A coated cutting tool

Abstract

The present invention provides a coated cutting tool, belonging to the technical field of cutting tools. It solves the problem of the existing demand for coated cutting tools with wear resistance in metal cutting operations. This coated cutting tool is made of hard metal, cermet or ceramic substrate and multiple wear-resistant coatings. The multiple wear-resistant coatings are applied to the substrate by means of CVD method. The multiple wear-resistant coatings have a total thickness of 5 to 40 μm. The multiple wear-resistant coatings at least include a medium-temperature titanium carbonitride MT-TiCN layer, an α-Al2O3 layer and a transition layer deposited between the medium-temperature titanium carbonitride MT-TiCN layer and the α-Al2O3 layer. The present invention has the advantages of improving the tool durability, significantly improving the wear resistance of the coating, ensuring the stability of the tool service life and providing good deformation ability, and ensuring the impact resistance of the coating.

Description

Technical Field

[0001] The present invention belongs to the technical field of cutting tools and relates to a coated cutting tool. Background Art

[0002] Depositing thin refractory coatings on cutting tools has been widely used in the machining industry for decades. Coatings such as TiCN and Al2O3 have shown improved wear resistance of cutting inserts when cutting many different materials. A combination of an inner layer of TiCN and an outer layer of α-Al2O3 can be found on many commercially available cutting tools designed for turning or milling, for example, steel. However, with the development of technology, higher requirements are put forward for cutting tools. Therefore, there is a need for coated cutting tools having wear resistance in metal cutting operations. Summary of the Invention

[0003] The object of the present invention is to provide a coated cutting tool for metal chip forming machining, more precisely a coated cutting tool comprising a substrate coated with multiple wear-resistant coatings, in view of the above problems existing in the prior art.

[0004] The object of the present invention can be achieved by the following technical solutions: A coated cutting tool, characterized in that it is made of a hard metal, cermet or ceramic substrate and multiple wear-resistant coatings, the multiple wear-resistant coatings are applied to the substrate by means of a CVD method, the multiple wear-resistant coatings have a total thickness of 5 to 40 μm, and the multiple wear-resistant coatings at least comprise a medium-temperature titanium carbonitride MT-TiCN layer, an α-Al2O3 layer and a transition layer deposited between the medium-temperature titanium carbonitride MT-TiCN layer and the α-Al2O3 layer;

[0005] Wherein the α-Al2O3 has a texture coefficient TC(h k l) measured by X-ray diffraction using cuKa radiation and θ-2θ scanning and defined according to Harris' formula;

[0006]

[0007] where I(hkl) is the measured intensity (integrated area) of the (h k l) reflection; I0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 10-0173; n is the number of reflections used in the calculation and the (h k l) reflections used are (0 1 2), (1 0 4), (1 1 0), (1 1 3), (1 1 6), (2 1 4), (3 0 0), (1 0 10), (0 0 12), and (0 1 14), and TC(1 0 10) + TC(0 0 12) + TC(0 1 14) ≥ 7, and TC(1 0 10) ≥ 2, TC(0 0 12) ≥ 2, TC(0 1 14) ≥ 2.

[0008] In the above-mentioned coated cutting tool, the TiCN layer has a texture coefficient TC(hkl) measured by X-ray diffraction using CuKα radiation and θ-2θ scanning and defined according to the Harris formula, where I(hkl) is the measured intensity (integrated area) of the (h k l) reflection, I0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 42-1489; n is the number of reflections used in the calculation and the (h k l) reflections used are (0 1 1), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0), and (4 2 2) and where TC(3 1 1) + TC(4 2 2) ≥ 5.

[0009] TiCl4, CH3CN, H2, and N2 are used as reaction gases to deposit the medium-temperature TiCN layer. For the MT-TiCN-1 part closest to the substrate, the flow ratio of TiCl4 and CH3CN is controlled between 6.0 - 7.0, the deposition temperature is controlled between 850 - 880 °C, and the deposition time is 60 min - 180 min; for the middle MT-TiCN-2 part, the flow ratio of TiCl4 and CH3CN is controlled between 5.5 - 6.5, the deposition temperature is controlled between 880 - 900 °C, and the deposition time is 180 min - 300 min; for the MT-TiCN-3 part adjacent to the transition layer, the flow ratio of TiCl4 and CH3CN is controlled between 6.0 - 7.0, the deposition temperature is controlled between 850 - 880 °C, and the deposition time is 60 min - 180 min.

[0010]

[0011] In an embodiment of the present invention, the texture coefficients of the MT-TiCN crystal planes of the invention sample are shown in the table, where TC(31 1) + TC(4 2 2) = 5.45.

[0012] In the above-mentioned coated cutting tool, the transition layer has a face-centered cubic structure with a thickness of 1.0 μm - 2.0 μm, preferably 1.0 μm - 1.5 μm. The transition layer comprises three sub-layers, namely, an equiaxed HT-TiCN layer adjacent to MT-TiCN, a nano-sheet crystal HT-TiCN pre-nucleation layer, and an oxygen-containing TiCxNyOz layer, in that order.

[0013] In the above-mentioned coated cutting tool, the thickness of the α-Al2O3 layer is 3.0 μm - 10.0 μm, preferably 4.0 μm - 8 μm, and it is characterized in that TC(1 0 10) + TC(0 0 12) + TC(0 1 14) ≥ 7, preferably ≥ 8, more preferably ≥ 8.5, and TC(10 10) ≥ 2, TC(0 0 12) ≥ 2, TC(0 1 14) ≥ 2, and TC(0 0 12) ≥ TC(0 1 14) ≥ TC(1 0 10).

[0014] In the above-mentioned coated cutting tool, the thickness of the medium-temperature titanium carbonitride MT-TiCN layer is 5 μm - 12 μm, preferably 6 μm - 10 μm, more preferably 6 μm - 9 μm.

[0015] In the above-mentioned coated cutting tool, the medium-temperature titanium carbonitride MT-TiCN layer includes three parts: the upper, middle, and lower parts. The MT-TiCN-1 part closest to the substrate, the MT-TiCN-3 part adjacent to the transition layer, and the MT-TiCN-2 part in the middle. The thickness of the MT-TiCN-1 part is 1 - 3 μm, preferably 1 - 2 μm, and the average grain size of the transverse grains is 0.1 - 0.3 μm. The thickness of the MT-TiCN-2 part is 3 - 6 μm, preferably 4 - 5 μm, and the average grain size of the transverse grains is 0.2 - 0.5 μm. The thickness of the MT-TiCN-3 part is 1 - 3 μm, preferably 1 - 2 μm, and the average grain size of the transverse grains is 0.2 - 0.4 μm.

[0016] In the above-mentioned coated cutting tool, the cross-sectional grain morphology of the TiCxNyOz sub-layer contained in the transition layer is lenticular, and each grain is composed of at least 2 sub-grains with a grain boundary orientation angle of less than 10 degrees.

[0017] In the above-mentioned coated cutting tool, the composition of the TiCxNyOz transition layer has a gradient change in the atomic contents of C, N, and O, where x + y + z = 1. It is characterized in that at the position adjacent to the HT-TiCN layer, 0.9 < y / x < 1.1 and 0 < z < 0.005, and at a distance of 1 μm from the interface between the HT-TiCN layer and the TiCxNyOz transition layer, 1.1 < y / x < 1.5 and 0 < z < 0.1.

[0018] In the above-mentioned coated cutting tool, the substrate is cemented carbide, cermet, ceramic, high-speed steel or cBN.

[0019] In the above-mentioned coated cutting tool, the substrate is cemented carbide containing 3-14% by weight of cobalt and more than 50% by weight of tungsten carbide.

[0020] In the above-mentioned coated cutting tool, a medium-temperature TiCN layer with different grain size distribution characteristics is obtained by adjusting parameters such as the flow ratio of TiCl4 and CH3CN. The bonding strength between the transition layer and the medium-temperature TiCN layer is improved by setting a nanosheet crystal pre-nucleation layer between the medium-temperature TiCN layer and the transition layer. A sub-grain toughened transition layer with a specific composition change rule and an α-Al2O3 layer with a specific orientation are obtained by adjusting the change of the reaction gas flow rate in the transition layer.

[0021] Compared with the prior art, the present coated cutting tool has the following advantages:

[0022] 1. The α-Al2O3 layer with a combination of three preferred orientations of (1 0 10), (0 0 12) and (0 1 14) has better wear resistance and toughness, and can effectively inhibit early breakage such as micro-chipping of the coating on the cutting edge, thereby improving the tool durability.

[0023] 2. A new type of MT-TiCN, which is composed of three parts with different grain sizes, can significantly improve the wear resistance of the coating, especially the flank wear resistance and crater wear resistance on the rake face.

[0024] 3. By setting a nanosheet crystal pre-nucleation layer between the medium-temperature TiCN layer and the transition layer, the bonding strength between the transition layer and the medium-temperature TiCN layer is significantly improved, and interlayer spalling during the actual cutting process is effectively inhibited, thereby ensuring the stability of the tool service life.

[0025] 4. The face-centered cubic transition layer with a composition gradient change and grains composed of multiple sub-crystalline domains can effectively absorb the impact energy during cutting, provide good deformation ability, and ensure the impact resistance of the coating. Description of the Drawings

[0026] Figure 1 It is an optimized model of the transition layer structure for improving the bonding strength of the transition layer.

[0027] Figure 2 It is the morphology of the nanosheet crystal TiCN nucleation layer.

[0028] Figure 3 It is a typical scratch morphology diagram of Example 2 in the scratch bonding strength comparison table.

[0029] Figure 4It is the typical scratch morphology diagram of Comparative Example 2 in the scratch adhesion comparison table.

[0030] Figure 5 It is the adhesion comparison diagram by the indentation method in Example 6. Detailed implementation manners

[0031] The following are specific embodiments of the present invention and in conjunction with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0032] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 shown, the present coated cutting tool is made of a hard metal, cermet or ceramic substrate and a multi-layer wear-resistant coating. The multi-layer wear-resistant coating is applied to the substrate by means of a CVD method. The multi-layer wear-resistant coating has a total thickness of 5 to 40 μm. The multi-layer wear-resistant coating at least includes a medium-temperature titanium carbonitride MT-TiCN layer, an α-Al2O3 layer, and a transition layer deposited between the medium-temperature titanium carbonitride MT-TiCN layer and the α-Al2O3 layer;

[0033] wherein the α-Al2O3 has a texture coefficient TC(h k l) measured by X-ray diffraction using cuKa radiation and θ-2θ scanning and defined according to Harris formula;

[0034]

[0035] wherein I(hkl) is the measured intensity (integrated area) of the (h k l) reflection; I0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 10-0173; n is the number of reflections used in the calculation and the (h k l) reflections used are (0 1 2), (1 0 4), (110), (1 1 3), (1 1 6), (2 1 4), (3 00), (1010), (0 012), and (0 1 14), and TC(1 0 10)+TC(0 0 12)+TC(0 1 14)≥7, and TC(1 0 10)≥2, TC(00 12)≥2, TC(0 1 14)≥2.

[0036] In one embodiment of the present invention, the TiCN layer has a texture coefficient TC(hkl) measured by X-ray diffraction using CuKα radiation and θ-2θ scanning and defined according to the Harris formula, where I(hkl) is the measured intensity (integrated area) of the (hkl) reflection, I0(hkl) is the standard intensity of the standard powder diffraction data according to JCPDS card No. 42-1489; n is the number of reflections used in the calculation and the (h k l) reflections used are (0 1 1), (2 0 0), (2 2 0), (3 1 1), (3 3 1), (4 2 0) and (4 2 2) and where TC(3 1 1)+TC(4 2 2)≥5.

[0037] Medium-temperature titanium carbonitride MT-TiCN includes three parts: upper, middle and lower. By adjusting parameters such as the flow ratio of TiCl4 and CH3CN, medium-temperature TiCN layers with different grain size distribution characteristics are obtained. The MT-TiCN-1 part closest to the substrate, the MT-TiCN-3 part adjacent to the transition layer, and the middle MT-TiCN-2 part. The thickness of the MT-TiCN-1 part is 1-3 μm, preferably 1-2 μm, and the average lateral grain size is 0.1-0.3 μm. The thickness of the MT-TiCN-2 part is 3-6 μm, preferably 4-5 μm, and the average lateral grain size is 0.2-0.5 μm. The thickness of the MT-TiCN-3 part is 1-3 μm, preferably 1-2 μm, and the average lateral grain size is 0.2-0.4 μm.

[0038] TiCl4, CH3CN, H2, and N2 are used as reaction gases to deposit the medium-temperature TiCN layer. For the MT-TiCN-1 part closest to the substrate, the flow ratio of TiCl4 and CH3CN is controlled between 6.0-7.0, the deposition temperature is controlled between 850-880 °C, and the deposition time is 60 min - 180 min; for the middle MT-TiCN-2 part, the flow ratio of TiCl4 and CH3CN is controlled between 5.5-6.5, the deposition temperature is controlled between 880-900 °C, and the deposition time is 180 min - 300 min; for the MT-TiCN-3 part adjacent to the transition layer, the flow ratio of TiCl4 and CH3CN is controlled between 6.0-7.0, the deposition temperature is controlled between 850-880 °C, and the deposition time is 60 min - 180 min;

[0039]

[0040] In one embodiment of the present invention, the crystal plane texture coefficients of the invention sample MT-TiCN are shown in the table, where TC(31 1)+TC(4 2 2)=5.45.

[0041] The thickness is 1.0 μm - 2.0 μm, preferably 1.0 μm - 1.5 μm. The transition layer includes three sub-layers, which are in sequence an equiaxed HT-TiCN layer adjacent to MT-TiCN, a nano-sheet crystal HT-TiCN pre-nucleation layer, and an oxygen-containing TiCxNyOz layer. TiC x N y O z The cross-sectional grain morphology of the sub-layer is lens-shaped, and each grain is composed of at least 2 sub-grain crystals with a grain boundary orientation angle less than 10 degrees; the TiC x N y O z The composition of the sub-layer has a gradient change in the atomic contents of C, N, and O, where x + y + z = 1. It is characterized in that at the position adjacent to the HT-TiCN layer, 0.9 < y / x < 1.1 and 0 < z < 0.005, and at 1 μm from the interface between the HT-TiCN layer and TiC x N y O z 1.1 < y / x < 1.5 and 0 < z < 0.1.

[0042] As is well known, TiC x N y O z The transition layer can improve the bonding force between MT-TiCN and Al2O3. If TiC x N y O z The transition layer is directly deposited on the surface of MT-TiCN. On the one hand, due to the composition difference between the two, under the action of cutting heat during the cutting process, the O element in the transition layer diffuses to the MT-TiCN side, resulting in the phase transformation of MT-TiCN and thus generating pores at the interface; on the other hand, due to the differences in composition and crystal orientation, the bonding strength at the interface between MT-TiCN and the transition layer is not high. Therefore, the bonding interface between them is often the weak link of the entire coating, and the cracking and damage at the interface between the transition layer and MT-TiCN are important reasons for the coating failure. In the present invention, first, an equiaxed HT-TiCN sub-layer is set between the medium-temperature TiCN layer and the oxygen-containing TiC x N y O z sub-layer, which can effectively inhibit the diffusion of elements such as O between the two sides of the interface and thus inhibit the phase transformation. At the same time, the HT-TiCN sub-layer epitaxially grows on the surface of MT-TiCN and has good bonding force; then, a nano-sheet crystal pre-nucleation layer is set between the equiaxed HT-TiCN sub-layer and the oxygen-containing TiC x N y O z sub-layer, which can significantly improve the oxygen-containing TiC x N y O zThe bonding strength between the sub-layer and the equiaxed HT-TiCN sub-layer can effectively inhibit interlayer spalling during cutting, thus ensuring the stability of the tool service life. MT-TiCN, HT-TiCN layer, nucleation layer and TiC x N y O z layer and the schematic diagram are as Figure 1 shown. The morphology of the nano-sheet crystal pre-nucleation layer can be seen in Figure 2 .

[0043] The specific deposition operation of the transition layer is as follows:

[0044] Table 1 Deposition parameters of the transition layer

[0045]

[0046] Transition layer TiC x N y O z Detection method for the composition and crystal form of the sub-layer.

[0047] TiC x N y O z Cross-section metallography of the TiC

[0048] N x N y O z sub-layer: At a certain inclination angle, use a diamond grinding disc or sandpaper to remove and polish the alumina layer to obtain a cross-section metallography sample of the transition layer, and observe the grain morphology of the cross-section of the transition layer using an optical microscope (OM) or a scanning electron microscope (SEM). x N y O z Longitudinal-section metallography of the TiC x N y O z sub-layer: Cut the coating sample along the direction perpendicular to the substrate surface, and perform metallographic sample preparation on the cut surface to obtain a cross-section metallography sample in the coating growth direction. Use the EBSD method to analyze and obtain the data of the longitudinal-section grains and their sub-grain domains of the TiC

[0049] Before depositing alumina, it is first necessary to oxidize the surface of the transition layer to ensure correct nucleation of pure α-Al2O3. The oxidation treatment is divided into several steps:

[0050] 1. Purge with hydrogen or argon for 1 - 5 min;

[0051] 2. Purge the surface of the transition layer with AlCl3 (Al treatment) for 1 - 5 min;

[0052] 3. Oxidize the Al-coated surface with a mixed gas of H2, CO2, and CO for 1-2 minutes;

[0053] 4. Repeat the previous steps 1-3 for 2-5 times.

[0054] After completing the correct oxidation treatment, start the nucleation step and growth process of alumina.

[0041] In one embodiment of the present invention, the nucleation step and growth parameters of alumina are shown in Table 2;

[0055] Table 2 Alumina deposition parameters

[0056]

[0057] The α-Al2O3 has a texture coefficient TC(h k l) measured by X-ray diffraction using CuKα radiation and θ-2θ scanning and defined according to Harris' formula;

[0058]

[0059] Where I(hkl) is the measured intensity (integrated area) of the (h k l) reflection; I0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 10-0173; n is the number of reflections used in the calculation and the (h k l) reflections used are (0 1 2), (1 0 4), (1 1 0), (1 1 3), (1 1 6), (2 1 4), (3 0 0), (1 010), (0 0 12), and (0 1 14), and TC(1 0 10)+TC(0 0 12)+TC(0 1 14)≥7, preferably ≥8, more preferably ≥8.5, and TC(1 0 10)≥2, TC(0 0 12)≥2, TC(0 1 14)≥2.

[0060] Table 3 Texture coefficients of each crystal plane of alumina.

[0061]

[0062] In one embodiment of the present invention, the texture coefficients of the alumina crystal planes of the invention sample are shown in Table 3, where TC(10 10)+TC(0 0 12)+TC(0 1 14)=8.87, and TC(1 0 10)≥2, TC(0 0 12)≥2, TC(0 1 14)≥2.

[0063] The thickness of the α-Al2O3 layer is 3.0 μm - 10.0 μm, preferably 4.0 μm - 8 μm, characterized in that TC(1 0 10) + TC(0 0 12) + TC(0 1 14) ≥ 7, preferably ≥ 8, more preferably ≥ 8.5, and TC(1 0 10) ≥ 2, TC(0 0 12) ≥ 2, TC(0 1 14) ≥ 2, and TC(0 0 12) ≥ TC(0 1 14) ≥ TC(1 0 10).

[0064] The thickness of the medium-temperature titanium carbonitride MT-TiCN layer is 5 μm - 12 μm, preferably 6 μm - 10 μm, more preferably 6 μm - 9 μm.

[0065] The medium-temperature titanium carbonitride MT-TiCN layer includes three parts: the upper, middle, and lower parts. The MT-TiCN-1 part closest to the substrate, the MT-TiCN-3 part adjacent to the transition layer, and the MT-TiCN-2 part in the middle. The thickness of the MT-TiCN-1 part is 1 - 3 μm, preferably 1 - 2 μm, and the average grain size of the transverse grains is 0.1 - 0.3 μm. The thickness of the MT-TiCN-2 part is 3 - 6 μm, preferably 4 - 5 μm, and the average grain size of the transverse grains is 0.2 - 0.5 μm. The thickness of the MT-TiCN-3 part is 1 - 3 μm, preferably 1 - 2 μm, and the average grain size of the transverse grains is 0.2 - 0.4 μm.

[0066] The cross-sectional grain morphology of the TiCxNyOz sub-layer contained in the transition layer is lens-shaped, and each grain is composed of at least 2 sub-grains with a grain boundary orientation angle less than 10 degrees.

[0067] The composition of the TiCxNyOz transition layer has a gradient change in the contents of C, N, and O atoms, where x + y + z = 1. It is characterized in that at the position adjacent to the HT-TiCN layer, 0.9 < y / x < 1.1 and 0 < z < 0.005, and at a position 1 μm away from the interface between the HT-TiCN layer and the TiCxNyOz transition layer, 1.1 < y / x < 1.5 and 0 < z < 0.1.

[0068] The substrate is cemented carbide, cermet, ceramic, high-speed steel, or cBN.

[0069] The substrate is a cemented carbide containing 3 - 14 weight percent cobalt and more than 50 weight percent tungsten carbide.

[0070] By adjusting parameters such as the flow ratio of TiCl4 and CH3CN, medium-temperature TiCN layers with different grain size distribution characteristics are obtained. By setting a nano-sheet crystal pre-nucleation layer between the medium-temperature TiCN layer and the transition layer, the bonding force between the transition layer and the medium-temperature TiCN layer is improved. By adjusting the change in the flow rate of the reaction gas in the transition layer, a sub-grain toughened transition layer with a specific composition change rule and an α-Al2O3 layer with a specific orientation are obtained.

[0071] The cutting tools with the coatings described herein can undergo post-treatment such as any combination of sandblasting, brushing, or shot peening. The post-treatment of sandblasting can be wet sandblasting or dry sandblasting, for example, using alumina particles.

[0072] Other objects and features of the present invention will become clear by considering the following definitions and embodiments in conjunction with the accompanying drawings.

[0073] In the manufacturing method according to this embodiment, in addition to the above steps, additional steps can be appropriately carried out within the scope of not impairing the effects of this embodiment. As the above additional steps, for example, there can be mentioned: the step of forming a surface layer on the above alumina layer, and the step of performing sandblasting, shot peening, or polishing treatment on the coating. After the alumina layer, a color layer of one or a combination of several of TiN, TiC, and TiCN can be deposited as the outermost layer according to the prior art. As a method of forming the surface layer, there is no particular limitation, and for example, a method of forming by CVD method or the like can be mentioned.

[0074] Example 1:

[0075] A cemented carbide with a Co content of 7.5 wt.%, a (Ti,Ta,Nb)CN cubic solid solution content of 3.0 wt.%, and the rest being WC is used as the substrate of the coated blade, and the geometric model is a turning tool for steel WNMG080408. After the blade is subjected to edge passivation, surface sandblasting treatment, and cleaning, CVD coating operation is carried out. First, about 0.5 μm thick TiN is deposited at 950 °C as the connection layer between the substrate and MT-TiCN by the prior art. Then, the MT-TiCN layer, the transition layer, and the alumina layer are deposited in sequence according to the following table. The surface of the coated blade is subjected to wet sandblasting with alumina to release the internal stress in the coating, improve the surface finish of the coating, and reduce the surface roughness;

[0076]

[0077]

[0078]

[0079]

[0080] The transition layer contains oxygen-containing TiC x N y O z The position of the sub-layer adjacent to the HT-TiCN layer is y / x = 1.05, z = 0.004, and the distance from the HT-TiCN layer and TiC x N y O zAt 1 μm from the interface of the transition layer, y / x = 1.34 and z = 0.073.

[0081] The thickness of alumina is 5.4 μm, and TC(1 0 10) + TC(0 0 12) + TC(0 1 14) = 8.92.

[0082] Comparative Example 1:

[0083] A cemented carbide with 7.5 wt.% Co, 3.0 wt.% (Ti,Ta,Nb)CN cubic solid solution, and the rest WC is used as the substrate of the coated blade. The geometric model is a turning tool for steel WNMG080408. After the blade is subjected to edge passivation, surface sandblasting, and cleaning, CVD coating operation is carried out. First, TiN, MT-TiCN layer, transition layer, and alumina layer are deposited in sequence by the existing technology. The thickness of MT-TiCN is 8.0 μm, the strongest orientation crystal planes of MT-TiCN are (111) and (422), the thickness of the transition layer is 0.8 μm, the thickness of alumina is 5.3 μm, the preferred orientation of alumina is (012), TC(012) = 5.3, and TC(1 0 10) + TC(0 0 12) + TC(0 1 14) = 2.1. The alumina wet sandblasting operation on the surface of the coated blade is the same as that in Example 1.

[0084] Example 2:

[0085] A cemented carbide with 6.0 wt.% Co and the rest WC is used as the substrate of the coated blade. The geometric model is a turning tool for cast iron WNMG080408. After the blade is subjected to edge passivation, surface sandblasting, and cleaning, CVD coating operation is carried out. First, about 0.5 μm thick TiN is deposited at 950 °C by the existing technology as the connection layer between the substrate and MT-TiCN. Then, the MT-TiCN layer, transition layer, and alumina layer are deposited in sequence according to the following table. After the alumina coating, a 1 μm thick TiN layer is deposited as the outermost layer of the blade by the existing CVD technology. The surface of the coated blade is subjected to alumina wet sandblasting until the surface TiN is basically removed, and the rake face and flank face of the blade become black, while the alumina has no obvious damage and peeling;

[0086]

[0087]

[0088]

[0089] The transition layer contains oxygen-containing TiC x N y O zThe position of the sub-layer adjacent to the HT-TiCN layer is y / x = 1.07 and z = 0.005, and the distance from the HT-TiCN layer and TiC x N y O z At the interface of the transition layer at 1 μm, y / x = 1.24 and z = 0.067.

[0090] The thickness of alumina is 6.0 μm, and TC(1 0 10) + TC(0 0 12) + TC(0 1 14) = 8.93.

[0091] Comparative Example 2:

[0092] The same turning tool as in Example 2 was used. After the cutting edge was passivated, the surface was sandblasted and cleaned, and then the CVD coating operation was carried out. First, TiN, MT-TiCN layer, transition layer, alumina layer and the outermost TiN layer were deposited in sequence by the prior art. The thickness of MT-TiCN is 8.3 μm, the strongest orientation crystal planes of MT-TiCN are (111) and (422), the thickness of the transition layer is 0.75 μm, the thickness of alumina is 6.1 μm, the preferred orientation of alumina is (012), TC(012) = 4.8, and TC(1 0 10) + TC(0 0 12) + TC(0 1 14) = 2.6. The wet sandblasting operation of alumina on the surface of the coated tool was the same as in Example 2.

[0093] Example 3:

[0094] In the dry turning test, a 45# steel round bar with a cutting diameter of 250 mm was cut to test the wear resistance of the sample.

[0095] The cutting parameters are as follows:

[0096] Cutting speed Vc: 350 m / minute;

[0097] Feed fn: 0.2 mm / revolution;

[0098] Cutting depth ap: 2 mm;

[0099] The stop criterion is defined as when the flank wear (Vb) ≥ 0.3 mm or the cutting edge is chipped. Each cutting edge was inspected every 5 minutes of cutting, and the flank wear value of the main cutting edge was measured. The following table shows the cutting time at Vb = 0.3 mm for 3 parallel tests.

[0100]

[0101] Example 4:

[0102] In the dry turning test, a HT300 cast iron round bar material with a cutting diameter of 250 mm was cut to test the wear resistance of the sample. The cutting parameters are as follows:

[0103] Cutting speed Vc: 450 m / min;

[0104] Feed rate fn: 0.2 mm / rev;

[0105] Cutting depth ap: 2 mm;

[0106] The stopping criterion is defined as when the flank wear (Vb) ≥ 0.3 mm or the cutting edge is chipped. Check each cutting tip after every 5 minutes of cutting and measure the flank wear value of the main cutting edge. The following table shows the cutting time at Vb = 0.3 mm for 3 parallel tests;

[0107]

[0108] Example 5:

[0109] In the dry turning test, a 45# steel round bar material with a cutting diameter of 250 mm and 4 equally spaced longitudinal grooves along the length direction is cut to test the impact resistance of the sample. The cutting parameters are as follows:

[0110] Parameter 1:

[0111] Cutting speed Vc: 220 m / min;

[0112] Feed rate fn: 0.2 mm / rev;

[0113] Cutting depth ap: 1.5 mm;

[0114] Each sample is tested on 10 cutting tips. Each tested cutting tip is cut constantly for 5 minutes, then the integrity of the cutting tip and the cutting edge is observed under a microscope, and the number of cutting tips with chipping or breakage is recorded.

[0115] Parameter 2:

[0116] Cutting speed Vc: 220 m / min;

[0117] Feed rate fn: 0.3 mm / rev;

[0118] Cutting depth ap: 2.0 mm;

[0119] Each sample is tested on 10 cutting tips. Each tested cutting tip is cut constantly for 5 minutes, then the integrity of the cutting tip and the cutting edge is observed under a microscope, and the number of cutting tips with chipping or breakage is recorded;

[0120]

[0121] Example 6:

[0122] The indentation method (Rockwell hardness tester, maximum loading pressure 100 Kg) and the scratch method (scratch tester, maximum loading load 120 N) were used to test the adhesion of the CVD coating, and the results are compared as follows:

[0123] Comparison of scratch adhesion:

[0124] Sample 1 Sample 2 Sample 3 Sample 4 Example 1 120N 120N 120N 120N Control Example 1 105N 95N 105N 100N Example 2 120N 120N 120N 120N Control Example 2 95N 101N 99N 102N

[0125] From the above cutting experiment data, it can be seen that the coated cemented carbide blade of the present invention exhibits better wear resistance than the existing process when continuously machining steel parts and cast iron, and at the same time shows more stable impact resistance during interrupted turning of 45# steel. From the comparison experiment results of testing the coating adhesion by the indentation method and the scratch method, it can be known that the coating of the present invention has better film / substrate interface adhesion and better interlayer interface adhesion inside the film, which is one of the main reasons for the improvement of cutting performance.

[0126] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A coated cutting tool, characterized in that, It is made of a hard metal, a substrate, and a multi-layer wear-resistant coating. The substrate is a cemented carbide containing 3-14 weight percent cobalt and more than 50 weight percent tungsten carbide. The multi-layer wear-resistant coating is applied to the substrate by means of a CVD method. The multi-layer wear-resistant coating has a total thickness of 5 to 40 μm. The multi-layer wear-resistant coating at least includes a medium-temperature titanium carbonitride MT-TiCN layer, an α-Al2O3 layer, and a transition layer deposited between the medium-temperature titanium carbonitride MT-TiCN layer and the α-Al2O3 layer; wherein the α-Al2O3 has a texture coefficient TC(h k l) measured by X-ray diffraction using cuKa radiation and θ-2θ scanning and defined according to the Harris formula; where I(hkl) is the measured intensity of the (h k l) reflection; I0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 10-0173; n is the number of reflections used in the calculation and the (h k l) reflections used are (012), (1 0 4), (11 0), (1 1 3), (1 1 6), (2 1 4), (3 00), (1010), (0 0 12), and (0 1 14), and TC(1 0 10)+TC(0 0 12)+TC(0 1 14)≥7, and TC(1 0 10)≥2, TC(0 0 12)≥2, TC(01 14)≥2.

2. A coated cutting tool according to claim 1, wherein the TiCN layer has a texture coefficient TC(hkl) measured by X-ray diffraction using cuKa radiation and θ-2θ scanning and defined according to the Harris formula, where I(hkl) is the measured intensity of the (hkl) reflection, I 0(hkl) is the standard intensity according to the standard powder diffraction data of JCPDS card No. 42-1489; n is the number of reflections used in the calculation and the (h kl) reflections used are (0 1 1), (2 0 0), (2 20), (3 1 1), (3 3 1), (4 2 0), and (4 2 2) and wherein TC(3 1 1)+TC(4 2 2)≥5.

3. A coated cutting tool according to claim 1, wherein the transition layer has a face-centered cubic structure with a thickness of 1.0 μm - 2.0 μm, and the transition layer comprises three sub-layers, namely an equiaxed HT-TiCN layer adjacent to MT-TiCN, a nano-sheet crystal HT-TiCN pre-nucleation layer, and an oxygen-containing TiC x N y O z layer.

4. A coated cutting tool according to claim 1, wherein the α-Al2O3 layer has a thickness of 3.0 μm - 10.0 μm, TC(1010)+TC(0 0 12)+TC(0 1 14)≥7, and TC(1 0 10)≥2, TC(0 0 12)≥2, TC(01 14)≥2, and TC(0 0 12)≥TC(0 1 14)≥TC(1 0 10).

5. A coated cutting tool according to claim 2, wherein the medium-temperature titanium carbonitride MT-TiCN layer has a thickness of 5 μm - 12 μm.

6. A coated cutting tool according to claim 2, wherein the medium-temperature titanium carbonitride MT-TiCN layer comprises three parts: an upper part, a middle part, and a lower part. The MT-TiCN-1 part closest to the substrate, the MT-TiCN-3 part adjacent to the transition layer, and the MT-TiCN-2 part in the middle. The MT-TiCN-1 part has a thickness of 1-3 μm and an average transverse grain size of 0.1-0.3 μm. The MT-TiCN-2 part has a thickness of 3-6 μm and an average transverse grain size of 0.2-0.5 μm. The MT-TiCN-3 part has a thickness of 1-3 μm and an average transverse grain size of 0.2-0.4 μm.

7. A coated cutting tool according to claim 3, wherein the TiC contained in the transition layer x N y O z sub-layer has a lens-shaped cross-sectional grain morphology, and each grain is composed of at least 2 sub-grains with a grain boundary orientation angle of less than 10 degrees.

8. A coated cutting tool according to claim 3, wherein the TiC x N y O z transition layer composition has a gradient change in the atomic contents of C, N, and O, where x + y + z = 1, and is characterized in that At a position adjacent to the HT-TiCN layer, 0.9 < y / x < 1.1 and 0 < z < 0.005, the distance from the HT-TiCN layer and TiC x N y O z At 1 μm from the interface of the transition layer, 1.1 < y / x < 1.5 and 0 < z < 0.1.

Images