We synthesized a series of poly (glycerol, sebacate and lactic acid) (PGSL) with 1:1:0, 1:1:0.25, 1:1:0.5, 1:1:1mole ratio of glycerol, sebacate and lactic acid, in order to elucidate the relation of microstructure to thedegradation rate and mechanical properties. The microstructure of the polymer with lactic acid in the ratio of0.25 displayed phase separation structure. The crystallization temperature (Tc) and absolute crystallizationenthalpy (ΔHc) of PGSL tended to decrease with the increasing ratio of lactic acid. Degradation rate of PGSLwith lactic acid in the ratio of 0.25 was fastest in vitro and 35% mass loss occurred after 60 day degradation. Inthe range of 0, 0.5 and 1, the degradation rate decreased slightly with the lactic acid increasing and 18% massloss occurred after 60 day degradation when lactic acid was doped in the ratio of 1.0. All PGSL polymersinhibited platelet adhesion, prolonged whole blood clotting time, activated partial thromboplastin time andprothrombin time. In conclusion, doping lactic acid can modulate the microstructure of poly (glycerol,sebacate) (PGS), thereby control the degradation rate and mechanical property of PGS.

Zr-ZrC-ZrC/DLC gradient nano-composite films have been prepared on the NiTisubstrates by the technique of plasma immersion ion implantation and deposition (PIIID) combiningwith plasma-enhanced chemical vapor deposition (PECVD). The influence of C2H2 flow rate rangingfrom 30 sccm to 50 sccm on the chemical structure, microstructure, mechanical properties andcorrosion resistance of resulting thin films are investigated by Raman spectrum, XPS, XRD, frictioncoefficient test, nano-indentation, electrochemical corrosion test and atomic absorption spectrometry.XPS and XRD results indicate that on the outmost layer, the Zr ions are mixed with the DLC film andform ZrC phase, the binding energy of C 1s and the composition concentration of ZrC depend heavilyon the C2H2 flow rate. With the increase of C2H2 flow rate, the content of ZrC and the ratio of carbonsp3/sp2 decreases. The nano-indentation and friction experiments indicate that the gradient compositefilm at 30 sccm has a higher hardness and lower friction coefficient compared with that of the bareTiNi alloy. The microscratch curve tests indicate that Zr-ZrC-ZrC/DLC gradient composite filmshave an excellent bonding property with the substrate. Based on the electrochemical measurementand ion releasing tests, we have found that the Zr-ZrC-ZrC/DLC gradient composite films exhibitbetter corrosion resistance property and higher depression ability for the Ni ion releasing from theNiTi substrate in the Hank's solution at 37℃.

Dental diamond bur is now a regular rotary tool, with its head made of diamond particlesembedded into nickel coating, and its shank made of stainless steel. There are strong demands fromthe dentist on prolongation of usage life and avoiding of breakage. To solve this problem, on the onehand, since diamond is hard to be wetted under the condition of normal temperature and pressure dueto the high interfacial energy between diamond and general metals and alloys. Diamond particlescoated with titanium layer was used for the preparation of composite electroplating with the intentionof improving the interfacial adhesion between diamond and metal matrix; on the other hand,superelastic biomedical NiTi alloy was used as the substrate to improve the flexibility and prevent thebreakage. In this study, the optimal preparation parameters of Ni/surface-modified diamondelectroplating were determined by orthogonal test, and the bonding conditions between the diamondparticles and the NiTi alloy substrate were studied by scanning electron microscope. Furtherperformance comparison of Ni/modified and Ni/un-modified diamond composite electroplating wasconducted on a pin-on-disc wear machine under the dry sliding condition, and the material removalvolume was used as the evaluating criterion of wear resistance. The results showed that the bindingstrength between diamond particles and NiTi alloy substrate could be enhanced, as well as the wearresistance, which may give direction on the future design of dental bur.

Objectives. The purpose of this studywas to investigate the corrosion behavior of Ti-Ag alloysin artificial saliva solutions.Methods. The corrosion behavior of experimental Ti-Ag alloys in artificial saliva was examinedby means of potentiodynamic polarization measurements. The surface passive filmformedwas analyzed by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction(XRD) methods.Results. The alloyswere found to develop surface passive films after immersion for 1.8×103s. In comparison with commercially pure Ti, the Ti-Ag alloys exhibited better corrosionresistance with lower anodic current densities, larger polarization resistances, and higheropen-circuit potentials. The passive film formed was predominantly composed of TiO2, asdetermined by XPS. When fluoride ions were added in the solution, the TiO2 passive filmwas destroyed and Na2TiF6 was formed.Significance. Addition of Agwas found to be effective in reducing the corrosion current densityand increasing the open circuit potential of titanium in artificial saliva environment. Additionof fluoride ions in the solution severely reduced the corrosion resistance of Ti-Ag alloys.

With CP Ti sample as control, the electrochemical measurements were used to investigate the corrosionresistance of low modulus Ti16Nb shape memory alloy in Hank's solution with pH value 7.4. The OCP curvesshow that the passive film on the Ti16Nb alloy surface is quite stable. The tafel plots and anodic polarizationcurves prove that the Ti16Nb alloy has excellent anti-corrosion properties in Hank's solution, which is evenbetter than that of CP Ti. The XPS analysis reveals that the composition of the oxide film on Ti16Nb alloy ismainly TiO2 and Nb2O5. The indirect cytotoxicity results prove that Ti16Nb alloy has an excellentbiocompatibility as CP Ti with high proliferation rate approaching that of the negative control group.