Preparation method of high-bearing and high-wear-resistance integrated functional layer on surface layer of shaft gear type workpiece
By employing a vacuum-modulated pulsed carbonitriding composite strengthening process and magnetron sputtering coating technology, combined with cryogenic and low-temperature tempering, a high-load-bearing and high-wear-resistant integrated functional layer was prepared. This solved the problems of insufficient hardness and bonding strength in traditional methods, enabling high-performance applications in bearings and gears.
Patent Information
- Application Number
- CN202511323456.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-12-19
AI Technical Summary
The surface hardness of carburized layers prepared by traditional carburizing methods has reached a bottleneck and is difficult to improve further. High-hardness films prepared by single coating methods have limited thickness and poor adhesion to the steel substrate, which makes them easy to peel off during the service of bearings and gears, thus limiting their industrial application.
A carbon-nitrogen composite strengthening process is adopted, which combines deep cryogenic and low-temperature tempering to form a carbon-nitrogen composite strengthening layer. Then, a high wear-resistant film is prepared on it by magnetron sputtering coating technology to form a high load-bearing and high wear-resistant integrated functional layer.
An effective hardened layer with a depth ≥3.5mm, a surface hardness ≥64HRC, a film hardness ≥10GPa, and a film-substrate bonding strength better than level 2 was prepared, resulting in a significant reduction in wear rate and meeting the requirements of heavy-duty gears and high-performance bearings in large equipment.
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Figure CN121161218A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of surface strengthening of mechanical parts, and particularly relates to a preparation method of a high-load-bearing and high-wear-resistance integrated functional layer on the surface layer of a shaft tooth type workpiece. BACKGROUND
[0002] Bearings and gears are the most important core parts in mechanical transmission devices, and directly determine the function, performance and reliability of main equipment. With the development of high-end equipment in the fields of engineering machinery and mining machinery towards large-scale and super power, bearings and gears are required to develop towards high hardness, large load, high wear resistance and long service life. The surface hardness of the carburized layer prepared by the traditional carburizing method has reached a bottleneck of 64HRC, and it is difficult to further improve. Hard thin film becomes a good candidate material for application in gearboxes and bearings due to its inherent high hardness, high wear resistance, low cost and other advantages. However, the high-hardness thin film prepared by a single plating method has a thickness of only microns, and there is a large performance difference between the thin film and the steel matrix, which is easy to produce a large residual stress and poor film-matrix adhesion, and is prone to peeling under the specific service conditions of bearings and gears, thereby limiting its industrial application.
[0003] Therefore, the application provides an integrated functional layer preparation method combining deep strengthening and surface plating, which forms a high-load-bearing and high-wear-resistance integrated functional layer (effective hardening layer depth is greater than or equal to 3.5mm, surface hardness is greater than or equal to 64HRC, and thin film hardness is greater than or equal to 10GPa) by a high-load-bearing carbon-nitrogen composite strengthening layer and a high-wear-resistance thin film, so as to meet the development trend and service requirements of large equipment heavy-duty gears and high-performance bearings. SUMMARY
[0004] Therefore, the application provides an integrated functional layer preparation method combining deep strengthening and surface plating, which forms a high-load-bearing and high-wear-resistance integrated functional layer (effective hardening layer depth is greater than or equal to 3.5mm, surface hardness is greater than or equal to 64HRC, and thin film hardness is greater than or equal to 10GPa) by a high-load-bearing carbon-nitrogen composite strengthening layer and a high-wear-resistance thin film, so as to meet the development trend and service requirements of large equipment heavy-duty gears and high-performance bearings. A preparation method of a high-load-bearing and wear-resistant integrated functional layer on the surface layer of a shaft tooth type part, comprising the following stages: a vacuum variable pulse carbon-nitrogen composite strengthening process, deep cooling, low-temperature tempering and magnetron sputtering plating. The carbon-nitrogen composite strengthening layer is formed on the surface of the shaft tooth type part as a bearing layer through the vacuum variable pulse carbon-nitrogen composite strengthening process. Deep cooling treatment promotes martensite transformation and improves surface hardness. Low-temperature tempering stabilizes the performance of the carbon-nitrogen composite strengthening layer. Magnetron sputtering plating forms a high-wear-resistance thin film, and the bearing layer and the thin film together form an integrated functional layer.
[0005] Further, the vacuum variable pulse carbon-nitrogen composite strengthening process comprises a segmented heating process, a variable pulse carburizing process, a variable pulse carbon-nitrogen double infiltration process and a segmented oil quenching or gas quenching process.
[0006] Further, the segmented temperature rising process comprises one-stage preheating and two-stage preheating; the preheating stage is determined according to the carburizing temperature of the workpiece; the variable-pulse carburizing process and the variable-pulse carbon-nitrogen double-permeation process adopt a variable-pulse mode, each pulse comprising a gas filling process, a pressure maintaining process and a gas extraction process, the pressure maintaining time gradually shortens and the gas extraction time gradually lengthens as the process proceeds.
[0007] Further, the temperature of the variable-pulse carburizing process is higher than that of the variable-pulse carbon-nitrogen double-permeation process, the ratio of the carburizing pulse to the nitriding pulse in the carbon-nitrogen double-permeation process is less than or equal to 1, and the ratio of the carburizing pressure to the nitriding pressure is greater than or equal to 2.
[0008] Further, the segmented oil quenching process is carried out under nitrogen protection to prevent surface denitrogenation.
[0009] Further, the cooling medium used in the gas quenching process is nitrogen, argon, hydrogen or a mixture of two gases, and the cooling rate of the gas quenching process is higher than the critical cooling rate of carbon / nitrogen-containing martensite transformation.
[0010] Further, the cooling rate of the deep cooling process is less than or equal to 10°C / s, and the deep cooling temperature is lower than the end temperature of martensite transformation.
[0011] Further, the deposition temperature of the magnetron sputtering film plating stage is lower than the low-temperature tempering temperature of the workpiece, to prevent the hardness of the carbon-nitrogen composite strengthening layer from decreasing due to tempering; the plating film is diamond-like carbon (DLC), TiC or TiN.
[0012] Further, the surface hardness of the integrated functional layer is greater than or equal to 64 HRC, the effective hardening layer depth is greater than or equal to 3.5 mm, and the film hardness is greater than or equal to 10 GPa.
[0013] Further, the method is suitable for bearing steel or gear steel materials, and the shaft gear type parts include gears, bearings or combinations thereof.
[0014] The present application prepares a certain depth of carbon-nitrogen composite strengthening layer as a bearing layer on shaft gear type parts through a vacuum variable-pulse carbon-nitrogen composite strengthening process, a deep cooling process promotes the transformation of martensite, further improves the surface hardness, low-temperature tempering improves the stability of the carbon-nitrogen composite strengthening layer, and then a magnetron sputtering film plating technology is used to prepare a high wear-resistant film such as diamond-like carbon (DLC), TiC and TiN, etc., and the two together form a high bearing and high wear-resistant integrated functional layer (film hardness is greater than or equal to 10 GPa, surface hardness is greater than or equal to 64 HRC, and effective hardening layer depth is greater than or equal to 3.5 mm), and the wear rate is greatly reduced.
[0015] The present application has the following advantages: 1. The present application successfully prepares a high load and high wear resistance integrated functional layer on ordinary bearing and gear steel by combining vacuum carbon-nitrogen pulse composite strengthening technology and magnetron sputtering coating technology, the high load carbon-nitrogen composite strengthening layer and the high wear resistance thin film form the high load and high wear resistance integrated functional layer together, the effective hardening depth is greater than or equal to 3.5mm, the surface hardness is greater than or equal to 64HRC, the thin film hardness is greater than or equal to 10GPa, the film-substrate adhesion is better than 2 levels, the wear rate is greatly reduced, the limitation of single carburizing and coating technology is broken, and the development trend and service requirements of large equipment heavy load gears and high performance bearings are met.
[0016] 2. The high load and high wear resistance integrated functional layer preparation method for shaft gear workpiece surface layers provided by the present application has high integration degree, the carbon-nitrogen composite process can be completed on one vacuum equipment, the operation is simple, the production cycle is shortened, the application range is wide, and therefore the present application has important engineering application value. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 The high load and high wear resistance integrated functional layer preparation process curve in the present application is for Example 1. Figure 2 The variation diagram of the type and pressure of gas in the vacuum variable pulse carbon-nitrogen double infiltration and segmented oil quenching process in the present application is for Example 1. Figure 3 The cross-section metallographic photo of the carbon-nitrogen composite strengthening layer in the present application is for Example 1. Figure 4 The scanning photo of the surface of the high load and high wear resistance integrated functional layer in the present application is for Example 1. Figure 5 The microhardness distribution of the high load and high wear resistance integrated functional layer in the present application is for Example 1. Figure 6 The nanoindentation test curve of the surface of the high load and high wear resistance integrated functional layer in the present application is for Example 1. Figure 7 The adhesion test of the high load and high wear resistance integrated functional layer in the present application is for Example 1. Figure 8 The wear rate of the high load and high wear resistance integrated functional layer in the present application is for Example 1. DETAILED DESCRIPTION
[0018] In order to make the purpose, advantages and characteristics of the present application more obvious, the following specific embodiments further illustrate the present application in detail.
[0019] Detailed implementation one: the preparation method of the high load and high wear resistance integrated functional layer of the surface layer of the shaft tooth type workpiece, including four stages of vacuum variable pulse carbon and nitrogen composite strengthening process, cryogenic treatment, low temperature tempering and magnetron sputtering film coating, a certain depth of carbon and nitrogen composite strengthened layer is prepared on the shaft tooth type part as a bearing layer through the vacuum variable pulse carbon and nitrogen composite strengthening process, the cryogenic treatment process promotes the transformation of martensite, and further improves the surface hardness; the low temperature tempering improves the stability of the carbon and nitrogen composite strengthened layer, and prevents the performance of the bearing layer from changing obviously during the film coating process; finally, a high wear resistance film such as diamond-like carbon DLC, TiC and TiN is prepared through the magnetron sputtering film coating technology, and the two form a high load and high wear resistance integrated functional layer. The vacuum variable pulse carbon and nitrogen composite strengthening process specifically includes a segmented heating process, a variable pulse carburizing process, a variable pulse carbon and nitrogen double infiltration, and a segmented oil quenching process. The segmented heating process is divided into one-stage preheating and two-stage preheating, and the segmentation depends on the carburizing temperature of the workpiece; the vacuum carburizing and vacuum carbon and nitrogen double infiltration processes both adopt a variable pulse mode, each pulse includes a gas charging, pressure maintaining and gas extraction process, the pressure maintaining time gradually decreases and the gas extraction time gradually increases as the carburizing process proceeds.
[0020] The vacuum carburizing temperature of the vacuum variable pulse carbon and nitrogen composite strengthening process is higher than the temperature of the carbon and nitrogen double infiltration, the ratio of the carburizing pulse to the nitriding pulse in the carbon and nitrogen double infiltration process is ≤1, and the ratio of the carburizing pressure to the nitriding pressure is ≥2. The segmented oil quenching process needs to be carried out in nitrogen protection to prevent surface denitrogenation. The cooling speed of the cryogenic treatment process is ≤10°C / s, and the temperature of the cryogenic treatment needs to be lower than the martensite transformation end temperature. The deposition temperature of the magnetron sputtering film coating stage is lower than the temperature of the low temperature tempering of the workpiece, so as to prevent the hardness of the carbon and nitrogen composite strengthened layer from decreasing due to tempering, and the high wear resistance film prepared is diamond-like carbon DLC, TiC and TiN.
[0021] Detailed implementation two: the difference between the present embodiment and detailed implementation one is that the cooling process of the vacuum variable pulse carbon and nitrogen composite strengthening process adopts gas quenching, and the cooling medium can be nitrogen, argon, hydrogen and a mixture of two gases. The cooling speed of the gas quenching process is higher than the critical cooling speed of the carbon / nitrogen-containing martensite transformation. Example one: Material: 20Cr2Ni4A bearing.
[0022] Technical requirements: surface hardness ≥64 HRC; hardened layer depth (CHD) ≥3.5 mm.
[0023] A preparation method of a high load and wear resistance and friction reduction integrated functional layer of the surface layer of a shaft tooth type part, which is carried out according to the following steps: It includes four stages: vacuum pulsed carbonitriding strengthening process, cryogenic treatment, low-temperature tempering, and magnetron sputtering coating, such as... Figure 1 As shown, a certain depth of a load-bearing layer is prepared on shaft gear parts by vacuum variable pulse carbonitriding composite strengthening process. The deep cryogenic process promotes the transformation of martensite and further improves the surface hardness. Low temperature tempering improves the stability of carbonitriding composite strengthening layer and prevents significant changes in the performance of load-bearing layer during the coating process. Finally, a high wear-resistant thin film diamond-like carbon (DLC) is prepared by magnetron sputtering coating technology. The two together form a high load-bearing and high wear-resistant integrated functional layer. The vacuum variable pulse carbonitriding composite strengthening process specifically includes a segmented heating process, a variable pulse carburizing process, a variable pulse carbonitriding process, and a segmented oil quenching process. The segmented heating process is divided into one preheating stage and two preheating stages, and the segmentation depends on the carburizing temperature of the workpiece. The vacuum carburizing and vacuum carbonitriding processes both adopt a variable pulse method. Each pulse includes gas filling, pressure holding, and gas extraction processes. As the carburizing process proceeds, the pressure holding time gradually decreases and the gas extraction time gradually increases.
[0024] The vacuum carburizing temperature in the vacuum variable pulse carbonitriding composite strengthening process is higher than that in the carbonitriding dual process. The ratio of carburizing pulses to nitriding pulses in the carbonitriding dual process is 1, and the ratio of carburizing pressure to nitriding pressure is 2. For example... Figure 2 As shown; The segmented oil quenching process needs to be carried out under nitrogen protection to prevent surface denitrification, such as Figure 2 As shown; The cryogenic process has a cooling rate of 3.5°C / s, and the cryogenic temperature of -80°C needs to be lower than the martensitic transformation end temperature. The deposition temperature during the magnetron sputtering coating stage is ≤150°C, which is lower than the workpiece's low-temperature tempering temperature of 180°C. This prevents the carbon-nitrogen composite reinforcement layer from tempering and reducing its hardness. The resulting high-wear-resistant film is diamond-like carbon (DLC).
[0025] Figure 3 The metallographic structure of the carbon-nitrogen composite reinforced layer obtained after low-temperature tempering shows that the carbide level is better than level 2.
[0026] Figure 4 The image shows a scanning image of the surface of the high load-bearing and high wear-resistant integrated functional layer. It can be seen that a DLC thin film was deposited on the surface after magnetron sputtering. Figure 5 The microhardness distribution of the prepared high load-bearing and high wear-resistant integrated functional layer is shown. It can be seen that the surface hardness of the integrated functional layer reaches 850 HV (~66 HRC) and the effective hardened layer (hardness ≥ 550 HV) depth is ≥ 3.5 mm. Figure 6According to the nano-indentation test curve of the surface of the high wear-resistant integrated functional layer, the hardness of the thin film can be calculated as 19.88 GPa, which meets the requirement of ≥10 GPa; Figure 7 The adhesion test of the high wear-resistant integrated functional layer shows that only a small amount of cracks occur around the indentation without peeling, which indicates that the film-base adhesion is better than level 2. Figure 8 To compare the wear rates of the high wear-resistant integrated functional layer and single carburizing and carbonitriding, the wear rate of the functional layer is greatly reduced by an order of magnitude compared with single carburizing.
[0027] The above examples have described the technical solutions of the present application in detail. Apparently, the present application is not limited to the described examples. Based on the examples in the present application, those skilled in the art can make various changes, but any change equivalent or similar to the present application belongs to the protection scope of the present application.
[0028] The contents not described in detail in the specification belong to the prior art known to those skilled in the art.
Claims
1. A method for preparing a surface layer of a high bearing wear-resistant and friction-reducing integrated functional layer of a pin gear part, characterized in that, The method comprises the following stages: vacuum variable pulse carbon-nitrogen composite strengthening process, deep cooling, low-temperature tempering, magnetron sputtering film coating. The vacuum variable pulse carbon-nitrogen composite strengthening process is used to form a carbon-nitrogen composite strengthening layer as a bearing layer on the surface of the shaft-tooth part. The deep cooling process promotes martensite transformation and improves the surface hardness. The low-temperature tempering process stabilizes the performance of the carbon-nitrogen composite strengthening layer. The magnetron sputtering film coating forms a high-wear-resistant film, which, together with the bearing layer, forms an integrated functional layer.
2. The method of claim 1, wherein, The vacuum variable pulse carbon-nitrogen composite strengthening process comprises a segmented heating process, a variable pulse carburizing process, a variable pulse carbon-nitrogen double-permeation process, and a segmented oil quenching or gas quenching process.
3. The method of claim 2, wherein, The segmented heating process comprises one-stage preheating and two-stage preheating; the preheating stages are determined according to the carburizing temperature of the workpiece; the variable pulse carburizing process and the variable pulse carbon-nitrogen double-permeation process adopt a variable pulse mode, each pulse comprising a gas charging process, a pressure maintaining process and a gas extraction process, the pressure maintaining time gradually shortens and the gas extraction time gradually lengthens as the process proceeds.
4. The method of claim 2, wherein, The temperature of the variable pulse carburizing process is higher than that of the variable pulse carbon-nitrogen double-permeation process, the ratio of the carburizing pulse to the nitriding pulse in the carbon-nitrogen double-permeation process is ≤1, and the ratio of the carburizing pressure to the nitriding pressure is ≥2.
5. The method of claim 2, wherein, The segmented oil quenching process is carried out under nitrogen protection to prevent surface denitrogenation.
6. The method of claim 2, wherein, The cooling medium used in the gas quenching process is nitrogen, argon, hydrogen or a mixture of two gases; the cooling rate of the gas quenching process is higher than the critical cooling rate of the carbon / nitrogen-containing martensite transformation.
7. The method of claim 1, wherein, The cooling rate of the deep cooling process is ≤10°C / s, and the deep cooling temperature is lower than the end temperature of the martensite transformation.
8. The method of claim 1, wherein, The deposition temperature of the magnetron sputtering film coating stage is lower than the low-temperature tempering temperature of the workpiece, so as to prevent the carbon-nitrogen composite strengthening layer from being tempered and the hardness from being reduced; the coated film is diamond-like carbon (DLC), TiC or TiN.
9. The method of claim 1, wherein, The surface hardness of the integrated functional layer is ≥64 HRC, the effective hardening layer depth is ≥3.5 mm, and the film hardness is ≥10 GPa.
10. The method of claim 1, wherein, The method is suitable for bearing steel or gear steel materials, and the shaft-tooth part comprises a gear, a bearing or a combination thereof.