Abstract: With the vigorous development and major breakthroughs of biotechnology, the demand for biomedical titanium alloys is growing rapidly. However, due to the pathogenicity of V and Al in the widely used medical titanium alloys such as TC4 and TC4ELI, the research and development of new medical titanium alloys has great practical significance and broad market prospects in my country. This article briefly describes the classification, basic properties and application basis of biomedical titanium alloys; points out its development trend in the medical field; and summarizes the basic processing and preparation methods and performance evaluation methods of new β titanium alloys.
Keywords: medical titanium alloy; development; research progress; processing
Biomedical titanium alloy material refers specifically to a class of functional structural materials used in biomedical engineering, specifically refers to the production and manufacture of surgical implants and orthopedic devices [1]. The production and preparation of titanium alloy processing materials involves the fields of metallurgy, pressure processing, composite materials and chemicals, and is recognized as a high-tech product in the world. Titanium and titanium alloys have gradually entered the field of civilian consumption from the aerospace, aviation, national defense and military industries [2]. Products such as implants and medical equipment in the medical and health industry; titanium golf clubs in the sports and leisure industry, titanium spectacle frames, titanium watches, titanium bicycles and other products are increasingly in demand for titanium processed materials. With the vigorous development and major breakthroughs of biotechnology, the industry of biomedical metal materials and their products will develop into a pillar industry of the world economy [3]. Among them, titanium and its alloys rely on excellent comprehensive properties such as light weight, low elastic modulus, non-toxic, non-magnetic, corrosion resistance, high strength, and good toughness. In recent years, the demand for titanium and its alloys has also increased rapidly and steadily [4 ]. At the same time, as titanium alloys begin to enter plastic surgery and other fields, new potential market demands emerge, and the titanium alloy market will see faster growth in the future.
1 Research progress of medical titanium alloys
1.1 Classification of medical titanium alloys
Titanium alloys can be divided into three types according to the type of material microstructure: α-type, α+β-type and β-type titanium alloy.
1.2 The development trend of medical titanium alloys
According to literature survey [8-14], relevant research scholars at home and abroad agree that the development of medical titanium alloys has gone through three iconic stages. The first stage is represented by pure titanium and Ti-6Al-4V alloy; The second stage is a new type of α+β alloy represented by Ti-5A1-2.5Fe and Ti-6A1-7Nb; the third stage is mainly to develop and develop β-titanium with better biocompatibility and lower elastic modulus The stage of the alloy. The ideal biomedical titanium alloy material[15] must meet the following conditions: good biocompatibility, low modulus of elasticity, low density, good anti-corrosion performance, non-toxic, high yield strength, long fatigue life, and high temperature at room temperature. Great plasticity, easy forming, easy casting, etc. At present, the important alloys that have been widely used in implant materials are Ti-6A1-4V and Ti-6A1-4VELI. It has been reported in the literature [16-19] that V element can cause malignant tissue reactions and may have toxic side effects on the human body, while Al can cause osteoporosis and mental disorders; in order to solve this problem, current biomaterials scientists are committed to exploring Before researching new biomedical titanium alloy materials that do not contain V and Al, it is necessary to figure out what alloy elements are suitable for addition that are non-toxic and conform to the principle of biocompatibility. Studies [20-23] found that β titanium alloys containing molybdenum, niobium, tantalum, zirconium and other non-toxic elements contain a higher content of β stabilizing elements, and have a lower modulus of elasticity compared with α+β titanium alloys (E=55~80GPa) and better shear performance and toughness, more suitable for implantation into the human body as an implant.
2 Application of Titanium Alloy
2.1 Medical basis of titanium alloy
The main advantages of using titanium and titanium alloys as human implants are: (1) Density (20°C)=4.5g/cm3, light weight. Implanted in the human body: reduce the load on the human body, as a medical device: reduce the operational load of medical staff. (2) The modulus of elasticity is low, and pure titanium is 108500MPa. It is implanted in the human body: it is closer to the natural bone of the human body, which is conducive to bone connection and reduces the stress shielding effect of the bone on the implant. (3) Non-magnetic, not affected by electromagnetic fields and thunderstorms, which is beneficial to the safety of the human body after use. (4) Non-toxic, as an implant, it has no toxic and side effects to the human body. (5) Corrosion resistance (biologically inert metal material). It has excellent corrosion resistance in the immersion environment of human blood, ensuring good compatibility with human blood and cell tissue, and does not cause human body pollution as an implant. Allergic reactions will occur, which is the basic condition for the application of titanium and titanium alloys. (6) High strength and good toughness. Damage to bones and joints caused by trauma, tumors and other factors. In order to establish a stable bone scaffold, it is necessary to use curved plates, screws, artificial bones and joints, etc., and these implants should be left for a long time. The human body is subjected to the bending, twisting, squeezing, and muscle contraction forces of the human body, which requires the implant to have high strength and toughness.
2.2 The medical field and orthopedics field of titanium alloy
Market situation With the development of titanium alloys, the increase in the variety of titanium materials and the decrease in prices, the application of titanium in the civilian industry has increased exponentially. CFDA divides medical devices into three levels according to their safety from high to low, and is supervised and managed by three levels of government. Titanium and titanium alloy material implants belong to the third category of medical devices and are high-value consumables. . The sub-sectors that account for more than 5% of the market segment include in vitro diagnostics, cardiology, imaging diagnostics, orthopedics, ophthalmology, and plastic surgery. Among them, in vitro diagnostics, orthopedics and cardiac intervention are the fastest growing high-value consumables in China. The application of biomedical titanium and its alloy materials has gone through three iconic stages [27]: In the early 1950s, first in the United Kingdom and the United States, commercial pure titanium was used to make bone plates, screws, intramedullary nails and hip joints. . The Swiss company Mathys also uses Ti-6A1-7Nb alloy to manufacture non-reamed interlocking intramedullary nail systems (including tibia, humerus, and femur) and hollow screws for the treatment of femoral neck fractures. Porous Ni-Ti (PNT) alloy bioactive materials to manufacture cervical and lumbar intervertebral fusion cages (Cage) Canadian BIORTHEX company developed the use of porous Ni-Ti alloy patented material ACTIPORE to manufacture cervical and lumbar intervertebral fusion cages for the treatment of orthopedic spinal injuries. The new β-titanium alloy is an advanced material for orthopedics, dentistry, and vascular intervention, which accounts for 9% of the global medical device market share, and is still growing rapidly. The orthopedic medical device market is mainly divided into four areas: trauma, joints, spine and others. Among them, trauma is currently the only subdivision that is not occupied by foreign companies. The main reason is that the products in this field are low in technology, easy to imitate, and less difficult to operate. Many secondary and tertiary hospitals can perform it, and foreign companies cannot fully cover it. . Trauma products can be divided into internal fixation and external fixation devices. Internal fixation trauma products include intramedullary nails, bone plates and screws. In 2012, the domestic orthopedics market accounted for 34% of trauma, 28% of joints, 20% of spine, and others. 18%. Large joints are high-end medical devices with high technical barriers. At present, mainstream hospitals are mainly importing orthopedic materials. There is still a gap between domestic and imported products in terms of technology, design, research and development, materials, and surface treatment processes. . Artificial joints are mainly divided into artificial knee, hip, elbow, shoulder, finger, toe joints, etc. The most important joint replacements include hip and knee joints, which together exceed 95% of the global joint replacement market. Spinal implant devices include thoracolumbar spine plate system, cervical spine plate system and fusion cage system, among which the intervertebral fusion cage system is mainly used for the treatment of intervertebral disc replacement, and it is also the most important segment, accounting for about the entire spine implant market Half of it.
3 Conclusion
The superior performance of titanium alloy has achieved its leading position in the medical field. The material design and preparation technology of titanium alloy has been developed rapidly with the breakthrough of biotechnology and the massive demand for medical applications. The medical titanium alloys currently produced are mainly α+β type titanium alloys. From the perspective of the preparation process, the production of TC4 (TC4ELI) currently occupies a major market share. β-type titanium alloy has certain advantages in terms of biocompatibility and mechanical compatibility, so it has become a research hotspot of new medical titanium alloys and is the most promising technology in the field of medical implants. In the future, the production technology of titanium alloys should develop in the direction of low modulus, high strength, good biocompatibility and mechanical compatibility. From the perspective of development trends, β-type titanium alloys will become the direction of future development and the mainstream of the medical titanium alloy market.
