Systems and methods for electrodeposition of tungsten disulfide coatings

Abstract

Systems, methods, and apparatus for electrodepositing tungsten disulfide coatings are described. Electrodeposition of the coating includes connecting a power source to a substrate surface and to an electrode, immersing the substrate surface and the electrode in an aqueous solution, and forming a tungsten disulfide layer on the substrate surface. The surface has conductivity, and the power supply is a direct-current power supply. The aqueous solution comprises sodium pyrosulfite, sodium tungstate, a surfactant and a pH regulator. The tungsten disulfide layer is formed by applying a pulse current to the substrate surface and the electrode in the aqueous solution by a power source and maintaining the pulse current for a predetermined period of time.

Description

Technical Field

[0001] The present disclosure relates to the field of tungsten disulfide coatings, and more particularly, to systems and methods for electrodepositing tungsten disulfide coatings. Background Art

[0002] Tungsten disulfide is a dry film lubricating coating with desirable properties such as a low coefficient of friction, a high wear life, a high rated load, good lubricant affinity, and good chemical inertness. Tungsten disulfide coatings can be applied to a substrate by chemical deposition processes or physical deposition processes (including chemical vapor deposition, metal-organic chemical vapor deposition, and physical vapor deposition). These processes involve high cycle times and high costs for producing coated substrates.

[0003] Tungsten disulfide coatings can also be applied by casting an admixture of tungsten disulfide and a polymeric binder. These coatings are subject to degradation when exposed to high temperatures and may be incompatible with certain classes of wet lubricants. Accordingly, there is a need in the art to optimize the production of tungsten disulfide thin films on components where wet lubrication is inadequate or fails, for example, under high temperature oxidation conditions. Summary of the Invention

[0004] Systems, methods, and apparatuses according to the present disclosure provide for electrodepositing a tungsten disulfide coating on a surface of a component.

[0005] Advantageously, the electrodeposited tungsten disulfide coatings as described herein can enhance the wear resistance of bearing surfaces, enhance the tribological performance of components with or without wet lubricants, increase the operating temperature at which a component can operate, enhance the electrical and / or electronic performance of components, combinations thereof, etc. In some aspects, the tungsten disulfide coating enhances the resistance to the occurrence or effects of electrical discharges. For example, one or more layers of tungsten disulfide can provide semiconductor properties on other conductive surfaces of a component.

[0006] According to various aspects of the present disclosure, a method includes connecting a power source to a substrate surface and to an electrode, immersing the substrate surface and the electrode in an aqueous solution, and forming a tungsten disulfide layer on the substrate surface. The surface is conductive and the power source is a direct current power source. The aqueous solution includes sodium metabisulfite, sodium tungstate, a surfactant, and a pH regulator. The tungsten disulfide layer is formed by applying a pulsed current to the substrate surface and the electrode in the aqueous solution via the power source and maintaining the pulsed current for a predetermined period of time.

[0007] According to other aspects of the present disclosure, a pulsed current is applied to the substrate at a charge of 1 mA / cm 2 to 10 mA / cm 2 .

[0008] According to other aspects of the present disclosure, the predetermined time period is from 5 minutes to 20 minutes; and the pulsed current has a pulse frequency and a pulse duty cycle, the pulse frequency is less than 0.5 Hz, and the pulse duty cycle is less than 50%.

[0009] According to other aspects of the present disclosure, the pH regulator provides an aqueous solution with a pH value of 6.0 to 9.0.

[0010] According to other aspects of the present disclosure, the pH regulator provides an aqueous solution with a pH value of 6.0 to 7.5.

[0011] According to other aspects of the present disclosure, the pH regulator provides an aqueous solution with a pH value of 7.5 to 9.0.

[0012] According to other aspects of the present disclosure, the aqueous solution further contains at least 8 wt% of sodium metabisulfite, at least 2 wt% of sodium tungstate, and at least 8 wt% of a surfactant.

[0013] According to other aspects of the present disclosure, the aqueous solution further contains 9 wt% to 20 wt% of sodium metabisulfite, 4 wt% to 10 wt% of sodium tungstate, and 9 wt% to 20 wt% of a surfactant.

[0014] According to other aspects of the present disclosure, after the substrate is taken out of the aqueous solution, the thickness of the tungsten disulfide layer is 1 μm to 2 μm.

[0015] According to other aspects of the present disclosure, the surface is a black oxide layer deposited on the substrate.

[0016] According to other aspects of the present disclosure, the tungsten disulfide layer is a first tungsten disulfide layer, the first tungsten disulfide layer has a first morphology, the second tungsten disulfide layer has a second morphology different from the first morphology, and forming the coating surface further includes forming a second tungsten disulfide layer on the first tungsten disulfide layer. The second tungsten disulfide layer is formed by adjusting the pH value of the aqueous solution, applying a second pulsed current to the first tungsten disulfide layer and the electrode in the aqueous solution, and maintaining the pulsed current for a second predetermined time period. The second pulsed current is applied by a power supply.

[0017] According to various aspects of the present disclosure, the component includes a coating surface formed by connecting the surface of the component to a power supply, immersing the surface and the electrode in an aqueous solution, and forming a tungsten disulfide layer on the surface. The surface has conductivity, and the power supply is a DC power supply. The aqueous solution contains sodium metabisulfite, sodium tungstate, a surfactant, and a pH regulator. The tungsten disulfide layer is formed by applying a pulsed current to the surface and the electrode in the aqueous solution via the power supply and maintaining the pulsed current for a predetermined time period. Applying the pulsed current causes the substrate to act as an anode.

[0018] According to other aspects of the present disclosure, at 1 mA / cm2 to 10 mA / cm 2 Apply a pulsed current to the substrate with an electric charge of

[0019] According to other aspects of the present disclosure, the pH regulator provides an aqueous solution with a pH value of 6.0 to 7.5.

[0020] According to other aspects of the present disclosure, the aqueous solution further contains sodium metabisulfite with a content of 9 wt% to 20 wt%, sodium tungstate with a content of 4 wt% to 10 wt%, and a surfactant with a content of 9 wt% to 20 wt%.

[0021] According to other aspects of the present disclosure, the tungsten disulfide layer is a first tungsten disulfide layer having a first morphology, the second tungsten disulfide layer has a second morphology different from the first morphology, and forming the coating surface further includes forming a second tungsten disulfide layer on the first tungsten disulfide layer. The second tungsten disulfide layer is formed by adjusting the pH value of the aqueous solution, applying a second pulsed current to the first tungsten disulfide layer and the electrode in the aqueous solution, and maintaining the pulsed current for a second predetermined period of time. The second pulsed current is applied by a power supply.

[0022] According to various aspects of the present disclosure, a vehicle includes a first component movably engaged with a second component. The first component includes a coating surface in contact with the second component. The coating surface is formed by connecting the surface of the component to a power supply, immersing the surface and the electrode in an aqueous solution, and forming a tungsten disulfide layer on the surface. The surface has electrical conductivity, and the power supply is a DC power supply. The aqueous solution contains sodium metabisulfite, sodium tungstate, a surfactant, and a pH regulator. The tungsten disulfide layer is formed by applying a pulsed current to the surface and the electrode in the aqueous solution via the power supply and maintaining the pulsed current for a predetermined period of time to form the coating surface. Applying the pulsed current causes the substrate to act as an anode.

[0023] According to other aspects of the present disclosure, the pH regulator provides an aqueous solution with a pH value of 6.0 to 7.5.

[0024] According to other aspects of the present disclosure, the aqueous solution further contains sodium metabisulfite with a content of 9 wt% to 20 wt%, sodium tungstate with a content of 4 wt% to 10 wt%, and a surfactant with a content of 9 wt% to 20 wt%.

[0025] According to other aspects of the present disclosure, the tungsten disulfide layer is a first tungsten disulfide layer having a first morphology, the second tungsten disulfide layer has a second morphology different from the first morphology, and forming the coating surface further includes forming a second tungsten disulfide layer on the first tungsten disulfide layer. The second tungsten disulfide layer is formed by adjusting the pH value of the aqueous solution, applying a second pulsed current to the first tungsten disulfide layer and the electrode in the aqueous solution, and maintaining the pulsed current for a second predetermined period of time. The second pulsed current is applied by a power supply.

[0026] The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are illustrative and are not intended to limit the subject matter defined by the claims. Exemplary aspects are discussed in the following detailed description and are shown in the accompanying drawings, in which:

[0028] Figure 1 An electrodeposition system for producing a component having a tungsten disulfide coating according to various aspects of the present disclosure is shown;

[0029] Figure 2 An example method of electrodepositing a tungsten disulfide layer on a component according to various aspects of the present disclosure is shown;

[0030] Figure 3 shows a BED-C image of a first tungsten disulfide layer according to various aspects of the present disclosure;

[0031] Figure 4 shows a BED-C image of a second tungsten disulfide layer according to various aspects of the present disclosure;

[0032] Figure 5 shows a BED-C image of a third tungsten disulfide layer according to various aspects of the present disclosure;

[0033] Figure 6 shows a BED-C image of a fourth tungsten disulfide layer according to various aspects of the present disclosure; and

[0034] Figure 7 Shows Figure 6 Schematic diagram of the SEM image. DETAILED DESCRIPTION

[0035] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the foregoing technical field, background technology, summary of the invention or the following detailed description.

[0036] Figure 1 An electrodeposition system 100 for producing a component having a tungsten disulfide coating is shown. The system includes a component 102, an electrode 104, and an aqueous solution 106 in a container 108. The system 100 also includes a power source 110 connected to the component 102 and the electrode 104 via, for example, wires.

[0037] Component 102 is an article or a part thereof that can be optimized with a tungsten disulfide layer. Component 102 includes a substrate 112 and a surface 114. The substrate 112 can be conductive, semi-conductive, or insulating. In some aspects, the substrate 112 is a pure metal or an alloy metal or includes a pure metal or an alloy metal. For example, the substrate 112 can be or include Babbitt metals (such as lead Babbitt alloys and tin Babbitt alloys), bearing metals (such as 52100 steel), stainless steel, aluminum, aluminum alloys, bronze, brass, their alloys, their combinations, etc. The substrate 112 can be the entire component and / or at least one layer of coating on component 102.

[0038] The surface is configured to receive a tungsten disulfide layer. The surface is conductive and electrically connected to a power source. In some aspects, the surface 114 is electrically connected to the power source via the substrate 112. In some aspects, the surface 114 is electrically connected to the power source while the substrate 112 is not electrically connected to the power source.

[0039] The surface can include one or more features configured to optimize the properties of the applied tungsten disulfide layer. For example, mechanical processes and / or chemical processes can be applied to the surface 114 prior to electrodeposition to provide surface features that optimize the properties of the applied tungsten disulfide layer. Optimized properties can include, for example, surface roughness, surface geometry, atomic composition, etc. For example, the surface 114 can be doped or coated with a passivating agent to inhibit chemical changes or dimensional changes at the surface 114. In some aspects, the surface 114 includes a black oxide (Fe 3 O 4 ) layer. In some aspects, the thickness of the black oxide layer is from 1 μm to 2 μm.

[0040] In some aspects, component 102 is incorporated into a vehicle, such as an electric vehicle. Component 102 can be, for example, a bearing component or a slidable component. Exemplary bearing components include journal bearings, roller bearings, ball bearings, linear bearings, their combinations, etc. For example, component 102 can be a bearing configured to support a rotatable shaft or a part thereof. The bearing can include, for example, raceways (such as an inner raceway and an outer raceway), rollers (such as cylindrical, spherical, needle, or tapered rollers), and bearing surfaces (such as an inner bearing surface and an outer bearing surface), and the tungsten disulfide coating can be applied to one or more selected components or to each component.

[0041] Exemplary slidable components include actuator pins (e.g., turbocharger wastegate pins or boom pins), intake valves, exhaust valves, pulleys, etc. The tungsten disulfide layer can be selectively coated onto certain bearing surfaces of the slidable component, while other bearing surfaces do not include the coating. For example, the tungsten disulfide layer can be deposited on surfaces configured for sliding with adjacent components, rather than on surfaces configured to form a seal with adjacent components.

[0042] The electrode 104 allows current to pass through the surface 114 of the component 102 during electrodeposition. The electrode 104 includes a compatible material resistant to electrochemical oxidation. The compatible material can be or include, for example, stainless steel alloys (such as 304L), noble metal (such as platinum, rhodium, indium) clad titanium, inert materials, combinations thereof, etc. The electrode 104 can also include a shaped surface configured to enhance the uniformity of the coated tungsten disulfide layer. For example, the shaped surface can be complementary to the shape defined by the surface 114 of the component 102.

[0043] The power supply is configured to provide a desired current to the component 102 and the electrode 104 to produce an electrodeposited tungsten disulfide layer on the component 102. The power supply can include or be connected to a controller configured to control the actuation and / or operation of the power supply. For example, the controller can be configured to provide at least one desired operating parameter by monitoring and / or controlling values of one or more values functionally related to the desired operating parameter. In some aspects, the target operating parameter can be a desired current density, and the controller can vary the applied voltage to provide the desired current density.

[0044] The power supply can be, for example, a direct current power supply configured to provide direct current. In some aspects, the power supply can also be configured to provide pulsed current. The pulsed current can be, for example, intermittently applied current, reverse flow of current, combinations thereof, etc. The pulsed current includes a pulse frequency and a pulse duty cycle. The pulse frequency is the duration of the period, and the pulse duty cycle is the portion of the period that includes the applied current and / or non-reversed current.

[0045] The aqueous solution 106 contains an ionic sulfur source, an ionic tungsten source, a surfactant, and an optional pH regulator.

[0046] The ionic tungsten source is configured to provide tungsten to the electrodeposited tungsten disulfide layer. In some aspects, the ionic tungsten source is sodium tungstate. Although not bound by theory, it is believed that tungstate ions (WO 4 2-) provides beneficial kinetic and / or thermodynamic properties for optimizing the deposited tungsten disulfide layer. In some aspects, the portion of the ionic tungsten source is selected based on the portion of the ionic sulfur source to further optimize the deposited tungsten disulfide layer. Although not bound by theory, the content of the ionic tungsten source is higher than the content at which tungsten disulfide is deposited at a desired rate during operation and lower than the content that promotes defects (such as pure metal defects) in the deposited layer. In some aspects, the content of the ionic tungsten source is at least 2 wt%. In some other aspects, the content of the ionic tungsten source is 4 wt% to 10 wt%.

[0047] The ionic sulfur source is configured to provide sulfur for electrodepositing the tungsten disulfide layer. In some aspects, the ionic sulfur source is sodium metabisulfite. Although not bound by theory, it is believed that the bisulfite ions (HSO 3 - ) provide beneficial kinetic and / or thermodynamic properties that optimize the properties of the deposited tungsten disulfide layer.

[0048] Although not bound by theory, the content of the ionic sulfur source is higher than the content that promotes the deposition of tungsten disulfide at a desired rate in combination with the ionic tungsten source during operation and lower than the content that promotes defects in the deposited layer. In some aspects, the content of the ionic sulfur source is at least 8 wt%. In some other aspects, the content of the ionic sulfur source is 9 wt% to 20 wt%.

[0049] The surfactant is configured to reduce the surface tension between the aqueous solution 106 and the surface 114 of the component 102. The surface tension is selected to optimize the geometry of the bubbles 116 generated on the surface 114 of the component 102 during electrodeposition.

[0050] In some aspects, the surfactant is an anionic surfactant. The anionic surfactant may include a head with one or more tails. The head can be an anionic functional group. The anionic functional group may include, for example, sulfate, sulfonate, phosphate, carboxylate, combinations thereof, etc. The tail can be a hydrocarbon chain. These chains can be straight or branched and can be aliphatic or aromatic chains. The anionic surfactant can be, for example, TEEPOL TM 610S.

[0051] The content of the surfactant is sufficient to provide a desired bubble 116 geometry during the electrodeposition of the tungsten disulfide layer. In some aspects, the content of the surfactant is at least 8 wt%. In other aspects, the content of the surfactant is 9 wt% to 20 wt%.

[0052] A pH regulator is added to the aqueous solution 106 to bring the pH value of the aqueous solution 106 to a desired level. In some aspects, the pH value of the aqueous solution 106 is 6.0 to 9.0.

[0053] The pH value is selected to provide a desired morphology of the electrodeposited tungsten disulfide layer. In some aspects, the pH value of the aqueous solution 106 is selected to provide a first morphology that optimizes tribological properties. For example, the first morphology can be a randomly oriented morphology that optimizes dry lubrication and / or the retention of a lubricating fluid within the voids between tungsten disulfide particles (such as platelets or nanosheets of tungsten disulfide). In some other aspects, the value of pH of the aqueous solution 106 is selected to provide a second morphology that optimizes electronic properties. For example, the second morphology can be a two-dimensional ordered morphology that provides semiconductor properties with a desired bandgap. In some aspects, the bandgap is at least 1.32 eV. In some other aspects, the bandgap is 2.03 eV. Advantageously, the bandgap can be selected to optimize the lifespan of the component 102 and / or the tungsten disulfide layer when the component is exposed to parasitic currents generated by, for example, an electric drive unit.

[0054] The first morphology can be generated or optimized by, for example, adjusting the pH value of the aqueous solution 106 to between 6.0 and 7.5. In some examples, the first morphology optimizes tribological properties by being configured in a randomly ordered morphology. The randomly ordered morphology can include randomly ordered platelets or nanosheets of tungsten disulfide.

[0055] The second morphology can be generated or optimized by, for example, adjusting the pH value of the aqueous solution 106 to between 7.5 and 9.0. In some examples, the second morphology optimizes electronic properties by being configured as a two-dimensional ordered morphology. The two-dimensional ordered morphology can include at least one tungsten disulfide crystal having a substantially planar microstructure. In some aspects, the tungsten disulfide layer includes multiple monolayers, each monolayer including a two-dimensional ordered morphology.

[0056] The pH regulator can be an acid or a base. Acidic pH regulators can include, for example, citric acid (HOC(CO 2 H)(CH 2 CO 2 H) 2 ), ascorbic acid (C 6 H 8 O 6 ), acetic acid (CH 3 COOH), tartaric acid (2,3-dihydroxybutanedioic acid), phosphoric acid (H 3 PO 4 ), sulfuric acid (H 2 SO 4 ), combinations thereof, and the like. Basic pH regulators can include, for example, pyridine (C 5 H 5 N), methylamine (CH 3 NH 2 ), imidazole (C 3 N 2 H 4 ), benzimidazole (C 7 H6 N 2 )), ammonia (NH 3 ), inorganic hydroxides (such as NaOH, KOH, Mg(OH) 2 ), etc.), combinations thereof, etc.

[0057] Figure 2 An example method 200 for electrodepositing a tungsten disulfide layer on a component is shown. At block 202, a power source is connected to surface 114 of substrate 112 and to electrode 104. Surface 114 may optionally be cleaned and / or treated to provide one or more desired surface characteristics. For example, chemical processes and / or physical processes may be used to treat surface 114, which processes provide desired surface features to optimize the characteristics of the tungsten disulfide coating. Desired surface features may be desired roughness, morphology, or chemical properties. In some aspects, surface 114 is treated to optimize the current distribution on surface 114, thereby optimizing the desired characteristics of the resulting tungsten disulfide coating. In some aspects, surface 114 is treated to optimize the interface between substrate 112 and the resulting tungsten disulfide layer.

[0058] In block 204, surface 114 of substrate 112 and electrode 104 are immersed in aqueous solution 106. Then at block 206, a tungsten disulfide layer is formed. Forming the tungsten disulfide layer includes applying a pulsed current (at block 208), and maintaining the pulsed current for a predetermined period of time (at block 210).

[0059] When immersed in aqueous solution 106, a pulsed current is applied to surface 114 of substrate 112 and to electrode 104. When applied, the current causes electrode 104 to act as an anode and surface 114 to act as a cathode. The characteristics of the pulsed current can be selected and maintained to provide the desired grain characteristics of the deposited tungsten disulfide layer. These characteristics can include, for example, current density, pulse frequency, and pulse duty cycle.

[0060] The current density can be selected, for example, to optimize the deposition flux and / or uniformity of the tungsten disulfide layer. In some aspects, the current density is 1 mA / cm 2 to 10 mA / cm 2 . The pulsed current is at least partially selected to provide a desired flux of tungsten disulfide deposited on surface 114. For example, while not being bound by theory, it is believed that currents below 1 mA / cm 2 may require impractically long periods of time to deposit the tungsten disulfide layer, or may not deposit the tungsten disulfide layer with the desired morphology and / or uniformity. In other examples, while not being bound by theory, it is believed that currents above 10 mA / cm 2 promote an increase in defects in the tungsten disulfide lattice, a decrease in the uniformity of the desired morphology, and / or the deposition of pure tungsten grains on or within surface 114.

[0061] The pulse frequency can be selected to optimize, for example, the crystal size of the tungsten disulfide layer. In some aspects, the pulse frequency is less than 0.5 Hz (for example, the pulse period can repeat every two seconds or longer). In some other aspects, the pulse frequency is less than 0.34 Hz (for example, the pulse period can repeat every three seconds or longer).

[0062] The pulsed current can be applied with a pulse duty cycle selected to optimize the surface 114 quality of the tungsten disulfide layer by optimizing, for example, the nucleation rate, grain growth and shaping, and grain refinement.

[0063] In some aspects, the pulse duty cycle is less than 50%. For example, for a two - second pulse period, a current can be applied for one second and no current for one second. In some other aspects, the pulse duty cycle is less than 34%. For example, for a three - second pulse period, a current can be applied for one second and no current for two seconds.

[0064] A predetermined time period is selected to provide a tungsten disulfide layer of a predetermined thickness under the selected operating parameters. In some aspects, the thickness is from 1 μm to 2 μm. In some aspects, the predetermined time period is from 5 minutes to 20 minutes.

[0065] In some aspects, a first tungsten disulfide layer is deposited in a first morphology on top of a second tungsten disulfide layer deposited in a second morphology. Advantageously, the multi - layer tungsten disulfide layer can optimize the electronic and tribological properties of the component 102. In some other aspects, the first tungsten disulfide layer and the second tungsten disulfide layer can be deposited using the same aqueous solution 106. For example, the first tungsten disulfide layer can be deposited at a first pH value, and then a pH regulator can be added to the aqueous solution 106 to change the pH value to a second pH value for depositing the second layer.

[0066] In some aspects, the method repeats block 206 to form at least one additional tungsten disulfide layer on top of the previous tungsten disulfide layer. Before applying a second pulsed current at block 208 and maintaining the second pulsed current for a second predetermined time period at block 210, the pH value of the aqueous solution can be adjusted to a second pH value. The pH value can be adjusted such that the first tungsten disulfide layer and the second tungsten disulfide layer have different morphologies.

[0067] Optionally, the aqueous solution can be adjusted during the formation of the tungsten disulfide layer to optimize the uniformity or other properties of the tungsten disulfide layer. The adjustment can include, for example, maintaining the temperature, stirring, or composition of the aqueous solution 106.

[0068] Although not bound by theory, it is believed that the electrodeposition of the tungsten disulfide layer in method 200 proceeds through the following reaction:

[0069]

[0070]

[0071]

[0072] Figures 3-6 shows a synthetic image of a backscattered electron detector of a scanning electron microscope ("BED-C image"), e.g., a tungsten disulfide layer electrodeposited on bearing steel.

[0073] Figure 3 shows the BED-C image of the first tungsten disulfide layer formed with the aqueous solution 106 having a pH value of 6.5 by the above system and method. The aqueous solution 106 is 10 wt% sodium metabisulfite, 5 wt% sodium tungstate, and 10 wt% TEEPOL TM 610S. The DC power supply is configured to apply a current of 3 mA / cm 2 to the sample, and a floating voltage to maintain the applied current. The DC power supply is also configured to pulse-apply the current at a pulse frequency of 0.33 Hz and a pulse duty cycle of 0.33. The image was generated at a high vacuum using an acceleration voltage of 15.0 kV and magnified 5,000 times.

[0074] Figure 4 shows the BED-C image of the second tungsten disulfide layer formed with the aqueous solution 106 having a pH value of 6.5 by the above system and method. The aqueous solution 106 is 10 wt% sodium metabisulfite, 5 wt% sodium tungstate, and 10 wt% TEEPOL TM 610S. The DC power supply is configured to apply a current of 3 mA / cm 2 to the sample, and a floating voltage to maintain the applied current. The DC power supply is also configured to pulse-apply the current at a pulse frequency of 0.33 Hz and a pulse duty cycle of 0.33. The image was generated using an acceleration voltage of 10.0 kV and magnified 10,000 times.

[0075] Figure 5 shows the BED-C image of the tungsten disulfide layer formed with the aqueous solution 106 having a pH value of 8.5 by the above system and method. The aqueous solution 106 is 10 wt% sodium metabisulfite, 5 wt% sodium tungstate, and 10 wt% TEEPOL TM 610S. The DC power supply is configured to apply a current of 3 mA / cm 2 to the sample, and a floating voltage to maintain the applied current. The DC power supply is also configured to pulse-apply the current at a pulse frequency of 0.33 Hz and a pulse duty cycle of 0.33. The image was generated using an acceleration voltage of 10.0 kV and magnified 5,000 times.

[0076] Figure 6 andFigure 7 Image 600 and schematic diagram 700 showing a cross-section of tungsten disulfide layer 602 formed from aqueous solution 106 with a pH of 8.5 by the above-described system and method are presented. Figure 6 It is a BED-C image generated at an acceleration voltage of 20.0 kV under high vacuum and magnified 7,000 times. Cross-section 600 shows tungsten disulfide layer 602, black oxide layer 604, and substrate 606. Black oxide layer 604 is measured to be approximately 1.185 μm at indicator 702, approximately 1.261 μm at indicator 704, and approximately 1.815 μm at indicator 706. Tungsten disulfide layer 602 is measured to be approximately 1.624 μm at indicator 708, approximately 1.509 μm at indicator 710, and approximately 1.226 μm at indicator 712. Advantageously, it can be seen that electrodepositing a tungsten disulfide layer can provide a surface with reduced roughness compared to a base layer (such as substrate 602).

[0077] As will be understood by those skilled in the art, the present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments have been shown by way of example in the drawings and described in detail above. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the drawings. On the contrary, the present disclosure encompasses modifications, equivalents, combinations, sub-combinations, arrangements, groupings, and alternatives that fall within the scope and spirit of the present disclosure and are defined by the appended claims.

[0078] As used herein, unless the context clearly dictates otherwise, the words "and" and "or" shall be both conjunctive and disjunctive; unless the context clearly dictates otherwise, the word "all" means "any and all"; the word "any" means "any and all"; the word "comprising" means "including but not limited to"; and the singular forms "a", "an", and "the" include plural referents and vice versa.

[0079] The numerical values of the parameters (such as quantities or conditions) in this specification shall be understood to be modified by the term "about", whether or not "about" actually appears before the numerical value, unless otherwise explicitly or clearly indicated according to the context (including the appended claims). The numerical parameters set forth herein and in the appended claims are approximations, which may vary depending on the desired characteristics sought to be obtained by the present disclosure. At a minimum, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed at least in accordance with the number of significant digits reported and by applying ordinary rounding techniques.

[0080] Approximating words such as "approximately", "about", "substantially", etc. may be used herein in the sense of "at, close to, or nearly at", "within 0 - 10% of", or "within acceptable manufacturing tolerances", or logical combinations thereof, for example.

[0081] Although the scope and bounds of the term "about" are readily understood by one of ordinary skill in the art, the term "about" indicates that the recited numerical value or property admits of imprecision. If the imprecision provided by "about" is not understood in the art to have this ordinary meaning, then "about" at least indicates the variation that may arise from the ordinary methods of measuring and using such parameters. For example, if not otherwise understood in the art, the term "about" means within 10% (such as ±10%) of the recited value.

[0082] Although the scope and bounds of the term "substantially" are readily understood by one of ordinary skill in the art, the term "substantially" indicates that the recited numerical value or property admits of some imprecision. If the imprecision provided by "substantially" is not understood in the art to have this ordinary meaning, then "substantially" at least indicates the variation that may arise from manufacturing processes and the measurement of these parameters. For example, if not otherwise understood in the art, the term "substantially" means within 5% (such as ±5%) of the recited value.

[0083] Although the scope and bounds of the term "substantially" are readily understood by one of ordinary skill in the art, the term "substantially" indicates that the recited numerical value or property admits of some minor imprecision. If the imprecision provided by "substantially" is not understood in the art to have this ordinary meaning, then "substantially" indicates at least a negligible variation in the desired parameter that may not be overcome. For example, if not otherwise understood in the art, the term "substantially" means within 1% (such as ±1%) of the recited value.

[0084] Although the scope and bounds of the term "pure" are readily understood by one of ordinary skill in the art, the term "pure" indicates that a compound may include very small amounts of other materials. If the imprecision provided by "pure" is not understood in the art to have this ordinary meaning, then "pure" at least indicates the variation that may arise from separation processes and the measurement of these parameters. For example, if not otherwise understood in the art, the term "pure" means greater than 99.9% of the recited material.

[0085] It should be understood that the ranges provided herein include the recited range, sub - ranges within the recited range, and each value within the recited range.

[0086] Although the best mode for carrying out the present disclosure has been described in detail, those skilled in the art familiar with the field to which the present disclosure pertains will recognize various alternative designs and embodiments for practicing the present disclosure within the scope of the appended claims.

[0087] Although the best mode for carrying out the present disclosure has been described in detail, those skilled in the art to which the present disclosure pertains will recognize various alternative designs and embodiments for practicing the present disclosure within the scope of the appended claims.

Claims

1. A method comprising: connecting a power source to the substrate surface and to the electrode, the surface being conductive, the power source being a direct current power source; immersing the substrate surface and the electrode in an aqueous solution comprising sodium pyrosulfite, sodium tungstate, a surfactant, and a pH adjuster; and A tungsten disulfide layer is formed on the surface of the substrate, wherein the tungsten disulfide layer is formed on the surface of the substrate by the following method: applying a pulse current to the substrate surface and the electrode in the aqueous solution via the power source; as well as The pulse current is maintained for a predetermined period of time.

2. The method according to claim 1, wherein the pH adjuster provides the aqueous solution with a pH value of 6.0 to 9.

0.

3. The method according to claim 2, wherein the pH adjuster provides the aqueous solution with a pH value of 6.0 to 7.

5.

4. The method according to claim 2, wherein the aqueous solution further comprises: Sodium metabisulfite in an amount of at least 8 wt%, Sodium tungstate in an amount of at least 2 wt%, and A surfactant content of at least 8 wt %.

5. The method according to claim 2, wherein the aqueous solution further comprises: Sodium metabisulfite in an amount of 9 wt % to 20 wt %, Sodium tungstate in an amount of 4wt% to 10wt%, and The content is 9wt% to 20wt% of surfactant. 6 . The method according to claim 1 , wherein after the substrate is taken out from the aqueous solution, the thickness of the tungsten disulfide layer is 1 μm to 2 μm. The method of claim 1 , wherein the surface is a black oxide layer deposited on the substrate.

8. The method according to claim 1, wherein the tungsten disulfide layer is a first tungsten disulfide layer, the first tungsten disulfide layer has a first morphology, and the second tungsten disulfide layer has a second morphology different from the first morphology, and the method further comprises: A second tungsten disulfide layer is formed on the first tungsten disulfide layer, wherein the second tungsten disulfide layer is formed on the first tungsten disulfide layer in the following manner: adjusting the pH value of the aqueous solution; applying a second pulse current to the first tungsten disulfide layer in the aqueous solution and the electrode via the power supply; and The pulse current is maintained for a predetermined period of time.

9. A component comprising: A coating surface, wherein the coating surface is formed by: connecting a surface of the component to a power source, wherein the surface is conductive and the power source is a direct current power source; immersing the surface and the electrode in an aqueous solution comprising sodium metabisulfite, sodium tungstate, a surfactant, and a pH adjuster; and A tungsten disulfide layer is formed on the surface, wherein the tungsten disulfide layer is formed on the surface by the following method: applying a pulse current to the surface and the electrode in the aqueous solution via the power source so that the substrate acts as an anode; as well as The pulse current is maintained for a predetermined period of time.

10. A vehicle comprising: A first component, the first component is movably engaged with a second component, the first component includes a coating surface in contact with the second component, and the coating surface is formed by: connecting a surface of the component to a power source, wherein the surface is conductive and the power source is a direct current power source; immersing the surface and the electrode in an aqueous solution comprising sodium metabisulfite, sodium tungstate, a surfactant, and a pH adjuster; and A tungsten disulfide layer is formed on the surface, and the tungsten disulfide layer is formed on the surface by the following method: applying a pulse current to the surface and the electrode in the aqueous solution via the power source so that the substrate acts as an anode; as well as The pulse current is maintained for a predetermined period of time, thereby forming the coating surface.

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