ABSTRACT
Objective@#To evaluate the influence of different heat treatments on the corrosion behavior of a new Pd-Ag-In-Ga alloy. @*Methods @#The corrosion of a new Pd-Ag-In-Ga alloy was tested according to ISO 10271：2001/cor.1:2005(E). Taken as comparison, a commercial high-palladium alloy (Spartan® Plus) was also employed in the study. For electrochemical corrosion test, the open-circuit potential (Eocp) and potentiodynamic polarization curve were recorded and then the electrochemical parameters, namely corrosion potential (Ecorr) and corrosion current density (Icorr) calculated. The surfaces of the specimens that before and after corrosion test were observed by scanning electron microscopy (SEM). @* Results @#Both of the high-palladium alloys had lower corrosion tendency and higher corrosion resistance by heat treatment in the ISO 10271 electrochemical corrosion test. For both alloys, heat treatment at 500 ℃ was found to be effective in improving the corrosion resistance as the best datas of electrochemical parameters (Eocp, Ecorr, Icorr) were detected among the four temperature groups. However, no evidence showed that there was significant difference in corrosion resistance between the two alloys. Comparison of surface morphology of the specimens before and after electrochemical experiments by SEM demonstrated that all groups of the two alloys were visible of pitting corrosion and crevice corrosion phenomenon that gradually became less with increasing heat treatment temperature. Horizontal comparing among the groups of the two alloys, no apparent differences in the distribution of pitting and crevice corrosion was found. @*Conclusin @#The variation in compositions of high-palladium alloys did not cause significant difference in corrosion behavior due to the identical palladium matrix. The similarity in corrosion behavior among the two high-palladium alloys might be attributed to the predominant palladium content.
ABSTRACT
Objective:To study the surface structure and antibacterial property of Ag-containing coating(AgCC)on casting cobalt chromium alloy(Co-Cr).Methods:Plasma spraying technique was adopted to prepare AgCC on Co-Cr.Scanning electron microsco-py,energy dispersive analysis and X-ray diffraction analysis were used to evaluate the surface properties.The antibacterial effects of AgCC against staphylococcus aureus and candida albicans were examined by film attachment method.Fluorescence microscope was a-dopted to evaluate the bacteria adhesion property.Results:AgCC surface was uniform and compact,combined perfectly with sub-strate material.The content of the surface was mainly Ag,Cr and a small amount of Ag2 O and Cr2 O3 .The results of antibacterial as-say showed that on AgCC the number of bacterial colony was fewer(P<0.05)and bacterial adhesion was less than those on Co-Cr(P<0.05).Conclusion:AgCC surface was stable and has antibacterial property.
ABSTRACT
Objective:To observe the artifacts produced by dental metal crown made from different materials on magnetic resonance imaging (MRI).Methods:Mental crows made from Co-Gr,Ni-Gr,low-Ti alloy and Pure-Ti were respectively fabricated for upper right second premolar of a ripe crossbreed dog.The 4 different casting crowns were respectively put on experimental tooth and head MRI scan was carried out with 4 sequences of 1.5 T and 6 sequences of 3.0 T MRI respectively.The existence and extent of the arti-facts were assessed and compared.Results:On both 1.5 T and 3.0 T MRI,the Go-Gr alloy crown exhibited significantly wider arti-facts than the others (ANAVO analysis,P0.05).On 3.0 T MRI the artifacts produced by Ni-Gr was larger than that by low-Ti alloy or Pure-Ti(P0.05).By any of the test sequence either on 1.5 T or on 3.0 T,the Co-Gr alloy produced arti-facts in the most slices of MRI imaging and Pure-Ti in the least.Conclusion:Go-Gr alloy may produce larger artifacts than Ni-Gr, low-Ti alloy and Pure-Ti on MRI.