Preparation method of porous titanium material
Technical Field
The invention relates to a preparation method of a porous titanium material, belonging to the field of materials.
Background
Titanium and titanium alloys have been widely used in medical surgery, particularly in the field of bone repair, due to their excellent corrosion resistance, biocompatibility, low density, high specific strength, and the like. However, the elastic modulus of common titanium and titanium alloy is not matched with natural bone, and the tensile strength, compressive strength and bending strength of the titanium and titanium alloy are much higher than those of human bone, and the load cannot be well transferred to adjacent bone tissues from the implant, so that a stress shielding phenomenon is generated, bone stress absorption occurs around the implant, and finally the implant is loosened and broken, and further application of the titanium and titanium alloy is limited. Therefore, the titanium and the titanium alloy are made into porous structures to obtain the elastic modulus similar to that of bones, and the titanium and titanium alloy porous structure has important significance for successfully applying the materials to the field of human body implants.
At present, the preparation methods of biomedical porous titanium materials mainly comprise a powder metallurgy method, a powder slurry foaming method and a gel injection molding method. The powder metallurgy method has simple production process, but the porosity is influenced by the powder size, the powder arch bridge phenomenon and the like, and the porosity is lower; the powder slurry foaming method uses urea, starch, sodium chloride, ammonium bicarbonate and the like as pore-forming agents, the pore-forming agents are difficult to completely remove, and the uniformity of pores is poor; the gel forming method can realize the preparation of large complex parts with high aperture ratio and high porosity, but has the problems of complex process, difficult thorough removal of gel and the like.
Disclosure of Invention
The invention aims to provide a preparation method of a porous titanium material, which overcomes the defects in the prior art.
The invention provides a preparation method of a porous titanium material, which comprises magnesium and TiCl4The raw material is prepared by a chemical vapor deposition method.
Further, the raw materials also comprise chlorides of the alloy elements.
TiCl4Is liquid at normal temperature as long as the chlorides of the alloy elements are in TiCl4Has a certain solubility, can be used as an alloy component to be added into TiCl4In the preparation method, the porous titanium material is prepared. Wherein the addition amount of the alloy element chloride is only required to ensure that the alloy element chloride is in TiCl4Can be dissolved, and can be properly adjusted according to the performance requirements of target materials in the aspects of porosity, compressive strength, elastic modulus and the like.
Preferably, the chloride of the alloy element is AlCl3、SiCl4、NbCl5Or MoCl5One or a mixture of two or more of them.
Further, the preparation method comprises the following steps:
a. preparation of magnesium vapour and TiCl separately4Steam, magnesium vapour obtained and TiCl4Respectively protecting the steam with protective gas for later use;
b. pre-coating a film: introducing TiCl into the reaction mould at the same time4Steam and magnesium steam are used for pre-coating the reaction mould;
c. material deposition: introducing TiCl into the reaction mould subjected to pre-coating4Steam and magnesium steam to obtain deposit;
d. and (3) sintering: taking out the deposit obtained in the step c, and sintering to obtain the porous titanium material;
or comprises the following steps:
preparing magnesium vapor, and protecting the obtained magnesium vapor with protective gas for later use;
II, preparing TiCl4With chlorides of alloying elementsProtecting the steam with protective gas for later use;
III, pre-coating: simultaneously introducing mixture steam and magnesium steam into the reaction mould, and pre-coating the reaction mould;
IV, material deposition: simultaneously introducing mixture steam and magnesium steam into the reaction mould subjected to pre-coating to obtain a deposit;
v, sintering: and taking out the deposit obtained in the step IV, and sintering to obtain the porous titanium material.
The order of steps I and II above can be interchanged.
Further, the magnesium vapor is obtained at the vacuum degree of 20-50 Pa and the temperature of 700-800 ℃.
Further preferably, the magnesium vapor is obtained at a vacuum degree of 20Pa and a temperature of 750 ℃.
Further, the raw material for preparing the magnesium vapor is metallic magnesium with the purity of 99.9%.
Further, the protective gas is argon or helium.
Further preferably, the purity of the argon gas is 99.9999%.
Further, TiCl4So that it is heated to a temperature above 136 ℃ to obtain TiCl4And (4) steam. TiCl is preferably used in the invention4Heating to 150 ℃ to prepare TiCl4And (4) steam.
Further, TiCl is reacted with4Heating the mixture and the chloride of the alloy element to be above the boiling point of the mixture to obtain the gas-phase TiCl mixed with the chloride of the alloy element4. When the chloride of the alloy element is AlCl3In this case, the present invention preferably heats to 150 ℃ to prepare a mixture vapor.
Further, the reaction mold is a closed container to prevent air from polluting the reaction mold.
Further, the reaction mold is made of stainless steel or carbon steel, preferably 20G material.
The material of the reaction mold will affect the impurity content in the porous titanium material prepared, for example, in the case of steel molds, the contact part of the porous titanium and the mold will contain higher content of Fe; in other words, the mold will contaminate the porous material, which therefore needs to be pre-coated.
Further, the reaction conditions of the pre-coating film are as follows: heating the reaction mold to 1020-1050 ℃, and pumping the vacuum degree in the mold to 100-1000 Pa, wherein TiCl is added4The single hour feeding amount of the steam or the mixture steam is 1-10% of the weight of the porous material, and TiCl is added4The one-hour feeding amount ratio of the steam or the mixture steam to the magnesium steam is (2-3): 1.
Further preferably, the reaction conditions of the pre-plating film are as follows: heating the reaction mould to 1050 deg.C, and vacuumizing to 100Pa, TiCl4The single hour feeding amount of the steam or the mixture steam is 1.75-2% of the weight of the porous material, and TiCl is added4The single hour charge ratio of vapor or mixture vapor to magnesium vapor was 7: 3.
Furthermore, the material adding amount is determined according to the size of the reaction mould during pre-coating, and the film layer completely covers the mould.
Further, the reaction conditions for the material deposition are: heating the reaction mold to 980-1020 ℃, wherein the vacuum degree in the mold is 100-1000 Pa and TiCl4The single hour feeding amount of the steam or the mixture steam is 1-10% of the weight of the porous material, and TiCl is added4The one-hour feeding amount ratio of the steam or the mixture steam to the magnesium steam is (2-3): 1.
Further preferably, the reaction conditions for the material deposition are: heating the reaction mould to 980 deg.C, vacuum degree in the mould is 100Pa, TiCl4The single hour feeding amount of the steam or the mixture steam is 1.75-2% of the weight of the porous material, and TiCl is added4The single hour charge ratio of vapor or mixture vapor to magnesium vapor was 7: 3.
The weight of the porous material is calculated by the volume of the mold and the density of the material.
The feed rate has an influence on the porosity of the porous material, and further, if the weight of the material is large, the feed rate is increased appropriately, or the time is long.
The sintering in the preparation process of the invention is aimed at obtaining Mg and MgCl2With Ti andand/or separating the alloy element materials.
Further, the sintering conditions are as follows: the sintering temperature is 900-1000 ℃, the vacuum degree is 0.1-1 Pa, and the sintering time is 5-8 h.
Further preferably, the sintering conditions are: the sintering temperature is 900 ℃, the vacuum degree is 0.1Pa, and the sintering time is 5 h.
Further, the chloride of the alloy element is AlCl3When in contact with AlCl3The content of the mixed vapor is 1-5 wt%.
Further preferably, the chloride of the alloy element is AlCl3When in contact with AlCl3The content in the vapor of the mixture was 5% by weight.
The invention provides a preparation method of a porous titanium material. The porous titanium material with high porosity and compressive strength and elastic modulus close to human skeleton can be prepared by the method, and the obtained material has a three-dimensional communication structure, is favorable for body fluid transmission, and is favorable for improving the mechanical compatibility and biocompatibility of the implant material and human tissues. More conveniently, the properties of the porous material in the aspects of porosity, compressive strength and the like can be adjusted by controlling the feeding speed of raw material steam, the type and the content of the alloy. The preparation method is simple to operate, does not need to add pore-forming agents and gelling agents, and is suitable for preparing the biomedical titanium material.
Drawings
FIG. 1 is a scanning electron microscope image of the titanium-aluminum alloy porous material prepared in example 1;
fig. 2 is an XRD diffraction pattern of the titanium-aluminum alloy porous material prepared in example 1.
Detailed Description
The raw materials and equipment used in the embodiment of the present invention are known products and obtained by purchasing commercially available products.
The invention provides a magnesium-TiCl composite material4A method for preparing a porous titanium material by a chemical vapor deposition method is used as a raw material.
At present, magnesium thermal method is mostly adopted to reduce TiCl in the industrial production of titanium and titanium alloy4To prepare seaAnd (5) titanium sponge. The production process takes liquid magnesium as a reaction raw material, the prepared titanium sponge has a compact structure and low porosity, can not be directly used as a biomedical material, and can be prepared into a titanium-based alloy material only by melting into liquid in an electric furnace and further processing.
However, the inventors have unexpectedly found that in the production of titanium sponge, gaseous magnesium is mixed with TiCl4And the chlorides of the alloy elements can react on the surface of the die, the generated solid product can be deposited to obtain a porous material with high porosity and compressive strength and elastic modulus close to human skeleton, and the obtained material has a three-dimensional communicated structure, is favorable for body fluid transmission and is favorable for improving the mechanical compatibility and biocompatibility of the implant material and human tissues. More conveniently, the properties of the porous material in the aspects of porosity, compressive strength and the like can be adjusted by controlling the feeding speed of raw material steam, the type and the content of the alloy. The method provided by the invention has huge application prospect when being used for preparing the biomedical titanium material.
Example 1 preparation of three-dimensional connected titanium-aluminum alloy porous Material by the method of the present invention
1. Putting metal magnesium with the purity of 99.9% into a vacuum container, controlling the vacuum degree to be 20Pa, controlling the temperature to be 750 ℃ to prepare magnesium vapor, and protecting the obtained magnesium vapor by using argon.
2. In a closed container filled with argon at normal temperature (20-35 ℃), adding AlCl3With TiCl4Mixing to prepare AlCl with the content of 5 wt%3Of TiCl (A) to (B)4(ii) a Mixing the prepared AlCl3Of TiCl (A) to (B)4Heating to 150 deg.C to obtain vapor.
3. Heating a closed reaction mold with a volume of 0.5L and a material of 20G to 1050 ℃, pumping the mold to a vacuum degree of 100Pa, and mixing AlCl3Of TiCl (A) to (B)4Steam and magnesium steam are added simultaneously at the speed of 35g/h and 15g/h respectively, and pre-coating is carried out on the reaction mould for 1 h.
4. Heating the reaction mould to 980 deg.C, vacuumizing to 100Pa, and mixing AlCl3Of TiCl (A) to (B)4The steam and the magnesium steam are respectively 35g/h and 15g/hWhen the mixture is introduced into a reaction mould, AlCl is mixed in the container3Of TiCl (A) to (B)4When the addition amount of the steam reaches 2Kg, stopping introducing the steam of the mixture, introducing argon into the reaction mold, and cooling the reaction mold to room temperature (15-25 ℃).
5. And (3) after the reaction mold is cooled to room temperature, taking out the material deposited on the pre-plated film, then putting the material into a vacuum sintering furnace, and sintering the material in vacuum at 900 ℃ and under the vacuum degree of 0.1Pa for 5 hours to obtain the three-dimensional communicated titanium-aluminum alloy porous material.
The purity of the argon used in the above preparation process was 99.9999%.
The scanning electron micrograph of the porous material is shown in figure 1, and the XRD diffraction spectrum is shown in figure 2. As can be seen from the figure, the titanium-aluminum alloy porous material prepared in the example 1 has a three-dimensional through hole structure.
In addition, the compressive strength, elastic modulus and porosity of the porous material were measured according to the following methods:
the compressive strength is carried out on a universal material testing machine to obtain a stress and strain curve, and the stress platform is the compressive strength. The elastic modulus is obtained by dividing the stress by the strain. The instrument model is as follows: DWD-3050 microcomputer controlled universal tester.
Porosity: the density of the titanium porous body was obtained by dividing the density of the porous body by the density of titanium, and the density of the titanium porous body was obtained by the drainage method, i.e., by immersing the titanium porous body in water, and the volume was determined and divided by the weight.
The porosity of the porous material is 81 percent, the compressive strength is 110MPa, and the elastic modulus is 3.3 GPa.
Example 2 preparation of three-dimensional connected pure titanium porous Material by the method of the present invention
1. Putting metal magnesium with the purity of 99.9% into a vacuum container, controlling the vacuum degree to be 20Pa, controlling the temperature to be 750 ℃ to prepare magnesium vapor, and protecting the obtained magnesium vapor by using argon.
2. Introducing argon into TiCl in a closed container at normal temperature (20-35℃)4Heating to 150 ℃ to prepare TiCl4And (4) steam.
3. A reaction mold with a volume of 0.5L and a material of 20G is usedHeating to 1050 deg.C, vacuumizing to 100Pa, and adding TiCl4Steam and magnesium steam are added simultaneously at the speed of 70g/h and 30g/h respectively, and pre-coating is carried out on the reaction mould for 1 h.
4. Heating the reaction mould to 980 deg.C, vacuumizing to 100Pa, and adding TiCl4The steam and the magnesium steam are respectively and simultaneously introduced into the reaction mould at 70g/h and 30g/h, when TiCl is in the container4When the steam addition reaches 3.5Kg, the TiCl is stopped4Introducing argon into the reaction mold, and cooling the reaction mold to room temperature (20-35 ℃).
5. And after the reaction mold is cooled to room temperature, taking out the material deposited on the pre-plated film, then putting the material into a vacuum sintering furnace, and sintering the material in vacuum at 900 ℃ and under the vacuum degree of 0.1Pa for 5 hours to obtain the three-dimensional communicated pure titanium porous material.
The purity of the argon used in the above preparation process was 99.9999%.
The compressive strength, elastic modulus and porosity of the porous material were measured in the same manner as in example 1.
The porosity of the porous material is measured to be 62 percent, the compressive strength is measured to be 98MPa, and the elastic modulus is measured to be 3.0 GPa.