Disclosure of Invention
Aiming at the problems that biomedical iron is slow in degradation and difficult to meet the requirement of bone tissue repair in the prior art, the invention provides an iron/sodium chloride bone implant. In the degradation process of the bone implant, the sodium chloride can release chloride ions and sodium ions, a porous structure is generated in an iron matrix, meanwhile, the released chloride ions have small radius and strong adsorption and penetration capacities, corrosion extension and penetration capacity are enhanced, an autocatalytic effect is generated, the chloride ions are main anions in body fluid of a human body and mainly responsible for controlling membrane potential and cell volume of cells in a resting stage, the effect of regulating and controlling glycine and gamma aminobutyric acid is also realized, the released sodium ions are main ions positively charged in extracellular fluid, and are involved in water metabolism to ensure balance of water in the body, and the effect of regulating myocardial meat and nerve work is involved, so that the bone implant has certain biosafety due to physiological effects of the sodium chloride.
In order to achieve the aim of accelerating iron degradation, the invention provides the following technical scheme:
An autocatalytically degradable porous iron-based bone implant is composed of an iron matrix and sodium chloride, wherein the mass percentage of the sodium chloride is 1.1-4.5 wt%.
Further, in the self-catalytic degradation porous iron-based bone implant, the mass percentage of the sodium chloride is 1.2-3.2 wt%.
Further, in the self-catalytically-degradable porous iron-based bone implant, the mass percentage of sodium chloride is 2.8wt.%.
Further, the granularity of the sodium chloride powder is 20-45 microns, and the size of the iron powder is 40-80 microns.
In the self-catalytic degradation porous iron-based bone implant, sodium chloride can be rapidly dissolved around, a plurality of uniformly distributed micro-pores are left, metal potentials around the micro-pores are negative and are in an activated state, metal potentials outside the micro-pores are positive and are in a passivation state, so that an active state, namely a passive micro-galvanic corrosion unit is formed inside and outside the micro-pores, the area of an anode (activated metal around the micro-pores) is smaller, the area of a cathode (passivated metal outside the micro-pores) is larger, a small anode and a large cathode phenomenon is generated, the current density of the anode is high, the anode is dissolved and aggravated, the corrosion has deep-digging expansion capacity, namely self-catalytic acceleration is carried out to the deep corrosion, and the micro corrosion with a plurality of tiny uniform distributions forms macroscopic rapid degradation.
Further, the density of the self-catalytic degradation porous iron-based bone implant is 85-95%.
Further, the density of the self-catalytic degradation porous iron-based bone implant is 87-93%.
The self-catalytic degradation porous iron-based bone implant is prepared by the following technical steps:
step one, mechanical mixing:
After drying the sodium chloride powder at constant temperature, weighing a certain mass, introducing the sodium chloride powder into iron powder for stirring for 3-5 minutes in 2-5 times in equal amount, and turning up and down in the stirring process to uniformly disperse the sodium chloride powder;
Step two, ball milling and dispersing:
After mechanical mixing, loading the mixed powder of the iron powder and the sodium chloride powder into a ball mill for ball milling and dispersing, wherein the ball material ratio is 7:1, the rotating speed of the ball mill is 150-220r/min, and in the ball milling and dispersing process, the ball mill is stopped for 3-5 minutes every 30-45 minutes to avoid overhigh heat generation caused by friction in a ball milling tank, and the ball milling time is 70-90 minutes;
Step three, electric spark sintering:
the mixed powder of the iron powder and the sodium chloride after ball milling and dispersing is solidified and molded by adopting an electric spark sintering process, wherein the sintering temperature is 550-850 ℃, the sintering pressure is 0.5-1.1kN, and the heat preservation time is 3-5 minutes;
Further, in the self-catalytic degradation porous iron-based bone implant, the rotating speed of the ball mill is 200r/min.
Further, in the self-catalytic degradation porous iron-based bone implant, the electric spark sintering temperature is 600-750 ℃.
Further, in the self-catalytic degradation porous iron-based bone implant, the spark sintering pressure is 0.7-1.1kN.
In the invention, the melting temperature of iron is higher than 1500 ℃ and the boiling point of sodium chloride is lower than 1500 ℃, so that sodium chloride volatilizes before the iron is fully melted, and in order to preserve sodium chloride to the greatest extent and avoid sodium chloride loss, the invention uses an electric spark sintering process, which can sinter and form at the temperature lower than the melting point of iron, ensures the chemical structure and the physical property of sodium chloride, and fully exerts the self-catalysis of the sodium chloride to accelerate the degradation of an iron matrix.
The electric spark sintering process can be used for rapidly forming the iron/sodium chloride bone implant, the rapid temperature rise limits the growth of crystal grains, the fine crystal strengthening effect is achieved, meanwhile, the iron/sodium chloride bone implant is extruded to a certain extent in the process of melting and solidification, the structural defects of micropores, cracks and the like in the conventional powder forming process are avoided, the structural integrity is improved, and the mechanical stability of the iron/sodium chloride bone implant in the degradation process is ensured.
The adopted electric spark sintering rapid prototyping iron/sodium chloride bone implant can shape a large-size massive compact sample at one time, the size and shape of the sample can be shaped according to a die, the subsequent treatment is convenient, and the requirement of the large-size complex structure bone implant is met.
After sodium chloride is added into the invention, the sodium chloride is firstly hydrolyzed into chloride ions and sodium ions, which can generate a plurality of micropores on the iron matrix, change the surface morphology, increase the surface area and cause local corrosion, and the large-scale local corrosion can show macroscopic corrosion on the whole, thereby accelerating the degradation of the iron matrix. More importantly, the released active chloride ions have small radius, strong capability of adsorbing and penetrating the iron base, and further penetrate the crystal lattice to generate crystal lattice defects, increase corrosion extension and expansion capability, and simultaneously, the released chloride ions can cause local conductivity enhancement, accelerate the separation of iron and electrons and increase the dissolution rate of an iron matrix.
The invention has the advantages that the content of sodium chloride needs to be strictly controlled, although chloride ions are common components in human bodies, chlorine is an ion with stronger corrosiveness, excessive addition amount can cause uneven mixing in an iron matrix, pitting or crevice corrosion at local positions is accelerated, and the integral fracture failure modes such as local corrosion deep holes and the like are generated, so that the steps of mechanical mixing and ball milling dispersion process of the iron/sodium chloride mixed powder are particularly important, including stirring time, ball milling time, ball material ratio and the like, and if the addition amount of sodium chloride is limited, the corrosion performance improvement effect of the iron matrix is limited, the micro and macro accelerated degradation effect is difficult to realize, therefore, the reasonable selection of powder proportion is needed, and in addition, the granularity of sodium chloride can influence the corrosion effect.
The electric spark sintering process has a great influence on the molding performance of the iron/sodium chloride bone implant, if the electric spark sintering temperature is low, mixed powder is difficult to be completely melted, powder particles are contained in a molded part to be soft, the molded sample has poor mechanical integrity, and if the electric spark sintering pressure is low, the compactness is greatly influenced, and the compactness is low.
Compared with the prior art, the invention has the following advantages:
(1) According to the invention, the iron/sodium chloride bone implant can be degraded gradually along with the repair of bone tissues, and the degradation process can be regulated and controlled by changing sodium chloride content, microstructure of the iron/sodium chloride bone implant and the like, so that the defect that inert biomedical metal is taken out by secondary operation in clinical application is overcome.
(2) In the invention, the iron matrix is degraded to produce substances such as iron-containing oxides, hydroxides and the like, can be phagocytized by phagocytes and the like or discharged outside the body along with metabolism, does not cause serious inflammation or toxicity, and has certain biological safety.
(3) In the invention, the sodium chloride can release chloride ions and sodium ions, the radius of the chloride ions is small, the capability of adsorbing and penetrating iron base is strong, the corrosion power is enhanced, and meanwhile, the chloride ions are main anions in body fluid of a human body, and the biological safety is realized.
(4) According to the invention, the preparation method of the iron/sodium chloride bone implant is simple and reliable, the mixed powder of iron and sodium chloride can be rapidly solidified by adopting electric spark sintering, the preparation time can be shortened, and the performance of a sintered body can be improved.
(5) In the invention, the sodium chloride has important application value in a plurality of aspects such as medicine and biology as a physiological solution, can induce actin monomers to polymerize, treat intestinal colic, supplement sodium salt and the like, and has low price at the same time, thereby meeting the requirement of an implant.
(6) According to the invention, the electric spark sintering rapid-forming iron/sodium chloride bone implant can simply form large-size massive compact samples, and the samples have good forming performance, are simple to operate, and are time-saving and labor-saving.
(7) In the invention, the electric spark sintered iron/sodium chloride bone implant is easy to form a porous structure after distilled water is used for cleaning and dissolving sodium chloride.
Detailed Description
Example 1
Weighing 2.8wt.% of sodium chloride, drying at constant temperature, introducing the sodium chloride with the average particle size of 30 micrometers into iron powder with the average particle size of 64 micrometers in 4 times of equal amount, stirring for 5 minutes, turning up and down in the stirring process, uniformly dispersing sodium chloride powder, mechanically mixing, loading the mixture of the iron powder and the sodium chloride powder into a ball mill for ball milling and dispersing, wherein the ball material ratio is 7:1, the rotating speed of the ball mill is 200r/min, and the ball milling time is 84 minutes every 40 minutes of running of the ball mill in the ball milling and dispersing process, and solidifying and molding the mixed powder of the iron powder and the sodium chloride after ball milling and dispersing by adopting an electric spark sintering process, wherein the sintering temperature is 710 ℃, the sintering pressure is 0.8kN, and the heat preservation time is 4 minutes;
The implementation effect is as follows:
The density of the iron/sodium chloride bone implant prepared by the method is 90% after the implant is washed in distilled water, the implant is quickly corroded in a soaking experiment and uniformly corroded, and the average corrosion depth is 24 microns after 5 days.
Example 2
Weighing 3.5wt.% of sodium chloride, drying at constant temperature, introducing the sodium chloride with the average particle size of 30 micrometers into iron powder with the average particle size of 64 micrometers in 5 times of equal amount, stirring for 5 minutes, turning up and down in the stirring process, uniformly dispersing sodium chloride powder, mechanically mixing, loading the mixture of the iron powder and the sodium chloride powder into a ball mill for ball milling and dispersing, wherein the ball material ratio is 7:1, the rotating speed of the ball mill is 220r/min, and the ball milling time is 90 minutes every 40 minutes of running of the ball mill in the ball milling and dispersing process, and solidifying and molding the mixed powder of the iron powder and the sodium chloride after ball milling and dispersing by adopting an electric spark sintering process, wherein the sintering temperature is 750 ℃, the sintering pressure is 1.0kN, and the heat preservation time is 4 minutes;
The method has the implementation effects that the density of the prepared iron/sodium chloride bone implant is 88% after being washed in distilled water, the iron/sodium chloride bone implant is fast and uniform in corrosion in a soaking experiment, and the average corrosion depth is 27 microns after 5 days.
Example 3
Weighing 1.2wt.% of sodium chloride, drying at constant temperature, introducing the sodium chloride with the average particle size of 30 micrometers into iron powder with the average particle size of 64 micrometers in 3 times in an equal amount, stirring for 5 minutes, turning up and down in the stirring process, uniformly dispersing the sodium chloride powder, mechanically mixing, loading the mixture of the iron powder and the sodium chloride powder into a ball mill for ball milling and dispersing, wherein the ball material ratio is 7:1, the rotating speed of the ball mill is 160r/min, and the ball milling time is 72 minutes every 40 minutes of running of the ball mill in the ball milling and dispersing process, and solidifying and molding the mixed powder of the iron powder and the sodium chloride after ball milling and dispersing by adopting an electric spark sintering process, wherein the sintering temperature is 730 ℃, the sintering pressure is 0.9kN, and the heat preservation time is 4 minutes;
The method has the implementation effects that the density of the prepared iron/sodium chloride bone implant is 94% after being washed in distilled water, the iron/sodium chloride bone implant is fast and uniform in corrosion in a soaking experiment, and the average corrosion depth is 15 microns after 5 days.
Example 4
Weighing 1.8wt.% of sodium chloride, drying at constant temperature, introducing the sodium chloride with the average particle size of 30 micrometers into iron powder with the average particle size of 64 micrometers in 3 times in an equal amount, stirring for 5 minutes, turning up and down in the stirring process, uniformly dispersing the sodium chloride powder, mechanically mixing, loading the mixture of the iron powder and the sodium chloride powder into a ball mill for ball milling and dispersing, wherein the ball material ratio is 7:1, the rotating speed of the ball mill is 170r/min, and the ball milling time is 78 minutes every 40 minutes of running the ball mill in the ball milling and dispersing process, and solidifying and molding the mixed powder of the iron powder and the sodium chloride after ball milling and dispersing by adopting an electric spark sintering process, wherein the sintering temperature is 750 ℃, the sintering pressure is 1.0kN, and the heat preservation time is 4 minutes;
the method has the implementation effects that the density of the prepared iron/sodium chloride bone implant is 92% after being washed in distilled water, the iron/sodium chloride bone implant is fast and uniform in corrosion in a soaking experiment, and the average corrosion depth is 17 microns after 5 days.
Comparative example 1
Other conditions are the same as those in example 1, except that sodium chloride powder and iron powder are mixed by stirring according to a mass ratio of 15:85 to obtain a degradable iron-based implant, the density is lower after distilled water is washed, the microscopic pores are unevenly distributed, the sample is transversely moved in the compression process after the block is compressed, which is probably caused by uneven stress in local areas, larger corrosion pits are found after soaking for 5 days, and the local corrosion phenomenon exists.
Comparative example 2
Other conditions are the same as those of the example 1, except that sodium chloride powder and iron powder are mixed according to the mass ratio of 0.3:99.5, so that the degradable iron-based implant is obtained, the compactness is higher and reaches 98% after testing, the integral molding performance of the sample is excellent, the corrosion is slower after soaking for 5 days, and the corrosion degree is close to that of pure iron.
Comparative example 3
Other conditions were consistent with example 2 except that the spark sintering temperature was 280 degrees, resulting in a degradable iron-based implant, which was tested to find that the overall molding properties of the test specimen were poor and did not have good mechanical integrity.
Comparative example 4
Other conditions are the same as those of example 1, except that the ball-to-material ratio is 3:1, the rotation speed of the ball mill is 80r/min, and the ball milling time is 20 minutes, so that the degradable iron-based implant is obtained, and serious local corrosion holes and uneven corrosion are found.
It can be seen from examples 1,2,3 and 4 and comparative examples 1,2,3 and 4 that the components and the preparation process of the present invention are an organic whole, and the effect thereof is significantly reduced when any one or several of the key parameters are not within the scope of the present invention. The preferred embodiment of the present invention has unexpected effects by the intrinsic comparison of the present invention in examples 1 and 2, and examples 3 and 4.