Study On Surface Modified Nano Zirconia Ceramics

The nano crystalline zirconia powders have been fabricated from inexpensive starting materials, using convenient technology and simple experimental facilities. Furthermore, the powders have been coated with carbon by liquid suspension method and arc discharge method. The carbon-coated powders have been sintered so as to investigate the affecting mechanism of coating on sintered bulk and sintering process.The zirconia powders fabricated by precipitation-gel method have good dispersivity and uniform grain size of about 10nm. The powders are successfully coated with carbon by liquid suspension of polyvinyl alcohol and dextrin. It was found that after coated with carbon, the powders have good dispersivity and uniform carbon coating layer. There are some weak chemical bonds on interface. The effect of two organic materials (polyvinyl alcohol and dextrin) on coating result has also been discussed. It is shown that the optimum ratio of organicmaterial and powders is 1 to 10 and polyvinyl alcohol is better than dextrin for carbon coating. The lattice of the powders before and after coating is unchanged and keeps tetragonal.The powders have also been successfully coated by arc discharge method. The grain size is about 5nm. Meanwhile, a part of powders have been reduced to zirconium. The effects of electric current and voltage have been studied. The possibility of zirconia reduced into zirconium was evaluated. The coating mechanism in arc discharge method has been investigated.The carbon-coated powders by liquid suspension method have been sintered. The bulk density is 5.788g/cm3 and grain size is about 80nm. It can be concluded that the surface coating can effectively prevent the grain growing during sintering process.