A processing technology for composite chromium plating on the inner bore of a gun barrel

Abstract

The present invention relates to the technical field of chrome plating, and specifically to a processing technology for a composite chromium coating on the inner bore of a gun barrel, which includes the following steps: S1, pretreatment; S2, glow cleaning; S3, first multi-arc ion plating; S4, pulsed etching; S5, second multi-arc ion plating; S6, cooling and discharging. By using the multi-arc ion plating technology to prepare a Cr coating on the surface of the inner bore of the gun barrel, the present invention significantly improves the wear resistance of the inner bore of the gun barrel, effectively reduces the wear during the shooting process, and significantly improves the oxidation resistance of the inner bore of the gun barrel, thereby prolonging the service life of the gun barrel.

Description

Technical Field

[0001] The present invention relates to the technical field of chromium plating, and particularly to a processing technology for a composite chromium coating on the inner bore of a gun barrel. Background Art

[0002] As the core component of a light weapon, due to the service environment of its inner bore being high temperature, high pressure, and strong friction, simply relying on the performance of the gun barrel matrix material itself cannot meet the requirements of its comprehensive performance. Existing technologies often use chromium plating technology to deposit a certain thickness of chromium layer on the inner surface of its inner bore to achieve the purpose of anti-corrosion, wear resistance, and low friction, and ultimately extend the comprehensive life of the light weapon.

[0003] Since the chromium layer is formed inside the gun barrel, it is difficult to control the quality during the treatment of the inner bore of a slender gun barrel using the traditional immersion chromium plating process. This may lead to problems such as significant longitudinal non-uniformity (such as taper difference) of the chromium layer, rough crystal structure, and insufficient surface finish. These factors together reduce the qualification rate of one-time chromium plating of the inner bore of a slender gun barrel. Summary of the Invention

[0004] The purpose of the present invention is to provide a processing technology for a composite chromium coating on the inner bore of a gun barrel to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A processing technology for a composite chromium coating on the inner bore of a gun barrel, including the following steps:

[0006] S1. Pretreatment: First, ultrasonically clean the gun barrel with anhydrous ethanol for 20 - 30 minutes, then wipe the gun barrel with anhydrous ethanol, and finally dry it, repeating 2 times;

[0007] S2. Glow cleaning: First, place the gun barrel in the vacuum chamber of a magnetron sputtering ion coating machine, evacuate to 2.0×10^(-3) Pa, then heat the gun barrel to 300 - 320 °C, and fill the vacuum chamber with argon to 0.3 - 1.0 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the gun barrel and raise it to 900 V within 2 - 3 minutes. Finally, bombard and clean the inner bore of the gun barrel with argon ions for 10 - 20 minutes;

[0008] S3. First multi-arc ion plating: Fill the vacuum chamber with argon to 2 - 5 Pa, apply a negative bias voltage of 300 - 450 V to the inner bore of the gun barrel, apply an arc current of 60 - 90 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the gun barrel along the axis direction, deposit for 20 - 30 minutes, and deposit the first chromium layer on the inner bore of the gun barrel;

[0009] S4. Pulsed etching: Select an ultra-short pulse laser, set the pulse width of the laser to 100 - 300 femtoseconds, and the energy density of the laser to 0.5 - 1.5 J / cm 2, and set the rotation speed of the ultra-short pulse laser to 10 - 30 rpm, and the moving speed of the ultra-short pulse laser along the axis direction to 1 - 5 mm / s. First, control the ultra-short pulse laser to rotate clockwise uniformly along the axis direction into the inner bore of the barrel, and then control the ultra-short pulse laser to rotate clockwise uniformly along the axis direction and exit the inner bore of the barrel;

[0010] S5. Second multi-arc ion plating: Fill the vacuum chamber with argon to 2 - 5 Pa, apply a negative bias voltage of 500 - 900 V to the inner bore of the barrel, apply an arc current of 100 - 120 A to the chromium target, and control the chromium target to enter the inner bore of the barrel uniformly along the axis direction, deposit for 30 - 60 min, and deposit a second chromium layer on the first chromium layer;

[0011] S6. Cooling and taking out of the furnace: First, gradually reduce the negative bias voltage and the arc current, then restore the normal pressure of the vacuum chamber, and take out the barrel after it cools down to room temperature.

[0012] Optionally, the material of the barrel is PCrNi3MoVA.

[0013] Optionally, the thicknesses of the first chromium layer and the second chromium layer are equal, and are both 25 - 50 μm, and the etching depth of the ultra-short pulse laser on the surface of the first chromium layer is 100 - 200 nm.

[0014] Optionally, the etching diameter of the ultra-short pulse laser is 1 - 2 μm, and the laser focal length accuracy of the ultra-short pulse laser is ±0.5 μm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. By using the multi-arc ion plating technology to prepare a Cr coating on the inner bore surface of the barrel, the present invention significantly improves the wear resistance of the inner bore of the barrel, effectively reduces the wear during the shooting process, and significantly improves the oxidation resistance of the inner bore of the barrel, prolongs the service life of the barrel, and the Cr coating effectively isolates the contact between the corrosive medium and the gun steel matrix, reducing the corrosive ions in the residue left in the bore;

[0017] 2. By moving the ultra-short pulse laser into and out of the inner bore of the barrel clockwise along the axis direction, two intersecting spiral etching grooves are etched on the first chromium layer. When the second chromium layer is deposited on the first chromium layer, the spiral etching grooves will be filled. Therefore, the intersecting spiral etching grooves can increase the contact area and bonding strength between the first chromium layer and the second chromium layer. Description of the Drawings

[0018] Figure 1 It is the SEM morphology of Example 4 in Test Example 2;

[0019] Figure 2 It is Figure 1 The SEM morphology of the central region in magnified 2000 times;

[0020] Figure 3 For Figure 2 EDS analysis of area A in Specific implementation manner

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment 1: The present invention provides a process for treating a composite chromium coating on the inner bore of a gun barrel, including the following steps:

[0023] S1. Pretreatment: First, ultrasonically clean the gun barrel with absolute ethanol for 20 min, then wipe the gun barrel with absolute ethanol, and finally dry it, repeating 2 times;

[0024] S2. Glow cleaning: First, place the gun barrel in the vacuum chamber of a magnetron sputtering ion coating machine, evacuate to 2.0×10^(-3) Pa, then heat the gun barrel to 300 °C, and fill the vacuum chamber with argon to 0.3 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the gun barrel and raise it to 900 V within 2 min. Finally, bombard and clean the inner bore of the gun barrel with argon ions for 10 min;

[0025] S3. First multi-arc ion plating: Fill the vacuum chamber with argon to 2 Pa, apply a negative bias voltage of 300 V to the inner bore of the gun barrel, apply an arc current of 60 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the gun barrel along the axial direction, deposit for 20 min, and deposit a first chromium layer with a thickness of 25 μm on the inner bore of the gun barrel;

[0026] S4. Pulsed etching: Select an ultrashort pulse laser, set the pulse width of the laser to 100 femtoseconds, the energy density of the laser to 0.5 J / cm 2 , and set the rotation speed of the ultrashort pulse laser to 10 rpm and the moving speed of the ultrashort pulse laser along the axial direction to 1 mm / s. First, control the ultrashort pulse laser to rotate clockwise uniformly along the axial direction and enter the inner bore of the gun barrel, and then control the ultrashort pulse laser to rotate clockwise uniformly along the axial direction and exit the inner bore of the gun barrel;

[0027] S5. Second multi-arc ion plating: Fill the vacuum chamber with argon to 2 Pa, apply a negative bias voltage of 500 V to the inner bore of the gun barrel, apply an arc current of 100 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the gun barrel along the axial direction, deposit for 30 min, and deposit a second chromium layer with a thickness of 25 μm on the first chromium layer;

[0028] S6. Cooling and taking out: First, gradually reduce the negative bias voltage and arc current, then restore the normal pressure in the vacuum chamber. After the barrel cools down to room temperature, take it out.

[0029] Example 2: The present invention provides a process for treating a composite chromium coating on the inner bore of a barrel, comprising the following steps:

[0030] S1. Pretreatment: First, ultrasonically clean the barrel with anhydrous ethanol for 25 minutes, then wipe the barrel with anhydrous ethanol, and finally dry it, repeating 2 times.

[0031] S2. Glow cleaning: First, place the barrel in the vacuum chamber of a magnetron sputtering ion coating machine, evacuate to 2.0×10^(-3) Pa, then heat the barrel to 310 °C, and fill the vacuum chamber with argon to 0.5 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the barrel and raise it to 900 V within 2 minutes. Finally, bombard and clean the inner bore of the barrel with argon ions for 15 minutes.

[0032] S3. First multi-arc ion plating: Fill the vacuum chamber with argon to 3 Pa, apply a negative bias voltage of 350 V to the inner bore of the barrel, apply an arc current of 70 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axis direction, depositing for 25 minutes to deposit a first chromium layer with a thickness of 30 μm on the inner bore of the barrel.

[0033] S4. Pulsed etching: Select an ultra-short pulse laser, set the pulse width of the laser to 150 femtoseconds, the energy density of the laser to 1.05 J / cm 2 , and set the rotation speed of the ultra-short pulse laser to 25 rpm and the moving speed along the axis direction to 2 mm / s. First, control the ultra-short pulse laser to uniformly rotate clockwise along the axis direction into the inner bore of the barrel, and then control the ultra-short pulse laser to uniformly rotate clockwise along the axis direction and withdraw from the inner bore of the barrel.

[0034] S5. Second multi-arc ion plating: Fill the vacuum chamber with argon to 3 Pa, apply a negative bias voltage of 700 V to the inner bore of the barrel, apply an arc current of 110 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axis direction, depositing for 40 minutes to deposit a second chromium layer with a thickness of 30 μm on the first chromium layer.

[0035] S6. Cooling and taking out: First, gradually reduce the negative bias voltage and arc current, then restore the normal pressure in the vacuum chamber. After the barrel cools down to room temperature, take it out.

[0036] Example 3: The present invention provides a process for treating a composite chromium coating on the inner bore of a barrel, comprising the following steps:

[0037] S1. Pretreatment: First, ultrasonically clean the barrel with anhydrous ethanol for 28 minutes, then wipe the barrel with anhydrous ethanol, and finally dry it, repeating 2 times.

[0038] S2. Glow cleaning: First, place the barrel in the vacuum chamber of a magnetron sputtering ion coating machine, evacuate to 2.0×10^(-3) Pa, then heat the barrel to 315 °C, and fill the vacuum chamber with argon to 0.8 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the barrel, and raise it to 900 V within 3 min. Finally, bombard and clean the inner bore of the barrel with argon ions for 18 min;

[0039] S3. First multi-arc ion plating: Fill the vacuum chamber with argon to 3 Pa, apply a negative bias voltage of 400 V to the inner bore of the barrel, apply an arc current of 80 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axial direction, deposit for 28 min, and deposit a first chromium layer with a thickness of 40 μm on the inner bore of the barrel;

[0040] S4. Pulsed etching: Select an ultra-short pulse laser, set the pulse width of the laser to 200 femtoseconds, the energy density of the laser to 1.2 J / cm 2 , and set the rotation speed of the ultra-short pulse laser to 25 rpm and the moving speed along the axial direction to 4 mm / s. First, control the ultra-short pulse laser to uniformly rotate clockwise along the axial direction into the inner bore of the barrel, and then control the ultra-short pulse laser to uniformly rotate clockwise along the axial direction and exit the inner bore of the barrel;

[0041] S5. Second multi-arc ion plating: Fill the vacuum chamber with argon to 4 Pa, apply a negative bias voltage of 800 V to the inner bore of the barrel, apply an arc current of 115 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axial direction, deposit for 50 min, and deposit a second chromium layer with a thickness of 40 μm on the first chromium layer;

[0042] S6. Cooling and taking out of the furnace: First, gradually reduce the negative bias voltage and arc current, then restore the normal pressure of the vacuum chamber. After the barrel is cooled to room temperature, take it out.

[0043] Example 4: The present invention provides a process for treating a composite chromium coating on the inner bore of a barrel, including the following steps:

[0044] S1. Pretreatment: First, ultrasonically clean the barrel with anhydrous ethanol for 30 min, then wipe the barrel with anhydrous ethanol, and finally dry it, repeating 2 times;

[0045] S2. Glow cleaning: First, place the barrel in the vacuum chamber of a magnetron sputtering ion coating machine, evacuate to 2.0×10^(-3) Pa, then heat the barrel to 320 °C, and fill the vacuum chamber with argon to 0.3 - 1.0 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the barrel, and raise it to 900 V within 3 min. Finally, bombard and clean the inner bore of the barrel with argon ions for 20 min;

[0046] S3. First multi-arc ion plating: Fill the vacuum chamber with argon to 5 Pa, apply a negative bias voltage of 450 V to the inner bore of the barrel, apply an arc current of 90 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axial direction, deposit for 30 min, and deposit a first chromium layer with a thickness of 50 μm on the inner bore of the barrel;

[0047] S4. Pulsed etching: Select an ultrashort pulse laser, set the pulse width of the laser to 300 femtoseconds, the energy density of the laser to 1.5 J / cm 2 , and set the rotation speed of the ultrashort pulse laser to 30 rpm, the moving speed of the ultrashort pulse laser along the axial direction to 5 mm / s. First, control the ultrashort pulse laser to uniformly rotate clockwise along the axial direction into the inner bore of the barrel, and then control the ultrashort pulse laser to uniformly rotate clockwise along the axial direction and exit the inner bore of the barrel;

[0048] S5. Second multi-arc ion plating: Fill the vacuum chamber with argon to 5 Pa, apply a negative bias voltage of 900 V to the inner bore of the barrel, apply an arc current of 120 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the barrel along the axial direction, deposit for 60 min, and deposit a second chromium layer with a thickness of 50 μm on the first chromium layer;

[0049] S6. Cooling and unloading: First, gradually reduce the negative bias voltage and arc current, then restore the normal pressure of the vacuum chamber. After the barrel is cooled to room temperature, take it out.

[0050] In Examples 1 to 4, the material of the barrel is PCrNi3MoVA, and the laser focal length accuracy of the ultrashort pulse laser is ±0.5 μm; in Examples 1 and 2, the etching diameter of the ultrashort pulse laser is 1 μm, and in Examples 3 and 4, the etching diameter of the ultrashort pulse laser is 2 μm.

[0051] Test Example 1

[0052] Test content: Use an HTV-PHS30 high-temperature Vickers hardness tester for hardness testing. During the test, place the main body of the hardness tester in an atmosphere chamber protected by inert gas to prevent the specimen from being oxidized at high temperature. Then, use a high-temperature furnace to heat the specimen to the required temperature and measure the hardness. First, take an unchromed barrel as the control group, place the control group and the barrels obtained in Examples 1 to 4 in the atmosphere chamber, then fill with nitrogen, and then set the temperatures to normal temperature, 300 °C, 500 °C, and 700 °C respectively. Finally, measure the hardness at different temperatures and record the results in Table 1.

[0053] Table 1

[0054]

[0055] As shown in Table 1, the hardness of the barrels obtained in Examples 1 to 4 decreases slowly compared to the barrels without chrome plating, especially at 700°C, the hardness of the barrels obtained in Examples 1 to 4 is much higher than that of the barrels without chrome plating, indicating that the chromium layer of the barrel inner bore obtained in Examples 1 to 4 has good resistance to scratches and wear, and good wear resistance. Therefore, the chromium layer of the barrel obtained in Examples 1 to 4 has good high-temperature mechanical properties and can meet the higher temperature environment of the inner bore. Among them, Example 4 has the highest hardness at various temperatures and is worthy of promotion and use.

[0056] Test Example 2

[0057] Test content: The barrel obtained in Example 4 is made into a gun steel matrix, and a copper rod with the same composition as the ammunition belt is selected as the friction pair. A simulated wear test of the inner wall of the barrel is established by a high-temperature and high-speed friction and wear machine. The reciprocating speed is set to 600r / min, the reciprocating length is 10mm, the loading load is 100N, and the friction time is 20min. Before the experiment, the temperature of the gun steel matrix needs to be heated to 300℃.

[0058] See also Figures 1 to 3 It can be seen that the material at point A is rich in elements O, Cu and Fe, including 2.97% Cu, 40.96% O and 41.60% Fe, which is mainly the oxidation of Fe and Cu. Therefore, the friction surface of the gun steel matrix is mainly dominated by oxidation wear. The Cu element on the surface will be carried away or oxidized under the load pressure, so the copper hanging phenomenon is not obvious. The gun steel matrix has low adhesion to copper, which reduces the formation of copper deposition.

[0059] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A processing technology for composite chromium plating on the inner bore of a gun barrel, characterized in that, It includes the following steps: S1. Pretreatment: First, ultrasonically clean the gun barrel with absolute ethanol for 20 - 30 min, then wipe the gun barrel with absolute ethanol, and finally dry it, repeating 2 times; S2. Glow cleaning: First, place the gun barrel in the vacuum chamber of a magnetron sputtering ion plating machine, evacuate to 2.0×10^(-3) Pa, then heat the gun barrel to 300 - 320 °C, and fill the vacuum chamber with argon to 0.3 - 1.0 Pa. Then apply a negative bias voltage of 500 V to the inner bore of the gun barrel and raise it to 900 V within 2 - 3 min. Finally, bombard and clean the inner bore of the gun barrel with argon ions for 10 - 20 min; S3. First multi - arc ion plating: Fill the vacuum chamber with argon to 2 - 5 Pa, apply a negative bias voltage of 300 - 450 V to the inner bore of the gun barrel, apply an arc current of 60 - 90 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the gun barrel along the axial direction, deposit for 20 - 30 min, and deposit the first chromium layer on the inner bore of the gun barrel; S4, Pulse etching: Select an ultrashort pulse laser, set the pulse width of the laser to 100 - 300 femtoseconds, and the energy density of the laser to 0.5 - 1.5 J / cm 2 , and set the rotation speed of the ultrashort pulse laser to 10 - 30 rpm, and the moving speed of the ultrashort pulse laser along the axial direction to 1 - 5 mm / s. First, control the ultrashort pulse laser to rotate clockwise uniformly along the axial direction and enter the inner bore of the gun barrel, and then control the ultrashort pulse laser to rotate clockwise uniformly along the axial direction and exit the inner bore of the gun barrel; S5. Second multi - arc ion plating: Fill the vacuum chamber with argon to 2 - 5 Pa, apply a negative bias voltage of 500 - 900 V to the inner bore of the gun barrel, apply an arc current of 100 - 120 A to the chromium target, and control the chromium target to uniformly enter the inner bore of the gun barrel along the axial direction, deposit for 30 - 60 min, and deposit the second chromium layer on the first chromium layer; S6. Cooling and taking out of the furnace: First, gradually reduce the negative bias voltage and arc current, then restore the normal pressure of the vacuum chamber. After the gun barrel cools to room temperature, take it out.

2. A processing technology for a composite chromium coating in the inner bore of a gun barrel according to claim 1, characterized in that, The material of the gun barrel is PCrNi3MoVA.

3. A processing technology for a composite chromium coating inside a gun barrel according to claim 1, characterized in that, The thicknesses of the first chromium layer and the second chromium layer are equal, both being 25 - 50 μm, and the etching depth of the ultra - short pulse laser on the surface of the first chromium layer is 100 - 200 nm.

4. A processing technology for composite chromium plating on the inner bore of a gun barrel according to claim 3, characterized in that, The etching diameter of the ultra - short pulse laser is 1 - 2 μm, and the laser focal length accuracy of the ultra - short pulse laser is ±0.5 μm.

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