CN101285136A - A kind of preparation method of porous titanium and porous titanium alloy - Google Patents

Abstract

The invention relates to a preparation method of porous titanium and porous titanium alloy, which is characterized in that the preparation steps are as follows: baking Ti powder or Ti alloy powder in an oven, performing sandblasting roughening on the surface of a flat substrate or a rod-shaped substrate. Treatment: Spray the Ti powder or Ti alloy powder prepared in step 1 on the above substrate by cold spraying method, and place the coating layer obtained in step 3 in a vacuum heat treatment furnace for heat treatment. The invention has the characteristics of simple process, short production cycle and low production cost. The porosity distribution of the porous titanium and the porous titanium alloy prepared by the method proposed by the invention is relatively uniform and controllable. The porosity of the porous titanium and porous titanium alloy prepared by the method of the invention can vary from 5% to 50%, and the strength can vary from 30 to 75MPa according to the porosity. The method has good controllability and high production efficiency, and is conducive to industrial application.

Description

A kind of preparation method of porous titanium and porous titanium alloy

technical field

The invention relates to a preparation method of porous titanium and porous titanium alloy, which adopts cold spray forming technology and cooperates with vacuum heat treatment to obtain the required porous material. Mainly suitable for biological materials, but also for structural materials in special cases.

Background technique

Metal foam or metal porous material is a new type of engineering material that integrates physical function and structure, which developed rapidly internationally in the late 1980s. It is a functional material with special properties such as good permeability, controllable pores and pore sizes, stable shape, high temperature resistance, thermal shock resistance, regeneration, and machinability. Metal porous materials are widely used in filtration, separation, noise reduction, gas distribution, catalysis, heat exchange and other processes in aviation, aerospace, atomic energy, petrochemical, metallurgy, machinery, medicine, environmental protection and other industries. In recent years, the demand for metal porous materials in various fields has greatly promoted their development. On the other hand, titanium and titanium alloys are widely used in aerospace, biology and other fields due to their good corrosion resistance, high specific strength, and excellent biocompatibility. In its biological application, the preparation of porous titanium and titanium alloy is a key problem to be solved, which also involves an important indicator of the quality of porous materials: the uniformity of pore size and shape. At present, the existing porous titanium preparation methods mainly include: sintering method and thermal spraying method. The sintering method is mainly to pile up titanium balls, short titanium fibers, titanium mesh or TiH ₂ on the titanium or titanium alloy substrate for sintering (US patent US4206516, Chinese patent 03810032.0), but the porous titanium prepared by this method is poorly bonded to the substrate. Fibers fall off easily. Thermal spraying is mainly used to prepare porous titanium coatings. In 1971, U.S. Patent US3605123 reported the preparation of porous titanium coating by plasma spraying _TiH2 , but the pore uniformity of the obtained coating was poor. In 1985, the US patent US4542539 prepared a gradient porous titanium coating by flame spraying, but the bonding strength of the coating was low, only 7MPa. Japan's Kobe Steel Company used vacuum plasma spraying to prepare a porous titanium coating with a porosity of 40-60%, an elastic modulus of 4.7GPa, and a compressive strength of 85MPa. Sulzer Calcitek successfully applied the porous titanium coating prepared by vacuum plasma spraying to dental implants, and obtained FDA certification in 1997 and entered the market. However, vacuum plasma spraying equipment is expensive, and there are still problems of poor uniformity of pores and poor connectivity of openings. Recent studies have shown [W.-Y.Li, et al., Ti and Ti-6Al-4V coatings by cold spraying and microstructure modification by heattreatment, Advanced Engineering Materials, 2007, 9(5), 418-423], cold Spraying can be used to prepare Ti and Ti alloy coatings, and the prepared coatings exhibit high porosity; after heat treatment of the prepared coatings, the bonding strength between the coatings and the substrate is improved. However, these preliminary studies only involve the preparation of thinner coatings, and there is no characterization of the properties of the prepared coatings. The spraying process and heat treatment process are single and lack of system.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a method for preparing porous titanium and porous titanium alloy. The porosity distribution of porous titanium and titanium alloy prepared by the method is relatively uniform and controllable, and the equipment and process Simple, short production cycle and low production cost.

Technical solutions

The basic idea of the present invention is: first, cold spray forming on the substrate to prepare titanium or titanium alloy coating layer, and then conduct vacuum heat treatment, one is to increase the bonding strength between deposited particles, and the other is to improve the pores and their distribution.

A method for preparing porous titanium and porous titanium alloy, characterized in that the preparation steps are as follows:

Step 1: Bake Ti powder or Ti alloy powder with a particle size ranging from 5 to 200 μm in an oven at 80 to 100° C. for 1 to 4 hours;

Step 2: performing sandblasting roughening pretreatment on the surface of the flat substrate or the surface of the rod substrate;

Step 3: Spray the Ti powder or Ti alloy powder prepared in Step 1 on the above substrate by cold spraying method, the powder feeding amount during spraying is: 10-100g/min; the thickness of the coating layer is: 100μm-50mm;

Step 4: Place the coating layer obtained in Step 3 for heat treatment in a vacuum heat treatment furnace. The vacuum degree of the vacuum chamber is required to be less than 10 ^-3 Pa; the holding temperature is 600-900° C.; the holding time is 1-8 hours.

When the substrate needs to be peeled off, the substrate should be peeled off before the heat treatment in Step 4.

The selection principle of the particle size of the Ti powder or Ti alloy powder is: when the porosity after spraying is required to be less than 20% to 40%, the powder with a particle size of 5-100 μm is selected; when the porosity after spraying is required to be greater than 40% , choose 100-200μm powder.

In the sandblasting pretreatment, -24 mesh sand grains are used for the titanium or titanium alloy substrate; -100 mesh sand grains are used for the substrate to be stripped.

Beneficial effect

The preparation method of porous titanium and porous titanium alloy proposed by the present invention has the characteristics of simple process, short production cycle and low production cost. The porosity distribution of the porous titanium and the porous titanium alloy prepared by the method proposed by the invention is relatively uniform and controllable. The porosity of the porous titanium and porous titanium alloy prepared by the method of the invention can vary from 5% to 50%, and the strength can vary from 30 to 75MPa according to the porosity. The method has good controllability and high production efficiency, and is conducive to industrial application.

Description of drawings

Fig. 1: It is the photograph of the original powder appearance involved in implementing the present invention, wherein (a) is Ti powder, particle size 11-45 μ m, (b) is Ti powder, particle size 45-160 μ m, (c) is Ti-6Al-4V Powder, particle size 11-63μm;

Figure 2: Light microscope photo of the cross-section of the porous material prepared by using the Ti powder in Figure 1(a), where (a) is the sprayed state, and (b) is the heat-treated state;

Figure 3: Light microscope photo of the cross-section of the porous material prepared by using the Ti powder in Figure 1(b), where (a) is the sprayed state, and (b) is the heat-treated state;

Figure 4: Light microscope photo of the cross-section of the porous material prepared by using the Ti-6Al-4V powder in Figure 1(c), where (a) is the sprayed state, and (b) is the heat-treated state;

Figure 5: Light micrograph of the cross-section of the porous Ti coating prepared on the Ti-6Al-4V substrate using the Ti powder shown in Figure 1(a), where (a) is sprayed and (b) is heat-treated.

Detailed ways

Now in conjunction with embodiment the present invention will be further described:

Implementation example 1:

Choose 11-45μm titanium powder. The substrate is a 45mm×30mm×4mm low-carbon steel plate, and the surface is roughened with -100 mesh alumina fine sand before spraying. The working gas of cold spraying is compressed air, the gas pressure at the inlet of the spray gun is 2.7MPa, and the gas temperature is 500-520°C; the powder feeding gas is argon, the pressure is 3.0MPa; the powder feeding rate is about 30g/min; the spraying distance is 30mm, and the moving speed of the spray gun is 150mm /s. The thickness of the coating layer is about 5mm. After spraying, the substrate is peeled off, and then vacuum heat treatment is carried out, the heat treatment temperature is 850°C, the heat preservation time is 4 hours, and then cooled to room temperature with the furnace. Observe the cross-sectional structure of the coating, as shown in Figure 2, the distribution of pores in the coating is relatively uniform. The average porosity of the sprayed state is about 11%, and the average porosity of the heat treatment state is about 15%. After heat treatment, the contact interface between particles in the coating achieves metallurgical bonding, and the bonding strength is significantly improved, from about 25MPa in the sprayed state to more than 75MPa in the heat treated state.

Implementation example 2:

Choose 45-160μm titanium powder. The substrate is a 45mm×30mm×4mm low-carbon steel plate, and the surface is roughened with -100 mesh alumina fine sand before spraying. The working gas of cold spraying is compressed air, the gas pressure at the inlet of the spray gun is 2.8MPa, and the gas temperature is about 550°C; the powder feeding gas is argon, the pressure is 3.1Mpa; the powder feeding rate is about 30g/min; the spraying distance is 30mm, and the moving speed of the spray gun is 150mm/ s. The thickness of the coating layer is about 5mm. After spraying, the substrate is peeled off, and then vacuum heat treatment is carried out, the heat treatment temperature is 850°C, the heat preservation time is 4 hours, and then cooled to room temperature with the furnace. Observe the cross-sectional structure of the coating, as shown in Figure 3, the distribution of pores in the coating is relatively uniform. The average porosity of the sprayed state is about 15%, and the average porosity of the heat treatment state is about 18%. After heat treatment, the contact interface between particles in the coating achieves metallurgical bonding, and the bonding strength is significantly improved, from about 18MPa in the sprayed state to more than 70MPa in the heat treated state.

Implementation example 3:

Choose 11-63μm Ti-6Al-4V powder. The substrate is a 45mm×30mm×4mm low-carbon steel plate, and the surface is roughened with -100 mesh alumina fine sand before spraying. The working gas for cold spraying is compressed air, the gas pressure at the inlet of the spray gun is 2.8MPa, and the gas temperature is about 550°C; the powder feeding gas is argon, the pressure is 3.1MPa; the powder feeding rate is about 30g/min; the spraying distance is 30mm, and the moving speed of the spray gun is 150mm/ s. The thickness of the coating layer is about 5mm. After spraying, the substrate is peeled off, and then vacuum heat treatment is carried out, the heat treatment temperature is 850°C, the heat preservation time is 4 hours, and then cooled to room temperature with the furnace. Observe the cross-sectional structure of the coating, as shown in Figure 4, the distribution of pores in the coating is relatively uniform. Because the titanium alloy has high strength and poor deformation ability, the porosity of the prepared coating is higher, the average porosity of the sprayed state is about 28%, and the average porosity of the heat treated state is about 38%. After heat treatment, the contact interface between particles in the coating achieves metallurgical bonding, and the bonding strength is significantly improved, from about 10MPa in the sprayed state to about 55MPa in the heat treated state.

Implementation example 4:

Choose 11-45μm titanium powder. The substrate is a disc-shaped sample of Ti-6Al-4V with a diameter of 25.4mm and a length of 10mm, and the surface is roughened with -24 mesh alumina fine sand before spraying. The working gas for cold spraying is compressed air, the gas pressure at the inlet of the spray gun is 3.0MPa, and the gas temperature is 500-520°C; the powder feeding gas is argon, the pressure is 3.3MPa; the powder feeding rate is about 30g/min; the spraying distance is 30mm, and the moving speed of the spray gun is 150mm /s. The thickness of the coating layer is about 0.7mm. Vacuum heat treatment is carried out directly after spraying, the heat treatment temperature is 800 ℃, the holding time is 4 hours, and then cooled to room temperature with the furnace. Observing the section structure of the coating, as shown in Figure 5, the distribution of pores within 300 μm of the surface layer of the coating is relatively uniform, and the porosity is relatively high. The coating is well bonded to the substrate. The average porosity of the sprayed state is about 7%, and the average porosity of the heat treated state is about 13%. After heat treatment, the contact interface between particles in the coating achieves metallurgical bonding, and the bonding strength is significantly improved, from about 25MPa in the sprayed state to more than 70MPa in the heat treated state.

When implementing the inventive method, the powder particle size and scope are selected according to required porosity and pore size etc., when requiring porosity to be less than 20%～40%, select particle size 5～100 μ m; When requiring porosity greater than 40%, select 100～ 200μm powder for spraying.

The type of matrix material is selected according to the type of matrix biological material required, so as to form porous titanium or porous titanium alloy. When independent porous titanium or porous titanium alloy materials are required, it is necessary to consider the peeling of the prepared coating layer. Just choose general industrial metal materials as the substrate, such as carbon steel, etc., and use mechanical hammering or mechanical processing to peel off the substrate after spraying .

The sandblasting pretreatment is also determined according to the application requirements. For titanium or titanium alloy substrates, it is required that the sandblasting roughening effect is good and the surface roughness is large, and -24 mesh sand particles are used; for the substrate surface that needs to be stripped, simple sandblasting treatment can be used. The surface roughness is small, using -100 mesh sand grains.

The preparation of the coating layer requires that the powder feeding amount during spraying be 10-100g/min.

Claims (4)

1. A method for preparing porous titanium and porous titanium alloy, characterized in that the preparation steps are as follows: Step 1: Bake Ti powder or Ti alloy powder with a particle size ranging from 5 to 200 μm in an oven at 80 to 100° C. for 1 to 4 hours; Step 2: performing sandblasting roughening pretreatment on the surface of the flat substrate or the surface of the rod substrate; Step 3: Spray the Ti powder or Ti alloy powder prepared in Step 1 on the above substrate by cold spraying method, the powder feeding amount during spraying is: 10-100g/min; the thickness of the coating layer is: 100μm-50mm; Step 4: Place the coating layer obtained in Step 3 for heat treatment in a vacuum heat treatment furnace. The vacuum degree of the vacuum chamber is required to be less than 10 ^-3 Pa; the holding temperature is 600-900° C.; the holding time is 1-8 hours. 2. The preparation method of porous titanium and porous titanium alloy according to claim 1, characterized in that: when the substrate needs to be peeled off, the substrate should be peeled off before the heat treatment in Step 4. 3. The preparation method of porous titanium and porous titanium alloy according to claim 1, characterized in that: the selection principle of the particle size of the Ti powder or Ti alloy powder is: when the porosity after spraying is required to be less than 20 When %~40%, choose powder with a particle size of 5~100μm; when the pores after spraying are required to be greater than 40%, choose powder with a particle size of 100~200μm. 4. The preparation method of porous titanium and porous titanium alloy according to claim 1 or 2, characterized in that: in the sandblasting pretreatment, -24 mesh sand particles are used for the titanium or titanium alloy substrate; Use -100 mesh sand.

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