| Ti6Al4V(TC4)alloy has good mechanics performance and biological activity,but the release of Al ions and V ions of TC4 after implanting it to the human body for a long time is not good for health.Hydroxyapatite(HA),as the most popular biomedical materialsl,is widely used in various fields because of its good biological activity,but its poor mechanical properties limit the development in the field of biomedical materialsl.It is one of the hot researches in the field of biomedical materialsl by the surface modification technology to prepare a layer of HA on the TC4 alloy surface and combining the good mechanical properties of TC4 alloy with the good biological activity of HA.There are many studies on the biocompatibilityof coatings,but there are few studies on the poor mechanical properties of HA,and there are fewer studies on the mechanical properties of composite bioeoatings.Adopt sol-gel method prepared HA powders,with different process parameters(p H,crystallization temperature)HA powder was prepared,and phase composition and morphological were researched by X-ray diffraction(XRD)analyzer and scanning electron microscopy(SEM).Finally,the optimum process parameters of HA powder were determined.The T/HA composite coatings with different process parameters(pulse power,scanning speed and pulse width)were prepared by laser cladding on the surface of TC4.The surface morphology,micro-structure,micro-hardness and weight loss of the composite coatings were tested and analyzed by SEM,optical microscope,micro-hardness tester and drop test.The optimum process parameters for the preparation of T/HA composite coatings were determined.Subsequently,T/HT composite coatings with different Ti contents were prepared with the same parameters.The T/HT composite coating was compared with T/HA composite coating.Finally,the prepared T/HA and T/HT(HT is a composite powder of Ti and HA)composite coatings were evaluated biological activity in vitro,and the surface morphology,elemental composition and phase composition of T/HA and T/HT composite coatings were analyzed by SEM,EDS and XRD.The experimental results show that the spherical HA powder with high degree of crystallization,small particle size,uniform shape,smooth surface and beneficial absorption and utilization when the pH is 8 and the crystallization temperature is 600 ℃,The surface of the T/HA composite coating has the most smooth,the best flatness and the less cracks defects,the organization is the cell dendrites,the hardness of coating is the largest can reach 1440.3HV when the pulse pulse power is 1.5kw,the scanning speed is 1mm / s and the pulse width is 9ms;When the content of Ti in the Ti and HA composite powder is 30%,the surface of the T / HT composite coating is complete,and the micro-structure of the cladding zone is fine,and the hardness is about 1137.6HV.T/HA and T/HT composite coatings were found after 30 days of simulated body fluid culture,both of which could induce the emergence of rod-shaped nano-hydroxyapatite,but the latter growth more orderly,induced the formation of HA faster than the former,which greatly shortened the bioceramic HA in the human body compatible cycle;In short,preparing HT coating on TC4 surface by laser cladding technology to improve the HA coating mechanical properties of the problem is achievable. |
