A sputtering method for forming an interface metallurgical bonding coating

Abstract

The invention discloses a sputtering method for forming an interface metallurgical bonding coating, and belongs to the technical field of coating preparation. The sputtering process is two steps, in the first step of sputtering: the target discharge voltage is 400-800V, the pulse width is 30-100μs, the peak current is 100-300A, the peak voltage is 600-1000V, the substrate negative bias is 800-1000V, and the duty cycle is 50-60%; in the second step of sputtering: the target discharge voltage is 400-800V, the pulse width is 30-100μs, the peak current is 100-300A, the peak voltage is 600-1000V, the target composition is Ta or Cr, the substrate negative bias is 20-200V, and the duty cycle is 20-80%. The present invention can directly cause element interdiffusion between the coating and the substrate, and metallurgical bonding is formed without subsequent heat treatment, and the structure is dense and the mechanical properties are excellent.

Description

Technical field:

[0001] The invention relates to the technical field of coating preparation, and in particular to a sputtering method for forming an interface metallurgical bonding coating. Background technology:

[0002] Conventional magnetron sputtering is a commonly used physical vapor deposition method with many advantages, such as low deposition temperature, fast deposition speed, good uniformity of deposited thin films, and composition close to the target material composition. Its basic principle is to use the plasma containing argon gas to collide with secondary electrons under the action of electric field and alternating magnetic field to ionize and form Ar + After the ions are released, they are accelerated to fly towards the cathode target under the action of the electric field and bombard the cathode target with high energy, and neutral target particles are sputtered, which are deposited on the substrate surface without directional kinetic energy. When both the substrate and the target are metal materials, due to the low energy and directional kinetic energy of the sputtered particles, only van der Waals secondary bonds are formed at the interface in the deposited state (the atomic bond energy between the film and the substrate is only 3 to 70 kJ / mol), and the wettability of the film-substrate interface is poor. Under external force loading or thermal cycling, the coating in the deposited state cannot generally be used directly, and subsequent high-temperature heat treatment is required to allow the elements to diffuse between the film and the substrate before it can be used. However, many materials and workpieces are subject to stress and heat treatment limitations, and high-temperature heat treatment cannot be performed, otherwise the relevant workpieces will be directly deformed and scrapped.

[0003] The new high-power pulsed magnetron sputtering gives the sputtered particles the characteristic of high ionization, so that the sputtered metal ions can be deposited on the surface of the metal substrate with directional kinetic energy under the guidance of negative bias voltage, which can improve the wettability between the sputtered coating and the substrate. Most coating atoms can only form a physical bond with the substrate on the surface, and the bonding force is higher than that of conventional magnetron sputtering. However, the mutation of interface elements leads to lattice mismatch between the film-substrate interface, which will introduce higher interface stress. In the service environment of high stress and high thermal cycle, the coating still has a high risk of peeling at the interface, causing the overall coating to fail quickly. If the coating elements and the substrate can be mutually diffused at low temperature in the deposition state, the element mutation factors can be reduced, and the interface gradient pattern of the elements can be formed, that is, a metallurgical bond can be formed, then the practical application of sputtered coatings in extreme environments can be realized. Summary of the invention:

[0004] The purpose of the present invention is to provide a sputtering method for forming an interface metallurgical bonding coating. The method uses a high-power pulsed magnetron sputtering process to deposit a coating on the surface of a substrate. Elements directly diffuse between the deposited coating and the substrate to form a metallurgical bond, which greatly improves the bonding strength of the coating without the need for subsequent heat treatment.

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

[0006] A sputtering method for forming an interface metallurgical bonding coating comprises the following two steps:

[0007] (1) In the first stage, high-power pulsed magnetron sputtering was used with the following process parameters: target discharge voltage was 400-800 V, pulse width was 30-100 μs, peak current was 100-300 A, peak voltage was 600-1000 V, substrate negative bias voltage was -800--1000 V, duty cycle was 50-60%, high-purity Ar gas was filled to a vacuum degree of 0.2-3 Pa, and the time was 5-120 min.

[0008] (2) The second stage is high-power pulsed magnetron sputtering, with the following process parameters: target discharge voltage of 400-800 V, pulse width of 30-100 μs, peak current of 100-300 A, peak voltage of 600-1000 V, substrate negative bias of -20--200 V, duty cycle of 20-80%, high-purity Ar gas filled to a vacuum degree of 0.2-0.5 Pa, and time of 30-480 min.

[0009] In high-power pulsed magnetron sputtering, the target material used contains one or more elements of Ni, Al, Cr and Ta (pure metal target or alloy target).

[0010] In high-power pulsed magnetron sputtering, the distance between the target substrates is 25 to 80 mm.

[0011] The high-power pulse magnetron sputtering is carried out under low temperature conditions, and the deposition temperature is 150-350°C.

[0012] The advantages and beneficial effects of the present invention are:

[0013] 1. The process of the present invention enables the sample to obtain a sputtered coating with metallurgical bonding directly formed between the coating and the substrate under low temperature conditions, without post-processing, which can greatly improve the coating bonding strength and increase the service life of the coating. In addition, the obtained coating is dense, has excellent mechanical properties, and does not affect the mechanical properties of the prefabricated substrate. It can be used in special tools, artillery barrel inner bores and other workpieces serving in extreme environmental conditions.

[0014] 2. There is an interfacial diffusion zone with a thickness of more than 0.5 microns between the deposited coating prepared by the method of the present invention and the substrate. Description of the drawings:

[0015] Figure 1 The morphology of the sputtered tantalum coating obtained on the gun steel substrate using the process implemented in this patent.

[0016] Figure 2 for Figure 1 EDS energy spectrum of the deposited sample interface. Specific implementation method:

[0017] The present invention is further described in detail below through examples.

[0018] Example 1

[0019] The substrate is made of 30CrNi3MoV alloy steel, the sample size is 15mm×10mm×2mm, the purity of the tantalum target is 99.99wt%, the distance between the substrate and the target is 60mm, and the substrate is loaded into the working room after sandblasting and surface cleaning; the working room pressure is pumped to less than 7×10 -2 Pa, turn on the heater to heat the sample to 200 degrees Celsius, and then pump the pressure of the working chamber to less than 7.0×10 -3 Pa.

[0020] The first stage of high-power pulsed magnetron sputtering was carried out: the power supply used was a high-power pulsed magnetron sputtering power supply, in which the target discharge voltage was 700V, the pulse width was 50μs, the peak current was 230A, the peak voltage was 1000V, the substrate negative bias was -980V, the duty cycle was 60%, and high-purity Ar gas was filled to a vacuum degree of 0.25Pa for 30min.

[0021] Then the second stage of high-power pulsed magnetron sputtering was carried out: the sputtering power supply parameters and vacuum degree of the first stage were kept unchanged, the substrate negative bias voltage was adjusted to -100 V, the duty cycle was 70%, and the time was 420 min.

[0022] The cross-section of the deposited tantalum coating is observed, such as Figure 1 As shown in the figure, it can be seen that the film layer is dense and well bonded to the irregular substrate surface, and no shielding holes appear. The energy spectrum element line scan is performed on the membrane-substrate interface, and the element distribution results are shown in Figure 2 As shown, an interfacial interdiffusion zone of nearly 1 micron has appeared between the deposited coating and the substrate, indicating that an interfacial metallurgical bond has been formed between the tantalum coating and the substrate.

[0023] Example 2

[0024] The substrate is made of 304 steel, the sample size is 15mm×10mm×2mm, the purity of the Cr target is 99.99wt%, the distance between the substrate and the target is 80mm, and the substrate is polished to 400 with sandpaper, cleaned and loaded into the working room; the working room pressure is pumped to less than 5×10 -2 Pa, turn on the heater to heat the sample to 300 degrees Celsius, and then pump the pressure of the working chamber to less than 7.0×10 -3 Pa.

[0025] The first stage of high-power pulsed magnetron sputtering was carried out: the power supply used was a high-power pulsed magnetron sputtering power supply, in which the target discharge voltage was 600V, the pulse width was 100μs, the peak current was 200A, the peak voltage was 1000V, the substrate negative bias was -900V, the duty cycle was 50%, and high-purity Ar gas was filled to a vacuum degree of 2Pa for 40min.

[0026] Then the second stage of high-power pulsed magnetron sputtering was carried out: the sputtering power supply parameters and vacuum degree of the first stage were kept unchanged, the substrate negative bias voltage was adjusted to -80V, the duty cycle was 80%, and the time was 240min.

[0027] The cross-section observation of the deposited tantalum coating shows that the film has a dense structure and is well bonded to the irregular substrate surface, with no shielding holes. The energy spectrum element line scan at the film-substrate interface shows that a 1.2-micron interdiffusion zone appears between the coating and the substrate in the deposited state, indicating that an interfacial metallurgical bond has been formed between the chromium coating and the substrate.

[0028] Example 3

[0029] The substrate is made of N5 high-temperature alloy substrate, the sample size is 15mm×10mm×2mm, the purity of Al target is 99.99wt%, the distance between substrate and target is 40mm, and the substrate is polished to 1000 with sandpaper, cleaned and loaded into the working room; the working room pressure is pumped to less than 5×10 -2 Pa, turn on the heater to heat the sample to 250 degrees Celsius, and then pump the pressure of the working chamber to less than 7.0×10 -3 Pa.

[0030] The first stage of high-power pulsed magnetron sputtering was carried out: the power supply used was a high-power pulsed magnetron sputtering power supply, in which the target discharge voltage was 500V, the pulse width was 70μs, the peak current was 150A, the peak voltage was 800V, the substrate negative bias was -850V, the duty cycle was 60%, and high-purity Ar gas was filled to a vacuum degree of 0.5Pa for 20min.

[0031] Then the second stage of high-power pulsed magnetron sputtering was carried out: the sputtering power supply parameters and vacuum degree of the first stage were kept unchanged, the substrate negative bias voltage was adjusted to -120V, the duty cycle was 50%, and the time was 120min.

[0032] The cross-section observation of the deposited tantalum coating shows that the film has a dense structure and is well bonded to the irregular substrate surface, with no shielding holes. The energy spectrum element line scan at the film-substrate interface shows that a 0.5 micron interdiffusion zone appears between the coating and the substrate in the deposited state, indicating that an interfacial metallurgical bond has been formed between the aluminum coating and the N5 substrate.

Claims

1. A sputtering method for forming an interface metallurgical bonding coating, characterized in that: This method uses a high-power pulsed magnetron sputtering process for coating. The deposited coating and the substrate directly diffuse elements to form a metallurgical bond, which greatly improves the bonding strength of the coating and does not require subsequent heat treatment. The sputtering method comprises the following two steps: (1) In the first stage, high-power pulsed magnetron sputtering was used with the following process parameters: target discharge voltage was 400-800 V, pulse width was 30-100 μs, peak current was 100-300 A, peak voltage was 600-1000 V, substrate negative bias voltage was -800--1000 V, duty cycle was 50-60%, high-purity Ar gas was filled to a vacuum degree of 0.2-3 Pa, and the time was 5-120 min; (2) The second stage is high-power pulsed magnetron sputtering, with the following process parameters: target discharge voltage of 400~800V, pulse width of 30~100μs, peak current of 100~300A, peak voltage of 600~1000V, substrate negative bias of -20~-200V, duty cycle of 20~80%, high-purity Ar gas is filled to a vacuum degree of 0.2~0.5Pa, and the time is 30~480min.

2. The sputtering method for forming an interface metallurgical bonding coating according to claim 1, characterized in that: In high-power pulsed magnetron sputtering, the target material used contains one or more elements of Ni, Al, Cr and Ta.

3. The sputtering method for forming an interface metallurgical bonding coating according to claim 1, characterized in that: In high-power pulsed magnetron sputtering, the distance between the target and the substrate is 25~80 mm.

4. The sputtering method for forming an interface metallurgical bonding coating according to claim 1, characterized in that: The high-power pulsed magnetron sputtering is carried out under low temperature conditions, and the deposition temperature is 150-350°C.

5. The sputtering method for forming an interface metallurgical bonding coating according to claim 1, characterized in that: An interface interdiffusion zone with a thickness of more than 0.5 microns is provided between the deposited coating prepared by the method and the substrate.

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