Method for in-situ plating of high-thickness wear-resistant Cr coating on inner wall of large-diameter artillery barrel and application

Abstract

The invention provides a method for in-situ plating of a high-thickness wear-resistant Cr coating on the inner wall of a large-caliber artillery barrel, and belongs to the technical field of hard coating preparation, the surface of the inner bore of the artillery barrel is plated with the high-thickness wear-resistant Cr coating in situ by adopting a pulse multi-arc ion plating technology, and the high-thickness wear-resistant Cr coating is formed by long-period circulating coating of the Cr coating. Finally, the high-thickness wear-resistant Cr coating is obtained on the inner wall of the large-caliber artillery barrel in situ, the final thickness of the high-thickness wear-resistant Cr coating is 30-50 microns, the prepared wear-resistant Cr coating can improve the film-substrate bonding strength, the performance of the Cr coating is further improved, and the requirement for the performance of an artillery barrel inner cavity in military affairs is met.

Description

Technical Field

[0001] The invention belongs to the technical field of hard coating preparation, and in particular relates to a method and application of in-situ plating of a high-thickness wear-resistant Cr coating on the inner wall of a large-caliber gun barrel. Background Art

[0002] Wear resistance is an important performance evaluation of the surface performance of materials. When parts are worn under certain conditions, their external dimensions will change, and their efficiency will decrease or fail, such as engine blades, the inner bore of artillery barrels, etc. In order to reduce the damage to the inner bore of artillery barrels in modern weapons, improve their ablation resistance and wear resistance, and extend their service life, it is necessary to effectively treat the surface of the material. Common material surface treatment technologies include surface coating, surface modification technology, and thin film technology. The main processes involved are electroplating, painting, surfacing, thermal spraying, thermal diffusion, chemical conversion, vapor deposition, three-beam modification, etc.

[0003] At present, the most representative surface treatment technology is multi-arc ion plating technology, which combines the characteristics of vacuum evaporation and sputtering coating. The coating material is used as the target cathode, and the plasma zone is formed by vacuum arc discharge. The target particles evaporated by the arc discharge move to the plasma zone and then become ionized. The charged target particles are accelerated to the substrate surface under the drive of negative bias voltage and then deposited into a film.

[0004] The high melting point hard film is prepared on the substrate surface using physical vapor deposition technology, which has the advantages of low deposition temperature, fast deposition efficiency, and dense structure. However, due to the large differences in hardness, modulus, thermal expansion coefficient, etc. between the hard film and the alloy, the film has low bearing capacity and is prone to cracking or even delamination failure under high temperature and high load.

[0005] Practice shows that the multi-arc ion plating Cr on the substrate has the characteristics of high hardness, strong wear resistance, excellent ablation resistance and corrosion resistance, and is currently the most common anti-ablation coating for the inner wall of the barrel. However, the microcracks of the Cr coating will seriously damage the interface between the coating and the substrate, and finally cause the coating to fall off. Summary of the invention

[0006] In view of the problems existing in the prior art such as poor bonding strength between the coating and the substrate, easy cracking of the coating, mismatch between the target material and the substrate plating, the present invention provides a method and application of in-situ plating of a high-thickness wear-resistant Cr coating on the inner wall of a large-caliber artillery barrel. The wear-resistant Cr coating prepared by the present invention can improve the film-base bonding strength and further improve the performance of the Cr coating to meet the military requirements for the performance of the inner bore of the artillery barrel.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for in-situ coating of a high-thickness wear-resistant Cr coating on the inner wall of a large-caliber gun barrel, using a pulse multi-arc ion plating technology to coat a high-thickness wear-resistant Cr coating on the inner surface of the gun barrel, and finally obtaining a high-thickness wear-resistant Cr coating by cyclically coating the Cr coating over a long period of time, wherein the final thickness of the high-thickness wear-resistant Cr coating is 30-50 μm.

[0009] Furthermore, the method for coating the inner wall of the gun barrel with a high-thickness wear-resistant Cr coating comprises the following steps:

[0010] (1) First, the inner and outer surfaces of the gun barrel are degreased, followed by ultrasonic cleaning. The cleaned gun barrel is cleaned with alcohol, blown dry with nitrogen, and placed on the rotating rack of the vacuum chamber of the coating equipment. The vacuum chamber is evacuated to a vacuum degree of less than 5×10 -4 Pa, while heating to 100-300℃;

[0011] (2) Next, the inner bore of the gun barrel in step (1) is cleaned by argon ion glow in a coating device, and after the cleaning is completed, a workpiece to be plated is obtained;

[0012] (3) using a multi-arc ion plating technique to act on a columnar cathode Cr target placed inside a gun barrel to deposit a transition layer on the workpiece to be plated in step (2) to obtain a workpiece containing a transition layer;

[0013] (4) The workpiece containing the transition layer obtained in step (3) is coated with a pure Cr coating for a long time by using pulse enhanced multi-arc ion plating technology, and finally a high-thickness wear-resistant Cr coating is obtained.

[0014] In view of the problems of thinness, brittleness, low bearing capacity and mismatch of thermal expansion coefficient of Cr coating hard film, the following two ideas are proposed: First, whether a transition layer can be pre-plated before formal plating so that the coating can be tightly combined with the substrate; second, the coating is prone to cracking and falling off when the thickness is small. If a high-thickness coating is prepared by a long-term deposition method, can the problem of coating cracking be reduced or even solved while greatly improving the wear resistance. In addition, how to evenly deposit the coating on the inner wall of a large-caliber and long-sized artillery barrel? Obviously, ordinary flat targets are difficult to meet the requirements, and special targets need to be developed to match them. Based on the above ideas, an effective solution was obtained through research, thus forming the present invention.

[0015] Furthermore, the specific method of step (2) is as follows: first, introduce argon gas into the vacuum chamber of the coating equipment, adjust the air flow rate through a flow meter, maintain the air pressure in the vacuum chamber at 0.5-3.0Pa, then turn on the bias power supply, adjust the bias value to 200V-1200V, the duty cycle to 30-80%, the turntable rotation speed to 1.0-3.0r / min, and perform argon glow cleaning for 50-150min to finally obtain the workpiece to be plated.

[0016] Furthermore, the specific method of step (3) is as follows: turn on the pulse multi-arc power supply, apply Cr transition coating to the inner surface of the gun barrel, firstly introduce N into the vacuum chamber. 2 Then, turn off the Ar gas, maintain the pressure in the vacuum chamber at 0.5-3.0 Pa, adjust the bias value to 20-45 V, keep the rotating speed unchanged, and finally deposit the transition layer CrN layer for 30-100 min.

[0017] Furthermore, the specific method of step (4) is as follows: turn on the power supply of the pulse multi-arc, fill the coating chamber with argon gas, and make its pressure reach (1-5)×10 -1 Pa, target current is set to 15-60A, barrel negative bias is 30-100V, pulse frequency is 15-60KHz, pulse duty cycle is 30%-80%, coating deposition time is 30-80min. In order to obtain high thickness wear-resistant Cr coating, pause for 1-5min after this step, and then perform this step, and repeat the deposition cycle for 10-50 times.

[0018] The present invention also provides an application of a high-thickness wear-resistant Cr coating obtained according to the above method in reducing damage to the inner bore of a gun barrel.

[0019] An application of the high-thickness wear-resistant Cr coating obtained according to the above method in the preparation of artillery.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] (1) The method of the present invention is used to firstly perform Ar ion glow cleaning on the gun barrel in the vacuum chamber of the coating equipment, then deposit a thin transition layer CrN layer thereon, and finally cyclically coat the pure Cr coating on the transition layer, and finally a high-thickness coating is deposited on the inner bore surface of the barrel. Since the hardness of the transition layer CrN layer is relatively low, it is beneficial to improve the bonding between the coating and the substrate. The high-thickness hard Cr coating finally deposited has greatly improved its ablation resistance and wear resistance, and has a great effect on extending the life of the gun barrel;

[0022] (2) The present invention changes the cyclic deposition time during the coating of the pure Cr coating, thereby changing the thickness of the coating, and further adjusting the microstructure and microhardness of the coating, so as to adapt to the barrel performance under different military conditions;

[0023] (3) The preparation process of the present invention is simple and easy to control, and has the advantages of high deposition rate and low cost. A prefabricated cylindrical cathode pure chromium target of a specific size is placed inside the barrel, so that the maximum area of ​​the barrel can be plated, and the coating is uniform and dense. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 Energy spectrum analysis diagram of the pure chromium target used in Example 1 and Example 2;

[0026] Figure 2 This is a cross-sectional morphology of the high-thickness wear-resistant Cr coating prepared in Example 1;

[0027] Figure 3 The low-magnification morphology (left) and high-magnification morphology (right) of the coating obtained in Example 1 after laser ablation;

[0028] Figure 4 This is the element spectrum analysis diagram of the coating obtained in Example 1 after laser ablation;

[0029] Figure 5 The low-magnification morphology (left) and high-magnification morphology (right) of the coating obtained in Example 1 after friction and wear;

[0030] Figure 6 This is the element spectrum analysis diagram of the coating obtained in Example 1 after friction and wear;

[0031] Figure 7 This is a cross-sectional morphology of the high-thickness wear-resistant Cr coating prepared in Example 2;

[0032] Figure 8 The low-magnification morphology (left) and high-magnification morphology (right) of the coating obtained in Example 2 after laser ablation;

[0033] Fig. 9 This is the element spectrum analysis diagram of the coating obtained in Example 2 after laser ablation;

[0034] Fig.10 The SEM surface low-magnification morphology (left) and high-magnification morphology (right) of the coating after friction and wear in Example 2;

[0035] Fig.11 This is the elemental energy spectrum analysis diagram of the coating in Example 2 after friction and wear. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0038] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0039] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0040] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0041] All raw materials used in the examples of the present invention are purchased from the market. The energy spectrum analysis diagram of the pure chromium target used in Examples 1 and 2 is shown in FIG. Figure 1 shown.

[0042] The technical solution of the present invention is further illustrated by the following embodiments.

[0043] Example 1

[0044] (1) First, the inner and outer surfaces of the gun barrel are degreased, followed by ultrasonic cleaning. The cleaned gun barrel is cleaned with alcohol, blown dry with nitrogen, and placed on the rotating rack of the vacuum chamber of the coating equipment. The vacuum chamber is evacuated to a vacuum degree of less than 5×10 -4 Pa, and at the same time the temperature was raised to 200°C;

[0045] (2) First, argon gas is introduced into the vacuum chamber of the coating equipment, and the inlet flow rate is adjusted by a flow meter to maintain the air pressure in the vacuum chamber at 2.0 Pa. Then, the bias power supply is turned on, the bias value is adjusted to 700 V, the duty cycle is 50%, the rotating frame rotation speed is 2.0 r / min, and the argon glow cleaning time is 100 min to obtain the workpiece to be plated;

[0046] (3) A multi-arc ion plating technique is used to act on a columnar cathode Cr target placed inside a gun barrel, and a transition layer is deposited on the workpiece to be plated in step (2) to obtain a workpiece containing a transition layer. The specific steps are as follows: Turn on a pulsed multi-arc power supply, and coat the inner surface of the gun barrel with a Cr transition coating. First, N is introduced into the vacuum chamber. 2 Then, the Ar gas was turned off, the pressure in the vacuum chamber was maintained at 2.0 Pa, the bias value was adjusted to 30 V, the rotating speed of the rotating frame was kept unchanged, and finally the transition layer CrN layer was deposited for 60 min;

[0047] (4) The workpiece containing the transition layer obtained in step (3) is coated with a pure Cr coating for a long time by using pulse enhanced multi-arc ion plating technology, and finally a high-thickness wear-resistant Cr coating is obtained. The specific steps are as follows: Turn on the power supply of the pulse multi-arc, fill the coating chamber with argon gas, and make its pressure reach 3×10 -1 Pa, the target current is set to 30A, the negative bias voltage of the barrel is 60V, the pulse frequency is 30KHz, the pulse duty cycle is 50%, and the coating deposition time is 60min. In order to obtain a high-thickness wear-resistant Cr coating, this step is paused for 3min after the end, and then this step is performed again. The deposition is repeated 30 times, and the final thickness of the high-thickness wear-resistant Cr coating is 37.83μm.

[0048] In this embodiment, N is adjusted during the deposition process. 2 The flow rate or pressure can obtain nitride transition coatings with different phase compositions, laying the foundation for the subsequent deposition of high-thickness wear-resistant coatings. Figure 2 As shown, in this embodiment, a transition layer CrN layer is first deposited on the surface of the gun steel to better generate a pure chromium coating. The thickness of the transition coating is 4.59 μm, the thickness of the pure chromium coating is 33.24 μm, and the total thickness of the coating is 37.83 μm. In general, there are no holes or cracks inside the coating, and the structure is dense.

[0049] In this embodiment, when performing laser ablation experiments on coatings, long pulse width lasers are used for the experiments. The specific parameters of the ablation experiments are: wavelength 1064nm, pulse width 10ns, frequency 10Hz, single energy 1500mJ, and pulse peak power 9MW. The substrate is polished before the experiment, the instrument is preheated before the experiment, and then the sample is placed 30cm away from the laser transmitter, and a steel plate is placed behind the sample to prevent the laser from reflecting to other places and accidentally injuring the experimenter.

[0050] Figure 3 The low-magnification and high-magnification morphology after laser ablation obtained in Example 1. It can be seen that after laser ablation, there are obvious irregular circular traces on the coating surface, pits appear, and traces of scattering gradually changing outward appear on the outer circle of the circle. After the scanning electron microscope is magnified 2000 times, it can be clearly seen that there are cracks of varying thickness at the ablation pits. After energy spectrum analysis, it can be seen that oxides appear at almost every intersection of cracks. The elemental composition spectrum of the high-thickness wear-resistant Cr coating is shown in the figure below. Figure 4 shown.

[0051] The wear resistance of the sample in the embodiment was tested using a HSR-2M high-speed reciprocating friction and wear tester. The grinding ball was a 304 stainless steel ball with a diameter of φ9.525mm; the applied pressures were 3N, 6N, and 9N respectively; the sliding frequency was 2Hz; the sliding length was 5mm; the sliding rate was 24mm / s; the running time was 20min; and the normal temperature test temperature was 25°C. Multiple friction and wear experiments were carried out on the high-thickness wear-resistant Cr coating to eliminate accidental factors. The SEM surface morphology after the friction and wear with an applied pressure of 6N is selected as follows Figure 5 As shown in the figure, it can be seen that the friction marks of the coating are relatively shallow, the bumps are not obvious, and generally only a straight line of wear marks can be observed. When the coating surface is magnified 2000 times, Figure 5 As shown in the figure, only small protrusions were observed at the wear marks, and there were no deep groove wear marks. The element spectrum analysis of the coating after friction and wear was performed, and the results were as follows: Figure 6 As shown in the figure, the main elements of the coating are C, N, O, Cr, and Fe. In addition, there is also metallic Ni in the pure Cr coating.

[0052] Example 2

[0053] (1) First, the inner and outer surfaces of the gun barrel are degreased, followed by ultrasonic cleaning. The cleaned gun barrel is cleaned with alcohol, blown dry with nitrogen, and placed on the rotating rack of the vacuum chamber of the coating equipment. The vacuum chamber is evacuated to a vacuum degree of less than 5×10 -4 Pa, and at the same time the temperature was raised to 200°C;

[0054] (2) First, argon gas is introduced into the vacuum chamber of the coating equipment, and the inlet flow rate is adjusted by a flow meter to maintain the pressure in the vacuum chamber at 2.0 Pa. Then, the bias power supply is turned on, the bias value is adjusted to 800 V, the duty cycle is 50%, the rotating frame rotation speed is 2.5 r / min, and the argon glow cleaning time is 150 min to obtain the workpiece to be plated;

[0055] (3) The multi-arc ion plating technology is used to act on the columnar cathode Cr target placed inside the gun barrel, and the workpiece to be plated in step (2) is coated with a pure Cr coating for a long time, and finally a high-thickness wear-resistant Cr coating without a transition layer is obtained. The specific steps are as follows: Turn on the pulse multi-arc power supply, fill argon gas into the coating chamber, and make its pressure reach 3×10 -1 Pa, the target current is set to 25A, the negative bias voltage of the barrel is 50V, the pulse frequency is 25KHz, the pulse duty cycle is 50%, and the coating deposition time is 40min. In order to obtain a high-thickness wear-resistant Cr coating, this step is paused for 5min after the end, and then this step is performed again. The deposition is repeated 20 times, and the final thickness of the high-thickness wear-resistant Cr coating is 28.43μm.

[0056] like Figure 7 As shown, the high-thickness wear-resistant Cr coating prepared in this embodiment has a thickness of 28.43 μm, the coating is dense and uniform, has no holes or cracks inside, and has a uniform and flat structure.

[0057] This embodiment adopts the same laser ablation method as that of embodiment 1. Figure 8 The following are the low-magnification and high-magnification morphology of the high-thickness wear-resistant Cr coating after laser ablation. It can be seen that after laser ablation, obvious ablation pits appear on the surface of the coating, and there are traces of scattering gradually changing outward. After the morphology is magnified, it can be observed that there are large cracks of varying lengths at the ablation pits, accompanied by the generation of black spot-like substances. After energy spectrum analysis, it can be seen that the black substances are all oxidation products after ablation. The element energy spectrum analysis diagram of the coating after laser ablation is shown in Figure 1. Fig. 9 shown.

[0058] In this embodiment, after the high-speed reciprocating friction and wear test, the SEM surface morphology after the friction and wear with a pressure of 6N is selected as follows: Fig.10 As shown in the figure, it can be seen that the friction marks of the coating are in the shape of typical gullies, accompanied by irregular protrusions, and the wear marks are generally shallow. After the coating surface is enlarged, the element spectrum analysis diagram is as follows Fig.11 As shown in the figure, more obvious groove-like friction marks appeared, and there were white deposits on the edges of the grooves, which may be the result of the accumulation of friction particles. Fig.11 As shown, from the atlas data, it can be seen that the main elements of the coating are C, N, O, Cr, Fe, and Ni.

[0059] Comparative Example 1

[0060] The same as Example 1, the only difference is that the transition layer is not deposited, and the pure Cr coating is directly coated on the workpiece to be plated. Due to the reduction of deposition time, the thickness of the coating is reduced, and the cross-sectional morphology of the coating is dense and uniform. Due to the reduction of coating thickness and the absence of transition layer, the wear resistance of the coating is reduced, and the surface morphology after friction and wear is greatly different, becoming a deep groove type wear mark. It can be seen that the increase in the thickness of the deposited coating is conducive to the improvement of wear resistance.

[0061] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for in-situ coating of a high-thickness wear-resistant Cr coating on the inner wall of a large-caliber gun barrel, characterized in that: A high-thickness wear-resistant Cr coating is plated on the inner surface of the gun barrel by pulse multi-arc ion plating technology. The Cr coating is cyclically coated over a long period of time to finally obtain a high-thickness wear-resistant Cr coating, wherein the final thickness of the high-thickness wear-resistant Cr coating is 30-50 μm.

2. The method for coating the inner wall of a gun barrel with a high-thickness wear-resistant Cr coating according to claim 1, characterized in that: The following steps are involved: (1) First, the inner and outer surfaces of the large-caliber gun barrel are degreased, followed by ultrasonic cleaning. The cleaned gun barrel is cleaned with alcohol, blown dry with nitrogen, and placed on the rotating rack of the vacuum chamber of the coating equipment. The vacuum chamber is evacuated to a vacuum degree of less than 5×10 -4 Pa, while heating to 100-300℃; (2) Next, the inner bore of the gun barrel in step (1) is cleaned by argon ion glow in a coating device, and after the cleaning is completed, a workpiece to be plated is obtained; (3) using a multi-arc ion plating technique to act on a columnar cathode Cr target placed inside a gun barrel to deposit a transition layer on the workpiece to be plated in step (2) to obtain a workpiece containing a transition layer; (4) The workpiece containing the transition layer obtained in step (3) is coated with a pure Cr coating for a long time by using pulse enhanced multi-arc ion plating technology, and finally a high-thickness wear-resistant Cr coating is obtained.

3. The method for coating the inner wall of a large-caliber gun barrel with a high-thickness wear-resistant Cr coating according to claim 2, characterized in that: The specific method of step (2) is as follows: first, introduce argon gas into the vacuum chamber of the coating equipment, adjust the air flow rate through a flow meter, maintain the air pressure in the vacuum chamber at 0.5-3.0 Pa, then turn on the bias power supply, adjust the bias value to 200V-1200V, the duty cycle to 30-80%, the turntable rotation speed to 1.0-3.0r / min, and perform argon glow cleaning for 50-150min to finally obtain the workpiece to be plated.

4. The method for coating the inner wall of a gun barrel with a high-thickness wear-resistant Cr coating according to claim 2, characterized in that: The specific method of step (3) is as follows: turn on the pulse multi-arc power supply, apply Cr transition coating to the inner surface of the gun barrel, first introduce N2 into the vacuum chamber, then turn off the Ar gas, maintain the air pressure in the vacuum chamber at 0.5-3.0Pa, adjust the bias value to 20-45V, keep the rotating speed unchanged, and finally deposit the transition layer CrN layer for 30-100min.

5. The method for coating the inner wall of a gun barrel with a high-thickness wear-resistant Cr coating according to claim 2, characterized in that: The specific method of step (4) is as follows: turn on the power supply of the pulse multi-arc, fill the coating chamber with argon gas, and make its pressure reach (1-5)×10 -1 Pa, target current is set to 15-60A, barrel negative bias is 30-100V, pulse frequency is 15-60KHz, pulse duty cycle is 30%-80%, coating deposition time is 30-80min, pause for 1-5min after this step, then perform this step again, and repeat the deposition cycle for 10-50 times.

6. Use of a high-thickness wear-resistant Cr coating obtained by the method according to any one of claims 1 to 5 in reducing damage to the inner bore of a gun barrel.

7. Use of a high-thickness wear-resistant Cr coating obtained by the method according to any one of claims 1 to 5 in the preparation of artillery.

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