A titanium alloy wear-resistant and ablation-resistant composite strengthening layer and its preparation method

Abstract

The present invention relates to the technical field of titanium alloy surface treatment, and specifically to a titanium alloy wear-resistant and ablation-resistant composite strengthening layer and a preparation method thereof. The surface of a titanium alloy substrate is ground and then ultrasonically cleaned; a mechanical shot peening method is used to perform surface plastic deformation pretreatment on the cleaned titanium alloy to form a diffusion channel; plasma nitriding is performed on the titanium alloy after surface plastic deformation to obtain a titanium alloy with a surface composite strengthening. Based on the poor wear resistance and ablation resistance of traditional titanium alloys, the present invention uses a spraying composite technology that combines mechanical shot peening and plasma nitriding to prepare a wear-resistant nanocrystalline structure compound layer, an ablation-resistant aluminum-rich layer and an anti-fatigue diffusion layer on the surface of the titanium alloy. The composite strengthening layer has good wear resistance and ablation resistance, can effectively improve the wear and ablation characteristics of the titanium alloy hot end components, and improve the service reliability and safety of the titanium alloy hot end components.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy surface treatment, and in particular to a titanium alloy wear-resistant and ablation-resistant composite strengthening layer and a preparation method thereof. Background Art

[0002] Titanium alloys are sensitive to combustion environments. Oxides produced by oxidation at high temperatures have low density and a loose oxide film, which cannot protect the substrate. The heat released by combustion is much greater than the rate of heat dissipation, which increases the metal temperature and accelerates combustion. This makes it easy for them to catch fire and burn under high temperature, high pressure or severe impact when used as hot-end components in the power systems of aerospace, weapons and other equipment, causing the hot-end components to burn, melt, and burn through, resulting in equipment failure and even safety accidents. Titanium alloys used as hot-end components must withstand high-temperature, high-speed gas erosion, and the main problems to be solved are the flame retardancy and erosion erosion resistance of titanium alloys. At present, coating technology has become the main technology for the application of titanium alloy hot-end components due to its good protective effect and low cost. In order to achieve flame retardancy and erosion erosion resistance of titanium alloys using coating technology, the designed and prepared coating must meet the following requirements: it is flame retardant and can isolate gas; it is resistant to gas erosion and has a small difference in thermal expansion coefficient with the substrate; it has a high bonding strength and a tight bond with the substrate.

[0003] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the Invention

[0004] The purpose of the present invention is to solve the flame retardancy and erosion erosion resistance problems of titanium alloy used as hot end components to withstand high temperature and high speed gas erosion, and provide a titanium alloy wear-resistant and ablation-resistant composite strengthening layer and its preparation method.

[0005] In order to achieve the above object, the present invention discloses a titanium alloy wear-resistant and ablation-resistant composite strengthening layer and a preparation method thereof, comprising the following steps:

[0006] S1, grinding the titanium alloy material, further polishing it to a low roughness state, and cleaning it in acetone or alcohol solution;

[0007] S2, clamping the titanium alloy obtained in step S1 on a tool, and presetting the Almon strength using an arc height meter;

[0008] S3, adjust the horizontal distance between the tooling and the shot peening gun muzzle, select the shot peening material, the incident angle of the muzzle, the flow rate and the pressure of the shot peening gun muzzle, and shot peen for 40 seconds to obtain the surface nano-crystallized titanium alloy sample;

[0009] S4, cleaning the titanium alloy sample obtained in step S3 in acetone or alcohol solution;

[0010] S5, placing the material obtained in step S4 in a plasma nitriding furnace, evacuating the furnace, and applying voltage;

[0011] S6, introducing nitrogen, hydrogen / argon, adjusting the temperature and pressure in the furnace, and performing heat preservation and nitriding to obtain a composite strengthening layer;

[0012] S7, then the sample is cooled to room temperature in the furnace and taken out.

[0013] In step S1, the titanium alloy material is a high-strength TC11 alloy.

[0014] In step S2, the titanium alloy material is further polished to a mirror surface.

[0015] In step S2, Almon is a type A test piece.

[0016] In step S3, the horizontal distance is 120 mm, the shot peening material is AZB425 ceramic shot, the incident angle is 90°, the flow rate is 3 kg / min, and the key parameter pressure is 0.25-0.50 MPa.

[0017] In step S5, the voltage is 600-700V.

[0018] In step S6, the amount of nitrogen introduced is 100-300 sccm, and the amount of hydrogen / argon introduced is 100-300 sccm.

[0019] In step S6, the nitriding temperature is 750-850° C., the nitriding time is more than 10 hours, and the pressure in the furnace is 200-250 Pa.

[0020] The invention also discloses a titanium alloy wear-resistant and ablation-resistant composite strengthening layer prepared by the preparation method.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The present invention provides a wear-resistant and ablation-resistant composite strengthening layer suitable for titanium alloys. The surface strengthening layer is prepared by spray-infiltration composite technology, which has excellent bonding strength, the coating will not peel off, and has good impact and ablation resistance.

[0023] 2. The present invention provides a wear-resistant and ablation-resistant composite strengthening layer suitable for titanium alloys. The surface layer has a nanocrystalline structure, which can significantly improve the material's wear resistance and erosion resistance. The diffusion layer introduces residual stress to ensure that it does not crack during deformation, and has excellent fatigue resistance. The aluminum-rich layer is located between the compound layer and the diffusion layer. After high-temperature oxidation, it can form aluminum oxide to prevent high-temperature gases, especially oxygen, from contacting the substrate, thereby further improving the ablation resistance.

[0024] 3. The present invention provides a wear-resistant and ablation-resistant composite strengthening layer suitable for titanium alloys. By synergizing a compound layer, an aluminum-rich layer, and a diffusion layer with a specific structure, the composite strengthening layer has excellent resistance to high-temperature wear and high-temperature flame ablation, and can effectively improve the wear and ablation characteristics of titanium alloy hot-end components, thereby improving the reliability and safety of titanium alloy hot-end components.

[0025] 4. The preparation method of the present invention is easy to control and operate, has low cost and is pollution-free, and ensures excellent effect of the composite layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The cross-sectional morphology after shot peening in the embodiment of the present invention;

[0027] Figure 2 The cross-sectional morphology of the spraying composite layer in the embodiment of the present invention;

[0028] Figure 3 This is the cross-sectional morphology after shot peening in Comparative Example 1 of the present invention;

[0029] Figure 4 This is the cross-sectional morphology of the nitrided layer in Comparative Example 5 of the present invention;

[0030] Figure 5 Schematic diagram of the structure of the composite strengthening layer in an embodiment of the present invention;

[0031] Figure 6 The surface hardness of the embodiment of the present invention and the comparative example;

[0032] Figure 7 The wear rate test results of the embodiment of the present invention and the comparative example are shown;

[0033] Figure 8 The mass ablation rate test results of the embodiment of the present invention and the comparative example are shown. DETAILED DESCRIPTION

[0034] The above and other technical features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

[0035] Example

[0036] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0037] S2: The TC11 titanium alloy sample obtained in S1 is clamped on the fixture, and the Almon strength is pre-set using an arc height meter;

[0038] S3: Adjust the horizontal distance between the sample and the shot peening gun muzzle to 120 mm, select AZB425 ceramic shot peening material, the muzzle incident angle is 90°, the flow rate is 3 kg / min, the shot peening gun muzzle pressure is 0.25-0.50 MPa, and start preparing the titanium alloy deformation layer;

[0039] S4: Clean the titanium alloy sample obtained in S3 in acetone or alcohol solution;

[0040] S5: placing the material obtained in step 4 in a plasma nitriding furnace, evacuating the vacuum to 50 Pa, and turning on the voltage to 700 V;

[0041] S6: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 800°C and the pressure was 200 Pa, and the temperature was kept at this temperature for 10 hours to obtain a composite strengthening layer;

[0042] S7: The sample is then cooled to room temperature in the furnace and taken out.

[0043] The cross section of the titanium alloy deformation layer obtained in step S3 is as follows Figure 1 As shown in the figure, it can be seen that the grains are refined and diffusion channels of Al and N elements are formed. The composite strengthening layer obtained in step S6 is as shown in the figure. Figure 2 As shown, it can be seen that a compound layer, an aluminum-rich layer and a diffusion layer are formed. The schematic diagram of the composite strengthening layer structure is shown in Figure 5 The surface hardness of the strengthening layer is shown in Figure 6 As shown in Figure 2, a high temperature friction and wear test (800°C) was conducted, and the test results are shown in Figure 2. Figure 7 As shown in the figure, a flame ablation test was conducted at 1100℃ for 300s, and the mass ablation rate was as follows: Figure 8 shown.

[0044] Comparative Example 1

[0045] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0046] S2: The TC11 titanium alloy sample obtained in S1 is clamped on the fixture, and the Almon strength is pre-set using an arc height meter;

[0047] S3: Adjust the horizontal distance between the sample and the shot peening gun muzzle to 120 mm, select AZB425 ceramic shot peening material, the muzzle incident angle is 90°, the flow rate is 3 kg / min, the shot peening gun muzzle pressure is 0.10-0.25 MPa, and start preparing the titanium alloy deformation layer;

[0048] S4: Clean the titanium alloy sample obtained in S3 in acetone or alcohol solution;

[0049] S5: placing the material obtained in step 4 in a plasma nitriding furnace, evacuating the vacuum to 50 Pa, and turning on the voltage to 700 V;

[0050] S6: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 800°C and the pressure was 200 Pa, and the temperature was kept at this temperature for 10 hours to obtain a composite strengthening layer;

[0051] S7: The sample is then cooled to room temperature in the furnace and taken out.

[0052] Due to insufficient pressure at the shot peening gun muzzle, Figure 3 It shows that the surface grain refinement of Comparative Example 1 is not as good as that of the embodiment, which affects the diffusion channel. The corresponding hardness, wear and ablation test results are not as good as those of the embodiment. Figure 6 、 7 and 8.

[0053] Comparative Example 2

[0054] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0055] S2: The TC11 titanium alloy sample obtained in S1 is clamped on the fixture, and the Almon strength is pre-set using an arc height meter;

[0056] S3: Adjust the horizontal distance between the sample and the shot peening gun muzzle to 120 mm, select AZB425 ceramic shot peening material, the muzzle incident angle is 90°, the flow rate is 3 kg / min, the shot peening gun muzzle pressure is 0.50-0.60 MPa, and start preparing the titanium alloy deformation layer;

[0057] S4: Clean the titanium alloy sample obtained in S3 in acetone or alcohol solution;

[0058] S5: placing the material obtained in step 4 in a plasma nitriding furnace, evacuating the vacuum to 50 Pa, and turning on the voltage to 700 V;

[0059] S6: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 800°C and the pressure was 200 Pa, and the temperature was kept at this temperature for 10 hours to obtain a composite strengthening layer;

[0060] S7: The sample is then cooled to room temperature in the furnace and taken out.

[0061] Due to the high pressure at the shot peening gun nozzle, the surface deformation of comparative example 2 was serious, the surface roughness was large, micro cracks appeared, and the corresponding hardness, wear and ablation test results were not as good as those of the embodiment. Figure 6 、 7and 8.

[0062] Comparative Example 3

[0063] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0064] S2: The TC11 titanium alloy sample obtained in S1 is clamped on the fixture, and the Almon strength is pre-set using an arc height meter;

[0065] S3: Adjust the horizontal distance between the sample and the shot peening gun muzzle to 120 mm, select AZB425 ceramic shot peening material, the muzzle incident angle is 90°, the flow rate is 3 kg / min, the shot peening gun muzzle pressure is 0.25-0.50 MPa, and start preparing the titanium alloy deformation layer;

[0066] S4: Clean the titanium alloy sample obtained in S3 in acetone or alcohol solution;

[0067] S5: placing the material obtained in step 4 in a plasma nitriding furnace, evacuating the vacuum to 50 Pa, and turning on the voltage to 700 V;

[0068] S6: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 700°C and the pressure was 200 Pa, and the temperature was kept at this temperature for 10 hours to obtain a composite strengthening layer;

[0069] S7: The sample is then cooled to room temperature in the furnace and taken out.

[0070] Due to the low nitriding temperature, the surface strengthening effect of Comparative Example 3 is poor, and no thick strengthening protective layer is formed. The corresponding hardness, wear and ablation test results are not as good as those of the embodiment. Figure 6 、 7 and 8.

[0071] Comparative Example 4

[0072] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0073] S2: The TC11 titanium alloy sample obtained in S1 is clamped on the fixture, and the Almon strength is pre-set using an arc height meter;

[0074] S3: Adjust the horizontal distance between the sample and the shot peening gun muzzle to 120 mm, select AZB425 ceramic shot peening material, the muzzle incident angle is 90°, the flow rate is 3 kg / min, the shot peening gun muzzle pressure is 0.25-0.50 MPa, and start preparing the titanium alloy deformation layer;

[0075] S4: Clean the titanium alloy sample obtained in S3 in acetone or alcohol solution;

[0076] S5: placing the material obtained in step 4 in a plasma nitriding furnace, evacuating the vacuum to 50 Pa, and turning on the voltage to 700 V;

[0077] S6: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 900°C and the pressure was 200 Pa, and the temperature was kept at this temperature for 10 hours to obtain a composite strengthening layer;

[0078] S7: The sample is then cooled to room temperature in the furnace and taken out.

[0079] Due to the high nitriding temperature, the surface grains of Comparative Example 4 coarsened, affecting the formation of a continuous aluminum-rich layer, and the corresponding ablation test results were not as good as those of Example 4. Figure 8 shown.

[0080] Comparative Example 5

[0081] S1: Use sandpaper to grind the TC11 titanium alloy material, and further polish it to a low roughness state (mirror state is best), and clean it in acetone or alcohol solution;

[0082] S2: Place the material obtained in step 1 in a plasma nitriding furnace, evacuate the furnace, and turn on the voltage to 700V.

[0083] S3: 200 sccm of nitrogen and 200 sccm of hydrogen were introduced in a ratio of 1:1, the furnace temperature was adjusted to 800°C and the pressure was 200 Pa, and the temperature was kept for 10 hours to obtain a nitrided layer;

[0084] S4: The sample is then cooled to room temperature in the furnace and taken out.

[0085] Comparative Example 5 is a single nitriding strengthening treatment, and there is no continuous aluminum-rich layer on the subsurface. Figure 4 As shown, the ablation resistance is affected, and the corresponding hardness, wear and ablation test results are not as good as those in the embodiment, as shown in FIG. Figure 6 、 7 and 8.

[0086] Comparative Example 6

[0087] TC11 titanium alloy, without any treatment.

[0088] Comparative Example 6 is TC11 titanium alloy, without any treatment, and the corresponding hardness, wear and ablation test results are not as good as those of the embodiment. Figure 6 、 7 and 8.

[0089] The above description is merely a preferred embodiment of the present invention and is intended to be illustrative rather than restrictive of the present invention. Those skilled in the art will appreciate that many changes, modifications, and even equivalents may be made to the present invention within the spirit and scope of the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer, characterized in that: The following steps are involved: S1, grinding the titanium alloy material, further polishing it to a low roughness state, and cleaning it in acetone or alcohol solution; S2, clamping the titanium alloy obtained in step S1 on a tool, and presetting the Almon strength using an arc height meter; S3, adjust the horizontal distance between the tooling and the shot peening gun muzzle, select the shot peening material, the incident angle of the gun muzzle, the flow rate and the pressure of the shot peening gun muzzle, and shot peen for 40 seconds to obtain the surface nano-crystallized titanium alloy sample; S4, cleaning the titanium alloy sample obtained in step S3 in acetone or alcohol solution; S5, placing the material obtained in step S4 in a plasma nitriding furnace, evacuating the furnace, and applying voltage; S6, introducing nitrogen and hydrogen, adjusting the temperature and pressure in the furnace, and nitriding with heat preservation to obtain a composite strengthening layer; S7, the sample is then cooled to room temperature in the furnace, and the sample is taken out, and a nanocrystalline structure compound layer, an ablation-resistant aluminum-rich layer, and an anti-fatigue diffusion layer are formed on the surface of the titanium alloy; In step S3, the horizontal distance is 120 mm, the shot peening material is AZB425 ceramic shot, the incident angle is 90°, the flow rate is 3 kg / min, and the key parameter pressure is 0.25-0.50 MPa; In step S6, the nitriding temperature is 750-850°C.

2. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S1, the titanium alloy material is a high-strength TC11 alloy.

3. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S2, the titanium alloy material is further polished to a mirror surface.

4. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S2, Almon is a type A test piece.

5. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S5, the voltage is 600-700 V.

6. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S6, the amount of nitrogen gas introduced is 100-300 sccm, and the amount of hydrogen gas introduced is 100-300 sccm.

7. The method for preparing a titanium alloy wear-resistant and ablation-resistant composite strengthening layer according to claim 1, characterized in that: In step S6, the nitriding time is more than 10 hours, and the pressure in the furnace is 200-250 Pa.

8. A titanium alloy wear-resistant and ablation-resistant composite strengthening layer prepared by the preparation method according to any one of claims 1 to 7.

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