Study On Fabrication And Properties Of YAG Ceramic Balls

Yttrium aluminum garnet (Y3Al5O12, YAG) is an important ceramic material with excellent chemical stability, high creep resistance and good mechanical properties, has potential as an advanced structural ceramics. It is also a promising solid-state laser material for its good optical performance. YAG ceramics are widely used in the fields of laser, electron, light-emitting materials and high temperature structural ceramics.In recently years, the YAG ceramic was as a laser host material in laser field. The general interest is to increase the transmittance of the ceramic and improve the efficiency of the laser output. The research focused on the preparation of YAG powders, the molding technology for large size and complex shape YAG ceramic, the sintering of ceramic. However, the research on YAG structural ceramics is few. In this thesis, the high purity and high wear resistance YAG ceramic balls were fabricated to reduce the introduction of impurities in the ball milling process to improve the cleanliness in the preparation of transparent YAG laser ceramics process. And the YAG structural ceramics were studied.The YAG ceramic green bodies were prepared by slip casting, and high purity Al2O3and Y2O3powders were used as raw materials. Through ball milling, the dispersed and homogeneous ceramic slurry was prepared via adjusting technological parameters of the Y2O3-Al2O3mixed slurry. According to rheological properties of the ceramic slurry to optimize the best parameters of YAG ceramic slurry process as follows:9.7in pH value,1.5wt%in dispersant (PAA-NH4),50wt%in solid loading, ball milling time for12h,1.5wt%in binder (PEG) content. After vacuum drying at60℃for24hours, the relative density of YAG green balls is up to50%, the roundness deviation is0.5346%, the particle distribute uniformly.YAG phase was synthesized by solid-state reaction method. Based on X-ray diffraction (XRD) analysis shows that:the YAG phase began to form when heats at1200℃, there was large number of YAG phase in the sample after calcined at1400℃for2hours, the phase composition is pure YAG phase after calcined at1500℃for2hours.The YAG ceramic balls were sintered by liquid phase sintering method, SiCO2powder added as sintering agent. The ceramic density testing and SEM analysis shows that the reasonable amount SiO2is0.8wt%, the optimum sintering process is pre-heating at1400℃for2hours, after cooling and then sintering at1650℃. Relative density of the YAG ceramic ball is98.83%, and the grain size is homogeneous, the grain boundaries are clean, and there is no pore in the grain and grain boundary when sintering at1650℃for8hours. YAG ceramic ball wear rate test and mechanical properties show that the crushing strength is2.395kN, the Vickers hardness is1910.60HV when sintering at1650℃for4hours. The mechanical properties of YAG ceramic are well, wear resistance of ceramic balls is the best when sintering at1650℃for6hours, the wearable modulus is5.68ppm/h.