权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Migration of Grain Boundary Phases for High Performance Ceramics.

高性能陶瓷的晶界相迁移。

基本信息

批准号：
01470069
负责人：
MIZUTANI Nobuyasu
金额：
$ 2.56万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01470069/
关键词：
Migration of grain boundary phase Aluminum nitride Lead complexーperovskite Relaxor ferroelectrics High thermal conductivity Liquid phase sintering Densification Heat treatment of reducimg atmosphere 鉛ペロブスカイト粒界粒界相移動

项目摘要

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.

将含有5 wt% Y_2O_O和10 wt% Y_2O_O的AIN陶瓷在1800℃的氮气中致密化1h，并在1900℃的氮气和还原碳气体气氛中退火。同时含有Y_4Al_2O_9和Y_2O_3的晶界相随着退火时间的延长而减少。Y_4Al_2O_9分解为Y_2O_3和Al_2O_3，向烧结体表面迁移，并在表面进行氮化，形成一层YN和AIN表面层。将未添加添加剂的热压AIN体与含有10 wt% Y_2O_3的烧结AIN体相结合，用碳容器在氮气中进行1900^0C的退火。晶界相从烧结体向热压体的初始迁移是由它们的浓度梯度引起的。晶界相与热压体中的氧发生反应，导致热压体中的氧耗竭。3pbo、Fe_2O_3和WO_3在690°c和860°c左右反应形成两个液相，分别作为PbFe_<2/3>W_<1/3>0_3（简称PFW）的起始原料。高温液相在加热时达到860°c，在PFW冷却时达到840°c凝固。烧结后以25℃/h慢速冷却，试样表面形成片状晶粒，为G相。随着冷却速率的增加，表面G - pahse的含量逐渐减少。结果表明：高温液相对PFW的微观结构影响较大；此外，缓慢冷却处理似乎是去除PFW中残余液相的直接有效方法。