CN1172019C - Process of direct deposition of diamond-like carbon film by dual ion beams - Google Patents

Abstract

The present invention relates to a technology for directly depositing a diamond-like film by using dual ion beams. The technology is characterized in that a mixing interface is manufactured by the bombardment of the dual ion beams, and the low energy ion beam directly deposits a diamond-like film. The low energy carbonaceous ion beam directly deposits a diamond-like film layer, and simultaneously, the moderate energy Ar<+> ion beam is used for bombarding the film layer. Acrbonic ions are injected into the enough depth of the surface of a basal body to mix film base atoms to form a blurring interface with high film adhesive strength. In the processes, the beam current of the two ion beams are changed alternately. After the interface is mixed for certain time, the bombardment of the moderate energy ion beam is stopped, and the low energy carbonaceous ion beam continuously and directly deposits the diamond-like film. The technology enhances the bonding strength of the diamond-like film through the increase of the injecting depth of carbon in the surface of the substrate and the reduction of film stress, and has the advantages of easy and simple operation, stable quality, industrial production and wide application prospect.

Description

Process of direct deposition of diamond-like carbon film by dual ion beams

Technical field: the present invention relates to a synthesis process of a diamond-like film, especially a process for synthesizing a diamond-like film with an energetic ion beam.

Existing technology: Diamond-like carbon (DLC) has excellent properties such as high hardness, low friction coefficient, good thermal conductivity, and good chemical stability, and the deposition temperature is relatively low (<300°C), the deposition area is large, and the film surface is smooth and flat. Ideal coating material for surface modification of materials. At present, the process methods for synthesizing diamond-like films can be generally divided into energetic ion bombardment assisted deposition and non-energetic ion bombardment assisted deposition. Ion Beam Direct Deposition (IBD). Ion beam assisted deposition (IBAD) diamond-like film technology is coated under ion beam assisted bombardment. At present, there are two main coating methods: one is to use electron gun to evaporate solid carbon source coating; the other is to use ion beam sputtering graphite Target coating (called dual ion beam sputter deposition, DIBS). Although the ion beam assisted deposition technology can improve the bonding strength of the diamond-like film compared with other deposition methods, there are still some difficulties in making it work under strong friction conditions. It mainly comes from two aspects. One is the existing ion beam It is very difficult to prepare diamond-like film by the typical process of assisted deposition, because graphite has a layered structure, and it is easy to form large flake particles (atomic clusters) during sputtering or evaporation. Under ion beam assisted bombardment, if the process conditions are not suitable, C-C The key structure is difficult to change, resulting in the poor quality of the synthesized carbon film, and its process is difficult to meet the requirements of industrial production; on the other hand, there is a lot of stress when the high hardness diamond-like film is combined with steel and other workpieces. The influence of the synthesis process and the structure of the film has become the main reason for the weakening of the bond strength of the diamond-like film. Experimental studies have shown that in order to avoid the influence of stress on the friction and wear of the diamond-like film, the diamond-like film prepared by ion beam assisted deposition The optimal thickness for surface modification is only 0.5 μm, a limitation that makes it difficult for DLC to be applied in the service environment of mechanical engineering wear-resistant parts subject to large wear loads. The ion beam direct deposition (IBD) diamond-like film is a technology that uses a carbon-containing gas-phase ion beam with a certain energy to directly deposit a carbon film. The quality of the synthesized film is high and stable. At the same time, the grown film was also bombarded, but the effect of the bombardment injection was poor, and the bonding strength was lower than that of the ion beam assisted deposition film.

Summary of the invention: The purpose of the present invention is to provide a dual-ion beam direct deposition of diamond-like film that can significantly improve the bonding strength and quality stability of the diamond-like film, meet the requirements of mechanical strong friction work, simplify the process conditions, and adapt to the requirements of industrial production. craft.

The technical scheme of the invention is: bombarding with double ion beams to make a mixed interface, and low-energy ion beams to directly deposit a diamond-like film. The dual ion beams used for bombarding and making the mixed interface are low-energy carbon-containing ion beams and medium-energy Ar ⁺ ion beams, and the low-energy ion beams used for direct deposition of diamond-like films are low-energy carbon-containing ion beams.

A further feature of the present invention is that a low-energy ion beam is used to directly deposit the diamond-like film layer, and at the same time, a medium-energy Ar ⁺ ion beam is used to bombard the film layer.

In the present invention, a low-energy carbon-containing ion beam of 200-1000eV is used to directly deposit a diamond-like film layer, and at the same time, a medium-energy Ar ⁺ ion beam of 20k-35keV is used to bombard the film layer, and carbon ions are implanted into the surface layer of the substrate to a sufficient depth to mix the film substrate Atoms form a fuzzy interface that can significantly improve the bonding strength of the film. During this process, the two ion beams alternately change. After the interface is mixed for a certain period of time, the medium-energy ion beam bombardment is stopped, and the low-energy carbon-containing ion beam continues to directly deposit the diamond-like film. , maintaining the continuity of the interfacial mixing and coating process, the operation is simple, and the quality of the diamond-like carbon film is stable.

Dual ion beam bombardment hybrid technology is not only an ion beam assisted coating process, but also a dynamic recoil ion implantation process. Energy-carrying carbon ions pass through the auxiliary bombardment of medium-energy Ar ⁺ , and the implantation depth of carbon ions increases due to the accelerated diffusion of radiation and ion energy exchange. And the lattice matching changes, thereby slowing down the interfacial stress of the film base. Therefore, the dual ion beam bombardment mixing technique enhances the bond strength of the DLC film by increasing the depth of carbon implantation into the surface layer of the substrate and reducing the film stress.

Concrete process of the present invention is:

200～ 200～ 200～ 200～ 200～ 200～

...

Low energy CH _n ⁺ 1000eV/25～ 1000eV/10～ 1000eV/25～ 1000eV/10～ 1000eV/25～ 1000eV/10～

...

40mA 20mA 40mA 20mA 40mA 20mA

20～ 20～ 20～ 20～ 20～ 20～

Medium Energy Ar ⁺ 0

                                                                                   

Time (min) 10 10 10 10 10 10 60～300

Function Deposition of diamond-like film while interfacial mixing Deposition of diamond-like film

The process flow of the present invention is as follows: firstly, pre-treat the surface of the substrate by grinding, polishing, cleaning and drying, etc., bombard and clean the surface of the workpiece to be treated with a low-energy large beam current Ar ⁺ ion beam, and directly deposit a diamond-like carbon film layer with a low-energy carbon-containing ion beam , at the same time bombard the film layer with a medium-energy Ar ⁺ ion beam. After a certain period of time, stop the bombardment of the medium-energy Ar ⁺ ion beam and continue to directly deposit the diamond-like film with a low-energy carbon-containing ion beam; finally perform a performance test on the film layer. The entire process Finished, the workpiece is ready for production.

The invention can modify the surface of many materials including steel, cemented carbide and the like with a diamond-like film coating. Before depositing the diamond-like film, the surface of the substrate must be ground and polished, cleaned and dried; the equipment used to implement the present invention is a commonly used ion beam assisted deposition (IBAD) equipment, and the background vacuum is 5 × 10 ^{- 5} Pa, the working pressure is (1～2)×10 ^-2 Pa, the low-energy ion source uses high-purity CH ₄ as the gas source to generate low-energy CH _n ⁺ ion beams, and the medium-energy ion source uses high-purity Ar as the gas source to generate medium Ar ⁺ ion beam can be used; in order to ensure uniform coating and substrate temperature below 150°C, the sample stage is water-cooled and rotated.

Implement the used ion beam assisted deposition (IBAD) equipment of the present invention, generally be equipped with three ion sources, each ion source effect is as follows: Ion Source Energy Range Beam Current (mA) Effect (ev) The role of each ion source in implementing the present invention Working gas function Sputtering source 0～4k 0～150 Sputtering solid target coating Bombardment cleaning workpiece Low energy bombardment source 50～1500 10～120 Surface, or bombardment film layer, or ion beam direct coating medium energy bombardment source 0～40k 0～5 bombardment film Do not use Ar bombardment to clean the CH ₄ coating on the surface of the workpiece. Ar bombardment film layer

According to the above table, the present invention can also be implemented on special equipment, that is, the special equipment only needs to be equipped with two ion sources, a low energy ion source is used to deposit diamond-like film; a medium energy ion source is used to bombard the film layer, carbon ion Inject into the surface layer of the substrate to a sufficient depth to mix the film-based atoms to form a fuzzy interface that can significantly improve the bond strength of the film.

Since the synthetic diamond-like film of the present invention is completed at normal temperature, the diamond-like coating can be applied to any workpiece that needs friction reduction, wear resistance and corrosion resistance. However, the application of diamond-like film is restricted by two factors, one is the bonding strength of the film, and the other is the cost factor. As a high-tech, direct deposition of diamond-like film by dual ion beams is not suitable for application on ordinary workpieces. Its mechanical application The scope is preferred for aerospace bearings, key parts of automobiles that are prone to abrasion (such as pistons and piston rings, valve lifters and guides, drive gears, etc.), steam turbine blades, and precision machining tools. The global consumption of these parts is huge every year, and most of them work under friction, wear, corrosion and other working conditions, and some also work under dry friction conditions. The diamond-like film has an irreplaceable advantage in working under such working conditions. .

The main advantages of the present invention are:

(1) Using dual ion beam bombardment mixing technology, carbon ions can be implanted into the surface of the substrate to a depth of more than 200nm, which is much larger than the tens of nanometers of ion beam assisted deposition and the tens of nanometers of ion beam direct deposition. At the same time, due to the interfacial mixing effect, The stress of the diamond-like carbon film is slowed down, thereby significantly improving the bonding strength of the diamond-like carbon film. The scratch test shows that the critical load of film peeling is greater than 50N, even exceeding the test limit of the instrument (100N), which is greater than the result of ion beam assisted deposition;

(2) Due to the sufficient depth of carbon injection into the surface layer of the substrate, the hardness of the substrate is improved, forming a strong support for the film, thereby improving the composite hardness of the diamond-like film, and the microhardness HV of the film can reach 25-35GPa, which is better than that of ion beam assisted deposition. 18～35GPa and 20～30GPa directly deposited by ion beam;

(3) Since the diamond-like carbon film is directly deposited by CH _n ⁺ , the process is easy to operate, the film quality is stable, and it can be adapted to industrial production;

(4) In addition to the mixed interface, only one low-energy ion source is used in the process of depositing the diamond-like film, which can reduce the production cost compared with the conventional ion beam-assisted deposition process that always uses two ion sources to deposit the diamond-like film.

The comprehensive comparison of the three processes is as follows: The main technical and economic indicators Ion beam assisted deposition of the present invention (dual ion beam direct deposition sub-beam sputtering deposition) Mixed interface layer depth stress DLC bond strength HV (40Cr substrate, ballast 0.15N) DLC quality stability repeatability deposition efficiency cost Hundreds of nanometers Tens of nanometers Tens of nanometers Small Medium Large High High Low 25～35GPa 18～35GPa 20～30GPa Stable Unstable Stable Good General Good High High High High Low High Low

BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a process flow diagram of the present invention.

The specific embodiment: as shown in Figure 1, the technological process of the present invention is:

(1) Substrate pretreatment: perform pretreatments such as grinding, polishing, cleaning and drying on the substrate surface;

(2) Ion beam bombardment cleaning on the surface of the substrate: use low-energy large beam current Ar ⁺ ion beam bombardment to clean the surface of the workpiece to be treated;

(3) Double ion beam bombardment to make a mixed interface: a low-energy carbon-containing ion beam is used to directly deposit a diamond-like film layer, and a medium-energy Ar ⁺ ion beam is used to bombard the film layer.

(4) Stop the bombardment of the medium-energy ion beam, and directly deposit the diamond-like carbon film with the low-energy ion beam: stop the bombardment of the medium-energy Ar ⁺ ion beam, and continue to directly deposit the diamond-like carbon film with the low-energy carbon-containing ion beam;

(5) Detection and application: perform performance test on the film layer, and apply the workpiece to production.

Embodiment 1, diamond-like film coating tool production

Process flow: commercially available hard alloy YG6 tool (tool model is C116) → tool surface polishing and grinding → edge cutting (blade is ground according to requirements, the radius of the knife tip arc is 1.2mm) → acetone ultrasonic cleaning → drying → loading On the sample stage in the vacuum chamber of the ion beam assisted deposition device (the sample stage is water-cooled and rotated) → use 1000eV, 100mA low-energy Ar ⁺ ion beam bombardment to clean the tool surface for 20min → double ion beam bombardment to make a mixed interface (see the table below for the specific process) → Stop the medium-energy ion beam bombardment, continue to use low-energy CH _n ⁺ ion beam (energy 350eV, beam current 25mA) to directly deposit diamond-like film for 5 hours → trial

Low energy CH _n ⁺ 350eV/25mA 350eV/10mA 350eV/25mA 350eV/10mA 350eV/25mA 350eV/10mA

Zhongneng Ar ⁺ 30keV/1mA 30keV/2mA 30keV/1mA 30keV/2mA 30keV/1mA 30keV/2mA

Time(min) 10 10 10 10 10 10

Application effect: A diamond-like film-coated tool was successfully produced, and the application test of turning the outer circle of 6105Q-1C piston was carried out on a CNC "soft profiling" profiling machine tool in a certain factory. The cutting workpiece material was ZL109 (containing Si11-13% Aluminum alloy), the nominal diameter of the piston outer circle is Φ105mm, the machine speed is 1500r/min, the cutting depth is 0.15-0.20mm, intermittent dry cutting. The surface roughness, size and shape accuracy of the pistons processed by the test tools all meet the processing requirements, and a total of 4,500 pistons are processed. Due to the development of the automobile industry, the surface quality, dimensional accuracy and shape accuracy of the piston are required to be improved. The surface roughness Ra≤1.6μm, the dimensional accuracy ±0.01mm, and the processing surface of the 61050-1C piston outer circle is a convex and elliptical surface. Cemented carbide tools are not suitable for high-speed cutting due to their high cutting resistance and easy wear, and their service life is low and machining accuracy cannot be guaranteed. Therefore, cemented carbide tools are no longer suitable for processing the outer circle of such pistons. When the diamond-like film is deposited on the cemented carbide tool, due to the wear-resistant and anti-friction effects of diamond-like, its cutting resistance decreases, and the wear rate during the cutting process decreases, thereby ensuring the size and shape accuracy of the cutting workpiece. From this point of view, the significance of coating diamond-like film on cemented carbide tools is not only the improvement of life, but also the problem of whether it can process high-quality pistons. However, for some pistons with low surface quality requirements and a perfect circle, cemented carbide can still be used for processing. Each knife can process 1500 to 2000 pistons with a perfect outer circle (the piston material is ZL109). The cutting tool for turning pistons commonly used in factories is polycrystalline diamond cutting tool (PCD). Each knife (made of materials imported from Britain and the United States) can process 6,000 to 8,000 pistons of 6105Q-1C, but the price of the knife is relatively high, about 200~ 400 yuan/piece, which is 3 to 5 times that of diamond-like coated tools.

Embodiment two, 40Cr steel surface diamond-like film coating modification

Process flow: Quenching and tempering 40Cr steel → cutting into several cylindrical samples with a diameter of 24 mm and a height of 7.8 mm → grinding and polishing the end face → ultrasonic cleaning with acetone → drying → loading onto the sample stage in the vacuum chamber of the ion beam assisted deposition device (The sample stage is water-cooled and rotated)→Use 1000eV, 60mA low-energy Ar ⁺ ion beam bombardment to clean the sample surface for 10min→dual ion beam bombardment to make a mixed interface (see the table below for the specific process)→Stop the medium-energy ion beam bombardment and continue to use low-energy ion beam CH _n ⁺ ion beam (energy 400eV, beam current 25mA) direct deposition of diamond-like film for 3 hours→performance test

Low energy CH _n ⁺ 400eV/25mA 400eV/10mA 400eV/25mA 400eV/10mA 400eV/25mA 400eV/10mA

Medium energy Ar ⁺ 25keV/1mA 25keV/2mA 25keV/1mA 25keV/2mA 25keV/1mA 25keV/2mA

Time(min) 10 10 10 10 10 10

Performance test results:

(1) The microhardness HV is 29.93Gpa (2993kg/mm ² ) (test conditions: ballast 15g, holding time 20s);

(2) The bonding strength of the film is high, and the scratch test shows that the critical load of film peeling is greater than 100N (exceeding the test limit of the instrument);

(3) Friction and wear tests show that the wear amount of the diamond-like film coating is 1/274 of the 40Cr steel substrate, and the anti-wear index AWN is 1.52 times that of the 40Cr steel substrate;

Embodiment three, 2Cr13 stainless steel surface diamond-like film coating modification

Process flow: 2Cr13 stainless steel → cut into several cylindrical samples with a diameter of 20 mm and a height of 10 mm → end face grinding and polishing → ultrasonic cleaning with acetone → drying → loading onto the sample stage in the vacuum chamber of the ion beam assisted deposition device (the sample stage is water-cooled and rotate) → use 1000eV, 60mA low-energy Ar ⁺ ion beam bombardment to clean the surface of the sample for 10 minutes → double ion beam bombardment to make a mixed interface (see the table below for the specific process) → stop medium-energy ion beam bombardment, and continue to use low-energy CH _n ⁺ ion beam (energy 350eV, beam current 25mA) direct deposition of diamond-like film for 2 hours → corrosion resistance test

Low energy CH _n ⁺ 350eV/25mA 350eV/10mA 350eV/25mA 350eV/10mA 350eV/25mA 350eV/10mA

Zhongneng Ar ₊ 25keV/1mA 25keV/2mA 25keV/1mA 25keV/2mA 25keV/1mA 25kV/2mA

Time (min) 10 10 10 10 10 10

Corrosion resistance test results: The sample was soaked in 3.5% NaCl solution for 14 hours, and the weight loss test showed that the corrosion rate was 0.004g/m ² ·h, far lower than the corrosion rate of the substrate 0.51g/m ² ·h.

Claims (5)

1. A process for directly depositing a diamond-like carbon film with dual ion beams, characterized in that it uses 200-1000eV low-energy carbon-containing ion beams and 20k-35keV medium-energy Ar ⁺ ion beams to bombard a mixed interface, and uses 200-1000eV low-energy Carbon-containing ion beams directly deposit diamond-like carbon films. 2. The process for direct deposition of diamond-like carbon film by dual ion beams according to claim 1, characterized in that the diamond-like carbon film layer is directly deposited with a low-energy carbon-containing ion beam of 200-1000 eV, and at the same time, a medium-energy Ar ⁺ of 20k-35keV is used The ion beam bombards the membrane layer. 3. The process for directly depositing a diamond-like carbon film by dual ion beams according to claim 1, characterized in that the diamond-like carbon film layer is directly deposited by a low-energy carbon-containing ion beam of 200-1000 eV, and at the same time, a medium-energy Ar ⁺ of 20k-35keV is used The ion beam bombards the film layer, and the two ion beam currents alternately change during this process. After the interface is mixed for a certain period of time, the medium-energy Ar ⁺ ion beam bombardment of 20k-35keV is stopped, and the low-energy carbon-containing ion beam of 200-1000eV continues to deposit directly. diamond-like film. 4. The process for directly depositing a diamond-like carbon film by dual ion beams according to claim 1, characterized in that its specific process is: 200～ 200～ 200～ 200～ 200～ 200～ 200～ Low energy CH _n ⁺ 1000eV/25～ 1000eV/10～ 1000eV/25～ 1000eV/10～ 1000eV/25～ 1000eV/10～ 1000eV/25～ 40mA 20mA 40mA 20mA 40mA 20mA 40mA Medium energy Ar ⁺ 20～35keV/1mA 20～35keV/2mA 20～35keV/1mA 20～35keV/2mA 20～35keV/1mA 20～35keV/2mA 0 Time (min) 10 10 10 10 10 10 10 60～300                                 Function Interfacial mixing while depositing diamond-like carbon film Stone Membrane 5. The process for directly depositing diamond-like carbon films by dual ion beams according to claim 1 or 2 or 3 or 4, characterized in that the process flow is as follows: (1) Substrate pretreatment: ground and polish the substrate surface, clean and dry pretreatment; (2) Ion beam bombardment cleaning of the substrate surface: Use 200-1000eV low-energy and large-current ion beam bombardment to clean the surface of the workpiece to be treated; (3) Double ion beam bombardment to make a mixed interface: use 200-1000eV low-energy carbon-containing ion beams to directly deposit the diamond-like film layer, and use 20k-35keV medium-energy Ar ⁺ ion beams to bombard the film layer. (4) 200-1000eV low-energy ion beam directly deposits diamond-like carbon film: stop the bombardment of 20k-35keV medium-energy Ar ⁺ ion beam, and continue to directly deposit diamond-like carbon film with 200-1000eV low-energy carbon-containing ion beam; (5) Detection and application: perform performance test on the film layer, and apply the workpiece to production.

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