A method for improving high temperature oxidation resistance and wear resistance of TC4 titanium alloy surface

Abstract

The present invention relates to a method for improving the high-temperature oxidation resistance and wear resistance of the surface of TC4 titanium alloy, and belongs to the technical field of titanium alloy surface treatment. The present invention improves the high-temperature oxidation resistance and wear resistance of the surface of TC4 titanium alloy by preparing a B‑Al‑Si composite infiltration layer on the surface of TC4 titanium alloy, and from the outside to the inside, the B‑Al‑Si composite infiltration layer includes a TiB2 layer, an Al3Ti layer, a Ti5Si3 layer and a diffusion layer in sequence; the thickness of the B‑Al‑Si composite infiltration layer is 20 to 35 μm, and the surface hardness is 2000 to 2800 HV. The Al3Ti layer and the Ti5Si3 layer have good synergistic high-temperature oxidation resistance, and the synergistic effect of the hard phase TiB2 with high hardness, the Al3Ti layer and the Ti5Si3 layer can greatly improve the high-temperature oxidation resistance and wear resistance of the aluminide coating on the surface of the TC4 titanium alloy.

Description

Technical Field

[0001] The invention relates to a method for improving high-temperature oxidation resistance and wear resistance of a TC4 titanium alloy surface, belonging to the technical field of titanium alloy surface treatment. Background Art

[0002] Titanium and its alloys are widely used in vehicle engineering, aerospace, marine vessels, energy chemical industry, biomedicine and other fields due to their high melting point, high specific strength, good corrosion resistance, strong high temperature stability, excellent biocompatibility, non-magnetic and non-toxic properties. However, when the temperature of traditional titanium alloy exceeds 550℃, titanium will react strongly with oxygen to form TiO 2 The protective film is loose and porous, and the high temperature protection effect is poor, so they can only be used under high temperature working conditions of 350-600℃. In addition, titanium and its alloys have low hardness and poor wear resistance, and are prone to adhesive wear during sliding, which can cause the workpiece to bite. The above shortcomings seriously restrict the wider engineering application of titanium and its alloys.

[0003] The preparation of surface protective coating is an effective way to improve the high temperature oxidation resistance and wear resistance of titanium alloy. The commonly used high temperature protective coating is aluminide coating, but the interdiffusion of elements between aluminide coating and titanium alloy substrate at high temperature is serious, which accelerates the failure of coating. Therefore, modified aluminide coating Al-Si coating has gradually developed and matured, inducing the coating to form a stable protective oxide layer (Al2O3) in the service environment. 2 O 3 and SiO 2 etc.), reducing the interdiffusion of the coating and the substrate bond, thereby improving the coating's resistance to high temperature oxidation and thermal corrosion. However, the addition of silicon to the high temperature oxidation resistant coating reduces the thickness of the coating, and the more silicon content, the thinner the total thickness of the generated co-penetration coating. This is extremely detrimental to the surface hardness and wear resistance of the alloy. Summary of the invention

[0004] Aiming at the problems that the existing aluminide coating on the surface of TC4 titanium alloy has poor high-temperature oxidation resistance, short service life of the infiltration layer caused by low surface hardness and poor wear resistance, the present invention proposes a method for improving the high-temperature oxidation resistance and wear resistance of the surface of TC4 titanium alloy. A B-Al-Si composite infiltration layer is prepared on the surface of TC4 titanium alloy. Al 3 Ti and Ti 5 Si 3 High temperature oxidation resistance of the phase and the hard phase TiB 2 The high hardness of the TiB phase 2 Layer, Al 3 Ti layer, Ti 5 Si 3The B-Al-Si composite diffusion layer composed of a layer and a diffusion layer makes up for the defects of insufficient high-temperature oxidation resistance and low surface hardness of the aluminide coating on the surface of the titanium alloy, increases the service life of the TC4 titanium alloy, enhances its service safety and broadens its application field.

[0005] A method for improving the high temperature oxidation resistance and wear resistance of a TC4 titanium alloy surface, wherein a B-Al-Si composite infiltration layer is prepared on the surface of the TC4 titanium alloy, wherein the B-Al-Si composite infiltration layer comprises TiB 2 Layer, Al 3 Ti layer, Ti 5 Si 3 layer and diffusion layer.

[0006] The B-Al-Si composite diffusion layer has a thickness of 20 to 35 μm and a surface hardness of 2000 to 2800 HV.

[0007] The preparation method of the B-Al-Si composite infiltration layer comprises the following specific steps:

[0008] (1) Pretreatment of the TC4 titanium alloy substrate: surface degreasing, grinding, and ultrasonic cleaning;

[0009] (2) The pretreated TC4 titanium alloy substrate and the penetrant are sealed, placed at a temperature of 1000-1100°C for high temperature treatment for 10-20 hours, cooled along with the furnace, and the residual penetrant and impurities are cleaned to obtain a B-Al-Si composite penetrant layer on the surface of the TC4 titanium alloy, wherein the penetrant is a mixture of aluminum powder, silicon powder, boron powder, ammonium chloride and aluminum oxide.

[0010] Taking the mass of the penetrant as 100%, aluminum powder accounts for 15-18%, silicon powder accounts for 4-5%, boron powder accounts for 15-18%, ammonium chloride accounts for 1-4%, and the rest is aluminum oxide.

[0011] The present invention generates a B-Al-Si composite infiltration layer in a TC4 titanium alloy matrix to improve the high temperature oxidation resistance and wear resistance of the TC4 titanium alloy surface, and generates TiB on the surface of the TC4 titanium alloy by a B-Al-Si co-infiltration method. 2 、Al 3 Ti and Ti 5 Si 3 A composite carburized layer with a thickness of not less than 20 μm and a surface microhardness of not less than 2000 HV1 is obtained, so as to achieve the purpose of improving the wear resistance and high temperature oxidation resistance of TC4 titanium alloy.

[0012] The beneficial effects of the present invention are:

[0013] The present invention adopts the co-penetration B-Al-Si process to prepare TiB on the surface of TC4 titanium alloy. 2 ,Al 3Ti and Ti 5 Si 3 The composite infiltration layer is composed of phases, the surface hardness of the infiltration layer can reach above 2000HV1, the thickness of the infiltration layer can reach above 20μm, and the high-temperature oxidation resistance can be maintained above the secondary oxidation resistance level, which can effectively improve the wear resistance and high-temperature oxidation resistance of TC4 titanium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a cross-sectional scanning electron microscope (SEM) image of the surface of TC4 of Example 1 after B-Al-Si co-penetration for 1000°C-15h;

[0015] Figure 2 This is the EDS surface scanning image of the TC4 surface of Example 1 after B-Al-Si co-penetration for 1000°C-15h;

[0016] Figure 3 This is the cross-sectional SEM image of the surface of TC4 in Example 2 after B-Al-Si co-penetration at 1100℃-20h. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0018] Embodiment 1: A method for improving the high temperature oxidation resistance and wear resistance of TC4 titanium alloy surface, wherein a B-Al-Si composite infiltration layer is prepared on the surface of TC4 titanium alloy by a co-infiltration B-Al-Si process, wherein the B-Al-Si composite infiltration layer comprises TiB 2 Layer, Al 3 Ti layer, Ti 5 Si 3 layer and diffusion layer; the specific steps are as follows:

[0019] (1) Pretreatment of the TC4 titanium alloy matrix sample: surface degreasing, sandpaper polishing, anhydrous ethanol ultrasonic cleaning, and sealing in anhydrous ethanol for standby use;

[0020] (2) B-Al-Si co-penetration process: The pretreated TC4 titanium alloy matrix sample and the penetrant are sealed in a corundum crucible, placed in a box furnace, and subjected to high temperature treatment at a temperature of 1000°C for 15 hours. After cooling in the furnace, the sample is ultrasonically cleaned in alcohol to remove the residual penetrant and other impurities on the surface; the penetrant is a mixture of aluminum powder, silicon powder, boron powder, ammonium chloride and aluminum oxide, with the mass of the penetrant being 100%, aluminum powder 18%, silicon powder 4.5%, boron powder 18%, ammonium chloride 1% and aluminum oxide 58.5%;

[0021] The cross-sectional scanning electron microscope (SEM) image of the surface of TC4 in this embodiment after B-Al-Si co-penetration for 1000°C-15h is shown in FIG. Figure 1 ,from Figure 1 It can be seen that the outermost layer of the composite infiltration layer is TiB 2 layer (grayish white structure), the second outer layer is Al 3 Ti layer (dark gray structure), with spots of Ti in the sub-outer layer 5 Si 3 phase (gray-white tissue), the innermost layer is the diffusion layer (light gray tissue);

[0022] The EDS surface scan of TC4 surface B-Al-Si co-penetration 1000℃-15h is shown in Figure 2 , the concentration of Ti element increases gradually from the surface to the matrix; the concentration of B element decreases gradually from the surface to the matrix, and the B concentration on the outer surface is the highest; the concentration of Al element is the highest on the subsurface, and the concentration of Al element decreases gradually from the surface to the matrix; Si element is distributed in the composite diffusion layer in a dotted manner;

[0023] The composite diffusion layer of this embodiment is 20.5 μm thick and has a surface microhardness of 2264 HV1. According to the "Test Method for Determination of Oxidation Resistance of Steel and High-temperature Alloys", the composite diffusion layer can still maintain a complete oxidation resistance level after 700°C cyclic oxidation for 200 hours, and can still maintain a secondary oxidation resistance level after 900°C cyclic oxidation for 200 hours.

[0024] Embodiment 2: A method for improving the high temperature oxidation resistance and wear resistance of TC4 titanium alloy surface, wherein a B-Al-Si composite infiltration layer is prepared on the surface of TC4 titanium alloy by a co-infiltration B-Al-Si process, wherein the B-Al-Si composite infiltration layer comprises TiB 2 Layer, Al 3 Ti layer, Ti 5 Si 3 layer and diffusion layer; the specific steps are as follows:

[0025] (1) Pretreatment of the TC4 titanium alloy matrix sample: surface degreasing, sandpaper polishing, anhydrous ethanol ultrasonic cleaning, and sealing in anhydrous ethanol for standby use;

[0026] (2) B-Al-Si co-penetration process: The pretreated TC4 titanium alloy matrix sample and the penetrant are sealed in a corundum crucible, placed in a box furnace, and subjected to high temperature treatment at a temperature of 1100°C for 20 hours. After cooling in the furnace, the sample is ultrasonically cleaned in alcohol to remove the residual penetrant and other impurities on the surface; the penetrant is a mixture of aluminum powder, silicon powder, boron powder, ammonium chloride and aluminum oxide, with the mass of the penetrant being 100%, aluminum powder 18%, silicon powder 4%, boron powder 18%, ammonium chloride 1% and aluminum oxide 59%;

[0027] The cross-sectional SEM image of the surface of TC4 in this embodiment after B-Al-Si co-penetration for 1100°C-20h is shown in Figure 3 ,from Figure 3It can be seen that the outermost layer of the composite infiltration layer is TiB 2 layer (grayish white structure), the second outer layer is Al 3 Ti layer (dark gray structure), with spots of Ti in the sub-outer layer 5 Si 3 phase (gray-white tissue), the innermost layer is the diffusion layer (light gray tissue);

[0028] The composite diffusion layer of this embodiment is 31.9 μm thick and has a surface microhardness of 2780 HV1. According to the "Test Method for Determination of Oxidation Resistance of Steel and High-temperature Alloys", the composite diffusion layer can still maintain a complete oxidation resistance level after 700°C cyclic oxidation for 200 hours, and can still maintain a secondary oxidation resistance level after 900°C cyclic oxidation for 200 hours.

[0029] Embodiment 3: A method for improving the high temperature oxidation resistance and wear resistance of TC4 titanium alloy surface, wherein a B-Al-Si composite infiltration layer is prepared on the surface of TC4 titanium alloy by a co-infiltration B-Al-Si process, wherein the B-Al-Si composite infiltration layer comprises TiB 2 Layer, Al 3 Ti layer, Ti 5 Si 3 layer and diffusion layer; the specific steps are as follows:

[0030] (1) Pretreatment of the TC4 titanium alloy matrix sample: surface degreasing, sandpaper polishing, anhydrous ethanol ultrasonic cleaning, and sealing in anhydrous ethanol for standby use;

[0031] (2) B-Al-Si co-penetration process: The pretreated TC4 titanium alloy matrix sample and the penetrant are sealed in a corundum crucible, placed in a box furnace, and subjected to high temperature treatment at 1100°C for 15 h. After cooling in the furnace, the sample is ultrasonically cleaned in alcohol to remove the residual penetrant and other impurities on the surface; the penetrant is a mixture of aluminum powder, silicon powder, boron powder, ammonium chloride and aluminum oxide, with the mass of the penetrant being 100%, aluminum powder 18%, silicon powder 4.5%, boron powder 18%, ammonium chloride 2% and aluminum oxide 57.5%;

[0032] The outermost layer of the composite infiltration layer of B-Al-Si co-infiltration on the surface of TC4 in this embodiment is TiB 2 layer, the second outer layer is Al 3 Ti layer, with spots of Ti in the sub-outer layer 5 Si 3 phase, the innermost layer is the diffusion layer;

[0033] The composite diffusion layer of this embodiment is 34.8 μm thick and has a surface microhardness of 2300 HV1. According to the “Test Method for Determination of Oxidation Resistance of Steel and High-temperature Alloys”, the composite diffusion layer can still maintain a complete oxidation resistance level after 700°C cyclic oxidation for 200 hours, and can still maintain a secondary oxidation resistance level after 900°C cyclic oxidation for 200 hours.

[0034] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for improving the high temperature oxidation resistance and wear resistance of TC4 titanium alloy surface, Features: A B-Al-Si composite infiltration layer is prepared on the surface of TC4 titanium alloy, the thickness of the B-Al-Si composite infiltration layer is 20-35 μm, and the surface hardness is 2000-2800 HV; The preparation method of the B-Al-Si composite infiltration layer comprises the following specific steps: (1) Pretreatment of the TC4 titanium alloy substrate: surface degreasing, grinding, and ultrasonic cleaning; (2) The pretreated TC4 titanium alloy substrate and the penetrant are sealed, placed at a temperature of 1000-1100°C for high temperature treatment for 10-20 h, cooled along with the furnace, and the residual penetrant and impurities are cleaned to obtain a B-Al-Si composite penetrant layer on the surface of the TC4 titanium alloy, wherein the penetrant is a mixture of aluminum powder, silicon powder, boron powder, ammonium chloride and aluminum oxide; based on the mass of the penetrant as 100%, aluminum powder accounts for 15-18%, silicon powder accounts for 4-5%, boron powder accounts for 15-18%, ammonium chloride accounts for 1-4%, and the rest is aluminum oxide.

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