Preparation method of titanium foams for cancellous bone

A technology of foamed titanium and cancellous bone, which is applied in the field of foamed titanium materials, can solve the problems of reducing the service life of titanium and titanium alloy implant materials, unfavorable bone tissue growth, and few researches, so as to avoid stress shielding and realize Long-term fixation and simple operation

Inactive Publication Date: 2013-07-17

CHONGQING UNIV

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AI-Extracted Technical Summary

Problems solved by technology

However, compared with human bone with a porous structure, titanium and titanium alloys face two problems as implant materials: (1) The Young’s modulus of titanium and titanium alloys does not match the modulus of bone, resulting in stress shielding ( The shunting phenomenon of the physiological stress of the bone by the fixing material is called the stress shielding of the bone by the fixing material); (2) The dense structure is not conducive to the growth of bone tissue, which reduces the service life of titanium and titanium alloy implant materials

For the first time, M. Bram et al. used powder metallurgy to add urea as a pore-forming agent to p...

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Method used

1) mixing of raw materials: choose titanium powder and granularity and mix in the acicular crystal urea granules of 225-420 μm to obtain preliminary mixture, wherein the ratio of mass and number of titanium powder and pore-forming agent is 46.6:53.4 ; The microscopic morphology of titanium powder and urea particles is shown in Figure 1. The titanium powder can be purchased directly from the market, and its surface and irregular shape can improve the strength of the green compact on the one hand and facilitate sintering on the other hand.

Its porosity of the open-cell foamed titanium prepared by the present embodiment is 71.4%, and its compressive strength and Young's modulus are respectively 10.6MPa and 0.32GPa, and the mechanical properties of the foamed titanium prepared by the present embodiment and The matching of human cancellous bone, especially the matching of modulus, can effectively avoid the occurrence of stress shielding. In addition, the connected pore structure is also conducive to the growth of new bone and the transportation of body fluids, which realizes the permanent fixation of the implanted material and improves the service life of the implanted material. Therefore, from the perspective of bionics, the titanium foam prepared in this example can be used as a potential substitute material for human cancellous bone.

What Fig. 6 shows is the microscopic appearance figure that foam titanium obtains under sc...

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Abstract

The invention relates to a preparation method of titanium foams for cancellous bone. The preparation method comprises the following steps of: (1) mixing raw materials, namely selecting a primary mixture which is obtained by uniformly mixing titanium powder and a pore forming agent in a grinding body, wherein the mass part ratio of the titanium powder to the pore forming agent is (42.8-48.2):(52.8-58.2); (2) carrying out one-direction pressing on the primary mixture by adopting a universal material testing machine to prepare a green pressing body, wherein the one-direction pressure is 200-250MPa, and the pressure holding time is 1 minute; and (3) putting the green pressing body into a vacuum carbon tube furnace, sintering the green pressing body for 2 hours at 1200-1300 DEG C in an argon protective atmosphere to ensure that the pore forming agent is removed, and finally cooling along with the furnace to obtain the titanium foams. According to the titanium foams prepared by using the preparation method, the Young modulus is matched with that of the cancellous bone of the human body, therefore the stress shielding phenomenon is effectively avoided, and an implant can be permanently fixed; and meanwhile, the titanium foams can be prevented from being oxidized as far as possible by adopting the argon protective atmosphere.

Technology Topic

Cancellous boneStress shielding +3

Image

Examples

Experimental program(4)

Example Embodiment

[0033] Example 1: See figure 2 , A method for preparing titanium foam for cancellous bone, including the following steps:

[0034] 1) Mixing of raw materials: select titanium powder and acicular crystal urea particles with a particle size of 225-420μm and mix to obtain a preliminary mixture, wherein the mass ratio of titanium powder and pore former is 46.6:53.4; titanium powder And the microscopic appearance of urea particles like figure 1 Shown. The titanium powder can be purchased directly from the market, and its surface and irregular shape can improve the strength of the green compact on the one hand, and promote sintering on the other hand.

[0035] 2) The preliminary mixture is unidirectionally pressed into a green compact using a 600KN universal material testing machine, and the green compact is pressed into a cylindrical shape, wherein the unidirectional pressure is 200 MPa and the pressure holding time is 1 min.

[0036] 3) The green compact is placed in a vacuum carbon tube furnace, sintered in an argon protective atmosphere at 1250°C for 2 hours to remove the pore former, and finally cooled with the furnace to obtain foamed titanium. The heat treatment process of the green compact such as image 3 Shown from image 3 It can be seen that the use of vacuum to remove urea is beneficial to discharge the gas after urea removal from the furnace body, and sintering under an argon protective atmosphere can prevent the sample from being oxidized.

[0037] Figure 4 Shown are the thermal analysis results of urea granules, where curves 1 and 2 represent thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), respectively. It can be seen from the figure that urea, as a pore former, has been completely released at about 400°C, which can avoid contamination of the foamed titanium. From Figure 5 It is the XRD pattern of titanium powder and titanium foam after urea removal, from Figure 5 It can be seen that the characteristic peaks of the raw material titanium powder of the foamed titanium holder after urea removal indicate that the foamed titanium is not contaminated during the urea removal process.

[0038] Image 6 Shown is the micro-topography of the titanium foam obtained under the scanning electron microscope. From Image 6 (A) is the microscopic morphology of titanium foam at 100 times. From the figure, it can be clearly seen that the pores in the titanium foam are connected together and evenly distributed, which is very similar to the porous structure of human cancellous bone. Image 6 (B) is the microscopic image of the foamed titanium obtained at 500 times. It can be seen from the figure that the sintered neck of the foamed titanium is smooth and round and grows well. This shows that the titanium powder sintered at 1250°C for 2 hours has completed the rearrangement between the particles and formed the sintering neck. In addition, it was also found that there are single microscopic pores between the sintering necks, the size of which is between a few microns to a dozen microns. The presence of microscopic pores further increases the connectivity of the porous structure.

[0039] Figure 7 Shown is the stress-strain curve of titanium foam. The mechanical properties of foam metal mainly include compressive strength and Young's modulus. According to literature reports, the compressive strength of human cancellous bone is between 4-12 MPa, and the Young's modulus is 0.02-0.5 GPa. The compressive strength of the titanium foam prepared in this example is 10.6 MPa, and the Young's modulus is 0.32 GPa.

[0040] The open-celled titanium foam prepared in this example has a porosity of 71.4%, and its compressive strength and Young's modulus are 10.6 MPa and 0.32 GPa, respectively. The mechanical properties of the foamed titanium prepared in this example are comparable to that of the human body. The matching of bone, especially the matching of modulus, can effectively avoid the phenomenon of stress shielding. In addition, the connected hole structure is also conducive to the growth of new bones and the transportation of body fluids, which realizes the permanent fixation of the implant material and improves the service life of the implant material. Therefore, from the perspective of bionics, the foamed titanium prepared in this embodiment can be used as a potential substitute material for human cancellous bone.

Example Embodiment

[0041] Example 2: A method for preparing titanium foam for cancellous bone includes the following steps:

[0042] 1) Mixing of raw materials: select titanium powder and needle-shaped crystalline urea particles with a particle size of 225-420μm and mix to obtain a preliminary mixture, wherein the mass ratio of titanium powder and pore former is 42.8:58.2;

[0043] 2) The preliminary mixture is unidirectionally pressed into a green compact using a 600KN universal material testing machine, and the green compact is pressed into a cylindrical shape, wherein the unidirectional pressure is 200 MPa and the pressure holding time is 1 min.

[0044] 3) The green compact is placed in a vacuum carbon tube furnace, sintered in an argon protective atmosphere at 1250°C for 2 hours to remove the pore former, and finally cooled with the furnace to obtain foamed titanium.

[0045] The foamed titanium prepared in Example 2 has a porosity of 74.2%, a compressive strength of 6.3 MPa, and a Young's modulus of 0.15 GPa.

Example Embodiment

[0046] Example 3: A method for preparing titanium foam for cancellous bone includes the following steps:

[0047] 1) Mixing of raw materials: select titanium powder and acicular crystalline urea particles with a particle size of 225-420μm and mix to obtain a preliminary mixture. The mass ratio of titanium powder and pore former is 44.1:55.9;

[0048] 2) The preliminary mixture is unidirectionally pressed into a green compact using a 600KN universal material testing machine, and the green compact is pressed into a cylindrical shape with a unidirectional pressure of 250 MPa and a pressure holding time of 1 min.

[0049] 3) The green compact is placed in a vacuum carbon tube furnace, sintered in an argon protective atmosphere at 1300°C for 2 hours to remove the pore former, and finally cooled with the furnace to obtain foamed titanium.

[0050] The foamed titanium prepared in Example 3 has a porosity of 73.6%, a compressive strength of 8.3 MPa, and a Young's modulus of 0.25 GPa.

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PUM

Property	Measurement	Unit
Granularity	225.0 ~ 420.0	µm
Compressive strength	4.0 ~ 12.0	mPa
Young's modulus	0.02 ~ 0.5	GPa
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Avoid stress shielding
Short removal time

Preparation method of titanium foams for cancellous bone

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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