 0.2 μm TiN was deposited on all substrates at a process of 400 mbar and 885 °C. A gas mixture of 48.8 vol% H2, 48.8 vol% N2, and 2.4 vol% TiCl4 was used.

[0073] Subsequently, Ti(C,N) layers were deposited, with all samples AG deposited using different Ti(C,N) as follows. Reference sample A was deposited using process steps V and W as shown in Table 1. Before starting process step X, sample BG was temperature-conditioned from 885°C to 870°C in 50 vol% H2 and 50 vol% N2 at 80 mbar. The Ti(C,N) layer of reference sample B was deposited using process step X as shown in Table 1. On sample CG, Ti(C,N) layers were deposited using process steps X, Y, and Z, with deposition times as shown in Tables 1 and 2. Processing times were adjusted so that all samples achieved approximately the same total Ti(C,N) layer thickness.

[0074] Table 1

[0075]

[0076] Table 2

[0077]

[0078] A 0.7–0.9 μm thick bonding layer was deposited on top of the Ti(C,N) layer at 1000 °C via a process consisting of four independent reaction steps. The process consisted of: an 8-minute HTCCVD Ti(C,N) step using TiCl4, CH4, N2, HCl, and H2 at 400 mbar; a second step (Ti(C,N,O)-1) using TiCl4, CH3CN, CO, N2, and H2 at 70 mbar; a third step (Ti(C,N,O)-2) using TiCl4, CH3CN, CO, N2, and H2 at 70 mbar; and a final step (TiN) using TiCl4, N2, and H2 at 70 mbar for 6 minutes. During the third deposition step, as shown in Table 3, the CO gas flow rate increased linearly from the initial value to the final value. All other gas flow rates remained constant, but the concentrations of all gases were slightly affected due to the increased total gas flow rate. Before the subsequent Al2O3 nucleation begins, the bonding layer is oxidized in a mixture of CO2, CO, N2 and H2 for 4 minutes.

[0079] Detailed information on the bonding layer deposition is shown in Table 3.

[0080] Table 3 Deposition of the bonding layer

[0081]

[0082] 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 obtain approximately 0.1 μm of α-Al₂O₃, while the second step, disclosed below, yielded a total α-Al₂O₃ layer thickness of approximately 5 μm. The second step of depositing the α-Al₂O₃ layer used 1.16% AlCl₃, 4.65% CO₂, 2.91% HCl, 0.58% H₂S, and the balance H₂.

[0083] Coating analysis

[0084] The layer thickness was measured on the rake face of the cutting tool sample using a scanning electron microscope. The layer thickness of the coating on sample AG is shown in Table 4.

[0085] Table 4 Layer Thickness

[0086]

[0087] The grain size of the Ti(C,N) layer was analyzed by averaging the values ​​throughout the Ti(C,N) layer and in the B1 region near the bonding layer. The results are shown in Table 5.

[0088] The grain size of the Ti(C,N) layer in reference sample A was too large for XRD analysis, and the Scherrer formula was not considered valid for grain sizes larger than approximately 0.2 μm. The average grain size of this layer was measured to be greater than 200 nm in the cross-sectional SEM image.

[0089] Table 5 Grain sizes of Ti(C,N)

[0090]

[0091] (na = Unanalyzed)

[0092] The texture coefficients of the Ti(C,N) and α-Al2O3 layers were analyzed using X-ray diffraction, and the results are shown in Tables 6 and 7.

[0093] Table 6 Texture coefficients of the α-Al2O3 layer in the samples

[0094] A 0.02 0.25 0.01 0.07 0.01 0.03 0.00 7.61 B 0.00 0.01 0.00 0.00 0.00 0.00 0.00 7.99 C 0.02 0.03 0.00 0.01 0.01 0.00 0.00 7.94 D 0.01 0.07 0.00 0.02 0.00 0.00 0.00 7.89 E 0.01 0.08 0.00 0.02 0.01 0.00 0.00 7.89 F 0.09 0.09 0.00 0.03 0.06 0.01 0.01 7.70 G 0.03 0.17 0.00 0.05 0.03 0.01 0.00 7.72

[0095] Table 7 Texture coefficient TC(422) of Ti(C,N) layer in the sample

[0096] A 3.94 B 3.95 C 3.43 D 4.14 E 4.06 F 3.19 G 3.74

[0097] Performance test

[0098] In two parallel cutting tests (Cutting Test 1 and Cutting Test 2), freshly coated cutting tools were tested in longitudinal turning operations on OVAKO 825B (100CrMo7-3) high-alloy steel. The cutting speed Vc was 220 m / min, the feed rate fn was 0.3 mm / rpm, the depth of cut was 2 mm, and water-soluble cutting fluid was used. Machining continued until the end-of-life criteria were met. One cutting edge of each cutting tool was evaluated.

[0099] When the wear on the flank face is greater than 0.3 mm after one or two passes, or when the area of ​​the crater (exposed substrate) is greater than 0.2 mm. 2 When the tool life standard is met, it is considered to have been reached. Once any one of these standards is met, the sample is considered to have reached its lifespan. The results of the cutting tests are shown in Tables 8 and 9.

[0100] Table 8 Cutting Test 1

[0101]

[0102] Table 9 Cutting Test 2

[0103]

[0104] As shown in Table 8, all samples C, D, E, F, and G exhibit high wear resistance. As shown in Table 9, compared with the very high-performance reference sample (reference sample A), samples D and E show high resistance to flank wear and crater wear in metal cutting of steel.

[0105] The cutting tools were also evaluated by exposure to wet blasting. Blasting was performed on the rake face of the cutting tool. The blasting slurry consisted of water containing 20% ​​by volume alumina, with the rake face of the cutting insert at a 90° angle to the direction of the blasting slurry. The distance between the nozzle and the insert surface was approximately 145 mm. The pressure of the slurry on the blasting gun was 1.8 bar for all samples, while the air pressure was 2.2 bar. The alumina abrasive was F230 mesh (FEPA 42-2:2006). The average blasting time per unit area was 4.4 seconds. Samples B and C failed the wet blasting test; the coating of sample B showed severe peeling, and sample C showed pinpoint peeling. All other samples withstood the wet blasting test without damage to the coating.

[0106] While the invention has been described in conjunction with various exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments, but rather is intended to cover various modifications and equivalent arrangements as indicated in the appended claims. Furthermore, it should be recognized that any disclosed form or embodiment of the invention may be incorporated, as a general matter of design choice, into any other disclosed or described or suggested form or embodiment. Therefore, it is intended to be limited only by the scope indicated by the appended claims.

Claims

1. A cutting tool comprising a substrate at least partially coated with a coating, said coating comprising a Ti(C,N) layer, an Al2O3 layer, and a bonding layer therebetween, wherein The Ti(C,N) layer, with a thickness of 3-25 µm, is composed of columnar grains, wherein the average grain size D of the Ti(C,N) layer, as measured by X-ray diffraction using CuKα radiation, is... 422 The average grain size D is 25-50 nm. 422 It is calculated based on the Scherrer formula from the full width at half maximum (FWHM) of peak (422): Where D 422 Where is the average grain size of the Ti(C,N), K is the shape factor and is set to 0.9 here, λ is the wavelength of CuKα radiation and is set to 1.5405 Å here, B 422 It is the FWHM value of the reflection (422), where θ is the Bragg angle. The Ti(C,N) layer includes a B1 portion adjacent to the bonding layer, and the average grain size of the Ti(C,N) grains in the B1 portion is greater than the average grain size D over the entire thickness of the Ti(C,N) layer. 422 , In the B1 portion of the Ti(C,N) layer, the number of grains was measured by counting along a line parallel to the surface of the substrate in a SEM micrograph at 15,000x magnification. The average grain size of the Ti(C,N) grains within 0.5 µm of the bonding layer in the B1 portion of the Ti(C,N) layer was 140-300 nm. The thickness of the B1 portion of the Ti(C,N) layer is 0.5-1.5 µm.

2. The cutting tool according to claim 1, wherein the thickness of the B1 portion of the Ti(C,N) layer is 0.6-0.9 µm.

3. The cutting tool according to claim 1 or 2, wherein the bonding layer comprises at least one compound selected from titanium carbon oxide, titanium nitride, and titanium carbon oxynitride.

4. The cutting tool according to claim 1 or 2, wherein the average grain size D of the Ti(C,N) is... 422 It is 25-40nm.

5. The cutting tool according to claim 1 or 2, wherein the Ti(C,N) layer exhibits an X-ray diffraction pattern measured using CuKα radiation and θ-2θ scanning, wherein the texture coefficient TC(hkl) is defined according to the Harris formula: Where I(hkl) is the measured intensity of the reflection of (hkl), I0(hkl) is the standard intensity according to ICDD PDF card No. 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 1 1), (3 31), (4 2 0), and (4 2 2), where TC(422) ≥ 3.

6. The cutting tool according to claim 1 or 2, wherein the Al2O3 layer is an α-Al2O3 layer.

7. The cutting tool according to claim 6, wherein the average thickness of the α-Al2O3 layer is 1 µm-15 µm.

8. The cutting tool according to claim 6, wherein the α-Al₂O₃ layer exhibits a texture coefficient TC(hkl) as defined by Harris's formula, measured by X-ray diffraction using CuKα radiation and θ-2θ scanning. Where I(hkl) is the measured intensity of the (hkl) reflection, I0(hkl) is the standard intensity according to ICDD PDF card No. 00-010-0173, n is the number of reflections used in the calculation, and 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) ≥7.

5.

9. The cutting tool according to claim 6, wherein the α-Al2O3 layer exhibits a texture factor TC(110) ≤ 0.

2.

10. The cutting tool according to claim 1 or 2, wherein in the B1 portion of the Ti(C,N) layer, the average grain size of the Ti(C,N) grains is 140 nm-175 nm.

11. The cutting tool according to claim 1 or 2, wherein the average thickness of the Ti(C,N) layer is 4-20 µm.

12. The cutting tool according to claim 1 or 2, wherein the average thickness of the bonding layer is 0.25-2.5 µm.

13. The cutting tool according to claim 1 or 2, wherein the average thickness of the coating is 5.0 µm to 30.0 µm.

14. The cutting tool according to claim 1 or 2, wherein the substrate is cermet or ceramic.

15. The cutting tool according to claim 1 or 2, wherein the substrate is cemented carbide.

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