Microstructure and Electrochemical Behavior of Laser Cladded HA Coating on Pure Titanium TA2

Hydroxyapatite （HA, Ca10（PO4）6（OH）2） coating was fabricated on pure Ti （TA2） by laser cladding technology. The phase structure, microstructure, microhardness and electrochemical behavior of the laser cladded HA coating in artificial body fluid were investigated. The results show that the HA coating is mainly composed of highly crystallized HA. A transitional layer between HA coating and Ti substrate is formed. Microhardness measurement shows the gradually increasing of microhardness from 150 HV at TA2 substrate to 600 HV at transitional layer, and followed by a decreasing to 400 HV at HA coated layer. Electrochemical corrosion tests show that the HA coating has higher open circuit potential , lower corrosion current density and corrosion rate in comparison to the TA2 substrate.

Effects of trace Ca/Sn addition on corrosion behaviors of biodegradable Mg-4Zn-0.2Mn alloy

The effects of alloying elements of Ca/Sn on corrosion behaviors of the as-cast Mg-4Zn-0.2Mn alloy were investigated by immersion tests and electrochemical methods.The results indicated that the average corrosion rate value of the Mg-4Zn-0.2Mn-Ca alloy was∼0.31 mm/year in Hank’s physiological solution for 40 days,and corrosion resistance increased for the specimens containing Ca element rather than that containing Sn because of the higher breakdown potential value,lower current density and deactivated corrosion rate,which was ascribed to a formation of the uniformly distributed Mg-Zn-Ca ternary phase.

Effect of glycine addition on the in-vitro corrosion behavior of AZ31 magnesium alloy in Hank’s solution

This study reports on the effect of the addition of Glycine to Hank’s solution on the in-vitro corrosion behavior of AZ31 magnesium(Mg)alloy at 37℃and a pH of 7.4 studied by using potentiodynamic polarization(PDP),hydrogen collecting techniques and electrochemical impedance spectroscopy(EIS)in combination with surface characterization techniques such as optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy analysis(XPS).The results reveal that adsorption of glycine initially subdues the dissolution of AZ31 Mg alloy while in long run it enhances the dissolution of the alloy due to the commencement of the chelation effect of glycine with Ca^(2+) released from hydroxyapatite.The chelation of glycine with Ca^(2+) induces the formation of cracks in the surface film which further promotes the dissolution of AZ31 Mg alloy thereby forming a porous corrosion products layer on the surface of the alloy.As a result,both the continuous dissolution of AZ31 magnesium alloy and the hydrogen evolution rate(HER)are enhanced with increasing the immersion time in Hank’s solution.