Abstract:

Objective:The purpose of this studywas to investigate effects of cryotreaton the corrosion resistance of SDA-II mediummelt- ing-point castable alloy.Methods:12 samples were divided into three groups, including the control group, the cryotreated group and the cryotreated&post-cryogenic treated group. The cryotreating process was firstly dropping the temperature from room tem- perature to-170ewith dropping rate 3e/min, maintaining-170efor 2hrs, and then returning to ambient temperature with an increasing rate of 1e/min. The post-cryogenic process was maintaining the samples in 300efor 1hr. Finally, all sampleswere subjected to the electrochemical potentiodynamic polarization after immersed in the artificial saliva (ISO/TR10271:1993(E), pH 6.8) for 24hrs at ambient temperature. The exposing area of each sample was 10 mm@10 mm. The electrochemical tests were carried out in the artificial saliva under 37e, with the scanning rate of 20 mV/min, starting potential -200 mV below OCP and stopping current 10-3A. The corrosion currents (Icorr), the pitting corrosion potentials (Eb) and the potentiodynamic polarization curves were observed using the 283 electrochemical corrosion measuring system automatically.Results:For SDA-II medium melt- ing-point castable alloy, cryotreat reduced corrosion rate of the alloy, buthad no effecton the pitting corrosion potential. As far as the post-cryogenic treatment, it didnct affect the corrosion resistance.Conclusion:The results suggested that cryotreatwas an ef- fective procedure in enhancing the corrosion resistance of SDA-II mediummelting-point castable alloy, and itmay be applicable in prosthetic dentistry.

Key words: cryotreat, medium melting-point castable alloy, corrosion resistance