CN101838791B - Method for depositing amorphous carbon film by modifying surface of magnesium alloy - Google Patents

Abstract

The invention discloses a method for modifying and depositing an amorphous carbon film on the surface of a magnesium alloy. The method adopts an arc ion plating technology, uses graphite as a cathode target material, and uses arc ion plating on a magnesium alloy at a low temperature to prepare a high hardness and low friction coefficient. , Amorphous carbon film with high bonding strength with substrate, wear resistance and corrosion resistance. The invention has the advantages of simple process, low cost, low deposition temperature and fast deposition speed, and is suitable for large-scale industrial production, and the magnesium alloy modified by depositing amorphous carbon film on the surface can be widely used in the fields of auto parts and aerospace.

Description

A method for modifying the surface of a magnesium alloy to deposit an amorphous carbon film

technical field

The invention belongs to magnesium alloy surface treatment and surface modification technology, in particular to a method for magnesium alloy surface modification and deposition of amorphous carbon film.

Background technique

Magnesium alloys have a series of advantages such as high specific strength and specific stiffness, good toughness, easy forming, vibration resistance, electromagnetic radiation absorption, recyclability and low environmental pollution. As a new generation of green, high-strength and lightweight metal structural materials, it has been widely used in the fields of automobile industry, communication products, aerospace, weapons and equipment. For example, magnesium alloys can be used in various civil and military aircraft engine parts, propellers, gearboxes, bracket structures, and some parts of rockets, missiles, and satellites. These parts are constantly moving, and their actual operating environment is relatively harsh. This puts forward new requirements for the wear resistance and corrosion resistance of magnesium alloys. However, magnesium alloys are soft, have low hardness, poor wear resistance, and are extremely prone to oxidation and corrosion, especially when magnesium alloys are used in aircraft engine parts. These defects greatly limit the practical application of magnesium alloys and the characteristics of parts . Therefore, the surface treatment of magnesium alloys is very important to provide effective protection and improve the surface properties of magnesium alloys. The surface treatment methods for magnesium alloys mainly include anodic oxidation, micro-arc oxidation, laser surface treatment and surface coating. The surface film formed after anodic oxidation is thin and difficult to be used as a wear-resistant layer, and the electrolyte pollutes the environment; A thick oxide film, but loose and porous, the performance of the film layer decreases; laser surface treatment is not conducive to large-scale production due to the limited treatment area, these surface treatment methods have great limitations, and the surface corrosion resistance after treatment And wear resistance are not ideal in actual use. Compared with several other methods, the most effective way to improve the wear resistance and corrosion resistance of the magnesium alloy surface is to prepare a wear-resistant and corrosion-resistant film on the surface, and use the film to form a layer between the magnesium alloy substrate and the external environment. barrier to inhibit corrosion and wear of magnesium alloys.

Amorphous carbon film has good mechanical properties and mechanical properties, such as high hardness, large elastic modulus, low friction coefficient, excellent wear resistance and corrosion resistance, good chemical stability, and is a good surface anti-wear protective film. Amorphous carbon thin film has simple preparation process and good practicability, and has been widely used in the fields of machinery, electronics, optics, thermal, acoustics, medicine and so on.

However, in the prior art, there is no technology of using arc ion plating equipment to modify the surface of magnesium alloy deposited amorphous carbon film.

Contents of the invention

The technical problem to be solved by the invention is to provide a method for modifying and depositing an amorphous carbon film on the surface of a magnesium alloy which is easy to operate.

The technical solution for realizing the purpose of the present invention is: a method for depositing an amorphous carbon film by modifying the surface of a magnesium alloy, using arc ion plating deposition film technology, using graphite as a cathode target, depositing an amorphous carbon film on a magnesium alloy, Specifically include the following steps:

Step 1, carrying out surface pretreatment to the magnesium alloy substrate;

Step 2, fixing the magnesium alloy substrate on the substrate holder in the vacuum chamber of the arc ion plating equipment, and evacuating the vacuum chamber of the arc ion plating equipment;

Step 3, passing argon gas into the vacuum chamber, then igniting the arc, applying a high bias voltage on the magnesium alloy substrate to bombard and clean the surface of the magnesium alloy;

Step 4, feed the deposition gas into the vacuum chamber, adjust the deposition atmosphere, reduce the bias voltage of the magnesium alloy substrate, adjust the temperature of the magnesium alloy substrate, control the arc current and arc voltage of the graphite arc source, and deposit amorphous on the surface of the magnesium alloy carbon film;

Step 5. After the deposition is completed, turn off the arc power supply and bias voltage, and turn off the gas. After the workpiece is cooled to room temperature in the vacuum chamber, open the vacuum chamber to take out the sample.

Compared with the prior art, the present invention has significant advantages: 1) The amorphous carbon film is deposited on the magnesium alloy substrate by using the arc ion plating thin film technology, and the film and the magnesium alloy have high bonding strength, a thickness exceeding 1 μm, high hardness and low friction. The coefficient is small, wear-resistant and corrosion-resistant; 2) the present invention can realize the low-temperature deposition of the amorphous carbon film on the surface of the magnesium alloy, and the deposited film is uniform and compact; 3) the present invention deposits the amorphous carbon film on the magnesium alloy surface The ionization rate is high, the deposition speed is fast, and the film growth speed is fast; 4) The process and equipment of the present invention are simple and easy to implement, adopt low voltage operation, safe operation, use graphite targets, and have low cost, and are suitable for large-scale industrial production; 5) The present invention deposits the amorphous carbon film on the magnesium alloy, and the magnesium alloy after surface modification can be widely used in the fields of auto parts and aerospace.

Detailed ways

Arc ion plating equipment is a common equipment for depositing amorphous carbon films. A method for depositing amorphous carbon films on the surface of magnesium alloys according to the present invention adopts arc ion plating technology and uses graphite as the cathode target. Depositing an amorphous carbon film on it, specifically comprising the following steps:

Step 1. Perform surface pretreatment on the magnesium alloy substrate; specifically: sandpaper, polish, degrease, and decontaminate the magnesium alloy substrate, and then put it in acetone or alcohol and use an ultrasonic cleaning machine for ultrasonic cleaning. blow dry.

Step 2, fixing the magnesium alloy substrate on the substrate holder in the vacuum chamber of the arc ion plating equipment, and vacuumizing the vacuum chamber of the arc ion plating equipment; the vacuum degree of the arc ion plating equipment after vacuuming is less than or equal to 3×10 ^{− 3Pa} .

Step 3. Pass argon gas into the vacuum chamber, then ignite the arc, and apply a high bias voltage on the magnesium alloy substrate to bombard and clean the surface of the magnesium alloy; the distance between the graphite target and the magnesium alloy substrate is 100-400mm; The vacuum degree of the vacuum chamber after argon is 0.1-1Pa; the arc current of the arc is 20-50A, and the arc voltage is 20V-30V; the high bias voltage applied on the magnesium alloy substrate is a pulse bias voltage, and the high bias voltage is - 600V～-1000V, the duty ratio is 10%-40%; the bombardment cleaning time is 1-5 minutes.

Step 4, feed the deposition gas into the vacuum chamber, adjust the deposition atmosphere, reduce the bias voltage of the magnesium alloy substrate, adjust the temperature of the magnesium alloy substrate, control the arc current and arc voltage of the graphite arc source, and deposit amorphous on the surface of the magnesium alloy Carbon thin film; the deposition gas introduced into the above-mentioned vacuum chamber is a mixture of one or two or more of argon, hydrogen, nitrogen, and hydrocarbon gases, and the pressure after the gas is introduced is 0.05-5Pa; the magnesium alloy substrate The bias voltage is 0-400V, the duty cycle is 10%-40%, the temperature of the magnesium alloy substrate is 25-200°C, the arc current of the graphite arc source is 20-50A, and the arc voltage is 20-30V.

Step 5. After the deposition is completed, turn off the arc power supply and bias voltage, and turn off the gas. After the workpiece is cooled to room temperature in the vacuum chamber, open the vacuum chamber to take out the sample.

Below in conjunction with embodiment the present invention is described in further detail:

Example 1:

AZ91 magnesium alloy is selected and processed into a square with a side length of 10mm and a thickness of 3mm.

The specific operation steps are:

(1) Magnesium alloy pretreatment: use ordinary detergent to degrease and decontaminate the processed magnesium alloy substrate, then polish the sample with 400-1200 ^# sandpaper in sequence, and finally polish the surface. Put the polished magnesium alloy into acetone or alcohol for ultrasonic cleaning for 10 minutes with an ultrasonic cleaning machine, and dry it with cold air before use.

(2) Take the cleaned and polished magnesium alloy as the substrate substrate, place it in the vacuum chamber of the arc ion plating equipment, and fix it on the substrate holder in the vacuum chamber. The fixed position of the magnesium alloy substrate is facing the graphite target. And the distance from the target is 100mm. Then close the vacuum chamber, and evacuate to a background vacuum equal to 3×10 ^-3 Pa by means of a mechanical pump and a diffusion pump. When the background vacuum is reached, open the gas valve to feed high-purity argon gas; when the vacuum degree is stable at 0.2Pa, turn on the graphite arc source, the arc current is 20A, the arc voltage is 20V; the pulse bias is adjusted to -600V, The empty ratio is 40%, and the magnesium alloy substrate is bombarded and cleaned for 5 minutes to remove residual oxides and residual impurities on the substrate surface.

(3) After the bombardment cleaning of the magnesium alloy substrate is completed, the argon gas is continuously introduced to deposit an amorphous carbon film on the surface of the magnesium alloy. The pulse bias voltage applied to the magnesium alloy substrate was adjusted to -50V, the duty cycle was 20%; the working pressure was 0.08Pa; the deposition temperature was 150°C; the arc current was 20A, the arc voltage was 20V; the deposition time was 12min.

(4) After the deposition of the amorphous carbon film is completed, the arc power supply and pulse bias voltage are turned off, and the gas is turned off. After the workpiece is cooled to room temperature in the vacuum chamber, the vacuum chamber is opened to take out the sample.

The performance test of the amorphous carbon film deposited on the magnesium alloy is as follows:

Friction coefficient of amorphous carbon film: 0.15; friction and wear test conditions are: load 2N, sliding speed 10cm/s, friction pair is 100Cr6 steel, humidity 40%, temperature 20-25°C, friction distance 125m.

The wear scar Raman spectrum of the amorphous carbon film after rubbing shows that the structure of the amorphous carbon film is stable and does not change during the rubbing process.

Example 2:

AZ91 magnesium alloy is selected and processed into a square with a side length of 10mm and a thickness of 3mm.

The specific operation steps are:

(1) Magnesium alloy pretreatment: use ordinary detergent to degrease and decontaminate the processed magnesium alloy substrate, then polish the sample with 400-1200 ^# sandpaper in sequence, and finally polish the surface. Put the polished magnesium alloy into acetone or alcohol for ultrasonic cleaning with an ultrasonic cleaning machine for 15 minutes, and dry it with cold air before use.

(2) Take the cleaned and polished magnesium alloy as the substrate substrate, place it in the vacuum chamber of the arc ion plating equipment, and fix it on the substrate holder in the vacuum chamber. The fixed position of the magnesium alloy substrate is facing the graphite target. And the distance from the target is 400mm. Then close the vacuum chamber, and evacuate to a background vacuum equal to 3×10 ^-3 Pa by means of a mechanical pump and a diffusion pump. When the background vacuum is reached, open the gas valve to feed high-purity argon gas; when the vacuum degree is stable at 1Pa, turn on the graphite arc source, the arc current is 50A, the arc voltage is 30V; the pulse bias is adjusted to -1000V, and the duty cycle The ratio is 30%, and the magnesium alloy substrate is bombarded and cleaned for 1.5 minutes to remove residual oxides and residual impurities on the surface of the substrate.

(3) After the bombardment cleaning of the magnesium alloy substrate is completed, the argon gas is continuously introduced to deposit an amorphous carbon film on the surface of the magnesium alloy. The pulse bias voltage applied to the magnesium alloy substrate was adjusted to -400V, the duty cycle was 30%; the working pressure was 0.5Pa; the deposition temperature was 200°C; the arc current was 50A, the arc voltage was 30V; the deposition time was 15min.

(4) After the deposition of the amorphous carbon film is completed, the arc power supply and pulse bias voltage are turned off, and the gas is turned off. After the workpiece is cooled to room temperature in the vacuum chamber, the vacuum chamber is opened to take out the sample.

The performance test of the amorphous carbon film deposited on the magnesium alloy is as follows:

Friction coefficient of hydrogen-containing amorphous carbon film: 0.12; friction and wear test conditions are: load 2N, sliding speed 10cm/s, friction pair is 100Cr6 steel, humidity 40%, temperature 20-25°C, friction distance 125m.

The wear scar Raman spectrum of the amorphous carbon film after rubbing shows that the structure of the amorphous carbon film is stable and does not change during the rubbing process.

Example 3:

AZ91 magnesium alloy is selected and processed into a square with a side length of 15 mm and a thickness of 3 mm.

The specific operation steps are:

(1) Magnesium alloy pretreatment: use ordinary detergent to degrease and decontaminate the processed magnesium alloy substrate, then polish the sample with 400-1200 ^# sandpaper in sequence, and finally polish the surface. Put the polished magnesium alloy into acetone or alcohol for ultrasonic cleaning with an ultrasonic cleaning machine for 20 minutes, and dry it with cold air before use.

(2) Take the cleaned and polished magnesium alloy as the substrate substrate, place it in the vacuum chamber of the arc ion plating equipment, and fix it on the substrate holder in the vacuum chamber. The fixed position of the magnesium alloy substrate is facing the graphite target. And the distance from the target is 250mm. Then close the vacuum chamber, and evacuate to a background vacuum equal to 3×10 ^-3 Pa by means of a mechanical pump and a diffusion pump. When the background vacuum is reached, open the gas valve to feed high-purity argon gas; when the vacuum degree is stable at 0.5Pa, turn on the graphite arc source, the arc current is 35A, the arc voltage is 25V; the pulse bias is adjusted to -800V, The empty ratio is 20%, and the magnesium alloy substrate is bombarded and cleaned for 3 minutes, so as to remove residual oxides and residual impurities on the surface of the substrate.

(3) After the magnesium alloy substrate is bombarded and cleaned, the argon gas is turned off, and high-purity hydrogen gas is introduced to deposit an amorphous carbon film on the surface of the magnesium alloy. The pulse bias applied to the magnesium alloy substrate was adjusted to -200V, the duty cycle was 40%; the working pressure was 3Pa; the deposition temperature was 100°C; the arc current was 35A, the arc voltage was 25V; the deposition time was 10min.

(4) After the deposition of the amorphous carbon film is completed, the arc power supply and pulse bias voltage are turned off, and the gas is turned off. After the workpiece is cooled to room temperature in the vacuum chamber, the vacuum chamber is opened to take out the sample.

The performance test of the amorphous carbon film deposited on the magnesium alloy is as follows:

Friction coefficient of amorphous carbon film: 0.11; friction and wear test conditions are: load 2N, sliding speed 10cm/s, friction pair is 100Cr6 steel, humidity 40%, temperature 20-25°C, friction distance 125m.

The wear scar Raman spectrum of the amorphous carbon film after rubbing shows that the structure of the amorphous carbon film is stable and does not change during the rubbing process.

Example 4:

AZ91 magnesium alloy is selected and processed into a square with a side length of 15 mm and a thickness of 3 mm.

The specific operation steps are:

(1) Magnesium alloy pretreatment: use ordinary detergent to degrease and decontaminate the processed magnesium alloy substrate, then polish the sample with 400-1200 ^# sandpaper in sequence, and finally polish the surface. Put the polished magnesium alloy into acetone or alcohol for ultrasonic cleaning with an ultrasonic cleaner for 25 minutes, and dry it with cold air before use.

(2) Take the cleaned and polished magnesium alloy as the substrate substrate, place it in the vacuum chamber of the arc ion plating equipment, and fix it on the substrate holder in the vacuum chamber. The fixed position of the magnesium alloy substrate is facing the graphite target. And the distance from the target is 200mm. Afterwards, the vacuum chamber was closed, and the mechanical pump and the diffusion pump were used to evacuate until the background vacuum degree was equal to 3×10 ^-3 Pa. When the background vacuum is reached, open the gas valve to feed high-purity argon gas; when the vacuum degree is stable at 0.8Pa, turn on the graphite arc source, the arc current is 30A, the arc voltage is 20V; the pulse bias is adjusted to -900V, The empty ratio is 15%, and the magnesium alloy substrate is bombarded and cleaned for 4 minutes to remove residual oxides and residual impurities on the surface of the substrate.

(3) After the magnesium alloy substrate is bombarded and cleaned, the argon gas is turned off, high-purity acetylene is introduced, and an amorphous carbon film is deposited on the surface of the magnesium alloy. The pulse bias applied to the magnesium alloy substrate was adjusted to -100V, the duty ratio was 15%; the working pressure was 1Pa; the deposition temperature was 100°C; the arc current was 25A, the arc voltage was 25V; the deposition time was 8min.

(4) After the deposition of the amorphous carbon film is completed, the arc power supply and pulse bias voltage are turned off, and the gas is turned off. After the workpiece is cooled to room temperature in the vacuum chamber, the vacuum chamber is opened to take out the sample.

The performance test of the amorphous carbon film deposited on the magnesium alloy is as follows:

Friction coefficient of amorphous carbon film: 0.13; friction and wear test conditions are: load 2N, sliding speed 10cm/s, friction pair is 100Cr6 steel, humidity 40%, temperature 20-25°C, friction distance 125m.

The wear scar Raman spectrum of the amorphous carbon film after rubbing shows that the structure of the amorphous carbon film is stable and does not change during the rubbing process.

Claims (1)

1. the method for a depositing amorphous carbon film by modifying surface of magnesium alloy is characterized in that, adopts arc ion plating (aip), is cathode targets with graphite, and depositing amorphous carbon film on magnesium alloy specifically may further comprise the steps:

Step 1, the magnesium alloy substrate is carried out surface preparation, be specially: the magnesium alloy substrate is carried out sand papering, polishing, oil removing, decontamination handle, put into acetone or alcohol afterwards and utilize the ultrasonic cleaning machine to carry out ultrasonic cleaning, cold wind dries up;

Step 2, the magnesium alloy substrate is fixed on the substrate support in the arc ion plating apparatus vacuum chamber, and the arc ion plating apparatus vacuum chamber is vacuumized, the vacuum tightness after vacuumizing is less than or equal to 3 * 10 ^-3Pa;

Step 3, argon gas is fed vacuum chamber, the electric arc that ignites afterwards applies high bias voltage Mg alloy surface is bombarded cleaning on the magnesium alloy substrate; The distance of graphite target and magnesium alloy substrate is 100-400mm; The vacuum tightness that feeds argon gas final vacuum chamber is 0.1-1Pa; The arc current of electric arc is that 20-50A, arc voltage are 20-30V; The high bias voltage that applies on the magnesium alloy substrate is a pulsed bias, this high bias voltage is-600～-1000V, dutycycle is 10%-40%; The bombardment scavenging period is 1-5 minute;

Step 4, feed deposition gases in vacuum chamber, adjust deposition atmosphere, reduce the bias voltage of magnesium alloy substrate, adjust the temperature of magnesium alloy substrate, the arc current and the arc voltage in control graphite arc source are at the Mg alloy surface depositing amorphous carbon film; The deposition gases that feeds in the vacuum chamber is one or more the mixing in argon gas, hydrogen, nitrogen, the hydrocarbon gas, and the pressure that feeds behind the gas is 0.05-5Pa; The bias voltage of magnesium alloy substrate is 0--400V, dutycycle 10%-40%; The temperature of magnesium alloy substrate is 25-200 ℃; The arc current in graphite arc source is that 20-50A, arc voltage are 20-30V;

After step 5, deposition finish, close arc power and bias voltage, close gas, treat magnesium alloy substrate cool to room temperature in vacuum chamber of depositing amorphous carbon film, open vacuum chamber and taking-up.