Hering Benjamin, Wolfrum Anne-Kathrin, Gestrich Tim, Herrmann Mathias
Institute for Materials Science, Dresden University of Technology, 01062 Dresden, Germany.
Fraunhofer IKTS, Fraunhofer Institute for Ceramic Technologies and Systems, 01277 Dresden, Germany.
Materials (Basel). 2021 Mar 27;14(7):1642. doi: 10.3390/ma14071642.
Wear-resistant, super hard ceramic composites based on cubic boron nitride (cBN) are of great interest to industry. However, cBN is metastable under sintering conditions at normal pressure and converts into the soft hexagonal BN (hBN). Therefore, efforts are being made to avoid this process. Besides short sintering times, the use of coated cBN-particles is a way to minimize this process. Therefore, the thermal stability of TiN coated cBN powders in high purity argon and nitrogen atmospheres up to temperatures of 1600 °C was investigated by thermogravimetry, X-ray phase analysis, scanning electron microscopy and Raman spectroscopy. The TiN coating was prepared by the atomic layer deposition (ALD)-method. The investigations showed that the TiN layer reacts in Ar at T ≥ 1200 °C with the cBN and forms a porous TiB layer. No reaction takes place in nitrogen up to temperatures of 1600 °C. Nevertheless, the 20 and 50 nm thin coatings also undergo a recrystallization process during heat treatment up to temperatures of 1600 °C.
基于立方氮化硼（cBN）的耐磨超硬陶瓷复合材料受到工业界的广泛关注。然而，cBN在常压烧结条件下是亚稳态的，会转变为软质的六方氮化硼（hBN）。因此，人们正在努力避免这一过程。除了缩短烧结时间外，使用包覆cBN颗粒也是尽量减少这一过程的一种方法。因此，通过热重分析、X射线相分析、扫描电子显微镜和拉曼光谱研究了TiN包覆的cBN粉末在高达1600℃的高纯氩气和氮气气氛中的热稳定性。TiN涂层采用原子层沉积（ALD）法制备。研究表明，TiN层在T≥1200℃的氩气中与cBN反应，形成多孔的TiB层。在高达1600℃的温度下，在氮气中不发生反应。然而，20纳米和50纳米厚的涂层在高达1600℃的热处理过程中也会经历再结晶过程。
