Composite coating of cutter for efficient cutting of aerospace titanium alloy and preparation method of composite coating

Abstract

The invention discloses a composite coating of a cutter for efficient cutting of aerospace titanium alloy and a preparation method of the composite coating. The composite coating sequentially comprises a transition layer, a periodic composite layer and a functional layer from the base body side of the cutter to the surface side of the coating, the wear resistance, the high temperature resistance and the oxidation resistance of the tool in the titanium alloy cutting process are improved, the bonding strength of the coating and the matrix is enhanced, the preparation technology is simplified, the cost is reduced, the service life of the tool is prolonged, the machining efficiency of the tool is improved, and the machining cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of machining tools, and in particular relates to a composite coating for a tool used for efficient cutting of aerospace titanium alloys and a preparation method thereof. Background Art

[0002] Titanium and its alloys are increasingly used in aerospace and other fields due to their excellent comprehensive properties, including low density, high specific strength, corrosion resistance, high temperature resistance, non-magnetic properties, and good weldability. However, during the cutting process, titanium alloys are prone to sticking, flaking, and seizures due to their low deformation coefficient, high tool tip stress, high cutting temperature, high chemical activity, severe adhesive and diffusion wear, high elastic recovery, and high chemical affinity. This can lead to sharp increases in tool temperature, accelerated tool wear, and even complete tool damage, limiting production efficiency and increasing manufacturing costs.

[0003] At present, the low cutting amount used in titanium alloy processing seriously restricts production efficiency, and the existing tool coating technology is difficult to meet the needs of efficient cutting. The existing coatings are easily softened and oxidized at high temperatures and lose their protective effect; some coatings are not firmly bonded to the substrate and are easily peeled off under the repeated action of cutting forces; and some coating preparation processes are complicated and the cost is too high, which is not conducive to large-scale application. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a composite coating for high-efficiency cutting tools for aerospace titanium alloys, which comprises a transition layer, a periodic composite layer and a functional layer in sequence from the tool substrate side to the coating surface side; the transition layer has the same chemical composition as the first composite layer, and is composed of a compound represented by Ti1-xAlxN; the periodic composite layer has an alternating stacking structure in which the first composite layer and the second composite layer are alternately repeated more than twice; the second composite layer has the same chemical composition as the functional layer, and is composed of a compound represented by Ti1-ᵧ-zSiᵧBzN.

[0005] Preferably, the thickness of the transition layer is 0.3-1 μm, the thickness of the periodic composite layer is 1-3 μm, and the thickness of the functional layer is 0.8-1.5 μm.

[0006] Preferably, the first composite layer and the second composite layer are alternately stacked 2-5 times.

[0007] A method for preparing a composite coating for a tool used for efficient cutting of aerospace titanium alloys comprises the following steps: S1. Clean and polish the surface of the tool base; S2. Using physical vapor deposition (PVD) technology, a compound represented by Ti1-xAlxN is deposited on the surface of the tool substrate as a transition layer; S3. Continue to use PVD technology to alternately deposit the first composite layer (Ti1-xAlxN) and the second composite layer (Ti1-ᵧ-zSiᵧBzN) to form a periodic composite layer; S4. Depositing a compound represented by Ti1-ᵧ-zSiᵧBzN on the surface of the periodic composite layer as a functional layer.

[0008] Preferably, in the tool substrate pretreatment step, the tool substrate is immersed in a metal cleaning agent aqueous solution for cleaning for 8-15 minutes, then rinsed in deionized water for 3-8 minutes, then immersed in anhydrous ethanol for ultrasonic cleaning for 10-20 minutes, and finally the tool substrate is blown dry with compressed gas and placed in a drying oven for drying.

[0009] Preferably, when depositing the transition layer, the deposition temperature is 380-450° C., the nitrogen flow rate is 45-60 sccm, the argon flow rate is 18-30 sccm, the target power is 1.8-3 kW, and the deposition time is 25-40 minutes.

[0010] Preferably, when preparing the periodic composite layer, the deposition time of each of the first composite layer and the second composite layer is 10-25 minutes.

[0011] Preferably, when the functional layer is deposited, the deposition temperature is 430-500°C, the nitrogen flow rate is 55-70sccm, the argon flow rate is 28-40sccm, the target power is 2.5-3.5kW, and the deposition time is 35-50 minutes. The beneficial effects of the present invention are: The composite coating provided by the present invention has high hardness, can effectively resist wear during the titanium alloy cutting process, and extend the service life of the tool; the coating material can still maintain good mechanical properties at high temperatures, and is suitable for high-temperature cutting processing of aerospace titanium alloys; the composite coating has good antioxidant properties, can prevent the tool surface from oxidizing during the cutting process, and ensure the stable performance of the tool; the coating has high bonding strength with the substrate: the design of the transition layer enhances the bonding force between the coating and the tool substrate, and reduces the peeling phenomenon of the coating during the cutting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention. Example

[0014] First, pre-treat the tool substrate: Select a carbide tool substrate and immerse it in a metal cleaner solution for 10 minutes. The metal cleaner effectively removes oil and impurities from the substrate surface. Rinse it in deionized water for 5 minutes to remove residual detergent. Then, ultrasonically clean it in anhydrous ethanol for 15 minutes. Ultrasonic cleaning further removes tiny impurities and moisture. Finally, use compressed air to cool the tool substrate and dry it in a drying oven to ensure a dry and clean surface.

[0015] Next, the transition layer is prepared: PVD technology is used to deposit a Ti0.5Al0.5N transition layer on the tool substrate. The deposition temperature is 400°C, at which atoms have sufficient energy to migrate and deposit without causing excessive thermal impact on the substrate. A nitrogen flow rate of 50 sccm and an argon flow rate of 20 sccm ensure the stability of the deposition process and the quality of the coating. The target power is 2 kW, and the deposition time is 30 minutes. By precisely controlling these parameters, the transition layer thickness is approximately 0.5 μm, and the composition is uniform.

[0016] The next step is to fabricate periodic composite layers: a first composite layer of Ti0.5Al0.5N and a second composite layer of Ti0.4Si0.3B0.3N are deposited alternately, with each layer deposited for 15 minutes three times. During the deposition process, parameters such as gas flow and target power are strictly controlled to ensure consistent thickness and quality of each layer. The total thickness of the periodic composite layers is approximately 1.5μm. This alternating layer structure effectively disperses stress, improving the coating's toughness and impact resistance.

[0017] Finally, the functional layer is deposited on the surface of the periodic composite layer. A Ti0.4Si0.3B0.3N functional layer is deposited at a temperature of 450°C. The higher temperature helps enhance atomic diffusion and bonding, forming a dense coating structure. The nitrogen flow rate is 60 sccm, the argon flow rate is 30 sccm, the target power is 2.5 kW, and the deposition time is 40 minutes. By optimizing these parameters, the functional layer thickness is approximately 1 μm, and it exhibits excellent wear resistance, high temperature resistance, and oxidation resistance. Example

[0018] First, the tool substrate is pretreated: similar to Example 1, the surface of the cemented carbide tool substrate is cleaned and polished to ensure the cleanliness and flatness of the substrate surface.

[0019] Then prepare the transition layer: A Ti0.4Si0.3B0.3N transition layer was deposited at a temperature of 420°C, which better balances atomic migration and substrate thermal stability. A nitrogen flow rate of 55 sccm, an argon flow rate of 25 sccm, a target power of 2.2 kW, and a deposition time of 35 minutes resulted in a transition layer thickness of approximately 0.6 μm, further improving the bonding strength between the coating and the substrate.

[0020] The next step was to fabricate a periodic composite layer by alternating the deposition of a first Ti0.6Al0.4N composite layer and a second Ti0.5Si0.2B0.3N composite layer. Each composite layer was deposited for 20 minutes, and the deposition was repeated four times. The total thickness of the periodic composite layer was approximately 2 μm. By increasing the number of alternations and the thickness of each layer, the performance of the periodic composite layer was further optimized, improving the coating's toughness and impact resistance.

[0021] Finally, the functional layer is deposited: a Ti0.5Si0.2B0.3N functional layer is deposited at a temperature of 480°C. Higher temperatures facilitate a denser functional layer structure. A nitrogen flow rate of 65 sccm, an argon flow rate of 35 sccm, a target power of 2.8 kW, and a deposition time of 45 minutes achieve a functional layer thickness of approximately 1.2 μm, enhancing the coating's wear, high-temperature, and oxidation resistance. Example

[0022] First, the tool substrate is pretreated: a high-speed steel tool substrate is selected, and the surface is cleaned and polished according to the pretreatment method of Example 1 to remove impurities and oxide layers on the substrate surface.

[0023] Next, a transition layer was prepared: a Ti0.4Al0.6N transition layer was deposited at 380°C, although the temperature was appropriately lowered to account for the thermal stability of the high-speed steel substrate. A nitrogen flow rate of 48 sccm, an argon flow rate of 18 sccm, a target power of 1.8 kW, and a deposition time of 28 minutes were used, resulting in a transition layer thickness of approximately 0.4 μm, ensuring a good bond between the transition layer and the substrate and subsequent coatings.

[0024] The next step was to fabricate a periodic composite layer: a first composite layer of Ti0.4Al0.6N and a second composite layer of Ti0.3Si0.4B0.3N were deposited alternately, with each layer deposited for 12 minutes over five alternating depositions. The total thickness of the periodic composite layer was approximately 1.8 μm. By adjusting the composite layer composition and deposition times, the performance of the periodic composite layer was optimized, improving the coating's toughness and impact resistance.

[0025] Finally, the functional layer was deposited: a Ti0.3Si0.4B0.3N functional layer was deposited at a temperature of 430°C. The optimal temperature facilitates the formation of a high-performance functional layer. A nitrogen flow rate of 58 sccm, an argon flow rate of 28 sccm, a target power of 2.3 kW, and a deposition time of 38 minutes resulted in a functional layer thickness of approximately 0.9 μm, enhancing the coating's wear, high-temperature, and oxidation resistance.

[0026] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A composite coating for high-efficiency cutting tools for aerospace titanium alloys, characterized in that: From the tool substrate side toward the coating surface side, it includes a transition layer, a periodic composite layer and a functional layer in sequence; the transition layer has the same chemical composition as the first composite layer and is composed of a compound represented by Ti1-xAlxN; the periodic composite layer has an alternating stacking structure in which the first composite layer and the second composite layer are alternately repeated more than twice; the second composite layer has the same chemical composition as the functional layer and is composed of a compound represented by Ti1-ᵧ-zSiᵧBzN.

2. The composite coating for high-efficiency cutting tools for aerospace titanium alloys according to claim 1, characterized in that: The thickness of the transition layer is 0.3-1 μm, the thickness of the periodic composite layer is 1-3 μm, and the thickness of the functional layer is 0.8-1.5 μm.

3. The composite coating for high-efficiency cutting tools for aerospace titanium alloys according to claim 1, characterized in that: The first composite layer and the second composite layer are alternately stacked 2-5 times.

4. A method for preparing a composite coating for a high-efficiency cutting tool for aerospace titanium alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Clean and polish the surface of the tool base; S2. Using physical vapor deposition (PVD) technology, a compound represented by Ti1-xAlxN is deposited on the surface of the tool substrate as a transition layer; S3. Continue to use PVD technology to alternately deposit the first composite layer (Ti1-xAlxN) and the second composite layer (Ti1-ᵧ-zSiᵧBzN) to form a periodic composite layer; S4. Depositing a compound represented by Ti1-ᵧ-zSiᵧBzN on the surface of the periodic composite layer as a functional layer.

5. The method for preparing a composite coating for a tool for high-efficiency cutting of aerospace titanium alloys according to claim 4, characterized in that: In the tool substrate pretreatment step, the tool substrate is immersed in a metal cleaning agent aqueous solution for cleaning for 8-15 minutes, then rinsed in deionized water for 3-8 minutes, then immersed in anhydrous ethanol for ultrasonic cleaning for 10-20 minutes, and finally the tool substrate is blown dry with compressed gas and placed in a drying oven for drying.

6. The method for preparing a composite coating for aerospace titanium alloy high-efficiency cutting tool according to claim 4, characterized in that: When the transition layer is deposited, the deposition temperature is 380-450° C., the nitrogen flow rate is 45-60 sccm, the argon flow rate is 18-30 sccm, the target power is 1.8-3 kW, and the deposition time is 25-40 minutes.

7. The method for preparing a composite coating for aerospace titanium alloy high-efficiency cutting tool according to claim 4, characterized in that: When preparing the periodic composite layer, the deposition time of each of the first composite layer and the second composite layer is 10-25 minutes.

8. The method for preparing a composite coating for aerospace titanium alloy high-efficiency cutting tool according to claim 4, characterized in that: During the deposition of the functional layer, the deposition temperature is 430-500° C., the nitrogen flow rate is 55-70 sccm, the argon flow rate is 28-40 sccm, the target power is 2.5-3.5 kW, and the deposition time is 35-50 minutes.

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