Process for the preparation of a wear-resistant reinforced self-lubricating sulfur-based film

Abstract

The application relates to a preparation process of a wear-resistant reinforced self-lubricating sulfur-based film, which comprises the following steps: firstly, titanium dioxide (TiO2) sol is prepared by using titanium dioxide (TiO2) powder; secondly, an activated iron-carbon alloy is put into a composite plating solution containing the titanium dioxide (TiO2) sol and is subjected to water bath heating treatment; and finally, a wear-resistant reinforced sulfur-based lubricating film is prepared on the surface of the iron-carbon alloy through a post-treatment process. The application aims to solve the problems of poor mechanical performance of a traditional plating layer, easy occurrence of large cracks and insufficient tribological performance of the plating layer under heavy load working conditions, and the mechanical strength and wear resistance of the prepared sulfur-based lubricating film are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of mechanical basic friction surface treatment technology, specifically relating to a preparation process of a wear-resistant and enhanced self-lubricating sulfur-based film. Background Technology

[0002] According to scientific statistics, 70% to 80% of the energy of various machines is consumed due to friction during operation. This not only wastes resources but also exacerbates fatigue wear, significantly reducing machine safety and service life. With the continuous development of science and technology and the expansion of production fields, people have gradually realized the importance of friction reduction and lubrication. Surface engineering technology is a very important friction reduction method. FeS lubricating films and Ni-P wear-resistant films, which have emerged in recent years, can effectively improve tribological properties. However, under some heavy-load environments, insufficient mechanical strength of the film causes premature film detachment, resulting in less than ideal tribological effects. For example, research has found that FeS films can improve lubrication and prevent seizing or scratching of friction surfaces during operation. However, under some high-load conditions, its internal phase structure changes, increasing the coefficient of friction of the friction surface. The FeS film then quickly peels off or adheres to other workpiece surfaces, greatly reducing its friction-reducing effect. To improve the mechanical properties of the film, a common method is to add hard nanoparticles to the film. Examples include a Ni-P-TiO2 composite plating solution formulation and plating process for copper alloy surfaces, and another Ni-P-PTFE-TiO2 composite nanocoating. These inventions lay the research foundation for the preparation of high-performance Ni-P-TiO2 composite coatings. Because titanium dioxide (TiO2) nanoparticles have high surface energy, they are very prone to agglomeration. This results in uneven distribution of TiO2 nanoparticles in the coating, easily inducing numerous surface cracks. When the number of cracks reaches a certain level, the substrate is exposed, affecting the mechanical properties and lubrication effect of the film. How to solve the problem of nanoparticle dispersion and develop hard-reinforced self-lubricating films remains to be explored. Summary of the Invention

[0003] To improve the mechanical strength and wear resistance of soft sulfur-based films, solve the problems of poor mechanical properties and easy occurrence of large cracks in traditional coatings, and make up for the insufficient tribological properties of coatings under heavy load conditions, this invention provides a preparation process for wear-resistant and enhanced self-lubricating sulfur-based films.

[0004] The preparation steps of a wear-resistant and enhanced self-lubricating sulfur-based film are as follows:

[0005] (1) Preparation of titanium dioxide sol

[0006] 10g of titanium dioxide (TiO2) powder was added to 150mL of anhydrous ethanol, the pH was adjusted to 3 with nitric acid, the mixture was heated to 70℃ in a water bath and stirred at 4500r / min for 40 min, and then allowed to stand and age for 72 h to obtain a light yellow titanium dioxide (TiO2) sol.

[0007] (2) Preparation of activated iron-carbon alloy materials

[0008] The surface of the iron-carbon alloy material was polished with 180-grit, 400-grit, and 2000-grit sandpaper respectively to obtain an iron-carbon alloy material with a bright metallic luster.

[0009] Immerse and pickle in a 2% hydrochloric acid solution for 20-30 seconds;

[0010] The material is activated in a 3%–5% hydrochloric acid solution for 10–15 seconds, rinsed with deionized water, vacuum dried, and then baked to obtain the activated iron-carbon alloy material.

[0011] (3) Preparation of plated parts

[0012] Mix 2–5 g of thioacetamide, 3–5 g of sodium thiosulfate, 5–8 g of ferrous chloride, 0.5–1 g of acid, 1–2 g of graphite powder, 0.2–0.6 g of sodium hydroxide, 0.01–0.02 mg of sodium dodecyl sulfate, 20–50 mL of titanium dioxide sol, and 100 mL of deionized water evenly to obtain a composite plating solution.

[0013] The acid is one of maleic acid, citric acid, or glycine;

[0014] The activated iron-carbon alloy material was placed in the composite plating solution, heated to 50°C in a water bath, and magnetic stirring was turned on. The plating time was 120 minutes to obtain the plated part.

[0015] (4) Post-processing

[0016] The plated parts are placed in a resistance furnace and heat-treated at 300°C for 1 hour under a nitrogen protective atmosphere. Then, they are placed in lubricating oil and cooled to room temperature. The resulting plated parts have a wear-resistant and enhanced self-lubricating sulfur-based film on their surface.

[0017] The wear-resistant and enhanced self-lubricating sulfur-based film is in the shape of stacked sheet-like iron sulfide (FeS), with titanium dioxide (TiO2) nanoparticles densely and uniformly filling the gaps between the stacked iron sulfide (FeS). The thickness of the self-lubricating sulfur-based film is 15~20μm, and the hardness is 350~500HV.

[0018] The self-lubricating sulfur-based film contains 40%~60% iron, 15%~30% sulfur, 5%~15% titanium, 10%~18% oxygen, and 3%~8% carbon by mass.

[0019] In step (1), the particle size of titanium dioxide (TiO2) powder is 400~450nm.

[0020] Compared with existing technologies, the beneficial technical effects of the present invention are reflected in the following aspects:

[0021] 1. The process of the present invention uses a nano-hard phase for reinforcement. The nanoparticles are added to the chemical plating solution and co-deposited with the plating solution to obtain a hard-reinforced self-lubricating film. The hard nanoparticles are uniformly dispersed and embedded in the soft sulfur-based self-lubricating film. The resulting composite coating has good mechanical strength and lubrication stability and is suitable for heavy-load friction conditions.

[0022] 2. This invention is based on the design concept of soft and hard composite thin film materials. Titanium dioxide (TiO2) nanoparticles are added in sol form. The titanium dioxide nanoparticles are dispersed and filled in the gaps between the sheet-like ferrous sulfide (FeS). At the same time, the soft sulfur-based self-lubricating film easily encapsulates the hard titanium dioxide nanoparticles, effectively avoiding coating cracks and making the coating and substrate more tightly bonded, less prone to frictional detachment. Simultaneously, the high-temperature post-treatment releases the stress around the hard particles, solving the problems of titanium dioxide (TiO2) nanoparticle agglomeration and stress concentration. The hard ions and soft lubricating phase in the coating exert a good synergistic effect of friction reduction and wear resistance, improving the mechanical strength of the coating and enhancing the working performance and life of the sulfur-based lubricating film thin film.

[0023] 3. This invention uses sol technology to prepare titanium dioxide sol. Adding the titanium dioxide sol to the plating solution allows the titanium dioxide nanoparticles to be uniformly dispersed in the plating solution, making them less prone to agglomeration. The hard ions and soft lubricating phases in the coating layer exert a good synergistic effect in reducing friction and wear resistance. Compared with traditional sulfur-based films, the hardness of the enhanced sulfur-based film is increased by 23.1%~23.9%, the wear track depth is reduced by 12.5%~50%, and the coefficient of friction is reduced by 6.67%~16.67%. Detailed Implementation

[0024] The present invention will be further illustrated by the following embodiments.

[0025] Example 1

[0026] The preparation steps of a wear-resistant and enhanced self-lubricating sulfur-based film are as follows:

[0027] (1) Preparation of titanium dioxide sol

[0028] 10g of titanium dioxide (TiO2) powder was added to 150mL of anhydrous ethanol, the pH was adjusted to 3 with nitric acid, the mixture was heated to 70℃ in a water bath and stirred at 4500r / min for 40min, and then allowed to stand for 72h to obtain a light yellow titanium dioxide sol.

[0029] (2) Preparation of activated iron-carbon alloy materials

[0030] The surface of the iron-carbon alloy material was polished with 180-grit, 400-grit, and 2000-grit sandpaper respectively to obtain an iron-carbon alloy material with a bright metallic luster.

[0031] Immerse in a 2% hydrochloric acid solution for 25 seconds;

[0032] The material was activated in a 3%–5% hydrochloric acid solution for 12 seconds, rinsed with deionized water, vacuum dried, and then baked to obtain the activated iron-carbon alloy material.

[0033] (3) Preparation of plated parts

[0034] 3g thioacetamide, 4g sodium thiosulfate, 7g ferrous chloride, 0.6g citric acid, 1.5g graphite powder, 0.5g sodium hydroxide, 0.015 mg sodium dodecyl sulfate, 20 mL titanium dioxide sol and 100 mL deionized water were mixed evenly to obtain a composite plating solution.

[0035] The activated iron-carbon alloy material was placed in the composite plating solution, heated to 50°C in a water bath, and magnetic stirring was turned on. The plating time was 120 minutes to obtain the plated part.

[0036] (4) Post-processing

[0037] The plated parts are placed in a resistance furnace and heat-treated at 300°C for 1 hour under a nitrogen protective atmosphere. Then, they are placed in lubricating oil and cooled to room temperature. The resulting plated parts have a wear-resistant and enhanced self-lubricating sulfur-based film on their surface.

[0038] The self-lubricating sulfur-based film has a thickness of 15 μm and contains 56% iron, 24% sulfur, 7% titanium, 6% oxygen, and 7% carbon by mass.

[0039] The frictional properties of the obtained specimens were determined using a face friction and wear tester. The initial load was set to 1000 N, and after running for 10 minutes, it was increased by 500 N. The entire process lasted 30 minutes, and the test rotation speed was 720 r / min. The surface hardness was directly measured using a Vickers hardness tester.

[0040] The self-lubricating sulfur-based film obtained in Example 1 has a hardness of 350 HV, a friction coefficient of 0.025, and a wear track depth of 0.012 mm.

[0041] Example 2

[0042] In step (1), the difference from Example 1 is that the mass of titanium dioxide (TiO2) powder is 12g;

[0043] Step (2) is the same as step (2) in Example 1;

[0044] In step (3), 3g thioacetamide, 4g sodium thiosulfate, 7g ferrous chloride, 0.6g maleic acid, 1.5g graphite powder, 0.5g sodium hydroxide, 0.015mg sodium dodecyl sulfate, 25mL titanium dioxide sol and 100mL deionized water are mixed evenly to obtain a composite plating solution.

[0045] The activated iron-carbon alloy material is placed in a composite plating solution, heated to 50°C in a water bath, and plating for 60 minutes. After plating, the material is removed, the surface is rinsed with ethanol to remove residual liquid, and then dried.

[0046] Step (4) is the same as step (4) in Example 1;

[0047] The self-lubricating sulfur-based film prepared in Example 2 has a thickness of 15.6 μm and contains 59.3% iron, 21.7% sulfur, 5.6% titanium, 7.4% oxygen, and 7% carbon by mass. It has a hardness of 369 HV, a coefficient of friction of 0.023, and a wear track depth of 0.011 mm.

[0048] Example 3

[0049] In step (1), the difference from Example 1 is that the mass of titanium dioxide (TiO2) powder is 14g;

[0050] Step (2) is the same as step (2) in Example 1;

[0051] In step (3), 5g thioacetamide, 5g sodium thiosulfate, 8g ferrous chloride, 1g glycine, 2g graphite powder, 0.6g sodium hydroxide, 0.02 mg sodium dodecyl sulfate, 50 mL titanium dioxide sol and 100 mL deionized water are mixed evenly to obtain a composite plating solution.

[0052] The activated iron-carbon alloy material is placed in a composite plating solution, heated to 50°C in a water bath, and plating for 60 minutes. After plating, the material is removed, the surface is rinsed with ethanol to remove residual liquid, and then dried.

[0053] Step (4) is the same as step (4) in Example 1;

[0054] The self-lubricating sulfur-based film obtained in Example 3 has a thickness of 16 μm and contains 61% iron, 25% sulfur, 5.6% titanium, 6% oxygen, and 2.4% carbon by mass. It has a hardness of 376 HV, a coefficient of friction of 0.021, and a wear track depth of 0.009 mm.

[0055] Example 4

[0056] In step (1), the difference from Example 1 is that the mass of titanium dioxide (TiO2) powder is 16g;

[0057] Step (2) is the same as steps (2)-(4) in Example 3;

[0058] The self-lubricating sulfur-based film obtained in Example 4 has a thickness of 17.5 μm and contains 62.3% iron, 23.9% sulfur, 5.4% titanium, 5.2% oxygen, and 3.2% carbon by mass. It has a hardness of 379 HV, a coefficient of friction of 0.020, and a wear track depth of 0.0087 mm.

[0059] Table 1 is a comparison table of the hardness and tribological properties of the self-lubricating sulfur-based films of the four embodiments with those of ordinary sulfur-based films.

[0060]

[0061] Compared with ordinary sulfur-based films, the self-lubricating sulfur-based films of Examples 1, 2, 3, and 4 showed increases in hardness of 30.1%, 37.1%, 39.7%, and 40.8%, respectively. The coefficients of friction were improved by 7.41%, 14.81%, 22.2%, and 25.9%, respectively.

[0062] The depth of wear marks decreased by 25%, 31.25%, 43.75%, and 45.6%.

[0063] Table 2 is a comparison table of the thickness and elemental content of the self-lubricating sulfur-based films of the four embodiments with those of ordinary sulfur-based films.

[0064]

[0065] Compared with ordinary sulfur-based films, the self-lubricating sulfur-based films of Examples 1, 2, 3, and 4 have increased thickness by 4.89%, 9.09%, 11.8%, and 22.3%, respectively. The iron content also increased to varying degrees.

[0066] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for preparing a wear-resistant and enhanced self-lubricating sulfur-based film, characterized in that... The operation steps are as follows: (1) Preparation of titanium dioxide sol Add 10g of titanium dioxide powder to 150mL of anhydrous ethanol, add nitric acid to adjust the pH to 3, heat in a water bath to 70℃, stir at 4500r / min for 40 min, and let stand for 72 h to obtain a light yellow titanium dioxide sol. (2) Preparation of activated iron-carbon alloy materials The surface of the iron-carbon alloy material was polished with sandpaper of 180 grit, 400 grit, and 2000 grit respectively to obtain an iron-carbon alloy material with a bright metallic luster, which is the part to be processed. Immerse and pickle in a 2% hydrochloric acid solution for 20-30 seconds; The material is activated in a 3%–5% hydrochloric acid solution for 10–15 seconds, rinsed with deionized water, vacuum dried, and then baked to obtain the activated iron-carbon alloy material. (3) Preparation of plated parts Mix 2–5 g of thioacetamide, 3–5 g of sodium thiosulfate, 5–8 g of ferrous chloride, 0.5–1 g of acid, 1–2 g of graphite powder, 0.2–0.6 g of sodium hydroxide, 0.01–0.02 mg of sodium dodecyl sulfate, 20–50 mL of titanium dioxide sol, and 100 mL of deionized water evenly to obtain a composite plating solution. The acid is one of maleic acid, citric acid, or glycine; The activated iron-carbon alloy material was placed in the composite plating solution, heated to 50°C in a water bath, and magnetic stirring was turned on. The plating time was 120 minutes to obtain the plated part. (4) Post-processing The plated parts are placed in a resistance furnace and heat-treated at 300°C for 1 hour under a nitrogen protective atmosphere; then placed in lubricating oil and cooled to room temperature. The resulting plated parts have a wear-resistant and enhanced self-lubricating sulfur-based film on their surface. The thickness of the self-lubricating sulfur-based film is 15~20μm, and the hardness is 350~500HV; The wear-resistant and enhanced self-lubricating sulfur-based film contains 40%~60% iron, 15%~30% sulfur, 5%~15% titanium, 10%~18% oxygen, and 3%~8% carbon by mass.

2. The preparation process of a wear-resistant and enhanced self-lubricating sulfur-based film according to claim 1, characterized in that: In step (1), the particle size of titanium dioxide powder is 400~450nm.

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