Abstract：In order to improve the bioactivity of NiTi alloy and protect the human body from harming by Ni ion, the hydroxyapatite bioactive composite ceramic coatings was prepared by laser cladding on NiTi substrate in the present work. The structure evolution route of coatings affected by variation of the laser cladding parameters was researched by XRD,SEM,EDX and other analytic methods. And the bioactivity of coatings were assessed through the immersion of SBF solution. The main conclusions are stated as follows:
The HA/Ti composite coatings prepared by laser cladding formed a metallurgical bonding with the substrate. Besides the HA, the coatings also included CaO,CaTiO,and Ti-P compounds. The Ni element was remotely segregated in the HAZ zone and its bioactivity is turned out to be excellent. However, higher laser power would result in the decomposition of HA.
It's imperative for synthetic of HA coated by TiC>2 composite powders by heterogeneous nucleation to control the pH and the content of nucleation matrix HA. As the pH was approximately 8,and the ratio of the nucleation matrix HA with coated particles Ti〇2 was 1:2, the obtained HA/Ti02 composite powders owned a good quality.
The miniwatt fiber laser could be used to prepare the UAJT1O2 composite coatings,which was proved that it mainly consisted of HA,Ca2P2〇7,CaTiO〗,TiO and Ca3(PC>4)2.Compared with the composite coatings obtained by high-power laser(Nd:YAG), the favorable quality of light beam and sable output of laser power from miniwatt fiber laser are more beneficial for coatings shaping and to reduce the HAZ zone. What is more, it is also more suitable for manufacturing the composite coatings comprised of low-melting materials.
Key word: Laser cladding,Hydroxyapatite, Bioactive coatings, Bioacivity, Composites
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