Download PDFOpen PDF in browserHigh Strengthening and Toughing of DLC Coating via Pretreated Stainless Steel Dies by Massive Nitrogen Supersaturation8 pages•Published: August 6, 2026AbstractA duplex method has been invented and utilized as a protective coating of dies and tools to promote the wear toughness of main coating layer by inorganic buffer layer between the substrate and coating 1). DLC coating with a silicon buffer was widely used as a typical duplex coating system 2). However, the interfacial strength between the DLC coating and the buffered substrate often became insufficient to prevent the DLC-coated and buffered dies from wears in severe manufacturing conditions. A new interfacial material system design was needed to promote the interfacial strength and to significantly prolong the die and tool lives. A massive nitrogen supersaturation (MNS) was first invented to significantly harden the thick surface layer without the thermal distortion and without nitride precipitates 3). This MNSed surface layer had high nitrogen solute contents, nano-structure and high hardness. This was used as a new duplex method to improve the interfacial strength of DLC coating system 4-5).In the present paper, AISI420 stainless steel die was first plasma nitrided to have MNSed surface layer. After forming the silicon-buffer onto this pretreated surface, DLC film was coated to build up the coating system. The indentation and scratch tests were employed to evaluate the toughness and robustness of coating system with and without the MNS pretreatment. The onset of cracking and failure was significantly retarded by this pretreatment. Microstructure analysis with XPS demonstrated that interfacial bonding state among carbon in DLC, silicon in buffer and nitrogen in MNSed layer should be responsible for strengthening and toughing of DLC coating system to prolong the die life. Keyphrases: dlc coating, massive nitrogen supersaturated aisi420 dies strengthening, toughing, wear toughness In: Numpon Mahayotsanun (editor). Proceedings of The 11th International Conference on Tribology in Manufacturing Processes & Advanced Surface Engineering, vol 4, pages 9-16.
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