Titanium is a highly common material, and 99.9% of titanium sponge is pure. Titanium alloy products possess extremely stable physical and chemical characteristics. They are not absorbed by the human body, do not react chemically when in contact with drugs or bodily fluids, do not ionize, and do not react with the musculoskeletal system of the human body, which is why they are referred to as “biophile metal”. Due to its “biophile” quality, titanium is non-toxic and resistant to corrosion by secretions in the human body when sterilizing techniques are used. As a result, it is extensively utilized in the production of medical equipment as well as human hip, knee, shoulder, cranium, hypochondriac heart flap, and bone fixation clamps.

Titanium has become increasingly prevalent in addressing defects, wounds, and diseases of human hard tissues, which encompass all bones and teeth within the human torso. This usage emerged in the mid-20th century when medical metal materials based on titanium alloy showcased unique and impressive effects in the surgical implantation of human hard tissues and interventional treatments of human soft tissues. This includes treatments in cardiovascular and cerebrovascular systems, peripheral blood vessels, and non-vascular regions such as the liver, biliary tract, and urethra.

In China, the development, production, and application of titanium alloy materials for medical devices have been significant. This includes the creation of innovative products like titanium alloy artificial joints, dental implants, intravascular stents, and heart valves. These have had momentous impact and are considered revolutionary contributions to the medical field. Clinical treatments have evolved beyond basic repair and orthopedics to more complex “alternative” treatment of tissues and organs. These advances have greatly enhanced patient quality of life, enabling us to overcome many significant diseases that were once insurmountable.

1. Progress in Titanium Alloy Material Development

In the past five years, numerous domestic companies have emerged as manufacturers of implantable materials, including titanium and stainless steel. Titanium parts, such as femoral heads, hip joints, humeri, cranial plates, knee joints, elbow joints, shoulder joints, metacarpophalangeal joints, jawbones, heart membranes, kidney membranes, vascular expanders, clamps, prosthetics, and fixation screws, have been successfully implanted in humans with excellent results. These achievements have been highly praised and well-regarded within the medical community.

2. Classification and Characteristics of Biomedical Titanium Medical Materials

Biomedical titanium alloy materials refer to a specific category of functional structural materials used in biomedical engineering, primarily for the production and manufacturing of surgical implants and orthopedic devices. According to professional standards for surgical implants and orthopedic devices, titanium alloy materials can be classified under the “metal materials” category for “materials used in surgical implants.” Moreover, within the three major types of medical devices – non-active surgical implants, active surgical implants, and orthopedic devices – titanium alloys can serve as raw materials for cardiovascular implants, bone and joint replacements, bone fixation devices, spinal implants, orthopedic equipment, cardiac pacemakers and defibrillators, cochlear implants, neural stimulators, and other implantable products. Based on their microstructural classifications, biomedical titanium alloys can be divided into four major categories: alpha (α) titanium alloys (such as pure titanium series), alpha+beta (α+β) titanium alloys (such as Ti6Al4V), beta (β) titanium alloys (such as Ti12Mo6Zr2Fe), and TiNi shape memory titanium alloys. Compared to medical stainless steel and cobalt-based alloys, these materials exhibit characteristics such as low density, high specific strength, lower elastic modulus, corrosion resistance, ease of machining, and good biocompatibility.

 3. Research and development status of biomedical titanium materials

The development of biomedical titanium and its alloys can be divided into three eras: the first era is represented by pure titanium and Ti6Al4V, the second era is characterized by the new α+β alloys represented by Ti5Al2.5Fe and Ti6Al7Nb, and the third era focuses on the research and development of titanium alloys with better biocompatibility and lower elastic modulus, with the exploration of β-type titanium alloys being the most widespread.

1.1

The first generation of biomedical titanium represented by pure titanium and Ti6Al4V

Industrial pure titanium was the first titanium alloy to be applied in this field. Currently, the clinical experience with pure titanium implants is quite established. However, commercially pure titanium cannot provide the comprehensive mechanical properties required for load-bearing medical materials, such as low strength and poor wear resistance, which limits its application. Although cold working can increase the strength of pure titanium, it is still insufficient for practical needs. Therefore, people started to consider using titanium alloys. Ti6Al4V, with its excellent biocompatibility and good comprehensive mechanical properties, became the first titanium alloy to be introduced into the field of biomaterials and remains the most widely used titanium alloy in biomedical devices.

1.2

The second generation of new α+β alloys represented by Ti6Al7Nb and Ti5Al2.5Fe

Due to the potential toxicity of the element V in Ti6Al4V, in the mid-1980s, two new α+β-type medical titanium alloys, Ti5Al2.5Fe and Ti6Al7Nb, were developed in Europe. Ti6Al7Nb has mechanical properties similar to the well-accepted “all-purpose” Ti6Al4V alloy and was successfully developed in Switzerland in 1989. It is a safe and promising material for biomedical implants. Researchers and experts from different countries have conducted in-depth studies on this titanium alloy with the potential for safe and promising applications in various aspects.

4. Production status of titanium medical devices in China

Up to now, pure titanium and Ti6Al4V titanium alloy are still the largest and most widely used traditional main materials for surgical implants in the world, and their sales account for more than 80% of the entire biomedical titanium alloy market in the world. The varieties of titanium and titanium alloy processed materials for surgical implants currently produced in China involve sheet (thickness 0.8~25mm), bar, and wire (diameter 1~90mm), and the supply state can be cold rolled, hot processing, and annealing state. The titanium alloy processed materials specified in the new national standard GB/T13810-2007 adopt the requirements of ASTM F136-02a in terms of chemical composition, mechanical properties, and microstructure, but at the same time, additional technical requirements such as microstructure rating, section shrinkage, and ultrasonic inspection of plates and bars are also added. Although China’s national standard clearly stipulates that the microstructure rating type of Ti6Al4V titanium alloy should conform to the a+b biphase structure of A1~A9, most of the domestic titanium materials are coarse crystal A3~A5 structure, and the quality stability is poor. The microstructure of titanium imported from the United States can reach fine crystallization of A1~A3 structure, of which the diameter of 15mm below the small specifications of the bar can reach A1 level (maxed a, b phase grain size is less than 10μm), so it has excellent strength and toughness, corrosion resistance and mechanical cutting performance. This results in the processing of high-end medical device products such as artificial joints, dental implants, and spinal internal fixation systems in China, which still need to import a large number of high-quality Ti6Al4V titanium alloy materials from abroad, while domestic medical titanium materials mainly meet the needs of domestic low-end medical device products such as bone plates and bone screws. In 2008, China’s sponge titanium and titanium production ranked first and second in the world, titanium consumption has accounted for the second place in the world, becoming a titanium industrial power after Russia, the United States, and Japan, of which the United States and Russia titanium consumption is mainly for national defense military. And China, Japan mainly for industrial civil 2010 China for biomedicines and devices in the field of production and sales of medical pure titanium and TC4 titanium alloy material has reached 1084 tons, of which exports accounted for about 20%, China’s annual production of medical Ti6Al7Nb titanium alloy material hundreds of tons, but almost all exports abroad, domestic no practical applications.

Medical Titanium injection molding

The machinability of titanium is poor, resulting in expensive traditional machining methods and low efficiency, which significantly adds to the processing costs. Any titanium components that can be machined are typically straightforward in their design, and due to limitations in these machining processes, most can’t harness the maximum potential of the material. Under these circumstances, the titanium metal injection molding process is considered ideal for handling titanium. This process benefits from high raw material utilization rates and lower batch production costs. Titanium products created using an injection molding process, are lightweight with a high strength-to-weight ratio. They also have superior biocompatibility, excellent oxidation resistance, and a good degree of corrosion resistance. Their utility spans across diverse industries including aerospace, medicine, chemical, automotive, and everyday consumer products, showing great promise for extensive development.

Tags Titanium-metallurgy |  Titanium powder | MIM Titanium