Migration of Grain Boundary Phases for High Performance Ceramics.

AIN陶瓷含有5和10 wt%的Y_2O_O在N_2中稀释了1h的1800^0 C，在N_2中被淘汰了1h，在1900^0 C在N_2中被淘汰并减少了碳气体大气层。谷物边界相位，只包含Y_4Al_2O_9和Y_2O_3，减少了延迟时间。Y_4Al_2O_9将其分解为Y_2O_3和Al_2O_3，将其迁移到连接体的表面，并将其嵌入到表面上形成YN和AIN的表面层。热压AIN体没有添加剂和连接的AIN体，装有10wt%Y_2O_3在N_2中使用碳容器的1900^0 C加入和退火。“谷物边界阶段的初始迁移从交叉到热挤压的身体是由其集中梯度造成的。”颗粒边界相位与氧化物在热压体内反应，在热压体内反应氧化物的沉积中结果，两个液体相位在3 pbo、Fe_2O_3和WO_3反应中形成690^0和860^0 C，是PbFe_<2/3> W_<1/3>0_3 （指定PFW）的起始材料。high-temperature liquid phase has been demonstrated to form at 860^0 C on hating and to solidify at 840^0 C on cooling in PFW。在25^0 C/h之后缓慢冷却的速率下，通过接口、平板颗粒、设计的G相位，找到了形成一个薄表面层的规格。G帕赫对表面退化的量，加上冷却率的增加。这些结果表明，PFW的微观结构在高温液体相位上受到极大影响;另外，缓慢冷却的治疗似乎是一种直接有效的方法，可以将残留液体相位从PFW中去除。

The AIN ceramics containing 5 and 10 wt% Y_2O_O were densified at 1800^0C for 1h in N_2, and annealed at 1900^0C in N_2 and reducing carbon gas atmospheres. The grain boundary phases, containing both Y_4Al_2O_9 and Y_2O_3 only, decreased with increasing annealing time. Y_4Al_2O_9 decomposed into Y_2O_3 and Al_2O_3, which migrated towards the surface of the sintered body, and were nitrided on the surface to form a surface layer of YN and AIN. Hot-pressed AIN body without additive and sintered AIN body containing 10 wt% Y_2O_3 were joined and annealed at 1900^0C in N_2 using a carbon container. The initial migration of grain boundary phases from sintered to the hotーpressed body was caused by their concentration gradient. The grain boundary phases reacted with oxygen in the hotーpressed body, resulting in the depletion of oxygen in the hotーpressed body.Two liquid phases were formed around 690^0 and 860^0C by reaction of 3pbo, Fe_2O_3 and WO_3, which were starting materials of PbFe_<2/3>W_<1/3>0_3 (designate PFW). The high-temperature liquid phase has been demonstrated to form at 860^0C on hating and to solidify at 840^0C on cooling in PFW. Through slow cooling at the rate of 25^0C/h after sintering, platelike grains, designate G phase, are found to form a thin surface layer of specimens. The amount of G pahse on the surface decreases with the increase of cooling rate. These results reveal that the microstructure of PFW is greatly affected by the highーtemperature liquid phase ; additionally, the slow cooling treatment seems to be a direct and effective method for removing the residual liquid phase from PFW.