Nano silicon top-layer for composite-induced multiphasic enhancement of thermal stability of hardness of diamond-like carbon nanofilm at 900 °C

► The DLC film is crucial for protective coating in several mechanical applications. ► The element-doped DLC films exhibits poor thermal stability as up to 600 °C. ► Adding Si top-layer on DLC can enhance the stability of hardness up to 900 °C. ► It is due to the ambient isolation and formation of new phase, nanostructured SiC. ► This is a practical method for extending DLC high-temperature application.