Calculation Of Thermodynamics And Process Simulation Of Yag Ceramic Materials Via Combustion Synthesis Under Ultra-high Gravity Field

Because of the important situation in the laser field, the Yttrium Aluminum Garnet (YAG) transparent ceramics, one of the advanced ceramic materials, has becomed a research hotspot at home and abroad. However, the powder metallurgy technical has been always mainly preparation method of YAG for a long time, which has so many defects such as long preparation time, high production costs, disguarantee quality and so on. At the same time, the high melting point of ceramics leads to liquid difficultly filling and thick organization formatting after high temperature solidification. Thereforce, it is very difficulty to prepare for the YAG by costing technique.It is reported that the Al2O3 transparent ceramics had been succeed to prepare by a new method-Combustion Synthesis under Ultra-high Gravity Field in Technical Institute of Physics and Chemistry of CAS. Based on this successful fact, some researches such as thermodynamic and kinetic analysis, simulation and experimental test and so on are carried on the YAG transparent ceramic in this paper. The results are lied on as follow:First of all, the thermodynamic database of materials is established. Combining with the common thermodynamic principle and Visual Basic language, a SHS system thermodynamic data calculation computer program is so obtained. And then, its reliability is verified by many ways. According to the adiabatic temperature of many SHS sytems, the thermite reaction system of YAG preparation is optimized by computer calculating. The results showed that the Al/NiO/Y2O3 thermite is the most appropriate system for YAG ceramic preparation.Secondly, the static experimental results of combustion synthesis show that the raw agents'facts such as sizes of aluminium powder and compact density have certain effect on combustion velocity. Melt-casting under ultra-high gravity integrates the combustion synthesis with ultra-high gravity technology. The ultra-temperature metal/ceramic mixing-melts can be achieved by heat generated from thermite combustion reaction. The ceramic product is separated in the ultra-high centrifugal field. The further researches show that the defects in YAG ceramic such as content of metal particles, the amount of pores and a variety of lattice defects are closely related to the magnitude of gravity and the existence time of melt, which can affect the transparency of YAG ceramic.Finally, the temperature and stress distribution during the combustion synthesis under ultra-high gravity were simulated and then were verified by ANSYS finite element analysis software. The experimental results agree very well with the simulation ones, which indicated the high reliability of this method. Combining with the adiabatic temperature calculation and experiments verification, the rules of the gravity coefficients effect on the separation of the multi-phase melts and on the densification of the products are so obtained. Furthermore, the stress field simulation results show that the size and quality of compacts have remarkable effects on the stress field of ceramics. And the thermal stress decrease along with system temperature decrease.