Study Of Prescription And Sintering Process On Machinable Dental Ceramics

It is generally accepted that ceramics exhibit excellent biocompatibility and aesthetic characteristics, and along with the application of Computer Auxiliary Design/Computer Auxiliary Machining (CAD/CAM) in the dentistry restoration technology, ceramics restorable materials with machinability become the study focus. Feldspathic ceramics, zirconia ceramics and alumina ceramics are frequently used as machinable dental ceramics, but the major of feldspathic ceramics failure in clinic is brittle fracture, the sintering temperature of zirconia ceramics and alumina ceramics are high, the energy consume large, so their application in clinic are limited. In this study, alumina was used an additive to strengthen and toughen the feldspathic ceramics, so the flexural strength of feldspathic ceramics can be improved greatly; proper feldspathic was added to the zirconia and the alumina to reduce their sintering temperature.The prescription and the sintering technology of the three ceramics composition materials were identified by a lot of experiments. The influences of sintering technology to the machinability and the flexural strength were discussed. By means of XRD, SEM and metallographic analysis, the crystallizing procedure and structure of crystallite when sintered under different condition were investigated.The results revealed that the sintering temperature of feldspathic ceramics was increase with the increase of content of alumina, the best sintering temperature was 1200℃, and the relative density was 97.9%, when 20wt% alumina was added to feldspathic ceramics. The property of feldspathic ceramics can be improved by alumina, the abrasion reached the largest, when 20wt% alumina was added to feldspathic ceramics, and the flexural strength was increase with the increase of content of alumina.The sintering temperature of zirconia ceramics and alumina ceramics were decrease with the increase of content of feldspathic, the machinability of zirconia ceramics and alumina ceramics will be improved with the increase of content of feldspathic, but their flexural strength will decrease. The integrated property is best, when 5wt% feldspathic was added to zirconia ceramics. The sintering temperature of zirconia ceramics was 1450℃, the relative density was 90.1%, the number of abrasion was 0.027g with 4 minutes, the flexural strength was 310MPa; The integrated property is best, when 10wt% feldspathic was added to alumina ceramics. The sintering temperature of alumina ceramics was 1450℃, the relative density was 93.6%, the number of abrasion was 0.04g with 4 minutes, and the flexural strength was 235MPa.