纳米Ti-Si-N薄膜的高温热稳定性

Thermal stability of nano-structure Ti-Si-N coatings at elevated temperature

用直流等离子体增强化学气相沉积(PCVD)方法在不锈钢基体上制备了Ti-Si-N硬质纳米复合薄膜,研究了Si含量对薄膜硬度的影响及高温退火对薄膜晶粒尺寸及其硬度的影响.结果表明:薄膜的硬度随着Si含量的增加有先增大后减小的趋势,最大硬度可达70 GPa以上.薄膜表现出了较高的热稳定性能,对于晶粒尺寸在4 nm以下的薄膜,Ti-Si-N薄膜的纳米结构和硬度可以维持在1000℃以上.沉积态薄膜的品粒尺寸是影响薄膜再结晶温度的主要因素.薄膜的高热稳定性是由于沉积过程中发生的自发调幅分解形成了纳米复合结构,偏析使得纳米晶晶界具有强的热力学稳定性.

The super-hard nanocomposite films of Ti-Si-N were prepared by direct current plasma enhanced chemical vapor deposition (PCVD) on stainless steel substrate. Dependence of Si content and annealing at elevated temperatures on the microstructure and hardness of Ti-Si-N coatings were investigated. The results showed that plastic hardness increased with the increase of the Si content and then decreased in these films. The maximum value hardness of exceeding 70 GPa can be achieved. Furthermore, the films show a superiority thermal stability. To as-received coatings of 4 nm crystallite size, the microhardness and crystallite size remain stable even at 1000°C. it was found that recrystallization temperature mainly depends on crystallite size of as-received films. The possible origin of high thermal stability of superhard nanocomposite was discussed. The results are explained by spinodal decomposition that occurs during deposition.