Low-temperature and high-efficiency super-thick sulfurizing treatment method for workpiece surface

Abstract

The application discloses a kind of workpiece surface low-temperature high-efficiency super-thick sulphurizing treatment methods, comprising the following steps: 1) the workpiece to be treated is cleaned to remove the oil dirt and impurities on the surface of workpiece;2) the cleaned workpiece is placed in a vacuum furnace, vacuum is extracted;3) after mixing rare earth compound containing lanthanum and cerium and sulfide, heating evaporation is carried out, to obtain rare earth ions and sulfur ions;4) under low temperature conditions, rare earth ions and sulfur ions are introduced into the vacuum furnace, under the action of electric field, high-energy microparticles are formed, impact and penetrate into the surface of workpiece. By the treatment method of the application, the penetration speed can be increased by 20%-30%, the thickness of sulfurized layer is increased from several tens of microns to 0.5mm-1.5mm, the durability is increased by 2-3 times;At the same time, the sulphurizing process cycle of workpiece can be significantly shortened by more than 10%.

Description

Technical Field

[0001] The invention belongs to the technical field of workpiece surface treatment, and in particular relates to a low-temperature, high-efficiency, ultra-thick sulfurization treatment method for a workpiece surface. Background Art

[0002] With the advancement of science and technology and the demands of production development, materials surface engineering technology, as a new, comprehensive discipline, has rapidly developed both domestically and internationally. Especially in today's global circular economy and low-carbon development, materials surface engineering technology has found widespread application in fields such as machinery, automotive, materials, and metallurgy. According to incomplete statistics, friction accounts for one-third to one-half of the world's energy consumption, and 80% of mechanical part failures are caused by wear. Practice has proven that the application of materials surface engineering technology can effectively improve material surface properties, extend component life, conserve resources and energy, and reduce environmental pollution, resulting in a high input-output ratio.

[0003] To reduce the coefficient of friction on a workpiece surface and improve wear and seizure resistance, those skilled in the art typically perform a sulfurization treatment on the workpiece surface, forming a FeS sulfurized layer. Because FeS has a close-packed hexagonal lattice structure, it can slide along its (0001) basal plane. Furthermore, the sulfide is loose and porous, making it easy to store oil and facilitating good lubrication. The sulfurized layer also improves the workpiece surface condition, preventing direct contact between the friction pair surfaces that can cause adhesion. Therefore, sulfurization can reduce friction and wear, and improve seizure resistance and fatigue performance. Chinese patent CN1528943A discloses a low-temperature vacuum sulfurization method. This method involves placing the workpiece on the cathode plate of a low-vacuum container, connecting the vacuum container housing to the anode plate, and adding a small amount of sulfur. A direct current voltage is applied across the anode and cathode. When the voltage reaches a certain value, the sulfur is directly ionized into sulfur ions under the action of the electric field. The resulting positive ions, generated by gas ionization, are accelerated by the sharp cathode voltage drop near the cathode as they move toward the cathode. These high-speed ions bombard the metal surface and penetrate the metal matrix, forming a sulfurized layer. To maintain the roughness, precision, hardness, and metallographic structure of the workpiece being treated, the maximum temperature within the patented sulfurizing vessel is 250°C. However, in practice, it has been found that sulfurizing temperatures below 250°C affect the sulfurization rate and the thickness of the sulfurized layer, leading to premature wear of the sulfurized layer during operation and poor durability. For larger parts, a slower sulfurization rate can affect production efficiency and increase production costs.

[0004] In summary, the existing sulfurization treatment method for workpiece surface has the defects of slow infiltration rate, long infiltration time, thin infiltration layer thickness and low production efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a low-temperature, high-efficiency, ultra-thick sulfurization treatment method for workpiece surfaces. This treatment method uses rare earth catalysis, taking advantage of the highly active nature of rare earth elements to microalloy the workpiece surface, increase the density of surface grain boundaries and internal crystal defects, accelerate interfacial reactions, promote the diffusion of sulfur along grain boundaries, and increase the surface sulfurization rate and thickness of the sulfurized layer. This improves the friction reduction, wear resistance, anti-seizure properties, and durability of the workpiece surface, thereby adapting to harsh working conditions such as rolling-sliding or sliding. Through the treatment method of the present invention, the sulfurization rate can be increased by 20%-30%, the sulfurized layer thickness can be increased from tens of microns to 0.5mm-1.5mm, and the durability can be increased by 2-3 times. At the same time, the sulfurization process cycle of the workpiece can be significantly shortened by more than 10%, reducing production costs and improving production efficiency.

[0006] In order to solve the above technical problems, the invention adopts the following technical solutions :

[0007] A method for low-temperature, high-efficiency, ultra-thick sulfurizing treatment of a workpiece surface comprises the following steps:

[0008] 1) Clean the workpiece to be processed to remove oil and impurities on the surface of the workpiece;

[0009] 2) Place the cleaned workpiece in a vacuum furnace and evacuate the vacuum;

[0010] 3) mixing a rare earth compound containing lanthanum and cerium with a sulfide and heating and evaporating the mixture to obtain rare earth ions and sulfide ions;

[0011] 4) Under low temperature conditions, rare earth ions and sulfur ions are introduced into a vacuum furnace. Under the action of the electric field, high-energy particles are formed, which collide with and penetrate into the surface of the workpiece.

[0012] As an embodiment, in step 1), the cleaning is ultrasonic cleaning for 20-30 minutes.

[0013] As an embodiment, in step 2), the vacuum is evacuated to a pressure of 40-70 Pa.

[0014] As an embodiment, in step 3), the rare earth compound contains 17-30 wt% lanthanum and 45-50 wt% cerium.

[0015] As an embodiment, in step 3), the sulfide is one of FeS, La2S3, and Ce2S3. However, since rare earths have a relatively low affinity for sulfur, the sulfide is mainly FeS.

[0016] As an embodiment, in step 3), the weight ratio of the rare earth compound to the sulfide is 1:1-3.

[0017] As an embodiment, in step 3), the rare earth compound is heated and evaporated at a temperature of 800-1000°C;

[0018] As an embodiment, in step 4), the low temperature condition refers to a temperature of 80-200°C;

[0019] As an embodiment, in step 4), the voltage of the electric field is 450-1000V.

[0020] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0021] Unless otherwise specified, all raw materials in the present invention can be purchased commercially, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0022] Compared with the prior art, the present invention has the following beneficial effects :

[0023] 1) In the treatment method of the present invention, rare earth is highly active and can reduce iron oxide on the surface of the workpiece to generate new iron, thereby cleaning the surface;

[0024] 2) In the treatment method of the present invention, rare earth metals microalloy the workpiece surface, increase the density of surface grain boundaries and internal crystal defects, accelerate the activity of interfacial reactions, promote the diffusion of sulfur along the grain boundaries, and increase the infiltration rate and thickness of the infiltration layer on the workpiece surface;

[0025] 3) In the treatment method of the present invention, in order to avoid problems such as reduced surface hardness of parts and dimensional deformation of parts, a method of infiltrating (rare earth + sulfur) ions at a temperature below 200°C is adopted;

[0026] 4) In the treatment method of the present invention, since rare earth catalyzes the infiltration and increases the interfacial activity, the temperature control range is relatively large, and the two ions can be infiltrated in the range of 80°C to 200°C;

[0027] 5) In the treatment method of the present invention, the sulfurization rate can be increased by 20%-30%, and the thickness of the sulfurized layer is increased from tens of microns to 0.5mm-1.5mm;

[0028] 6) The treatment method of the present invention can significantly shorten the sulfurization process cycle of the workpiece by 10%-20%, reduce production costs and improve production efficiency.

[0029] 7) In the treatment method of the present invention, the solid sulfurizing agent is first evaporated and then ionized, and then introduced into the furnace after the ions are formed, thereby avoiding problems such as corrosion, toxicity and explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1Schematic diagram of microstructural changes after rare earth ions penetrate into the workpiece surface during the sulfurizing process of the present invention;

[0031] Figure 2 Schematic diagram of ion diffusion in conventional sulfurizing process;

[0032] Figure 3 Schematic diagram of ion diffusion in the sulfurizing process of the present invention. DETAILED DESCRIPTION

[0033] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0034] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0035] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0037] See also Figure 1-Figure 3 As shown, as one aspect of the present invention, a method for low-temperature, high-efficiency, ultra-thick sulfurizing treatment of a workpiece surface comprises the following steps:

[0038] 1) Clean the workpiece to be processed to remove oil and impurities on the surface of the workpiece;

[0039] 2) Place the cleaned workpiece in a vacuum furnace and evacuate the vacuum;

[0040] 3) mixing a rare earth compound containing lanthanum and cerium with a sulfide and heating and evaporating the mixture to obtain rare earth ions and sulfide ions;

[0041] 4) Under low temperature conditions, rare earth ions and sulfur ions are introduced into a vacuum furnace. Under the action of the electric field, high-energy particles are formed, which collide with and penetrate into the surface of the workpiece.

[0042] In certain embodiments, in step 1), the cleaning is ultrasonic cleaning for 20-30 minutes.

[0043] In certain embodiments, in step 2), the vacuum is evacuated to a pressure of 40-70 Pa.

[0044] In certain embodiments, in step 3), the rare earth compound contains 17-30 wt% lanthanum and 45-50 wt% cerium.

[0045] In some embodiments, in step 3), the sulfide is one of FeS, La2S3, and Ce2S3. However, since rare earths have relatively low affinity for sulfur, the sulfide is mainly FeS.

[0046] In certain embodiments, in step 3), the weight ratio of the rare earth compound to the sulfide is 1:1-3.

[0047] In certain embodiments, in step 3), the temperature of the heating evaporation is 800-1000°C.

[0048] In certain embodiments, in step 4), the low temperature condition refers to a temperature of 80-200°C. The higher the temperature, the higher the penetration rate of the elements, the thicker the penetration layer, and thus the improved surface performance of the workpiece; however, the problem caused by high temperature is that the surface hardness is reduced and the dimensional accuracy is deteriorated, which is very unfavorable for some parts, such as gears and bearings. Therefore, low-temperature sulfurization is generally adopted in the industry, but low-temperature sulfurization has the problems of low penetration rate and thin penetration layer. The present invention can also have a higher penetration rate and a thicker sulfurized layer under the condition of low-temperature sulfurization.

[0049] In some embodiments, in step 4), the voltage of the electric field is 450-1000V.

[0050] Example 1

[0051] A method for low-temperature, high-efficiency, ultra-thick sulfurizing treatment of a workpiece surface comprises the following steps:

[0052] 1) Ultrasonic cleaning is performed on the workpiece to be processed to remove oil and impurities on the surface of the workpiece;

[0053] 2) Place the cleaned workpiece into a vacuum furnace and evacuate to 45Pa;

[0054] 3) mixing a rare earth compound containing lanthanum and cerium (17 wt% lanthanum + 45 wt% cerium) with a sulfide in a ratio of 1:1 and heating the mixture to 850° C. to evaporate the mixture, thereby obtaining rare earth ions and sulfide ions;

[0055] 4) When the temperature inside the furnace reaches 90°C, rare earth and sulfur ions are introduced into the vacuum furnace. Under the action of an electric field of 500V, high-energy particles are formed to collide with and penetrate into the surface of the workpiece.

[0056] According to tests, the sulfurization treatment process of this embodiment increases the sulfurization rate by 20%, and the thickness of the sulfurized layer reaches 0.5 mm, which can significantly shorten the sulfurization process cycle of the workpiece by 10%.

[0057] Example 2

[0058] A method for low-temperature, high-efficiency, ultra-thick sulfurizing treatment of a workpiece surface comprises the following steps:

[0059] 1) Ultrasonic cleaning is performed on the workpiece to be processed to remove oil and impurities on the surface of the workpiece;

[0060] 2) Place the cleaned workpiece into a vacuum furnace and evacuate to 55Pa;

[0061] 3) mixing a rare earth compound containing lanthanum and cerium (25 wt% lanthanum + 47 wt% cerium) with sulfide in a ratio of 2:1 and heating to 950° C. to evaporate and obtain rare earth ions and sulfide ions;

[0062] 4) When the temperature inside the furnace reaches 150°C, rare earth and sulfur ions are introduced into the vacuum furnace. Under the action of an electric field of 750V, high-energy particles are formed that collide with and penetrate into the surface of the workpiece.

[0063] According to tests, the sulfurization treatment process of this embodiment increases the sulfurization rate by 25%, and the thickness of the sulfurized layer reaches 1.0 mm, which can significantly shorten the sulfurization process cycle of the workpiece by 12%.

[0064] Example 3

[0065] A method for low-temperature, high-efficiency, ultra-thick sulfurizing treatment of a workpiece surface comprises the following steps:

[0066] 1) Ultrasonic cleaning is performed on the workpiece to be processed to remove oil and impurities on the surface of the workpiece;

[0067] 2) Place the cleaned workpiece into a vacuum furnace and evacuate to 60Pa;

[0068] 3) mixing a rare earth compound containing lanthanum and cerium (30 wt% lanthanum + 50 wt% cerium) with a sulfide in a ratio of 3:1, heating the mixture to 950° C. and evaporating the mixture to obtain rare earth ions and sulfide ions;

[0069] 4) When the temperature in the furnace reaches 200°C, rare earth and sulfur ions are introduced into the vacuum furnace. Under the action of an electric field of 950V, high-energy particles are formed that collide with and penetrate into the surface of the workpiece.

[0070] According to tests, the sulfurization treatment process of this embodiment increases the sulfurization rate by 30%, and the thickness of the sulfurized layer reaches 1.5 mm, which can significantly shorten the sulfurization process cycle of the workpiece by 15%.

[0071] Comparative Example 1

[0072] Example 3 was repeated except that: in step 3) a rare earth compound containing lanthanum and cerium (10 wt% lanthanum + 35 wt% cerium) was mixed with sulfide and heated and evaporated to obtain rare earth ions and sulfide ions.

[0073] According to the test, the sulfurization treatment process of this embodiment only increases the sulfurization rate by 1%, and the thickness of the sulfurized layer is 0.10 mm, which fails to effectively shorten the sulfurization process cycle of the workpiece.

[0074] Comparative Example 2

[0075] Example 3 was repeated except that: in step 3) a rare earth compound containing lanthanum and cerium (5 wt% lanthanum + 25 wt% cerium) was mixed with sulfide and heated and evaporated to obtain rare earth ions and sulfide ions.

[0076] After testing, it was found that the sulfurization rate of the sulfurization treatment process in this embodiment could not be improved, the thickness of the sulfurized layer was 0.08 mm, and the sulfurization process cycle of the workpiece could not be shortened.

[0077] Comparative Example 3

[0078] Example 3 was repeated except that: in step 3) a rare earth compound containing lanthanum and cerium (0 wt% lanthanum + 10 wt% cerium) was mixed with sulfide and heated and evaporated to obtain rare earth ions and sulfide ions.

[0079] After testing, it was found that the sulfurization rate of the sulfurization treatment process in this embodiment could not be improved, the thickness of the sulfurized layer was 0.01 mm, and the sulfurization process cycle of the workpiece could not be shortened.

[0080] Comparative Example 4

[0081] Example 3 was repeated, with the only difference being that in step 4) when the furnace temperature reached 300°C, rare earth and sulfur ions were introduced into the vacuum furnace. Under the action of an electric field of 1200V, high-energy particles were formed that collided with and penetrated the workpiece surface.

[0082] After testing, the sulfurization treatment process in this embodiment increases the permeation rate by 35%, and the thickness of the sulfurized layer reaches 0.20 mm, which can significantly shorten the sulfurization process cycle of the workpiece by 20%. However, the surface hardness of the workpiece decreases, the surface accuracy deteriorates, and compounds such as Fe2S3, La2O3, and Ce2O3, which are not conducive to performance, are formed on the surface.

[0083] The present invention is not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be considered as equivalent replacement methods and shall be included in the scope of protection of the present invention.

[0084] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications based on the above description are possible. It is not possible to enumerate all embodiments here. Any obvious variations or modifications arising from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. A low-temperature, high-efficiency, ultra-thick sulfurizing treatment method for a workpiece surface, characterized in that: The steps include: 1) Clean the workpiece to be processed to remove oil and impurities on the surface of the workpiece; 2) Place the cleaned workpiece in a vacuum furnace and evacuate the vacuum; 3) Mixing a rare earth compound containing lanthanum and cerium with a sulfide and heating and evaporating the mixture to obtain rare earth ions and sulfide ions; 4) Under low temperature conditions, rare earth ions and sulfur ions are introduced into a vacuum furnace. Under the action of the electric field, high-energy particles are formed, which collide with and penetrate into the surface of the workpiece; the thickness of the formed sulfurized layer is 0.5mm to 1.5mm; In step 3), the rare earth compound contains 17-30 wt% lanthanum and 45-50 wt% cerium; In step 3), the sulfide is one of FeS, La2S3, and Ce2S3; In step 4), the low temperature condition refers to a temperature of 80-200°C.

2. The method for treating the workpiece surface with low temperature, high efficiency and ultra-thick sulfurization according to claim 1, characterized in that: In step 1), the cleaning is ultrasonic cleaning for 20-30 minutes.

3. The method for treating the surface of a workpiece at low temperature, high efficiency and ultra-thick sulfurizing according to claim 1, characterized in that: In step 2), the vacuum is evacuated to a pressure of 40-70 Pa.

4. The method for treating a workpiece surface with low temperature, high efficiency and ultra-thick sulfurization according to claim 1, characterized in that: In step 3), the weight ratio of the rare earth compound to the sulfide is 1:1-3.

5. The method for treating the workpiece surface with low temperature, high efficiency and ultra-thick sulfurization according to claim 1, characterized in that: In step 3), the heating and evaporation temperature is 800-1000°C.

6. The method for treating a workpiece surface with low temperature, high efficiency and ultra-thick sulfurization according to claim 1, characterized in that: In step 4), the voltage of the electric field is 450-1000V.

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