Medical β titanium alloy production process
Used in domestic and foreign medical implants are mainly metal materials: 316, CoCr alloy, titanium and titanium alloys. Compared with the human bone elastic modulus, titanium and titanium alloy are the closest. Currently the most widely used commercially pure titanium and Ti-6Al-4V-based, and the new β alloy, due to have the most similar bone and elastic modulus, the current concern. The process design is:
1, alloy composition
In the design of titanium alloys, α-stable elements (Al, O, N, etc.) and β-stable elements (V, Mo, Nb, etc.) determine the classification of the alloy. Α alloys have only α phase; near α alloys contain a small amount of β stabilizing elements; α + β alloys contain higher β stabilizing elements; and β alloys have only β phases.
It is concluded that Nb. Zr, Mo and Ta are added as medical β titanium alloy. After being added to a definite content, the metastable β phase can be obtained by rapid cooling, which can effectively reduce the elastic modulus of the alloy. However, the addition of such alloying elements the amount cannot be too high, too high will lead to brittle ω phase precipitation, resulting in brittle alloy, elastic modulus increased. Therefore, a reasonable choice and control of the amount added is critical to obtaining the ideal low modulus. Typical are TNZ series alloys (including Ti-13Nb-13Zr, Ti-13Nb-20Zr, etc.).
2, heat treatment
In order to achieve the ideal β-phase structure, the β-type alloy should be rapidly cooled (such as water quenched) after the β-phase region is fully solution-treated. Induction medical β-phase alloy heat treatment is:
1) cold deformation of large deformation + hot deformation of annealing or large deformation (β-phase region or α + β two-phase region);
2) After the thermomechanical processing, the β-phase region is sufficiently solution-dissolved and rapidly cooled to obtain the whole β-structure as much as possible.
3, grain refinement
Grain refinement is an effective way to obtaining excellent mechanical properties of metallic materials. The advantages of medical implant β alloy grain after ultra fine treatment is as follows:
1) without changing the elastic modulus, improve the strength of the alloy, thereby enhancing the service life;
2) improve the wear resistance, reducing the implant alloy and bone and tissue contact wear and tear;
3) from the perspective of material processing and forming, the ultrafine-grained alloy has excellent plastic deformation ability, Superplasticity and good moldability.
The method used in the study is: Ultrafine Grained grains are obtained using the same diameter elbow extrusion method. In addition, there are also two-state microstructures of nano-scale matrix and micro-scale dendrite β phase obtained by the alloying method.
4, surface treatment
In addition to the strength and modulus properties of the alloy, surface wear resistance of medical implant materials has a significant impact on its service life, and poor wear resistance of the implanted alloy will lead to premature wear and failure. The method for improving the wear resistance of implant materials generally adopts surface coating. The traditional coating design mainly considers the biocompatibility, corrosion resistance and surface activity of the alloy, such as Al2O3, TiO2 coating and the like. In recent years, ion implantation, plasma spray coating, surface nitriding, surface carburization and other technologies to improve the surface hardness and wear resistance of the alloy. In particular, a diamond-like carbon coating has a significant impact on improving the wear resistance of the alloy.
In addition, the ultra fine treatment of the near-surface structure of the alloy to obtain submicron or nano-phase grains is also an effective way to improve the wear resistance and fatigue resistance of the material. Such as the use of induction heating quenching treatment, the use of induction heating "skin effect" can be realized near the surface of alloy instantaneous induction heating temperature.
Used in domestic and foreign medical implants are mainly metal materials: 316, CoCr alloy, titanium and titanium alloys. Compared with the human bone elastic modulus, titanium and titanium alloy are the closest. Currently the most widely used commercially pure titanium and Ti-6Al-4V-based, and the new β alloy, due to have the most similar bone and elastic modulus, the current concern. The process design is:
1, alloy composition
In the design of titanium alloys, α-stable elements (Al, O, N, etc.) and β-stable elements (V, Mo, Nb, etc.) determine the classification of the alloy. Α alloys have only α phase; near α alloys contain a small amount of β stabilizing elements; α + β alloys contain higher β stabilizing elements; and β alloys have only β phases.
It is concluded that Nb. Zr, Mo and Ta are added as medical β titanium alloy. After being added to a definite content, the metastable β phase can be obtained by rapid cooling, which can effectively reduce the elastic modulus of the alloy. However, the addition of such alloying elements the amount cannot be too high, too high will lead to brittle ω phase precipitation, resulting in brittle alloy, elastic modulus increased. Therefore, a reasonable choice and control of the amount added is critical to obtaining the ideal low modulus. Typical are TNZ series alloys (including Ti-13Nb-13Zr, Ti-13Nb-20Zr, etc.).
2, heat treatment
In order to achieve the ideal β-phase structure, the β-type alloy should be rapidly cooled (such as water quenched) after the β-phase region is fully solution-treated. Induction medical β-phase alloy heat treatment is:
1) cold deformation of large deformation + hot deformation of annealing or large deformation (β-phase region or α + β two-phase region);
2) After the thermomechanical processing, the β-phase region is sufficiently solution-dissolved and rapidly cooled to obtain the whole β-structure as much as possible.
3, grain refinement
Grain refinement is an effective way to obtaining excellent mechanical properties of metallic materials. The advantages of medical implant β alloy grain after ultra fine treatment is as follows:
1) without changing the elastic modulus, improve the strength of the alloy, thereby enhancing the service life;
2) improve the wear resistance, reducing the implant alloy and bone and tissue contact wear and tear;
3) from the perspective of material processing and forming, the ultrafine-grained alloy has excellent plastic deformation ability, Superplasticity and good moldability.
The method used in the study is: Ultrafine Grained grains are obtained using the same diameter elbow extrusion method. In addition, there are also two-state microstructures of nano-scale matrix and micro-scale dendrite β phase obtained by the alloying method.
4, surface treatment
In addition to the strength and modulus properties of the alloy, surface wear resistance of medical implant materials has a significant impact on its service life, and poor wear resistance of the implanted alloy will lead to premature wear and failure. The method for improving the wear resistance of implant materials generally adopts surface coating. The traditional coating design mainly considers the biocompatibility, corrosion resistance and surface activity of the alloy, such as Al2O3, TiO2 coating and the like. In recent years, ion implantation, plasma spray coating, surface nitriding, surface carburization and other technologies to improve the surface hardness and wear resistance of the alloy. In particular, a diamond-like carbon coating has a significant impact on improving the wear resistance of the alloy.
In addition, the ultra fine treatment of the near-surface structure of the alloy to obtain submicron or nano-phase grains is also an effective way to improve the wear resistance and fatigue resistance of the material. Such as the use of induction heating quenching treatment, the use of induction heating "skin effect" can be realized near the surface of alloy instantaneous induction heating temperature.
