CN113182520B - Titanium product with titanium carbide reinforced titanium-based composite material hardened layer and preparation method - Google Patents

Abstract

The invention provides a titanium product with a titanium carbide reinforced titanium-based composite material hardened layer and a preparation method thereof, wherein the preparation method comprises the following steps: preparing a pressed blank, namely selecting a titanium raw material and preparing a powder pressed blank by adopting a near-net shaping technology; carburizing, namely soaking the powder pressed compact in a dispersion liquid containing carbonaceous powder for a certain time, taking out the pressed compact and standing the pressed compact; or coating the dispersion liquid containing the carbonaceous powder on the surface of the powder compact, and then standing; and sintering the obtained carburized powder compact at high temperature to obtain the titanium product. The preparation method comprises the steps of soaking the powder pressed compact formed in the near-net shape into dispersion liquid of carbon powder, enabling the carbon powder to penetrate into the powder pressed compact to a certain thickness through capillary action, wherein the thickness can reach a centimeter scale, and then preparing a titanium product with a titanium carbide reinforced titanium-based composite material coating through high-temperature sintering, so that the problem that the thickness of a hard coating in the traditional titanium surface hardening technology is thin is solved.

Description

Titanium product with titanium carbide reinforced titanium-based composite material hardened layer and preparation method

Technical Field

The invention relates to the technical field of powder metallurgy, in particular to a titanium product with a titanium carbide reinforced titanium-based composite material hardened layer and a preparation method thereof.

Background

Titanium and titanium alloy are widely applied to the fields of aerospace, national defense and military industry, biomedical treatment and the like due to a series of advantages of light weight, high strength, corrosion resistance, heat resistance, no magnetism, no toxicity and the like. However, the poor hardness and wear resistance of titanium affects its use in high friction environments. Therefore, the surface hardening technique of titanium products is an effective means for increasing the hardness and reducing the friction coefficient.

The techniques commonly used at present include several surface modification techniques such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), laser surface treatment, thermal oxidation, ion nitridation, and solid state diffusion, and the purpose of these techniques is to form a hard and wear-resistant layer on the surface of titanium. The application of the above techniques enables the formation of hard surface layers containing nitrides, carbides, borides and oxides and/or sub-surface layers rich in nitrogen, carbon, boron, oxygen, but both of these surface and sub-surface layers have their own disadvantages. For example, the coating thicknesses obtained with CVD and PVD techniques are relatively thin (<250 μm); the maximum hardness of the surface layer obtained by using a thermal oxidation method, ion nitriding and oxygen atom and nitrogen atom injection is lower; the method based on the laser surface treatment has the advantages of complex process, high cost and the like.

Therefore, the search for a new surface hardening technology is very significant for expanding the application of the titanium alloy in a high-friction environment.

Disclosure of Invention

The invention mainly aims to provide a titanium product with a titanium carbide reinforced titanium-based composite material hardened layer and a preparation method thereof.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a method of producing a titanium article having a hardened layer of a titanium carbide-reinforced titanium-based composite material.

The preparation method comprises the following steps:

s1: preparing a pressed blank, namely selecting a titanium raw material and preparing a powder pressed blank by adopting a near-net shaping technology;

s2: carburizing, namely soaking the powder pressed compact into dispersion liquid containing carbonaceous powder for a certain time, taking out the pressed compact and standing the pressed compact; or coating the dispersion liquid containing the carbonaceous powder on the surface of the powder compact, and then standing;

s3: and (4) sintering the carburized powder compact obtained in the step (S2) at a high temperature to obtain the titanium product.

Further, the granularity of the titanium raw material is 10-60 mm.

In the invention, the titanium raw material can be prealloyed powder, mixed element titanium or titanium alloy powder, wherein the mixed element titanium or titanium alloy powder can be various titanium alloy grades of TA, TB and TC series.

Further, in step S1, the near net shape forming technique is any one of a die pressing, a cold isostatic pressing, and an injection molding process.

Further, in step S1, the relative density of the powder compact is 50 to 80%. Too low green compact density and too low strength are not beneficial to subsequent operation and can cause cracking in the sintering process; too high a green density can create a labyrinth seal effect, hindering penetration of the carbon-containing dispersion into the green body, making the hard coating too thin in thickness.

Further, in step S2, the carbonaceous powder is a fine carbonaceous powder; the fine carbonaceous powder includes carbon black powder, graphite powder, graphene, and carbon nanotubes.

Further, in step S2, the liquid medium of the dispersion liquid is an organic solvent; the organic solvent is at least one of water, alcohol and acetone.

Further, the weight of the carbonaceous powder in the dispersion is 0.5 to 20%. When the carbon powder is too low, the hard phase ratio in the hard coating is too low, and the surface hardening effect is weak; when the content of the carbonaceous powder is too high, the dispersion effect of the dispersion liquid is sharply reduced, and local hard phase agglomeration is caused, which affects the uniformity of the hard coating.

Further, in the step S2, the soaking time is 1-5 min; the standing time is 2-3 h. The soaking time is an important factor for controlling the thickness of the hard coating, the hard coating is thinner when the soaking time is short, and the hard coating is thicker when the soaking time is long.

Further, the high-temperature sintering adopts an atmosphere sintering or vacuum sintering process; the sintering temperature is 1200-1350 ℃, and the sintering time is 2-5 h.

To achieve the above object, according to a second aspect of the present invention, there is provided a titanium article having a hardened layer of a titanium carbide-reinforced titanium-based composite material.

The titanium product is prepared by the preparation method, wherein:

the hard layer of the titanium product and the dissimilar titanium product are manufactured integrally, and the thickness of the hard layer is 30-1000 mu m.

The invention combines the powder metallurgy technology with the hard coating manufacturing technology, and realizes the short-flow preparation of the titanium product with the titanium carbide (TiC) reinforced titanium-based composite material hardened layer. Meanwhile, the short-flow integrated forming preparation of the hard coating and the matrix alloy is realized, and the manufacturing cost is obviously reduced.

By utilizing the porous characteristic of a powder pressed compact and the capillary permeability of liquid, fine carbonaceous powder is conveyed among titanium powder particles, a compact titanium alloy product is obtained in the subsequent high-temperature sintering process, and TiC reinforced particles are generated in situ, so that a hard coating with controllable thickness and the thickness of 30-1000 mu m can be realized.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 shows the optical microscope image of a titanium alloy article with a TiC hard layer prepared in the example of the present invention.

In the figure:

the left area of the picture is represented as a hard layer; the right area of the picture is indicated as the article base.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

The preparation method combines a powder near-net-shape forming technology with a hard coating preparation technology, utilizes the porous characteristic of a powder pressed compact, conveys fine carbonaceous powder into titanium powder particles through the capillary infiltration effect of liquid, obtains a compact titanium alloy product in the subsequent high-temperature sintering process, and simultaneously generates TiC reinforced particles in situ, thereby realizing a hard coating with a certain thickness.

Moreover, the titanium product with the TiC reinforced titanium-based composite material hardened layer prepared by the preparation method realizes the integrated manufacture of the hard layer and the anisotropic titanium product, and the thickness of the hard layer is controllable and can reach 30-1000 microns.

The following will describe in detail the method for producing a titanium article having a hardened layer of TiC-reinforced titanium-based composite material according to the present invention with reference to specific examples.

Example 1:

preparation of cold-pressed pure titanium gear with TiC-reinforced hard coating

S1: preparing raw materials, selecting-325-mesh hydrogenated dehydrotitanium powder, and uniformly mixing with 3% of stearic acid lubricant.

S2: and (3) cold pressing and forming, namely cold pressing the raw materials in a steel mould to form the gear product. The pressing pressure was 500 MPa.

S3: and (3) carburizing, namely soaking the gear pressed compact in a graphite powder suspension for 1min, and then taking out and standing for 2 h. Wherein the graphite solid content is 3 wt.%.

S4: and (3) vacuum sintering, namely performing vacuum sintering densification on the pressed compact, wherein the maximum temperature is 1200 ℃, and the heat preservation time is 2 hours.

Example 2:

preparation of TC4 microinjection molded product with TiC-reinforced hard coating

S1: preparing raw materials, adopting TC4 spherical prealloying powder with the particle size less than 20 μm.

S2: and (3) preparing a green compact, mixing the powder with a binder, and performing injection molding and degreasing to obtain a near-net-shape powder blank.

S3: and (3) carburizing, namely coating the graphene dispersion liquid on the surface of a powder pressed compact, and standing for 2 hours. Wherein the solid content of graphene in the dispersion is 1 wt.%.

S4: and (3) vacuum sintering, namely performing vacuum sintering densification on the injection molding blank at 1250 ℃ for 2 h.

Example 3:

preparation of TC4 seamless pipe with TiC-reinforced hard coating

S1: preparing raw materials, mixing element hydrogenated and dehydrogenated powder with TC4, wherein the particle size of the powder is less than 50 mu m.

S2: and (3) preparing a green compact, namely filling the powder into a rubber die with a core rod for cold isostatic pressing, wherein the pressure is 200 MPa.

S3: and (3) carburizing, namely soaking the pipe fitting pressed compact in the carbon black powder suspension for 5min, and standing for 2 h. Wherein the graphite solid phase content in the dispersion is 5 wt.%.

S4: and (3) vacuum sintering, namely performing vacuum sintering densification on the cold isostatic pressing blank at 1250 ℃ for 2 h.

The advantages of the preparation method of the present invention will be described in detail by comparative experiments.

First, experimental object

Comparative example 1:

and nitriding the compact Ti-6Al-4V alloy at the temperature of 1000 ℃ in the atmosphere of nitrogen or ammonia gas to obtain the hard coating.

Comparative example 2:

and carrying out solid boronizing treatment on the compact Ti-6Al-4V alloy at 1000 ℃ to obtain the hard coating.

Second, Experimental methods

The thickness of the hard coating layer in the titanium alloy products prepared in examples 1 to 3 and comparative examples 1 to 2 was measured by a conventional detection method in the prior art.

Third, experimental results

The results of the experiments of examples 1-3 and comparative examples 1-2 are summarized in Table 1.

TABLE 1

Group of	Coating thickness/. mu.m	Coating hardness/HV
			Example 1	180±20	550±30
Example 2	30±10	450±20
			Example 3	1000±50	780±20
Comparative example 1	150±20	950±30
			Comparative example 2	80±20	850±30

As can be seen from Table 1, the coating thickness can be significantly increased by adopting the powder compact for compounding the hard phase, and the experimental result shows that the maximum coating thickness can reach 1000 μm and the minimum coating thickness can reach 30 μm. The maximum coating thickness of the traditional Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), laser surface treatment and other processes is 100-200 mu m, and the maximum coating thickness can be increased by about 4-5 times by the process. Meanwhile, the controllable thickness of the coating and the proportion of the hard phase in the coating (namely the hardness of the coating) can be realized by adjusting the process parameters such as the concentration of the carbonaceous suspension, the soaking time and the like. Although the hardness range of the coating is 450-780 HV, the hardness is slightly lower than that of the traditional coating or basically equivalent to that of the traditional coating, and the use requirement is completely met.

The invention has the advantages that the powder metallurgy technology and the hard coating synthesis are integrated, so that the coating difficulty and the production and processing cost of the hard coating are reduced. Meanwhile, the invention can solve the problem of integral manufacture of some complicated-shaped special-shaped parts with hard layers, and can generate great application and market values by combining powder metallurgy processes such as powder injection molding, powder cold pressing and sintering and the like.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (10)

1. A method for preparing a titanium product with a titanium carbide reinforced titanium-based composite material hardened layer is characterized by comprising the following steps:

s1: preparing a pressed blank, namely selecting a titanium raw material and preparing a powder pressed blank by adopting a near-net-shape forming technology;

s2: carburizing, namely soaking the powder pressed compact into dispersion liquid containing carbonaceous powder for a certain time, taking out the pressed compact and standing the pressed compact; or coating the dispersion liquid containing the carbonaceous powder on the surface of the powder compact, and then standing;

s3: sintering the carburized powder compact obtained in the step S2 at a high temperature to obtain a titanium product; wherein the maximum thickness of the hard layer in the titanium product is 1000 μm, and the hardness of the hard layer is controllable.

2. The method for producing a titanium product having a hardened layer of a titanium carbide-reinforced titanium-based composite material as claimed in claim 1, wherein the particle size of the titanium raw material is 10 to 60 mm.

3. The method of producing a titanium article having a hardened layer of a titanium carbide-reinforced titanium-based composite material according to claim 1, wherein in step S1, the near-net-shape forming technique is any one of a die pressing, a cold isostatic pressing and an injection molding process.

4. The method of claim 1, wherein in step S1, the relative density of the powder compact is 50-80%.

5. The method for producing a titanium product having a hardened layer of a titanium carbide-reinforced titanium-based composite material as claimed in claim 1, wherein in step S2, the carbonaceous powder is a fine carbonaceous powder; the fine carbonaceous powder includes carbon black powder, graphite powder, graphene, and carbon nanotubes.

6. The method for producing a titanium product having a hardened layer of a titanium carbide-reinforced titanium-based composite material as described in claim 1 or 5, wherein in step S2, the liquid medium of said dispersion is an organic solvent; the organic solvent is at least one of water, alcohol and acetone.

7. The method for producing a titanium product having a hardened layer of a titanium carbide-reinforced titanium-based composite material as claimed in claim 1, wherein the carbonaceous powder is contained in the dispersion in an amount of 0.5 to 20% by weight.

8. The method for preparing a titanium product with a hardened titanium carbide-based composite material layer according to claim 1, wherein in step S2, the soaking time is 1-5 min; the standing time is 2-3 h.

9. The method of claim 1, wherein the high temperature sintering is performed by an atmosphere sintering or vacuum sintering process; the sintering temperature is 1200-1350 ℃, and the sintering time is 2-5 h.

10. A titanium product having a hardened layer of a titanium carbide-reinforced titanium-based composite material, which is produced by the production method according to any one of claims 1 to 9, wherein:

the hard layer of the titanium product and the dissimilar titanium product are manufactured integrally, and the thickness of the hard layer is 30-1000 mu m.

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