CN112301317B

CN112301317B - Surface treatment process for claw type vacuum pump rotor

Info

Publication number: CN112301317B
Application number: CN202011185296.0A
Authority: CN
Inventors: 许瀚程; 张会霞; 许同柱; 邹昶方
Original assignee: Lianyungang Hengshun Industrial Technology Co ltd
Current assignee: Lianyungang Hengshun Industrial Technology Co ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-05-18
Anticipated expiration: 2040-10-30
Also published as: CN112301317A

Abstract

The invention discloses a surface treatment process for a claw type vacuum pump rotor, and relates to the technical field of surface treatment of vacuum pump rotors. The surface treatment process specifically comprises the following steps: pretreating, namely quenching and tempering the substrate, and then carrying out coarse grinding to fine grinding by using sand paper; ultrasonic impact nano treatment, namely performing nano treatment on the surface of the matrix by using a milligram energy ultrasonic treatment technology; preparing a coating by double-cathode plasma sputtering deposition, cleaning a furnace chamber, installing a workpiece, and fixing a target material and a substrate; vacuumizing the furnace cavity, cleaning the workpiece, and depositing a coating. The base material treated by the surface treatment process has excellent corrosion resistance and abrasion resistance, good fatigue performance and longer service life.

Description

Surface treatment process for claw type vacuum pump rotor

Technical Field

The invention belongs to the technical field of vacuum pump rotor surface treatment, and particularly relates to a claw type vacuum pump rotor surface treatment process.

Background

The vacuum industry is an important basic link in the technical field of national industry, is highly valued by scientific research institutions at home and abroad, and is widely applied to industries such as national defense and scientific engineering, steel industry, film coating, microelectronic information, semiconductors, biomedicine, chemical industry, food, environmental protection and the like. The comprehensive performance of the vacuum equipment is related to the production capacity and the research and development capacity of the whole high and new technical equipment of the country, in recent years, the reintegration of the national resource structure puts higher requirements on cleanness, no pollution and artificial intelligence, and the vacuum pump equipment develops towards the direction of high quality, high efficiency and high automation for the inevitable trend.

The claw vacuum pump is a preferred vacuum device in the fields of foreign microelectronic production, IT research and development, medicine, special precision machining and the like due to natural advantages. In a general vacuum system, due to technical problems of mechanical abrasion, backflow of polluted gas and the like caused by high-speed rotation of a rotor, the performance of a vacuum pump is seriously reduced after the vacuum pump runs for a long time, so that the requirements of corrosion resistance, stable pumping speed and environment friendliness and cleanness of pumped environment cannot be met.

Disclosure of Invention

The invention aims to provide a surface treatment process for a claw type vacuum pump rotor, which can effectively improve the wear resistance and corrosion resistance of the surface of the rotor, improve the fatigue performance of the rotor, and has longer service life and higher use efficiency.

The technical scheme adopted by the invention for realizing the purpose is as follows:

a preparation method of a target material for a claw type vacuum pump rotor surface treatment process comprises the following steps:

uniformly mixing Ta powder, Si powder, Cr powder and Bi powder, pouring absolute ethyl alcohol, ball-milling and drying; then, a deposition target material is obtained by adopting a cold isostatic pressing technology;

wherein, the mass ratio of the Ta powder, the Si powder, the Cr powder and the Bi powder is 2: 7: 0.7-0.8: 0.3 to 0.6. TaSi₂As a novel structural material with great potential, the material has good comprehensive performance, high melting point, good mechanical property, higher thermal stability and oxidation resistance, but the crystal of the material contains a large number of Si-Si covalent bonds, so that the material has higher room temperature brittleness. Alloying Cr and Bi to replace TaSi₂The silicon element in the material can improve the plastic deformation capacity of the material; the coating is coated on the surface of a substrate such as stainless steel to form a coating, so that the corrosion resistance and the abrasion resistance of the coating can be improved.

Preferably, the cold isostatic pressing technique operates specifically as: pressing under the pressure of 600-630 MPa, sintering in an argon atmosphere, and preserving heat for 3-4 h at 1000 ℃.

A surface treatment process for a claw type vacuum pump rotor comprises the following steps:

s1: pretreating, namely quenching and tempering the substrate, and then carrying out coarse grinding to fine grinding by using sand paper;

s2: ultrasonic impact nano treatment, namely performing nano treatment on the surface of the matrix by using a milligram energy ultrasonic treatment technology;

s3: preparing coating by double-cathode plasma sputtering deposition, cleaning furnace chamber and installing workpiece, and using the above-mentioned target materialFixing with the substrate; vacuumizing the furnace cavity, cleaning the workpiece, and depositing a coating. The surface hardness, the surface residual compressive stress and the wear resistance of the material can be improved by the ultrasonic impact nanocrystallization treatment of the surface of the substrate, but the mechanical treatment mode of the material can not avoid the generation of plastic accumulation with good impact traces in the remolding process of the surface of the substrate, so that the fatigue strength and the corrosion resistance of the material can not obtain better effects. Coating a layer of Cr and Bi alloyed TaSi on the surface of a matrix subjected to ultrasonic impact nano treatment₂The nanocrystalline coating effectively improves the dynamic process of the mutual combination of microscopic particles, improves the combination strength between the coating and a substrate, and reduces the risk of coating peeling; the corrosion resistance and the abrasion resistance of the base material are better improved by compounding the two materials, and the service life of the base is prolonged.

Preferably, the quenching and tempering process in the step S1 is oil cooling at a quenching temperature of 840-860 ℃ and air cooling at a tempering temperature of 560-570 ℃.

Preferably, the specific experimental parameters of the ultrasonic impact nano treatment in step S2 are set as follows: the step pitch is 0.15-0.16 mm, the feed is 3400-3500 mm/min, the working air pressure is 0.1-0.2 MPa, and the power supply voltage is 220-228V.

Preferably, the distance between the target and the substrate in step S3 is 8-10 mm.

Preferably, the experimental parameters for coating deposition in step S3 are set as follows: the air pressure is adjusted to 33-35 Pa, the workpiece electrode voltage is adjusted to-275 to-300V, and the source electrode voltage is adjusted to-700 to-750V; the temperature is 790-800 ℃, and the heat preservation is carried out for 3-4 h.

Preferably, the thickness of the deposited coating in step S3 is 10-15 μm.

Preferably, after the ultrasonic impact nanocrystallization treatment in step S2, a high-energy particle infiltration treatment is performed, wherein the infiltration elements are Ir and Nd, and the mass ratio of the two substances is 1: 0.73 to 0.93. By utilizing a high-energy particle injection alloying technology and injecting Ir and Nd elements into the base material, the damage of ultrasonic impact on the surface material of the base material can be reduced, the fatigue performance of the base material can be improved, and the binding force between the base material and the coating can be improved.

Compared with the prior art, the invention has the following beneficial effects:

using Cr and Bi alloysChemical TaSi₂The obtained material has excellent plastic deformation capability, and the corrosion resistance and the abrasion resistance of the material can be effectively improved. After the surface of the substrate is processed by ultrasonic impact nano treatment, a layer of Cr and Bi alloyed TaSi is coated₂The nanocrystalline coating can improve the bonding strength between the coating and the substrate and reduce the risk of coating peeling; the corrosion resistance and the abrasion resistance of the base material are better improved by compounding the two materials, and the service life of the base is prolonged. In addition, Ir and Nd elements are injected into the base material by utilizing a high-energy particle injection alloying technology, so that the fatigue property of the base material can be effectively improved, and the binding force between the base material and the coating is improved.

Therefore, the invention provides a surface treatment process for a claw type vacuum pump rotor, which can effectively improve the wear resistance and corrosion resistance of the surface of the rotor, improve the fatigue performance of the rotor, and has longer service life and higher use efficiency.

Drawings

FIG. 1 is a schematic diagram showing the results of XRD test in Experimental example 1 of the present invention;

FIG. 2 is a graph showing the comparison of the results of the hardness and elastic modulus tests in test example 1 of the present invention;

FIG. 3 is a comparative schematic view of the results of the plastic deformability test in test example 1 of the present invention;

FIG. 4 is a graph showing the comparison of the results of the binding force test in test example 1 of the present invention;

FIG. 5 is a graph showing a comparison of the results of the abrasion performance test in test example 1 of the present invention;

FIG. 6 is a graph showing the comparison of the results of the gas corrosion performance test in test example 2 of the present invention;

FIG. 7 is a comparison of the results of the fatigue property test in test example 3 of the present invention.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to the following detailed description and the accompanying drawings:

the Ta powder, the Si powder, the Cr powder and the Bi powder used in the embodiment of the invention are all produced by Beijing Lichenxin Chuang Limited company and have the specifications as follows: ta powder (more than or equal to 99.9 percent and minus 200mesh), Si powder (more than or equal to 99.9 percent and minus 200mesh), Cr powder (more than or equal to 99.9 percent and minus 200mesh) and Bi powder (more than or equal to 99.9 percent and minus 200 mesh).

The examples of the present invention used 40Cr steel as the experimental substrate, and the chemical compositions thereof are shown in table 1.

TABLE 140 chemical composition of Cr steel TABLE (w/%)

C

Si

Mn

Cr

S

P

Ni

Cu

0.37～0.15

0.17～0.37

0.5～0.8

0.8～1.1

≤0.03

≤0.25

≤0.03

Example 1:

preparing a target material:

mixing Ta powder, Si powder, Cr powder and Bi powder according to the mass ratio of 2: 7: 0.7: 0.3 of the total weight is put into a ball milling tank for uniform mixing, and absolute ethyl alcohol is poured into the ball milling tank; then ball milling is carried out for 10h by a planetary ball mill at the rotating speed of 300 r/min. Then pouring the mixture into a clean container and putting the container into an oven for drying. And then pressing the uniformly mixed powder into a target material by adopting a cold isostatic pressing technology under the pressure of 600MPa, sintering in an argon atmosphere, and preserving heat for 3 hours when the temperature in a furnace chamber rises to 1000 ℃ to obtain the deposition target material.

s1: pretreating, namely quenching and tempering the substrate; the substrate is

The quenching and tempering process of the circular plate sample comprises oil cooling at the quenching temperature of 850 ℃ and air cooling at the tempering temperature of 570 ℃; then, carrying out coarse grinding to fine grinding treatment by using sand paper;

s2: ultrasonic impact nano treatment, namely performing nano treatment on the surface of the matrix by using a milligram energy ultrasonic treatment technology; the specific experimental parameters are as follows: step pitch is 0.15mm, feed is 3500mm/min, working air pressure is 0.1MPa, power supply voltage is 228V, current is 1.17V, resonance voltage is 13.09V, and amplitude is 8 mu m;

s3: preparing a coating by double-cathode plasma sputtering deposition:

(1) cleaning the furnace chamber and installing the workpieces, firstly wiping the inner wall of the furnace chamber and each workpiece by using alcohol, then installing and fixing the workpieces, finally placing a target material and a substrate, and positioning and fixing the distance between the target material and the substrate by 10 mm;

(2) vacuumizing the furnace cavity, closing an exhaust valve, and starting a mechanical pump; when the pressure value in the furnace is reduced to below 10Pa, starting the molecular pump, simultaneously opening the cooling water circulation system, and after air extraction is carried out for 25min, enabling the interior of the furnace chamber to reach a limit vacuum state;

(3) cleaning a workpiece, opening an argon valve, introducing argon, and stabilizing the pressure in the furnace at 20Pa by controlling the valve; then, the voltage of the workpiece is adjusted to-300V, and the holding time is 10 min;

(4) depositing a coating, after cleaning a workpiece, adjusting the pressure in the furnace to 35Pa, slowly adjusting the voltage of the workpiece to-275-300V, and adjusting the voltage of a source electrode to-700-750V; after the furnace reaches a stable state, the thermometer stably displays 800 ℃, and the temperature is kept for 3 hours in a timing way; and then according to the experimental operation sequence, slowly adjusting the source electrode voltage and the workpiece electrode voltage to 0, simultaneously stopping the molecular pump and the mechanical pump, turning off the power supply, and taking out the sample after cooling for 2 hours by using circulating water. The coating thickness was 12 μm.

Example 2:

the preparation of the target material differs from example 1 in that: the mass ratio of Ta powder, Si powder, Cr powder and Bi powder is 2: 7: 0.8: 0.4.

the surface treatment process of a claw type vacuum pump rotor was the same as in example 1. Wherein the thickness of the coating layer was 10 μm.

Example 3:

the preparation of the target material differs from example 1 in that: the mass ratio of Ta powder, Si powder, Cr powder and Bi powder is 2: 7: 0.75: 0.5.

the surface treatment process of a claw type vacuum pump rotor was the same as in example 1. The coating thickness was 13 μm.

Example 4:

the preparation of a photocatalyst for a sewage sterilizer is different from that of example 1 in that:

the preparation of the target material differs from example 1 in that: the mass ratio of Ta powder, Si powder, Cr powder and Bi powder is 2: 7: 0.8: 0.6.

the surface treatment process of a claw type vacuum pump rotor was the same as in example 1. The coating thickness was 15 μm.

Example 5:

the target material was prepared as in example 1.

The difference between the surface treatment process of the claw type vacuum pump rotor and the embodiment 1 is that:

and S2, after ultrasonic impact nanocrystallization, performing high-energy particle infiltration treatment, wherein the infiltration elements are Ir and Nd, and the mass ratio of the Ir to the Nd is 1: 0.79.

the high-energy particle injection-infiltration treatment process comprises the following steps: introducing argon gas into a closed ion infiltration furnace, enabling facilities and a sample in the furnace to be in an argon gas atmosphere, ionizing the argon gas in the furnace into ions through abnormal glow discharge of a barrel-shaped cathode, impacting the well-placed Ir rod and Nd rod by argon ions moving at a high speed, generating corresponding ions, impacting the surface of the sample, and pumping the ions into the sample. The experimental parameters were set as: the voltage is 600V, the temperature is 490 ℃, the heat preservation time is 4h, and the air pressure is 130 Pa.

Comparative example 1:

the preparation of the target material differs from example 1 in that: only Ta powder and Si powder are contained, and the mass ratio of the Ta powder to the Si powder is 2: 8.

the surface treatment process of a claw type vacuum pump rotor was the same as in example 1.

Comparative example 2:

the preparation of the target material differs from example 1 in that: only comprising Ta powder, Si powder and Cr powder, wherein the mass ratio of the Ta powder to the Si powder to the Cr powder is 2: 7.3: 0.7.

Comparative example 3:

the preparation of the target material differs from example 1 in that: only Ta powder, Si powder and Bi powder are contained, and the mass ratio of the Ta powder to the Si powder is 2: 7.3: 0.3.

Test example 1:

characterization and performance testing of as-deposited coatings

1. X-ray diffraction (XRD)

The X-ray diffractometer (D8 Advance, Bruker, Germany) gave a voltage and a current of 40kV and 40mA, respectively, using Cu Ka: (K)

) The radiation source adopts step-type scanning with a scanning speed of 0.1 DEG s^-1And the step length is 0.02 degrees, and data with the 2 theta of 20-80 degrees are recorded. The XRD pattern was processed using Jade6 software to analyze its phase composition, crystal structure, etc.

Comparative example 1Example 1 the coating after surface treatment was subjected to the above test and the results are shown in fig. 1, wherein the black arrows are according to TaSi₂The standard JCPDS data (file No.38-0483) of (1). From the analysis in the figure, compared with comparative example 1, no other characteristic peak of tantalum silicide appears after the introduction of Cr and Bi, which shows TaSi after the alloying of Cr and Bi₂The coating does not undergo a phase transition, but the corresponding diffraction peaks are all shifted towards low angles, since the atomic radius of Cr and Bi is larger than that of Si. In addition, the XRD patterns of both the example 1 and comparative example 1 groups showed relatively weak and broad diffraction peaks, which were caused by the ultra-fine grain sizes of the two deposited layers.

2. Nanoimprint and indentation testing

In order to accurately evaluate the mechanical properties of the deposited coating and the matrix material, the hardness and elastic modulus of the coating are characterized by using a nanoindentation test technique. At the beginning of the experiment, the height of the sample is adjusted to make the pressure head close to the surface of the sample, the contact zero point of the material is recorded, and then the indentation test is carried out at a constant loading rate of 40mN/min and with a maximum load of 20 mN. After loading to maximum load, maintain 10 s. In order to eliminate the interference of the creep factors on the experimental results, when the load is unloaded to 90%, the load is maintained for 100s, and finally the load is unloaded. And randomly selecting 5 test points for each sample to test, and averaging the results. When the coating is subjected to an external load, the total deformation energy generated by the indenter can be divided into two parts: plastic deformation dissipation energy and elastic recovery energy. The total deformation energy can be represented by the area enclosed by the loading curve and the maximum penetration depth, while the elastic recovery energy can be represented by the area under the unloading curve; w_p/W_tThe ratio of (d) represents the contribution of elasticity and plasticity to the total deformation. The experiments also evaluated the material hardness levels and fracture toughness exhibited at different loads using a micro vickers hardness tester (model 401 MVA). The testing method comprises applying 1000g load to the sample with diamond pyramid pressure head, measuring the diagonal length and indentation depth of the indentation left on the sample, and determining the hardness of the object.

The results of the above tests on the coatings of comparative example 1 and example 1 are shown in fig. 2 and 3. Is divided intoIt can be seen that the hardness values of the coatings obtained in comparative example 1 and example 1 are 7.7 times and 7.1 times higher than those of the base material, and the elastic modulus is 2.4 times and 2.2 times higher than that of the base material. Wherein the coating of comparative example 1 has a slightly higher corresponding value than that of example 1, indicating that the addition of Cr and Bi reduces the hardness and elastic modulus of the coating; in addition, as can be seen from FIG. 3, example 1 coating W_p/W_tThe ratio of (a) to (b) is greater than that of comparative example 1, indicating that the addition of Cr and Bi improves the plastic deformability of the coating.

3. Scratch test

Scratch testing is widely used to characterize the bonding ability between a coating and a substrate. The model of a scratch tester adopted in the test is WS-2004, the scratch test is carried out on the surface of a sample with the size of 10mm multiplied by 3mm, the sliding speed of the transverse movement of a pressure head is 1mm/min, the load application range is 0-100N, the loading rate is 40mN/min, and the total length of scratches is 5 nm. In the process of the transverse sliding of the pressure head, with the increasing of the applied load, the surface of the coating layer can be peeled off or cracked, and at the moment, the critical load value corresponding to the damage of the coating layer is the bonding strength between the coating layer and the substrate.

The results of the above tests on the coatings obtained in comparative examples 1 to 3 and examples 1 to 5 are shown in FIG. 4. Analysis can show that the coating obtained in example 1 begins to peel or crack when the load is 68N, which is obviously higher than that of comparative examples 1-3 and slightly better than that of examples 2-4, and the addition of Cr and Bi promotes the binding force between the coating and the substrate; and the effect of the embodiment 5 is better than that of the embodiment 1, which shows that the Ir and the Nd are injected into the substrate after the high-energy particle injection treatment, so that the effect of enhancing the bonding force between the coating and the substrate is achieved.

4. Frictional wear performance test

The friction and wear test adopts a WTM-2E miniature friction and wear tester which comprises a high-sensitivity loading and friction force measuring system, a sample rotating platform, an electrode transmission system, a precise X-direction displacement platform, a precise lifting support and the like. The test load is 500g, the rotating speed is 334.9mm/s, the material of the counter grinding ball is GCr15 alloy ball, and the diameter of the counter magic ball is

Before the friction and wear test, the sample is washed clean by alcohol in advance, dried and weighed on an electronic balance, and the average value is obtained continuously for three times. After the friction and wear test is finished, the tested sample is placed in alcohol and cleaned for 5min by an ultrasonic cleaner, the sample is taken out, the sample is dried by a blower and weighed for three times, an average value is obtained, and the wear weight loss of the sample can be obtained through the weight difference before and after the test. The friction data can be read directly on the computer.

The results of the above tests on the samples surface-treated in comparative examples 1 to 3, example 1 and example 3 are shown in FIG. 5. As is clear from the analysis of the graph, the wear loss increases with time from the tendency of the state of the wear loss. Wherein, after the surface treatment of the example 1, the abrasion weight loss is obviously less than that of the comparative examples 1-3, which shows that the Cr and Bi alloyed TaSi₂The friction and wear resistance of the coating is improved, and the coating can play a good protection role when being coated on the surface of the base material. The effect of example 1 is better than that of example 3.

Test example 2:

gas corrosion testing

The test of the whole device mainly comprises two systems: a sample mixed gas box system and a speed regulation and control system. The test experiment was exposed to an area of 10mm by 10mm, and the sample was held at a position 30mm from the center of the axis of rotation. The rotation speed is controlled by a speed-regulating alternating current motor, the power of the motor is 2.2KW, and the rotation speed range is 0-4000 rpm. Wherein, the mixed gas includes: SO (SO)₂、NO₂、Cl₂、H₂S, the concentration is 1%; the test temperature is 25 +/-2 ℃ and the humidity is 93 +/-2%. The gas corrosion resistance is represented by the weight loss of the material. Experiment the total weight loss W of the material after being flushed for 48h with mixed gas is tested at the speed of 436m/s_TThen, the pure scouring weight loss W after 48h of argon scouring at the same speed is tested_EFinally, the weight loss W in the mixed gas under the static condition is tested_CAnd the amount of weight loss W is interacted_SCalculated according to the following formula:

W_S(％)＝W_T-W_E-W_C

the results of the above tests on the base material, the samples obtained in comparative examples 1 to 3 and examples 1 to 5 are shown in FIG. 6. Analysis in the figure shows that the interaction weight loss of the sample prepared in the example 1 is 28.1%, which is obviously lower than that of the comparative examples 1-3 and slightly lower than that of the examples 2-4, and the addition of Cr and Bi obviously improves the corrosion resistance of the coating, thereby enhancing the corrosion resistance of the surface of the substrate.

Test example 3:

normal temperature high cycle fatigue test

And carrying out a normal-temperature high-cycle fatigue test on the sample according to the relevant regulation of the national standard GB/T3075-2008. A GPS 200 type high-frequency fatigue testing machine produced by Zhongji test Equipment GmbH is adopted. The fatigue test method used belongs to a tensile-tensile fatigue test in a high cycle fatigue test, and is in a sine wave form, and the stress ratio adopted is that R is 0.1, namely the ratio of the minimum stress value to the maximum stress value. The fatigue performance is represented by the maximum stress value which can be borne by the sample obtained by the fatigue S-N curve.

The results of the above tests on the substrates treated in step S2 in examples 1 and 5 are shown in fig. 7. From the analysis of the figure, the number of cycles was 1X 10⁴In time, the maximum stress value which can be borne by the material of the embodiment 5 is 413MPa and is larger than 368MPa of the embodiment 1, and the maximum stress value is improved by 12.3 percent; at a cycle number of 1X 10⁶In time, the maximum stress value which can be borne by the material of the embodiment 5 is 349MPa which is larger than 273MPa of the material of the embodiment 1, and the maximum stress value is improved by 27.8 percent; the fatigue performance of the matrix material is improved after the high-energy particle injection and infiltration technology treatment.

Conventional techniques in the above embodiments are known to those skilled in the art, and therefore, will not be described in detail herein.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A preparation method of a target material for a claw type vacuum pump rotor surface treatment process comprises the following steps:

wherein the mass ratio of the Ta powder, the Si powder, the Cr powder and the Bi powder is 2: 7: 0.7-0.8: 0.3 to 0.6.

2. The method for preparing the target material for the surface treatment process of the claw vacuum pump rotor according to claim 1, wherein the method comprises the following steps: the cold isostatic pressing technology is specifically operated as follows: pressing under the pressure of 600-630 MPa, sintering in an argon atmosphere, and preserving heat for 3-4 h at 1000 ℃.

3. A surface treatment process for a claw type vacuum pump rotor comprises the following steps:

s3: preparing a coating by double-cathode plasma sputtering deposition, cleaning a furnace chamber and installing a workpiece, and fixing the target material of claim 1 with a substrate; vacuumizing the furnace cavity, cleaning the workpiece, and depositing a coating.

4. A surface treatment process for a claw vacuum pump rotor according to claim 3, characterized in that: the quenching and tempering process in the step S1 is oil cooling at a quenching temperature of 840-860 ℃ and air cooling at a tempering temperature of 560-570 ℃.

5. A surface treatment process for a claw vacuum pump rotor according to claim 3, characterized in that: setting specific experimental parameters of ultrasonic impact nano treatment in the step S2: the step pitch is 0.15-0.16 mm, the feed is 3400-3500 mm/min, the working air pressure is 0.1-0.2 MPa, and the power supply voltage is 220-228V.

6. A surface treatment process for a claw vacuum pump rotor according to claim 3, characterized in that: and in the step S3, the distance between the target and the substrate is positioned by 8-10 mm.

7. A surface treatment process for a claw vacuum pump rotor according to claim 3, characterized in that: setting the experimental parameters of the coating deposition in the step S3: the air pressure is adjusted to 33-35 Pa, the workpiece electrode voltage is adjusted to-275 to-300V, and the source electrode voltage is adjusted to-700 to-750V; the temperature is 790-800 ℃, and the heat preservation is carried out for 3-4 h.

8. A surface treatment process for a claw vacuum pump rotor according to claim 3, characterized in that: the thickness of the deposited coating in the step S3 is 10-15 μm.