A bearing steel ion implantation surface treatment method

Abstract

The present invention discloses a method for ion implantation surface treatment of bearing steel. The method uses SRIM software to simulate the ion implantation of multiple metal elements, extracting the ratio of vacancies to implanted ions generated by each metal element in the bearing steel or bearing component to be surface treated. The metal element with the highest vacancy-to-implanted ion ratio is selected as the optimal implantation metal element for ion implantation, and a gas element is then implanted. The method can significantly improve the friction and wear resistance of the bearing steel or bearing component under the special operating conditions of starved oil lubrication.

Description

Technical Field

[0001] The invention relates to a bearing steel ion implantation surface treatment method, belonging to the field of ion beam surface strengthening of metal materials. Background Art

[0002] Bearings are crucial components of aircraft engines, operating under extreme conditions such as high temperatures, high speeds, and heavy loads. Bearings used in helicopter engines or gear transmissions also face the unique challenge of operating under short-term lubrication starvation. Bearing steel must possess not only excellent strength, stiffness, toughness, and fatigue resistance, but also excellent resistance to friction and wear. Improving the fatigue and friction and wear resistance of bearing steel through surface treatment is an effective way to enhance the service performance of aircraft bearings.

[0003] Ion implantation surface treatment is currently widely used for surface strengthening of bearing steel. For example, Chinese patent ZL201610922041.5 discloses a method for treating cronidur30 bearing steel, strengthening cronidur30 bearing steel, and bearings. This method uses alternating injection of metal ions and gas ions to strengthen cronidur30 bearing steel. This method addresses the problem of reduced material properties caused by nitrogen loss from the cronidur30 bearing steel surface, while also improving the anti-wear and friction-reducing properties of cronidur30 bearing steel. However, existing ion implantation surface modification methods still struggle to meet the friction and wear resistance requirements of bearing steel under the specialized operating conditions of oil-starved lubrication, and new ion implantation methods for bearing steel surface strengthening are urgently needed. Summary of the Invention

[0004] The present invention provides a method for surface treatment of bearing steel by ion implantation. This method uses SRIM software to simulate the ion implantation of multiple metal elements, extracting the ratio of vacancies to implanted ions generated by each metal element in the bearing steel or bearing component to be surface treated. The metal element with the highest vacancy-to-implanted ion ratio is then selected as the optimal implanted metal element for ion implantation. Furthermore, a gas element is implanted, significantly improving the friction and wear resistance of the bearing steel or bearing component under the special operating conditions of starved oil lubrication.

[0005] The technical solutions for achieving the purpose of the present invention are as follows:

[0006] A bearing steel ion implantation surface treatment method comprises the following steps:

[0007] (1) In the SRIM software, set the main component of the substrate layer to be consistent with the main component of the bearing steel or bearing element to be surface treated, and set the metal element injection voltage or energy and the number of injections;

[0008] (2) Start the SRIM software to simulate the ion implantation of the metal element to be selected, and extract the ratio of the number of vacancies and the number of implanted ions generated by the metal element to be selected in the bearing steel or bearing component to be surface treated in the output result;

[0009] (3) Replace other metal elements to be selected and repeat steps (1) to (2) until the vacancy-injection ion number ratios of all metal elements to be selected are obtained;

[0010] (4) Selecting a metal element with a high vacancy-to-injection ratio as the optimal implantation metal element;

[0011] (5) Perform ion beam or plasma cleaning on the bearing steel or bearing components to be surface treated in a vacuum chamber before implantation;

[0012] (6) According to the metal element injection voltage or energy set in step (1), the best metal element is ion-injected into the surface of the cleaned bearing steel or bearing component, and then the gas element is injected; or the gas element is first injected into the surface of the cleaned bearing steel or bearing component, and then according to the metal element injection voltage or energy set in step (1), the best metal element is ion-injected into the surface of the cleaned bearing steel or bearing component.

[0013] Furthermore, in step (1), the metal elements to be selected are metal elements commonly used in bearing steel metal element ion implantation technology, including but not limited to titanium, chromium, nickel, zirconium, niobium, molybdenum, tantalum, silver, tungsten, etc.

[0014] Furthermore, in step (1) or (6), the injection voltage is a voltage conventionally used in bearing steel metal element ion injection technology, such as 20 kV to 70 kV.

[0015] Furthermore, in step (1), the number of injections is greater than 1000. The higher the number of injections, the higher the accuracy, but the longer the time required. Preferably, the number is between 1000 and 10000. In the specific embodiment of the present invention, 10000 is used as an example.

[0016] Furthermore, in step (5), the ion beam cleaning conditions are the cleaning conditions conventionally used in the art, for example, the ion beam is an argon ion beam or a nitrogen ion beam, the acceleration voltage is 0.2~1.5 kV, the ion beam current is 20~100 mA, and the cleaning time is 5~60 min; the plasma cleaning conditions are the cleaning conditions conventionally used in the art, for example, the plasma working gas is argon or nitrogen, the acceleration voltage is 0.2~1.5 kV, the ion beam current is 20~100 mA, and the cleaning time is 5~60 min.

[0017] Furthermore, in step (6), the optimal injection dose of the metal element is the dose conventionally used in the bearing steel metal element ion injection technology, for example, 1.0×10 16 ions / cm 2 ~ 1.0×10 18 ions / cm 2 .

[0018] Furthermore, in step (6), the gas element is a common gas element in the bearing steel gas element ion implantation technology, and nitrogen is used as an example in the specific embodiment of the present invention; the implantation conditions of the gas element are the conditions conventionally used in the bearing steel gas element ion implantation technology, for example: the implantation voltage is 40 kV to 100 kV, the implantation dose is 1.0×10 16 ions / cm 2 ~ 1.0×10 18 ions / cm 2 .

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The present invention uses SRIM software to perform ion implantation simulation based on the main components of the bearing steel or bearing element to be surface treated and the types of metal elements to be selected, and obtains the vacancy-to-injection ion number ratio of each metal element. The metal element with the highest vacancy-to-injection ion number ratio is selected as the optimal implanted metal element. Experimental results show that under the preferred implantation conditions, the friction and wear resistance of the bearing steel or bearing element after ion implantation surface treatment is most improved under oil-starved working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the process of the present invention.

[0022] Figure 2 This is a comparison chart of the friction coefficient under oil-starved conditions after the surface treatment of M50 bearing steel using the method of the present invention.

[0023] Figure 3 The figure is a comparison chart of the wear rate under oil-starved conditions after the surface treatment of M50 bearing steel using the method of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0025] Example 1

[0026] 1. Material preparation:

[0027] The main components of the bearing steel used in this embodiment are shown in Table 1:

[0028] Element Fe Cr Mo V C Si Mn Ni Co W Cu content / % 88.35 4.00 4.25 1.00 0.80 0.35 0.35 0.20 0.25 0.25 0.20

[0029] The bearing steel was machined into samples with a diameter of 24.0 mm and a thickness of 7.9 mm. The sample surface was polished to a roughness Ra of less than 20 nm using sandpaper and a polishing machine.

[0030] 2. Calculation of the Vacancy-Implanted Ion Ratio: Five metal elements were selected as candidates: titanium (Ti), zirconium (Zr), niobium (Nb), nickel (Ni), and tantalum (Ta). A matrix layer was created in the SRIM software based on the main components of the bearing steel shown in Table 1. An injection voltage of 50 kV and 10,000 elements were selected for each of the five metal elements. The vacancy-to-implanted ion ratios for each of the five proposed metal elements were extracted and compared from the output results. The results, from highest to lowest, were: niobium 4201.3, tantalum 3329.4, zirconium 3158.7, nickel 2146.8, and titanium 2122.3.

[0031] 3. Sample cleaning: The sample surface was cleaned using an argon ion beam with an accelerating voltage of 600 V, a beam current of 30 mA, and a cleaning time of 20 min.

[0032] 4. Metal element implantation: The ion implantation acceleration voltage is 50 kV and the implantation dose is 2×10 17 ions / cm 2 The cleaned samples were injected with niobium, zirconium and nickel respectively.

[0033] 5. Gas element injection: Inject gas elements onto the sample surface after metal element injection. The ion injection acceleration voltage is 80 kV and the injection dose is 2×10 17 ions / cm 2 To facilitate the distinction of the three groups of implanted samples, the three groups of samples implanted with niobium + nitrogen, zirconium + nitrogen, and nickel + nitrogen are marked as Nb + N, Zr + N, and Ni + N, respectively.

[0034] 6. Oil-starved friction and wear resistance testing: Oil-starved friction and wear resistance tests were conducted on samples without injection and after injection of different metal elements. The lubricant was Mobile Jet Oil II (5 μL), the test load was 15 N, the rotation speed was 1500 rpm, the test duration was 30 min, and the counterpart was a 5.6 mm diameter steel ball (with the same composition as the sample).

[0035] 7. Implementation effect: Figure 2As shown, the friction coefficient is Nb+N < Zr+N < Ni+N < un-injected bearing steel, indicating that the injection of metal elements and gas elements reduces the friction coefficient of the bearing steel. Moreover, compared with zirconium and nickel, the friction coefficient of the sample with niobium having the highest vacancy-injected ion number ratio is the smallest. As Figure 3 shown, the wear rate is Nb+N < Zr+N < Ni+N < un-injected bearing steel, indicating that the injection of metal elements and gas elements reduces the wear rate of the bearing steel. Moreover, compared with zirconium and nickel, the wear rate of the sample with niobium having the highest vacancy-injected ion number ratio is the smallest.

[0036] The above results show that selecting the metal element with the highest vacancy-injected ion number ratio as the best injected metal element has the best effect on reducing the friction coefficient and wear rate of oil-starved lubrication bearing steel or bearing components, and can greatly improve the friction and wear resistance of bearing steel or bearing components under the special working condition of oil-starved lubrication.

[0037] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A bearing steel ion implantation surface treatment method, characterized in that: The steps include: (1) In the SRIM software, set the main component of the substrate layer to be consistent with the main component of the bearing steel or bearing element to be surface treated, and set the metal element injection voltage or energy and the number of injections; (2) Start the SRIM software to perform ion implantation simulation calculation on the metal element to be selected, and extract the ratio of the number of vacancies and implanted ions generated by the metal element to be selected in the bearing steel or bearing component to be surface treated in the output result. The metal element to be selected is titanium, chromium, nickel, zirconium, niobium, molybdenum, tantalum, silver or tungsten; (3) Replace other metal elements to be selected and repeat steps (1) to (2) until the vacancy-injection ion number ratios of all metal elements to be selected are obtained; (4) Selecting a metal element with a high vacancy-to-injection ratio as the optimal implantation metal element; (5) Perform ion beam or plasma cleaning on the bearing steel or bearing components to be surface treated in a vacuum chamber before implantation; (6) According to the metal element injection voltage or energy set in step (1), the optimal metal element is ion-injected on the surface of the cleaned bearing steel or bearing component, and then the gas element is injected; or the gas element is first injected on the surface of the cleaned bearing steel or bearing component, and then according to the metal element injection voltage or energy set in step (1), the optimal metal element is ion-injected on the surface of the cleaned bearing steel or bearing component; The optimal injection dose of metal elements is 1.0×10 16 ions / cm 2 ~1.0×10 18 ions / cm 2 The gas element is nitrogen. The injection conditions of the gas element are: injection voltage of 40 kV ~ 100 kV, injection dose of 1.0×10 16 ions / cm 2 ~ 1.0×10 18 ions / cm 2 .

2. The bearing steel ion implantation surface treatment method according to claim 1, characterized in that: In step (1) or (6), the injection voltage is 20 kV to 70 kV.

3. The bearing steel ion implantation surface treatment method according to claim 1, characterized in that: In step (1), the number of injections is more than 1000.

4. The bearing steel ion implantation surface treatment method according to claim 1, characterized in that: In step (1), the number of injections is 1000~10000.

5. The bearing steel ion implantation surface treatment method according to claim 1, characterized in that: In step (5), the ion beam cleaning conditions are: the ion beam is an argon ion beam or a nitrogen ion beam, the acceleration voltage is 0.2~1.5 kV, the ion beam current is 20~100 mA, and the cleaning time is 5~60 min; the plasma cleaning conditions are: the plasma working gas is argon or nitrogen, the acceleration voltage is 0.2~1.5 kV, the ion beam current is 20~100 mA, and the cleaning time is 5~60 min.

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