Research On The Pore Characteristics And Properties Of Porous Ti Alloy Biomaterials

Due to their similar elastic modulus to bone, excellent biocompatibility and mechanical properties and corrosion resistance in biological environment, titanium alloys have been widely studied and widely used in clinics. Along with requirement of biomaterials increasing in medical treatment, it is very important to develop and study novel titanium alloy in medical use. According to exploitation status quo and existing flaws of titanium alloys for surgical implants, considering the design principles and melting technology, new titanium alloys Ti-In for surgical implants is designed and studied, and also their mechanical properties and microstructures are systematically studied in this thesis.Choosing indium as strengthening element because it has many advantages, excellent corrosion stability and well biocompatibility when strengthening. This paper utilizes powder metallurgic method to manufacture titanium-indium alloy. The porous titanium produced by powder metallurgic method has not only characteristic of common metals porous materials but also less density,large specific strength,corrosion stability and well biocompatibility etc which are exclusive and excellent performance of titanium. Moreover, its production process is simple,cost is lower. We can control porosity and aperture of production and obtain porous titanium of organization structure equality.Experiment by metallography microscope and scanning electron microscope observed porosity, hole's shape,hole's distributing of porous titanium and microstructure of alloy; confirmed phase composition of titanium-indium alloy by X-ray; determined mechanical properties of the material by experiment of compressed and observed shape of fracture; checked corrosion stability of the material by simulating mouth environment in vitro and the experiment of electrochemical corrosion; progressed zoopery and examined toxicity of the material by inspecting standard of materials.The optic photos shown that after appending indium and pore-forming material, porosity of the material enhances, shape of holes becomes much more nodulizing, aperture is about 10-30μm, holes distributes much more equality. The reason is indium becomes liquid during cementing process, flowing onto titanium alloy surface, working holes in its original place. Yet pore-forming material becomes gas and works holes in its original place as well during cementing process. But porosity enhances at first and decreases last along with content of indium increasing. This status also appears when content of pore-forming material increasing. This may because when indium and pore-forming material are appended more much, shrinkage of alloy becomes larger during process of cooling. The material'porosity which is 10.3981% is maximum when 0.3% indium and 1% pore-forming material are appended; this componential alloy is most propitious to produce biomaterial. It is propitious to transplant of flesh new bone structure because of increase of holes. The result of metallography microstructure analysis and X-ray diffraction phase analysis shown that titanium of alloy isα-Ti which is obtained when slow cooling to 882.5℃after agglomeration thenβtransforms intoα. It just is the anticipant result.The result by analyzing compression stress-strain curve of lacunaris titanium alloy shown that: compressive strength of lacunaris titanium alloy is about 1380Mpa, Young's modulus (modulus of elasticity) is about 25GPa which is equivalent to flesh's and absolutely accord with Young's modulus of transplant, it is anticipant intent. The fracture of titanium alloy in the experiment has not only rupture of micropore conglomeration but also cleavage fracture. The section of micropore conglomeration distributes in extensiveness and cleavage fracture appears in subregion. The rupture of micropore conglomeration causes materials separation by nucleation of micropore growth and aggregation. Cleavage fracture appears in subregion may because the sample is　?titanium alloy which's crystal structure is solid matter hex and easily occurs twinning phenomenon. But cleavage crack meets long twinning during extension procedure, crack traverses twinning and expands along with twinning cleavage face then develops a step, the cleavage fracture is formed.In the experiment of electrochemical corrosion which using Ringer normal saline as etching solution, appending indium and pore-forming material component alloy are better than pure titanium in corrosion stability. And corrosion stability of the material gradually meliorates along with increasing content of indium and pore-forming material. The reason is that appending indium then indium flows onto alloy surface, developing compact oxide film, forming materials corrosion; yet appending pore-forming material causes holes of alloy increase and surface area augment, forming compact TiO2 oxide film, heightening corrosion stability of alloy. The experiment by animals also shown that: the material hasn't hormesis to organism, hasn't toxin and side effect, don't destroy cell of animals; hemolytic ratio of each sample is between 0.655%--0.876% which less than 5%, so the material is considered has no hemolytic activity; the cytotoxicity level is between 0-1, so the cytotoxicity of alloy is eligibility in the experiment.From above conclusion we can know, the porosity of material is maximum when component mixture ratio is 0.3% indium and 1% pore-forming material; at the same time, it is most propitious to repot of bone tissue and enhances the bond trength on interface of transplant and bone tissue. The corrosion stability of material is best when component mixture ratio is 0.5% indium and 1.2% pore-forming material. All alloy of titanium and indium has excellent corrosion stability because titanium and indium both have good corrosion resistant. The effect of different component mixture ratio to compressive strength,Young's modulus and biology solubility with each other of the material is not big. So we think, alloy is most befitting as dentistry transplant when component mixed ratio of the material is 0.3% indium and 1% pore-forming material.The alloy of titanium and indium has not been developed as biomaterials in medical domain. In this paper, we produced porous alloy of titanium and indium by powder metallurgic method and detected the structure and the performance of alloy in order to supply theory basis and experiment data for practical application of the alloy. As a new titanium alloy, Ti-In is in good accordance with the requirements of the alloy designing principle, possesses excellent microstructure and properties, so the application outlook is promising.