Heat treatment process for improving hardness, toughness and wear resistance of Zr-B-N / ZrO2 multilayer composite coating

Abstract

The invention discloses a heat treatment process for improving the hardness, toughness and wear resistance of a Zr-B-N / ZrO2 multi-layer composite coating, and belongs to the technical field of coatings. According to the process, a vacuum tube furnace is adopted for carrying out heat treatment on a Zr-B-N / ZrO2 multilayer composite coating deposited through a high-power pulse magnetron sputtering and pulse direct-current magnetron sputtering composite technology, the process comprises a heating stage, a heat preservation stage and a cooling stage which are sequentially carried out, the heating rate of the heating stage is 5-15 DEG C / min, the temperature T of the heat preservation stage is 500-800 DEG C, and the temperature T of the cooling stage is 20-30 DEG C; the cooling rate of the cooling stage is 3-6 DEG C / min. The heat treatment process of the multi-layer composite coating is simple, and industrial production is easy to realize. The Zr-B-N / ZrO2 multilayer composite coating prepared by the invention has good hardness, toughness and wear resistance, and can significantly enhance the wear resistance and heat resistance of a matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a heat treatment process for improving the hardness, toughness and wear resistance of a Zr-BN / ZrO2 multilayer composite coating. Background Art

[0002] With the rapid development of high-end manufacturing fields such as aerospace, automobile manufacturing, and precision mold processing, the demand for the application of difficult-to-machine materials such as high-temperature alloys and tungsten-molybdenum alloys is increasing. These difficult-to-machine materials have high cutting forces, easy chipping, high cutting temperatures, severe work hardening, large cutting deformation, and short tool life during high-load intermittent cutting. These often lead to severe tool wear and breakage, increasing tool costs and reducing processing efficiency. The existing tool system faces severe challenges: cemented carbide tools are prone to adhesive wear at high temperatures, resulting in a short service life; while ceramic tools and cubic boron nitride tools have high hardness, their inherent brittleness significantly increases the risk of chipping during intermittent cutting, and the high manufacturing cost limits their large-scale application.

[0003] In response to the above technical bottlenecks, tool surface protective coating technology has become the key to breakthrough. Although traditional ZrB2 coatings have a high melting point, high hardness and excellent thermal conductivity, their intrinsic brittleness leads to insufficient resistance to crack propagation and is prone to sudden failure under impact loads. The Zr-BN nanocomposite coating formed by nitrogen doping effectively improves toughness by introducing the presence of a soft a-BN phase, but the high-temperature oxidation and volatilization of the amorphous BN phase seriously weakens the thermal stability of the Zr-BN coating. As a good thermal barrier material, ZrO2 has the advantages of good thermal stability, low thermal conductivity, and corrosion resistance.

[0004] Introducing a ZrO2 thermal barrier layer on the basis of the Zr-BN coating to construct a nano-multilayer structure can not only bring out the synergistic effect of the two, but also hinder dislocation movement through interface regulation and increase crack propagation resistance, thereby improving the hardness, toughness, wear resistance and heat resistance of the coating.

[0005] Related research has shown that vacuum heat treatment at an appropriate temperature can improve coating surface defects, reduce internal stress, refine the grain structure, and thus strengthen the coating. Optimizing the heat treatment process is expected to further improve coating performance. Therefore, the present invention uses a vacuum tube furnace to vacuum heat treat a Zr-BN / ZrO2 multilayer composite coating prepared by a combination of high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering to improve coating defects and enhance the coating's hardness, toughness, wear resistance, heat resistance, and cutting performance. Summary of the Invention

[0006] The purpose of the present invention is to provide a heat treatment process for improving the hardness, toughness and wear resistance of Zr-BN / ZrO2 multilayer composite coatings. The hardness, elastic modulus, H / E and H of the Zr-BN / ZrO2 multilayer composite coatings after heat treatment are improved. 3 / E *2 The value is high, with good hardness, toughness and wear resistance.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] The present invention is directed to heat treatment of a Zr-BN / ZrO2 multilayer composite coating to improve the hardness, toughness and wear resistance of the coating; the nano multilayer composite coating is formed by alternatingly stacking Zr-BN modulation layers and ZrO2 modulation layers; the heat treatment process is to use a vacuum tube furnace to heat treat the Zr-BN / ZrO2 multilayer composite coating, including a heating stage, a heat preservation stage and a cooling stage performed in sequence, and by controlling the process parameters of different heat treatment stages, the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating are improved; wherein: the heating rate in the heating stage is 5 to 15°C / min, the temperature T in the heat preservation stage is 500-800°C (preferably 550-670°C), and the cooling rate in the cooling stage is 3 to 6°C / min.

[0009] Furthermore, the heat treatment process specifically includes the following steps:

[0010] (1) The Zr-BN / ZrO2 multilayer composite coating sample was placed in a ceramic crucible, which was then placed in the vacuum tube of a vacuum tube furnace and evacuated to a vacuum degree of 1×10 -3 Pa or above;

[0011] (2) The coating sample is heat treated. The heat treatment process is as follows: heating to temperature T and keeping it at temperature T for 50 to 80 minutes. After the insulation is completed, the sample is cooled to room temperature and then taken out.

[0012] Furthermore, in step (2), the heating process is specifically as follows: first, heating to temperature T1 at a heating rate of 7°C / min, T1 = (T-90°C) ~ (T-110°C); then heating to temperature T2 at a heating rate of 10°C / min, T2 = (T-20°C) ~ (T-50°C); finally, heating to temperature T at a heating rate of 8°C / min.

[0013] Furthermore, the heat-treated Zr-BN / ZrO2 multilayer composite coating is formed by alternating Zr-BN modulation layers and ZrO2 modulation layers, wherein: the Zr-BN layer is a nano-composite structure formed by BN amorphous phase and ZrN nanocrystalline phase, and the ZrO2 layer is a columnar crystal structure formed by ZrO2 nanocrystalline phase.

[0014] Furthermore, after heat treatment, the coating hardness is greater than 30 GPa, the elastic modulus is greater than 380 GPa, the film-base bonding strength is greater than 45 N, the coating friction coefficient is less than 0.50, and the wear rate is less than 5×10 -6 mm 3 / (N·m).

[0015] Furthermore, the modulation period of the Zr-BN / ZrO2 multilayer composite coating is 65-110nm, and the number of periods is ≥8; the modulation ratio of the Zr-BN modulation layer and the ZrO2 modulation layer is 1:1 to 9:1.

[0016] Furthermore, the Zr-BN / ZrO2 multilayer composite coating is deposited on a single crystal Si wafer, a cemented carbide, and a cemented carbide tool substrate; the chemical composition of the Zr-BN / ZrO2 multilayer composite coating is, in atomic percentage, Zr 19.32-23.56 at.%, B 33.47-47.74 at.%, N 18.99-13.25 at.%, and O 9.72-33.97 at.%.

[0017] Furthermore, the Zr-BN / ZrO2 multilayer composite coating is deposited on a substrate by high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering composite coating technology, wherein the target materials are selected from metal Zr target and ZrB2 target (the purity of the target materials is 99.9wt.%); first, a metal Zr transition layer or a CrN transition layer is deposited on the substrate for 15 to 25 minutes, and then the Zr-BN / ZrO2 nano-multilayer composite coating is deposited. When depositing the Zr-BN / ZrO2 nano-multilayer composite coating, the background vacuum degree is 5×10 -3 Pa, the deposition pressure is adjusted to 0.5-0.8Pa, and then the Zr-BN modulation layer and the ZrO2 modulation layer are deposited alternately; when preparing the Zr-BN modulation layer, the Zr target and the ZrB2 target are turned on, the Zr target power is 0.4-2.0kw, the ZrB2 target power is 0.4-1.6kw, the bias voltage is set to 150V (duty cycle 50%), and Ar and N2 (or N2 / H2) mixed gas are introduced; when preparing the ZrO2 modulation layer, the bias voltage is maintained at -150V, the deposition pressure is 0.5-0.8Pa, the Zr target is turned on, the Zr target power is 0.4-2.0kw, and Ar and O2 are introduced; according to the thickness of the required modulation layer and the modulation ratio, the different target material opening time and gas introduction time are set.

[0018] Furthermore, when depositing the Zr-BN modulation layer, the flow rate of Ar is 94 sccm, the total flow rate of N2 (or N2 / H2 mixed gas) is 6 sccm, the volume ratio of N2 and H2 in the N2 / H2 mixed gas is 9:1, and the total gas flow rate is 100 sccm; when depositing the ZrO2 modulation layer, the flow rate of Ar is 94 sccm, the flow rate of O2 is 6 sccm, and the total gas flow rate is 100 sccm.

[0019] The design mechanism of the present invention is as follows:

[0020] The present invention uses a vacuum tube furnace to heat treat the Zr-BN / ZrO2 multilayer composite coating prepared by high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering composite technology, promotes coating crystallization, and improves coating performance. The increase in temperature can effectively enhance the diffusion capacity of elements inside the coating. The present invention reduces defects such as vacancies and holes in the coating by controlling the heating rate, holding temperature and time, and cooling rate during the coating heat treatment process, thereby improving the phase structure of the coating and increasing the density of the coating. Due to the presence of boron nitride in the coating, different heating rates are preferably selected in different temperature ranges. By optimizing the heat treatment temperature to regulate the microstructure of the Zr-BN / ZrO2 multilayer composite coating, the tool is given good toughness and wear resistance, making it suitable for high-speed dry cutting conditions, further improving the service life and processing efficiency of the tool.

[0021] The present invention adopts a vacuum tube furnace to perform heat treatment on the Zr-BN / ZrO2 multilayer composite coating, which has the advantages of no oxidation and no decarburization, can effectively adjust the internal stress of the coating, and improve the phase structure and service performance of the coating.

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

[0023] 1. The Zr-BN / ZrO2 multilayer composite coating after heat treatment of the present invention has the advantages of high hardness and good toughness, can significantly enhance the wear resistance of the base material, and has good chemical stability.

[0024] 2. After heat treatment, the Zr-BN / ZrO2 multilayer composite coating is a multilayer composite coating composed of a nanocomposite structure of ZrN nanocrystals embedded in a BN amorphous layer and a ZrO2 nanomodulation layer. The large lattice mismatch between the layers makes it difficult for dislocations to propagate and expand through the interface. It has the advantages of high hardness, high toughness, good wear resistance, and excellent heat resistance.

[0025] 3. The Zr-BN / ZrO2 multilayer composite coating after heat treatment has fewer surface defects, dense cross-sectional structure, high hardness, good toughness and good wear resistance; the wear rate is about 4.54×10 -6 mm 3 / (N·m).

[0026] 4. The heat treatment process of Zr-BN / ZrO2 multilayer composite coating has good repeatability. The prepared coating has a wider application prospect and can be used for high-speed cutting of various difficult-to-process materials, which has unique advantages.

[0027] 5. The Zr-BN / ZrO2 multilayer composite coating prepared by the present invention is suitable for the field of modern high-speed dry cutting, and can significantly improve the service life and processing efficiency of the tool; it can meet special working conditions such as high temperature, high load, ultra-low temperature, ultra-high vacuum, strong oxidation, strong radiation, etc., and has broad application prospects in high-speed cutting tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD patterns of Zr-BN / ZrO2 multilayer composite coatings after vacuum heat treatment at different temperatures.

[0029] Figure 2 Surface morphology of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures.

[0030] Figure 3 The cross-sectional morphology of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures.

[0031] Figure 4 Hardness and elastic modulus of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures.

[0032] Figure 5 The H / E value and H of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures 3 / E *2 value.

[0033] Figure 6 The scratch morphology of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures.

[0034] Figure 7 Friction coefficient and wear rate of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures.

[0035] Figure 8 Wear scar morphology of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below with reference to specific embodiments.

[0037] The present invention adopts a vacuum tube furnace to heat treat the Zr-BN / ZrO2 multilayer composite coating, and obtains the Zr-BN / ZrO2 multilayer composite coating with excellent comprehensive performance by controlling the heating rate, holding temperature and time, cooling rate, etc. in different stages.

[0038] (1) The sample with Zr-BN / ZrO2 multilayer composite coating was fixed in a ceramic crucible, and the vacuum degree of the vacuum tube was pumped to 1×10 -3 Pa or above;

[0039] (2) The Zr-BN / ZrO2 multilayer composite coating samples were subjected to a heating treatment to improve the coating microstructure and thereby enhance the mechanical and tribological properties of the coating;

[0040] During the heat treatment process, a step-by-step temperature increase method is adopted. First, the temperature is increased to temperature T1 at a heating rate of 7°C / min, where T1 = (T-90°C) to (T-110°C); then the temperature is increased to temperature T2 at a heating rate of 10°C / min, where T2 = (T-20°C) to (T-50°C); finally, the temperature is increased to temperature T at a heating rate of 8°C / min.

[0041] During the above heat treatment process, when the temperature is raised to T2 (close to the holding temperature T), the heating rate is reduced to achieve a buffering effect until the desired holding temperature is reached.

[0042] The Zr-BN / ZrO2 multilayer composite coating sample used in the following examples is composed of alternating Zr-BN modulation layers and ZrO2 modulation layers. The coating modulation period is 80 nm and the number of periods is 40. The modulation ratio of the Zr-BN modulation layer and the ZrO2 modulation layer is 7:1.

[0043] The Zr-BN / ZrO2 multilayer composite coating samples described in the following examples were deposited on substrates using a combination of high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering. The Zr-BN / ZrO2 multilayer composite coatings were deposited on single crystal Si wafers (40 mm × 10 mm × 0.67 mm) and cemented carbide substrates (25 mm × 25 mm × 2 mm) using a HiPIMS / Pulse DC composite magnetron sputtering system. The specific coating preparation process is as follows:

[0044] (1) All substrates were ultrasonically cleaned in deionized water and anhydrous ethanol for 15 min and dried, and then fixed on a rotating bracket in a vacuum chamber; the Cr target was connected to an arc power supply, the ZrB2 target was connected to a pulsed DC magnetron sputtering power supply, and the Zr target was connected to a high-power pulsed magnetron sputtering power supply; during the coating process, the working gas was Ar with a purity of 99.999%, and the reaction gases were N2 and O2 with a purity of both 99.999%.

[0045] (2) Glow discharge cleaning: Pump the background vacuum to 3.0×10 -3 Pa, heat the coating chamber to 300 ° C, apply -800 V bias, introduce Ar with a flow rate of 200 sccm, maintain the working pressure at 1.5 Pa, and perform glow discharge cleaning for 15 minutes to remove contaminants on the substrate surface.

[0046] (3) Ion bombardment cleaning: After glow discharge cleaning, the arc Cr target is turned on again for ion bombardment. The arc source current is set to 90A, the Ar flow rate is 100sccm, and the working pressure is maintained at 6×10 -1 Pa, ion bombardment cleaning for 10-30min to improve the membrane-base interface bonding and enhance the bonding strength of the coating.

[0047] (4) Deposition of CrN transition layer: The arc Cr target parameters were kept unchanged, the Ar flow rate was 50 sccm, the N2 flow rate was 200 sccm, and the working pressure was kept at 8×10 -1 Pa, and deposited CrN transition layer for 15 min to reduce the difference in thermal expansion coefficient between the coating and the substrate and improve the film / substrate bonding strength.

[0048] (5) Preparation of Zr-BN / ZrO2 multilayer composite coating: Set the bias voltage to -150 V (duty cycle 50%) and adjust the deposition pressure to 6×10 -1 Pa; then alternately deposited Zr-BN modulation layer and ZrO2 modulation layer; when preparing Zr-BN modulation layer, introduced Ar and N2 mixed gas, N2 flow rate was 6sccm, Ar flow rate was 94sccm, and the total flow rate of Ar and N2 was maintained at 100sccm, turned on Zr target and ZrB2 target, Zr target power was 1.2kw, ZrB2 target power was 1.0kw; when preparing ZrO2 modulation layer, maintained bias voltage -150V (duty cycle 50%), deposition pressure was 6×10 -1 Pa, the Zr target was turned on, the Zr target power was 1.2 kW, and Ar and O2 were introduced with an Ar flow rate of 94 sccm, an O2 flow rate of 6 sccm, and a total gas flow rate of 100 sccm. The target on-time and gas introduction time were set according to the desired modulation layer thickness and modulation ratio. Finally, a Zr-BN / ZrO2 multilayer composite coating was prepared. The chemical composition of the prepared Zr-BN / ZrO2 multilayer composite coating is shown in Table 1. The coating has a hardness of 30.25 GPa, an elastic modulus of 382.16 GPa, a bonding force of 41.92 N, a friction coefficient of 0.894, and a wear rate of 1.51×10 -5 mm 3 / (N·m).

[0049] Table 1 Chemical composition of Zr-BN / ZrO2 multilayer composite coating

[0050] Zr (at.%) B (at.%) N (at.%) O(at.%) 23.56 47.74 18.99 9.72

[0051] Example 1:

[0052] This example uses a vacuum tube furnace to perform vacuum heat treatment on the Zr-BN / ZrO2 multilayer composite coating to improve the coating structure and performance. The specific steps are as follows:

[0053] (1) The sample substrate of the Zr-BN / ZrO2 multilayer composite coating was fixed in a ceramic crucible and placed in a vacuum quartz tube in turn.

[0054] (2) Roughly evacuate to a pressure below 5 Pa, then open the upper valve and finely evacuate to a pressure of 1×10 -3 Pa, heated to 500°C at a heating rate of 7°C / min, then increased to 10°C / min and heated to 560°C. To slow down the temperature overshoot, the heating rate was reduced to 8°C / min and heated to the heat treatment temperature T. After keeping warm for 60 minutes, cooled to room temperature at a cooling rate of 4°C / min; the heat treatment temperatures T were 500°C, 600°C, 700°C and 800°C, respectively.

[0055] The morphology characterization and performance test of the heat-treated Zr-BN / ZrO2 multilayer composite coating are as follows:

[0056] The surface and cross-sectional morphologies of the coatings were observed using a JSM-7610F high-resolution field emission scanning electron microscope (FESEM), and the chemical composition of the coatings was determined using an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) analysis of the coating phase was performed. X-ray diffraction data were collected using a step-scan method, with the incident X-rays radiating from the Cu target Kα characteristic line (λ = 0.154056 nm). The tube voltage was 40 kV, the tube current was 40 mA, the diffraction angle (2θ) scanning range was 20° to 90°, the scanning step size was 0.02°, and the counting time per step was 0.2 s.

[0057] The nanohardness and elastic modulus of the coating were measured using a nanoindenter (Anton Paar, TTX-NHT-3). To eliminate substrate effects, the tip penetration depth was maintained at no more than 1 / 10 of the coating thickness. The average value was calculated for 15 measurements. The film / substrate bond strength between the coating and the YG8 cemented carbide substrate was measured using a scratch tester (Anton Paar RST-3). The diamond tip diameter was 200 μm, and the following parameters were used: a loading speed of 6 mm / min, a scratch length of 3 mm, and a set load of 100 N. The experimental data were recorded in real time by a computer.

[0058] The friction coefficient was measured using an Anton Paar THT tribometer. A 6mm diameter Al2O3 ball (hardness 22±1 GPa) was used as the friction pair. The sliding velocity was 0.1 m / s, the normal load was 2 N, the rotation radius was 8 mm, and the number of friction cycles was 1000 laps. The friction tests were conducted at room temperature (22±3°C) and 30% humidity. Each sample was tested three times. The coating wear rate (W) was calculated using the formula W=V / (F×S), where V is the wear volume, F is the load, and S is the sliding distance. The morphology of the worn coating was also observed using an ultra-depth-of-field microscope (VHX-1000C, Keyence).

[0059] After testing, the chemical composition of the Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment is: Zr 21.62at.%, B 43.18at.%, N 16.86at.%, O 18.23at.%.

[0060] Figure 1 The XRD patterns of Zr-BN / ZrO2 multilayer composite coatings after vacuum heat treatment at different temperatures are shown. As can be seen from the figure, the Zr-BN / ZrO2 multilayer composite coating mainly contains t-ZrO2 phases with (011), (112), and (013) crystal planes and fcc-ZrN phases with (111) and (200) crystal planes. As the annealing temperature increases, the diffraction peak intensity of the t-ZrO2 phase gradually increases and shifts to larger angles due to lattice contraction and the release of residual stress within the coating. When the annealing temperature reaches 800℃, the (101) crystal plane hcp-ZrB2 phase and the (200) crystal plane fcc-ZrO phase precipitate in the coating.

[0061] Figure 2 Figure 2 shows the surface morphology of Zr-BN / ZrO2 multilayer composite coatings after vacuum heat treatment at different temperatures. The as-deposited coating exhibits numerous surface defects, including particles, pores, and cracks. After vacuum annealing, these defects are significantly reduced. This is because vacuum annealing accelerates the diffusion rate of elements, promoting the diffusion and rearrangement of elements within the coating, thereby eliminating surface defects such as pores and cracks.

[0062] Figure 3 Figure 3 shows the cross-sectional morphology of Zr-BN / ZrO2 multilayer composite coatings after vacuum heat treatment at different temperatures. When annealed at 600°C, the cross-section of the multilayer coating is clear, the nanostructure remains intact, and the sublayers are tightly bonded. As the annealing temperature increases, the nanostructure gradually dissolves, and gaps appear between the coating and the substrate.

[0063] Figure 4The hardness and elastic modulus of the Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures are shown. As the vacuum annealing temperature increases, the hardness and elastic modulus of the coating first increase and then decrease. At 600°C, the coating's hardness and elastic modulus reach their maximum values of 32.75 GPa and 391.70 GPa, respectively.

[0064] Figure 5 The H / E value and H of Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures 3 / E *2 With the increase of vacuum annealing temperature, H / E and H 3 / E *2 The value shows a trend of increasing first and then decreasing. When the annealing temperature is 600℃, H / E and H 3 / E *2 The values both reach the maximum value of 0.084 and 0.190 respectively. The clear multilayer interface inhibits the formation of dislocations and improves the crack propagation resistance, thereby enhancing the toughness and plastic deformation resistance of the coating.

[0065] Figure 6 The scratch morphology of a Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures is shown. As the vacuum annealing temperature increases, the bonding strength first increases and then decreases. At 600°C, the bonding strength reaches 47.95N. At 800°C, adhesion failure between the coating and the substrate causes large-scale flaking of the coating.

[0066] Figure 7 The friction coefficient and wear rate of the Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures are shown. After vacuum annealing, the friction coefficient and wear rate of the coating show a significant downward trend. When the annealing temperature is increased to 800°C, the friction coefficient and wear rate of the coating drop to their lowest values, 0.507 and 4.54×10, respectively. -6 mm 3 / (N·m).

[0067] Figure 8 The wear scar morphology of the Zr-BN / ZrO2 multilayer composite coating after vacuum heat treatment at different temperatures is shown in the figure. As can be seen from the figure, after vacuum annealing, the furrows gradually become shallower and the pits gradually disappear, and the wear mode transforms from abrasive wear to oxidative wear.

[0068] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by other skilled in the art without expending creative labor falls within the scope of protection of the present invention.

Claims

1. A heat treatment process for improving the hardness, toughness and wear resistance of a Zr-BN / ZrO2 multilayer composite coating, characterized by: The nano multi-layer composite coating is formed by alternating Zr-BN modulation layers and ZrO2 modulation layers. The heat treatment process uses a vacuum tube furnace to heat treat the Zr-BN / ZrO2 multi-layer composite coating, including a heating stage, a heat preservation stage and a cooling stage performed in sequence. By controlling the process parameters of different heat treatment stages, the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multi-layer composite coating are improved. The heating rate in the heating stage is 5 to 15°C / min, the temperature T in the heat preservation stage is 500-800°C, and the cooling rate in the cooling stage is 3 to 6°C / min.

2. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1, characterized in that: The heat treatment process specifically includes the following steps: (1) The Zr-BN / ZrO2 multilayer composite coating sample was placed in a ceramic crucible, which was then placed in the vacuum tube of a vacuum tube furnace and evacuated to a vacuum degree of 1×10 -3 Pa or above; (2) The coating sample is heat treated. The heat treatment process is as follows: heating to temperature T and keeping it at temperature T for 50 to 80 minutes. After the insulation is completed, the sample is cooled to room temperature and then taken out.

3. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1 or 2, characterized in that: In step (2), the heating process is specifically as follows: first, heating to temperature T1 at a heating rate of 7°C / min, T1 = (T-90°C) ~ (T-110°C); then heating to temperature T2 at a heating rate of 10°C / min, T2 = (T-20°C) ~ (T-50°C); finally, heating to temperature T at a heating rate of 8°C / min.

4. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1 or 2, characterized in that: The heat-treated Zr-BN / ZrO2 multilayer composite coating is composed of alternating Zr-BN modulation layers and ZrO2 modulation layers, wherein the Zr-BN layer is a nanocomposite structure formed by BN amorphous phase and ZrN nanocrystalline phase, and the ZrO2 layer is a columnar crystal structure formed by ZrO2 nanocrystalline phase.

5. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1 or 2, characterized in that: After heat treatment, the coating hardness is greater than 30GPa, the elastic modulus is greater than 380GPa, the film-base bonding strength is greater than 45N, the coating friction coefficient is less than 0.50, and the wear rate is less than 5×10 -6 mm 3 / (N·m).

6. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1, characterized in that: The modulation period of the Zr-BN / ZrO2 multilayer composite coating is 65-110nm, and the number of periods is ≥8; the modulation ratio of the Zr-BN modulation layer to the ZrO2 modulation layer is 1:1 to 9:

1.

7. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 1, characterized in that: The Zr-BN / ZrO2 multilayer composite coating is deposited on a single crystal Si wafer, a cemented carbide and a cemented carbide tool substrate. Calculated by atomic percentage, the chemical composition of the Zr-BN / ZrO2 multilayer composite coating is as follows: Zr 19.32-23.56 at.%, B 33.47-47.74 at.%, N 18.99-13.25 at.%, and O 9.72-33.97 at.%.

8. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 6, characterized in that: The Zr-BN / ZrO2 multilayer composite coating is deposited on a substrate by using high-power pulsed magnetron sputtering and pulsed DC magnetron sputtering composite coating technology, wherein the target materials are selected from a metal Zr target and a ZrB2 target (the purity of the target materials is 99.9wt.%); a metal Zr transition layer or a CrN transition layer is first deposited on the substrate for 15 to 25 minutes, and then the Zr-BN / ZrO2 nano-multilayer composite coating is deposited. When depositing the Zr-BN / ZrO2 nano-multilayer composite coating, the background vacuum degree is 5×10 -3 Pa, the deposition pressure is adjusted to 0.5-0.8Pa, and then the Zr-BN modulation layer and the ZrO2 modulation layer are deposited alternately; when preparing the Zr-BN modulation layer, the Zr target and the ZrB2 target are turned on, the Zr target power is 0.4-2.0kw, the ZrB2 target power is 0.4-1.6kw, the bias voltage is set to 150V (duty cycle 50%), and Ar and N2 (or N2 / H2) mixed gas are introduced; when preparing the ZrO2 modulation layer, the bias voltage is maintained at -150V, the deposition pressure is 0.5-0.8Pa, the Zr target is turned on, the Zr target power is 0.4-2.0kw, and Ar and O2 are introduced; according to the thickness of the required modulation layer and the modulation ratio, the different target material opening time and gas introduction time are set.

9. The heat treatment process for improving the hardness, toughness and wear resistance of the Zr-BN / ZrO2 multilayer composite coating according to claim 8, characterized in that: When depositing the Zr-BN modulation layer, the flow rate of Ar is 94 sccm, the flow rate of N2 (or N2 / H2 mixed gas) is 6 sccm, the volume ratio of N2 to H2 in the N2 / H2 mixed gas is 9:1, and the total gas flow rate is 100 sccm; when depositing the ZrO2 modulation layer, the flow rate of Ar is 94 sccm, the flow rate of O2 is 6 sccm, and the total gas flow rate is 100 sccm.

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