Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance

Abstract

This invention discloses a Ti-Al-V-C nanocomposite coating with both high oxidation resistance and high wear resistance, belonging to the field of coating technology. In this Ti-Al-V-C nanocomposite coating, the C element content is 10.02-12.40 at.%, the V element content is 73.73-83.52 at.%, the Ti element content is 4.89-10.99 at.%, and the Al element content is 1.56-3.36 at.%. It is a nanocomposite structure containing VC phase, AlCV2 phase, and V4C3 phase. The VC phase preferentially grows along the (111) crystal plane, the AlCV2 crystal phase preferentially grows along the (200) crystal plane, and the V4C3 phase preferentially grows along the (220) crystal plane. This invention prepares a coating with high hardness, high wear resistance, and high oxidation resistance by optimizing the Al, Ti, and V element content in the coating.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and specifically to a Ti-Al-VC nanocomposite coating that combines high oxidation resistance and high wear resistance. Background Technology

[0002] Nanocomposite coatings have attracted widespread attention due to their special physical and chemical properties. Properties related to the material surface, such as hardness, high temperature resistance, oxidation resistance, friction resistance, and corrosion resistance, are currently hot research topics. Coatings composed of two or more phases with different structures can be called nanocomposite coatings, which are mainly divided into three categories: (1) nc-ceramic / a-ceramic composite coatings, such as nc-TiN / a-Si3N4, nc-ZrN / a-Si3N4, nc-TiAlN / a-AlN, etc.; (2) nc-ceramic / nc-ceramic composite coatings, such as nc-MeN / nc-C3N4, etc.; (3) nc-ceramic / metal composite coatings, such as nc-ZrN / Cu, nc-ZrN / Ni, nc-ZrN / Y, etc.

[0003] Vanadium carbide (VC) is an important functional material among transition metal carbides, possessing a series of excellent properties, such as good mechanical properties and a low coefficient of friction. However, under high load and high speed friction conditions, it exhibits poor resistance to high-temperature oxidation and abrasive wear, easily leading to severe wear and premature failure, thus limiting its application in high-temperature conditions and failing to meet the requirements of coated tools in high-speed dry cutting. This invention aims to further improve the overall performance of VC coatings by introducing Al and Ti elements. Summary of the Invention

[0004] To further improve the wear resistance and high-temperature oxidation resistance of existing VC coatings, the present invention aims to provide a Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance. By employing arc ion plating and high-power pulsed composite magnetron sputtering technology, appropriate amounts of Al and Ti elements are doped into the VC coating to form a Ti-Al-VC coating, thus preparing a Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance is deposited on a substrate such as a pure metal, hard alloy substrate, stainless steel sheet or silicon wafer, with a V transition layer between the nanocomposite coating and the substrate; the thickness of the nanocomposite coating is 1.5-2μm.

[0007] The Ti-Al-VC nanocomposite coating contains 10.02-12.40 at.% C, 73.73-83.52 at.% V, 4.89-10.99 at.% Ti, and 1.56-3.36 at.% Al.

[0008] The Ti-Al-VC nanocomposite coating is a nanocomposite structure containing VC phase, AlCV2 phase and V4C3 phase. The VC phase grows preferentially along the (111) crystal plane, the AlCV2 crystal phase grows preferentially along the (200) crystal plane, and the V4C3 phase grows preferentially along the (220) crystal plane.

[0009] The Ti-Al-VC nanocomposite coating has a hardness higher than 25 GPa, an elastic modulus that is stable between 260 and 310 GPa, and an H / E ratio that can reach up to 0.083.

[0010] The Ti-Al-VC nanocomposite coating is deposited on a substrate using a combination of high-power pulsed magnetron sputtering and arc ion plating. During deposition, AlTi and V targets were selected, and the base vacuum level was 6 × 10⁻⁶. -3 Above Pa, the bias voltage is controlled at -100 to -200V, the deposition pressure is 0.5 to 0.8Pa, the AlTi target is connected to a high-power pulsed magnetron sputtering power supply with an AlTi target power of 0.4 to 2.0kW, and the V target is connected to an arc ion plating power supply with a V target current of 85-100A.

[0011] Furthermore, during the deposition of the Ti-Al-VC nanocomposite coating, Ar and C2H2 are introduced, wherein the flow rate of Ar is 120-150 sccm, the flow rate of C2H2 is 10-30 sccm, and the total gas flow rate is 130-180 sccm.

[0012] The preparation process of this Ti-Al-VC nanocomposite coating specifically includes the following steps:

[0013] (1) Fix the cleaned substrate onto the rotating frame inside the coating chamber and evacuate the vacuum to 6×10. -3 Pa or higher; the AlTi target is connected to a high-power pulsed magnetron sputtering power supply, and the V target is connected to an arc ion plating power supply;

[0014] (2) The substrate is subjected to glow discharge cleaning and ion bombardment cleaning in sequence. The glow discharge cleaning process is as follows: the furnace cavity is heated to 400°C, argon gas is introduced at 200-250 sccm, the pulse bias voltage is set to -800V (duty cycle 70-90%), and the substrate is subjected to glow discharge cleaning for 15-20 min. The ion bombardment cleaning process is as follows: after glow discharge cleaning, the V target is turned on, and then the V target arc source current is set to 85-100A, the arc source voltage is set to 20-22V, the deposition pressure is set to 0.5Pa-0.8Pa, the argon gas flow rate is kept at 120-150 sccm, and the substrate is bombarded for 8-10 min under the bias voltage of -800V (duty cycle 70-90%).

[0015] (3) Deposit a V transition layer to improve the bonding strength between the working layer and the substrate. The process of depositing the V transition layer is as follows: after glow discharge cleaning and ion bombardment cleaning, set the bias voltage to -100V to -200V (duty cycle 70% to 90%), turn on the V target, set the V target arc source current to 85 to 100A, the arc source voltage to 20 to 20.3V, the argon gas flow rate to 120 to 150 sccm, adjust the deposition pressure to 0.5Pa to 0.8Pa, and deposit the V transition layer for 15 to 20 minutes.

[0016] (4) Deposition of Ti-Al-VC nanocomposite coating.

[0017] The design mechanism of this invention is as follows:

[0018] This invention employs pulsed DC and high-power pulsed composite magnetron sputtering technology to deposit Ti-Al-VC nanocomposite coatings on substrates such as cemented carbide sheets, SUS304 stainless steel, or single-crystal Si wafers.

[0019] While VC coatings possess excellent mechanical properties and a low coefficient of friction, their poor resistance to high-temperature oxidation and wear limits their application in high-speed cutting of difficult-to-machine workpieces. Doping VC coatings with appropriate amounts of antioxidants Al and Ti, without significantly impacting their mechanical properties, is an effective way to improve their frictional resistance and high-temperature oxidation resistance. Al₂O₃ films effectively prevent further oxidation within the coating, providing excellent thermal and chemical barriers. The prepared Ti-Al-VC nanocomposite coating exhibits numerous interfaces, resulting in significantly different properties compared to binary coatings. This multi-component composite coating enhances tool toughness and high-temperature oxidation resistance.

[0020] In high-temperature environments, aluminum readily combines with oxygen to form a high-hardness, highly dense Al2O3 film, exhibiting excellent red hardness and thermal barrier properties. The higher the Al content, the denser the Al2O3 film formed on the coating surface, resulting in better oxidation resistance and tribological properties. At high temperatures, the VC coating readily reacts with external oxygen, and the low-melting-point V2O5 (660℃) formed during friction leads to a decline in coating performance. The introduction of Al to form an Al2O3 film effectively hinders the diffusion of oxygen into the coating, thus improving the thermal stability of the Ti-Al-VC coating.

[0021] This invention introduces appropriate amounts of Al and Ti elements into the VC coating. As the temperature increases, the lubrication effect of graphite carbon begins to decrease at 400℃. At 500℃, an appropriate amount of Ti rapidly generates loose and porous TiO2, providing a certain lubrication effect. The rate at which Al reacts with O2 to form an Al2O3 protective film is lower than the rate at which TiO2 is formed. This achieves the formation of both lubricating TiO2 and antioxidant Al2O3 protective films at increasing temperatures. When friction occurs at temperatures above 500℃, VC reacts with O2 to generate lubricating VO2 and V2O5.

[0022] The advantages and beneficial effects of this invention are as follows:

[0023] 1. The Ti-Al-VC nanocomposite coating prepared by this invention has high wear resistance and obvious wear resistance effect.

[0024] 2. The Ti-Al-VC nanocomposite coating of this invention maintains the original high oxidation resistance, high strength and high toughness of the VC coating, gives full play to the synergistic effect of V, Al and Ti, and achieves a self-lubricating multi-component composite coating with advantages such as high oxidation resistance, high wear resistance and good thermal stability.

[0025] 3. The Ti-Al-VC nanocomposite coating of this invention has broad application prospects and is suitable for high-speed dry cutting of various difficult-to-machine materials, which can significantly improve cutting efficiency and tool life.

[0026] 4. The Ti-Al-VC nanocomposite coating of this invention has excellent high-temperature oxidation resistance, good mechanical properties and tribological properties, and the coated cutting tools are suitable for heavy-duty intermittent machining. Attached Figure Description

[0027] Figure 1 The surface and cross-sectional morphology of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers are shown in Example 1.

[0028] Figure 2The XRD patterns of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers are shown in Example 1.

[0029] Figure 3 The hardness and elastic modulus of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers are shown in Example 1.

[0030] Figure 4 The scratch morphology images of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers are shown in Example 1.

[0031] Figure 5 The friction coefficient and wear rate of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers are shown in Example 1.

[0032] Figure 6 The wear morphology of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers is shown in Example 1.

[0033] Figure 7 The elemental content of Ti-Al-VC nanocomposite coatings prepared by arc ion plating and high-power pulsed magnetron sputtering under different AlTi target powers in Example 1 is shown. Detailed Implementation

[0034] The present invention will be further described in detail below through embodiments.

[0035] Example 1:

[0036] This embodiment describes the preparation of Ti-Al-VC nanocomposite coatings with different AlTi target powers.

[0037] This embodiment involves depositing a Ti-Al-VC nanocomposite coating on a single-crystal Si wafer (40mm×40mm×0.67mm), a cemented carbide wafer (25mm×25mm×3.0mm), and a stainless steel wafer (35mm×35mm×1.0mm). The coating is achieved using arc ion plating and high-power pulsed magnetron sputtering techniques. The specific operational steps are as follows:

[0038] (1) After polishing the cemented carbide substrate, place it in an ultrasonic cleaner along with a pre-prepared single-crystal silicon wafer and a 304 stainless steel sheet. Clean them sequentially in acetone and alcohol solutions for 20 minutes each, then dry them with high-purity N2 (99.999%). Secure the substrate in the designated position on the fixture. After degaussing the vacuum chamber, open the vacuum chamber door and fix the substrate to the rotating frame inside the coating chamber using wire. Evenly arrange the metal AlTi target (Al to Ti atomic ratio 1:1 in the AlTi target) and V target on the inner wall of the magnetron sputtering furnace. Adjust the substrate's fixing position so that it faces the target surface to prevent uneven coating preparation due to varying surface deposition distances. After adjusting the fixture position and checking for any foreign matter residue in the vacuum chamber, close the furnace door.

[0039] (2) Vacuuming: Since the molecular pump cannot operate when the pressure inside the vacuum chamber exceeds 4.0 Pa, the vacuuming process is divided into two steps. First, vacuuming begins at atmospheric pressure using a TRP-90 type roughing pump. When the vacuum level inside the vacuum chamber reaches 4.0 Pa, the molecular pump is turned on to accelerate it. When the vacuum level reaches 3.0 Pa, the valve of the IP2200 type molecular pump (pumping speed ≥1600 L / s) is opened to further evacuate the vacuum chamber until the pressure inside the vacuum chamber reaches 6 × 10⁻⁶ Pa. -3 Below Pa, turn on the heating source to heat the vacuum chamber, setting the final temperature to 400℃ and the alarm temperature to 450℃. During heating, the rotating frame should rotate clockwise at 40Hz to ensure uniform heating of the substrate. Continue heating until the temperature stabilizes at 400℃ and the vacuum level reaches 6×10⁻⁶. -3 Pa.

[0040] (3) Glow discharge cleaning of the vacuum chamber: The background vacuum level of the vacuum chamber is evacuated to 6.0 × 10⁻⁶. -3 After Pa, heat to 400℃, then apply a -800V bias voltage with a bias duty cycle of 87%, and introduce Ar (99.999%) into the vacuum chamber at a flow rate of 200 sccm. Adjust the throttle valve to maintain the working pressure at 1.5 Pa, and perform glow discharge cleaning for 15 min.

[0041] (4) Bombardment cleaning of the target surface: Maintain Ar (99.999%) flow rate at 100 sccm, turn on the V target, and then set the V target arc source current to 90A, arc source voltage to 20-22V, deposition pressure to 0.6Pa, pulse bias to -800V, bias duty cycle to 87%, and bombardment time to 8min. Remove contaminant layers and oxides from the substrate and target surface.

[0042] (5) When depositing the transition layer, Ar (99.999%) is introduced, the gas flow rate is kept at 150 sccm, the V target is turned on, and then the V target arc source current is set to 90A, the arc source voltage is 20~20.3V, the pulse bias voltage is -150V, the bias voltage duty cycle is 70%, the working pressure is maintained at 0.8Pa, and the time is 15min.

[0043] (6) When preparing the Ti-Al-VC coating, lower the bias voltage to -150V, the bias duty cycle is 50%, and introduce Ar (99.999%) and C2H2 (99.999%). The Ar flow rate is 135sccm and the C2H2 flow rate is 15sccm. Keep the total flow rate at 150sccm. Turn on the AlTi target and V target with a power of 0.4~1.2kW and 90A respectively. Keep the working pressure at 0.6Pa by adjusting the throttle valve.

[0044] The morphology and performance tests of the various Ti-Al-VC nanocomposite coatings prepared in this embodiment are as follows:

[0045] The phase composition of the coating was analyzed using X-ray diffraction (XRD). Data was acquired using a stepped scanning method, with Cu target Kα characteristic spectral line (λ = 0.154056 nm) as the incident X-ray. The tube voltage was 40 kV, the tube current was 40 mA, the diffraction angle (2θ) scanning range was 20°–80°, the scanning step size was 0.02°, and the counting time per step was 0.2 s. The surface and cross-sectional morphology of the coating were observed using an S4800 field emission scanning electron microscope (SEM), and the chemical composition of the coating was analyzed using an electron probe microanalysis (EPMA, Shimadzu, EPMA1600). The hardness and elastic modulus of the coating were tested using a nanoindenter (Anton Paar, TTX-NHT-3). To eliminate the influence of matrix effects on the measurement results, the indentation depth of the nanoindenter was ensured to be no more than 1 / 10 of the coating thickness, and 15 points were measured and the average value was taken. The bonding strength between the coating and the SUS304 stainless steel substrate was measured using a scratch tester (Anton Paar RST-3). The diamond tip diameter was 200 μm, and the parameters were as follows: loading speed 6 mm / min; scratch length 3 mm; load set at 100 N. The experimental data were recorded in real time by computer.

[0046] The coefficient of friction was tested on a tribological testing machine (Anton Paar THT). Al₂O₃ balls with a diameter of 5.99 mm (hardness 22±1 GPa) were used for the friction pair. The sliding linear velocity was 0.1 m / s, the normal load was 4 N, the rotation radius was 6 mm, and the sliding distance was 100 m. The friction experiment was conducted at room temperature (22±3℃) and humidity (30%). Each sample was tested three times. The coating wear rate W was calculated using the formula W=V / (F×S) (V is the wear volume, F is the normal load, and S is the sliding distance). Furthermore, the morphology of the coating after wear was observed using a super depth-of-field microscope (VHX-1000C, Keyence).

[0047] Figure 1 The surface and cross-sectional morphologies of the Ti-Al-VC nanocomposite coatings under different AlTi target powers are shown. SEM images reveal that the nanocomposite coatings exhibit a distinct amorphous-encapsulated nanocrystalline structure. The coatings are all dense and free of obvious pores or defects.

[0048] Figure 2 The XRD patterns of the Ti-Al-VC nanocomposite coatings under different AlTi target powers are shown. The Ti-Al-VC nanocomposite coatings exhibit preferred growth orientations on the (111) and (200) and (220) crystal planes. The diffraction peak intensities of the VC phase on the (111) crystal plane, the AlCV2 phase on the (200) crystal plane, and the V4C3 phase on the (220) crystal plane are significantly increased, indicating that the crystallinity of the Ti-Al-VC nanocomposite coating is improved.

[0049] Figure 3 To test the nanohardness and elastic modulus of Ti-Al-VC nanocomposite coatings under different AlTi target powers using a nanoindenter, the hardness of the nanocomposite coating first increased and then decreased with increasing target power. At an AlTi target power of 0.8 kW, the nanocomposite coating achieved a maximum hardness of 25.50 GPa and a maximum elastic modulus of 307.5 GPa.

[0050] Figure 4 The morphology of Ti-Al-VC nanocomposite coatings after scratch testing under different AlTi target powers is shown. The film / substrate adhesion first increases and then decreases with increasing modulation ratio. As the target power increases, the sputtered particle energy is injected into the substrate, and the H / E and H of the coating are affected. 3 / E *2 The increased value results in better resistance to elastic and plastic deformation, making it less prone to cracking and peeling, thus improving the adhesion of the coating.

[0051] Figure 5The friction coefficient of the Ti-Al-VC nanocomposite coating after tribological wear tests under different AlTi target powers showed a trend of first decreasing and then increasing. The friction coefficient was the lowest at an AlTi target power of 0.6 kW, reaching 0.66. Morphology images of AlTi target powers of 0.4, 0.8, 1.0, and 1.2 kW show that a large amount of wear debris exists in the wear tracks. The wear debris that detaches during the friction process participates in the friction test, leading to an increase in the friction coefficient. The wear track morphology at 0.6 kW shows relatively less wear debris and a relatively lower friction coefficient.

[0052] Figure 6 The wear track morphology of Ti-Al-VC nanocomposite coatings under different AlTi target powers is shown. When the target power is 0.4kW to 1.2kW, the wear track width is wider and the depth is deeper, resulting in a higher wear rate. With the increase of Al content, the wear track is narrowest and shallowest when the target power is 1.2kW, exhibiting the best wear resistance.

[0053] Figure 7 The elemental contents of the Ti-Al-VC nanocomposite coatings prepared in Example 1 under different AlTi target powers are shown. It can be seen that in this Ti-Al-VC nanocomposite coating, the C element content ranges from 10.02-12.40 at.%, the V element content is 73.73-83.52 at.%, the Ti element content is 4.89-10.99 at.%, and the Al element content is 1.56-3.36 at.%. This invention controls the elemental contents in the coating within a suitable range by selecting appropriate deposition processes and corresponding process parameters (gas flow rate, target type, AlTi target power, V target current, etc.), thereby obtaining a Ti-Al-VC nanocomposite coating with excellent comprehensive performance.

[0054] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A Ti-Al-VC nanocomposite coating possessing both high oxidation resistance and high wear resistance, characterized in that: The Ti-Al-VC nanocomposite coating is deposited on a metal or silicon substrate, with a V transition layer between the nanocomposite coating and the substrate. In this Ti-Al-VC nanocomposite coating, the C element content is 10.02-12.40 at.%, the V element content is 73.73-83.52 at.%, the Ti element content is 4.89-10.99 at.%, and the Al element content is 1.56-3.36 at.%; the thickness of the nanocomposite coating is 1.5-5.0 μm. The Ti-Al-VC nanocomposite coating is a nanocomposite structure containing VC phase, AlCV2 phase and V4C3 phase. The VC phase grows preferentially along the (111) crystal plane, the AlCV2 crystal phase grows preferentially along the (200) crystal plane, and the V4C3 phase grows preferentially along the (220) crystal plane. The Ti-Al-VC nanocomposite coating has a hardness higher than 25 GPa, an elastic modulus that is stable between 260 and 310 GPa, and an H / E ratio that can reach up to 0.

083.

2. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 1, characterized in that: The Ti-Al-VC nanocomposite coating was deposited on the substrate using a combination of high-power pulsed magnetron sputtering and arc ion plating. During the deposition process, AlTi and V targets were selected as the targets, and the base vacuum level was 6 × 10⁻⁶. -3 Above Pa, the substrate bias voltage is -100 ~ -200 V, the deposition pressure is 0.5 ~ 0.8 Pa, the AlTi target is connected to a high-power pulsed magnetron sputtering power supply, the AlTi target sputtering power is 0.4 ~ 2.0 kW, and the V target is connected to an arc ion plating power supply, the V target current is 85 ~ 100 A.

3. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 2, characterized in that: During the deposition of the Ti-Al-VC nanocomposite coating, Ar and C2H2 are introduced, with the Ar flow rate being 120~150 sccm, the C2H2 flow rate being 10~30 sccm, and the total gas flow rate being 130~180 sccm.

4. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 2, characterized in that: The preparation process of this Ti-Al-VC nanocomposite coating specifically includes the following steps: (1) Fix the cleaned substrate onto the rotating frame inside the coating chamber and evacuate the vacuum to 6×10. -3 Pa or higher; the AlTi target is connected to a high-power pulsed magnetron sputtering power supply, and the V target is connected to an arc ion plating power supply; (2) The substrate is subjected to glow discharge cleaning and ion bombardment cleaning in sequence; (3) Deposit a V transition layer to improve the bonding strength between the working layer and the substrate; (4) Deposit Ti-Al-VC nanocomposite coating.

5. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 4, characterized in that: In step (2), the glow discharge cleaning process is as follows: heat the furnace cavity to 400 ℃, introduce argon gas at 200~250 sccm, set the pulse bias voltage to -800 V, the duty cycle to 70~90%, and perform glow discharge cleaning on the substrate for 15~20 min.

6. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 4, characterized in that: In step (2), the ion bombardment cleaning process is as follows: after glow discharge cleaning, turn on the V target, then set the V target arc source current to 85-100 A, the arc source voltage to 20-22 V, the deposition pressure to 0.5 Pa-0.8 Pa, and maintain the argon flow rate at 120-150 sccm. Bombard the target for 8-15 min under the conditions of -800V bias and duty cycle of 70-90%.

7. The Ti-Al-VC nanocomposite coating with both high oxidation resistance and high wear resistance according to claim 4, characterized in that: In step (3), the process of depositing the V transition layer is as follows: after glow discharge cleaning and ion bombardment cleaning, the bias voltage is set to -100V~-200V, the duty cycle is 70%~90%, the V target is turned on, the V target arc source current is set to 85-100A, the arc source voltage is 20~22V, the argon gas flow rate is 150~160 sccm, the deposition pressure is adjusted to 0.5 Pa~0.8 Pa, and the V transition layer is deposited for 15~20 min.

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