CN108546949A - Preparation method of titanium alloy body coating based on electric spark deposition - Google Patents

Abstract

The invention discloses a preparation method of a titanium alloy body coating based on electric spark deposition, which comprises the following steps: the titanium alloy material is used as a matrix, the titanium alloy with the same type as the matrix material is used as an electrode, and the electric spark deposition mode is adopted to deposit and form a titanium alloy body coating on the surface of the titanium alloy matrix. The deposition process has excellent performance, the prepared coating is metallurgically bonded with the base material, the interface bonding is good, the coating structure is compact, the diversity of titanium alloy processing technology is increased, the production efficiency is improved, and the method has strong practical value.

Description

A preparation method of titanium alloy body coating based on electric discharge deposition

technical field

The invention relates to the field of preparation of metal coatings, in particular to an electric spark deposition method for manufacturing titanium alloy coatings.

Background technique

Titanium has the advantages of high specific strength, excellent corrosion resistance, and good biocompatibility, and is widely used in aerospace, weaponry, and civil industries. In particular, it is an ideal manufacturing material for aircraft and engines. For example, the amount of titanium alloy used in F-15 fighter jets accounts for about 26.5% of the weight of the entire aircraft structure, and the amount of titanium alloy used in Boeing 747 large passenger aircraft reaches 5.5%.

However, due to the poor machinability of titanium alloys, its application has been largely restricted for a long time. The main reasons for poor machinability are: ① Poor thermal conductivity, resulting in high cutting temperature and reducing tool durability. ②When the temperature is above 600°C, the surface of titanium alloy is easy to form an oxidized hard layer, which has a strong abrasive effect on the knife. ③Low plasticity and high hardness increase the shear angle, the contact length between the chip and the rake face is small, the stress on the rake face is large, and the blade is prone to damage. ④ The elastic modulus is low, the elastic deformation is large, and the surface rebound of the workpiece near the flank is large, so the contact area between the machined surface and the flank is large and the wear is serious. These characteristics in the cutting process of titanium alloy make it very difficult to process, resulting in low processing efficiency and high tool consumption. In addition to the poor cutting performance of titanium alloys, the drilling of titanium alloys is also difficult, and burning and broken drills often occur during processing.

In view of the above reasons, the present invention adopts electric spark deposition technology to process titanium alloy, and electric spark deposition (ESD) is a simple and cost-effective technology. It uses capacitors to store high-energy electric energy, and then releases high-energy electric energy at high frequency between the metal electrode (anode) and the metal substrate (cathode), causing the ionization of the air or working medium and forming a discharge channel between the electrode material and the workpiece. This electrical discharge creates a tiny, high-temperature, high-pressure area on the surface of the workpiece. High temperature and high pressure can melt the electrode material and penetrate into the surface of the workpiece to form a metallurgical coating with high hardness and high wear resistance. The process has many advantages such as small heat input, simple equipment, high bonding strength of the deposited layer, and local strengthening of the surface of the part.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a body coating on a titanium alloy substrate by using an electric spark deposition technique, so as to increase the diversity of titanium alloy processing techniques.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a titanium alloy body coating based on electric spark deposition, characterized in that: a titanium alloy material is used as a substrate, a titanium alloy of the same type as the substrate material is used as an electrode, and an electric spark deposition method is used to deposit on the surface of the titanium alloy substrate A titanium alloy body coating is formed.

Further, the method is specifically prepared according to the following steps:

(1) use titanium alloy as substrate and electrode respectively, polish substrate and electrode surface with sandpaper, remove surface oxide film, then remove surface stain to obtain pretreated substrate and pretreated electrode; the material titanium alloy of described substrate, electrode The model remains the same;

(2) With an electric spark deposition device, the pre-treated substrate obtained in step (1) is fixed on the workbench, and the pre-treated substrate is connected to the positive pole of the electric spark deposition device pulse power supply, and the pre-treated electrode is fixed on the working gun, and the working gun is connected with the negative electrode of the pulse power supply of the electric spark deposition device; The processed electrode moves back and forth regularly on the surface of the pre-treated substrate, and finally forms a titanium alloy body coating on the pre-treated substrate; the pre-treated electrode matches the working gun.

Further, in step (1), the method for removing surface stains is to use absolute ethanol or acetone to ultrasonically clean the substrate and electrodes.

Further, in step (1), the electrode is in the shape of a round rod, and the discharge area of the electrode head is in the shape of a cone;

Still further, the cone angle of the discharge region of the electrode head is 10-170°.

Further, in step (1), the titanium alloy is preferably TC4, TC6, TB5, TA15 or TA2.

Further, in step (2), the protective gas is a mixture of one or more of argon, helium, carbon dioxide gas, hydrogen or nitrogen, preferably argon or nitrogen.

Further, in step (2), the protection method of the protective gas is that the deposition test is carried out in a sealed system, and the protective gas is filled into the sealed system before the test, and at the same time, the oxygen concentration in the device is monitored in real time by an oxygen meter. When the oxygen concentration in the device drops below 0.5%, start the spark deposition test, and keep the oxygen concentration in the device below 0.5% during the test.

Further, in step (2), the deposition parameters of the electric spark deposition device are: output power 100-5000W, discharge voltage 24-100V, discharge pulse width 10-1000μs.

Further, in step (2), there is a gap between the pre-treated electrode and the pre-treated substrate, which can cause the medium (such as protective gas) between the electrode and the substrate to be ionized and broken down, and then in the pre-treated The distance at which spark discharge occurs between the electrode and the pretreated substrate is preferably 0.1-60 μm.

Further, in step (2), the pre-treatment electrodes are kept moving at a constant speed as far as possible to ensure the quality of the deposited layer, preferably the moving speed is 10-600 mm/min.

More specifically, the whole set of experimental equipment for the method of preparing titanium alloy body coating based on EDM technology described in the present invention includes: protective gas cylinder, working gun, EDM device, sealing device, vise and oxygen meter The vise is used to clamp the substrate, and the sealing device is used to surround the vise after the substrate is clamped so that the vise is in an airtight seal, and the vent port of the protective gas tank is connected to the sealing device , the oxygen measuring probe of the vise oxygen measuring instrument extends into the sealing device, the cathode of the electric spark deposition device can be electrically connected with the substrate, and the anode of the electric spark deposition device is connected to the The working gun is electrically connected; the sealing device is provided with a working gun interface closely matched with the working gun; when the electric spark deposition device is working, the substrate is connected to the positive interface of the electric spark deposition device and passed through The vise knob is fixed on the vise, and the vise is airtightly placed in the sealing device; the end of the working gun is provided with a working gun chuck, and the electrode is fixed on the working gun chuck , the working gun is connected to the anode interface of the electric spark deposition device; the shielding gas tank is connected to the sealing device, and the oxygen measuring probe of the oxygen meter monitors the oxygen content in the sealing device in real time The working gun is airtightly connected with the sealing device through the working gun interface. When the experiment starts, open the gas valve of the protective gas tank, and feed the protective gas into the sealing device until the concentration of oxygen is reduced to 0.5%. , turn on and adjust the electric spark deposition device and adjust the power adjustment knob and the mode adjustment knob, turn on the working gun switch and close the end of the working gun with the electrode fixed to the substrate for the electric spark deposition test.

Compared with prior art, the beneficial effect of the present invention is:

The invention forms a metallurgically bonded body coating on the surface of the titanium alloy that will not fall off, and opens up a new approach for processing the titanium alloy. The invention can obtain body coatings with different performance requirements by adjusting parameters such as electrical parameters and deposition time, and has high practical value for improving the manufacturing technology of titanium alloy parts. The deposition process of the present invention has excellent performance, the prepared coating is metallurgically bonded to the base material, the interface is well bonded, and the coating structure is compact, which can perfectly repair the damaged part of the test piece, prolong the service life of the test piece, and has strong practical value .

Description of drawings

Fig. 1 is the typical microstructure figure of the embodiment of the present invention 1;

Fig. 2 is a typical microstructure diagram of Example 3 of the present invention;

Fig. 3 is a typical microstructure diagram of Example 5 of the present invention;

Figure 4 is the diagram of the EDM test device; 1 is the micro-arc spark deposition device, 2 is the anode interface, 3 is the working gun, 4 is the substrate, 5 is the vise knob, 6 is the atmosphere protection glove bag, and 7 is the oxygen measuring probe , 8 is the vise, 9 is the electrode, 10 is the chuck of the working gun, 11 is the cathode interface, 12 is the power adjustment knob, 13 is the mode adjustment knob, 14 is the gas valve, 15 is the protective gas tank, 16 is the oxygen meter .

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments, which do not limit the scope of the present invention. Fig. 1 is a typical microstructure diagram of the TC4 body coating of the present invention; Fig. 2 is a typical microstructure diagram of the TA2 body coating of the present invention. In the figure: 1—coating, 2—substrate.

The whole set of experimental equipment for the method of preparing columnar array surface based on EDM technology in the present invention includes: shielding gas tank 15, working gun 3, EDM device 1, atmosphere protection glove bag 6, vise 8 and oxygen meter 16. The vise 8 is used to clamp the substrate, and the atmosphere protection glove bag is used to wrap the vise after the substrate is clamped so that the vise is airtight, and the vent port of the protective gas tank 15 is in contact with the The atmosphere protection glove bag 6 is connected, the oxygen measuring probe of the vise oxygen meter 16 extends into the atmosphere protection glove bag, and the cathode of the electric spark deposition device 1 can be electrically connected with the substrate , the anode of the electric spark deposition device is electrically connected to the working gun 3; the atmosphere protection glove bag is provided with a working gun interface closely matched with the working gun; when the electric spark deposition device is working, the The substrate 4 is connected to the cathode interface 11 of the electric spark deposition device 1 and fixed on the vise 8 through the vise knob 5, and the vise 8 is airtightly placed in the atmosphere protection glove bag 6; The end of the working gun 3 is provided with a working gun chuck 10, and the electrode 9 is fixed on the described working gun chuck 10, and the described working gun 3 is connected with the anode interface 2 of the described electric spark deposition device 1; The protective gas tank 15 is connected with the atmosphere protection glove bag 6, and the oxygen measuring probe 7 of the oxygen meter 16 monitors the oxygen content in the atmosphere protection glove bag in real time; the working gun passes through the The working gun interface is airtightly connected with the atmosphere protection glove bag 6. When the experiment starts, open the gas valve 14 of the shielding gas tank, and feed the shielding gas into the atmosphere protection glove bag 6 until the oxygen concentration is reduced to 0.05% to 0.5%. , turn on and adjust the EDM device 1 and adjust the power adjustment knob 12 and the mode adjustment knob 13, and place the end of the working gun 3 fixed with the electrode 9 close to the substrate 4 to conduct the EDM test.

Example 1:

The base material is TC4, and the electrode material is TC4. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 15°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 500W, discharge voltage 30V, discharge pulse width 20μs, deposition test is carried out in the atmosphere protection glove bag, before the test, go to the atmosphere protection glove bag to fill the protection gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.04%-0.08%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 5min. Finally, a titanium alloy bulk coating is formed on the substrate as shown in Figure 1. The coating structure is uniform and compact, with a thickness of about 480 μm and no obvious defects. An irregular fusion line is formed between the coating and the substrate. The coating is uniform and without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Example 2:

The base material is TC4, and the electrode material is TC4. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 30°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 1000W, discharge voltage 45V, discharge pulse width 60μs, deposition test is carried out in the atmosphere protection glove bag, before the test go to the atmosphere protection glove bag to fill the protection gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.04%-0.08%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 5min. Finally, a titanium alloy body coating is formed on the substrate. The coating structure is uniform and dense, and the appearance is basically the same as that of Example 1, but the thickness is different, and the thickness is about 400 μm. There are no obvious defects. An irregular fusion line, the joint is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Example 3:

The base material is TC4, and the electrode material is TC4. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 50°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 2200W, discharge voltage 60V, discharge pulse width 220μs, deposition test is carried out in the atmosphere protection glove bag, before the test, go to the atmosphere protection glove bag to fill the protection gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.1% and 0.15%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 5min. Finally, a titanium alloy body coating is formed on the substrate as shown in Figure 3. The coating structure is uniform and dense, with a thickness of about 340 μm. There are a few cracks and pores in the coating, and an irregular line is formed between the coating and the substrate. The fusion line, the joint is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Example 4:

The base material is TC4, and the electrode material is TC4. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 70°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 3000W, discharge voltage 60V, discharge pulse width 480μs, deposition test is carried out in the atmosphere protection glove bag, before the test, go to the atmosphere protection glove bag to fill the protection Gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.3%, and the test is started, the electrode is close to the surface of the substrate, and the electrode is on the surface of the substrate Continuously move regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 5min. Finally, a titanium alloy body coating is formed on the substrate, the appearance is basically the same as in Example 3, but the thickness is different, the coating structure is uniform and dense, and the thickness is about 350 μm. There are a few cracks and pores in the coating. The coating and the substrate An irregular fusion line is formed between them, the junction is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Example 5:

The base material is TA2, and the electrode material is TA2. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 45°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply. The specific process parameters for deposition are: output power 3800W, discharge voltage 55V, discharge pulse width 360μs. The deposition test is carried out in the atmosphere protection glove bag. gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.1% and 0.15%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 3min. Finally, a titanium alloy body coating is formed on the substrate as shown in Figure 3. The coating structure is uniform and dense, with a thickness of about 100 μm. There are a few cracks and pores in the coating, and an irregular line is formed between the coating and the substrate. The fusion line, the joint is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Embodiment 6:

The base material is TA2, and the electrode material is TA2. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 60°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 4600W, discharge voltage 80V, discharge pulse width 640μs, deposition test is carried out in the atmosphere protection glove bag, before the test, go to the atmosphere protection glove bag to fill the protection gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.05% and 0.1%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 3min. Finally, a titanium alloy body coating is formed on the substrate. The coating structure is uniform and compact, and the appearance is basically the same as that of Example 5. The thickness is about 120 μm. There are a few cracks and pores in the coating, and a gap is formed between the coating and the substrate. An irregular fusion line, the joint is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Embodiment 7:

The base material is TA2, and the electrode material is TA2. Concrete preparation steps are as follows:

(1) Grind the substrate and electrode to be used for EDM deposition step by step with 400#, 800#, 1200# sandpaper to remove the oxide film on the surface of the material, and then ultrasonically clean it with absolute ethanol for 6 minutes to remove surface stains;

(2) Process one end of the electrode material into a conical shape with a cone angle of 60°;

(3) The substrate is connected to the positive pole of the pulse power supply of the 3H-ES-6 type electric spark deposition device, and the bottom end of the electrode cone is fixed on the working gun, and the described working gun is pulsed with the described electric spark deposition device connected to the negative pole of the power supply;

(4) Turn on the pulse power supply, the specific process parameters of deposition are: output power 2800W, discharge voltage 60V, discharge pulse width 180μs, the deposition test is carried out in the atmosphere protection glove bag, before the test, go to the atmosphere protection glove bag to fill the protection gas argon, and at the same time use an oxygen meter to monitor the oxygen concentration in the device in real time, so that the oxygen concentration in the airtight device is controlled between 0.15% and 0.2%. The surface of the substrate moves regularly, the electrode moves at a constant speed of 100mm/min, and the deposition time is 3min. Finally, a titanium alloy body coating is formed on the substrate. The coating structure is uniform and dense, and the appearance is basically the same as that of Example 5. The thickness is about 90 μm. There are a few cracks and pores in the coating, and a gap between the coating and the substrate is formed. An irregular fusion line, the joint is uniform without gaps, and the coating and the substrate have achieved good metallurgical bonding.

Claims (10)

1. A method for preparing a titanium alloy body coating based on spark deposition, characterized in that: the method is prepared according to the following steps: (1) use titanium alloy as substrate and electrode respectively, polish substrate and electrode surface with sandpaper, remove surface scale, then remove surface stain to obtain pretreated substrate and pretreated electrode; the material titanium alloy of described substrate, electrode The model remains the same; (2) With an electric spark deposition device, the pre-treated substrate obtained in step (1) is fixed on the workbench, and the pre-treated substrate is connected to the negative electrode of the electric spark deposition device pulse power supply, and the pre-treated electrode is fixed on the working gun, the working gun is connected to the positive pole of the pulse power supply of the electric spark deposition device, under the protective gas atmosphere, the pre-treated electrode is brought close to the surface of the pre-treated substrate The processed electrode moves back and forth continuously on the surface of the pre-treated substrate, and finally forms a titanium alloy body coating on the pre-treated substrate; the pre-treated electrode matches the working gun. 2. The method according to claim 1, characterized in that: in step (1), the method for removing surface stains is to use absolute ethanol or acetone to ultrasonically clean the substrate and electrodes. 3. The method according to claim 1, characterized in that: in step (1), the electrode is in the shape of a round rod, and the discharge area at the head of the electrode is in the shape of a cone. 4. The method according to claim 3, characterized in that: in step (1), the cone angle of the discharge region of the electrode head is 10-170°. 5. The method according to claim 1, characterized in that: in step (1), the titanium alloy is an α-titanium alloy, a near-α-titanium alloy, a β-titanium alloy or a duplex titanium alloy. 6. The method according to claim 1, characterized in that in step (2), the protective gas is a mixture of one or more of argon, helium, carbon dioxide gas, hydrogen or nitrogen. 7. The method according to claim 1 or 6, characterized in that: in the step (2), the protection mode of the protective gas is that the deposition test is carried out in a sealed system, and the protective gas is charged in the sealed system before the test, At the same time, an oxygen meter is used to monitor the oxygen concentration in the device in real time. When the oxygen concentration in the device drops below 0.5%, the spark deposition test is started, and the oxygen concentration in the device is always kept below 0.5% during the test. 8. The method according to claim 1, characterized in that: in step (2), the deposition parameters of the EDM device are: output power 100-5000W, discharge voltage 24-100V, discharge pulse width 10-1000μs. 9. The method according to claim 1, characterized in that in step (2), the distance between the pre-treated electrode and the pre-treated substrate is 0.1-60 μm. 10. The method according to claim 1, characterized in that in step (2), the pre-treated electrode moves at a constant speed, and the moving speed is 10-600 mm/min.