Preparation And Performance Of The Al₂O₃ Film On Dental Materials

Stainless steel and Co-Cr alloy are current widely exploited in prosthodontical field.However, it is not in good taste because there is marked difference in colour between teethand stainless steel or Co-Cr alloy. The milk white and wear resistant oxide film wasobtained by the method of porcelain anodic oxidation after hot-dip aluminizing on thestainless steel and Co-Cr alloy first in this thesis. The hot-dip aluminizing condition fittingfor porcelain anodic oxidation was determined. The oxide film was analyzed by EDX andSEM. The forming process of the oxide film was discussed. The bonding force, thecorrosion resistance, the hardness and the porosity of the oxide film were measured and thecorrosion resistance of the oxide film in the NaCl electrolyte was analyzed.The results show that when hot-dip aluminizing on stainless steel and Co-Cr alloy, thethickness of the alloy layer and the total hot dip aluminum coating increased with theincrement of hot-dip time, had a maximum value with the increment of temperature andthe corresponding temperature was 750℃and 780℃.The hot-dip technologic parametersfitting for porcelain anodic oxidation were as follows: the hot-dip time was 5 minutes forboth stainless steel and Co-Cr alloy, the temperature was 710±5℃for the stainless steeland the temperature was 730±5℃for the Co-Cr alloy. The oxide film prepared under theoxidizing time was 50 minute, the current density was 0.8A/dm² and the electrolytetemperature was 50℃which was milk white with the luster of vitreous enamel, it wasAl₂O₃ by the analysis of EDX. The combination between the hot dip aluminum coating andthe stainless steel or Co-Cr alloy was metallurgical, the combination of the oxide film andthe hot dip aluminum coating was tested by WS-2000, the critical load was 76.2 N whenthe oxide film was peeled off from the hot dip aluminum coating. The corrosion ofporcelain anodic oxidation film sample was far better than the stainless steel and Co-Cralloy in the NaCl electrolyte. The microhardness of ceramic film was 600HV and the wearresistance was better than the stainless steel and Co-Cr alloy. There were 154.67 pores persquare centimeter.