On Biomedical Titanium Alloy Micro Arc Oxidation Ceramic Layer Preparation Process And Performance

In this paper, the exploratory research was made on micro-arc oxidation technology of medical titanium alloy in constant voltage mode. The micro-arc oxidation films were prepared in Ca(CH3COO)2.H2O-NaH2PO4solution. The thickness, morphology, roughness, elementary composition and phases of the ceramic layer in medical titanium alloy surface were analyzed with the effects of the electrical parameters(voltage, frequency, duty ratio, oxidation time); The wear resistance of ceramic layer was investigated by changing the electrical parameters(voltage, frequency,oxidation time) in Na2SiO3-Na2PO4solution; And the biological activity performance of MAO coatings was investigated by the simulated body fluid (SBF) test, the bioactive activity of ceramic layer was judged by surface morphology, elemental composition and phase structure of the ceramic layer after soaking with the effects of soaking time.The results show that voltage,frequency,duty ratio and oxidation time are influential to the growth of the ceramic layer. The thickness, pore diameter and roughness increase with the increasing voltage, the decreasing frequency, oxidation time and pulsed duty ratio. XRD analysis showed, the ceramic layer were mainly composed by Anatase TiO2and Rutile TiO2, With the voltage or frequency increasing, some Anatase TiO2traslated to Rutile TiO2while Oxidation time influenced for the phase structure of the ceramic layer very obvious, first, The diffraction peak intensity of Rutile TiO2increased,but with the extension of oxidation time, the diffraction peak of Anatase TiO2was higher than Rutile TiO2. And the duty ratio was not obvious effects on Anatase TiO2and Rutile TiO2. EDS analysis shows that the content of P,Ca element in ceramic layer increase with the increasing voltage, frequency or duty ratio. However, The extension of oxidation time was not obvious effects on the content of P, Ca element.The friction and wear test shows that the abrasion loss of the ceramic layer increased gradually with the increasing of voltage or oxidation time, And the growth of abrasion loss increased gradually. The abrasion loss of the ceramic layer decreased with the increasing of frequency, the decreasing of abrasion loss decreased gradually with the increasing of frequency. And the wear rate of ceramic layer decreased. At the same time, voltage, frequency, duty ratio and oxidation time are influential to the coefficient of friction, But all of the coefficient of friction of the ceramic layer were keeped around0.3under various influencing factors.The simulated body fluid test shows that the porous structure of the ceramic layer can induce the deposition of hydroxyapatite (HA) in simulated body fluid after Titanium alloy micro-arc oxidation. The biological activities of ceramic layer were improved with the extension of soaking time,and the quantity of the HA increased.