Zgalat-Lozynskyy Ostap, Ragulya Andrey
Frantsevich Institute for Problems of Materials Science, 3, Krzhizhanovsky str., 03680, Kiev, Ukraine.
Nanoscale Res Lett. 2016 Dec;11(1):99. doi: 10.1186/s11671-016-1316-x. Epub 2016 Feb 24.
Microwave sintering (MWS) of commercially available 15-nm-size nanocrystalline TiN powder was studied. Densification kinetics and grain growth mechanisms of nano-TiN were evaluated using non-isothermal heating up to 1500 °C with variable heating rates. A true nanocrystalline ceramic with ~80-nm-size grains and 94.5 % theoretical density was obtained via MWS consolidation at 1400 °C. At higher temperatures, however, an uncontrolled grain growth and a formation of bimodal microstructure were noticed. A temperature dependence of grain growth suggested grain boundary sliding as a primary mechanism of densification below 1100-1200 °C. An activation energy of nano-TiN densification under MWS varied from 26 ± 3 kJ/mol at the initial stage of sintering (900-1200 °C) to 162 ± 22 kJ/mol at higher temperatures. In addition, a relationship coupling microstructural characteristics (grain size, grain boundary) with mechanical properties of titanium nitride ceramics obtained via both microwave and pressureless sintering techniques was discussed.
对市售15纳米尺寸的纳米晶TiN粉末进行了微波烧结（MWS）研究。通过在高达1500°C的非等温加热条件下以可变加热速率进行加热，评估了纳米TiN的致密化动力学和晶粒生长机制。通过在1400°C下进行MWS固结，获得了具有约80纳米尺寸晶粒和94.5%理论密度的真正纳米晶陶瓷。然而，在更高温度下，观察到晶粒生长不受控制且形成了双峰微观结构。晶粒生长的温度依赖性表明，在1100 - 1200°C以下，晶界滑动是致密化的主要机制。在MWS条件下，纳米TiN致密化的活化能在烧结初期（900 - 1200°C）为26±3 kJ/mol，在较高温度下为162±22 kJ/mol。此外，还讨论了通过微波烧结和无压烧结技术获得的氮化钛陶瓷的微观结构特征（晶粒尺寸、晶界）与力学性能之间的关系。
