Nucleation control for hot-working of silicon oxynitride based ceramics
Nucleation control for hot-working of silicon oxynitride based ceramics
复制标题
氮氧化硅基陶瓷热加工成核控制
DOI：
10.1557/jmr.1999.0025
复制
发表时间：
1999
影响因子：
2.7
通讯作者：
S. Hampshire
中科院分区：
文献类型：
--
作者：
M. Ohashi;Y. Iida;S. Hampshire
试图开发一种在高温下可塑性变形、在高应变率下具有低流动应力且无应变硬化的工程陶瓷。通过在1500℃下无压烧结Si3N4+SiO_2混合粉末，添加MgAl_2O_4，利用Si2N_2O反应烧结过程中产生的瞬变液体进行净成形，得到致密的陶瓷预制件。陶瓷(6Φ×6 mm柱)在15 0 0°C的高应变率(10−2−10−3：S−1)下的压缩试验中没有出现裂纹和空洞，但在低应变率下长时间没有达到这一目标，这是因为在试验过程中长出了细长的Si2N2O颗粒。采用氟化钾(KF)作为掺杂剂，抑制Si2N2O在烧结和热加工过程中的形核。KF掺杂的预制体即使在长时间的实验中也能成功地塑性变形。
An attempt was made to develop an engineering ceramic plastically deformable at high temperatures with low flow stress at high strain rates, and without strain hardening. Dense ceramic preforms were fabricated by pressureless sintering Si_3N_4 + SiO_2 mixed powders with an addition of MgAl_2O_4 at 1500 °C. A transient liquid, which occurs during the reaction sintering of Si_2N_2O, was utilized for subsequent net-shape forming. The ceramic (6Φ × 6 mm column) was deformed without any cracks and cavities in compression tests at high strain rates (10^−2−10^−3:s^−1) at 1500 °C, but this was not achieved in a test at lower strain rates for a long time, because of the growth of elongated Si_2N_2O grains during the test. Potassium fluoride (KF) was used as a dopant for retardation of nucleation of Si_2N_2O during sintering and hot-working. The KF-doped preforms were successfully plastically deformed even in the test for a long time.