Research On The Preparation And Properties Of Zn-HA/Mg Composites

Magnesium and its alloys are characterized by the density and Young’s modulusclose to human bone, the good mechanical properties and the excellent biologicalcorrosion characteristics, thus they are considered as a novel promising biodegradablebiomaterial. More important, magnesium has good biocompatibility with human bodybecause that the magnesium ion is the necessary element for human. However, it isbadly confined their application in clinical that the high corrosion degradation rateand the low mechanical properties of biological safety magnesium alloy. Zn-HA hasthe same crystal structure with HA. Numerous studies show that the Zn-HA added caneffectively improve the bioactivity and biocompatibility of HA. However, Zn-HA islimited as the application of bone substitute materials due to its low fatigue resistance,brittleness, and impact resistance. In this work, a Zn-HA/Mg composite was preparedby powder metallurgy process in order to develop a new biological compositematerial possessing the advantages of the both components. The mechanicalproperties and corrosion behavior of the Zn-HA/Mg composite were discussed bySEM TEM, XRD, EDS and FTIR were used to research the effect of the crystalstructure and the size of Zn-HA power with different Zn fraction.Ca（NO₃）₂·4H₂O and Zn（NO₃）₂·6H2O were used as raw materials. Thenano-powder of Zn-HA was synthesized by chemical precipitation method. Theresults show that the substitution of the Zn ions for the Ca ions caused the change oflattiee parameters of HA, furthermore, the substitution of the zine ions restrained thegrowth of Zn-HA crystal.Zn-HA composite were prepared using pure magnesium and Zn-HA powder withdifferent Zn fraction as raw materials. The effect Zn-HA powder with different Znfraction content on the corrosion and mechanical properties was studied. The mainconclusions were as the follow. Zn-HA increased corrosion resistance of theZn-HA/Mg composite. But the effect of Zn-HA power with different Zn fractioncontent on the corrosion resistance was non-linear, in this work; the Zn2-HA/Mgcomposite was of the optimal mechanical properties, corrosion resistance andbiological activity.The study of corrosion mechanism of the composites proves that micro electrochemical reaction in the composite material accelerated the corrosion ofmaterials, and the formation of corrosion pits. The Zn²⁺in the Zn-HA depositioninhibited the corrosion of the composites to some extent, leading to the decrease of thecorrosion. Mg（OH）₂deposited on the surface of as-immersed Zn-HA/Mg samples.