β-Sialon-Nd-黄长石固溶体材料的生成和氧化行为

Formation and Oxidation Behavior of β-Sialon-Melilite Solid Solution Ceramics

研究了在β10－Sialon（Si5．23Al0.77O0．77N7，23）中加入7．26Wt％Nd-黄长石固溶体（Nd2Si2AlO4N3）组份的反应过程和致密化行为．烧结过程中，稀土元素先进入α－Sialon；随温度的升高，稀土元素存在于晶界玻璃相中，并在退火过程中以黄长石相析出．对热压及经退火处理的样品，研究了其在1000～1400℃的氧化行为．1000℃氧化时，作为晶界相的黄长石固溶体并不会导致样品开裂．但在更高温度氧化时，氧化后的表面存在择优取向的A－Nd2Si2O7晶粒，且由于Nd离子的表面偏析使表面氧化层软化而形成气泡．

The formation behavior of the composition of β10-Sialon(Si5.23Al0.77O0.77N7.2 3)plus 7.26wt%Nd-meilite sclid solution (Nd2Si2AIO4N,3) prepared by pressureless sintering was studied. Nd ionsin the composition enter α- sialon at low temperature, dissolve in the liquid phase of the materialwith temperature increasing. Melilite solid solution can be formed as a grain boundary phaseof the ceramics by heat-teatment at 1550℃ for 24h. The oxidation behavior of the hot-pressedand post-sintered samples was also investigated in the range of 1000-1400℃. The melilite solidsolution doesn't canes severe cracking of the material in oxidation at 1000℃. At high temperature,the oxidized surface of the sample contains preferentially oriented A--Nd2Si2O7 grains and bubbles,which are formed because of the decrease of the silicate viscosity, incurred by the accumulation ofNd ions to the surface.