CN109940162A - A kind of preparation method of carbide in-situ reinforced titanium and its alloy porous scaffold - Google Patents

Abstract

The invention discloses a preparation method of carbide in-situ reinforced titanium and its alloy porous support. Sucrose and graphene are added to a suspension containing a titanium source, mixed uniformly and then injected into a mold for freeze-drying and vacuum sintering, namely Porous scaffolds of carbide in situ reinforced titanium and its alloys can be obtained. The invention utilizes freeze-drying technology to control the distribution of sucrose and graphene in the pore wall, and in the process of vacuum sintering, the sucrose located on the inner wall of the pore and the graphene in the pore wall react with titanium in situ to generate enhanced phase titanium carbide. The amount added to control the generation of titanium carbide in the pore wall, so as to obtain titanium and its alloy brackets with high strength, good bonding between the matrix and the second phase, and impact resistance, which are widely used in aerospace, automobile manufacturing, biomedicine and other fields. prospect.

Description

A kind of preparation method of carbide in-situ reinforced titanium and its alloy porous scaffold

technical field

The invention belongs to the technical field of material preparation, and relates to a preparation method of carbide in-situ reinforced titanium and its alloy porous support.

Background technique

With the advancement of the new technology revolution, traditional titanium and titanium alloys have become increasingly difficult to meet the requirements of high technology. Titanium matrix composite material refers to a kind of composite material in which reinforcement is introduced into titanium or titanium alloy. It has both the ductility and toughness of the matrix and the high strength and high modulus of the reinforcement, so as to obtain higher specific strength, specific stiffness and high temperature resistance than titanium or titanium alloys, and has excellent designability. Therefore, in recent years It has been paid more and more attention by researchers at home and abroad.

Particle-reinforced titanium matrix composites are widely used in aerospace, automobile manufacturing and biomedicine due to their excellent properties such as high specific strength, high elastic modulus, good wear resistance and high temperature creep resistance. Titanium carbide has a small thermal expansion coefficient, high hardness, good thermal stability, low friction coefficient, and a similar density to titanium alloys, which can be used as a titanium matrix composite reinforcement. Aiming at the low bonding strength of the micro interface, the in-situ reaction method is a feasible method to improve the bonding strength of the reinforcement/matrix interface. Therefore, it is of great significance to use in-situ reaction to generate titanium carbide particles to enhance the strength and stiffness of titanium alloy scaffolds.

The patent "A method for low-cost industrial production of TiC particle-reinforced titanium matrix composites" (application number: 201711437226.8, publication date: 2018-06-22, publication number: 108193064A) discloses a low-cost industrial production of TiC particle-reinforced titanium matrix The method of composite material integrates the process of producing titanium powder by hydrogenation and dehydrogenation and the adding process of the reinforcing phase of the composite material, and integrates the production of TiC particle reinforced titanium-based composite material, so that the distribution of the reinforcing phase of the material is uniform, which has a certain effect on the strength improvement. However, its stiffness is not enough and its impact resistance is insufficient.

The patent "A preparation method of TiB-enhanced medical porous titanium" (application number: 201811528721.4, publication date: 2019-02-15, publication number: 109332700A) discloses a preparation method of TiB-enhanced medical porous titanium. TiB ₂ powder and pore-forming agent NH ₄ HCO ₃ are weighed according to a certain ratio, then mixed uniformly under the protection of argon, and then vacuum sintered in a spark plasma sintering furnace, and finally a low elastic modulus is obtained after vacuum heat treatment , TiB with high strength and moderate porosity enhances medical porous titanium, but the reinforced phase TiB is unevenly distributed in the matrix.

The patent "Preparation Method of In-situ Synthesis of Titanium Carbide Reinforced Titanium-based Porous Materials" (application number: 201410372169.X, publication date: 2015-12-09, publication number: 104141063B discloses an in-situ synthesis of titanium carbide reinforced titanium The preparation method of base porous material, which adopts powder metallurgy pore former technology, uses urea, carbon powder and titanium powder to prepare porous titanium base composite material with high strength and good corrosion resistance through batching mixing, pressing molding and sintering treatment steps , but its impact resistance is insufficient.

The document "Particulate reinforced titanium alloy composites economically formed by combined cold and hot isostatic pressing", (1993 "Industrial Heating" Vol. 60, pp. 32-37), uses a composite method to artificially add reinforced particles such as TiC to titanium alloys, It is prepared by external addition method, but this method cannot fundamentally solve the problems of uniform distribution of reinforcements and complete combination of reinforcements and matrix, and the contamination of external reinforcements will also reduce the performance of the material.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of carbide in-situ reinforced titanium and its alloy porous support, which solves the problems of poor interface bonding between titanium and its alloy porous support reinforcement and matrix, low strength and impact resistance existing in the prior art. The problem of insufficient performance.

The technical scheme adopted in the present invention is, a preparation method of carbide in-situ reinforced titanium and its alloy porous support, adding sucrose and graphene to a suspension containing a titanium source, mixing uniformly and then injecting into a mold, and freezing after freezing. After drying and vacuum sintering, the porous scaffold of carbide in-situ reinforced titanium and its alloy can be obtained.

The specific steps are as follows:

Step 1, adding dispersant, binder and titanium source powder to the solvent in sequence, and uniformly mixing for 20-24 hours to obtain a suspension;

Step 2, adding sucrose to the suspension obtained in step 1, stirring evenly, then adding graphene, and grinding by ball milling for 12-24 hours to obtain a composite slurry;

In step 3, the composite slurry obtained in step 2 is injected into a mold, and directional freezing is performed on a cooling source. After the suspension is completely frozen, the suspension is taken out and dried in a low-pressure environment to obtain a stent preform;

Step 4, vacuum sintering the stent preform obtained in step 3 at a high temperature to obtain a carbide in-situ reinforced titanium and its alloy porous stent.

In step 1, the solvent is distilled water or distilled water-tert-butanol mixed solution, the titanium source powder is one of titanium hydride, pure titanium or titanium alloy, and the dispersant is sodium polyacrylate, methylene dinaphthalenesulfonic acid A kind of sodium, sodium dodecyl benzene sulfonate or polyvinyl pyrrolidone, and the binder is a kind of polyvinyl alcohol, hydroxymethyl cellulose, citric acid or polyvinyl butyral.

In step 1, the volume ratio of the titanium source powder to the solvent is 1:2 to 5, the mass of the dispersant accounts for 0.5% to 2% of the mass of the titanium source powder, and the mass of the binder accounts for the mass of the titanium source powder. 0.2% to 3%.

In step 2, the mass of sucrose accounts for 5%-20% of the mass of the titanium source powder, and the mass of graphene accounts for 0.5%-4% of the mass of the titanium source powder.

In step 3, the freezing temperature during directional freezing is -120°C to -30°C, the cooling rate is 5 to 15 μm/s, and the freezing time is 1.5 to 3 hours.

In step 3, the bottom of the mold is made of thermally conductive material, and the thermally conductive material is aluminum, copper or silver.

In step 3, the pressure of the low pressure environment is 10-100Pa.

In step 4, the sintering temperature is 1200°C to 1400°C, and the sintering time is 1.5 to 3 hours.

The beneficial effect of the present invention is that the distribution of sucrose and graphene in the pore wall is controlled by the freeze-drying technology, and the enhanced phase titanium carbide is generated by in-situ reaction during sintering, so as to obtain high strength, good bonding between the matrix and the second phase interface, and impact resistance. Titanium and its alloy stents have broad application prospects in aerospace, automobile manufacturing, biomedicine and other fields.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments.

The present invention provides a method for preparing a carbide in-situ reinforced titanium and its alloy porous support. Sucrose and graphene are added to a suspension containing a titanium source, mixed uniformly and then injected into a mold, freeze-dried and vacuum sintered to obtain In situ reinforced titanium and its alloy porous scaffolds with carbides.

The specific steps are as follows:

Step 1, adding dispersant, binder and titanium source powder to the solvent in sequence, and uniformly mixing for 20-24 hours to obtain a suspension;

Step 2, adding sucrose to the suspension obtained in step 1, stirring evenly, then adding graphene, and grinding by ball milling for 12-24 hours to obtain a composite slurry;

In step 3, the composite slurry obtained in step 2 is injected into a mold, and directional freezing is performed on a cooling source. After the suspension is completely frozen, the suspension is taken out and dried in a low-pressure environment to obtain a stent preform;

Step 4, vacuum sintering the stent preform obtained in step 3 at a high temperature to obtain a carbide in-situ reinforced titanium and its alloy porous stent.

In step 1, the solvent is distilled water or distilled water-tert-butanol mixed solution, the titanium source powder is one of titanium hydride, pure titanium or titanium alloy, and the dispersant is sodium polyacrylate, methylene dinaphthalenesulfonic acid A kind of sodium, sodium dodecyl benzene sulfonate or polyvinyl pyrrolidone, and the binder is a kind of polyvinyl alcohol, hydroxymethyl cellulose, citric acid or polyvinyl butyral.

In step 1, the volume ratio of the titanium source powder to the solvent is 1:2 to 5, the mass of the dispersant accounts for 0.5% to 2% of the mass of the titanium source powder, and the mass of the binder accounts for the mass of the titanium source powder. 0.2% to 3%.

In step 2, the mass of sucrose accounts for 5%-20% of the mass of the titanium source powder, and the mass of graphene accounts for 0.5%-4% of the mass of the titanium source powder.

In step 3, the freezing temperature during directional freezing is -120°C to -30°C, the cooling rate is 5 to 15 μm/s, and the freezing time is 1.5 to 3 hours.

In step 3, the bottom of the mold is made of thermally conductive material, and the thermally conductive material is aluminum, copper or silver.

In step 3, the pressure of the low pressure environment is 10-100Pa.

In step 4, the sintering temperature is 1200°C to 1400°C, and the sintering time is 1.5 to 3 hours.

The matrix in the present invention is a porous scaffold of titanium and its alloys, and the matrix is reinforced by in-situ reaction of titanium, graphene and sucrose to generate carbide-reinforced titanium carbide.

The present invention is a preparation method of carbide in-situ reinforced titanium and its alloy porous support. Sucrose and graphene are added to the solution and mixed uniformly to obtain a composite slurry. The directional freeze-drying technology is used to determine the concentration of sucrose at the tip of ice crystals during the freezing process. The sucrose is pushed to both sides of the ice crystal and is mainly distributed on the inner wall of the hole. After high-temperature vacuum sintering, a titanium carbide layer of a certain thickness is formed in situ on the inner wall of the titanium and its alloys. This layer has higher stiffness than the stent. The ability of the porous stent to resist deformation when subjected to impact load is increased, and the rupture consumes a lot of energy when overloaded to avoid instantaneous failure of the porous stent.

In addition, the added graphene is uniformly dispersed in the slurry, and the graphene is uniformly dispersed in the porous pore wall after directional freezing. After vacuum sintering, graphene reacts with titanium to form titanium carbide. The interface between the titanium carbide reinforcement and the matrix obtained by in-situ reaction is good. When under load, the titanium carbide particles can hinder the expansion of cracks or deflect them, and the crack paths are tortuous, consuming more fracture energy, thereby improving the strength of the material. .

Example 1

Add 0.348g sodium polyacrylate, 0.696g carboxymethyl cellulose and _34.8g TiH2 powder to 50g distilled water in sequence, the mass ratio of TiH2 powder and distilled water is ₁ :5, after fully mixing for 20h, then add 1.74g sucrose and 0.696g TiH2 powder _g graphene ball milled for 20h to obtain slurry, the TiH2 slurry was injected into a cylindrical mold with polyethylene sidewall and bottom as thermal conductive material, directional freezing on -30℃ ethanol liquid cold source for 3h, the cooling rate was 15μm/s , after being completely frozen, placed in a low pressure drying environment of 10pa to obtain a scaffold body, vacuum sintered at 1300 ℃, and sintered for 1.5h to obtain a carbide in-situ reinforced porous titanium scaffold.

Example 2

Add 1.804g sodium dodecyl benzene sulfonate, 0.1804g polyvinyl alcohol and 90.2g pure Ti powder in sequence to 40g distilled water. The mass ratio of pure Ti powder and distilled water is 1:2. After fully mixing for 22h, add 9.02g Sucrose and 0.451g graphene were ball-milled for 24 hours to obtain a slurry. The Ti slurry was injected into a cylindrical mold with a polyethylene sidewall and a thermally conductive material at the bottom, and was directionally frozen on a methanol liquid cold source at -60 °C for 1.5 hours. The cooling rate was 10μm/s, after being completely frozen, placed in a low-pressure drying environment of 40pa to obtain a scaffold mass, vacuum sintered at 1200 °C, and sintered for 2 hours to obtain a carbide in-situ reinforced porous titanium scaffold.

Example 3

1.414g of polyvinylpyrrolidone, 0.707g of polyvinyl butyral and 70.7g of Ti ₆ Al ₄ V powder were sequentially added to 50 g of distilled water/tert-butanol mixed solution, the mass of Ti ₆ Al ₄ V powder and distilled water/tert-butanol was The ratio is 1:4. After fully mixing for 24h, add 9.191g sucrose and 2.121g graphene ball milling for 22h to obtain slurry, and inject the Ti ₆ Al ₄ V slurry into a cylindrical mold whose sidewall is polyethylene and the bottom is a thermally conductive material. , in a liquid cold source mixed with liquid nitrogen and ethanol at -90 ℃ for 2 hours, and the cooling rate is 5 μm/s. After being completely frozen, it is placed in a low-pressure drying environment of 20 pa to obtain a stent body, which is vacuum sintered at 1200 ℃ and sintered. In 2.5h, a carbide in-situ reinforced porous titanium alloy scaffold was obtained.

Example 4

0.2825g of polyvinylpyrrolidone, 1.695g of citric acid and 56.5g of pure Ti powder were added to the 30g distilled water/tert-butanol mixed solution in turn. The mass ratio of the pure Ti powder and distilled water/tert-butanol was 1:3. , then add 11.3g sucrose and 2.26g graphene ball milling for 12h to obtain slurry, inject Ti ₆ Al ₄ V slurry into a cylindrical mold whose side wall is polyethylene and bottom is thermal conductive material, and liquid nitrogen and methanol at -120 ℃ The mixed liquid cold source was directionally frozen for 3 hours, and the cooling rate was 15 μm/s. After being completely frozen, it was placed in a low-pressure drying environment of 100 Pa to obtain a stent mass, which was sintered in vacuum at 1400 °C for 3 hours to obtain carbide in-situ reinforced porous titanium. Alloy bracket.

Table 1 shows the porosity and compressive strength of the porous scaffolds of in-situ reinforced titanium and its alloys prepared in Examples 1, 2, 3 and 4 of the present invention. Table 1 shows:

Table 1 Porosity and compressive strength of in-situ reinforced titanium

It can be seen from the table that by adding carbon source sucrose and graphene in situ reaction to generate reinforced titanium carbide, the compressive performance of porous scaffolds is significantly improved, and with the increase of sucrose content, the porosity increases slightly.

The invention utilizes the freeze-drying technology to control the distribution of sucrose and graphene in the pore wall, and in-situ reacts during sintering to generate enhanced phase titanium carbide, thereby obtaining titanium and its alloy bracket with high strength, good bonding between the matrix and the second phase interface, and impact resistance. , has a wide range of application prospects in aerospace, automobile manufacturing, biomedicine and other fields.

Claims (9)

1. a preparation method of carbide in-situ reinforced titanium and its alloy porous support, is characterized in that, in the suspension containing titanium source, add sucrose and graphene, after mixing, inject in mould, through freeze-drying, vacuum After sintering, the porous scaffold of carbide in-situ reinforced titanium and its alloys can be obtained. 2. the preparation method of a kind of carbide in-situ reinforced titanium and its alloy porous support according to claim 1, is characterized in that, is specifically implemented according to the following steps: Step 1, adding dispersant, binder and titanium source powder in sequence to the solvent, uniformly mixing for 20-24 hours, to obtain a suspension; Step 2, adding sucrose to the suspension obtained in step 1, stirring evenly, then adding graphene, and grinding by ball milling for 12-24 hours to obtain a composite slurry; In step 3, the composite slurry obtained in step 2 is injected into a mold, and directional freezing is performed on a cooling source. After the suspension is completely frozen, the suspension is taken out and dried in a low-pressure environment to obtain a stent preform; Step 4, vacuum sintering the stent preform obtained in step 3 at a high temperature to obtain a carbide in-situ reinforced titanium and its alloy porous stent. 3 . The method for preparing a carbide in-situ reinforced titanium and its alloy porous support according to claim 2 , wherein in the step 1, the solvent is distilled water or distilled water-tert-butanol mixed solution, and the The titanium source powder is one of titanium hydride, pure titanium or titanium alloy, and the dispersant is one of sodium polyacrylate, sodium methylene dinaphthalene sulfonate, sodium dodecylbenzenesulfonate or polyvinylpyrrolidone, The binder is one of polyvinyl alcohol, hydroxymethyl cellulose, citric acid or polyvinyl butyral. The method for preparing a carbide in-situ reinforced titanium and its alloy porous scaffold according to claim 2, wherein in the step 1, the volume ratio of the titanium source powder to the solvent is 1:2-5 , the mass of the dispersant accounts for 0.5% to 2% of the mass of the titanium source powder, and the mass of the binder accounts for 0.2% to 3% of the mass of the titanium source powder. 5 . The method for preparing a carbide in-situ reinforced titanium and its alloy porous scaffold according to claim 2 , wherein in the step 2, the mass of sucrose accounts for 5% to 20% of the mass of the titanium source powder. 6 . , the mass of graphene accounts for 0.5% to 4% of the mass of the titanium source powder. 6 . The method for preparing a carbide in-situ reinforced titanium and its alloy porous scaffold according to claim 2 , wherein in the step 3, the freezing temperature during directional freezing is -120° C. to -30° C. 7 . ℃, the cooling rate is 5～15μm/s, and the freezing time is 1.5～3h. 7. The method for preparing a carbide in-situ reinforced titanium and its alloy porous support according to claim 2, wherein in the step 3, the bottom of the mold is a thermally conductive material, and the thermally conductive material is aluminum, copper or silver. 8 . The method for preparing a carbide in-situ reinforced titanium and its alloy porous scaffold according to claim 2 , wherein, in the step 3, the pressure of the low-pressure environment is 10-100 Pa. 9 . 9 . The method for preparing a carbide in-situ reinforced titanium and its alloy porous support according to claim 2 , wherein in the step 4, the sintering temperature is 1200°C～1400°C, and the sintering time is 1.5～3h. 10 . .