CN113201720B - Method for constructing high-bearing low-friction rubber surface through in-situ ion co-injection - Google Patents

Abstract

The invention relates to a method for constructing a high-bearing high-bonding low-friction rubber surface by in-situ ion co-injection, which comprises the steps of taking a metal target and a carbon target as ion co-injection materials, adopting a vacuum arc ion source, in-situ co-injecting metal and carbon elements into the rubber surface as a bearing layer, and then injecting carbon elements, thereby obtaining the high-bearing low-friction rubber surface. The method adopts the in-situ ion co-injection technology, so that the risk of interlayer peeling existing in the deposition of the bearing layer on the surface of the rubber is avoided; the ion concentration is gradually changed during injection, so that the natural transition from the mechanical hardness of the rubber soft substrate to the hard carbon film is successfully realized, and the risk of fragmentation and stripping of the film under ultrahigh load is avoided; only carbon elements are injected in the later period, so that perfect lattice matching between the carbon film and the bearing layer is realized, and the high bonding strength of the film is ensured. The process is easy to control, the operability is strong, the obtained rubber surface has the characteristics of high bearing capacity, high combination, low friction and the like, and the large-area industrial application is easy to realize.

Description

A method for constructing high-load-bearing low-friction rubber surfaces by in-situ ion co-implantation

technical field

The invention relates to a method for preparing a high-loading and low-friction rubber surface, in particular to a method for constructing a high-loading and low-friction rubber surface by in-situ ion co-implantation, belonging to the field of solid lubricating materials and polymer tribology.

Background technique

Rubber has good compressibility and resilience, good air tightness, solvent resistance and other properties, and is widely used in aerospace, petrochemical, automotive and other fields. However, when rubber is used as a moving part, that is, when the rubber and the hard pair are paired with a very high friction coefficient (µ>1), the frictional heat generated by the high friction can easily lead to softening of the rubber seal and rapid wear failure, making the high-pressure seal The medium leaks from the damaged part and the seal fails, which affects the safe and reliable service of the equipment. Therefore, to solve the problem of wear failure of rubber seals, we must start with reducing friction.

Carbon film has low adhesion characteristics with steel counterpart, low deposition temperature (deposition temperature ≤ 100 ℃, no fatal damage to nitrile rubber matrix), controllable composition and mechanical strength, and variable structure (such as multi-micro-nano structure) , multi-element doping, etc.), low friction and wear and other excellent properties, so it is an ideal coating to achieve low friction on the rubber surface. However, rubber is a soft substrate, and carbon film is a hard film. Ensuring that the hard film on the soft surface will not be mechanically broken and peeled off under ultra-high load is the key to achieving low friction on the rubber surface. The traditional method to improve the load-bearing capacity is to deposit a hard intermediate layer on the rubber surface, but there is still a layer-to-layer interface between it and the rubber substrate, that is, there is still a risk of chipping and spalling under ultra-high load. Therefore, how to construct the bearing layer in situ on the rubber surface is the top priority to ensure the mechanical cracking and peeling of the carbon film under ultra-high load.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for constructing a high-load-low-friction rubber surface by in-situ ion co-implantation in view of the defect of poor bearing capacity of the existing carbon film on the rubber surface under ultra-high load.

1. Construction of high load-bearing and low-friction rubber surface

The construction of the high-loading and low-friction rubber surface of the present invention is to use metal target and carbon target as ion co-implantation materials, and use a vacuum arc ion source to co-inject metal and carbon elements into the cleaned rubber surface as a bearing layer in situ. , and then use magnetron sputtering to deposit a carbon film on the carrier layer to obtain a high-load-bearing and low-friction rubber surface.

The rubber base is one of nitrile rubber, fluorine rubber and silicone rubber, the surface roughness of the rubber is less than or equal to 200 nm, and the thickness of the rubber is 3-5 mm.

The carrier layer injection deposition: evacuate to 1×10 ^-6 Pa; adjust the carbon target current to 45-60 A, the duty cycle to be 40-50%, and the beam density to be 0.48-0.64A/100cm ² ·s, The injection time was 480s; at the same time, the metal target current was gradually increased from 0A to 40A, the duty cycle was 50%, and the beam density was gradually increased from 0A to 0.42A/100cm ² ·s, and the injection time was 360s; the accelerating voltage was controlled to -20 ~-30kV, frequency 1~3 Hz. The metal target is one of Ti, Cr, and W targets. The carbon target is a graphite target.

The carbon film deposited by magnetron sputtering: using a graphite target, the target base distance is 8~12cm, the target current is 3A, the flow rate of argon gas is 45~60sccm, the flow ratio of Ar/CH ₄ is 1.5:1, and the substrate bias voltage It is -700V, the air pressure is 1~1.5Pa, the duty cycle is 40~45%, the frequency is 60~70KHz, and the deposition time is 120~150min.

FIG. 1 is a schematic structural diagram of the low friction rubber surface constructed by the present invention. It can be seen that the gradient of ion concentration in the bearing layer during implantation realizes the gradient of hardness, thereby realizing the natural transition of the mechanical hardness of the rubber soft substrate to the hard carbon film, and improving the high bearing characteristics of the rubber surface. Its high bearing capacity avoids the secondary brittle fracture during the film friction process (avoids furrow friction), thereby effectively reducing the film friction coefficient; the carbon film and the surface layer of the bearing layer achieve a perfect lattice match, thus ensuring the film's High bond strength.

2. Performance of high load-bearing and low-friction rubber surfaces

1. High bearing performance

Figure 2 is the SEM image of the wear scar of the carbon film on the surface of the original rubber without ion implantation (left) and the surface of the high load-bearing and low friction rubber constructed by the present invention (right). The surface morphology of the wear scar after friction is observed by SEM, and the carbon film on the rubber surface without ion implantation has serious mechanical brittle cracking during the friction process, while the structural surface film designed in the present invention does not have obvious brittleness under the condition of 30N heavy load Fragmentation, indicating its high load-bearing properties.

2. Bonding strength

The bonding strength of the film and the rubber was tested by the scratch method, and the results showed that the bonding strength reached 70~90N, indicating that the film has a high bonding strength.

3. Friction performance

The tribological properties of the rubber surface of the present invention were evaluated using a friction and wear tester. The friction conditions are: ball-disk rotation mode, normal load is 30N, friction pair is φ6mm GCr15 steel ball, and the test environment is the atmosphere. The results show that the friction coefficient of the conventional pure carbon film is higher (about 0.40), while the friction coefficient of the carbon-based composite coating of the present invention is significantly lower (0.11-0.15).

To sum up, the present invention has the following advantages compared with the prior art:

1. The present invention adopts the in-situ ion co-implantation technology, which effectively avoids the risk of interlayer peeling that exists in the bearing layer deposited on the rubber surface;

2. The carrier layer designed by the present invention has a gradient of ion concentration during implantation, that is, there is a gradient of hardness, which successfully realizes the natural transition of the mechanical hardness of the rubber soft substrate to the hard carbon film, thereby avoiding the film from breaking under ultra-high load. The risk of cracking and peeling is achieved, that is, its high load-bearing characteristics are achieved;

3. The carrier layer designed by the present invention stops the metal injection in the later stage of injection, and only injects carbon elements, so that it can achieve perfect lattice matching with the carbon film, thereby ensuring the high bonding strength of the film;

4. The process of the present invention is easy to control and has strong operability, and the obtained rubber surface has the characteristics of high load-bearing, high bonding and low friction, and is easy to realize large-scale industrial application.

Description of drawings

FIG. 1 is a schematic structural diagram of a high-load-bearing and low-friction rubber surface constructed by the present invention.

Figure 2 is the SEM image of the wear scar of the carbon film on the surface of the original rubber without ion implantation (left) and the surface of the high load-bearing and low friction rubber constructed by the present invention (right).

Detailed ways

The construction and performance of the high-load-bearing and low-friction rubber surface of the present invention will be further described below through specific examples.

Example 1

(1) Cut a 300×300×2mm black nitrile rubber sheet (surface finish Ra<200nm, thickness 3mm) into 30× ^30mm2 rubber sheets, soak them in a soapy water solution at 60°C for ultrasonic cleaning for 30min to remove the rubber surface Then take it out and soak it in distilled water at 90~95℃ for 30min ultrasonic cleaning to remove possible residual soapy water solution; finally dry it with dry nitrogen and place it in a drying oven at 120℃ for 20min to evaporate the rubber Moisture remains on the surface. The above process is repeated 5 times;

(2) After the rubber substrate was cooled to room temperature, it was placed in a magnetron sputtering vacuum chamber integrated with a Mevva-V.Ru vacuum arc ion source (a Ti target and a carbon target were pre-placed in the vacuum chamber as ion co-implantation). material), close the vacuum chamber door, and pump the vacuum to ≤1.0×10 ^–6 Pa; turn on the DC pulsed arc power supply, adjust the carbon target current to 45A, the duty cycle is 40%, and the beam current density is 0.48A/100cm ² ·s , the injection time is 480s. At the same time, the current of the metal target was gradually increased from 0A to 40A, the duty ratio was 50%, the beam density was gradually increased from 0A to 0.42A/100cm ² ·s, and the injection time was 360s; the accelerating voltage was controlled to -20kV, and the frequency was 1Hz;

(3) Turn off the arc power supply, immediately pass in argon and methane, turn on the graphite target sputtering power supply, adjust the target base distance to 10cm, the target current to 3A, the argon flow rate to 45sccm, and the flow ratio of Ar/CH ₄ to 1.5: 1. The substrate bias voltage is -700V, the air pressure is 1.0Pa, the duty cycle is 40%, the frequency is 60KHz, and the deposition time is 120min; after the deposition is completed, the temperature in the vacuum chamber is cooled to room temperature and the sample is taken out to obtain a high load bearing capacity. Low friction nitrile rubber surface. The surface of the nitrile rubber did not have obvious brittle cracking under the condition of 30N heavy load friction, and its friction coefficient was low (0.11).

Example 2

(1) The pre-cleaning steps of silicone rubber are the same as those in Example 1. Among them: the surface finish of the silicone rubber is Ra<200 nm, and the thickness is 3 mm; (2) After the rubber substrate is cooled to room temperature, it is placed in a magnetron sputtering vacuum chamber integrated with a Mevva-V.Ru vacuum arc ion source ( A Cr target and a carbon target are pre-positioned in the vacuum chamber as ion co-implantation materials). Close the vacuum chamber door, pump the vacuum to ≤1.0×10 ^–6 Pa; turn on the DC pulsed arc power supply, adjust the carbon target current to 60A, the duty cycle is 50%, the beam density is 0.64A/100cm ² ·s, the injection time for 480s. At the same time, the metal target current was gradually increased from 0A to 40A, the duty ratio was 50%, the beam density was gradually increased from 0A to 0.42A/100cm ² ·s, and the injection time was 360s; the accelerating voltage was controlled to -30kV, and the frequency was 3Hz;

(3) Same as Example 1. A high load bearing low friction silicone rubber surface is obtained. The surface of the silicone rubber does not have obvious brittle fracture under the condition of 30N heavy load friction, and its friction coefficient is low (0.12).

Example 3

(1) The fluororubber pre-cleaning steps are the same as those in Example 1. Among them: fluorine rubber surface finish Ra<200nm, thickness 5mm;

(2) After the rubber substrate was cooled to room temperature, it was placed in a magnetron sputtering vacuum chamber integrated with a Mevva-V.Ru vacuum arc ion source (W target and carbon target were pre-placed in the vacuum chamber as ion co-implantation). Material). Close the vacuum chamber door and pump the vacuum to ≤1.0×10 ^–6 Pa; turn on the DC pulsed arc power supply, adjust the carbon target current to 60A, the duty cycle is 50%, the beam density is 0.64A/100cm ² ·s, the injection time for 480s. At the same time, the current of the metal target was gradually increased from 0A to 40A, the duty ratio was 50%, the beam density was gradually increased from 0A to 0.42A/100cm ² ·s, and the injection time was 360s; the accelerating voltage was controlled to -30kV, and the frequency was 3Hz;

(3) Turn off the arc power supply, immediately pass in argon and methane, turn on the graphite target sputtering power supply, adjust the target-base distance to 12cm, the target current to 3A, the argon flow rate to be 60sccm, and the flow ratio of Ar/CH ₄ to 1.5: 1. The substrate bias voltage is -700V, the air pressure is 1.5Pa, the duty cycle is 45%, the frequency is 70KHz, and the deposition time is 150min; after the deposition is completed, the temperature in the vacuum chamber is cooled to room temperature and the sample is taken out, and the present invention can be obtained. high load bearing low friction fluoroelastomer surface. The fluororubber surface did not experience obvious brittle cracking under the condition of 30N heavy load friction, and its friction coefficient was low (0.15).

Claims (2)

1. A method for constructing a high-bearing low-friction rubber surface through in-situ ion co-injection comprises the steps of taking a metal target and a carbon target as ion co-injection materials, adopting a vacuum arc ion source, co-injecting metal and carbon elements as a bearing layer into the cleaned rubber surface in situ, and depositing a carbon film on the bearing layer by adopting magnetron sputtering, thereby obtaining the high-bearing high-combination low-friction rubber surface;

and (3) carrying layer implantation deposition: vacuum-pumping to 1 × 10^-6Pa; adjusting the current of the carbon target material to be 45-60A, the duty ratio to be 40-50% and the beam current density to be 0.48-0.64A/100 cm²S, injection time 480 s; meanwhile, the current of the metal target is adjusted to be gradually increased from 0A to 40A, the duty ratio is 50%, and the beam current density is gradually increased from 0A to 0.42A/100cm²S, injection time 360 s; controlling the accelerating voltage to be-20 to-30 kV and the frequency to be 1-3 Hz;

the metal target material is one of Ti, Cr and W targets;

the magnetron sputtering deposition of the carbon film: adopting a graphite target, wherein the target base distance is 8-12 cm, the target current is 3A, the argon flow is 45-60 sccm, and Ar/CH₄The flow ratio of (A) is 1.5:1, the substrate bias is-700V, the air pressure is 1-1.5 Pa, the duty ratio is 40-45%, the frequency is 60-70 KHz, and the deposition time is 120-150 min.

2. The method of constructing a high load bearing low friction rubber surface by in situ ion co-implantation as claimed in claim 1 wherein: the rubber substrate is one of nitrile rubber, fluororubber and silicon rubber, the surface roughness of the rubber is less than or equal to 200nm, and the thickness of the rubber is 3-5 mm.

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