Spraying method and preparation method of steel surface coating electrolyte based on artillery tube body

Abstract

The invention belongs to a metal surface treatment strengthening technology, and discloses a spraying method and a preparation method of a steel surface coating electrolyte based on an artillery barrel body, and the spraying method comprises the following steps: putting a pretreated artillery barrel into the prepared electrolyte by steel, carrying out micro-arc oxidation treatment, applying high voltage in the electrolyte to generate micro-arc discharge, and carrying out surface treatment on the artillery barrel body. The surface of the gun steel is locally melted and rapidly cooled, and a compact ceramic layer film is generated on the surface of the gun steel; and subsequently, carrying out hole sealing treatment on the film layer by additionally adding nano-particles, so as to improve the surface appearance of the film layer. According to the spraying method and the preparation method of the steel surface coating electrolyte based on the artillery tube body, key parameters such as current density, voltage, electrolyte components and temperature in the micro-arc oxidation process need to be monitored in real time in the process, after micro-arc oxidation treatment, the hardness, wear resistance, high-temperature performance and the like of artillery steel are improved to a certain extent, and due to improvement of the performance, the service life of the artillery tube body is greatly prolonged. And the service life of the gun steel serving as the gun barrel can be remarkably prolonged.

Description

Technical Field

[0001] The invention belongs to the field of surface treatment of metal materials, namely a method for preparing a ceramic layer film on a steel surface through micro-arc oxidation technology. Background Art

[0002] Since its birth, artillery has been an important weapon in war, and people have continuously improved its performance in order to project heavier shells to farther places on various battlefields. In modern warfare, artillery is more and more required to meet the requirements of long range, strong firepower and high precision, which requires artillery shells to have higher initial velocity and kinetic energy. Therefore, the amount of propellant in the shells is increasing, and the shells are getting heavier. The military's performance requirements for artillery equipment are also constantly improving. Modern artillery also shows a development trend of high power, high chamber pressure, high initial velocity and high overload.

[0003] As an important part of the artillery, the gun barrel is responsible for rotating the shells and launching them at high speed around the target. The working environment of the gun barrel is very harsh. During the artillery firing process, the inner wall of the barrel is not only subjected to the high-temperature, high-pressure, high-speed gunpowder gas and various microparticles, but also to the high-speed friction of the outer side of the shell along the rifling, which causes serious ablation and wear on the inner wall of the gun barrel, seriously affecting the performance of the artillery and causing the service life of the gun barrel to be sharply reduced. Specifically, the factors that affect the gun barrel are thermal, chemical, and mechanical factors.

[0004] The steel used for gun barrels has high hardness and good wear resistance, but its performance at high temperatures is relatively average. In order to further improve its performance to meet the use requirements, it can be surface modified to form a film with higher hardness, stronger wear resistance and better high temperature performance to protect the gun barrel. At present, the commonly used modification methods for gun barrels include electroplating, magnetron sputtering, thermal cladding, spraying, etc., but each method has more or less problems.

[0005] Micro-arc oxidation (MAO) technology is a green and environmentally friendly surface processing technology that can directly generate a ceramic film layer on the metal surface in situ. The film layer has high hardness, wear resistance, corrosion resistance and other properties, which are exactly the properties required for artillery barrel steel. If this technology is successfully used to process artillery barrel steel, its hardness, wear resistance and other properties can be improved, and the service life of the artillery barrel can be extended.

[0006] However, micro-arc oxidation technology is generally used to treat valve metals such as Al, Mg, and Ti. There is relatively little research on non-valve metals such as steel. There are many challenges in preparing micro-arc oxidation films on steel surfaces, including how to accurately control the electrolyte conditions and electrical parameter processes during micro-arc oxidation to obtain an ideal ceramic layer, and what kind of nanoparticles to use in the sealing treatment. In order to produce micro-arc oxidation ceramic layers with high hardness, tight bonding, good wear resistance and high temperature performance on the surface of artillery steel, scholars in the field of materials science need to continue their research. Summary of the invention

[0007] The object of the present invention is to provide a method for spraying an electrolyte for a steel surface coating on a gun barrel and a method for preparing the electrolyte. To achieve the above object, the present invention adopts the following technical solutions:

[0008] The method for spraying an electrolyte coating on a steel surface of a gun barrel is characterized by comprising the following steps:

[0009] The pre-treated gun barrel steel is placed in a prepared electrolyte for micro-arc oxidation treatment. A high voltage is applied in the electrolyte to generate a tiny arc discharge, so that the surface of the gun steel is partially melted and rapidly cooled, forming a dense ceramic layer on the surface;

[0010] Then, the membrane layer is sealed by adding nanoparticles to improve the surface morphology of the membrane layer. During the process, key parameters such as current density, voltage, electrolyte composition and temperature during micro-arc oxidation need to be monitored in real time.

[0011] Furthermore, the prepared micro-arc oxidation electrolyte comprises electrolyte raw materials of the following concentrations:

[0012] Sodium aluminate (NaAlO 2 )15g / L;

[0013] Sodium dihydrogen phosphate (NaH 2 PO 4 )3g / L;

[0014] Sodium carbonate (Na 2 CO 3 )3g / L;

[0015] Sodium tetraborate (Na 2 B 4 O 7 )3g / L;

[0016] Alumina nanoparticles (α-Al 2 O 3 )3g / L;

[0017] The rest are deionized water;

[0018] 5 mL / L of glycerol is also added to the electrolyte. Glycerol does not participate in the micro-arc oxidation reaction. Its specific function is to slow down the evaporation of the electrolyte by the arc generated by the high voltage.

[0019] Furthermore, the prepared micro-arc oxidation electrolyte comprises electrolyte raw materials of the following concentrations:

[0020] Sodium aluminate (NaAlO 2 )15g / L;

[0021] Sodium dihydrogen phosphate (NaH 2 PO 4 )3g / L;

[0022] Sodium carbonate (Na 2 CO 3 )3g / L;

[0023] Sodium tetraborate (Na 2 B 4 O 7 )3g / L;

[0024] The rest are deionized water;

[0025] Similarly, 5 mL / L of glycerol is also added to the electrolyte. Glycerol does not participate in the micro-arc oxidation reaction, and its specific function is to slow down the evaporation of the electrolyte by the arc generated by the high voltage. In addition, the added α-Al 2 O 3 The particle size of the nanoparticles is 30 nanometers.

[0026] Further, the specific steps of micro-arc oxidation treatment are:

[0027] Step 1, pretreatment of the substrate: the substrate is cut into small rectangular blocks and punched, then polished to remove the residual polishing particles on the surface, then placed in anhydrous ethanol for ultrasonic cleaning to remove surface impurities and oil stains, and then the sample is vacuum dried and waits for use;

[0028] Step 2, preparation and adjustment of electrolyte: weigh calculated amounts of sodium aluminate, sodium dihydrogen phosphate, sodium carbonate, and sodium tetraborate and dissolve them in deionized water, and add glycerol to the prepared electrolyte, and control the temperature between room temperature and 40°C;

[0029] Step 3, equipment adjustment: hang the gun steel with iron wire in the micro-arc oxidation equipment, suspend it in the electrolyte, do not touch the bottom, turn on the cooling water circulation and stirring device, the gun steel substrate is used as the anode, and the inner tank of the micro-arc oxidation machine is used as the cathode to form an electrolytic cell;

[0030] Step 4, electrical parameter setting and monitoring: set the positive and negative voltage, pulse frequency, positive and negative duty cycle and other parameters. During the reaction process of micro-arc oxidation, monitor the voltage, current density, electrolyte temperature and other key parameters in real time, and find the appropriate electrical parameters so that the arc can maintain the discharge state, ensuring the uniform occurrence of local melting and rapid cooling process;

[0031] Step 5, oxidation time and film quality control: set different oxidation times, test the film forming quality of the sample, and select the appropriate oxidation time;

[0032] Step 6, post-processing and preliminary testing: After the micro-arc oxidation reaction is completed, the sample is taken out, rinsed with water to remove the residual electrolyte on the surface, and then dried.

[0033] Further, the parameter settings in step 4 are as follows:

[0034] After multiple groups of micro-arc oxidation experiments using the controlled variable method, suitable electrical parameters were obtained as follows: a forward voltage of 550 V, a negative voltage of -50 V, a pulse frequency of 800 Hz, and a positive and negative duty cycle of 20%.

[0035] Further, the parameter monitoring in step 4 specifically includes:

[0036] Voltage management and control: After multiple sets of micro-arc oxidation experiments at different voltages, the appropriate voltage is obtained. The voltage is set before the micro-arc oxidation experiment, and the power management system is used to monitor the voltage fluctuation during the reaction in real time, from 0V at the beginning of the reaction to the voltage of 550V required for the reaction, and during the reaction after reaching 550V, if the voltage exceeds the set voltage by ±5%, the power system will adjust the power supply strategy in real time to make the voltage normal, avoid local overheating or uneven oxidation, so as not to affect the molding quality of the film layer;

[0037] Management and control of current density: After multiple sets of micro-arc oxidation experiments, the appropriate current density range is obtained. During the micro-arc oxidation reaction, the current density during the reaction can be monitored in real time through the power management system. If the current density exceeds the preset value, the power management system will automatically adjust the current density. If the current is abnormal, the system will automatically cut off the power to protect the machine.

[0038] Temperature control and adaptation: Place a temperature measurement sensor in the electrolyte to observe the current temperature of the electrolyte in real time;

[0039] Data recording and analysis: During the oxidation process, various key parameters, including voltage changes, current density, electrolyte temperature, etc., will be recorded for reference in subsequent experiments.

[0040] Further, the oxidation time of step 5 is adjusted as follows:

[0041] After determining the appropriate electrical parameters, several groups of different oxidation times were selected for experiments, ranging from 10 minutes to 30 minutes. After the oxidation was completed, the samples were taken out and the film layers of the samples were preliminarily tested, mainly focusing on basic characteristics such as film forming quality and surface morphology. A group of samples with relatively complete film layers were selected to determine the appropriate oxidation time.

[0042] Further, the preliminary detection of step 6 specifically includes:

[0043] X-ray diffraction analysis: Cut the prepared film samples into small pieces and put them into X-ray diffractometer for phase analysis. Cu target was used, tube voltage was 40kV, and tube current was 30mA. The diffraction angle range was 20-80°, and the scanning speed was 2° / min. MDI Jade analysis software was used to analyze the XRD test results to confirm the phase composition of the film layer;

[0044] Surface morphology of the film layer: Use a scanning electron microscope to photograph the surface of the sample film layer and observe its surface morphology, such as pore size, pore distribution, roughness, etc.

[0045] Film thickness test: Use a coating thickness gauge to measure the thickness of the sample film layer, and zero adjustment is required before the experiment. During the measurement, multiple measurements are made at different locations of each sample, and the average thickness of each film layer sample is obtained through processing;

[0046] Film hardness test: Use a microhardness tester to measure the hardness of the film sample surface. Select 12 points from different positions on the sample surface, subtract the maximum value and calculate the average value to obtain the average hardness of the film layer.

[0047] Film adhesion test: The adhesion of the film sample is tested using an automatic coating adhesion scratch tester. After the test, an acoustic signal image is generated to observe the load at which the film is scratched, and the scratches on the film surface are observed with an optical microscope to confirm whether the position where the film is completely scratched is consistent with the reading of the automatic coating adhesion scratch tester.

[0048] Further, the specific steps of micro-arc oxidation sealing treatment are:

[0049] Step 1, pretreatment of the substrate: the substrate is cut into small rectangular blocks and punched, then polished to remove the residual polishing particles on the surface, then placed in anhydrous ethanol for ultrasonic cleaning to remove surface impurities and oil stains, and then the sample is vacuum dried and waits for use;

[0050] Step 2, preparation and adjustment of electrolyte: weigh calculated amounts of sodium aluminate, sodium dihydrogen phosphate, sodium carbonate, sodium tetraborate and additional alumina nanoparticles and dissolve them in deionized water, and add glycerol to the prepared electrolyte, and control the temperature between room temperature and 40°C;

[0051] Step 3, equipment adjustment: hang the gun steel with iron wire in the micro-arc oxidation equipment, suspend it in the electrolyte, do not touch the bottom, turn on the cooling water circulation and stirring device, the gun steel substrate is used as the anode, and the inner tank of the micro-arc oxidation machine is used as the cathode to form an electrolytic cell;

[0052] Step 4, electrical parameter setting and monitoring: set the positive and negative voltage, pulse frequency, positive and negative duty cycle and other parameters. During the reaction process of micro-arc oxidation, monitor the voltage, current density, electrolyte temperature and other key parameters in real time, and find the appropriate electrical parameters so that the arc can maintain the discharge state, ensuring the uniform occurrence of local melting and rapid cooling process;

[0053] Step 5, oxidation time and film quality control: set different oxidation times, test the film forming quality and related properties of the sample, and select the appropriate oxidation time;

[0054] Step 6, post-processing and performance testing: After the micro-arc oxidation reaction is completed, the sample is taken out, rinsed with water to remove the residual electrolyte on the surface, and then dried and waited for relevant performance tests.

[0055] Further, the electrolyte configuration in step 2 is as follows:

[0056] After completing the micro-arc oxidation treatment on the gun steel and conducting relevant performance tests, a more suitable electrolyte composition (the content of sodium aluminate, sodium dihydrogen phosphate, sodium carbonate and sodium tetraborate) was obtained. Different contents of α-Al 2 O 3 Nanoparticles, multiple groups of electrolytes with different nanoparticle concentrations were configured for experiments.

[0057] Furthermore, the performance test of step 6 specifically includes:

[0058] The relevant properties in the preliminary test include: X-ray diffraction analysis of the film layer, surface morphology of the film layer, thickness of the film layer, microhardness of the film layer, bonding strength between the film layer and the substrate, etc.

[0059] Surface element distribution of the film layer: The surface of the sample film layer was photographed using a scanning electron microscope, and the element composition of the film layer was analyzed using an energy dispersive spectrometer (EDS) attached to the SEM;

[0060] Cross-sectional morphology and element distribution of the film layer: The cross-sectional area of ​​the sample film layer was photographed using a scanning electron microscope to observe the morphology and thickness of the dense layer and loose layer of the micro-arc oxidation film layer, and the element composition of the film layer was analyzed using the energy dispersive spectrometer (EDS) attached to the SEM to study the added α-Al 2 O 3 Whether the nanoparticles have entered the interior of the pores;

[0061] High temperature friction and wear test of the film layer: The friction and wear resistance of the film layer sample under high temperature conditions is tested using a high temperature friction and wear tester. 3 N 4 The ball and the sample film surface were subjected to a grinding test. After the test, the friction coefficient was recorded, and the wear scar depth and width were measured with a three-dimensional profilometer. The microscopic morphology of the wear scar was photographed with a scanning electron microscope, the friction mechanism was analyzed, and the mass wear rate was calculated by the wear mass to evaluate the high-temperature wear resistance of the sample film layer.

[0062] Film ablation resistance test: Use an oxygen-ethane flame spray gun to test the ablation resistance of the film sample under high-temperature flame scouring. The nozzle is ablated at 90° to the sample surface. Record the mass change before and after ablation, and calculate the mass ablation rate to evaluate the ablation resistance of the sample film layer.

[0063] Thermal shock resistance test of the film layer: The thermal shock resistance of the film layer is tested by using the cyclic heating-quenching cooling method. The sample is placed in a muffle furnace, heated to the set temperature and kept warm. Then it is taken out for quenching and rapid cooling. The surface morphology of the film layer is observed to see if the film layer is damaged or cracked, so as to evaluate the thermal shock resistance of the sample film layer.

[0064] The beneficial effects of the present invention are as follows:

[0065] 1. Improved material performance: After micro-arc oxidation treatment, the hardness, wear resistance, and high temperature performance of the gun steel are all improved to a certain extent. These performance improvements can significantly increase the service life of the gun steel as a gun barrel;

[0066] 2. Research on micro-arc oxidation of non-valve metals: Micro-arc oxidation technology is limited by the technology itself and is generally used for valve metals such as Al, Mg, and Ti. The present invention studies the performance of the ceramic layer film generated in situ on the surface of steel after micro-arc oxidation surface treatment. Although it is not as good as valve metals, the strengthening effect is good.

[0067] 3. Simple operation and easy to repeat: By confirming the composition of the electrolyte, the voltage and current changes during the reaction, and the temperature threshold of the electrolyte, the oxidation process can be simply repeated;

[0068] 4. Green and environmentally friendly: The electrolyte used in the experiment is weakly alkaline, which is less harmful to the environment and more environmentally friendly than acidic electrolyte. DETAILED DESCRIPTION

[0069] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the cases implemented are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0070] Example 1

[0071] The spraying method and preparation method of the electrolyte coating on the steel surface of the gun barrel specifically include the following steps:

[0072] Step 1: Pre-treat the substrate: Cut the 32CrNi3MoV steel substrate into 20×20×5mm 3 A small rectangular block is made and a hole with a diameter of 4mm is punched. Then, it is polished with sandpaper ranging from 80# to 1000# until there is no obvious scratch on the surface of the sample. Then, it is polished to remove the residual particles on the surface. Then, it is placed in anhydrous ethanol for ultrasonic cleaning to remove impurities and oil on the surface. Finally, the sample is vacuum dried and waits for use;

[0073] Step 2, preparation of electrolyte: weigh 15 g / L sodium aluminate, 3 g / L sodium dihydrogen phosphate, 3 g / L sodium carbonate, and 3 g / L sodium tetraborate and dissolve them in deionized water, and add 5 mL / L glycerol to the prepared electrolyte. The electrolyte temperature is controlled between room temperature and 40°C.

[0074] Step 3, equipment adjustment: hang the substrate sample in the micro-arc oxidation equipment with a wire, suspend it in the electrolyte, do not touch the bottom, turn on the cooling water circulation and stirring device, the substrate sample is used as the anode, and the inner tank of the micro-arc oxidation machine is used as the cathode to form an electrolytic cell;

[0075] Step 4, electrical parameter setting and monitoring: set the positive voltage to 550V, the negative voltage to -50V, the pulse frequency to 1200Hz, the positive and negative duty cycles to 20%, and the oxidation time to 20min. During the micro-arc oxidation reaction, monitor the voltage, current density, electrolyte temperature and other key parameters in real time to ensure that the micro-arc oxidation reaction proceeds normally;

[0076] Step 5, post-processing and performance testing: After the micro-arc oxidation reaction is completed, the coating sample is taken out, rinsed with water to remove the residual electrolyte on the surface, and then dried and waited for subsequent related performance tests.

[0077] Example 2

[0078] The spraying method and preparation method of the electrolyte coating on the steel surface of the gun barrel specifically include the following steps:

[0079] Step 1: Pre-treat the substrate: Cut the 32CrNi3MoV steel substrate into 20×20×5mm 3 A small rectangular block is made and a hole with a diameter of 4mm is punched. Then, it is polished with sandpaper ranging from 80# to 1000# until there is no obvious scratch on the surface of the sample. Then, it is polished to remove the residual particles on the surface. Then, it is placed in anhydrous ethanol for ultrasonic cleaning to remove impurities and oil on the surface. Finally, the sample is vacuum dried and waits for use;

[0080] Step 2, electrolyte preparation: weigh 15g / L sodium aluminate, 3g / L sodium dihydrogen phosphate, 3g / L sodium carbonate, 3g / L sodium tetraborate and 2g / L α-Al 2 O 3 The nanoparticles were dissolved in deionized water, and 5 mL / L glycerol was added to the prepared electrolyte. The electrolyte temperature was controlled between room temperature and 40 °C.

[0081] Step 3, equipment adjustment: hang the substrate sample in the micro-arc oxidation equipment with a wire, suspend it in the electrolyte, do not touch the bottom, turn on the cooling water circulation and stirring device, the substrate sample is used as the anode, and the inner tank of the micro-arc oxidation machine is used as the cathode to form an electrolytic cell;

[0082] Step 4, electrical parameter setting and monitoring: set the positive voltage to 550V, the negative voltage to -50V, the pulse frequency to 1200Hz, the positive and negative duty cycles to 20%, and the oxidation time to 20min. During the micro-arc oxidation reaction, monitor the voltage, current density, electrolyte temperature and other key parameters in real time to ensure that the micro-arc oxidation reaction proceeds normally;

[0083] Step 5, post-processing and performance testing: After the micro-arc oxidation reaction is completed, the coating sample is taken out, rinsed with water to remove the residual electrolyte on the surface, and then dried and waited for subsequent related performance tests.

[0084] The above-mentioned implementation cases are only preferred cases of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, amendment, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for spraying an electrolyte coating on a steel surface of a gun barrel, characterized in that: The following steps are involved: The pre-treated gun barrel steel is placed in a prepared electrolyte for micro-arc oxidation treatment. A high voltage is applied in the electrolyte to generate a tiny arc discharge, so that the surface of the gun steel is partially melted and rapidly cooled, forming a dense ceramic layer on the surface; Then, the membrane layer is sealed by adding nanoparticles to improve the surface morphology of the membrane layer. During the process, key parameters such as current density, voltage, electrolyte composition and temperature during micro-arc oxidation need to be monitored in real time.

2. The method for spraying electrolyte of steel surface coating based on gun barrel according to claim 1 is characterized in that: Specific operations include: Voltage management and control: Set the voltage before the micro-arc oxidation experiment, and use the power management system to monitor the voltage fluctuations during the reaction in real time. From the beginning of the reaction to the voltage required for the reaction and during the continuous process, if the voltage exceeds the set voltage by ±5%, the power system will adjust the power supply strategy in real time to make the voltage normal, avoid local overheating or uneven oxidation, so as not to affect the molding quality of the film layer; Management and control of current density: The power management system monitors the current density in the reaction process in real time. If the current density exceeds the preset value, the power management system will automatically adjust the current density. If the current is abnormal, the system will automatically cut off the power to protect the machine. Temperature control and adaptation: Place a temperature measurement sensor in the electrolyte to observe the current temperature of the electrolyte in real time; Data recording and analysis: During the oxidation process, various key parameters, including voltage changes, current density, electrolyte temperature, etc., will be recorded for reference in subsequent experiments.

3. A method for preparing an electrolyte for a steel surface coating based on a gun barrel, characterized in that: The micro-arc oxidation electrolyte contains the following electrolyte raw materials: Sodium aluminate (NaAlO2) 15g / L; Sodium dihydrogen phosphate (NaH2PO4) 3g / L; Sodium carbonate (Na2CO3) 3g / L; Sodium tetraborate (Na2B4O7) 3g / L; The rest are deionized water; 5 mL / L of glycerol needs to be additionally added to the electrolyte. Glycerol does not participate in the micro-arc oxidation reaction. Its specific function is to slow down the evaporation effect of the arc generated by the high voltage on the electrolyte.

4. The method for preparing electrolyte for steel surface coating based on gun barrel according to claim 3 is characterized in that: The micro-arc oxidation electrolyte contains the following electrolyte raw materials: Sodium aluminate (NaAlO2) 15g / L; Sodium dihydrogen phosphate (NaH2PO4) 3g / L; Sodium carbonate (Na2CO3) 3g / L; Sodium tetraborate (Na2B4O7) 3g / L; Alumina nanoparticles (α-Al2O3) 3g / L; The rest are deionized water; 5 mL / L of glycerol needs to be added to the electrolyte. Glycerol does not participate in the micro-arc oxidation reaction. Its specific function is to slow down the evaporation of the electrolyte caused by the arc generated by the high voltage. In addition, the particle size of the added α-Al2O3 nanoparticles is 30 nanometers.