CN108149220B - A kind of rare earth yttrium doped molybdenum disulfide self-lubricating composite coating and preparation method thereof - Google Patents

Abstract

The present invention provides a kind of rare earth Yt doped molybdenum disulfide self-lubricating composite coatings and preparation method thereof.Specifically, rare earth doped yttrium in molybdenum disulfide self-lubricating composite coating of the invention, wherein the yttrium molar content in the composite coating is 0.1%~5%, by the total moles meter of the composite coating.The present invention uses sublimed sulfur (S), six chloride hydrate yttrium (YCl₃·6H₂) and molybdenum trioxide (MoO O₃) powder be raw material, rare earth Yt doped molybdenum disulfide self-lubricating composite coating is prepared using chemical vapor deposition process.Molybdenum disulfide self-lubricating coat in use of the invention has good wearability and self-lubrication and excellent around plating property, can implement coating deposition on the large scale complex part of shape.

Description

A kind of rare earth yttrium doped molybdenum disulfide self-lubricating composite coating and preparation method thereof

technical field

The invention relates to the field of solid lubricating materials, in particular to a rare earth yttrium-doped molybdenum disulfide self-lubricating coating and a preparation method thereof. The molybdenum disulfide self-lubricating coating can be used to reduce friction and wear in micromechanical electronic systems and aerospace industries, and improve their performance and service life.

Background technique

As an excellent solid lubricant material, molybdenum disulfide (MoS ₂ ) has high application value in the field of supersolid lubrication, especially in reducing friction and wear in micromechanical electronic systems and aerospace industry, improving its performance and In terms of life, the super solid lubrication technology based on MoS ₂ has a strong application space.

Due to its graphite-like laminated structure, MoS2 has been widely used as a self _- lubricating solid lubricant under high temperature and vacuum environments. Correspondingly, MoS2 self _- lubricating coatings have also received more and more attention. Although MoS2 self _- lubricating coatings can be prepared by many methods, such as physical vapor deposition (PVD), sulfide electroplating of Mo, heating of chemical solutions containing liquid Mo and S precursors, chemical vapor deposition (CVD), and metal-organic CVD (MOCVD). However, among these preparation processes, PVD is the most used. Among the PVD MoS ₂ coatings, transition metal-doped MoS ₂ coatings, such as MoS ₂ coatings doped with Ti, Ni, Au, etc., have been studied more at present, but rare earth elements, especially those with excellent properties The element yttrium-doped MoS ₂ coating has not been reported so far. At the same time, compared with PVD, CVD has some unique advantages. For example, the coating structure of CVD can make the coating structure uniform, and it can grow with the shape on large-scale and complex workpieces with inner holes; secondly, it can be deposited by CVD _The process makes MoS uniformly diffused and dispersed into the hard CVD carbide and nitride film, this type of self-lubricating composite coating has excellent wear resistance at high temperature. In addition, CVD has been widely used in the preparation of ceramic composite thin films.

However, MoS2 self _- lubricating coatings are rarely prepared using CVD processes. In this small amount of CVD-MoS ₂ self-lubricating coating research, some researchers used Mo halides such as MoF ₆ , MoCl ₅ , etc. and H ₂ S as precursors, which caused the equipment to be easily corroded; Molybdenum (Mo(CO) ₆ ), Mo-containing organic matter (Mo(St-Bu) ₄ ), etc., and H ₂ S are used as precursors, and the coating quality is very poor.

Therefore, the field needs to develop a new yttrium-doped high-performance CVD-MoS ₂ self-lubricating composite coating that is less corrosive to equipment and has high coating quality.

Contents of the invention

The purpose of the present invention is to obtain a molybdenum disulfide self-lubricating composite coating with uniform and compact structure and excellent friction and wear performance through rare earth yttrium doping.

The first aspect of the present invention provides a molybdenum disulfide self-lubricating composite coating, the composite coating is doped with rare earth element yttrium, wherein the molar content of the yttrium element in the composite coating is 0.1% to 5% %, by the total molar weight of the composite coating.

In another preferred example, the thickness of the composite coating is 1-3 μm.

In another preferred example, the coefficient of friction of the composite coating is 0.05-0.30.

In another preference, the components used to prepare the composite coating include:

Component (a): sulfur powder, sulfur-containing gas source, or a combination thereof;

Component (b): molybdenum oxides, molybdenum salts, molybdenum-containing metallo-organics, or combinations thereof; and

Component (c): yttrium salt, yttrium oxide, or combinations thereof.

In another preferred example, the component (a) is sulfur powder.

In another preferred example, the purity of the sulfur powder is 99.95%-99.99%.

In another preferred example, the molybdenum oxide is MoO ₃ .

In another preferred example, the average particle size of the molybdenum trioxide (MoO ₃ ) is ≤10 μm.

In another preferred example, the purity of the MoO ₃ is 99.5%-99.99%.

In another preferred embodiment, the molybdenum salt is selected from the group consisting of MoF ₆ , MoCl ₅ , Mo(CO) ₆ , or combinations thereof.

In another preferred example, the molybdenum-containing metal organic compound is Mo(St-Bu) ₄ .

In another preferred example, the component (c) is yttrium chloride hexahydrate (YCl ₃ ·6H ₂ O).

In another preferred example, the purity of the YCl ₃ ·6H ₂ O is 99.95%-99.99%.

In another preference, the composite coating is prepared by chemical vapor deposition method comprising the following steps:

(i) providing component (a) as a source of sulfur, component (b) as a source of molybdenum, component (c) as a source of yttrium, and a supporting matrix;

(ii) under reducing gas and inert gas atmosphere, heating described component (a), (b) and (c), described component (a), (b) and (c) are carried in described support A chemical deposition reaction occurs on the substrate, thereby forming the composite coating as described in the first aspect of the present invention on the carrier substrate.

A second aspect of the present invention provides a method for preparing a composite coating as described in the first aspect of the present invention, the method comprising steps as follows:

(i) providing component (a) as a source of sulfur, component (b) as a source of molybdenum, component (c) as a source of yttrium, and a supporting matrix;

(ii) under reducing gas and inert gas atmosphere, heating described component (a), (b) and (c), described component (a), (b) and (c) are carried in described support A chemical deposition reaction occurs on the substrate, thereby forming the composite coating as described in the first aspect of the present invention on the carrier substrate.

In another preferred example, the step (ii) also includes the following steps:

(ii-1) the molybdenum (VI) in the component (b) is reduced to molybdenum (IV) under the action of reducing gas;

(ii-2) the molybdenum (IV) is deposited on the carrier substrate and reacts with the gaseous sulfur source to form MoS ₂ on the carrier substrate; and the component (c) occurs Thermal decomposition reaction to generate elemental yttrium, which is evenly doped into the MoS ₂ ;

(ii-3) Lowering the temperature to form the composite coating as described in the first aspect of the present invention.

In another preferred example, the components (b) and (c) are placed on one end of the ceramic boat, the carrier substrate is placed on the other end of the ceramic boat, and the ceramic boat is placed in a tubular Furnace high temperature zone (first heating zone); and described component (a) is placed in another ceramic boat, and described another ceramic boat is placed in the low temperature zone that the heating band of tube furnace is wound (the first Two heating zones).

In another preferred embodiment, between steps (i) and (ii), it also includes: sealing and vacuuming the tube furnace, and then introducing protective gas.

In another preferred example, after the temperature in step (ii) reaches 200°C, the total pressure is always maintained at 200-400Pa, preferably 340-360Pa, most preferably 350Pa.

In another preferred example, after the temperature in step (ii) reaches 200° C., reducing gas and protective gas are always introduced.

In another preferred embodiment, the reducing gas includes hydrogen (H ₂ ), hydrogen sulfide (H ₂ S), or a combination thereof; preferably, it is hydrogen (H ₂ ).

In another preferred embodiment, the protective gas includes nitrogen (N ₂ ), argon (Ar), or a combination thereof; preferably, argon (Ar).

In another preferred embodiment, the volume ratio of H ₂ to Ar is 1:5˜1:50.

In another preferred example, the volume ratio of H ₂ to Ar is 1:10.

In another preferred embodiment, the reaction temperature in step (ii-2) is 200-1200°C; and/or the reaction time is 0.5-5 hours.

In another preferred example, the bearing substrate is selected from the group consisting of glass, ceramics, stainless steel, silicon wafers, cemented carbide, or combinations thereof.

In another preferred example, the substrate is 304 stainless steel with titanium nitride coating.

The third aspect of the present invention provides a workpiece on which the composite coating as described in the first aspect of the present invention is deposited.

In another preferred example, the workpiece includes a workpiece with a large size and complex shape.

In another preferred example, the workpiece includes pistons, bolts, bearings, and cutters.

The fourth aspect of the present invention provides a use of the composite coating described in the first aspect of the present invention, and the composite coating is used for resistant Grinding anti-corrosion.

It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described in the following (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, we will not repeat them here.

Description of drawings

Fig. ₁ is the XRD diffraction pattern of MoS composite coating;

Fig. ₂ is the SEM image of the surface morphology of the MoS2 composite coating;

Fig. 3 is the SPM figure of MoS ₂ composite coating surface micro-morphology;

Fig. 4 is the Raman spectrogram of MoS ₂ composite coating surface;

Figure 5 is the friction and wear curve of MoS ₂ coating; a: the friction and wear curve of pure MoS ₂ coating, the inset in the figure is the enlarged view of curve a; b: the friction and wear curve of Y/MoS ₂ composite coating.

Figure 6 is the microscopic topography of wear scars of MoS ₂ composite coating; among them, (a) 2D topography of wear scars, (b) 3D topography of wear scars.

Detailed ways

After extensive and in-depth research, the inventor unexpectedly developed a rare earth yttrium-doped molybdenum disulfide self-lubricating composite coating and its preparation method for the first time. The molybdenum disulfide self-lubricating composite coating of the present invention adopts a chemical vapor deposition process. By introducing the rare earth element yttrium, the structure of the MoS ₂ composite coating is changed, the coating structure is uniform and dense, and the CVD-MoS ₂ coating is effectively improved. The quality of the layer, while reducing the corrosiveness of the reaction by-products to the equipment. On this basis, the present invention has been accomplished.

the term

As used herein, the terms "self _- lubricating coating", "MoS2 composite coating", "molybdenum disulfide self-lubricating composite coating" and "composite coating" are used interchangeably and refer to the rare earth yttrium-doped Molybdenum self-lubricating composite coating.

As used herein, the term "pure MoS2 coating" refers to a molybdenum disulfide coating that is not _doped with the rare earth yttrium.

As used herein, the term "self-lubricating" refers to reducing the friction between friction surfaces or other forms of surface damage by compounding a solid lubricant with a low coefficient of friction into the bearing matrix.

As used herein, the term "Chemical Vapor Deposition (CVD)" refers to chemical reaction, using various energy sources such as heating, plasma excitation or light radiation, to make gaseous or vaporous chemical substances in the gas phase or gaseous phase in the reactor. A technique in which deposits are formed by chemical reactions on a solid interface. The common chemical reaction types are: thermal decomposition reaction, chemical synthesis reaction, redox reaction, chemical transport reaction, plasma enhanced reaction, etc.

As used herein, the term "coefficient of friction" refers to the ratio of the frictional force between two surfaces to the normal force acting on one of the surfaces, and is related to the roughness of the surface. The coefficient of friction was obtained by friction and wear tests.

The friction and wear test of the present invention is completed on the American Rtec-MFT multifunctional friction and wear testing machine. The friction motion mode adopts the linear reciprocating circular friction motion mode, and the GCr15 steel ball with Ф6mm and hardness of 61HRC is used as the pair, the linear displacement D is 5mm, the friction motion speed ν is 20mm/s, the running time t is 60min, and the load L is 5N. The friction and wear tests are all completed in the open atmosphere and at room temperature, the ambient temperature is 22-24°C, and the relative humidity RH=75%-80%. The friction and wear test under each load should be repeated at least 5 times, and new counter-friction steel balls should be replaced for each repeated test to ensure the repeatability of the test.

Molybdenum disulfide self-lubricating coating doped with rare earth yttrium

The invention provides a molybdenum disulfide self-lubricating coating doped with rare earth yttrium, and the composite coating is doped with rare earth element yttrium, wherein the molar content of yttrium element in the composite coating is 0.1%-5 %, by the total molar weight of the composite coating. The components used to prepare the composite coating include a source of sulfur, a source of molybdenum, and a source of yttrium. Described sulfur source includes (but is not limited to): sulfur powder, sulfur-containing gas source, or its combination; Described molybdenum source includes (but is not limited to): molybdenum oxide, molybdenum salt, molybdenum-containing metal organic compound, Or a combination thereof; the yttrium source includes (but not limited to): yttrium salt, yttrium oxide, or a combination thereof. The average value of the friction coefficient of the composite coating of the present invention is 0.12, and the thickness is 1-3 μm, wherein the friction coefficient is obtained by the above-mentioned friction and wear test method.

Preparation

The invention provides a method for preparing a high-performance CVD-MoS2 self _- lubricating composite coating that is weak to equipment corrosion. The steps of the method are as follows:

(1) In order to prevent by-product corrosion equipment, improve the quality of coating simultaneously, the present invention adopts molybdenum trioxide (MoO ₃ ) powder and sulfur (S) powder as precursor;

(2) Ar and _H2 are used as carrier gas and shielding gas;

(3) The rare earth element yttrium was introduced into the coating through yttrium chloride hexahydrate (YCl ₃ ·6H ₂ O), which greatly improved the microstructure of the MoS ₂ coating.

At the same time, the molybdenum trioxide powder in the present invention is analytically pure, with an average particle size of ≤10 μm and a purity of 99.5%.

The sulfur powder is analytically pure sublimated sulfur with a purity of 99.95%.

The yttrium chloride hexahydrate (YCl ₃ ·6H ₂ O) is analytically pure with a purity of 99.99%.

The flow rates of Ar and H ₂ used as the delivery carrier gas and shielding gas are 100 sccm and 10 sccm respectively, and the total gas pressure is 350 Pa.

A preferred CVD process is as follows: molybdenum trioxide, yttrium trichloride and sulfur powder are used as raw materials. First, weigh a certain amount of molybdenum trioxide and yttrium chloride hexahydrate powder and place them on one end of the ceramic boat, and place the 304 stainless steel substrate with titanium nitride (TiN) coating on the other end of the ceramic boat, and place the ceramic boat on the tube. The high-temperature zone of the type furnace; Weigh a relatively large amount of sulfur powder into another ceramic boat, and place it in the low-temperature zone where the heating belt is wound. Then the tube furnace was sealed and evacuated, and then high-purity argon gas was introduced. After doing this twice, the tube furnace starts to heat up. Heating the molybdenum source substrate area to 200°C in 10 minutes, flushing high-purity argon gas to maintain the pressure for 10 minutes, vacuuming for 30 minutes, and raising the temperature to 30°C from the reaction temperature at a rate of 20°C/min. At this point, the heating belt starts to heat the sulfur powder. The tube furnace continued to heat up to a certain reaction temperature at a rate of 5°C/min, and then kept at this temperature for a certain period of time, and finally let the tube furnace cool down slowly to 500°C, and then cooled to room temperature with the furnace. After 200° C., argon and hydrogen were fed throughout the process at a constant flow rate, and the pressure in the tube furnace was 350 Pa.

The preparation method of the present invention successfully solves the shortcomings of the previous CVD process, and finally prepares a yttrium-doped MoS ₂ self-lubricating composite coating (Y-MoS ₂ ) with a uniform and dense structure and excellent wear resistance. The prepared composite coating has an initial friction coefficient of about 0.07 under a load of 5N, and the friction coefficient is still not higher than 0.2 after a friction and wear test for 1 hour (3600s).

application

The molybdenum disulfide self-lubricating coating doped with rare earth yttrium of the present invention can be widely used in the field of wear resistance and anticorrosion, especially the wear resistance and anticorrosion of the workpiece surface with complex shape and large size, and the workpiece with complex shape and large size includes (but not limited to): micromechanical electronic devices, motor vehicles, aerospace equipment, nuclear reactors, generators, and other industrial equipment.

Main advantages of the present invention

The beneficial effects of the present invention are: the method uses molybdenum trioxide and sulfur powder as raw materials, and the produced by _- product SO is less corrosive to equipment than HF and HCl, and it is very convenient to recycle, and the deposited _MoS coating has high purity of impurity elements Less content.

1. The present invention introduces the rare earth element yttrium by innovatively adding yttrium chloride hexahydrate (YCl ₃ 6H ₂ O). The introduction of the rare earth element yttrium effectively changes the structure of the MoS ₂ composite coating, making the coating uniform Dense.

2. The chemical vapor deposition process can be used to prepare coatings on large-scale and complex workpieces, successfully solving the shortcomings of the previous CVD process, and finally preparing yttrium-doped MoS ₂ self-lubricating materials with uniform and dense structure and excellent wear resistance Composite coating (Y-MoS ₂ ). The prepared composite coating has an initial friction coefficient of about 0.07 under a load of 5N, and the friction coefficient is still not higher than 0.2 after a friction and wear test for 1 hour (3600s).

3. The present invention uses molybdenum trioxide and sulfur powder as raw materials, and the produced SO is less corrosive to equipment _than HF and HCl, and it is easy to recycle. _The deposited MoS coating has high purity and low impurity element content.

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. For the experimental methods without specific conditions indicated in the following examples, the conventional conditions or the conditions suggested by the manufacturer are usually followed. Percentages and parts are by weight unless otherwise indicated.

Example 1

First weigh 30 mg of MoO ₃ powder with a purity of 99.5% and 10 mg of YCl ₃ 6H ₂ O powder with a purity of 99.99% and place them on one end of the ceramic boat, and place a 304 stainless steel substrate with a titanium nitride (TiN) coating on the other side of the ceramic boat. At one end, the distance between the two is 7cm. This ceramic boat is placed in the high temperature zone of the tube furnace; 1.2g of sulfur powder with a purity of 99.95% is weighed and put into another ceramic boat, which is placed in the low temperature zone where the heating belt is wound. Then the tube furnace was sealed and evacuated, and then high-purity argon gas was introduced. After doing this twice, the tube furnace starts to heat up. Heating the molybdenum source substrate area to 200°C in 10 minutes, flushing with high-purity argon gas to keep the pressure for 10 minutes, vacuuming for 30 minutes, then raising the temperature to 770°C at a rate of 20°C/min. At this point, the heating belt starts to heat the sulfur powder to 130°C until it melts. The tube furnace continued to heat up to 800°C at a rate of 5°C/min, and kept at 800°C for 2 hours. After the reaction, let the tube furnace cool down slowly at 3°C/min to 500°C, and then cool down to room temperature with the furnace. After keeping warm at 200°C, 100 sccm argon and 10 sccm hydrogen were fed in the whole process, the flow rate was constant, and the pressure in the tube furnace was 350 Pa.

Figure 1 is the XRD diffraction pattern of the MoS ₂ composite coating; Figure 2 is the SEM image of the surface morphology of the MoS ₂ composite coating; Figure 3 is the SPM image of the surface microscopic morphology of the MoS ₂ composite coating; Figure 4 is the MoS ₂ composite The Raman spectrogram of the coating surface; the curve b in Fig. 5 is the friction and wear curve of the MoS2 composite coating _; Fig. ₆ is the microscopic topography of the wear scar of the MoS2 composite coating; where, (a) the wear scar 2D topography, (b) 3D topography of wear scars.

Example 2

First weigh 60mg _of 99.5% pure MoO3 powder and put it on one end of the ceramic boat. The 304 stainless steel substrate with titanium nitride (TiN) coating is placed on the other end of the ceramic boat. The distance between the two is 7cm. The ceramic boat is placed on the tube. The high-temperature zone of the type furnace; Weigh 3g of sulfur powder with a purity of 99.95% and put it into another ceramic boat, and place it in the low-temperature zone where the heating belt is wound. Then the tube furnace was sealed and evacuated, and then high-purity argon gas was introduced. After doing this twice, the tube furnace starts to heat up. Heating the molybdenum source substrate area to 200°C in 10 minutes, flushing with high-purity argon gas to keep the pressure for 10 minutes, vacuuming for 30 minutes, then raising the temperature to 770°C at a rate of 20°C/min. At this point, the heating belt starts to heat the sulfur powder to 130°C until it melts. The tube furnace continued to heat up to 800°C at a rate of 5°C/min and held at 800°C for 4 hours. After the reaction, let the tube furnace cool down slowly at 3°C/min to 500°C, and then cool down to room temperature with the furnace. After keeping warm at 200°C, 100 sccm argon and 10 sccm hydrogen were fed in the whole process, the flow rate was constant, and the pressure in the tube furnace was 350 Pa. The friction and wear curves of pure MoS2 coatings are shown in curve a in Fig. ₅ (the inset in Fig. 5 is an enlarged view of curve a, representing the friction and wear curves of undoped pure MoS2 coatings ₎ .

All documents mentioned in this application are incorporated by reference in this application as if each were individually incorporated by reference. In addition, it should be understood that after reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (7)

1. a kind of molybdenum disulfide self-lubricating composite coating, which is characterized in that the rare earth doped yttrium of the composite coating, In, the yttrium molar content in the composite coating is 0.1%~5%, by the total moles meter of the composite coating；

The composite coating with a thickness of 1~3 μm；

The coefficient of friction of the composite coating is 0.05~0.30.

2. composite coating as described in claim 1, which is characterized in that the component for being used to prepare the composite coating includes:

Component (a): sulphur powder, sulphur-containing gas source, or combinations thereof；

Component (b): molybdenum oxide, molybdenum salt, organic matter containing molybdenum, or combinations thereof；With

Component (c): yttrium salt, yttrium oxide, or combinations thereof.

3. composite coating as described in claim 1, which is characterized in that the composite coating is using including the following steps Chemical vapour deposition technique preparation:

(i) component (a), which is provided, as sulphur source, component (b) is used as yttrium source and bearing substrate as molybdenum source, component (c)；

(ii) under reducibility gas and inert gas atmosphere, the component (a), (b) and (c), the component (a), (b) are heated (c) chemical deposition reaction occurs on the bearing substrate, to form such as claim 1 on the bearing substrate The composite coating.

4. a kind of preparation method of composite coating as described in claim 1, which is characterized in that comprise the following steps that

(i) component (a), which is provided, as sulphur source, component (b) is used as yttrium source and bearing substrate as molybdenum source, component (c)；

(ii) under reducibility gas and inert gas atmosphere, the component (a), (b) and (c), the component (a), (b) are heated (c) chemical deposition reaction occurs on the bearing substrate, to form such as claim 1 on the bearing substrate The composite coating；

The component (a) is selected from the group: sulphur powder, sulphur-containing gas source, or combinations thereof；

The component (b) is selected from the group: molybdenum oxide, molybdenum salt, organic matter containing molybdenum, or combinations thereof；With

The component (c) is selected from the group: yttrium salt, yttrium oxide, or combinations thereof；

Further include following steps in the step (ii):

(ii-1) molybdenum (VI) in the component (b) is reduced to molybdenum (IV) under the action of reducibility gas；

(ii-2) molybdenum (IV) deposits on the bearing substrate, and reacts with gas phase sulphur source, thus described MoS is formed on bearing substrate₂；And pyrolysis occurs for the component (c), generates simple substance yttrium, yttrium Uniform Doped to institute The MoS stated₂In；With

(ii-3) cool down, to form composite coating as described in claim 1 on the bearing substrate；

Reaction temperature in step (ii-2) is 200~1200 DEG C；And/or the reaction time is 0.5-5 hours.

5. preparation method as described in claim 4, which is characterized in that the bearing substrate is selected from the group: glass, pottery Porcelain, stainless steel, silicon wafer, hard alloy, or combinations thereof.

6. a kind of workpiece, which is characterized in that be deposited with composite coating as described in claim 1 on the workpiece.

7. a kind of purposes of composite coating as described in claim 1, which is characterized in that the composite coating is used to include micro- Mechanical electronic equipment, industrial equipment, motor vehicles and aerospace equipment wear-and corrosion-resistant.