Fabrication Of YAG Transparent Ceramic By Solid-state Reaction Method And Centrifugal Casting Of Nd: YAG

Laser ceramics has received continuous attention in recent years. The development of nanotechnology provides an effective way for further improvement of process and performance of laser ceramics. Yttrium aluminum garnet is one of the most important laser materials because of its good chemical stability and excellent optical properties. Compared with single crystal YAG, polycrystalline YAG ceramics has many advantages:short preparation cycle, low cost, high doping concentration without quenching and bigger size. At present, synthesis methods of YAG powders include solid reaction, sol-gel processing and precipitation method, among which solid reaction method is widely used for its high yield and simple process.YAG powders were synthesized through solid reaction method by using commercial nano-sized Y2O3 and Al2O3 powders. The process of solid state reaction and the preparation of stable slurry of the synthesized powders were investigated in this paper. The results indicated that YAG phase was obtained after calcination at 1300℃for 4 hours from commercial nano-sized Y2O3 and Al2O3 powder, being about 200～300℃lower than the conventional YAG formation temperature. The powder had an excellent formability after calcination at 1200℃for 4 hours, and the sintered body which sintered at 1700℃for 5 hours had a uniform microstructure with an average grain size of 9.62μm. The sintering additives accelerated the sintering densification process, refined the grains and improved the transparency of YAG ceramic. Compared withα-Al2O3,γ-Al2O3 is a better aluminum source for the formation of YAG powder.This article explore the process for centrifugal casting of Nd:YAG ceramics. The results of Zeta potential and sedimentation measurement revealed that the slurry was tend to coagulate near isoelectric point (near pH=3). The slurry had a high Zeta potential and a good stability at pH≥10. The addition of dispersant shifts the isoelectric point to the low pH range and the change range of Zeta potential getting bigger. Well-dispersed slurry was obtained when the range of dispersant changes from 0.05ml/g powder to 0.1ml/g powder. A good sample was obtained through centrifugal casting method when the solid content of the slurry is 75wt%, the content of dispersant is 0.05ml/g powder, the pH is 10 and the sintering temperature is 1700℃.