CN113564549A

CN113564549A - Method for depositing DLC (diamond-like carbon) thick film by high-density plasma composite carbon source

Info

Publication number: CN113564549A
Application number: CN202110757165.3A
Authority: CN
Inventors: 李海涛; 程东海; 张体明; 戎易; 李文杰; 刘钊泽
Original assignee: Nanchang Hangkong University
Current assignee: Nanchang Hangkong University
Priority date: 2021-07-05
Filing date: 2021-07-05
Publication date: 2021-10-29
Anticipated expiration: 2041-07-05
Also published as: CN113564549B

Abstract

The invention discloses a method for depositing DLC thick film by high-density plasma composite carbon source, which comprises five steps of pretreatment of a substrate, preparation before coating, preparation of Ti-Si transition buffer layer, DLC thick film preparation, aging and liquid nitrogen cooling, wherein the method applies pulse and bias power supply to magnetron sputtering technology, the method is simple, the deposition efficiency of the thick film is high, the performance of the thick film is excellent, the method is suitable for protecting various metal matrixes, the method is an advanced method for preparing the thick film, a high-density mixed gas carbon source is adopted in the magnetron sputtering process, the plasma density is high, the glow is continuous and stable, the prepared thick film is compact and uniform, the hardness is improved, and the corrosion resistance is improved, so that the method has important significance and prospect for improving the surface performance of some metal matrixes, expanding the application of some metal matrixes, reducing abrasion, oxidation and corrosion and saving resources. The method is used for preparing the high-hardness corrosion-resistant DLC thick film.

Description

Method for depositing DLC (diamond-like carbon) thick film by high-density plasma composite carbon source

Technical Field

The invention relates to the technical field of surface coatings and materials, in particular to a method for depositing a DLC thick film by using a high-density plasma composite carbon source.

Background

Resource consumption is an important problem facing human sustainable development at present. The metal material has wide application in various fields such as military chemical industry, aerospace, transportation, production and construction, machining, electronic industry and the like, and can be said to cover all the fields. However, for some metal materials, a large amount of metal materials are often consumed due to factors such as abrasion, corrosion and high-temperature oxidation, so that not only are resources wasted and the cost increased, but also significant potential safety hazards exist. For example, the magnesium alloy member is severely worn and corroded, and a steel material is corroded and oxidized. The development of the surface coating technology brings good news for solving the problems, the performance of the matrix can be obviously improved on the premise of ensuring the performance of the matrix, and the wear rate and corrosion rate of the matrix material are greatly reduced. However, the thickness of the traditional film is limited, generally less than 10 μm, so that the improvement of the wear resistance and corrosion resistance of the matrix material is very limited. DLC thick film is a better amorphous carbon material, the lubrication and thickness guarantee of carbon element, stable structure and inertia of the DLC thick film, excellent heat conduction and heat dissipation capacity and the like of the DLC thick film, and can solve the consumption loss of abrasion, corrosion, oxidation and the like in most application occasions. Moreover, the DLC amorphous structure eliminates columnar crystals and reduces the passage of corrosive ions into the matrix through grain boundaries, which is also a great benefit for the improvement of corrosion resistance. Therefore, the invention has very important significance.

Disclosure of Invention

The invention aims to solve the problems that: the method for depositing the DLC thick film by the high-density plasma composite carbon source can solve the problems of low hardness of the metal surface, no wear resistance, easy oxidation and easy corrosion.

The technical scheme provided by the invention for solving the problems is as follows: a method of high density plasma composite carbon source deposition of a DLC thick film, the method comprising the steps of:

firstly, pretreatment of a substrate: cutting and sampling a substrate, grinding the substrate by metallographic abrasive paper with different meshes, cleaning the substrate in an aqueous solution of oxalic acid, citric acid and sodium benzenesulfonate, and then cleaning the substrate in NaHCO₃Soaking the neutralized residual acid in the solution, washing with deionized water twice, polishing, and ultrasonically cleaning the polished substrate in acetone, absolute ethyl alcohol and deionized water respectively;

secondly, preparing before coating: putting the substrate cleaned in the step one in N₂Drying with cold air under air flow, placing into a magnetron sputtering vacuum chamber, checking the air tightness of the vacuum chamber, vacuumizing until the vacuum degree in the vacuum chamber is lower than 1 × 10^-3Introducing argon gas, adjusting the air pressure in the vacuum chamber, starting a pulse power supply and a bias power supply, and carrying out sputtering cleaning and etching on the substrate;

thirdly, preparing a Ti-Si transition buffer layer: introducing argon into the vacuum chamber, adopting a Ti-Si alloy target as a cathode, and preparing a transition buffer layer by using the alloy target through plasma magnetron sputtering under the action of pulse and bias voltage;

fourthly, preparing a DLC thick film: introducing argon and propane, volatilizing toluene, conveying the toluene into a vacuum chamber, depositing and preparing a Pd element doped DLC thick film on a Ti-Si transition buffer layer in a mixed atmosphere of argon, propane and toluene by adopting a method of pulse and bias voltage cooperated with magnetron sputtering of a palladium target (Pd), wherein the doping proportion of the Pd is controlled by pulse power;

fifthly, aging and liquid nitrogen cooling: and according to the method of the fourth step, the prepared DLC thick film is cooled to room temperature, taken out of the vacuum chamber, aged for a period of time, put into liquid nitrogen and cooled for a moment, and taken out.

Preferably, the substrate in the first step may be any one of magnesium alloy, aluminum alloy, alloy steel or titanium alloy.

Preferably, the concentration of the oxalic acid, the citric acid, the sodium benzenesulfonate and the sodium bicarbonate in the step one is 5-40 wt%; and ultrasonically cleaning the substrate in acetone, absolute ethyl alcohol and deionized water for 10-30 min respectively, wherein the ultrasonic power is 100-200W.

Preferably, in the second step, the pressure of the vacuum chamber for etching and cleaning the substrate by the Ar ions is 0.5 Pa-1.5 Pa, the bias voltage of the substrate is-500V-1500V, the power of the pulse power supply is 300-500W, the duty ratio is 20-70%, the Ar flow is 15-100 sccm, and the etching and cleaning of the Ar ions are carried out for 5 min-30 min to obtain the substrate with a clean surface.

Preferably, the thickness of the Ti-Si transition buffer layer in the third step is 0.05-0.6 μm, the atomic percentage of Si element in the Ti-Si target is 5-95 at%, and the deposition time is 1-10 min.

Preferably, in the third step, the pulse power is 300-500W, the duty ratio is 20-70%, the bias voltage is-100 to-500V, the Ar flow is 15-100 sccm, and the working pressure is 0.5-1.5 Pa.

Preferably, the pulse power in the fourth step is 300-500W, the duty ratio is 20-70%, the bias voltage is-100 to-500V, the DLC thickness is 120-220 μm, and the deposition time is 4-7 h.

Preferably, in the fourth step, the flow rate of Ar is 15-100 sccm, the flow rate of propane is 50-200 sccm, the flow rate of toluene is 50-200 sccm, the working pressure is 1.0-2.5 Pa, the power of the pulse power supply for sputtering the Pd target is 50-300W, the duty ratio is 10-80%, the bias voltage is-50-200V, and the doping proportion of Pd is 10-50 wt%.

Preferably, in the fifth step, the aging time is 10-90 h, the aging temperature is 15-30 ℃, and the liquid nitrogen is cooled for 5-30 s.

Compared with the prior art, the invention has the advantages that:

1. the invention adopts the magnetron sputtering technology of pulse plus bias to prepare the Pd-doped DLC thick film on the surface of the metal material, breaks through the prior periodic film and greatly simplifies the operation and the flow.

2. Propane and toluene high-density gas is used as a mixed carbon source, the gas ionization rate is high, the plasma density and energy are high, the thick film deposition thickness is 120-220 mu m, the phenomena of breakage, wear-through and the like do not exist, and the capability of absolutely protecting a matrix is realized. The metal Pd of the silver white with the face-centered cubic structure is adopted as a doping element, so that the plasticity and the toughness of the thick film can be greatly improved, the frictional wear performance of the thick film is greatly improved, and the Pd doping proportion is controllable;

3. the aging is beneficial to releasing the stress of the thick film, the liquid nitrogen cooling greatly improves the hardness of the thick film, and the superhard effect is achieved;

4. the method is safe and reliable, green and pollution-free, high in production efficiency, simple in required equipment, convenient to operate, easy to realize and worthy of popularization.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is an SEM cross-sectional profile of a DLC thick film in example 1;

FIG. 2 is HRTEM and SAED electron diffraction images of the DLC thick film in example 1, with HRTEM on the left and SAED electron diffraction images on the right.

FIG. 3 is an acoustic emission curve of the bonding performance of the DLC thick film in example 1;

FIG. 4 is the electrochemical polarization curve of the DLC thick film in example 1;

FIG. 5 is a graph showing the friction coefficient of a DLC thick film in example 1.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings and examples, so that how to implement the technical means for solving the technical problems and achieving the technical effects of the present invention can be fully understood and implemented.

The first embodiment is as follows: the embodiment is a method for depositing a DLC thick film by using a high-density plasma composite carbon source, which comprises the following steps:

firstly, pretreatment of a substrate: grinding the matrix with metallographic abrasive paper of different meshes, cleaning in mixed solution of oxalic acid, citric acid and sodium benzenesulfonate, and adding NaHCO₃Neutralizing the solution, washing and polishing the solution by deionized water twice, and then respectively ultrasonically cleaning the solution in acetone, absolute ethyl alcohol and deionized water;

secondly, preparing before coating: putting the substrate cleaned in the step one in N₂Drying with cold air under air flow, placing in a magnetron sputtering vacuum chamber, and vacuumizingWhen the degree of vacuum is lower than 1X 10^-3After Pa, introducing argon gas, adjusting the air pressure in the vacuum chamber, starting a pulse and bias power supply, and carrying out sputtering cleaning and etching on the substrate for 5-30 min;

thirdly, preparing a Ti-Si transition buffer layer: introducing argon, and sputtering a Ti-Si alloy target by adopting a pulse and bias mixed magnetron sputtering method to prepare a Ti-Si transition buffer layer;

fourthly, preparing a DLC thick film: introducing argon, propane and toluene, and depositing the Pd-doped DLC thick film by sputtering a Pd target in a composite carbon source atmosphere by adopting a pulse and bias mixed magnetron sputtering method;

fifthly, aging and liquid nitrogen cooling: and D, cooling the DLC thick film prepared in the step four, taking the DLC thick film out of the vacuum chamber, aging for a period of time, and cooling in liquid nitrogen for a while.

The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the matrix in the first step comprises various metal materials such as magnesium alloy, aluminum alloy, titanium alloy, steel and the like. The mesh number of the metallographic abrasive paper for grinding is 280#, 500#, 800#, 1000#, 1500#, 2000#, 2500#, 3000#, 3500#, 4000#, and 5000 #. The rest is the same as the first embodiment.

The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: the polishing in the first step is as follows: for the polished substrate, Al with the granularity of 0.5-2.5 mu m₂O₃And (5) polishing under the action of the polishing paste. In the step one, the ultrasonic cleaning time is 10-30 min, and the ultrasonic power is 100-200W. Oxalic acid, citric acid, sodium benzenesulfonate and NaHCO₃The concentration is 5-40%, and the cleaning time is 10-30 min. The other is the same as in one or both of the first and second embodiments.

The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: in the second step, the power of the pulse power supply is 300-500W, the duty ratio is 20-70%, and the bias voltage is-500V-1500V. The others are the same as in one of the first to third embodiments.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: in the second step, the working pressure is 0.5 to 1.5Pa, the Ar flow is 15 to 100sccm, and the sputtering time is 5 to 30 min. The other is the same as one of the first to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: the concrete operation of the Ti-Si transition buffer layer in the step three is as follows: firstly, fixing a cleaned substrate on a sample frame, vacuumizing to a preset value, introducing argon, opening a flow valve switch, sputtering a Ti-Si alloy target (Si atomic percentage is 5-95%) under the combined action of pulse (300-500W, 20-70% duty ratio) and bias voltage (-100-500V), and depositing a Ti-Si transition buffer layer on the substrate, wherein the working pressure is 0.5-1.5 Pa. The other is the same as one of the first to fifth embodiments.

The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: in the third step, the thickness of the Ti-Si transition buffer layer is 0.05-0.6 mu m, the Ar flow is 15-100 sccm, the deposition time is 1-10 min, and the background vacuum degree is 1 multiplied by 10^-4～5×10^-3. The other is the same as one of the first to ninth embodiments.

The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: in the fourth step, the purity of the argon is 99.00-99.999%, the flow rate is 15-100 sccm, the purity of the propane and the toluene is 99.00-99.99%, and the flow rate is 50-200 sccm. The pulse power is 100-400W, the duty ratio is 10-80%, the bias voltage is-50 to-200V, and the working air pressure is 1.0-2.5 Pa. The other is the same as one of the first to seventh embodiments.

The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: in the fourth step, the deposition time of DLC film is 4-7 h, the thickness is 120-220 μm, and the Pd doping ratio is 10-50 wt%. The rest is the same as the first to eighth embodiments.

The detailed implementation mode is ten: the present embodiment differs from one of the first to ninth embodiments in that: and the aging time in the step five is 10-90 h, and the aging can be carried out at room temperature, and the temperature can be 15-35 ℃. And cooling the film for 5-30 s by using liquid nitrogen to obtain the superhard wear-resistant DLC non-periodic thick film. The other is the same as one of the first to ninth embodiments.

The following examples are given to illustrate the present invention, and the following examples are carried out on the premise of the technical solution of the present invention, and give detailed embodiments and specific procedures, but the scope of the present invention is not limited to the following examples.

Example 1:

this example shows a method for depositing DLC thick film by high density plasma composite carbon source

The method comprises the following steps:

firstly, pretreatment of a substrate: grinding magnesium alloy matrix with size of 20mm × 20mm × 3mm with metallographic abrasive paper step by step, cleaning in mixed solution of oxalic acid, citric acid and sodium benzenesulfonate, and washing with NaHCO₃Soaking in solution for neutralization, washing with deionized water twice, and adding Al₂O₃Polishing under the action of the polishing paste to obtain a substrate with a smooth surface. And then ultrasonically cleaning the substrate in acetone, absolute ethyl alcohol and deionized water respectively, wherein the ultrasonic cleaning time is 20min, and the ultrasonic power is 120W. Wherein the element content of the matrix is as follows: al: 3.0911 wt.%, Zn: 0.7862 wt.%, Mn: 0.2863 wt.%, Mg: and (4) the balance. The grinding is sequentially performed by using 280#, 500#, 800#, 1000#, 1500#, 2000#, 2500#, 3000#, 3500#, 4000#, 4500# and 5000# metallographic abrasive paper.

Secondly, preparation before film coating: in N₂Blowing the mixture with cold air under air flow, and putting the mixture into a magnetron sputtering vacuum chamber. The Pd target is well installed, the cleaned substrate is fixed on a sample rack, the distance between the target material and the sample rack is adjusted to be 60mm, and then the top cover of the vacuum chamber is closed and the air tightness of the vacuum chamber is checked. Then starting a mechanical pump to pump vacuum, and starting a molecular pump to further pump vacuum when the vacuum degree is lower than 10Pa until the background vacuum degree in the vacuum chamber is less than or equal to 1 multiplied by 10^-3Pa. Introducing argon gas and regulating the air pressure in the vacuum chamber, then starting the high-power pulse power supply and the bias power supply, sputtering and cleaning and etching the magnesium alloy substrate, thus the combination property of the film and the substrate can be improved.

Thirdly, preparing a Ti-Si transition buffer layer: introducing argon gas with the purity of 99.99 percent and the flow of 60sccm, and preparing a Ti-Si transition buffer layer on the surface of the substrate cleaned by the ion etching by utilizing the pulse and bias magnetron sputtering technology to obtain the Ti-Si transition buffer layer-substrate.

Fourthly, preparing a DLC thick film: introducing argon, propane and toluene, sputtering a high-purity Pd metal target by using a pulse and bias composite magnetron sputtering technology in a high-density carbon source atmosphere to prepare a Pd-doped DLC thick film, and obtaining the DLC thick film-Ti-Si transition buffer layer-substrate.

Fifthly, liquid nitrogen cooling: after the preparation is finished, the DLC thick film is aged for 60 hours at the room temperature of 25 ℃, and then is cooled for 10 seconds by liquid nitrogen, thus finishing the preparation of the DLC amorphous non-periodic thick film on the surface of the magnesium alloy substrate.

Step one, the concentration of the oxalic acid, the citric acid and the sodium benzenesulfonate in the mixed solution is 10 percent, and NaHCO is adopted₃10% by mass of the solution, Al₂O₃The particle size of the polishing paste was 1.5. mu.m.

And step two, the power of the pulse power supply is 450W, the duty ratio is 60%, and the bias voltage is-1000V. The flow rate of Ar is 60sccm, the working pressure is 1.0Pa, and the pre-sputtering time is 20 min.

And step three, the power of the pulse power supply is 450W, the duty ratio is 60%, and the bias voltage is-200V. The flow rate of Ar is 60sccm, the working pressure is 1.0Pa, the sputtering time is 5min, and the thickness of the Ti-Si transition buffer layer is 200 nm.

And step four, the purity of the Ar gas is 99.99 percent, and the flow rate is 60 sccm. The power of the pulse power supply is 450W, the duty ratio is 60 percent, and the bias voltage is-200V. The working pressure is 2.0Pa, and the deposition time is 5 h.

And the purity of the propane and the toluene in the step four is 99.99 percent, and the flow rate is 150 sccm. The purity of the Pd metal target is 99.9 percent, the Pd doping proportion is 30 percent, and the thickness of the DLC thick film is 157.2 mu m.

The liquid nitrogen cooling operation in the fifth step is as follows: and closing all gas paths, closing all power supplies, taking out the thick film after cooling, aging at room temperature for 60h, and putting the thick film into liquid nitrogen for cooling for 10 s.

The method adopts the magnetron sputtering technology of high-power pulse and bias voltage, has high preparation efficiency, large film thickness, good performance, economy and practicality, and is an amorphous aperiodic wear-resistant thick film. Ti-Si is adopted as a buffer transition layer, so that the problem of poor bonding force between a substrate and a film caused by thermal physical property parameter difference is solved, and the film/substrate bonding performance is improved. The Pd element is doped in the DLC thick film, so that the toughness can be obviously improved, the friction and wear resistance of the DLC can be further improved, and a matrix can be effectively protected. The amorphous structure of DLC eliminates the columnar crystal structure in the traditional PVD method, reduces the channel of the external corrosive ions invading the matrix, and obviously improves the corrosion resistance. Moreover, the amorphous carbon has good lubricating effect, and is very helpful for improving the corrosion resistance and the wear resistance of the magnesium alloy matrix.

FIG. 1 is the SEM cross-sectional morphology of a thick film of DLC. As can be seen from FIG. 1, the thick film had a uniform thickness and a dense structure, and the thickness of the deposited film was 157.2 μm for 5 hours.

FIG. 2 is HRTEM observation of a DLC thick film. The observation of an F20 transmission electron microscope shows that the DLC film prepared by the method has an amorphous carbon structure, and the DLC thick film prepared by the embodiment is proved to be a high-quality material.

FIG. 3 is an adhesion acoustic emission curve of a DLC thick film. As can be seen from FIG. 3, the DLC thick film prepared by the method of the present invention has a film-based bonding strength of more than 45N and a bonding strength of 157.2 μm thick film.

FIG. 4 is an electrochemical polarization curve of DLC thick films tested in 3.5% NaCl solution. As can be seen from FIG. 4, the thick DLC film prepared by the method of the present invention had an etching potential of-0.565V and an etching current density of 5.82X 10^-8A/cm²It is proved that the DLC thick film has excellent corrosion resistance.

FIG. 5 is a graph showing the coefficient of friction of a DLC thick film at room temperature and 30% relative humidity. As can be seen from FIG. 5, the DLC thick film has a small coefficient of friction, less than 0.035, and exhibits good wear resistance.

The experiments prove that the method for depositing the DLC thick film by the high-density plasma composite carbon source is a method for depositing the DLC thick film.

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiments, and the specific structure thereof is allowed to vary. All changes which come within the scope of the invention as defined by the independent claims are intended to be embraced therein.

Claims

1. A method for depositing a DLC thick film by using a high-density plasma composite carbon source is characterized by comprising the following steps: the method comprises the following steps:

2. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: the substrate in the first step can be any one metal of magnesium alloy, aluminum alloy, alloy steel or titanium alloy.

3. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: the concentration of oxalic acid, citric acid, sodium benzenesulfonate and sodium bicarbonate in the step one is 5-40 wt%; and ultrasonically cleaning the substrate in acetone, absolute ethyl alcohol and deionized water for 10-30 min respectively, wherein the ultrasonic power is 100-200W.

4. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: in the second step, the pressure of the vacuum chamber for etching and cleaning the substrate by the Ar ions is 0.5 Pa-1.5 Pa, the bias voltage of the substrate is-500V-1500V, the power of the pulse power supply is 300-500W, the duty ratio is 20-70%, the Ar flow is 15-100 sccm, and the etching and cleaning of the Ar ions are carried out for 5 min-30 min to obtain the substrate with a clean surface.

5. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: in the third step, the thickness of the Ti-Si transition buffer layer is 0.05-0.6 mu m, the atomic percentage of Si element in the Ti-Si target is 5-95 at%, and the deposition time is 1-10 min.

6. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: in the third step, the pulse power is 300-500W, the duty ratio is 20-70%, the bias voltage is-100 to-500V, the Ar flow is 15-100 sccm, and the working pressure is 0.5-1.5 Pa.

7. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: in the fourth step, the pulse power is 300-500W, the duty ratio is 20-70%, the bias voltage is-100 to-500V, the DLC thickness is 120-220 μm, and the deposition time is 4-7 h.

8. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: in the fourth step, the flow rate of Ar is 15-100 sccm, the flow rate of propane is 50-200 sccm, the flow rate of toluene is 50-200 sccm, the working pressure is 1.0-2.5 Pa, the power of the pulse power supply for sputtering the Pd target is 50-300W, the duty ratio is 10-80%, the bias voltage is-50-200V, and the doping proportion of Pd is 10-50 wt%.

9. The method of claim 1, wherein the high-density plasma composite carbon source is used for depositing DLC thick film, and the method comprises the following steps: and in the fifth step, the aging time is 10-90 h, the aging temperature is 15-30 ℃, and the liquid nitrogen is cooled for 5-30 s.