Surface composite coated cutting tool and method of making and use thereof

Abstract

This invention discloses a surface composite coating cutting tool, its preparation method, and its application. The cutting tool includes a tool substrate and a surface composite coating disposed on the tool substrate. The surface composite coating contains at least one layer of α-Al₂O₃ coating prepared by chemical vapor deposition. The α-Al₂O₃ coating has a preferred texture orientation relative to the {018} and {1010} planes of the crystal, and the texture coefficient satisfies the following characteristics: 6.0 ≤ TC(018) + TC(1010) < 12.0, and 3.0 < TC(018) < 10.0, 2.0 ≤ TC(1010) < 9.0. Each layer of the surface composite coating of this cutting tool is deposited by CVD. The surface composite coating cutting tool of this invention has excellent wear resistance and anti-chipping properties, and exhibits excellent comprehensive performance in intermittent machining or high thermal shock loads of materials such as cast iron, steel, and stainless steel.

Description

Technical Field

[0001] This invention belongs to the field of coated cutting tool technology, specifically relating to a surface composite coated cutting tool, its preparation method, and its application. Background Technology

[0002] With the deepening implementation of the concepts of efficient and green manufacturing, high-efficiency cutting has gradually become the mainstream trend in modern machining. The continuous innovation and iterative upgrading of tool coating technology plays a key supporting role in improving tool cutting performance, extending service life, and promoting the advancement of machining technology. Coated tools have therefore become the core development symbol of modern high-performance cutting tools.

[0003] Alumina (Al2O3) coatings, with their excellent chemical stability, good high-temperature oxidation resistance, and outstanding thermal barrier protection, are effectively adapted to the harsh service environments of high-speed cutting, such as high temperatures and friction, making them a highly valuable coating material in the field of high-speed cutting tools. When preparing alumina coatings using chemical vapor deposition (CVD), α-Al2O3 is widely recognized as the preferred phase for wear-resistant coatings for cutting tools due to its high thermodynamic stability, structural stability, and excellent wear resistance. CVD-prepared α-Al2O3 coatings have been widely used in various cutting tools.

[0004] Recent studies have shown that the preferred orientation of coating grains has a significant regulatory effect on its mechanical properties, wear resistance and service behavior. Coatings with specific texture orientations often exhibit superior performance characteristics under specific working conditions. Therefore, texture control technology has become an important research direction in the field of tool coatings.

[0005] Chinese patent document CN105714268B discloses a strongly textured oriented alumina coating with TC(0012)≥7.2. This type of coating has certain advantages in wear resistance and can be used in processing applications with stringent wear resistance requirements. However, the performance of high (0012) textured oriented α-Al2O3 coatings is insufficient under intermittent cutting conditions of steel, cast iron, and stainless steel. Due to the preferential growth of grains along the (0012) crystal plane, the coating exhibits significant anisotropy, resulting in weak fracture toughness and impact resistance. In interrupted turning and milling processes involving cyclic impact loads, microcracks easily initiate and rapidly propagate at the cutting edge, leading to coating damage and even localized peeling. When machining tough materials like stainless steel, the high cutting temperatures and intense thermal cycling highlight the insufficient thermal shock resistance of such coatings, easily causing thermal fatigue cracks and accelerating coating failure. In interrupted cutting of brittle materials like cast iron, the concentrated impact loads make the coating even more prone to premature failure due to excessive brittleness. Furthermore, on factory production lines, a single tool tip can typically machine multiple parts. While machining a single part can be done with a single tool tip, either intermittently or continuously, the tool tip's entire cutting life is intermittent. During process changes or part replacements, the tool tip temperature drops sharply. Therefore, there are rapid thermal changes throughout the tool tip's cutting life, especially under dry cutting and milling conditions where the tool tip experiences even stronger thermal shocks. Therefore, how to significantly improve the toughness, thermal shock resistance and cutting stability of high-performance alumina coatings in intermittent machining of steel, cast iron and stainless steel while maintaining high wear resistance has become a key technical problem that needs to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a surface composite coating cutting tool with excellent comprehensive performance under interrupted machining or high thermal shock load, as well as its preparation method and application.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0008] A surface composite coating cutting tool includes a tool substrate and a surface composite coating disposed on the tool substrate. The surface composite coating contains at least one layer of α-Al2O3 coating prepared by chemical vapor deposition. The α-Al2O3 coating has a preferred texture orientation relative to the {018} and {1010} planes of the crystal, and the texture coefficient satisfies the following characteristics: 6.0≤TC(018)+TC(1010)<12.0, and 3.0<TC(018)<10.0, 2.0≤TC(1010)<9.0.

[0009] Preferably, in the above-mentioned surface composite coating cutting tool, the surface composite coating further includes a lower wear-resistant layer, which is disposed between the α-Al2O3 coating and the tool substrate. The lower wear-resistant layer is composed of a Ti compound and has an average thickness of 1.0 μm to 18 μm.

[0010] Preferably, in the above-mentioned surface composite coating cutting tool, the surface composite coating further includes a central bonding layer, which is disposed between the α-Al2O3 coating and the lower wear-resistant layer. The central bonding layer comprises one or more TA layers and one oxide OA layer from bottom to top. The TA layer comprises a Ti compound layer and a TiAl compound layer from bottom to top. The total thickness of the TA layer is 0.1 μm to 1.5 μm, and the average thickness of the central bonding layer is 0.1 μm to 2.0 μm.

[0011] Preferably, in the above-mentioned surface composite coating cutting tool, the surface composite coating further includes a bottom adhesive layer, which is disposed between the lower wear-resistant layer and the tool substrate. The bottom adhesive layer is composed of a Ti compound and has an average thickness of 0.1 μm to 3 μm.

[0012] Preferably, in the above-mentioned surface composite coating cutting tool, the surface composite coating further includes a surface layer disposed on the α-Al2O3 coating, the surface layer being composed of a Ti compound, and the average thickness of the surface layer being 0.1 μm to 3.0 μm.

[0013] Preferably, in the above-mentioned surface composite coating cutting tool, the α-Al2O3 coating has a thickness of 1.0 μm to 18.0 μm, and the microstructure of the α-Al2O3 coating is a fibrous columnar structure. The average width of the columnar grains at 50% of the thickness along the growth direction of the α-Al2O3 coating on a cross section perpendicular to the α-Al2O3 coating is set as d, and the thickness of the α-Al2O3 coating is set as h, where the ratio of h to d is h / d≥12.

[0014] Preferably, in the above-mentioned surface composite coating cutting tool, the texture factor of the surface composite coating is represented by TC(hkl), which is defined as follows:

[0015] in, I( hkl )=( hkl The intensity of the reflected light. I 0( hkl=Based on the standard powder diffraction data of the applied JCPDF card No. 10-0173 ( hkl The standard intensity of reflection, n is the number of reflections used in the calculation, n=12. ( hkl ) i The (used) hkl ) i The reflective crystal planes are (012), (104), (110), (113), (116), (214), (300), (018), (1010), (0210), (0012) and (2110).

[0016] Preferably, the total thickness of the surface composite coating on the cutting tool described above is 2μm to 35μm.

[0017] As a general technical concept, the present invention also provides a method for preparing the above-mentioned surface composite coating cutting tool, comprising the following steps: A surface composite coating is deposited on the tool substrate. The surface composite coating contains at least one layer of α-Al₂O₃ coating prepared by chemical vapor deposition. The deposition conditions for the α-Al₂O₃ coating are: deposition temperature 980℃~1010℃, deposition pressure 4kPa~20kPa, initial introduction of 1.0vol%~6.0vol% AlCl₃ gas, 0.5vol%~3.0vol% CO₂ gas, 0.8vol%~6.0vol% CO gas, and the balance H₂ gas, and deposition time 30min~90min. The deposition temperature and / or pressure can be adjusted (deposition temperature 980℃~1010℃, deposition pressure 4kPa~20kPa). Then, 3.0 vol%~10.0 vol% AlCl3 gas, 0.5 vol%~5.0 vol% CO2 gas, 1.5 vol%~10.0 vol% CO gas, 0.2 vol%~1.0 vol% H2S gas, 0.3 vol%~2.5 vol% HCl gas, and the balance H2 gas are introduced. The volume fraction V of CO2 gas in the introduced deposition gas is... CO2 Volume fraction V of AlCl3 gas AlCl3 The ratio V CO2 / V AlCl3 The volume fraction V of H2S gas is 0.1–0.7. H2S V is the ratio of the volume fraction of oxygen-containing gas composed of CO2 and CO to the sum of their volume fractions. H2S / (V CO2 +V CO The concentration of 0.03 to 0.15 and the deposition time are 30 min to 1000 min.

[0018] Preferably, in the above-mentioned method for preparing a surface composite coating cutting tool, the surface composite coating further comprises a lower wear-resistant layer and a middle bonding layer. The lower wear-resistant layer is disposed between the α-Al2O3 coating and the tool substrate, and the lower wear-resistant layer is deposited using a CVD process. The middle bonding layer is disposed between the α-Al2O3 coating and the lower wear-resistant layer, and the middle bonding layer is deposited using a CVD process. The deposition process of the middle bonding layer is carried out in a coating furnace with two air inlets. The Ti compound layer for TA deposition: deposition temperature 930℃~1010℃, deposition pressure 0.8kPa~3kPa, deposition time 30min~70min. Two mixed gases are introduced into the coating furnace. The first mixed gas VT1 consists of 1.5vol%~9.0vol% TiCl4 gas, 3.0vol%~18.0vol% N2 gas, 0.5vol%~3.0vol% CH4 gas, and the balance H2 gas. The second mixed gas VT2 consists of 0.7vol%~3.0vol% NH3 gas and the balance H2 gas. The volume ratio of the first mixed gas VT1 to the second mixed gas VT2 is 1.5~6.0, and the volume fraction of N2 gas is V. N2 Volume fraction V of NH3 gas NH3 Ratio V N2 / V NH3 The volume fraction V of CH4 gas is 18–70. CH4 The ratio V to the total volume fraction of nitrogen-containing gas CH4 / (V N2 +V NH3 The volume fraction V of TiCl4 gas is 0.10–0.50. TiCl4 Volume fraction V of NH3 gas NH3 The ratio V TiCl4 / V NH3 The value ranges from 5.0 to 30. The TiAl compound layer for TA deposition: deposition temperature 950℃~1010℃, deposition pressure 1.0kPa~4.0kPa, deposition time 10min~70min. Two mixed gases are introduced into the coating furnace. The first mixed gas VA1 consists of 1.5vol%~9.0vol% TiCl4 gas, 1.0vol%~6.0vol% AlCl3 gas, 3.0vol%~5.0vol% CO gas, 7.0vol%~18.0vol% N2 gas, and the balance H2. The second mixed gas VA2 consists of 0.8vol%~3.0vol% NH3 gas and the balance H2 gas. The volume ratio of the first mixed gas VA1 to the second mixed gas VA2 is 1.5~6.0, and the volume fraction of N2 is V... N2 Volume fraction V of NH3 NH3 The ratio V N2 / V NH3 The volume fraction V of TiCl4 gas is 10–50. TiCl4 Volume fraction V of NH3 gas NH3 The ratio V TiCl4 / V NH3 The value ranges from 2.5 to 20.0. Deposition of oxide OA layer: Deposition temperature 950℃~1010℃, deposition pressure 2kPa~6kPa. A two-gas alternating deposition method is used. The first gas mixture VO1 consists of 3.0 vol%~12.0 vol% TiCl4 gas and the balance H2, while the second gas mixture VO2 consists of 1.8 vol%~6.5 vol% AlCl3 gas and the balance H2. While one gas stream enters the coating furnace for CVD deposition, the other gas stream does not enter the furnace but bypasses it and exits through the exhaust pipe. The single-phase VO1 gas mixture... The initial deposition time is 1 min to 3 min, and the single deposition time of the second mixed gas VO2 is 2 min to 5 min. Deposition is performed in an alternating pattern of VO1, VO2, VO1, VO2, with each VO1 and VO2 deposition constituting one group, repeated 3 to 10 times. The deposition temperature and / or deposition pressure can be adjusted (deposition temperature 950℃ to 1010℃, deposition pressure 2 kPa to 6 kPa). Then, 2.0 vol% to 5.0 vol% CO2 gas, 4.0 vol% to 12.0 vol% CO gas, and the balance H2 are introduced. The volume fraction of CO gas V... CO Volume fraction of CO2 gas V CO2 The ratio V CO / V CO2 The value is 1.0 to 3.0, and the deposition time is 3 min to 15 min.

[0019] In the above-described method for preparing surface composite coating cutting tools, preferably, the surface composite coating further includes a bottom adhesive layer, which is deposited using a CVD process.

[0020] In the above-described method for preparing surface composite coating cutting tools, preferably, the surface composite coating further comprises a surface layer, which is deposited using a CVD process.

[0021] As a general technical concept, the present invention also provides an application of the above-described surface composite coating cutting tool or the surface composite coating cutting tool prepared by the above-described preparation method in the fields of steel, cast iron and stainless steel.

[0022] The surface layer of this invention can be used simultaneously with the α-Al2O3 coating, the middle adhesive layer, the lower wear-resistant layer, and the bottom adhesive layer to achieve superior performance. Furthermore, the surface layer of this invention can also serve as a surface coloring layer to obtain better appearance and usability.

[0023] Surprisingly, a composite coated cutting tool of the present invention comprises a substrate made of a superhard material such as cemented carbide, cermet, ceramic, steel, or cubic boron nitride, and a multilayer wear-resistant coating coated thereon, having a total thickness of 2 μm to 35 μm, wherein at least one layer is an α-Al₂O₃ coating prepared by chemical vapor deposition (CVD), wherein the texture factor of the α-Al₂O₃ coating is 6.0 ≤ TC(0¹⁸) + TC(10¹⁰) < 12.0, and 3.0 < TC(0¹⁸) < 10.0, and 2.0 ≤ TC(10¹⁰) < 9.0. The cutting tool of the present invention exhibits excellent wear resistance and anti-chipping properties, and demonstrates superior performance in discontinuous, high-thermal-shock machining conditions of materials such as steel, cast iron, and stainless steel.

[0024] Compared with the prior art, the advantages of the present invention are as follows: 1. The core innovation of the surface composite coating cutting tool of this invention lies in solving the service shortcomings of existing high (0012) texture orientation α-Al2O3 coatings. Through the synergistic effect of precise control of texture orientation, optimization of grain structure and fine composite design of central bonding layer, high-performance deposition of α-Al2O3 coating on the surface of cutting tool is achieved. Finally, an α-Al2O3 coating with ultra-fine columnar crystal structure, synergistically optimized crystal growth orientation of (018) and (1010) and satisfying the texture coefficient range of 6.0≤(TC(018)+TC(1010))<12.0 is obtained. From the crystal growth mechanism level, the core technical problem of existing high (0012) texture α-Al2O3 coatings being weak in fracture toughness and impact resistance due to the preferential growth of grains along the (0012) crystal plane and significant anisotropy is solved.

[0025] The central adhesive layer of this invention employs a complex composite structure design, which is the key core support for achieving the aforementioned specific texture coefficient and overcoming the shortcomings of existing coatings. On the one hand, the adhesive layer effectively reduces the interfacial stress between the coating and the tool substrate, and between the α-Al2O3 coating and the adhesive layer through multi-layer structure and composition control, avoiding cracks caused by insufficient interfacial bonding during coating deposition. This provides a stable interfacial environment for the growth of ultra-fine columnar crystals in the α-Al2O3 coating, fundamentally improving the coating's basic impact resistance performance. On the other hand, the grain boundary modification design of the adhesive layer can directionally guide the α-Al2O3 coating crystals to abandon the (0012) single preferential growth mode and turn to the (018) and (1010) crystal planes for synergistic preferential growth. By precisely controlling the grain size and grain boundary energy of the adhesive layer, the texture coefficient is stably locked in the optimal range of 6.0≤(TC(018)+TC(1010))<12.0. The texture coefficient range has been verified by a large number of tests. It can not only retain the excellent high-temperature hardness and wear resistance of α-Al2O3 coating, but also effectively weaken the anisotropy of the coating, greatly improve the fracture toughness and impact resistance, and achieve a synergistic balance between "hardness and toughness". This is a key breakthrough that has not been achieved in the existing technology. The existing technology mostly uses a single (0012) texture control, which cannot take into account both impact resistance and wear resistance, and is prone to failure problems such as coating damage and peeling.

[0026] 2. The surface composite coating cutting tool of the present invention, through the synergistic design of the above-mentioned α-Al2O3 coating and the central bonding layer, achieves a leapfrog improvement in comprehensive service performance, addressing the performance defects of existing high (0012) textured coatings under intermittent cutting conditions. Its excellent wear resistance, anti-chipping performance, and thermal shock resistance have been verified by specific working conditions and supported by data, specifically solving the pain points of existing technologies: In the intermittent turning and milling of steel, cast iron, and stainless steel, the initiation and propagation of microcracks on the cutting edge are effectively suppressed, completely solving the problems of easy chipping and local peeling of existing coatings; In the high cutting temperature and severe thermal cycling scenarios of machining tough materials such as stainless steel, the thermal shock resistance and thermal fatigue resistance of the coating are significantly improved, avoiding the formation of thermal fatigue cracks and the phenomenon of accelerated coating failure; In the intermittent cutting of brittle materials such as cast iron, the disadvantage of excessive brittleness of the coating is effectively improved, and the problem of early damage is eliminated. Specifically, the quantitative results are as follows: In high-speed and high-efficiency machining scenarios with steel cutting speed ≥300m / min and cast iron cutting speed ≥500m / min, compared with existing high (0012)textured α-Al2O3 coated tools, the wear of the tool of the present invention is reduced by more than 40%, and the tool life is extended by more than 60%; under strong thermal shock conditions with temperature fluctuation range (such as intermittent cutting and alternating cooling media), the coating does not peel off or crack, and the machining efficiency and machining accuracy are stably guaranteed.

[0027] Furthermore, the core value of this invention lies in its ability to completely overcome the technical dilemma of existing high (0012) texture α-Al2O3 coatings, which cannot simultaneously achieve wear resistance, chipping resistance, and thermal shock resistance, through precise control of the texture coefficient and complex collaborative design of the bonding layer. It is precisely adapted to the harsh working conditions of intermittent cutting of steel, cast iron, and stainless steel, and can meet the processing requirements of aerospace, high-end equipment manufacturing and other fields with extremely high requirements for cutting accuracy and tool life. It provides key technical support for the domestic substitution of high-end cutting tools and has significant technological innovation value, engineering application value and industrial promotion prospects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the surface composite coating cutting tool CT01 in Embodiment 1 of the present invention.

[0029] Figure 2 The XRD diffraction pattern of the surface composite coating cutting tool CT01 in Embodiment 1 of the present invention is shown.

[0030] Legend: 1. Tool substrate; 2. Surface composite coating; 3. Bottom bonding layer; 4. Lower wear-resistant layer; 5. Middle bonding layer; 51. TA layer; 52. OA layer; 511. Ti compound layer of TA layer; 512. TiAl compound layer of TA layer; 6. α-Al2O3 coating; 7. Surface layer. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0032] Example 1 A surface composite coating cutting tool of the present invention, such as Figure 1 As shown, the tool substrate 1 and a surface composite coating 2 disposed on the tool substrate 1 are included. The surface composite coating 2 has a total thickness of 2 μm to 35 μm. The surface composite coating 2 contains at least one layer of α-Al2O3 coating 6 prepared by chemical vapor deposition. The α-Al2O3 coating 6 has a preferred texture orientation relative to the {018} and {1010} planes of the crystal. The texture coefficient of the α-Al2O3 coating 6 satisfies the following characteristics: 6.0≤TC(018)+TC(1010)<12.0, and 3.0<TC(018)<10.0, 2.0≤TC(1010)<9.0.

[0033] TC(hkl) is defined as follows:

[0034] in, I(hkl) = (hkl) is the measured intensity of the reflected light. I0(hkl) = Standard intensity of reflection based on the standard powder diffraction data (hkl) of the applied JCPDF card No. 10-0173. n = the number of reflections used in the calculation (here: n = 12), (hkl) i The (hkl) used i The reflective crystal planes are: (012), (104), (110), (113), (116), (214), (300), (018), (1010), (0210), (0012) and (2110).

[0035] In this embodiment, preferably, the texture coefficient TC(018)+TC(1010)+TC(0210)≥7.0 of the α-Al2O3 coating 6. More preferably, the texture coefficient TC(018)+TC(1010)+TC(0210)+TC(0012)≥8.0 of the α-Al2O3 coating 6.

[0036] In this embodiment, the α-Al2O3 coating 6 has a thickness of 1.0 μm to 18.0 μm, and the microstructure of the α-Al2O3 coating 6 is a fibrous columnar structure. The average width of the columnar crystal grains at 50% of the thickness along the growth direction of the α-Al2O3 coating on a cross section perpendicular to the coating surface is set as d, and the thickness of α-Al2O3 is set as h. The ratio of h to d is h / d≥12.

[0037] In this embodiment, the surface composite coating 2 also includes a lower wear-resistant layer 4, which is disposed between the α-Al2O3 coating 6 and the tool substrate 1. The lower wear-resistant layer 4 is composed of Ti compound, and the average thickness of the lower wear-resistant layer 4 is 1.0 μm to 18 μm.

[0038] In this embodiment, the surface composite coating 2 further includes a middle adhesive layer 5, which is disposed between the α-Al2O3 coating 6 and the lower wear-resistant layer 4. The middle adhesive layer 5 includes one or more TA layers 51 and one oxide OA layer 52 from bottom to top. The TA layer 51 has a Ti compound layer 511 and a TiAl compound layer 512 from bottom to top. The total thickness of the TA layer 51 is 0.1μm to 1.5μm, and the average thickness of the middle adhesive layer 5 is 0.1μm to 1.8μm.

[0039] In this embodiment, the surface composite coating 2 also includes a bottom adhesive layer 3, which is disposed between the lower wear-resistant layer 4 and the tool substrate 1. The bottom adhesive layer 3 is composed of a Ti compound and has an average thickness of 0.1 μm to 3 μm.

[0040] In this embodiment, the surface composite coating 2 further includes a surface layer 7, which is disposed on the α-Al2O3 coating 6. The surface layer 7 is composed of a Ti compound and has an average thickness of 0.1 μm to 3.0 μm.

[0041] In this embodiment, the tool substrate 1 is a cemented carbide substrate, but it is not limited to this. It can also be a substrate made of superhard materials such as cermet, ceramic, steel or cubic boron nitride.

[0042] Preparation of coated cutting tools The method for preparing the surface composite coating cutting tool in this embodiment includes the following steps: (1) Prepare tool base 1: Table 1 Composition of Tool Matrix 1

[0043] According to Table 1, the mixed powder of the tool matrix composition is pressed, sintered, and ground to manufacture WC-Co cemented carbide matrix with the cutting tool shape specified by ISO standards. Among them, the tool shape of the three matrix types M01, M02, and M03 is WNMG080408, and the tool shape of the matrix types M04 and M05 is WNMG080408-XM.

[0044] (2) Bottom binder layer 3: To prepare indexable coated cutting tools, a CVD coating furnace, such as a Bernex BPX530L CVD coating equipment, is used for coating. The bottom binder layer 3 is deposited on the tool substrate 1 using existing conventional CVD processes, and the coating composition is TiN. One reactive gas is used to deposit the bottom binder layer 3, and the deposition conditions are shown in Table 2.

[0045] Table 2 Deposition process of bottom bonding layer 3

[0046] (3) Lower wear-resistant layer 4: The lower wear-resistant layer 4 is deposited on the bottom adhesive layer 3 using one reactive gas. The deposition conditions are shown in Table 3.

[0047] Table 3. Deposition process of the lower wear-resistant layer 4

[0048] Under limited deposition process conditions, the thickness of the lower wear-resistant layer 4 is highly correlated with the deposition time. The coating thickness can be controlled by adjusting the deposition time.

[0049] (4) Middle bonding layer 5: The middle bonding layer 5 is deposited on the lower wear-resistant layer 4 using two reactive gases. The deposition process of the middle bonding layer 5 is divided into TA layer 51 and OA layer 52.

[0050] The depositional TA layer was obtained under the conditions shown in Tables 4-6.

[0051] Table 4. Deposition process of Ti compound layer 511 in TA layer

[0052] Table 5. Deposition process of TiAl compound layer 512 in TA layer

[0053] Table 6. Deposition process of TA layer 51

[0054] The depositional conditions for layer OA52 are shown in Table 7.

[0055] Table 7 Deposition process of OA layer 52

[0056] (5) Deposition of α-Al2O3 coating 6: An α-Al2O3 coating 6 was deposited on the surface of the middle adhesive layer 5, and the deposition conditions are shown in Table 8.

[0057] Table 8. Deposition process of α-Al2O3 coating 6

[0058] Under the limited deposition process conditions, the thickness of the α-Al₂O₃ coating 6 is highly correlated with the deposition time. The thickness of the α-Al₂O₃ coating 6 can be adjusted by changing the deposition time of the α-Al₂O₃ growth layer.

[0059] (6) Deposited surface layer 7: A surface layer 7 was deposited on the surface of the α-Al₂O₃ coating 6 under the following deposition conditions: Surface layer 7 process ST1: 4.3 vol% TiCl₄, 47.1 vol% N₂, and the balance H₂, at a temperature of 1005 °C, a deposition pressure of 600 mbar, and a deposition time of 90 min. Surface layer 7 process ST2: 4.3 vol% TiCl₄, 47.1 vol% N₂, and the balance H₂, at a temperature of 1005 °C, a deposition pressure of 300 mbar, and a deposition time of 120 min.

[0060] The deposition process parameters for each layer of the surface composite coating cutting tools CT01-CT10 are shown in Table 9.

[0061] Table 9. Deposition process of each layer for CT01-CT10 cutting tools

[0062] The thickness of each layer in the surface composite coating 2 can be adjusted according to time.

[0063] Thickness detection of surface composite coating 2 The thickness of each coating layer can be observed using SEM or metallographic microscopy. A vertical cross-section containing the coating is obtained by cutting along the vertical direction of the blade with a diamond saw blade. After mounting, grinding, and polishing, the cross-section is observed using SEM or metallographic microscopy. Alternatively, a vertical cross-section containing the coating is obtained by cutting along the vertical direction of the blade with a FIB, and then observed using TEM. The thickness of each layer of the prepared CT01-CT10 tools is shown in Table 10.

[0064] Table 10 Thickness of each layer in composite coating 2 on the surface of CT01-CT10 cutting tools (unit: μm)

[0065] a-Al2O3 coating texture orientation detection The texture orientation of the α-Al₂O₃ coating was calculated based on XRD diffraction analysis data. TC(hkl) is defined as follows: (1-1) in, I(hkl) = (hkl) (Measured intensity of reflection) I0(hkl) = Standard intensity of reflection based on the standard powder diffraction data (hkl) of the applied JCPDF card No. 10-0173. n = the number of reflections used in the calculation (here: n = 12), (hkl) i The (hkl) used i The reflective crystal planes are (012), (104), (110), (113), (116), (018), (214), (300), (1010), (0210), (0012) and (2110).

[0066] like Figure 2 As shown, according to the XRD diffraction pattern, the (1010) peak (2θ=76.88°) of α-Al2O3 (JCPDF card number: 10-0173) overlaps with the (222) peak (2θ=76.77°) of TiCN (JCPDF card number: 42-1489). Therefore, the intensity of the TiCN (222) peak needs to be subtracted when calculating the intensity of the (1010) peak of α-Al2O3. According to the standard diffraction pattern of TiCN (JCPDF card number: 42-1489), the intensities of the (111) peak and the (222) peak of TiCN are as follows: , (1-2) The actual intensity value of the TiCN(222) peak is: (1-3) The actual intensity of the (1010) peak of α-Al2O3 (JCPDF card number: 10-0173) is: (1-4) According to equations (1-2), (1-3), and (1-4), the actual intensity of the (1010) peak of α-Al2O3 (JCPDF card number: 10-0173) after deducting the (222) peak intensity of TiCN (JCPDF card number: 42-1489) can be calculated. The texture orientation of the α-Al2O3 coating 6 of the cutting tools CT01-CT10 of the present invention can be calculated according to equations (1-1) and (1-4), and the results are shown in Tables 11 and 12.

[0067] Table 11 Texture Orientation of α-Al2O3 (JCPDF Card No.: 10-0173)

[0068] Table 12 Texture Orientation of α-Al2O3 (JCPDF Card No.: 10-0173)

[0069] α-Al₂O₃ coating 6: Structure and columnar crystal size detection The microstructure and columnar crystal morphology of the α-Al₂O₃ coating were observed and measured using SEM. A vertical cross-section containing the coating was obtained by cutting along the direction perpendicular to the upper and lower surfaces of the blade using a diamond saw blade. After mounting, grinding, and polishing, the cross-section was observed using SEM-SE mode. For the CT01 blade of this invention, the average width of the columnar crystal grains was measured at 50% of the thickness along the α-Al₂O₃ growth direction on the cross-section perpendicular to the coating surface. The average width was 0.59 μm, the thickness of α-Al₂O₃ was 8.0 μm, and the h / d ratio was 13.6. Using the same calculation method, the h / d ratios of the α-Al₂O₃ coatings for the CT02-CT10 blades were calculated to be 12.8, 13.9, 12.7, 12.2, 14.5, 12.9, 13.5, 13.2, and 13.4, respectively. The thickness of each coating layer could be observed using SEM or a metallographic microscope. A vertical section containing the coating is obtained by cutting along the vertical surface of the blade with a diamond saw blade. After mounting, grinding, and polishing, the section is observed by SEM or metallographic microscope.

[0070] Comparative Example This comparative example provides a comparative cutting tool, the preparation method of which includes: Tool DT01 uses the same substrate and groove shape as tool CT02, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT01. The middle bonding layer process is as follows: Step 1: Deposition at 1005℃ and 30kPa using a single reactive gas stream, introducing 0.96 vol% TiCl4, 35.5 vol% N2, 2.1 vol% CH4, 0.5 vol% HCl, and the balance H2, for 35 min. Step 2: Deposition at 1005℃ and 6kPa using a single reactive gas stream, introducing 1.73 vol% TiCl4, 39.5 vol% N2, 0.45 vol% CH3CN, 1.86 vol% CO, 0.45 vol% AlCl3, and the balance H2, for 40 min. The third step involves deposition at 1005℃ and 6.5 kPa using a single-gas reaction system: 25.5 vol% N2, 1.15 vol% CO2, 5.32 vol% CO, and the remainder H2, for 5 minutes. Next, an α-Al2O3 growth layer is deposited on the surface under the following conditions: 1000℃, 6 kPa, 1.83 vol% AlCl3, 0.19 vol% H2S, 2.67 vol% CO2, 0.74 vol% CO, 1.10 vol% HCl, and the remainder H2. The α-Al2O3 layer thickness is adjusted to 8.0 μm by adjusting the time. Finally, a surface TiN layer is deposited using the same Ti compound layer preparation process as the CT01 tool.

[0071] Tool DT02 uses the same substrate and groove shape as tool CT05, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT05. It also uses the same middle bonding layer process as tool DT01. The α-Al₂O₃ growth layer deposition conditions are as follows: temperature 1005℃, deposition pressure 5.5 kPa, 1.97 vol% AlCl₃, 0.68 vol% H₂S, 2.21 vol% CO₂, 0.31 vol% CO, 0.55 vol% HCl, and the balance H₂. The α-Al₂O₃ layer thickness is adjusted to 8.0 μm by adjusting the deposition time. The same surface layer process as CT01 is used.

[0072] Tool DT03 uses the same substrate and groove shape as tool CT06, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT06. It also uses the same middle bonding layer process as tool DT01. The α-Al2O3 growth layer deposition conditions are as follows: temperature 1010℃, deposition pressure 6.5kPa, 1.63 vol% AlCl3, 0.15 vol% H2S, 2.75 vol% CO2, 0.64 vol% CO, 0.32 vol% HCl, and the balance H2. The α-Al2O3 layer thickness is adjusted to 8.0 μm by adjusting the time. The same surface layer process as CT01 is used.

[0073] Tool DT04 uses the same substrate and groove shape as tool CT07, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT07. It also uses the same middle bonding layer process as tool DT01. The α-Al₂O₃ growth layer deposition conditions are as follows: temperature 1010℃, deposition pressure 7.5 kPa, 2.13 vol% AlCl₃, 0.45 vol% H₂S, 2.10 vol% CO₂, 0.36 vol% CO, 0.25 vol% HCl, and the balance H₂. The α-Al₂O₃ layer thickness is adjusted to 8.0 μm by adjusting the deposition time. The same surface layer process as CT01 is used.

[0074] Tool DT05 uses the same substrate and groove shape as tool CT10, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT10. It also uses the same middle bonding layer process as tool DT01. The α-Al₂O₃ growth layer deposition conditions are as follows: temperature 1007℃, deposition pressure 8kPa, 1.85 vol% AlCl₃, 0.42 vol% H₂S, 1.95 vol% CO₂, 0.45 vol% CO, 0.65 vol% HCl, and the balance H₂. The α-Al₂O₃ layer thickness is adjusted to 6.0 μm by adjusting the deposition time. The same surface layer process as CT01 is used.

[0075] Tool DT06 uses the same substrate and groove shape as tool CT08, and employs the same bottom bonding layer and lower wear-resistant layer preparation process as tool CT08. It also uses the same middle bonding layer process as tool DT01. The α-Al₂O₃ growth layer deposition conditions are as follows: temperature 1000℃, deposition pressure 4.5 kPa, 1.35 vol% AlCl₃, 0.15 vol% H₂S, 5.78 vol% CO₂, 1.56 vol% CO, 1.55 vol% HCl, and the balance H₂. The α-Al₂O₃ layer thickness is adjusted to 8.0 μm by adjusting the deposition time. The same surface layer process as CT01 is used.

[0076] Based on XRD analysis and equations (1-2), (1-3), and (1-4), the α-Al2O3 layer texture orientation values ​​of the comparative cutting tools DT01-DT06 were obtained using the calculation method in Example 1, as shown in Table 13.

[0077] Table 13 Texture orientation of α-Al2O3 (JCPDF card number: 10-0173) for DT01-DT06

[0078] Cutting Test 1 Comparative cutting tests were conducted on the CT01, CT02, CT03, CT04, CT05, CT09 and the comparative cutting tools DT01 and DT02 produced according to Example 1, which were subjected to stress relief treatment by sandblasting using conventional coating post-treatment methods.

[0079] The cutting tools described above were subjected to turning tests as shown in Table 14, and the cutting was performed in the following manner: (1) Continuous turning: The tool tip is continuously turned. Every 1 / 3 of the maximum lifespan, the tool tip is stopped and allowed to cool naturally. The tool tip is then observed and the wear value is measured. If the tool tip is not chipped and the wear value is less than 0.3 mm, the next round of cutting continues until the tool fails.

[0080] (2) Intermittent cutting: Cut with the tool tip for 25 seconds, then retract the tool to a safe position and wait for 25 seconds before continuing cutting. Repeat the above steps until the tool fails. The machining time corresponding to the tool wear value reaching 0.3 mm or chipping after tool turning life assessment. Stop and allow natural cooling every 1 / 3 time unit of maximum life, observe the tool tip and measure the wear value. If the tool tip is not chipped and the wear value is less than 0.3 mm, continue the next round of cutting until the tool fails. The machining time statistics are the tool tip cutting time.

[0081] Table 14 Turning Experiment Mode Table

[0082] Table 15 Comparison of Experimental Results

[0083] As shown in Table 15, under continuous turning conditions, the tool tip and workpiece remain in constant contact, and the temperatures of both remain within a relatively stable range. However, under intermittent turning conditions, the tool tip temperature rises during cutting and descends when turning stops. The tool tip is subjected to continuous high and low temperature changes, resulting in significant thermal shock, which greatly affects the coating performance. Table 15 also shows that under the same parameters, tool life decreases during intermittent turning. However, the coated tool of this invention exhibits significantly better turning life than the comparative tool under both turning conditions. Furthermore, the performance advantage of the cutting tool of this invention is more pronounced under intermittent turning conditions.

[0084] Cutting Test 2 Comparative cutting tests were conducted on the CT06, CT07, CT08, CT10 of the present invention produced according to Example 1 and the comparative cutting tools DT03, DT04, DT05 and DT06 of Example 2, which were subjected to stress relief treatment by sandblasting according to conventional coating post-treatment methods.

[0085] The cutting tools described above were subjected to turning tests as shown in Table 16.

[0086] (1) Continuous turning: The tool tip is continuously turned. Every 1 / 3 of the maximum lifespan, the tool tip is stopped and allowed to cool naturally. The tool tip is then observed and the wear value is measured. If the tool tip is not chipped and the wear value is less than 0.3 mm, the next round of cutting continues until the tool fails.

[0087] (2) Intermittent cutting: Cut with the tool tip for 25 seconds, then retract the tool to a safe position and wait for 25 seconds before continuing cutting. Repeat the above steps until the tool fails. The machining time corresponding to the tool wear value reaching 0.3 mm or chipping after the tool turning life assessment. Stop and allow natural cooling every 1 / 3 time unit of the maximum life, observe the tool tip and measure the wear value. If the tool tip is not chipped and the wear value is less than 0.3 mm, continue the next round of cutting until the tool fails. The machining time statistics are the tool tip cutting time. The machining time statistics are the tool tip cutting time. The machining time corresponding to the tool wear value reaching 0.3 mm after the final life assessment.

[0088] Table 16 Turning Experiment Mode Table

[0089] Table 17 Comparison of Experimental Results

[0090] As shown in Table 17, under the same parameters, the tool life decreases during intermittent turning. However, the coated tool of the present invention has a significantly better turning life than the comparative tool under both turning conditions. Moreover, the cutting tool of the present invention has a more obvious performance advantage under intermittent turning conditions, demonstrating its excellent wear resistance.

[0091] Cutting test 3 (impact resistance test) Comparative cutting tests were conducted on the CT01, CT02, CT03, CT04, CT05, CT09 of the present invention produced according to Example 1, and the comparative cutting tools DT01 and DT02 of Example 2.

[0092] The workpiece material was a longitudinally bisected, four-groove, heat-treated 1045 steel bar. The cutting speed was 220 m / min, the depth of cut was 1.5 mm, the feed rate was 0.20 mm / rev, the cutting method was intermittent wet cutting, and the cooling method was water cooling. The final lifespan was judged by the machining time or turning time reaching 5 minutes when chipping occurred at the tool tip with a notch depth of 0.3 mm. Six sets of tests were repeated for each example sample, and the average value was taken. The experimental results are shown in Table 18.

[0093] Table 18 Comparison of Experimental Results

[0094] As shown in Table 18, the impact resistance life of the coated cutting tools of the present invention is all higher than 200 seconds, while the impact resistance life of the comparative cutting tools is all lower than 60 seconds. The impact resistance performance of the coated cutting tools of the present invention is significantly better than that of the comparative cutting tools.

[0095] Cutting Test 4 (Impact Resistance Test) Comparative cutting tests were conducted on the CT06, CT07, CT08, and CT10 of the present invention, produced according to Example 1, and the comparative cutting tools DT04, DT05, and DT06 of Example 2, respectively.

[0096] The workpiece material was a longitudinally bisected, four-groove, heat-treated 1045 steel bar. The cutting speed was 220 m / min, the depth of cut was 2.0 mm, the feed rate was 0.30 mm / rev, the cutting method was intermittent wet cutting, and the cooling method was water cooling. The final lifespan was judged by the machining time or turning time reaching 5 minutes when chipping occurred at the tool tip with a notch depth of 0.3 mm. Six sets of tests were repeated for each example sample, and the average value was taken. The experimental results are shown in Table 19.

[0097] Table 19 Comparison of Experimental Results

[0098] As shown in Table 19, the impact resistance life of the coated cutting tools of the present invention is 300 seconds with the cutting tip intact, while the impact resistance life of the comparative tools is less than 60 seconds. The impact resistance performance of the coated cutting tools of the present invention is significantly better than that of the comparative tools, demonstrating its superior impact resistance.

[0099] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A surface composite coated cutting tool characterized in that, The tool includes a tool substrate (1) and a surface composite coating (2) disposed on the tool substrate (1). The surface composite coating (2) contains at least one layer of α-Al2O3 coating (6) prepared by chemical vapor deposition. The α-Al2O3 coating (6) has a preferred texture orientation relative to the {018} and {1010} planes of the crystal. The texture coefficient satisfies the following characteristics: 6.0≤TC(018)+TC(1010)<12.0, and 3.0<TC(018)<10.0, 2.0≤TC(1010)<9.

0.

2. The surface composite coating cutting tool according to claim 1, characterized in that, The surface composite coating (2) also includes a lower wear-resistant layer (4), which is disposed between the α-Al2O3 coating (6) and the tool substrate (1). The lower wear-resistant layer (4) is composed of Ti compound and has an average thickness of 1.0 μm to 18 μm.

3. The solid composite coated cutting tool of claim 2, wherein, The surface composite coating (2) further includes a middle adhesive layer (5), which is disposed between the α-Al2O3 coating (6) and the lower wear-resistant layer (4). The middle adhesive layer (5) includes one or more TA layers (51) and one oxide OA layer (52) from bottom to top. The TA layer (51) has a Ti compound layer (511) and a TiAl compound layer (512) from bottom to top. The total thickness of the TA layer (51) is 0.1μm to 1.5μm, and the average thickness of the middle adhesive layer (5) is 0.1μm to 2.0μm.

4. The solid composite coated cutting tool of claim 3, wherein, The surface composite coating (2) also includes a bottom adhesive layer (3), which is disposed between the lower wear-resistant layer (4) and the tool substrate (1). The bottom adhesive layer (3) is composed of a Ti compound and has an average thickness of 0.1 μm to 3 μm.

5. The solid composite coated cutting tool of claim 4, wherein, The surface composite coating (2) further includes a surface layer (7), which is disposed on the α-Al2O3 coating (6). The surface layer (7) is composed of a Ti compound and has an average thickness of 0.1 μm to 3.0 μm.

6. The solid body composite coated cutting tool according to any one of claims 1-5, characterized in that, The α-Al2O3 coating (6) has a thickness of 1.0 μm to 18.0 μm, and the microstructure of the α-Al2O3 coating (6) is a fibrous columnar structure. The average width of the columnar crystal grains at 50% of the thickness along the growth direction of the α-Al2O3 coating (6) on the cross section perpendicular to the α-Al2O3 coating (6) is set as d, and the thickness of the α-Al2O3 coating (6) is set as h. The ratio of h to d is h / d≥12.

7. The solid body composite coated cutting tool according to any one of claims 1-5, characterized in that, The texture coefficient of the surface composite coating (2) is represented by TC(hkl), which is defined as follows: in, I( hkl )=( hkl ) the measured intensity of the reflected light, I 0( hkl =Based on the standard powder diffraction data of the applied JCPDF card No. 10-0173 ( hkl The standard intensity of reflection, n is the number of reflections used in the calculation, n=12. ( hkl ) i The (used) hkl ) i The reflective crystal planes are (012), (104), (110), (113), (116), (214), (300), (018), (1010), (0210), (0012) and (2110).

8. The solid body composite coated cutting tool according to any one of claims 1-5, characterized in that, The total thickness of the surface composite coating (2) is 2μm to 35μm.

9. A method of making a surface composite coated cutting tool according to any one of claims 1-8, characterized in that, Includes the following steps: A surface composite coating (2) is deposited on the tool substrate (1). The surface composite coating (2) contains at least one layer of α-Al2O3 coating (6) prepared by chemical vapor deposition. The deposition process conditions of the α-Al2O3 coating (6) are as follows: deposition temperature 980℃~1010℃, deposition pressure 4kPa~20kPa, and initial introduction of 1.0vol%~6.0vol% AlCl3 gas, 0.5vol%~3.0vol% CO2 gas, and 0.8vol%~6.0vol% CO2 gas. The deposition process involves introducing 1% CO gas and the remainder H2 gas for 30–90 minutes, followed by the introduction of 3.0 vol%–10.0 vol% AlCl3 gas, 0.5 vol%–5.0 vol% CO2 gas, 1.5 vol%–10.0 vol% CO gas, 0.2 vol%–1.0 vol% H2S gas, 0.3 vol%–2.5 vol% HCl gas, and the remainder H2 gas. The volume fraction V of CO2 gas in the subsequently introduced deposition gas is... CO2 Volume fraction V of AlCl3 gas AlCl3 The ratio V CO2 / V AlCl3 The volume fraction V of H2S gas is 0.1–0.

7. H2S V is the ratio of the volume fraction of oxygen-containing gas composed of CO2 and CO to the sum of their volume fractions. H2S / (V CO2 +V CO The concentration of 0.03 to 0.15 and the deposition time are 30 min to 1000 min.

10. The method of making a surface composite coated cutting tool according to claim 9, wherein, The surface composite coating (2) further includes a lower wear-resistant layer (4) and a middle adhesive layer (5). The lower wear-resistant layer (4) is disposed between the α-Al2O3 coating (6) and the tool substrate (1). The lower wear-resistant layer (4) is deposited using a CVD process. The middle adhesive layer (5) is disposed between the α-Al2O3 coating (6) and the lower wear-resistant layer (4). The middle adhesive layer (5) is deposited using a CVD process. The deposition process of the middle adhesive layer (5) is carried out using a coating furnace with two air inlets. Ti compound layer (511) for depositing TA layer: deposition temperature 930℃~1010℃, deposition pressure 0.8kPa~3kPa, deposition time 30min~70min. Two mixed gases are introduced into the coating furnace. The first mixed gas VT1 consists of 1.5vol%~9.0vol% TiCl4 gas, 3.0vol%~18.0vol% N2 gas, 0.5vol%~3.0vol% CH4 gas, and the balance H2 gas. The second mixed gas VT2 consists of 0.7vol%~3.0vol% NH3 gas and the balance H2 gas. The volume ratio of the first mixed gas VT1 to the second mixed gas VT2 is 1.5~6.0, and the volume fraction of N2 gas is V. N2 Volume fraction V of NH3 gas NH3 Ratio V N2 / V NH3 The volume fraction V of CH4 gas is 18–70. CH4 The ratio V to the total volume fraction of nitrogen-containing gas CH4 / (V N2 +V NH3 The volume fraction V of TiCl4 gas is 0.10–0.

50. TiCl4 Volume fraction V of NH3 gas NH3 The ratio V TiCl4 / V NH3 The value ranges from 5.0 to 30. The TiAl compound layer (512) for depositing the TA layer: deposition temperature 950℃~1010℃, deposition pressure 1.0kPa~4.0kPa, deposition time 10min~70min. Two mixed gases are introduced into the coating furnace. The first mixed gas VA1 consists of 1.5vol%~9.0vol% TiCl4 gas, 1.0vol%~6.0vol% AlCl3 gas, 3.0vol%~5.0vol% CO gas, 7.0vol%~18.0vol% N2 gas, and the balance H2. The second mixed gas VA2 consists of 0.8vol%~3.0vol% NH3 gas and the balance H2 gas. The volume ratio of the first mixed gas VA1 to the second mixed gas VA2 is 1.5~6.0, and the volume fraction of N2 is V... N2 Volume fraction V of NH3 NH3 The ratio V N2 / V NH3 The volume fraction V of TiCl4 gas is 10–50. TiCl4 Volume fraction V of NH3 gas NH3 The ratio V TiCl4 / V NH3 The value ranges from 2.5 to 20.

0. Deposition of oxide OA layer (52): Deposition temperature 950℃~1010℃, deposition pressure 2kPa~6kPa. The coating is first deposited using a two-gas alternating deposition method. The first gas mixture VO1 consists of 3.0 vol%~12.0 vol% TiCl4 gas and the balance H2, while the second gas mixture VO2 consists of 1.8 vol%~6.5 vol% AlCl3 gas and the balance H2. When one gas enters the coating furnace for CVD deposition, the other gas does not enter the coating furnace, but... The gas enters the exhaust pipe through a bypass pipe and is discharged. The single deposition time of the first mixed gas VO1 is 1 min to 3 min, and the single deposition time of the second mixed gas VO2 is 2 min to 5 min. The deposition is carried out in an alternating pattern of VO1, VO2, VO1, VO2, with each VO1 and VO2 deposition constituting one group, repeated 3 to 10 times. Then, 2.0 vol% to 5.0 vol% CO2 gas, 4.0 vol% to 12.0 vol% CO gas, and the balance H2 are introduced. The volume fraction of CO gas V... CO Volume fraction of CO2 gas V CO2 The ratio V CO / V CO2 The value is 1.0 to 3.0, and the deposition time is 3 min to 15 min.

11. The method for preparing a surface composite coating cutting tool according to claim 10, characterized in that, The surface composite coating (2) also includes a bottom adhesive layer (3), which is deposited using a CVD process.

12. The method of making a surface composite coated cutting tool according to claim 11 wherein, The surface composite coating (2) further includes a surface layer (7), which is deposited using a CVD process.

13. The application of a surface composite coating cutting tool as described in any one of claims 1 to 8 or a surface composite coating cutting tool prepared by the preparation method as described in any one of claims 9 to 12 in the fields of steel, cast iron and stainless steel.

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