| Bone damage, a large segment of bone loss has always been the difficulty of clinical medicine. Looking for meet the requirements of artificial bone substitute materials is becoming a hot spot of current research. Biological activity is the ability to chemically bond to bone and in vivo biological material produced is an important indicator of the biological material.Currently biomedical materials are divided into two types, they are the hydroxyapatite as representative of bio-ceramic materials and the titanium alloys as representative of the bio-metallic materials. The porous structure of hydroxyapatite ceramics provided connected 3D growth environment for the growth of osteoblasts, it can easy form a bone combination to the organism and has good biocompatibility.But hydroxyapatite may easily lose efficacy under physiological load, because it is so brittle. Titanium and titanium alloys in the biomedical metal materials have the closest elastic modulus as the human bones and its biomechanical compatibility is very good. But titanium and titanium alloy is a kind of inert material, the alloy substrate generally required activation. The ability to lead phosphate deposition of titanium surface is lousy, so that its biocompatibility needs to be strengthened. In view of this, we can lead the titanium substrate be wrapped with a layer of hydroxyapatite coating on its surface to manufacture a kind of composite substrate, then the implant material both have the biocompatible of hydroxyapatite and the excellent mechanical properties of titanium alloys.Currently biomedical materials are divided into two types, which are the hydroxyapatite as representative of bio-ceramic materials and the titanium alloys as representative of the bio-metallic materials. The porous structure of hydroxyapatite ceramics provide connected 3D growth environment for the growth of osteoblasts, it can easy form a bone combination to the organism and has a good biocompatibility. But hydroxyapatite may easily lose efficacy under physiological load for its brittle. Titanium and titanium alloys have the closest elastic modulus as the human bones and its biomechanical compatibility is verygood in the biomedical metal materials. But titanium and titanium alloy is a kind of inert material, the alloy substrate generally required activation. The ability to lead phosphate deposition of titanium surface is lousy, so that its biocompatibility needs to be strengthened. In this paper,the HA/TC4 composite matrix was prepared with biomimetic mineralization method which has the both of the advantages of these two materials, and the effect of several experimental factors on the morphology, the growth rate and the calcium-phosphorus ratio was studied, and the biological activity of the composite sample were characterized.All these can offer an important reference approach to the new generation of biological materials.The effects of different pretreatment methods on hydroxyapatite calcium phosphate coating morphology were studied in this paper by using comparative test method. The results showed that acid etching and alkaline heat treatment was good for the nucleation and growth of HA, for the microporous structure could be formed on the surface of TC4. By analyzing the change law of the PH value of the deposition solution and the formation mechanism of HA calcium phosphate coating, some conclusion which could play some guiding role on follow experiments was obtained. Such as, the conditions of coating growth could be measured by checking the replacement cycle of the deposition solution and the changes of PH value. The conclusion that the main component of HA calcium phosphate coating were HA and CHA was obtained by using the detection means of X-ray diffraction and FTIR analysis.The effects of deposition’s initial p H, incubation temperature and soaking time on the growth rate, morphology and the calcium-phosphorus ratio of the coating were studied. The results showed that when the initial p H value was about 7.4, the temperature was about 37 ℃; the effects of these experimental factors on the experimental indicators were not the same. For the morphology of the coating, the higher the initial p H value was, the more densed the coating was,the lower the uniformity was; the higher the developing temperature was, the more loosen the coating was; the longer the soak time was, the more bulky the grain was.Whether the biological materials have bone induction or not, the prerequisite is that the bone-like apatite can be spontaneously induced andformed on the surface in the human physiological environment. By disposing standard simulated body fluid, the environmental conditions of the human body were simulated in this paper. By means of vitro immersion test, the biological activity of HA/TC4 composite sample was verified. By detection means of SEM,XRD and EDS analysis, only 8 days time, the bone-like apatite could be successfully induced in HA/TC4 composite sample. By controlling the initial p H value of the deposition, the deposition time, incubation temperature to obtain different surface morphology of the coating. Results show: the grain size when the bath initial p H =7.4 is significantly larger than p H is 6.4、8.4.Then the grain size leads to an increase in the uniformity of size reduced.As the culture temperature, the grains become coarse, the growth speed, reducing the number of crystal grains, resulting in a coating of osteoporosis. The longer the soaking time,and further grow the grain size, the coating is relatively dense.According to the analysis of cracks on the coating crack, take two schemes on the coating was improved: the first is divided into multiple deposition and multiple drying process, in order to reduce the number and size of crack, the coating becomes more dense, but makes the coating of HA grain size distribution uniformity reduced, second is to use The three deposition three dry method preparation of coating, improve the compactness of the coating, reduce crack.moreover the mechanical property of the coating because of the increased density increased to some extent The mechanical properties of obtained coatings were also investigated by means mentioned above. The results show that the adhesion strength between coating and Ti-alloy substrate can reach to 13.41 MPa after heat treating, the thickness of coming falls into 30~40μm. The porosity of obtained coatings is in the range of 56%~76%. Using bionics mineralization methods, the coating has been more available for clinical application no matter from morphology, coating-thickness, porosity or bonding strength. |
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