Fabrication Of Y₂O₃Transparent Ceramics By Using Colloidal Processing Method

Yttria is an important optical functional ceramic material. Because of its high melting point, high thermal conductivity, heat resistance, corrosion resistance, no birefringence, Yttria is the excellent high-temperature infrared materials and electronic materials. Colloidal casting can effectively control the agglomeration and impurities of the body, reduce defects, and form a variety of complex shape ceramic components. Centrifugal casting is one of the colloidal casting.Homogeneous precipitation method is used to prepare Y2O3spherical powders. The average particle size of Y2O3spherical powder precursor is about415nm. The average particle size is about400nm after sintering at1000℃. Different contents of the dispersant have a different impact on the stability of the slurry,when the dispersant is added with2wt%, the viscosity of the slurry is the lowest and the stability is good via sediemtaion and viscosity measurement.The fabrication of Y2O3transparent ceramics using colloidal processing method was reported. The optimum content of dispersant required for attaining stable suspensions was determined via sedimentaion and viscosity measurement. It is showed that the viscosity of the slurry gradually decreases with the increasing of the content of the dispersant. The viscosity of the slurry is the lowest when it is added with4wt%of ammonium polycarboxylate dispersant. The ceramics vacuum-sintered using compacts prepared from slurry added with4wt%of dispersant has the highest density,99.88%of theoretical density. Different types of dispersants have different effects to the slurry. When Tetramethyl ammonium hydroxide(TMAH) is added with2wt%and the ammonium polycarboxylate dispersant is added with3wt%, the viscosity of the slurry is lowest. The transmittance of the body with TMAH is higher than without TMAH after molding. The transmittance of body without TMAH is66%-73%at600-800nm, and for the body with TMAH, the transmittance is68%-74%at600-800nm. For the dispersant of2,3-dihydroxybenzoic acid, when is added with lwt%, the viscosity of the slurry is lowest.Rare-earth doped transparent Y2O3ceramic powders were fabricated by using colloidal casting from commercial Y2O3, Yb2O3, Nd2O3and Eu2O3powders. After vacuum sintering, the transmittance of the (Y0.95Eu0.05)203body is61-65%at600-800nm, the transmittance of the (Y0.99Ndo.oi)2O3body is60%at780nm, the transmittance of the (Y0.95Yb0.05)203body is65-72%at600-800nm. Luminescence properties of (Yo.95Euo.o5)203are studied.