Reactions occurring in post heat-treated αβ sialons: On the thermal stability of α-sialon
Reactions occurring in post heat-treated αβ sialons: On the thermal stability of α-sialon
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热处理后的 αβ 赛隆中发生的反应：关于 α-赛隆的热稳定性
DOI：
10.1016/0955-2219(95)00213-8
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发表时间：
1996
影响因子：
5.7
通讯作者：
M. Nygren
中科院分区：
文献类型：
--
作者：
Zhijian Shen;T. Ekström;M. Nygren
向总体α-赛隆组合物R0.4Si10.2Al1.8O0.6N15.4（其中R=Nd、Sm、Dy和Yb）的粉末混合物中添加额外量的粉末混合物（20%），其Si:Al:R和O:N原子比分别为2:1:1和3:1。通过在 1750 °C 下无压烧结，由这些粉末制备了一系列含有约 20-30 vol% 玻璃相的富含 α 的混合 α/β-sialon 陶瓷。随后将所制备的样品加热至1750℃，然后淬火至室温或1150℃、1300℃和1450℃（冷却速率超过400℃/min），并在这些温度下退火不同时间。淬火至室温的样品显示，α-赛隆与β-赛隆在1750℃下共存并形成液相。最低温度下的后热处理涉及玻璃相的失透，并产生主要为稀土氮氧化物的混合物，如 U 相 R3Si3Al3O12N2、硅灰石 RSiO2N 或 B 相 Dy2SiAlO5N。 1450 °C 的后热处理引起 Nd 和 Sm 系统中残余液体和 α 相之间的反应，并在所有系统中产生富氧和富氮相的混合物。因此，黄长石相 R2Si3−xAlxO3+xN4−x 是由除 Yb 之外的所有稀土元素形成的，从而产生 Yb4Si2O7N2。 Nd-和Sm-系统中的富氧相是铝酸盐RAlO3，而在Dy-和Yb-系统中形成石榴石相R3Al5O12。淬火至 1300 °C 的样品也获得了类似的结果。这些发现表明α-赛隆的稳定性与所使用的烧结助剂的类型有关。根据退火实验中获得的结果，讨论了在所制备的样品中发现的相组合。
To a powder mixture of an overall α-sialon composition R0.4Si10.2Al1.8O0.6N15.4, with R = Nd, Sm, Dy and Yb, were added extra amounts of powder mixtures, (20%), having Si:Al:R and O:N atomic ratios of 2:1:1 and 3:1, respectively. Series of α-rich mixed α/β-sialon ceramics containing about 20–30 vol% glassy phase were prepared from these powders by pressureless sintering at 1750 °C. The as-prepared samples were subsequently heated at 1750 °C and then quenched to room temperature or to 1150, 1300 and 1450 °C (with a cooling rate exceeding 400 °/min), and were annealed at these temperatures for various times. The samples quenched to room temperature revealed that α-sialon coexists with β-sialon and a liquid phase at 1750 °C. The post heat-treatment at the lowest temperature involved a devitrification of the glassy phase and resulted in mixtures of mainly rare earth oxynitrides like the U-phase R3Si3Al3O12N2, wollastonite RSiO2N or the B-phase Dy2SiAlO5N. Post heat-treatment at 1450 °C induced a reaction between residual liquid and α-phase in the Nd- and Sm-systems and yielded a mixture of an oxygen- and a nitrogen-rich phase in all systems. Thus the melilite phase, R2Si3−xAlxO3+xN4−x, is formed with all rare earth elements except Yb, which yields Yb4Si2O7N2. The oxygen-rich phase in the Nd- and Sm-systems was the aluminate RAlO3, while in the Dy- and Yb-systems the garnet phase, R3Al5O12, was formed. Similar results were obtained with samples quenched to 1300 °C. These findings suggest that the stability of α-sialon is related to the type of sintering aid used. The phase assemblage found in the as-prepared samples is discussed in view of the findings obtained in the annealing experiments.
影响因子：
3.7
作者：
Whissell PD;Tohyama S;Martin LJ
通讯作者：
Martin LJ