Titanium metal surface high hardness carbonized layer and preparation method thereof

Abstract

The application discloses a preparation method of a high-hardness carbonized layer on a titanium metal surface, which comprises the following steps: step 1, selecting high-purity graphite as a carbon diffusion source and selecting high-strength titanium alloy as a base titanium alloy; step 2, drying the high-strength titanium alloy after cleaning in a vacuum box, and tightly pressing the graphite block on the surface of the high-strength titanium alloy to form a diffusion couple; step 3, connecting positive and negative electrodes to the upper and lower ends of the diffusion couple respectively, and placing the diffusion couple into the vacuum box, so that the atoms at the interface of the high-strength titanium alloy and the graphite diffuse to each other under the action of an electric field, and a TiC wear-resistant layer is prepared on the surface of the high-strength titanium alloy; and step 4, placing the high-strength titanium alloy with the TiC wear-resistant layer on the surface into a vacuum heat treatment furnace for low-temperature annealing treatment, so that a high-hardness carbonized layer is prepared on the surface of the high-strength titanium alloy; the carbonized layer can improve the surface hardness of the titanium alloy and improve the strength and wear resistance of the titanium alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium alloy surface hardening treatment, and particularly relates to a titanium metal surface high-hardness carbonized layer and a preparation method thereof. BACKGROUND

[0002] Compared with other metals, titanium alloy plays an important role in many fields such as aerospace, medical treatment, industry, military and construction due to its unique advantages of low density and high strength ratio. However, the poor wear resistance of titanium alloy limits the further expansion of its application field, and the low wear resistance may cause the titanium alloy parts to be damaged quickly and shorten the service life.

[0003] Titanium carbide has good heat conduction performance, wear resistance and low wear rate, and its grinding capacity is equivalent to that of artificial diamond, and the cost is relatively low, so it becomes one of the ideal choices for manufacturing wear-resistant materials. SUMMARY

[0004] The application aims to provide a preparation method of a titanium metal surface high-hardness carbonized layer, and the prepared carbonized layer can improve the wear resistance of titanium alloy.

[0005] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0006] A preparation method of a titanium metal surface high-hardness carbonized layer, specifically comprising the following steps:

[0007] Step 1, high-purity graphite with high electrical conductivity and high thermal conductivity coefficient is selected as a carbon diffusion source, and high-strength titanium alloy is selected as a base body, the carbon content of the graphite is greater than 99.99%, and the composition of the high-strength titanium alloy is that the Ti content is 55% and the Nb content is 45%;

[0008] Step 2, the high-strength titanium alloy is placed in an ultrasonic cleaning instrument, and the oil stains and waxy organic substances on the surface of the high-strength titanium alloy are removed through alkaline cleaning agent, then the high-strength titanium alloy is dried in a vacuum box, and finally the graphite block is tightly pressed on the surface of the high-strength titanium alloy to form a diffusion couple, the upper end of the diffusion couple is the graphite block, and the lower end is the high-strength titanium alloy, wherein the entire outer surface of the high-strength titanium alloy is pressed with the graphite block;

[0009] Step 3, the positive and negative electrodes are respectively connected to the upper and lower ends of the diffusion couple formed in step 2, and are placed in a vacuum box, under the action of an electric field, the atoms of the high-strength titanium alloy and the graphite diffuse into each other, and a TiC wear-resistant layer is prepared on the surface of the high-strength titanium alloy;

[0010] The vacuum degree of the vacuum box is 10 -2 -10 -3 , and the electric field condition is that the current density is 10-100 A / cm 2, the current frequency is 30-50Hz, the pulse width is 50-100us, the processing time is 20s-5min, and high-purity argon is injected into the vacuum box when cooling to room temperature after the power supply is turned off;

[0011] Step 4: the high-strength titanium alloy with the TiC wear-resistant layer prepared in step 3 is placed in a vacuum heat treatment furnace for low-temperature annealing treatment, and finally a high-hardness carbonized layer is prepared on the surface of the high-strength titanium alloy.

[0012] Further, in step 2, the high-strength titanium alloy is cleaned in the ultrasonic cleaning instrument for 5-10min.

[0013] Further, in step 2, the high-strength titanium alloy is dried in the vacuum box at a temperature of 160℃.

[0014] Further, in step 2, the graphite block is tightly pressed against the surface of the high-strength titanium alloy at a pressure of 50-100MPa.

[0015] Further, in step 4, the low-temperature annealing temperature is 550℃, and the low-temperature annealing time is 1.5h.

[0016] According to the method for preparing a high-hardness carbonized layer on the surface of a titanium metal according to the above, a high-hardness carbonized layer is prepared on the surface of the titanium metal.

[0017] Compared with the prior art, the method has the following beneficial effects:

[0018] The high-strength titanium carbide is generated in situ on the surface of the titanium metal, the preparation time is short, and the wear resistance of the titanium alloy can be effectively improved.

[0019] The high-hardness carbonized layer prepared by the method can form a titanium-carbon compound with strong bonding force and high stability.

[0020] The method adopts electric field-assisted carbon atom diffusion, improves the formation rate of the carbonized layer, and forms a uniform carbonized layer with high production efficiency, simple equipment operation and batch production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a microstructure diagram of the interface between the high-hardness carbonized layer prepared on the surface of the titanium metal according to Example 1 of the present application and the titanium metal substrate.

[0022] Figure 2 FIG. 4 is a microstructure diagram of the high-hardness carbonized layer prepared on the surface of the titanium metal according to Example 4 of the present application. DETAILED DESCRIPTION

[0023] The present application will be described in detail below with reference to the drawings and specific embodiments.

[0024] A method for preparing a high-hardness carbonized layer on a titanium metal surface, specifically comprising the following steps:

[0025] Step 1: high-purity graphite with high electrical conductivity and high thermal conductivity is selected as a carbon diffusion source, and a high-strength titanium alloy is selected as a substrate titanium alloy. The carbon content of the graphite is greater than 99.99%, and the composition of the high-strength titanium alloy is Ti content of 55% and Nb content of 45%.

[0026] Step 2: the high-strength titanium alloy is placed in an ultrasonic cleaning instrument, and the surface of the high-strength titanium alloy is cleaned by an alkaline cleaning agent to remove organic substances such as oil stains and waxiness. The high-strength titanium alloy is cleaned in the ultrasonic cleaning instrument for 5-10 min, and then the high-strength titanium alloy is dried in a vacuum box at a temperature of 160°C. Finally, the graphite block is tightly pressed on the surface of the high-strength titanium alloy to form a diffusion couple. The upper end of the diffusion couple is the graphite block, and the lower end is the high-strength titanium alloy. The entire outer surface of the high-strength titanium alloy is pressed with the graphite block. The pressure used for tightly pressing the graphite block on the surface of the high-strength titanium alloy is 50-100 MPa.

[0027] Step 3: the positive and negative electrodes are connected to the upper and lower ends of the diffusion couple formed in step 2, respectively, and placed in a vacuum box. The vacuum degree of the vacuum box is 10 -2 -10 -3 Under the action of the electric field, the atoms at the interface of the high-strength titanium alloy and the graphite diffuse with each other. The electric field conditions are: current density of 10-100 A / cm 2 , current frequency of 30-50 Hz, pulse width of 50-100 μs, and treatment time of 20 s-5 min. After the power is turned off, it is cooled to room temperature. High-purity argon is injected into the vacuum box during cooling. A TiC wear-resistant layer is prepared on the surface of the high-strength titanium alloy.

[0028] Step 4: the high-strength titanium alloy with the TiC wear-resistant layer on the surface prepared in step 3 is placed in a vacuum heat treatment furnace for low-temperature annealing treatment. The low-temperature annealing temperature is 550°C, and the low-temperature annealing time is 1.5 h. Finally, a high-hardness carbonized layer is prepared on the surface of the high-strength titanium alloy.

[0029] Example 1

[0030] Step 1: high-purity graphite with high electrical conductivity and high thermal conductivity is selected as a carbon diffusion source, and a high-strength titanium alloy is selected as a substrate titanium alloy. The carbon content of the graphite is 99.995%, and the composition of the high-strength titanium alloy is Ti content of 55% and Nb content of 45%.

[0031] Step 2: the surface of the high-strength titanium alloy is cleaned by an alkaline cleaning agent to remove organic substances such as oil stains and waxiness. The high-strength titanium alloy is cleaned in an ultrasonic cleaning instrument for 5 min, and then dried in a vacuum box. Then, the graphite block is tightly pressed on the surface of the titanium alloy to form a diffusion couple. The pressure used is 50 MPa.

[0032] Step 3: connecting positive and negative electrodes on the upper and lower ends of the diffusion couple, and placing it in a vacuum box, under the action of electric field, atoms of titanium and graphite at the interface diffuse into each other, current density 10 A / cm 2 , and a TiC wear-resistant layer is prepared. The vacuum degree is 10 -2 , current frequency 50 Hz, pulse width 50 μs, processing time 50 s, and high-purity argon is injected during cooling.

[0033] Step 4: placing the titanium metal with high-hardness carbonized layer into a vacuum heat treatment furnace for low-temperature annealing treatment, low-temperature annealing temperature 550 ℃, holding time 1.5 h, so that the structure of the carbonized layer on the surface of the alloy is more stable, while the toughness and ductility of the core material are maintained, and finally a high-hardness carbonized layer is prepared on the surface of the high-strength titanium alloy.

[0034] Figure 1 The interface microstructure diagram of the high-hardness carbonized layer prepared on the surface of the titanium metal of Example 1 and the titanium alloy substrate can be seen from Figure 1 , the diffusion interface is clear, and there are no macroscopic defects such as delamination and peeling. The depth of the carburized layer reaches 58 μm, the average microhardness of the surface of the titanium alloy is 947.5 HV 0.02 , the friction coefficient is 0.231, the volume wear rate is 5.12 × 10 - 6 mm 3 / N.m, and it has good wear resistance.

[0035] Example 2

[0036] Step 1: selecting high-purity graphite with high electrical conductivity and high thermal conductivity as the carbon diffusion source, and selecting high-strength titanium alloy as the substrate. The carbon content of the graphite is 99.995%, and the composition of the high-strength titanium alloy is Ti content 55% and Nb content 45%.

[0037] Step 2: removing surface cleaning oil, wax and other organic substances on the surface of the high-strength titanium alloy by an alkaline cleaning agent, cleaning in an ultrasonic cleaning instrument for 8 min, drying in a vacuum box, then tightly pressing the graphite block on the surface of the titanium alloy to form a diffusion couple, and the pressure used is 80 MPa.

[0038] Step 3: connecting positive and negative electrodes on the upper and lower ends of the diffusion couple, and placing it in a vacuum box, under the action of electric field, atoms of titanium and graphite at the interface diffuse into each other, current density 10 A / cm 2 , and a TiC wear-resistant layer is prepared. The vacuum degree is 10 -3 , current frequency 30 Hz, pulse width 100 μs, processing time 1 min, and high-purity argon is injected during cooling.

[0039] Step 4: Place the titanium metal with the high-hardness carbide layer into a vacuum heat treatment furnace for low-temperature annealing to stabilize the carbide layer structure on the alloy surface while maintaining the toughness and ductility of the core material. The low-temperature annealing temperature is 550℃, and the holding time is 1.5h.

[0040] Example 2 prepared a high-hardness carbide layer on the titanium metal surface, with a carburized layer depth of 68 μm and an average microhardness of 960.21 HV on the alloy surface. 0.02 The coefficient of friction is 0.225, and the volumetric wear rate is 4.36 × 10. -6 mm 3 / Nm, exhibiting good wear resistance.

[0041] Example 3

[0042] Step 1: Select high-purity graphite with high electrical and thermal conductivity as the carbon diffusion source, and choose a high-strength titanium alloy as the matrix. The graphite contains 99.995% carbon, and the high-strength titanium alloy has a Ti content of 55% and a Nb content of 45%.

[0043] Step 2: Remove surface oil, wax and other organic substances from the high-strength titanium alloy surface with an alkaline cleaning agent, clean in an ultrasonic cleaning instrument for 10 minutes, dry in a vacuum chamber, and then press a graphite block tightly onto the titanium alloy surface to form a diffusion couple at a pressure of 100 MPa.

[0044] Step 3: Connect positive and negative electrodes to the upper and lower ends of the diffusion couple and place it in a vacuum chamber. Under the action of an electric field, the interface atoms of titanium and graphite diffuse into each other, with a current density of 50 A / cm². 2 A TiC wear-resistant layer was prepared under a vacuum degree of 10. -3 The current frequency was 40Hz, the pulse width was 50μs, the processing time was 1min, and high-purity argon gas was injected during cooling.

[0045] Step 4: Place the titanium metal with the high-hardness carbide layer into a vacuum heat treatment furnace for low-temperature annealing to stabilize the carbide layer structure on the alloy surface while maintaining the toughness and ductility of the core material. The low-temperature annealing temperature is 550℃, and the holding time is 1.5h.

[0046] Example 3 prepared a high-hardness carbide layer on the titanium metal surface, with a carburized layer depth of 75 μm and an average microhardness of 1020.13 HV on the alloy surface. 0.02 The coefficient of friction is 0.205, and the volumetric wear rate is 2.58 x 10. -6 mm 3 / Nm, exhibiting good wear resistance.

[0047] Example 4

[0048] Step 1: Select high-purity graphite with high electrical and thermal conductivity as the carbon diffusion source, and choose a high-strength titanium alloy as the matrix. The graphite contains 99.995% carbon, and the high-strength titanium alloy has a Ti content of 55% and a Nb content of 45%.

[0049] Step 2: Remove surface oil, wax and other organic substances from the high-strength titanium alloy surface with an alkaline cleaning agent, clean in an ultrasonic cleaning instrument for 5 minutes, dry in a vacuum chamber, and then press a graphite block tightly onto the titanium alloy surface to form a diffusion couple at a pressure of 50 MPa.

[0050] Step 3: Connect positive and negative electrodes to the upper and lower ends of the diffusion couple and place it in a vacuum chamber. Under the action of an electric field, the interface atoms of titanium and graphite diffuse into each other, with a current density of 75 A / cm². 2 A TiC wear-resistant layer was prepared under a vacuum degree of 10. -2 The current frequency was 50 Hz, the pulse width was 50 μs, the processing time was 5 min, and high-purity argon gas was injected during cooling.

[0051] Step 4: Place the titanium metal with the high-hardness carbide layer into a vacuum heat treatment furnace for low-temperature annealing to stabilize the carbide layer structure on the alloy surface while maintaining the toughness and ductility of the core material. The low-temperature annealing temperature is 550℃, and the holding time is 1.5h.

[0052] Figure 2 This is a microstructure image of the high-hardness carbide layer prepared on the surface of titanium metal in Example 4 of the present invention. The image shows that the carbide layer is uniformly formed. The high-hardness carbide layer on the titanium metal surface prepared in Example 4 has a carburized layer depth of 85 μm and an average microhardness of 990.56 HV on the alloy surface. 0.02 The coefficient of friction is 0.215, and the volumetric wear rate is 3.27 x 10. -6 mm 3 / Nm, exhibiting good wear resistance.

[0053] Example 5

[0054] Step 1: Select high-purity graphite with high electrical and thermal conductivity as the carbon diffusion source, and choose a high-strength titanium alloy as the matrix. The graphite contains 99.995% carbon, and the high-strength titanium alloy has a Ti content of 55% and a Nb content of 45%.

[0055] Step 2: Remove surface oil, wax and other organic substances from the high-strength titanium alloy surface with an alkaline cleaning agent, clean in an ultrasonic cleaning instrument for 5 minutes, dry in a vacuum chamber, and then press a graphite block tightly onto the titanium alloy surface to form a diffusion couple at a pressure of 50 MPa.

[0056] Step 3: Connect positive and negative electrodes to the upper and lower ends of the diffusion couple and place it in a vacuum chamber. Under the action of an electric field, the interface atoms of titanium and graphite diffuse into each other at a current density of 100 A / cm². 2 A TiC wear-resistant layer was prepared under a vacuum degree of 10. -3 The current frequency is 50Hz, the pulse width is 100μs, the processing time is 20s, and high-purity argon gas is injected during cooling.

[0057] Step 4: Place the titanium metal with the high-hardness carbide layer into a vacuum heat treatment furnace for low-temperature annealing to stabilize the carbide layer structure on the alloy surface while maintaining the toughness and ductility of the core material. The low-temperature annealing temperature is 550℃, and the holding time is 1.5h.

[0058] In Example 5, the titanium metal surface has a high-hardness carbide layer with a carburized layer depth of 90 μm, and the average microhardness of the alloy surface is 899.32 HV. 0.02 The coefficient of friction is 0.312, and the volumetric wear rate is 1.12 x 10. -5 mm 3 / Nm, exhibiting good wear resistance.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-hardness carbide layer on the surface of titanium metal, characterized in that, Specifically, the following steps are included: Step 1: Select high-purity graphite with high electrical and thermal conductivity as the carbon diffusion source. The matrix titanium alloy is a high-strength titanium alloy. The graphite has a carbon content greater than 99.99%, and the high-strength titanium alloy has a Ti content of 55% and a Nb content of 45%. Step 2: Place the high-strength titanium alloy in an ultrasonic cleaning instrument and clean it with an alkaline cleaning agent to remove oil, wax, and organic substances from the surface of the high-strength titanium alloy. Then, place the high-strength titanium alloy in a vacuum chamber to dry it. Finally, press a graphite block tightly onto the surface of the high-strength titanium alloy to form a diffusion couple. The upper end of the diffusion couple is a graphite block, and the lower end is the high-strength titanium alloy. The entire outer surface of the high-strength titanium alloy is covered with a graphite block. Step 3: Connect positive and negative electrodes to the upper and lower ends of the diffusion couple formed in step 2, and place them in a vacuum box. Under the action of an electric field, the interfacial atoms of the high-strength titanium alloy and graphite diffuse into each other, and a TiC wear-resistant layer is prepared on the surface of the high-strength titanium alloy. The vacuum chamber has a vacuum level of 10. -2 -10 -3 The electric field conditions are: current density 10⁻¹⁰⁰ A / cm² 2 The current frequency is 30-50Hz, the pulse width is 50-100μs, the processing time is 20s-5min, and after the power is turned on, it is cooled to room temperature. High-purity argon gas is injected into the vacuum chamber during the cooling process. Step 4: The high-strength titanium alloy with a TiC wear-resistant layer on the surface prepared in Step 3 is placed in a vacuum heat treatment furnace for low-temperature annealing treatment, and finally a high-hardness carbide layer is prepared on the surface of the high-strength titanium alloy.

2. The method for preparing a high-hardness carbide layer on a titanium metal surface according to claim 1, characterized in that, In step 2, the high-strength titanium alloy is cleaned in an ultrasonic cleaning instrument for 5-10 minutes.

3. The method for preparing a high-hardness carbide layer on a titanium metal surface according to claim 1, characterized in that, In step 2, the high-strength titanium alloy is dried in a vacuum chamber at a temperature of 160°C.

4. The method for preparing a high-hardness carbide layer on a titanium metal surface according to claim 1, characterized in that, In step 2, the pressure used to press the graphite block tightly onto the surface of the high-strength titanium alloy is 50-100 MPa.

5. The method for preparing a high-hardness carbide layer on a titanium metal surface according to claim 1, characterized in that, In step 4, the low-temperature annealing temperature is 550℃ and the low-temperature annealing time is 1.5h.

6. A method for preparing a high-hardness carbide layer on a titanium metal surface according to any one of claims 1-5, wherein a high-hardness carbide layer is prepared on a titanium metal surface.

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